SPP 2014 -Frequency Load Shedding (UFLS) Study 2014 ufls study final...spinning reserve is not adequate, Under-Frequency Load Shedding (UFLS) relays are used for initiating automatic

Prepared by

Powertech Labs Inc. (PLI)

For

Southwest Power Pool (SPP)

December 10, 2014

Prepared by: Saeed Arabi, Ph.D.

Principal Engineer, Power System Studies

Phone: (604) 590-7459

Email: [email protected]

Reviewed by: Zhihong Feng, Ph.D.

Manager, Power System Studies

Phone: (604) 590-7477

Email: [email protected]

Final Report

SPP 2014

Under-Frequency Load Shedding (UFLS)

Study

Powertech Report No: PL-00482-03

mailto:[email protected]

mailto:[email protected]

SPP 2014 UFLS Study

This document contains proprietary information and shall not be disclosed to any third party without the prior written permission of Powertech, SPP, or any SPP member.

ii

Acknowledgements

Powertech study team would like to thank Mr. Harvey Scribner of SPP for his assistance and

coordination during the course of this study.

The following Powertech personnel participated in this study:

Dr. Saeed Arabi

Dr. Zhihong Feng

Dr. Akshaya Moharana

Dr. Xianrong Wang

SPP 2014 UFLS Study


iii

Executive Summary

SPP Under-Frequency Load Shedding (UFLS) program was assessed for two islanding

situations; Southwest Power Pool (SPP) with Associated Electric Cooperative, Inc. (AECI) and

SPP with AECI and Western Area Power Administration (WAPA). The WAPA system inclusion

contains UFLS information for Basin Electric Power Cooperative (Basin), Western Area Power

Administration, Upper Great Plains (WAPA), Heartland Consumers Power District (HCPD),

Missouri River Energy Services (MRES), and Northwestern Public Service (NWE). The second

island (i.e., SPP+AECI+WAPA) also contains Corn Belt Power Cooperative (CBPC). The

islands were formed by tripping relevant ties, as well as disconnection of generating units to

create 25% load-generation imbalance as required by NERC PRC-006-1 Standard. The study

assumed that the entities not in SPP Plan followed their plan setting.

SPP provided detailed UFLS relay information in spreadsheet format, which was reviewed and

translated to appropriate models by Powertech Labs Inc. (PLI). Generator under-frequency and

over-frequency relays information were also translated to suitable models. PLI used an in-house

DSAToolsTM

software package for simulations.

Time-domain dynamic simulations verified the frequency criteria of the NERC Standard were

met in both islands. With respect to the under-frequency situation, the voltage magnitude

behaviors in these islands were also reasonable. The total load shedding was near 22%, while the

total available load for shedding was close to 30%. It may then be concluded that the current

UFLS program is adequate to meet the frequency criteria. Note that in both islands simulated in

this study, three generator under-frequency relays operated as well, which tripped around 400

MW of generation.

In both islands, Volts/Hertz was calculated for all individual generating units greater than 20

MVA or units at a generating facility greater than 75 MVA, as well as their transformer high-

side buses. The analysis was performed using bus voltage and frequency results of the 100-

second long dynamic simulations. The results were checked against both short-term and long-

term NERC Standard criteria. Only five minor long-term violations were observed, which were

considered to be within the simulation tolerances.

SPP 2014 UFLS Study


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Table of Contents

Executive Summary ....................................................................................................................... iii

1. Introduction ......................................................................................................................... 1-1

1.1 Background ................................................................................................................ 1-1 1.2 Objectives .................................................................................................................. 1-1

2. Scope and Study Approach ................................................................................................. 2-1 2.1 UFLS Program Requirements .................................................................................... 2-1 2.2 Volts per Hertz Evaluation......................................................................................... 2-1

2.3 Simulation Tools ........................................................................................................ 2-2

3. Data and Model Assembly .................................................................................................. 3-1 3.1 Power Flow and Dynamic Models ............................................................................. 3-1

3.2 Load Models .............................................................................................................. 3-2 3.3 UFLS Relay Models .................................................................................................. 3-3 3.4 SVC and STATCOM Models .................................................................................... 3-4

4. Islands and Scenarios .......................................................................................................... 4-1 4.1 Definition of Studied Islands ..................................................................................... 4-1 4.2 Definition of Imbalance ............................................................................................. 4-2

4.3 Historical Events ........................................................................................................ 4-2 4.3.1 June 25, 1998 Event in MAPP ................................................................................... 4-2

4.3.2 September 18, 2007 Event in MAPP ......................................................................... 4-3 4.3.3 June 17, 2008 Event in SPS ....................................................................................... 4-3

5. Island of SPP+AECI ............................................................................................................ 5-1

5.1 Scenario Descriptions ................................................................................................ 5-1

5.2 Frequency Simulation Results ................................................................................... 5-7 5.3 Sensitivity of an Entity with Peak Load under 75 MW ........................................... 5-11 5.4 Volts per Hertz Assessment ..................................................................................... 5-11

6. Island of SPP+AECI+WAPA .............................................................................................. 6-1 6.1 Scenario Descriptions ................................................................................................ 6-1

6.2 Frequency Simulation Results ................................................................................. 6-13 6.3 Effect of the Under-Voltage Issue ........................................................................... 6-14 6.4 Sensitivity of an Entity with Peak Load under 75 MW ........................................... 6-18 6.5 Volts per Hertz Assessment ..................................................................................... 6-19

7. Conclusions ......................................................................................................................... 7-1

8. Appendix A – Delivered Supporting Files .......................................................................... 8-1

SPP 2014 UFLS Study


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List of Tables

Table 3-1: Number of In-service Elements in Simulation Cases. ................................................ 3-1 Table 3-2: Areas Involved in the Two Islands. ............................................................................ 3-1 Table 3-3: Power Flow Summary of the Areas Involved in the Two Islands.............................. 3-2

Table 3-4: List of Loads with Dynamic Components. ................................................................. 3-3 Table 3-5: Number of UFLS and Generator Trip Relays by Area. ............................................. 3-3 Table 3-6: Summary of UFLS and Generator Trip Relays. ......................................................... 3-4 Table 3-7: Available Loads for UFLS Relays. ............................................................................ 3-4 Table 3-8: SVC/STATCOM Models of the Two Islands. ........................................................... 3-4

Table 4-1: Definition of the Two Islands. .................................................................................... 4-1 Table 4-2: Summary of June 25, 1998 Islanding Event............................................................... 4-2 Table 4-3: Summary of September 18, 2007 Islanding Event. .................................................... 4-3

Table 4-4: Summary of June 17, 2008 Frequency Excursion. ..................................................... 4-4 Table 5-1: Branch Tripping for SPP+AECI Island. ..................................................................... 5-1 Table 5-2: Generator Tripping for SPP+AECI Island. ................................................................ 5-4 Table 5-3: Generators with Non-responding Governors for SPP+AECI Island. ......................... 5-7

Table 5-4: Summary of Shunts Switching in SPP+AECI Island. ................................................ 5-7 Table 5-5: SPP+AECI Island Summary. ..................................................................................... 5-8

Table 5-6: SPP+AECI Island Load Sheds by Area. .................................................................... 5-8 Table 5-7: Generators Tripped by Under-frequency Relays in SPP+AECI Island. .................... 5-9 Table 5-8: Frequency Summary of SPP+AECI Island. ............................................................... 5-9

Table 5-9: Disarmed Entity in SPP+AECI Island for Sensitivity Study. .................................. 5-11 Table 5-10: SPP+AECI Island Load Sheds by Area – Sensitivity. ........................................... 5-11

Table 5-11: SPP+AECI Island V/Hz Results. ........................................................................... 5-12

Table 6-1: Branch Tripping for SPP+AECI+WAPA Island. ....................................................... 6-1

Table 6-2: Generator Tripping for SPP+AECI+WAPA Island. .................................................. 6-7 Table 6-3: Generators with Non-responding Governors for SPP+AECI+WAPA Island. ......... 6-11 Table 6-4: Summary of Shunts Switching in SPP+AECI+WAPA Island. ................................ 6-12

Table 6-5: SPP+AECI+WAPA Island Summary. ..................................................................... 6-13 Table 6-6: SPP+AECI+WAPA Island Load Sheds by Area. .................................................... 6-13

Table 6-7: Generators Tripped by Under-frequency Relays in SPP+AECI+WAPA Island. .... 6-14 Table 6-8: Frequency Summary of SPP+AECI+WAPA Island. ............................................... 6-14 Table 6-9: SPP+AECI+WAPA Island Load Sheds by Area – 7 Fictitious Synchronous

Condensers Added in WAPA. ............................................................................................. 6-15 Table 6-10: Frequency Summary of SPP+AECI+WAPA Island – 7 Fictitious Synchronous

Condensers Added in WAPA. ............................................................................................. 6-15

Table 6-11: Disarmed Entity in SPP+AECI+WAPA Island for Sensitivity Study. .................. 6-18

Table 6-12: SPP+AECI+WAPA Island Load Sheds by Area – Sensitivity. ............................. 6-18 Table 6-13: SPP+AECI+WAPA Island V/Hz Results. ............................................................. 6-19 Table 7-1: Summary of UFLS Operations and Frequencies. ....................................................... 7-1

SPP 2014 UFLS Study


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List of Figures

Figure 2-1: UFLS Program Design Performance and Modeling Curves. .................................... 2-3 Figure 5-1: Bus Voltage Magnitudes of SPP+AECI Island....................................................... 5-10 Figure 5-2: Bus Frequencies of SPP+AECI Island. ................................................................... 5-10

Figure 6-1: Bus Voltage Magnitudes of SPP+AECI+WAPA Island – No Fictitious Synchronous

Condensers Added............................................................................................................... 6-16 Figure 6-2: Bus Frequencies of SPP+AECI+WAPA Island – No Fictitious Synchronous

Condensers Added............................................................................................................... 6-16 Figure 6-3: Bus Voltage Magnitudes of SPP+AECI+WAPA Island – 7 Fictitious Synchronous

Condensers Added in WAPA. ............................................................................................. 6-17 Figure 6-4: Bus Frequencies of SPP+AECI+WAPA Island – 7 Fictitious Synchronous

Condensers Added in WAPA. ............................................................................................. 6-17

SPP 2014 UFLS Study


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1. Introduction

1.1 Background

Power system steady-state operation requires a balance between generation and load. A sudden

loss of generation due to abnormal conditions such as tripping generating units due to a fault

disturbs this balance and the system frequency begins to deviate from nominal. System operation

at low frequency may damage generator turbines and, if not corrected, can lead to cascaded

tripping of additional generation thereby further aggravating the situation. To arrest frequency

decline, the governors of generators with spinning reserve will attempt to make-up for the lost

generation. If the frequency decline is too fast and the governors cannot react fast enough or

spinning reserve is not adequate, Under-Frequency Load Shedding (UFLS) relays are used for

initiating automatic load sheds.

The UFLS scheme must be properly designed to include the following three requirements:

Avoid insufficient load shedding which in turn may lead to system blackout;

Prevent excessive load shedding which may result in over-frequency or over-voltage

conditions or unnecessary loss of service continuity;

Provide sufficient load shedding to maintain the frequency in the acceptable range.

A coordinated automatic UFLS program is required to maintain power system security during

major system frequency declines, i.e., islanding situations. The North American Electric

Reliability Corporation (NERC) has provided Reliability Standards for ensuring the proper

implementation of UFLS programs, i.e., Standard PRC-006-1, which includes the detailed

requirements for a regional UFLS program.

As part of compliance with the NERC requirements for its UFLS program, Southwest Power

Pool (SPP), as Planning Coordinator, commissioned this study to be performed by Powertech

Labs Inc. (PLI).

1.2 Objectives

The objectives of this project are to carry out dynamic simulations assuming generation loss

within the regional and sub-regional islands identified by SPP. This method will help to confirm

that the SPP UFLS schemes within the islands are effective in maintaining system security

following the loss of generation. This project should therefore address the following objectives:

To review SPP’s existing under-frequency (load and generation) and Automatic Load

Restoration (ALR) relays, and construct their dynamic data to be used for the simulation

of UFLS assessment. The relay models will be defined for each system area specified by

SPP;

To conduct time-domain simulations on each islanded system identified by SPP to

SPP 2014 UFLS Study


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determine if the UFLS program is effective and in compliance with NERC/SPP

requirements;

To recommend modifications to the UFLS scheme if deemed necessary (e.g., different

load shedding stages including percentages and time delays, etc.);

To evaluate over-voltage conditions resulting from UFLS, particularly to check potential

operations of Volts per Hertz relays on generators and generator step-up transformers

against the PRC-006-1 requirements;

To provide documentation detailing the study finding and recommendations.

SPP 2014 UFLS Study


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2. Scope and Study Approach

The scope of this project includes a review of the existing SPP UFLS program and simulations to

verify its performance against NERC specific performance criteria. Modifications to the program

are to be recommended, if necessary.

The study will examine system performance by conducting dynamic simulations of UFLS

schemes subjected to 25% imbalance1 between load and generation, and will include two

islanding scenarios as follows:

1) SPP+AECI (Associated Electric Cooperative, Inc.);

2) SPP+AECI+WAPA (Western Area Power Administration).

To accomplish the objectives of this project, a comprehensive power system model, suitable for

time-domain simulations involving significant frequency excursions, will be developed for each

of the above two islands.

2.1 UFLS Program Requirements

The current UFLS program is generally required to fulfill NERC Standard PRC-006-1. As a

result, the assessment criteria for this study may be summarized as follows:

Frequency shall remain within the under-frequency and over-frequency range of the

curve in Attachment 1 of PRC-006-1, which is recaptured below in Figure 2-1, either for

60 seconds or until a steady-state condition between 59.3 Hz and 60.7 Hz is reached (R3

requirements related to 3.1 and 3.2 of the standard);

Volts per Hertz (V/Hz) shall not exceed 1.18 per unit (pu) for longer than two seconds

cumulatively per simulated event, and shall not exceed 1.10 pu for longer than 45

seconds cumulatively per simulated event at each generator bus and generator step-up

(GSU) transformer high-tension bus associated with individual generating units greater

than 20 MVA (gross nameplate rating) directly connected to the Bulk Electric System

(BES), generating plants/facilities greater than 75 MVA (gross aggregate nameplate

rating) directly connected to the BES, or facilities consisting of one or more units

connected to the BES at a common bus with total generation above 75 MVA gross

nameplate rating (R3 requirements related to 3.3 of the standard).

