Expedited System Impact Assessment Report...unit with an ABB Unitrol-6000 full static excitation system due to equipment obsolescence. The replacement is scheduled to be done in September,

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Expedited System

Impact Assessment

Report

CONNECTION ASSESSMENT & APPROVAL PROCESS

CAA ID: 2012-EX594

Project: Mcphail G2 Excitation System Upgrade

Applicant: Brookfield Renewable Power

Market Facilitation Department

Independent Electricity System Operator

Date: August 31st 2012

Document Name Expedited System Impact Assessment Report

Issue Final

Effective Date August 31st 2012

Expedited System Impact Assessment Report Table of Contents

CAA ID 2012-EX594 3

Table of Contents

Table of Contents .....................................................................................................3

Executive Summary .................................................................................................4

Requirement for Conditional Approval for Connection. ................................................. 4

1. Project Description ...........................................................................................5

2. Data Verification ................................................................................................6

2.1 Generator ......................................................................................................... 6

2.2 Excitation System ............................................................................................. 7

2.3 Power System Stabilizer ................................................................................... 8

3. Assessments ................................................................................................... 10

3.1 Excitation System Performance ...................................................................... 10

3.2 Dynamic Study Results ................................................................................... 15

Expedited System Impact Assessment Report

CAA ID 2012-EX594 4

Executive Summary

The IESO recommends that a Notification of Conditional Approval for Connection be issued for the

replacement of the excitation system at Mcphail G2, subject to implementation of the requirements outlined in

this report. The proposed replacement of the excitation system at Mcphail G2 is expected to have no material

adverse impact on the reliability of the integrated power system.

Requirement for Conditional Approval for Connection. The connection applicant must complete the IESO Facility Registration/Market Entry process in a timely

manner before IESO final approval for connection is granted.

The applicant is required to ensure that the performance of the equipment that is eventually supplied and

installed at G2 of Mcphail GS is similar to or exceeds the performance of the existing system. As soon as the

commissioning tests are completed and actual data is available, the connection applicant is required to provide

an updated model of the excitation system and the PSS of Mcphail G2. Using these data the IESO will perform

studies to verify the behavior of the excitation system and establish the need for any new control and

adjustment, as part of the Facility Registration/Market Entry Process.

– End of section –


CAA ID 2012-EX594 5

1. Project Description

Brookfield Renewable Power-Wawa Hydro Operations plans to replace the excitation system for Mcphail G2

unit with an ABB Unitrol-6000 full static excitation system due to equipment obsolescence.

The replacement is scheduled to be done in September, 2012.

-End of Section-


CAA ID 2012-EX594 6

2. Data Verification

The applicant provided the dynamic models for generator, excitation system, and PSS as follows.

2.1 Generator Table 1: Generator Dynamic Data – Model GENSAE

CONs Value Description Units

J 1.97 T’d0 (sec) (>0) Sec

J+1 0.0587 T"d0 (sec) (>0) Sec

J+2 0.1105 T"q0 (sec) (>0) Sec

J+3 1.71 Inertia, H MW-s/MVA

J+4 0 D, Speed damping p.u

J+5 1.14 XD p.u

J+6 0.77 XQ p.u

J+7 0.497 X’D p.u

J+8 0.13 X"D = X"Q p.u

J+9 0.1 XL p.u

J+10 0.197 S (1.0) p.u

J+11 0.717 S (1.2) p.u


CAA ID 2012-EX594 7

2.2 Excitation System

Table 2: Excitation System Data – Model ESST1A

Figure 1: ESST1A Block Diagram

CONs Value Description

J 0.01 TR (sec)

J+1 99 VIMAX

J+2 -99 VIMIN

J+3 1 TC (sec)

J+4 3 TB (sec)

J+5 0.02