2.2 Volts per Hertz Evaluation

The actual magnitude of flux in a generator stator or transformer core is difficult to measure. It

1 For intermediate imbalance levels, such as 13% and 22%, full dynamic simulations are not required but the

“equivalent inertia” method using spreadsheet calculations is recommended.

SPP 2014 UFLS Study


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can, however, be quantified in terms of V/Hz, since the operating magnetic flux in electric

machines is proportional to the ratio of the operating voltage to the electrical frequency.

Therefore, V/Hz provides a measure of generator stator and transformer core magnetic flux.

Excessive magnetic flux in generator or GSU transformer results in thermal damages to them,

which are typically cumulative. These damages include, but are not limited to, generator stator

and GSU transformer core damage, as well as degradation of insulation material. Excessive

magnetic flux may even cause unwanted operation of protection system.

As indicated above, there are two V/Hz ratio (pu/pu) criteria, namely, short-term and long-term.

The violations usually occur as the frequency recovers after considerable load shedding, which

may in turn cause significant increase in voltage magnitudes. Almost all generating units are

equipped with V/Hz limiters in their excitation systems.

Depending on their voltage control mechanisms, some shunt capacitor banks may switch out and

/or some reactors may switch in automatically in response to over-voltage conditions. Switchable

shunt timing is typically longer than that of the short-term V/Hz criteria (i.e., 2 seconds), but

shorter than that of the long-term criteria (i.e., 45 seconds). Within this time frame, some Under-

Load Tap-Changing (ULTC) transformer controls may also adjust their taps contributing to

lowering the voltages and thereby reducing long-term V/Hz violations. None of these are

normally modeled in time-domain simulations. Moreover, detailed data for such dynamic

modeling is not readily available.

It also should be pointed out that the simulations are usually designed to capture the worst-case

(or near worst-case) scenarios that may be much more severe than what may happen in reality,

i.e., eliminating (or greatly reducing) the time delays involved in various trips and outages that

eventually form the island with the lowest load-generation imbalance. Furthermore, the starting

point of the voltages and ULTC positions are important, which may affect both short-term and

long-term criteria violations. This study uses a peak system loading condition which may again

constitute a worst-case scenario in terms of over-voltages.

2.3 Simulation Tools

PLI uses in-house DSAToolsTM

software package for simulations (http://www.dsatools.com).

Specifically, the following two programs are used in this study:

Power-flow and Short-circuit Analysis Tool (PSAT)

Transient Security Assessment Tool (TSAT)

These programs automatically convert the power flow and most of the dynamic data from Power

System Simulator/Engineering (PSS/E) format. The non-convertible models are then set up using

http://www.dsatools.com/

SPP 2014 UFLS Study


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the User-Defined Modeling (UDM) capabilities of the programs provided that sufficient

information exists about the device in question. The non-convertible models that are considered

uncritical for the study are netted in the simulations.

Governor response is included for units with governor as modeled in the dynamic data. The list

of non-responding governors is later presented for each island.

Figure 2-1: UFLS Program Design Performance and Modeling Curves.

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3. Data and Model Assembly

3.1 Power Flow and Dynamic Models

SPP provided a power flow base case (2013MDWG_FINAL_14SUM_ds-RED) representing the

summer peak loading condition of year 2014, with the matching dynamic data file. Two reduced

power flow cases were then developed to represent the islands of this study. The case sizes are

summarized in Table 3-1, the areas that are involved in covering all islands are defined in Table

3-2, and the power flow summary of these areas is provided in Table 3-3.

The following were also applied to incorporate modeling requirements for this study:

Based on the provided list by SPP, governors on all non-responding generators were

nullified, as later listed for each island;

There was a total of 295 MW netted generation, which includes the non-convertible

models with no details available. Compared to the total generation in each island, this is

negligible and has no significant effect on the results.

Table 3-1: Number of In-service Elements in Simulation Cases.

Element Base Case SPP+AECI SPP+AECI+WAPA

AC Buses 27655 7660 8624

Generators 2427 542 619

Loads 16870 4584 5516

Fixed Shunts 88 7 14

Frozen Switched Shunts 448 276 289

Discrete Switched Shunts 2353 553 659

Continuous Switched Shunts 5 0 2

AC Lines 24804 6484 7273

Zero-impedance Lines (Z 0.0001) 460 69 70

Two-winding Transformers 5950 942 1147

Three-winding Transformers 1297 850 906

Two-terminal DC Links 11 0 4

Table 3-2: Areas Involved in the Two Islands.

Area No. Area ID Area Name

* 330 AECI Associated Electric Cooperative, Inc.

515 SWPA Southwestern Power Administration

520 AEPW American Electric Power

523 GRDA Grand River Dam Authority

524 OKGE Oklahoma Gas and Electric Company

525 WFEC Western Farmers Electric Cooperative

526 SPS Southwestern Public Service

527 OMPA Oklahoma Municipal Power Authority

531 MIDW Midwest Energy

534 SUNC Sunflower Electric Cooperative

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Area No. Area ID Area Name

536 WERE Westar

540 GMO KCP&L Greater Missouri Operations

541 KCPL Kansas City Power and Light Company

542 KACY Board of Public Utilities

544 EMDE Empire District Electric Company

545 INDN City of Independence

546 SPRM City Utilities of Springfield

640 NPPD Nebraska Public Power District

645 OPPD Omaha Public Power District

650 LES Lincoln Electric Services

* +652 WAPA Western Area Power Administration

* Non-SPP Areas. +

652 WAPA area contains UFLS information for Basin Electric Power Cooperative (Basin), Western Area Power

Administration, Upper Great Plains (WAPA), Heartland Consumers Power District (HCPD), Missouri River Energy

Services (MRES), and Northwestern Public Service (NWE). Corn Belt Power Cooperative (CBPC) is also included

in WAPA portion of the Island 2.

Table 3-3: Power Flow Summary of the Areas Involved in the Two Islands.

Area Generation Load* Bus Shunt Branch Shunt Charging Series Losses Export

No. ID MW MVAr MW MVAr MW MVAr MW MVAr MW MVAr MW MVAr MW MVAr

330 AECI 3414 721 4591 1107 0 -422 0 0 0 1183 133 1057 -1311 162

515 SWPA 2014 402 1012 258 0 -186 0 0 0 161 31 428 971 63

520 AEPW 10373 953 10442 1400 0 -1963 0 2 0 1594 242 3114 -311 -6

523 GRDA 1088 -28 1052 208 0 -92 0 0 0 174 21 350 16 -321

524 OKGE 7416 307 6603 1216 0 -1314 9 183 0 1940 154 1927 650 235

525 WFEC 1390 47 1480 359 0 -193 0 1 0 350 56 379 -146 -149

526 SPS 5873 698 6198 1644 0 -1370 7 613 0 1833 190 1731 -522 -86

527 OMPA 69 18 372 53 0 0 0 0 0 5 1 2 -304 -32

531 MIDW 161 -4 431 167 0 -72 0 194 0 306 9 50 -278 -37

534 SUNC 1129 74 1270 380 0 -246 0 0 0 443 33 310 -175 74

536 WERE 6198 601 6064 1509 0 -1334 11 52 0 1320 132 1837 -8 -142

540 GMO 1170 272 2025 494 0 -403 0 0 0 209 31 370 -886 19

541 KCPL 4349 1252 3648 579 0 -307 0 0 0 512 65 1111 636 382

542 KACY 573 73 554 127 0 0 0 -1 0 13 4 88 15 -129

544 EMDE 1024 122 1157 190 0 -231 0 0 0 106 33 253 -166 17

545 INDN 132 -22 311 95 0 -72 0 0 0 7 3 28 -182 -66

546 SPRM 767 233 773 201 0 -57 0 0 0 102 11 174 -17 18

640 NPPD 3284 313 3777 1117 0 -1293 0 301 0 1306 135 1348 -628 146

645 OPPD 3120 838 2849 768 0 -106 0 13 0 392 31 663 240 -108

650 LES 201 16 755 133 0 -162 0 0 0 87 9 153 -562 -21

652 WAPA 5155 587 3679 1108 1 -444 0 780 0 3141 186 2410 1288 -125

* Includes station service loads.

3.2 Load Models

SPP provided load models to be used for this study. The models are mostly static and consist of

various area-based constant power, constant current, and constant impedance components.

Furthermore, some loads are represented by bus-based complex load (CLODBL) model in the

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dynamic data file, as listed in Table 3-4 (all in the WAPA area). Note that no frequency-

dependent load model is applied; it represents worst-case condition as frequency-dependence

would provide some load relief at reduced frequencies.

Table 3-4: List of Loads with Dynamic Components.

Bus # Bus Name ID Area # Area ID Model Load MW Load MVAr

659215 AVSDGC49 13.8 * 652 WAPA CLODBL 28.9 9.024

659221 AVSDG109 13.8 * 652 WAPA CLODBL 28.9 9.024

3.3 UFLS Relay Models

SPP provided detailed UFLS relay information in spreadsheet format which was cleaned up after

several updates by responsible members. The final cleaned up files are provided to SPP as listed

in Appendix A. They are mostly bus-based and were translated to LDSHBL standard PSS/E

model. There are also a number of load shedding relays based on branch (feeder) tipping; they

were represented by User-Defined Models (UDMs) in TSAT, as no standard PSS/E model was

available for such shedding. Generator under-frequency and over-frequency protection relays

were modeled by FRQTPA standard PSS/E model.

Per area number of all relays is provided in Table 3-5, as well as a summary of the relay

characteristics in Table 3-6. The created data files are provided to SPP as supporting material

(see Appendix A). The UFLS models have one to three stages triggered at 59.3, 59.0, and 58.7

Hz, with various relay and breaker delays. The available load for shedding by these relays in

each island is listed in Table 3-7. Note that in this table the relays with long delays (such as those

corresponding to generator service loads) are not accounted for, as they would not operate in this

study. Furthermore, no Automatic Load Restoration (ALR) information was provided.

Table 3-5: Number of UFLS and Generator Trip Relays by Area.

Area Number of Relays

# ID LDSHBL UDM Load Shed FRQTPA

330 AECI 144 0 0

515 SWPA 6 0 4

520 AEPW 228 60 8

523 GRDA 26 8 0

524 OKGE 115 88 0

525 WFEC 157 0 15

526 SPS 129 78 96

527 OMPA 24 0 0

531 MIDW 6 0 0

534 SUNC 50 3 5

536 WERE 120 36 25

540 GMO 43 0 16

541 KCPL 52 0 5

542 KACY 17 0 6

544 EMDE 53 0 34

545 INDN 4 0 0

546 SPRM 15 0 0

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Area Number of Relays

# ID LDSHBL UDM Load Shed FRQTPA

640 NPPD 38 6 19

645 OPPD 27 0 62

650 LES 17 0 8

652 WAPA 248 0 0

Total 1519 279 303

Table 3-6: Summary of UFLS and Generator Trip Relays.

Model Location Shed Elements Number Frequency Range (Hz)

Maximum Minimum

LDSHBL

AECI Loads (Up to 3 Stages) 144 59.3 58.7

SPP Loads (Up to 3 Stages) 1127 59.3 58.7

WAPA Loads (Up to 3 Stages) 248 59.3 58.7

Total 1519 59.3 58.7

UDM

Load Shed

AECI Transmission Line 0 - -

SPP Transmission Line 279 59.3 58.3

WAPA Transmission Line 0 - -

Total 279 59.3 58.3

FRQTPA

AECI Generators (Under/Over Speed) 0 - -

SPP Generators (Under Speed)

Generators (Over Speed)

289

14

58.8

66.0

54.5

61.2

WAPA Generators (Under/Over Speed) 0 - -

Total 303 66.0 54.5

Table 3-7: Available Loads for UFLS Relays.

Island Name Total Island Load

(MW)

Available Load for UFLS

MW %

SPP+AECI 55309.87 16581.19 29.98

SPP+AECI+WAPA 58952.30 17406.71 29.53

3.4 SVC and STATCOM Models

Static VAr Compensators (SVCs) and Static Synchronous Compensators (STATCOMs) are fast

voltage controlling devices. In particular, their modeling is important regarding the control of

over-voltages that might occur as a result of severe load shedding. The related models of the

studied islands are listed in Table 3-8.

Table 3-8: SVC/STATCOM Models of the Two Islands.

Bus # Bus Name ID Area # Area ID Model Min MVAr Max MVAr

524485 CAPROCK_WND134.5 DA 526 SPS CSVGN1 -16 48.4

525820 TUCO_SVC 113.0 1 526 SPS CSVGN1 -50 150

527790 EDDY_SVC 18.50 1 526 SPS CSVGN1 -50 100

539633 MRWYG21 34.5 SV 534 SUNC CSTATT -4 4

539636 MRWYG11 34.5 SV 534 SUNC CSTATT -4 4

640419 ELKRDG.PLT D34.5 D 640 NPPD CSTATT -4 4

640423 CROFTN.PLT D34.5 D 640 NPPD CSTATT -4 4

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4. Islands and Scenarios

Two generation-deficiency islanding scenarios are analyzed in this study, representing SPP

Regional Islands. In a real power system, usually it takes some time (likely several minutes) for

an island to form and perhaps even longer time to reach the highest imbalance. However, the

worst-case scenario of tripping all elements at once is preferred for simulations (no fault

applied). This approach has been sufficient for both islands.

4.1 Definition of Studied Islands

The two islands are defined in Table 4-1 in terms of areas. The islands are comprised of SPP

transmission system and associated buses, as well as some non-SPP areas, i.e., 330 (AECI) and

652 (WAPA).

Table 4-1: Definition of the Two Islands.

SPP+AECI SPP+AECI+WAPA

Area No. Area ID Area No. Area ID

330 AECI 330 AECI

515 SWPA 515 SWPA

520 AEPW 520 AEPW

523 GRDA 523 GRDA

524 OKGE 524 OKGE

525 WFEC 525 WFEC

526 SPS 526 SPS

527 OMPA 527 OMPA

531 MIDW 531 MIDW

534 SUNC 534 SUNC

536 WERE 536 WERE

540 GMO 540 GMO

541 KCPL 541 KCPL

542 KACY 542 KACY

544 EMDE 544 EMDE

545 INDN 545 INDN

546 SPRM 546 SPRM

640 NPPD 640 NPPD

645 OPPD 645 OPPD

650 LES 650 LES

6522 WAPA

2 652 WAPA area contains UFLS information for Basin Electric Power Cooperative (Basin), Western Area Power

Administration, Upper Great Plains (WAPA), Heartland Consumers Power District (HCPD), Missouri River Energy

Services (MRES), and Northwestern Public Service (NWE). Corn Belt Power Cooperative (CBPC) is also included

in WAPA portion of the Island 2.

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4.2 Definition of Imbalance

For each of the two islanding situations a load-generation imbalance scenario of about 25% is

developed, as required in PRC-006-1 R3:

Imbalance = [(Load – Actual Generation Output) / (Load)], where,

Load = (PLOAD of All In-service Loads within the Island)

+ (Losses within the Island)

– (PLOAD for All Left In-Service Station Loads of Out-Of-Service Generators)

– (PLOAD for All Station Loads Tripped to Create the Imbalance),

Actual Generation Output = (PGEN for All In-Service Generators within the Island)

– (Generation Removed to Create the Imbalance).

Details of the tripped elements to create the islands and proper imbalances, along with the

simulation results of their analysis, are presented in the following two sections for each island

separately. Note that all simulations are performed for 100 seconds.

4.3 Historical Events

NERC Standard PRC-006-1 requires each Power Coordinator (PC) to develop and document

criteria including consideration of historical events (requirement R1). In this respect, three

historical events are described below.

The historical events noted below were reviewed for their impacts on the Eastern

Interconnection. It was determined the identified events had no negative impact on the choice of

the SPP PC UFLS islands selected for this evaluation.

4.3.1 June 25, 1998 Event in MAPP

An historical islanding event occurred on June 25, 1998, in MAPP (Mid-continent Area Power

Pool) overlapping area 652 (WAPA). The island formed by this cascading event is summarized

in Table 4-2.

Table 4-2: Summary of June 25, 1998 Islanding Event.

Date June 25, 1998

Initial Island Frequency 60.8 Hz

Island Geographic Description Portions of North Dakota, Minnesota, South Dakota, Montana, Wisconsin,

and portions of Canadian provinces of Manitoba and Saskatchewan

After 2 Minutes from Initial Event NW Ontario Hydro collapsed

After 4 Minutes from Initial Event

Remaining big island broke into two, i.e., North Dakota, eastern portion of

Montana, northern South Dakota, and western Minnesota systems

separating from the rest

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Date June 25, 1998

Generation Loss

Many generating units tripped in North Dakota island, where transient

frequency reached 62.2 Hz and stabilized around 61.3 Hz for about 30

minutes

Load Loss None (no under-frequency)

Involved Entity of Concern Western Area Power Administration (WAPA)

After 41 Minutes from Initial Event Operators reduced generation and pushed frequency down to 60 Hz, and

the island was reconnected to the Eastern Interconnection

4.3.2 September 18, 2007 Event in MAPP

An historical islanding event occurred on September 18, 2007, in MAPP (Mid-continent Area

Power Pool) overlapping area 652 (WAPA). The island formed by this event is summarized in

Table 4-3.

Table 4-3: Summary of September 18, 2007 Islanding Event.

Date September 18, 2007

Island Geographic Description North Dakota, part of Minnesota, Manitoba, part of South Dakota, and

Saskatchewan

Within a Few Seconds Saskatchewan separated from the initial island

Causes of Islanding

The two 345 kV lines that formed the Minnesota-Wisconsin Stability

Interface (MWSI) tripped (before construction of the Arrowhead – Stone

Lake 345 kV line); moreover, on the day of the event some tie lines were

out for maintenance, while others tripped during the islanding event

mostly by overload or out-of-step condition

Involved Entity of Concern Western Area Power Administration (WAPA)

Within 10 Minutes from Initial Event The island was reconnected to the Eastern Interconnection through

automatic reclosing

Within 1 hour from Initial Event Eastern Interconnection was restored to normal conditions and all loads

were restored

4.3.3 June 17, 2008 Event in SPS

An historical UFLS event occurred on June 17, 2008, in SPS Area. A summary of the event is

presented in Table 4-4, which points to the first stage of UFLS relays (i.e., @ 59.3 Hz) being

activated. Note that currently there are 207 UFLS relays in area 526 (SPS). SPS Balancing

Authority (SPS BA) covers 52,000 square miles from Southeastern New Mexico through the

Texas panhandle into Oklahoma, and a small area in Kansas. The SPS BA is located in a semi-

arid region comprised of plains cut by seasonal waterways. The area’s altitude of about 3000 feet

above sea level and low humidity causes daily temperature swings of about 30 degrees

Fahrenheit. The region is sparsely populated with scattered small towns. The two main

population centers are Lubbock with a population of 210,000 and Amarillo with a population of

190,000. Both centers are in Texas. The principal industries in the SPS BA are agriculture and

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oil and gas extraction and processing. There is some potash mining in southeast New Mexico.

Table 4-4: Summary of June 17, 2008 Frequency Excursion.

Date and Time June 17, 2008 at 20:35

Lowest Frequency 59.156 Hz

Generation Loss Over 760 MW

Load Loss Approximately 657 MW per SCADA Area Load Graph, and

Approximately 642 MW per Under-frequency Load Shedding

Transmission Involved Approximately 400 miles of transmission lines including some tie lines

Involved Entity of Concern Southwestern Public Service (SPS)

Root Causes and Major

Contributory Factors Tie line out for maintenance followed by the unexpected loss of generation.

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5. Island of SPP+AECI

5.1 Scenario Descriptions

The ties that are tripped to create this island and the generators that are disconnected to produce

the proper imbalance are listed in Table 5-1 and Table 5-2, respectively. SPP provided a list of

candidate generators for tripping ranked with priority 1 and priority 2; the units with priority 1

are those preferred to be shed first. The tripped units were all chosen from the first priority set,

except for four units in area 515 (SWPA), totaling to 383.3 MW, that were included due to their

instability (no unit in this area was designated by SPP).

Generators with non-responding governors, as provided by SPP, are also listed in Table 5-3.

Furthermore, some available switchable shunts were moved, as summarized in Table 5-4, to

prevent extreme low/high voltages observed at a few nearby generator buses. Note that such

switching would normally take place within the actual islanding process. The list is intentionally

kept to a minimum since it is not possible to predict exactly which shunts will move in practice.

Table 5-1: Branch Tripping for SPP+AECI Island.

1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

300030 8GPDELL 500. 338187 8DELL 500. Z1

300036 5MPLTAP 161. 344923 5LATHROP 161. 1

300038 7ESSEX 345. 344974 7LUTESVIL 345. 1

300041 7FRANKS 345. 344154 7BLAND 345. 1

300041 7FRANKS 345. 344327 7LOOSECRK 345. 1

300044 7MCCRED 345. 345088 7MCCREDIE 345. Z1

300053 5OLDMARS 161. 345024 4MARIES 138. 1

300057 5BARNET 161. 344026 5APCH TP 161. 1

300057 5BARNET 161. 344532 5ELDON 161. 1

300058 5SPALDNG 161. 344697 5HNBL 1 161. 1

300058 5SPALDNG 161. 345034 5MARN TAP 161. 1

300059 5BIG CK 161. 345542 5PT.PRAIR 161. 1

300059 5BIG CK 161. 345941 5WARENTN 161. 1

300061 5BOONE 161. 343014 5GRINDSTN 161. 1

300063 5CALIF 161. 344233 5CALIF UE 161. 1

300065 5CAMDTP 161. 344257 5CAMDEN UE 161. 1

300075 5ESSEX 161. 345790 5STODDARD 161. 1

300077 5FLETCH 161. 344179 5BR CREEK 161. 1

300077 5FLETCH 161. 344566 1FLETCHER 34.5 1

300077 5FLETCH 161. 345511 5PILTSS 161. 1

300077 5FLETCH 161. 345798 5SWEETWTR 161. 1

300079 5FREDTN 161. 344586 5FREDTOWN 161. 1

300079 5FREDTN 161. 345976 5WEDEKN T 161. 1

300083 5GIBSON 161. 338202 5JIMHL 161. 1

300097 5MARYVL 161. 652560 CRESTON5 161. 1

300098 5MOCITY 161. 344558 5EX SPRNG 161. 1

300103 5NEWMAD 161. 338201 5PRTGVL 161. 1

300103 5NEWMAD 161. 361261 5TIPTONVL TN161. 1

300106 5NOVELY 161. 344006 5ADAIR3 161. 1

300113 5SRIVER 161. 345437 5PALMYRA 161. 1

300115 5STFRAN 161. 338202 5JIMHL 161. 1

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1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

300120 5THMHIL 161. 344004 5ADAIR1 161. 1

300121 5MORLEY 161. 345375 5ORAN 161. 1

300121 5MORLEY 161. 345790 5STODDARD 161. 1

300126 5MOBTAP 161. 345221 5MOBERLY 161. 1

300179 2HAMBRG 69.0 635055 PERCIVL8 69.0 1

300426 2MILTNWY 69.0 630691 MILTON 8 69.0 1

300431 2BATAVI 69.0 630036 JEFF 8 69.0 1

300434 2PRMRST 69.0 630683 DONLSON8 69.0 1

300438 2HARSTP 69.0 630692 BONPRT18 69.0 1

300439 2HENRY 69.0 631106 HENRYCO5 161. 1

300439 2HENRY 69.0 631106 HENRYCO5 161. 2

300446 2PRIMRS 69.0 630690 HOUGHTN8 69.0 1

300448 2SAWYER 69.0 630013 VIELE 8 69.0 1

300448 2SAWYER 69.0 630659 IAAP TAP 69.0 1

300452 2WOOSTR 69.0 630036 JEFF 8 69.0 1

300453 2WPOINT 69.0 630684 WEST PT8 69.0 Z1

300465 2KEOSAQ 69.0 630691 MILTON 8 69.0 1

300465 2KEOSAQ 69.0 630692 BONPRT18 69.0 1

300466 2MARK 69.0 630033 APANOSE8 69.0 1

300467 2OTTUMW 69.0 630409 S OTTUM8 69.0 1

300480 5OFALLON 161. 345091 5MIDR 161. 1

300482 2MORAVA 69.0 630414 MORAVIT8 69.0 Z1

300487 2TRAIL 69.0 630387 ALBIA 8 69.0 1

300493 2BOONE 69.0 343006 2GRINDSTN 69.0 1

300496 2COLMBIA 69.0 343003 2PLANT 69.0 1

300499 5HINTON 161. 343001 5BOLSTAD 161. 1

300500 5HUNTSDL 161. 343004 5PERCHE 161. 1

300500 5HUNTSDL 161. 345409 5OVERTON 161. 1

300501 5MCBAIN 161. 345071 5MCBAIN T 161. 1

300504 2SHAW 69.0 343050 2BOLSTAD2 69.0 1

300506 2SWITZR 69.0 343050 2BOLSTAD2 69.0 1

300593 5COTLE1 161. 344773 5HWY N 161. 1

300593 5COTLE1 161. 345091 5MIDR 161. 1

300595 5CYRENE 161. 345498 5PIKE S 161. 1

300596 5DARDEN 161. 344773 5HWY N 161. 1

300597 5ENON 161. 344535 7ENON 345. 1

300597 5ENON 161. 344630 5GM 161. 1

300597 5ENON 161. 345542 5PT.PRAIR 161. 1

300599 4KISKER 138. 344880 4KISKER T 138. 1

300606 5TROY 161. 344449 5DARD12 161. 1

300606 5TROY 161. 344480 5TROYUE 161. 1

300718 5CLEVCOV 161. 338120 5LEAD HL 161. 1

300756 5STEELE 161. 338200 5HAYTI 161. 1

300756 5STEELE 161. 338804 5BLYN# 161. 1

300858 5SMRSVLEST 161. 345798 5SWEETWTR 161. 1

301101 2COUCH 69.0 338217 2THAY-N 69.0 1

301124 5COXCRK 161. 338215 5THAY-S 161. 1

301144 4PRIDGE 138. 344360 4CLARK O-R 138. 1

301263 2FLETCH 69.0 344566 1FLETCHER 34.5 1

301273 2PILOTK 69.0 345510 5PILTMA 161. 1

301406 8WNEWMADRID 500. 338187 8DELL 500. 1

503912 FULTON 3 115. 338875 3PATMOS# 115. 1

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1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

504080 GLENCOE 5 161. 338220 ASH FLT5 161. 1

505418 JONESBO5 161. 338170 5JONES 161. 1

505420 HERGETT5 161. 338170 5JONES 161. 1

505420 HERGETT5 161. 338707 5TRUM-W# 161. 1

505422 GREERSF5 161. 338758 5HEBR-N# 161. 1

505428 SIKESTN5 161. 345203 5MINER 161. 1

505442 WATER V5 161. 338220 ASH FLT5 161. 1

505442 WATER V5 161. 338223 5WATVAL* 161. 1

505448 NORFORK5 161. 338130 5CALCR 161. 1

505448 NORFORK5 161. 338814 5SOLAND# 161. 1

505460 BULL SH5 161. 338110 5HILLTOP 161. 1

505460 BULL SH5 161. 338120 5LEAD HL 161. 1

505460 BULL SH5 161. 338123 5BULLSH* 161. 1

505460 BULL SH5 161. 338813 5MIDWAY# 161. 1

505472 TABLE R5 161. 338099 5GDVIEW 161. 1

505508 DARDANE5 161. 337903 5DARDAN 161. 1

505508 DARDANE5 161. 337904 5RUSL-S 161. 1

505508 DARDANE5 161. 338110 5HILLTOP 161. 1

506932 EUREKA 5 161. 338099 5GDVIEW 161. 1

506932 EUREKA 5 161. 338682 5OSAGE # 161. 1

507195 MAGZREC5 161. 337902 5DANVI 161. 1

507434 SNASHVL4 138. 337672 4MURFRE 138. 1

507460 PRESCOT3 115. 337507 3PRESCT 115. Z1

507760 SW SHV 7 345. 500250 DOLHILL7 345. 1

507765 WALLAKE4 138. 500430 IPAPER 4 138. 1

507788 MINDEN-3 115. 337361 3MINDEN 115. 1

508359 WELSH 7 345. 599892 EASTDC 7 345. DC 15

508809 LONGWD 7 345. 337376 7SAREPT 345. 1

509241 CROCKET7 345. 334028 7GRIMES 345. 1

511456 O.K.U.-7 345. 599891 OKLAUN 7 345. DC 14

515305 FTSMITH8 500. 337909 8ANO 50 500. 1

523853 FINNEY 7345. 599950 LAMAR7 345. 1

524911 ROSEVELT_S 6230. 599955 PNM-DC6 230. Z1

527799 EDDY_NORTH 6230. 599960 EPTNP-D6 230. @1

541201 SIBLEY 7 345. 345408 7OVERTON 345. 1

541241 SEDEAST5 161. 345409 5OVERTON 161. 1

541251 MARYVLE5 161. 635034 CLRNDA 5 161. 1

543060 CAROLTN5 161. 344558 5EX SPRNG 161. 1

543062 SALSBRY5 161. 345221 5MOBERLY 161. 1

547474 OZD312 5 161. 338105 5OMAHA * 161. 1

640084 BLMFLD 7 115. 652511 GAVINS 7 115. 1

640133 COLMBUS4 230. 652509 FTRANDL4 230. 1

640139 COOPER 3 345. 635017 ATCHSNT3 345. 1

640192 GORDON 7 115. 659152 SHAN-SD7 115. 1

640212 HARTGTN7 115. 652511 GAVINS 7 115. 1

640226 HOSKINS3 345. 635200 RAUN 3 345. 1

640252 KEYSTON3 345. 659133 SIDNEY 3 345. 1

640349 SPENCER7 115. 652510 FTRANDL7 115. 1

640351 ST.FRANC 115. 652482 MISSION7 115. 1

640377 TEKAMAH5 161. 635201 RAUN 5 161. 1

640386 TWIN CH4 230. 652565 SIOUXCY4 230. 1

640396 VICTRYH4 230. 652573 STEGALL4 230. 1

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1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

640404 WAYSIDE4 230. 640405 WAYSIDE7 115. 1

Tertiary 640406 WAYSIDE9 13.8

645451 S3451 3 345. 635200 RAUN 3 345. 1

645456 S3456 3 345. 635000 CBLUFFS3 345. 1

646206 S1206 5 161. 635001 CBLUFFS5 161. 1

646211 S1211 5 161. 635003 SUB701 5 161. 1

652571 GR ISLD3 345. 652506 FTTHOMP3 345. 1

659134 SIDNEY 4 230. 652584 SIDNEYW4 230. DC 10

659134 SIDNEY 4 230. 659210 SIDXFMR4 230. 1

Total Tripped MW Import 2878.51

Table 5-2: Generator Tripping for SPP+AECI Island.

Bus # Bus Name ID MW Generation Comment

300001 1THLG1 20.0 1 150.00 Priority 1

300002 1THLG2 22.0 1 217.43 Priority 1

300010 1STFRG1 16.0 1 210.00 Priority 1

505432 SIKGEN 1 13.8 1 235.00 Tripped due to instability

505466 BSH3&4 1 13.8 4 45.70 Tripped due to instability



509394 FLINTCR1 22.0 1 514.00 Priority 1

509404 WELSH1-1 18.0 1 525.00 Priority 1

509405 WELSH2-1 18.0 1 525.00 Priority 1

509406 WELSH3-1 18.0 1 525.00 Priority 1

511840 NES3-1 22.0 1 400.00 Priority 1

511842 RSS1-1 24.0 1 350.00 Priority 1

512686 SALINA 5 161. 1 41.11 Priority 1

512686 SALINA 5 161. 2 41.11 Priority 1

512686 SALINA 5 161. 3 41.11 Priority 1

512689 GRDA15-1 22.8 1 435.00 Priority 1

512711 SALINA2 161. 4 36.00 Priority 1

512711 SALINA2 161. 5 36.00 Priority 1

512711 SALINA2 161. 6 36.00 Priority 1

514001 CRSRD-WTG1 0.69 1 21.00 Priority 1

514005 KEENAN-WTG1 0.69 1 7.00 Priority 1


514013 MINCO-WTG1 0.69 1 9.00 Priority 1

514084 OUSPRT-WTG1 0.69 1 9.00 Priority 1

514191 TALOGA-WG12 0.69 1 4.00 Priority 1



514805 SOONER1G 22.0 1 515.00 Priority 1

515040 SEMINL1G 20.9 1 349.65 Priority 1

515223 MUSKOG4G 18.0 1 504.00 Priority 1

515362 SLPBRAD-WTG10.69 1 11.00 Priority 1

515479 CHSHMVE1 34.5 1 11.50 Priority 1

515484 CHSHMVW1 34.5 1 18.00 Priority 1

515564 ORIGIN11 34.5 1 3.50 Priority 1

515565 ORIGIN21 34.5 1 3.50 Priority 1

515606 CANDN11 0.69 1 10.00 Priority 1

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515790 FPLMRLND-WG10.69 1 4.80 Priority 1

520947 HUGO1 23.4 1 440.00 Priority 1

522875 LP-BRANDON 269.0 1 20.00 Priority 1

523087 TC-TXCOUNTY134.5 1 0.73 Priority 1


523116 BUFF_DUNES1134.5 1 4.60 Priority 1


523165 SHERMAN 134.5 1 1.66 Priority 1


523183 SPEARMAN 134.5 1 0.62 Priority 1

523255 ETTER 134.5 1 0.98 Priority 1

523255 ETTER 134.5 2 1.36 Priority 1

523301 MOORE_E 113.2 1 1.23 Priority 1

523301 MOORE_E 113.2 3 1.17 Priority 1

523307 DUMAS WTG 0.69 1 4.28 Priority 1

523317 DUMAS_19ST 134.5 1 1.29 Priority 1


523354 HERRING 134.5 2 0.36 Priority 1

523815 LLANO_WND 3115. 1 6.77 Priority 1

523866 CHANNING 134.5 1 0.18 Priority 1

523923 CARSON_SUB 113.8 1 4.89 Priority 1

523941 MAJSTC-WTG110.69 1 3.50 Priority 1


523973 HARRNGTON3 124.0 1 339.00 Priority 1

524285 WILDORA_GEN10.69 1 30.07 Priority 1

524287 GS-PHWD_GEN10.69 1 2.00 Priority 1

524295 SPNSPUR_WND10.69 1 16.10 Priority 1

524485 CAPROCK_WND134.5 1 7.60 Priority 1

525841 ANTELOPE_A 113.8 A1 9.30 Priority 1





525942 HENDRICKS 122.9 1 0.82 Priority 1

526332 JONES_2 122.0 1 225.02 Priority 1

527163 MUSTANG_3 122.0 1 164.00 Priority 1

527881 CUNINGHAM1 113.8 1 31.00 Priority 1


528224 HOPI_SUB 112.5 1 7.00 Priority 1

528331 ASGI10-010 113.8 1 8.40 Priority 1

528331 ASGI10-010 113.8 2 8.40 Priority 1

528331 ASGI10-010 113.8 3 8.40 Priority 1

528332 WILDCAT_WND134.5 1 2.00 Priority 1

528490 MONUMENT 112.5 1 7.00 Priority 1

528504 LEA_ROAD 112.5 1 7.00 Priority 1

528546 S_JAL 112.5 1 7.00 Priority 1

528560 DOLLARHIDE 112.5 1 7.00 Priority 1

530555 COLBY 3 115. C3 0.22 Priority 1

530555 COLBY 3 115. C6 3.50 Priority 1

530555 COLBY 3 115. C7 3.60 Priority 1

530555 COLBY 3 115. C8 2.00 Priority 1

530575 N ELWD 2 69.0 E1 1.90 Priority 1

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530575 N ELWD 2 69.0 E2 1.10 Priority 1

530579 JETMOR 2 69.0 J1 0.49 Priority 1


530594 SMKYP1G1 0.69 1 7.00 Priority 1

530600 SMKYP2G1 0.69 2 22.00 Priority 1

530603 LACROS 3 115. L1 0.34 Priority 1



530624 ST JOHN3 115. J5 1.19 Priority 1

530624 ST JOHN3 115. S2 0.42 Priority 1



530685 LARNED3 115. L1 5.66 Priority 1




530690 PRWINDG1 0.69 1 21.00 Priority 1

531005 BLKWLWD_WTG10.69 1 2.00 Priority 1

531447 HOLCGEN1 22.0 1 372.00 Priority 1

531459 S2 GEN 1 13.8 2 97.00 Priority 1

532653 JEC U3 26.0 1 765.00 Priority 1

532663 LEC U5 24.0 1 342.29 Priority 1

532694 HEC U4 18.0 1 162.00 Priority 1

532721 EEC U1 16.0 1 150.00 Priority 1

532722 EEC U2 24.0 1 370.00 Priority 1

532725 EEC GT3 18.0 1 150.00 Priority 1

532731 GEC U1 12.5 1 35.00 Priority 1

532732 GEC U2 12.5 1 53.00 Priority 1

532733 GEC U3 14.4 1 95.00 Priority 1

532734 GEC U4 14.4 1 90.00 Priority 1

532740 EMPEC121 13.8 1 45.00 Priority 1

532740 EMPEC121 13.8 2 45.00 Priority 1

532741 EMPEC341 13.8 3 45.00 Priority 1

532741 EMPEC341 13.8 4 45.00 Priority 1

532742 EMPEC5 1 18.0 5 130.00 Priority 1

532743 EMPEC6 1 18.0 6 125.00 Priority 1

532744 EMPEC7 1 18.0 7 125.00 Priority 1

532887 CLAYGEN1 13.2 3 5.00 Priority 1

532887 CLAYGEN1 13.2 6T 5.00 Priority 1

532982 OXFORD 4 138. 1 1.50 Priority 1

532982 OXFORD 4 138. 2 1.50 Priority 1

533152 CIRCLVL3 115. 13 3.00 Priority 1


533169 NTHLAND3 115. 1 4.50 Priority 1

533337 SENECA 3 115. 10 1.50 Priority 1

533337 SENECA 3 115. 11 2.50 Priority 1

533337 SENECA 3 115. 12 4.00 Priority 1

533376 SALINA 3 115. 6 3.00 Priority 1

533480 MUSCOTA2 69.0 2 0.50 Priority 1


533560 WELLING2 69.0 5 20.00 Priority 1


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5-7


533561 WINFLD 2 69.0 1 10.00 Priority 1

533582 AUGUSTA2 69.0 N1 6.00 Priority 1

533637 IOLA 2 69.0 1 5.00 Priority 1

533637 IOLA 2 69.0 10 5.00 Priority 1

533662 CGENSUB2 69.0 14 42.00 Priority 1

533665 CHANP3 2 69.0 10 7.00 Priority 1

533665 CHANP3 2 69.0 11 7.00 Priority 1

533665 CHANP3 2 69.0 12 6.00 Priority 1

533665 CHANP3 2 69.0 13 6.00 Priority 1

533761 GIRARD 2 69.0 4 1.50 Priority 1

533761 GIRARD 2 69.0 7 2.50 Priority 1

539653 CIM-PLT1 13.8 1 58.00 Priority 1

539670 FTDODGP1 15.0 4 116.80 Priority 1

541162 DOGWDSTG 18.0 1 150.00 Priority 1

Total Tripped MW 11297.53

Table 5-3: Generators with Non-responding Governors for SPP+AECI Island.

Bus # Bus Name ID Maximum MW

514806 SOONER2G 20.0 1 523.00

515225 MUSKOG5G 18.0 1 500.00

515226 MUSKOG6G 24.0 1 506.00

515266 AES 1G 13.8 1 158.00

532751 WCGS U1 25.0 1 1283.00

547648 OZD312 1 4.60 1 4.00

547648 OZD312 1 4.60 3 4.00

547648 OZD312 1 4.60 4 4.00

547648 OZD312 1 4.60 2 4.00

645001 FT CAL1G 22.0 1 507.00

Total Capability MW 3493.00

Table 5-4: Summary of Shunts Switching in SPP+AECI Island.

Bus # Bus Name Area # Area ID Nominal MVAr

New Original

300079 5FREDTN 161. 330 AECI 37.13 0.00

300349 2SRIVER 69.0 330 AECI 9.00 0.00

511959 BUFFCK1 34.5 520 AEPW 0.00 16.00

531450 HOLCTER1 13.8 532 SUNC -50.00 0.00

531468 SPERTER1 13.8 532 SUNC -50.00 0.00

Total MVAr -53.87 16.00

5.2 Frequency Simulation Results

For this island, all involved elements are tripped right at the beginning of the time-domain

simulation. Bus voltage magnitudes and bus frequencies of the island are plotted in Figure 5-1

and Figure 5-2, respectively. The monitored buses include all 138 kV and higher tension buses,

SPP 2014 UFLS Study


5-8

as well as the generator and step-up transformer buses that are designated for V/Hz

computations. Voltage magnitude behavior appears reasonable and there is no frequency criteria

violation. The oscillations in the frequency plot have all more than 3% damping.

For the lower kV levels, however, some low-voltage magnitudes were observed which do not

cause any problem during simulations and were thus ignored. Note that the under-voltage

phenomenon is different from that of under-frequency and usually does not have a significant

effect on the latter, which is further demonstrated for the second island in the next section.

A summary of the island various quantities, load sheds in the involved areas, generators tripped

by protective relays, and frequency statistics are presented in Table 5-5 through Table 5-8. Note

that during the time-domain simulations (i.e., after the island was formed) no transmission line

tripping occurred, due to angular instability or any other reason.

Table 5-5: SPP+AECI Island Summary.

SPP+AECI Total Summary MW %

Island Load 55309.87 97.65

Island Losses 1331.75 2.35

Island Load and Losses 56641.62 100.00

Tripped Import 2894.76 5.11

Island Generation before Tripping 53746.86 94.89

Tripped Generation 11297.53 19.95

Island Remaining Generation 42449.33 74.94

Island Imbalance 14192.29 25.06

Shed Generation by Protection 401.10 0.71

Shed Load by UFLS Relays 12421.19 21.93

Table 5-6: SPP+AECI Island Load Sheds by Area.

Area # Area ID MW Shed MW Remaining

330 AECI 570.62 4020.63

515 SWPA 138.63 873.40

520 AEPW 2012.82 8376.10

523 GRDA 288.54 763.14

524 OKGE 1481.23 5122.22

525 WFEC 347.58 1132.17

526 SPS 1486.79 4711.20

527 OMPA 89.23 283.16

531 MIDW 37.15 393.50

534 SUNC 292.48 977.95

536 WERE 1440.14 4623.37

540 GMO 637.54 1387.22

541 KCPL 593.36 3054.20

542 KACY 249.00 305.03

544 EMDE 252.83 904.17

545 INDN 55.82 255.18

546 SPRM 187.37 585.72

640 NPPD 1134.91 2641.90

SPP 2014 UFLS Study


5-9


645 OPPD 892.52 1956.53

650 LES 232.61 521.89

SPP+AECI 12421.17 42888.68

Table 5-7: Generators Tripped by Under-frequency Relays in SPP+AECI Island.

Bus # Bus Name ID MW Generation @ Time (s)

641089 EGYCTR2G 18.0 2 248.00 1.14

546723 NM CT4 1 15.0 1 45.00 1.42

642067 PLATTE1G 13.8 1 108.10 1.61


Table 5-8: Frequency Summary of SPP+AECI Island.

SPP+AECI Frequency Hz @ Time (s)

Minimum Bus Frequency 58.36 1.26

Maximum Bus Frequency 60.07 7.17

Steady-State Island Frequency 59.81 50

SPP 2014 UFLS Study


5-10

Figure 5-1: Bus Voltage Magnitudes of SPP+AECI Island.

Figure 5-2: Bus Frequencies of SPP+AECI Island.

SPP 2014 UFLS Study


5-11

5.3 Sensitivity of an Entity with Peak Load under 75 MW

Entities with their total peak load under 25 MW are not expected to participate in the SPP UFLS

plan (already removed from the relay list). It is being suggested that entities whose total peak

load is under 75 MW can disarm their UFLS relays and not participate in the plan, as well. As a

result, the UFLS relay of the load listed in Table 5-9 was removed to evaluate its effect. The

results are summarized in Table 5-10. The total load shed is only 17 MW less and no

measureable effect on other results was observed.

Table 5-9: Disarmed Entity in SPP+AECI Island for Sensitivity Study.

Entity Area Bus Total Load

(MW)

Available for

Shedding (MW)

Carthage Water & Light 525 (WFEC) 505490 (CARTHG 2 69.0) 69.0 21.0

Table 5-10: SPP+AECI Island Load Sheds by Area – Sensitivity.


330 AECI 570.62 4020.63

515 SWPA 121.63 890.39

520 AEPW 2012.82 8376.10

523 GRDA 288.54 763.14

524 OKGE 1481.23 5122.22

525 WFEC 347.58 1132.17

526 SPS 1486.79 4711.20

527 OMPA 89.23 283.16

531 MIDW 37.15 393.50

534 SUNC 292.48 977.95

536 WERE 1440.14 4623.37

540 GMO 637.54 1387.22

541 KCPL 593.36 3054.20

542 KACY 249.00 305.03

544 EMDE 252.83 904.17

545 INDN 55.82 255.18

546 SPRM 187.37 585.72

640 NPPD 1134.91 2641.90

645 OPPD 892.52 1956.53

650 LES 232.61 521.89

SPP+AECI 12404.17 42905.67

5.4 Volts per Hertz Assessment

V/Hz ratio is calculated for all individual generating units of the island greater than 20 MVA or

those units at a generating facility greater than 75 MVA. The V/Hz ratio at high voltage bus of

each GSU transformer is also computed. The analysis is performed using bus voltage and

frequency results of the 100-second simulation.

SPP 2014 UFLS Study


5-12

The V/Hz computations showed no violation for this island, as indicated in Table 5-11.

Furthermore, the sensitivity case showed no change in V/Hz situation.

Table 5-11: SPP+AECI Island V/Hz Results.

Bus # Bus Name Area

#

Area

ID

V/Hz Duration

(s) Maximum Minimum Steady-State

Criteria 1 1.180 2.0

None

Criteria 2 1.100 45

None

SPP 2014 UFLS Study


6-1

6. Island of SPP+AECI+WAPA

6.1 Scenario Descriptions

The ties that are tripped to create this island and the generators that are disconnected to produce

the proper imbalance are listed in Table 6-1 and Table 6-2, respectively. SPP provided a list of

candidate generators for tripping ranked with priority 1 and priority 2; the units with priority 1

are those preferred to be shed first. The tripped units were chosen from the first priority set as

much as possible. From the second priority list only those units that were experiencing instability

were included. Moreover, four units in area 515 (SWPA), totaling to 383.3 MW, were included

due to their instability (no unit in this area was designated by SPP).

Generators with non-responding governors, as provided by SPP, are also listed in Table 6-3.

Furthermore, some available switchable shunts were moved, as summarized in Table 6-4, to

prevent extreme low/high voltages observed. In particular, area 652 (WAPA) was experiencing a

voltage collapse without such switching. Note that such switching would normally take place

within the actual islanding process. The list is intentionally kept to a minimum since it is not

possible to predict exactly which shunts will move in practice.

Table 6-1: Branch Tripping for SPP+AECI+WAPA Island.

1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

300030 8GPDELL 500. 338187 8DELL 500. Z1

300036 5MPLTAP 161. 344923 5LATHROP 161. 1

300038 7ESSEX 345. 344974 7LUTESVIL 345. 1

300041 7FRANKS 345. 344154 7BLAND 345. 1

300041 7FRANKS 345. 344327 7LOOSECRK 345. 1

300044 7MCCRED 345. 345088 7MCCREDIE 345. Z1

300053 5OLDMARS 161. 345024 4MARIES 138. 1

300057 5BARNET 161. 344026 5APCH TP 161. 1

300057 5BARNET 161. 344532 5ELDON 161. 1

300058 5SPALDNG 161. 344697 5HNBL 1 161. 1

300058 5SPALDNG 161. 345034 5MARN TAP 161. 1

300059 5BIG CK 161. 345542 5PT.PRAIR 161. 1

300059 5BIG CK 161. 345941 5WARENTN 161. 1

300061 5BOONE 161. 343014 5GRINDSTN 161. 1

300063 5CALIF 161. 344233 5CALIF UE 161. 1

300065 5CAMDTP 161. 344257 5CAMDEN UE 161. 1

300075 5ESSEX 161. 345790 5STODDARD 161. 1

300077 5FLETCH 161. 344179 5BR CREEK 161. 1

300077 5FLETCH 161. 344566 1FLETCHER 34.5 1

300077 5FLETCH 161. 345511 5PILTSS 161. 1

300077 5FLETCH 161. 345798 5SWEETWTR 161. 1

300079 5FREDTN 161. 344586 5FREDTOWN 161. 1

300079 5FREDTN 161. 345976 5WEDEKN T 161. 1

300083 5GIBSON 161. 338202 5JIMHL 161. 1

300098 5MOCITY 161. 344558 5EX SPRNG 161. 1

300103 5NEWMAD 161. 338201 5PRTGVL 161. 1

300103 5NEWMAD 161. 361261 5TIPTONVL TN161. 1

SPP 2014 UFLS Study


6-2

1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

300106 5NOVELY 161. 344006 5ADAIR3 161. 1

300113 5SRIVER 161. 345437 5PALMYRA 161. 1

300115 5STFRAN 161. 338202 5JIMHL 161. 1

300120 5THMHIL 161. 344004 5ADAIR1 161. 1

300121 5MORLEY 161. 345375 5ORAN 161. 1

300121 5MORLEY 161. 345790 5STODDARD 161. 1

300126 5MOBTAP 161. 345221 5MOBERLY 161. 1

300179 2HAMBRG 69.0 635055 PERCIVL8 69.0 1

300426 2MILTNWY 69.0 630691 MILTON 8 69.0 1

300431 2BATAVI 69.0 630036 JEFF 8 69.0 1

300434 2PRMRST 69.0 630683 DONLSON8 69.0 1

300438 2HARSTP 69.0 630692 BONPRT18 69.0 1

300439 2HENRY 69.0 631106 HENRYCO5 161. 1

300439 2HENRY 69.0 631106 HENRYCO5 161. 2

300446 2PRIMRS 69.0 630690 HOUGHTN8 69.0 1

300448 2SAWYER 69.0 630013 VIELE 8 69.0 1

300448 2SAWYER 69.0 630659 IAAP TAP 69.0 1

300452 2WOOSTR 69.0 630036 JEFF 8 69.0 1

300453 2WPOINT 69.0 630684 WEST PT8 69.0 Z1

300465 2KEOSAQ 69.0 630691 MILTON 8 69.0 1

300465 2KEOSAQ 69.0 630692 BONPRT18 69.0 1

300466 2MARK 69.0 630033 APANOSE8 69.0 1

300467 2OTTUMW 69.0 630409 S OTTUM8 69.0 1

300480 5OFALLON 161. 345091 5MIDR 161. 1

300482 2MORAVA 69.0 630414 MORAVIT8 69.0 Z1

300487 2TRAIL 69.0 630387 ALBIA 8 69.0 1

300493 2BOONE 69.0 343006 2GRINDSTN 69.0 1

300496 2COLMBIA 69.0 343003 2PLANT 69.0 1

300499 5HINTON 161. 343001 5BOLSTAD 161. 1

300500 5HUNTSDL 161. 343004 5PERCHE 161. 1

300500 5HUNTSDL 161. 345409 5OVERTON 161. 1

300501 5MCBAIN 161. 345071 5MCBAIN T 161. 1

300504 2SHAW 69.0 343050 2BOLSTAD2 69.0 1

300506 2SWITZR 69.0 343050 2BOLSTAD2 69.0 1

300593 5COTLE1 161. 344773 5HWY N 161. 1

300593 5COTLE1 161. 345091 5MIDR 161. 1

300595 5CYRENE 161. 345498 5PIKE S 161. 1

300596 5DARDEN 161. 344773 5HWY N 161. 1

300597 5ENON 161. 344535 7ENON 345. 1

300597 5ENON 161. 344630 5GM 161. 1

300597 5ENON 161. 345542 5PT.PRAIR 161. 1

300599 4KISKER 138. 344880 4KISKER T 138. 1

300606 5TROY 161. 344449 5DARD12 161. 1

300606 5TROY 161. 344480 5TROYUE 161. 1

300718 5CLEVCOV 161. 338120 5LEAD HL 161. 1

300756 5STEELE 161. 338200 5HAYTI 161. 1

300756 5STEELE 161. 338804 5BLYN# 161. 1

300858 5SMRSVLEST 161. 345798 5SWEETWTR 161. 1

301101 2COUCH 69.0 338217 2THAY-N 69.0 1

301124 5COXCRK 161. 338215 5THAY-S 161. 1

301144 4PRIDGE 138. 344360 4CLARK O-R 138. 1

301263 2FLETCH 69.0 344566 1FLETCHER 34.5 1

SPP 2014 UFLS Study


6-3

1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

301273 2PILOTK 69.0 345510 5PILTMA 161. 1

301406 8WNEWMADRID 500. 338187 8DELL 500. 1

503912 FULTON 3 115. 338875 3PATMOS# 115. 1

504080 GLENCOE 5 161. 338220 ASH FLT5 161. 1

505418 JONESBO5 161. 338170 5JONES 161. 1

505420 HERGETT5 161. 338170 5JONES 161. 1

505420 HERGETT5 161. 338707 5TRUM-W# 161. 1

505422 GREERSF5 161. 338758 5HEBR-N# 161. 1

505428 SIKESTN5 161. 345203 5MINER 161. 1

505442 WATER V5 161. 338220 ASH FLT5 161. 1

505442 WATER V5 161. 338223 5WATVAL* 161. 1

505448 NORFORK5 161. 338130 5CALCR 161. 1

505448 NORFORK5 161. 338814 5SOLAND# 161. 1

505460 BULL SH5 161. 338110 5HILLTOP 161. 1

505460 BULL SH5 161. 338120 5LEAD HL 161. 1

505460 BULL SH5 161. 338123 5BULLSH* 161. 1

505460 BULL SH5 161. 338813 5MIDWAY# 161. 1

505472 TABLE R5 161. 338099 5GDVIEW 161. 1

505508 DARDANE5 161. 337903 5DARDAN 161. 1

505508 DARDANE5 161. 337904 5RUSL-S 161. 1

505508 DARDANE5 161. 338110 5HILLTOP 161. 1

506932 EUREKA 5 161. 338099 5GDVIEW 161. 1

506932 EUREKA 5 161. 338682 5OSAGE # 161. 1

507195 MAGZREC5 161. 337902 5DANVI 161. 1

507434 SNASHVL4 138. 337672 4MURFRE 138. 1

507460 PRESCOT3 115. 337507 3PRESCT 115. Z1

507760 SW SHV 7 345. 500250 DOLHILL7 345. 1

507765 WALLAKE4 138. 500430 IPAPER 4 138. 1

507788 MINDEN-3 115. 337361 3MINDEN 115. 1

508359 WELSH 7 345. 599892 EASTDC 7 345. DC 15

508809 LONGWD 7 345. 337376 7SAREPT 345. 1

509241 CROCKET7 345. 334028 7GRIMES 345. 1

511456 O.K.U.-7 345. 599891 OKLAUN 7 345. DC 14

515305 FTSMITH8 500. 337909 8ANO 50 500. 1

523853 FINNEY 7345. 599950 LAMAR7 345. 1

524911 ROSEVELT_S 6230. 599955 PNM-DC6 230. Z1

527799 EDDY_NORTH 6230. 599960 EPTNP-D6 230. @1

541201 SIBLEY 7 345. 345408 7OVERTON 345. 1

541241 SEDEAST5 161. 345409 5OVERTON 161. 1

541251 MARYVLE5 161. 635034 CLRNDA 5 161. 1

543060 CAROLTN5 161. 344558 5EX SPRNG 161. 1

543062 SALSBRY5 161. 345221 5MOBERLY 161. 1

547474 OZD312 5 161. 338105 5OMAHA * 161. 1

603023 MALLARD7 115. 603022 SOURIS 7 115. 1

630821 HANCOCK8 69.0 630354 HNCKCAP8 69.0 1

630821 HANCOCK8 69.0 630462 GARNER 8 69.0 1

630821 HANCOCK8 69.0 630464 KLEMME8 69.0 1

630821 HANCOCK8 69.0 631103 HANCOCK5 161. 1

630821 HANCOCK8 69.0 631103 HANCOCK5 161. 2

631069 ANTA TP5 161. 631070 ANITA 5 161. 1

640139 COOPER 3 345. 635017 ATCHSNT3 345. 1

640226 HOSKINS3 345. 635200 RAUN 3 345. 1

SPP 2014 UFLS Study


6-4

1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

640377 TEKAMAH5 161. 635201 RAUN 5 161. 1

645451 S3451 3 345. 635200 RAUN 3 345. 1

645456 S3456 3 345. 635000 CBLUFFS3 345. 1

646206 S1206 5 161. 635001 CBLUFFS5 161. 1

646211 S1211 5 161. 635003 SUB701 5 161. 1

652204 VALLEYC8 69.0 657804 MPC-VCY8 69.0 Z

652296 WARD 4 230. 661053 MANDAN 4 230. 1

652404 DAWSONC7 115. 661032 GLENDCT7 115. 1

652404 DAWSONC7 115. 661056 LEWIS 7 115. 1

652412 MI CTYE7 115. 652219 MI CTYE8 57.0 1

652417 DICKNSN4 230. 652418 DKSN-ND7 115. 1

652417 DICKNSN4 230. 661053 MANDAN 4 230. 1

652421 WILISTN7 115. 661087 RAY JCT7 115. 1

652422 HALIDAY7 115. 661008 BEULAH 7 115. 1

652427 BISMARK7 115. 661029 ESTBMRK7 115. 1

652431 DEVILSL7 115. 620267 DEVIL J7 115. 1

652435 FARGO 4 230. 602006 SHEYNNE4 230. 1

652436 FARGO 7 115. 652203 FARGO 8 69.0 1

652436 FARGO 7 115. 652203 FARGO 8 69.0 2

652437 GRNDFKS4 230. 657755 PRAIRIE4 230. 1

652438 FORMAN 7 115. 620263 FORMN 7 115. 1

652442 GARRISN7 115. 661008 BEULAH 7 115. 1

652443 GRNDFKS7 115. 652202 GRNDFKS8 69.0 1

652443 GRNDFKS7 115. 657706 FALCONR7 115. 1

652448 LAKOTA 7 115. 652205 LAKOTA 8 69.0 1

652451 RICHLND7 115. 661056 LEWIS 7 115. 1

652452 RUGBY 7 115. 659264 RUGBCPC7 115. 1

652503 BLAIR 4 230. 620314 BIGSTON4 230. 1

652522 SUMMIT-7 115. 652326 SUMMIT-9 41.8 1

652523 SIOUXFL4 230. 602004 SPLT RK4 230. 1

652524 SIOUXFL7 115. 603012 LAWRENC7 115. 1

652537 WHITE 3 345. 601007 SPLTRTA3 345. 1

652537 WHITE 3 345. 601031 BRKNGCO3 345. 1

652537 WHITE 3 345. 601031 BRKNGCO3 345. 2

652550 GRANITF4 230. 602007 MINVALY4 230. 1

652550 GRANITF4 230. 602009 MNVLTAP4 230. 1

652550 GRANITF4 230. 619975 GRE-WILLMAR4230. 1

652551 GRANITF7 115. 603030 MINVALY7 115. 1

652551 GRANITF7 115. 620211 CANBY 7 115. 1

652555 MORRIS 7 115. 616002 GRE-JOHNJCT7115. 1

652555 MORRIS 7 115. 620218 MOROTP 7 115. 1

652555 MORRIS 7 115. 652318 MORRIS 9 41.6 1

652555 MORRIS 7 115. 658102 GRANTCO7 115. 1

652560 CRESTON5 161. 631078 WNTRST 5 161. 1

652560 CRESTON5 161. 635038 BROOKST5 161. 1

652564 SIOUXCY3 345. 601008 SPLTRTB3 345. 1

652564 SIOUXCY3 345. 635200 RAUN 3 345. 1

652566 SIOUXCY5 161. 635223 PLYMOTH5 161. 1

652568 CRESTN 8 69.0 630381 SLAKEN 8 69.0 1

652569 CRESTON8 69.0 630385 SLAKES 8 69.0 1

652569 CRESTON8 69.0 630419 ECRESTN8 69.0 1

652574 SIOUXCY8 69.0 635224 PLYMOTH8 69.0 1

SPP 2014 UFLS Study


6-5

1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

656047 MIDWAY8 69.0 636301 FLOYD 8 69.0 1

656051 NEWHAMPM G 69.0 680317 WAPSI 69.0 1

656053 OAKWODTA8 69.0 636301 FLOYD 8 69.0 1

656063 PLAINFD8 69.0 636283 PLNFDJT8 69.0 1

656087 BREMER CO5 161. 636200 BLKHAWK5 161. 1

656087 BREMER CO5 161. 636300 FLOYD 5 161. 1

656159 SHRWOOD8 69.0 635328 AUBRN 8 69.0 1

656159 SHRWOOD8 69.0 636091 RKWLCT+8 69.0 1

656193 HAMPTON8 69.0 636315 HAMPTNW8 69.0 1

656199 MECSHDFT8 69.0 636316 SHEFFLD8 69.0 1

656201 SHEFFLD5 161. 631048 EMERY 5 161. 1

656207 HAMPTONTAP5 161. 636230 FRANKLN5 161. 1

656241 WEAKLEND8 69.0 635324 WSTSIDE8 69.0 1

656241 WEAKLEND8 69.0 635329 WSIDETP8 69.0 1

656249 TOYNE8 69.0 635322 CAROL S8 69.0 1

656249 TOYNE8 69.0 635325 TEMPLTN8 69.0 1

656283 DRAGER5 161. 631074 GR JCT 5 161. 1

656283 DRAGER5 161. 635320 CARROLL5 161. 1

656289 GRNDYCTR8 69.0 630860 DIKEMORRISN869.0 1

656299 TRAERTAP8 69.0 630027 TRAER 8 69.0 1

656301 WELSBRG G 69.0 631008 WELSBRG5 161. 1

656307 REINBECKTAP 69.0 630861 REINBECK8 69.0 1

656309 WELBRGEASTT869.0 630862 WELSBRGDIST869.0 1

656353 HOPE5 161. 636001 WEBSTER5 161. 1

656355 HUMBOLDT8 69.0 636070 HMBLTTP8 69.0 1

656369 WEBSTER8 69.0 636001 WEBSTER5 161. 1

656415 ALTA TAP8 69.0 635281 BVISTA 8 69.0 1

656423 BURT5 161. 631103 HANCOCK5 161. 1

656451 EBURGJCT 69.0 636102 EBURG E8 69.0 1

656467 FOXRUN8 69.0 630011 PETERSN8 69.0 1

656467 FOXRUN8 69.0 630353 BROOKE 8 69.0 1

656483 HANOVRTP8 69.0 635341 SAC 8 69.0 1

656515 MECJCT8 69.0 636100 EMTSBGS8 69.0 1

656519 MILENELS8 69.0 635282 STMLK E8 69.0 1

656521 MILFORD8 69.0 630023 TRIBOJI8 69.0 1

656529 OSGOOD G 69.0 636100 EMTSBGS8 69.0 1

656531 PELICAN8 69.0 656427 CBGAR T8 69.0 1

656531 PELICAN8 69.0 656542 RANGE 8 69.0 1

656567 TRUESDAL8 69.0 635281 BVISTA 8 69.0 1

656570 WISDOM5 161. 631183 CAYLER5 161. 1

656570 WISDOM5 161. 635280 BVISTA 5 161. 1

656573 WISDOM G 69.0 635373 MIDAMER8 69.0 1

656583 ALTAMUNITAP869.0 635279 AURELIA T8 69.0 1

656583 ALTAMUNITAP869.0 635281 BVISTA 8 69.0 1

656597 MNTGMYT8 69.0 630023 TRIBOJI8 69.0 1

656597 MNTGMYT8 69.0 630485 MNTGMY8 69.0 1

656597 MNTGMYT8 69.0 656435 DIAMNDLK8 69.0 1

656753 ALDEN8 69.0 630859 ALDNBUCKEYE869.0 1

656761 ELDORA8 69.0 630839 OTTERCREEK8 69.0 1

656769 FARM_TAP8 69.0 630341 IAFINDP8 69.0 1

656775 IFE8 69.0 630341 IAFINDP8 69.0 1

656781 PLEASANT8 69.0 630839 OTTERCREEK8 69.0 1

SPP 2014 UFLS Study


6-6

1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

656783 ROLAND8 69.0 630710 FERNALD8 69.0 1

656791 RADCLIFF8 69.0 630840 HUBBRDRURAL869.0 1

656793 NNG-HUBBARD869.0 630842 HUBBRDPUMPT869.0 1

656843 BLAIRSBU8 69.0 636236 WALL LK8 69.0 1

656887 SWEAZY G 69.0 636051 WRIGHT 8 69.0 1

656891 TOUCHSTN8 69.0 630460 NGARNER8 69.0 1

656903 WILLEMSN8 69.0 630469 BELMNDJ8 69.0 1

656903 WILLEMSN8 69.0 636236 WALL LK8 69.0 1

656975 SAC CITY8 69.0 635347 SACCITY8 69.0 1

656979 SACJCT8 69.0 635347 SACCITY8 69.0 1

656981 SCHALLER8 69.0 635341 SAC 8 69.0 1

657707 CALEDON7 115. 657780 CALEDONT 115. 1

657759 PICKERT4 230. 657923 PICKERT8 69.0 1

Tertiary 620167 PICKERT9 41.6

658068 MARSHAL7 115. 603046 LYON CO7 115. 1

658076 MMU SW 7 115. 603010 LKYNKTN7 115. 1

659106 LELANDO4 230. 615901 GRE-STANTON4230. 1

659113 VOLTAIR7 115. 615348 GRE-MCHENRY7115. 1

659139 NESET 7 115. 661085 TIOGA4 7 115. 1

659149 THORNE CP7115. 659694 ROLETTE7 115. 1

659283 NBCS8 ZLND1G13.8 661095 WISHEK 7 115. 1

659308 KENASTON 7115. 661052 KENMARE7 115. 1

659615 BARRBUTE-MW7115. 659145 GRENORA7 115. 1

659627 FLATLAKE-SH7115. 659145 GRENORA7 115. 1

659891 K336LINCOLN869.0 635040 AVOCA 8 69.0 1

659901 EAGLE 8 69.0 635385 HUDSON 8 69.0 1

659901 EAGLE 8 69.0 635391 IRETONT8 69.0 1

659909 J3CHEROKEE 869.0 635272 MERIDEN8 69.0 1

659909 J3CHEROKEE 869.0 635361 LT SX 8 69.0 1

659910 J4IDAGR8 69.0 635307 IDAGROV8 69.0 1

659913 J7PANMA8 69.0 635040 AVOCA 8 69.0 1

659914 J8ATLAN8 69.0 635046 TEAKWOOD 8 69.0 1

659914 J8ATLAN8 69.0 638051 ATLNTIC8 69.0 1

659916 J10KMBL8 69.0 635327 EXIRA 8 69.0 1

659919 J13WDBN8 69.0 635082 LOGAN 8 69.0 1

659922 K10215A8 69.0 635236 SALIX 8 69.0 1

659923 K10225A8 69.0 635236 SALIX 8 69.0 1

659955 K213HOSPERS869.0 635371 HOSPERS8 69.0 1

659956 K208ARCHER 869.0 635371 HOSPERS8 69.0 1

659963 K408AFTON 869.0 635272 MERIDEN8 69.0 1

659977 K218ROCKVAL869.0 635381 RKVALTT8 69.0 1

659990 K121MAPLETM869.0 635301 MONONA 8 69.0 1

660000 ABDNJCT7 115. 661027 ELLENDL7 115. 1

660004 MITCHEL7 115. 603009 GRANT 7 115. 1

661004 BAKER 4 230. 661005 BAKER 7 115. 1

Tertiary 661901 BAKER 9 13.8

661038 GLENHAM4 230. 661035 GLENHAM7 115. 1

Tertiary 661600 GLENHAM9 41.6

661038 GLENHAM4 230. 661035 GLENHAM7 115. 2

Tertiary 661600 GLENHAM9 41.6

661047 HETINGR4 230. 661048 HETINGR7 115. 1

Tertiary 661902 HETINGR9 13.8

SPP 2014 UFLS Study


6-7

1st Bus # 1

st Bus Name 2

nd Bus # 2

nd Bus Name ID

661084 TIOGA4 4 230. 661085 TIOGA4 7 115. 1

Tertiary 661900 TIOGA4 9 13.8

661084 TIOGA4 4 230. 672603 BDV 4 230. 1

Total Tripped MW Import 1552.73

Table 6-2: Generator Tripping for SPP+AECI+WAPA Island.


300001 1THLG1 20.0 1 150.00 Priority 1

300002 1THLG2 22.0 1 217.43 Priority 1

300010 1STFRG1 16.0 1 210.00 Priority 1

505432 SIKGEN 1 13.8 1 235.00 Tripped due to instability




509394 FLINTCR1 22.0 1 514.00 Priority 1

509404 WELSH1-1 18.0 1 525.00 Priority 1

509405 WELSH2-1 18.0 1 525.00 Priority 1

509406 WELSH3-1 18.0 1 525.00 Priority 1

511840 NES3-1 22.0 1 400.00 Priority 1

511842 RSS1-1 24.0 1 350.00 Priority 1

512686 SALINA 5 161. 1 41.11 Priority 1

512686 SALINA 5 161. 2 41.11 Priority 1

512686 SALINA 5 161. 3 41.11 Priority 1

512689 GRDA15-1 22.8 1 435.00 Priority 1

512711 SALINA2 161. 4 36.00 Priority 1

512711 SALINA2 161. 5 36.00 Priority 1

512711 SALINA2 161. 6 36.00 Priority 1

514001 CRSRD-WTG1 0.69 1 21.00 Priority 1



514013 MINCO-WTG1 0.69 1 9.00 Priority 1

514084 OUSPRT-WTG1 0.69 1 9.00 Priority 1




514805 SOONER1G 22.0 1 515.00 Priority 1

515040 SEMINL1G 20.9 1 349.65 Priority 1

515223 MUSKOG4G 18.0 1 504.00 Priority 1

515362 SLPBRAD-WTG10.69 1 11.00 Priority 1

515479 CHSHMVE1 34.5 1 11.50 Priority 1

515484 CHSHMVW1 34.5 1 18.00 Priority 1

515564 ORIGIN11 34.5 1 3.50 Priority 1

515565 ORIGIN21 34.5 1 3.50 Priority 1

515606 CANDN11 0.69 1 10.00 Priority 1

515790 FPLMRLND-WG10.69 1 4.80 Priority 1

520947 HUGO1 23.4 1 440.00 Priority 1

522875 LP-BRANDON 269.0 1 20.00 Priority 1




SPP 2014 UFLS Study


6-8





523183 SPEARMAN 134.5 1 0.62 Priority 1

523255 ETTER 134.5 1 0.98 Priority 1

523255 ETTER 134.5 2 1.36 Priority 1

523301 MOORE_E 113.2 1 1.23 Priority 1

523301 MOORE_E 113.2 3 1.17 Priority 1

523307 DUMAS WTG 0.69 1 4.28 Priority 1



523354 HERRING 134.5 2 0.36 Priority 1

523815 LLANO_WND 3115. 1 6.77 Priority 1

523866 CHANNING 134.5 1 0.18 Priority 1

523923 CARSON_SUB 113.8 1 4.89 Priority 1



523973 HARRNGTON3 124.0 1 339.00 Priority 1

524285 WILDORA_GEN10.69 1 30.07 Priority 1

524287 GS-PHWD_GEN10.69 1 2.00 Priority 1

524295 SPNSPUR_WND10.69 1 16.10 Priority 1

524485 CAPROCK_WND134.5 1 7.60 Priority 1






525942 HENDRICKS 122.9 1 0.82 Priority 1

526332 JONES_2 122.0 1 225.02 Priority 1

527163 MUSTANG_3 122.0 1 164.00 Priority 1



528224 HOPI_SUB 112.5 1 7.00 Priority 1

528331 ASGI10-010 113.8 1 8.40 Priority 1

528331 ASGI10-010 113.8 2 8.40 Priority 1

528331 ASGI10-010 113.8 3 8.40 Priority 1

528332 WILDCAT_WND134.5 1 2.00 Priority 1

528490 MONUMENT 112.5 1 7.00 Priority 1

528504 LEA_ROAD 112.5 1 7.00 Priority 1

528546 S_JAL 112.5 1 7.00 Priority 1

528560 DOLLARHIDE 112.5 1 7.00 Priority 1

530555 COLBY 3 115. C3 0.22 Priority 1

530555 COLBY 3 115. C6 3.50 Priority 1

530555 COLBY 3 115. C7 3.60 Priority 1

530555 COLBY 3 115. C8 2.00 Priority 1

530575 N ELWD 2 69.0 E1 1.90 Priority 1

530575 N ELWD 2 69.0 E2 1.10 Priority 1



530594 SMKYP1G1 0.69 1 7.00 Priority 1

530600 SMKYP2G1 0.69 2 22.00 Priority 1


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6-9




530624 ST JOHN3 115. J5 1.19 Priority 1








530690 PRWINDG1 0.69 1 21.00 Priority 1

531005 BLKWLWD_WTG10.69 1 2.00 Priority 1

531447 HOLCGEN1 22.0 1 372.00 Priority 1

531459 S2 GEN 1 13.8 2 97.00 Priority 1

532653 JEC U3 26.0 1 765.00 Priority 1

532663 LEC U5 24.0 1 342.29 Priority 1

532694 HEC U4 18.0 1 162.00 Priority 1

532721 EEC U1 16.0 1 150.00 Priority 1

532722 EEC U2 24.0 1 370.00 Priority 1

532725 EEC GT3 18.0 1 150.00 Priority 1

532731 GEC U1 12.5 1 35.00 Priority 1

532732 GEC U2 12.5 1 53.00 Priority 1

532733 GEC U3 14.4 1 95.00 Priority 1

532734 GEC U4 14.4 1 90.00 Priority 1

532740 EMPEC121 13.8 1 45.00 Priority 1

532740 EMPEC121 13.8 2 45.00 Priority 1

532741 EMPEC341 13.8 3 45.00 Priority 1

532741 EMPEC341 13.8 4 45.00 Priority 1

532742 EMPEC5 1 18.0 5 130.00 Priority 1

532743 EMPEC6 1 18.0 6 125.00 Priority 1

532744 EMPEC7 1 18.0 7 125.00 Priority 1

532887 CLAYGEN1 13.2 3 5.00 Priority 1

532887 CLAYGEN1 13.2 6T 5.00 Priority 1

532982 OXFORD 4 138. 1 1.50 Priority 1

532982 OXFORD 4 138. 2 1.50 Priority 1



533169 NTHLAND3 115. 1 4.50 Priority 1

533337 SENECA 3 115. 10 1.50 Priority 1

533337 SENECA 3 115. 11 2.50 Priority 1

533337 SENECA 3 115. 12 4.00 Priority 1

533376 SALINA 3 115. 6 3.00 Priority 1





533561 WINFLD 2 69.0 1 10.00 Priority 1

533582 AUGUSTA2 69.0 N1 6.00 Priority 1

533637 IOLA 2 69.0 1 5.00 Priority 1

533637 IOLA 2 69.0 10 5.00 Priority 1

533662 CGENSUB2 69.0 14 42.00 Priority 1

533665 CHANP3 2 69.0 10 7.00 Priority 1

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6-10


533665 CHANP3 2 69.0 11 7.00 Priority 1

533665 CHANP3 2 69.0 12 6.00 Priority 1

533665 CHANP3 2 69.0 13 6.00 Priority 1

533761 GIRARD 2 69.0 4 1.50 Priority 1

533761 GIRARD 2 69.0 7 2.50 Priority 1

539653 CIM-PLT1 13.8 1 58.00 Priority 1

539670 FTDODGP1 15.0 4 116.80 Priority 1

541152 SIBLEY#2 13.2 2 50.00 Priority 1

658000 EXIRA 1G 13.8 1 44.70 Priority 1

658001 EXIRA 2G 13.8 2 43.30 Priority 1

660001 ABDNSBT7 115. 2 52.00 Priority 1

660003 HURONWP7 115. 2 10.00 Priority 1

660003 HURONWP7 115. 3 40.00 Priority 1

660006 YKNTJCT7 115. 1 13.00 Priority 1

660010 TITAN WIND W0.69 1 5.00 Priority 1

531201 RUBART 1 13.8 1 9.00 Priority 2

531201 RUBART 1 13.8 2 9.00 Priority 2

531201 RUBART 1 13.8 3 9.00 Priority 2

531201 RUBART 1 13.8 4 9.00 Priority 2

531201 RUBART 1 13.8 5 9.00 Priority 2

531201 RUBART 1 13.8 6 9.00 Priority 2

531202 RUBART 2 13.8 7 9.00 Priority 2

531202 RUBART 2 13.8 8 9.00 Priority 2

531202 RUBART 2 13.8 9 9.00 Priority 2

531202 RUBART 2 13.8 10 9.00 Priority 2

531202 RUBART 2 13.8 11 9.00 Priority 2

531202 RUBART 2 13.8 12 9.00 Priority 2

652414 FTPECK4G 13.8 4 37.00 Priority 2

652415 FTPECK5G 13.8 5 37.00 Priority 2

652457 GARISN1G 13.8 1 100.00 Priority 2





652491 IRVSIMM7 115. 1 2.00 Priority 2

652542 BGBND12G 13.8 1 64.00 Priority 2

652542 BGBND12G 13.8 2 64.00 Priority 2

652543 BGBND34G 13.8 3 64.00 Priority 2

652543 BGBND34G 13.8 4 64.00 Priority 2

652544 BGBND56G 13.8 5 64.00 Priority 2

652544 BGBND56G 13.8 6 63.00 Priority 2

652545 BGBND78G 13.8 7 44.20 Priority 2

652545 BGBND78G 13.8 8 44.30 Priority 2

652546 FTRDL12G 13.8 1 45.00 Priority 2

652546 FTRDL12G 13.8 2 45.00 Priority 2

652547 FTRDL34G 13.8 3 45.00 Priority 2

652547 FTRDL34G 13.8 4 45.00 Priority 2

652548 FTRDL56G 13.8 5 44.00 Priority 2

652548 FTRDL56G 13.8 6 44.00 Priority 2

652556 OAHE2-3G 13.8 2 97.00 Priority 2

652556 OAHE2-3G 13.8 3 97.00 Priority 2

652557 OAHE4-5G 13.8 4 97.00 Priority 2

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6-11


652557 OAHE4-5G 13.8 5 97.00 Priority 2

652558 OAHE6-7G 13.8 6 97.00 Priority 2

652558 OAHE6-7G 13.8 7 97.00 Priority 2

652559 OAHE 1G 13.8 1 69.58 Priority 2

652575 GAVINS1G 13.8 1 34.00 Priority 2



659234 DGCX4 9 13.8 BG -30.00 Priority 2

659270 CULBERTSON1G13.8 2 5.50 Priority 2

659276 NBCS7 1G 12.5 1 5.50 Priority 2


Table 6-3: Generators with Non-responding Governors for SPP+AECI+WAPA Island.

Bus # Bus Name ID Maximum MW

514806 SOONER2G 20.0 1 523.00

515225 MUSKOG5G 18.0 1 500.00

515226 MUSKOG6G 24.0 1 506.00

515266 AES 1G 13.8 1 158.00

532751 WCGS U1 25.0 1 1283.00

547648 OZD312 1 4.60 1 4.00

547648 OZD312 1 4.60 2 4.00

547648 OZD312 1 4.60 3 4.00

547648 OZD312 1 4.60 4 4.00

645001 FT CAL1G 22.0 1 507.00

652491 IRVSIMM7 115. 1 2.00

658000 EXIRA 1G 13.8 1 44.70

658001 EXIRA 2G 13.8 2 43.30

658084 MPSCENT7 115. 1 10.80

659103 ANTEL31G 24.0 1 465.00

659107 ANTEL32G 24.0 2 465.00

659110 LELAN41G 22.0 1 199.10

659111 LELAN32G 20.0 2 440.00

659118 LARAM31G 24.0 1 605.00

659129 NBCS5 KLDR1G13.8 1 5.50

659169 NBCS12 1G13.8 1 5.50

659270 CULBERTSON1G13.8 2 5.50

659276 NBCS7 1G 12.5 1 5.50

659277 NBCS9 1G 12.5 1 5.50

659278 NBCS101G 12.5 1 5.50

659279 NBCS111G 12.5 1 5.50

659285 DEERCREEK 1G13.8 1 294.00

660001 ABDNSBT7 115. 2 52.00

660003 HURONWP7 115. 3 40.00

Total Capability MW 6192.40

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6-12

Table 6-4: Summary of Shunts Switching in SPP+AECI+WAPA Island.


New Original

300079 5FREDTN 161. 330 AECI 37.13 0.00

300349 2SRIVER 69.0 330 AECI 9.00 0.00

511959 BUFFCK1 34.5 520 AEPW 0.00 16.00

531450 HOLCTER1 13.8 532 SUNC -50.00 0.00

531468 SPERTER1 13.8 532 SUNC -50.00 0.00

630821 HANCOCK8 69.0 652 WAPA 14.40 0.00

652201 GRNDFKS9 12.5 652 WAPA -30.00 0.00

652221 BELFELD9 13.8 652 WAPA 0.00 -30.00

652239 WATERT29 13.2 652 WAPA 0.00 -30.00

652240 WATERT39 13.2 652 WAPA 0.00 -30.00

652247 MAURINE9 13.8 652 WAPA 0.00 -20.00

652267 NUNDRWD9 13.8 652 WAPA 0.00 -49.50

652273 FTTHMP19 13.8 652 WAPA -34.50 0.00

652274 FTTHMP29 13.8 652 WAPA -19.50 0.00

652281 HURON419 13.3 652 WAPA 0.00 -33.64

652282 HURON429 13.3 652 WAPA 0.00 -33.64

652292 GRANITF29 13.8 652 WAPA 0.00 -50.00

652293 WHITE 9 13.8 652 WAPA -30.00 0.00

652411 MI CTYE4 230. 652 WAPA 30.00 85.42

652434 FARGOSVC 13.2 652 WAPA -90.00 0.00

652474 AURORA 7 115. 652 WAPA 20.00 0.00

652475 BONESTL7 115. 652 WAPA 10.80 0.00

652479 MARTIN 7 115. 652 WAPA 21.43 0.00

652490 RAPIDCY7 115. 652 WAPA 0.00 34.98

652494 WINNER 7 115. 652 WAPA 10.00 0.00

652502 BERSFRD7 115. 652 WAPA 15.00 0.00

652550 GRANITF4 230. 652 WAPA 0.00 81.40

652583 DENISON8 69.0 652 WAPA 60.00 0.00

656159 SHRWOOD8 69.0 652 WAPA 19.20 0.00

656301 WELSBRG G 69.0 652 WAPA 15.60 0.00

656355 HUMBOLDT8 69.0 652 WAPA 30.60 0.00

656425 BURT8 69.0 652 WAPA 19.80 0.00

656443 DOVER8 69.0 652 WAPA 7.20 0.00

656529 OSGOOD G 69.0 652 WAPA 15.60 0.00

656531 PELICAN8 69.0 652 WAPA 19.20 0.00

656575 WLNGFRD8 69.0 652 WAPA 12.00 0.00

656783 ROLAND8 69.0 652 WAPA 7.20 0.00

659166 DUNNING7 115. 652 WAPA 20.00 10.00

659167 STEGALLM 13.8 652 WAPA 0.00 -25.00

659271 RCDC EAST 4230. 652 WAPA -30.00 0.00

659303 RCDC WEST 4230. 652 WAPA 0.00 -30.00

659307 SWMINOT CP7115. 652 WAPA 10.00 0.00

659604 BELDEN -MW7115. 652 WAPA 15.00 7.50

659607 ENEWTWN -MW7115. 652 WAPA 12.00 6.00

660000 ABDNJCT7 115. 652 WAPA 10.80 0.00

660001 ABDNSBT7 115. 652 WAPA 7.20 0.00

660004 MITCHEL7 115. 652 WAPA 14.40 4.80

660005 TRIPP 7 115. 652 WAPA 5.40 0.00

660006 YKNTJCT7 115. 652 WAPA 10.80 0.00

660007 MENNOJT7 115. 652 WAPA 5.40 2.70

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6-13


New Original

660008 MITCLNW7 115. 652 WAPA 5.40 0.00

661038 GLENHAM4 230. 652 WAPA 0.00 -20.00

Total MVAr 156.56 -102.98

6.2 Frequency Simulation Results

For this island, all involved elements are tripped right at the beginning of the time-domain

simulation. Bus voltage magnitudes and bus frequencies of the island are plotted in Figure 6-1

and Figure 6-2, respectively. The monitored buses include all 138 kV and higher tension buses,

as well as the generator and step up transformer buses that are designated for V/Hz

computations. There is no frequency criteria violation. The oscillations in the frequency plot

have all more than 3% damping. Voltage magnitudes behave, except for being very low at

several buses in area 652 (WAPA). For the lower kV levels some low-voltage magnitudes were

observed as well. These low voltages do not cause any problem during simulations and were thus

ignored. Note that the under-voltage phenomenon is different from that of under-frequency; the

two phenomena usually do not have a significant effect on each other (as long as they do not

cause a complete collapse).

A summary of the island various quantities, load sheds in the involved areas, generators tripped

by protective relays, and frequency statistics are presented in Table 6-5 through Table 6-8. Note

that during the time-domain simulations (i.e., after the island was formed) no transmission line

tripping occurred, due to angular instability or any other reason.

Table 6-5: SPP+AECI+WAPA Island Summary.

SPP+AECI+WAPA Total Summary MW %

Island Load 58952.30 97.50

Island Losses 1513.13 2.50

Island Load and Losses 60465.43 100.00

Tripped Import 1569.19 2.60

Island Generation before Tripping 58896.25 97.40

Tripped Generation 13561.61 22.43

Island Remaining Generation 45334.64 74.98

Island Imbalance 15130.80 25.02

Shed Generation by Protection 401.10 0.66

Shed Load by UFLS Relays 12770.52 21.12

Table 6-6: SPP+AECI+WAPA Island Load Sheds by Area.


330 AECI 502.00 4089.26

515 SWPA 115.53 896.50

520 AEPW 1923.32 8465.59

523 GRDA 288.54 763.14

524 OKGE 1481.23 5122.22

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6-14


525 WFEC 347.58 1132.17

526 SPS 1486.79 4711.20

527 OMPA 89.23 283.16

531 MIDW 37.15 393.50

534 SUNC 233.92 1036.51

536 WERE 1440.14 4623.37

540 GMO 388.43 1636.33

541 KCPL 593.36 3054.20

542 KACY 177.77 376.26

544 EMDE 252.83 904.17

545 INDN 55.82 255.18

546 SPRM 187.37 585.72

640 NPPD 1134.91 2641.90

645 OPPD 892.52 1956.53

650 LES 232.61 521.89

652 WAPA 909.44 2732.99

SPP+AECI+WAPA 12770.49 46181.79

Table 6-7: Generators Tripped by Under-frequency Relays in SPP+AECI+WAPA Island.

Bus # Bus Name ID MW Generation @ Time (s)

641089 EGYCTR2G 18.0 2 248.00 1.27

546723 NM CT4 1 15.0 1 45.00 1.51

642067 PLATTE1G 13.8 1 108.10 1.74


Table 6-8: Frequency Summary of SPP+AECI+WAPA Island.

SPP+AECI+WAPA Frequency Hz @ Time (Sec)




6.3 Effect of the Under-Voltage Issue

In order to further demonstrate the insignificant effect of low voltages on under-frequency

situation, seven fictitious synchronous condensers were added at the 161 kV islanding buses of

zone 1616 of area 652 (WAPA), namely, 656087 (BREMER CO5 161.), 656201 (SHEFFLD5

161.), 656207 (HAMPTONTAP5 161.), 656283 (DRAGER5 161.), 656353 (HOPE5

161.), 656423 (BURT5 161.), and 656570 (WISDOM5 161.). These units were

represented by 100 MVA classical generator models having zero initial outputs, and therefore

did not change the load-generation imbalance and only provided basic dynamic voltage support.

The corresponding bus voltage magnitudes and bus frequencies of the island are plotted in Figure

6-3 and Figure 6-4, respectively. Comparing these figures to their counterparts before addition of

the seven synchronous condensers, the voltage support resolved the under-voltage situation

completely, while it slightly improved the bus frequency responses.

SPP 2014 UFLS Study


6-15

The corresponding load shedding results are summarized in Table 6-9 and Table 6-10.

Generators tripped by under-frequency relays are the same as before (see Table 6-7). These

results indicate slight improvements, and thus the original case represents a slightly more

pessimistic condition.

Table 6-9: SPP+AECI+WAPA Island Load Sheds by Area – 7 Fictitious Synchronous

Condensers Added in WAPA.


330 AECI 525.15 4066.11

515 SWPA 115.53 896.50

520 AEPW 2003.29 8385.63

523 GRDA 288.54 763.14

524 OKGE 1481.23 5122.22

525 WFEC 347.58 1132.17

526 SPS 1486.79 4711.20

527 OMPA 89.23 283.16

531 MIDW 37.15 393.50

534 SUNC 260.86 1009.57

536 WERE 1440.14 4623.37

540 GMO 485.38 1539.39

541 KCPL 593.36 3054.20

542 KACY 177.77 376.26

544 EMDE 252.83 904.17

545 INDN 55.82 255.18

546 SPRM 187.37 585.72

640 NPPD 1134.91 2641.90

645 OPPD 892.52 1956.53

650 LES 232.61 521.89

652 WAPA 895.32 2747.11

SPP+AECI+WAPA 12983.38 45968.92

Table 6-10: Frequency Summary of SPP+AECI+WAPA Island – 7 Fictitious Synchronous


SPP+AECI+WAPA Frequency Hz @ Time (Sec)




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6-16

Figure 6-1: Bus Voltage Magnitudes of SPP+AECI+WAPA Island – No Fictitious Synchronous

Condensers Added.

Figure 6-2: Bus Frequencies of SPP+AECI+WAPA Island – No Fictitious Synchronous

Condensers Added.

SPP 2014 UFLS Study


6-17

Figure 6-3: Bus Voltage Magnitudes of SPP+AECI+WAPA Island – 7 Fictitious Synchronous


Figure 6-4: Bus Frequencies of SPP+AECI+WAPA Island – 7 Fictitious Synchronous


SPP 2014 UFLS Study


6-18

6.4 Sensitivity of an Entity with Peak Load under 75 MW

Entities with their total peak load under 25 MW are not expected to participate in the SPP UFLS

plan (already removed from the relay list). It is being suggested that Entities, whose total peak

load is less than 75 MW, can disarm their UFLS relays and not participate in the plan, as well.

As a result, the UFLS relay of the load listed in Table 6-11 (the same as that for SPP+AECI

island as listed in Table 5-9) was removed to evaluate its effect. The results are summarized in

Table 6-12. The total load shed is only 17 MW less and no measureable effect on other results

was observed (i.e., insignificant effect). This points out that for any other entity whose total peak

load is less than 75 MW, with more or less similar amount of available load for shedding, such as

Missouri River energy Services (MRES) & North Western Energy (NWE), the effect is expected

to be insignificant.

Table 6-11: Disarmed Entity in SPP+AECI+WAPA Island for Sensitivity Study.

Entity Area Bus Total Load

(MW)

Available for

Shedding (MW)

Carthage Water & Light 525 (WFEC) 505490 (CARTHG 2 69.0) 69.0 21.0

Table 6-12: SPP+AECI+WAPA Island Load Sheds by Area – Sensitivity.


330 AECI 502.00 4089.26

515 SWPA 98.53 913.49

520 AEPW 1923.32 8465.59

523 GRDA 288.54 763.14

524 OKGE 1481.23 5122.22

525 WFEC 347.58 1132.17

526 SPS 1486.79 4711.20

527 OMPA 89.23 283.16

531 MIDW 37.15 393.50

534 SUNC 233.92 1036.51

536 WERE 1440.14 4623.37

540 GMO 388.43 1636.33

541 KCPL 593.36 3054.20

542 KACY 177.77 376.26

544 EMDE 252.83 904.17

545 INDN 55.82 255.18

546 SPRM 187.37 585.72

640 NPPD 1134.91 2641.90

645 OPPD 892.52 1956.53

650 LES 232.61 521.89

652 WAPA 909.44 2732.99

SPP+AECI+WAPA 12753.49 46198.78

SPP 2014 UFLS Study


6-19

6.5 Volts per Hertz Assessment

V/Hz ratio is calculated for all individual generating units of the island greater than 20 MVA or

those units at a generating facility greater than 75 MVA. The V/Hz ratio at high voltage bus of

each GSU transformer is also computed. The analysis is performed using bus voltage and

frequency results of the 100-second simulation.

The V/Hz violation results of the island are presented in Table 6-13. As can be seen, there is no

short-term violation, and only five long-term violations. The associated generators of these

violations are wind turbines represented by CIMTR3 model having no dynamic controls. The

violations are minor as the steady-state ratios are just above the threshold of 1.1, which may be

considered to be within the simulation tolerances.

Table 6-13: SPP+AECI+WAPA Island V/Hz Results.

Bus # Bus Name Area

#

Area

ID

V/Hz Duration

(s) Maximum Minimum Steady-State

Criteria 1 1.180 2.0

None

Criteria 2 1.100 45

659289 DAYCNTYWND W0.69 652 WAPA 1.140 0.879 1.106 93

659290 POMONA W0.69 652 WAPA 1.142 0.879 1.104 91

659321 DAYCNTYWND 934.5 652 WAPA 1.140 0.872 1.103 90

659326 POMONA 934.5 652 WAPA 1.143 0.872 1.102 79

659367 BALDWIN 934.5 652 WAPA 1.153 0.919 1.114 95

It should be noted that for the case with added fictitious voltage support the first four violations

disappeared and the fifth V/Hz steady-state value reduced to 1.109. In other words, the under-

voltage issue of the original case causes a slightly more pessimistic condition in this respect.

Furthermore, the sensitivity case showed no change in V/Hz situation.

SPP 2014 UFLS Study


7-1

7. Conclusions

In this study, the SPP UFLS program was assessed for two islanding situations, namely,

SPP+AECI and SPP+AECI+WAPA. The islands were formed by tripping relevant ties, as well

as disconnection of generating units to create around 25% load-generation imbalance as required

by NERC PRC-006-1 Standard. To produce the worst-case scenario, all involved elements were

disconnected at once. A power flow base case representing the summer peak loading condition

of year 2014 was used for the assessment.

SPP provided detailed UFLS relay information in spread sheet format, which was translated to

appropriate PSS/E and TSAT models by PLI. Generator under-frequency and over-frequency

relays information were also translated to suitable PSS/E models. There was no Automatic Load

Restoration (ALR) in the SPP footprint and WAPA control area. PLI used in-house

DSAToolsTM

software package for simulations.

Time-domain dynamic simulations verified that the frequency criteria of the NERC Standard

were met in both islands using the approach of the above-mentioned worst-case scenario; the

voltage magnitude behaviors in these islands were reasonable, as well. Some buses, however,

showed low voltage magnitudes, especially in area 652 (WAPA) of the second island. By adding

some fictitious voltage support at seven key buses it was further demonstrated that such under-

voltage issues did not have any significant effect on the under-frequency and load shedding

results (i.e., they are two different phenomena). It may then be concluded that the current UFLS

program is adequate to meet the frequency criteria. The final load sheds and frequency statistics

are summarized in Table 7-1 below. Note that in both islands simulated in this study, three

generator under-frequency relays operated, which tripped around 400 MW of generation (in

addition to the created 25% generation deficit for each island).

Table 7-1: Summary of UFLS Operations and Frequencies.

Island Name

Shed Load Frequency (Hz)

MW % of Total Load

and Losses Minimum Maximum Steady-State

SPP+AECI 12421 21.9 58.36 60.07 59.81

SPP+AECI+WAPA 12771 21.1 58.06 60.32 59.78

Sensitivity studies were performed for an Entity with peak load under 75 MW; disarming its

UFLS relay (i.e., not participating in the SPP UFLS plan) did not indicate any measureable effect

on the results. Moreover, three historical events were documented.

In both islands, V/Hz was calculated for all individual generating units greater than 20 MVA, or

units at a generating facility greater than 75 MVA, as well as their transformer high-side buses.

The analysis was performed using bus voltage and frequency results of the 100-second long

dynamic simulations. The results were checked against both short-term (>1.18 pu for 2 seconds

cumulatively) and long-term (>1.1 pu for 45 seconds cumulatively) criteria. The first island

showed no violation at all. The second island showed no short-term violation, but a few minor

long-term violations, which were considered to be within the simulation tolerances.

SPP 2014 UFLS Study


8-1

8. Appendix A – Delivered Supporting Files

SPP+AECI+WAPA_LDSHBL.xls Updated Standard Load Shedding Data

2013 UFLS Feeder Tripping.xlsx Updated Feeder Load Shedding Data

SPP+AECI+WAPA_FRQTPA.xls Updated Generator Under/Over Frequency Tripping Data

SPP+AECI+WAPA_UFLS.dyr LDSHBL and FRQTPA Standard PSS/E Models

SPP_LS_UDM.dat Load Shedding User-Defined Models (UDM) in TSAT

Documents

SPP 2014 -Frequency Load Shedding (UFLS) Study 2014 ufls study final...spinning reserve is not adequate, Under-Frequency Load Shedding (UFLS) relays are used for initiating automatic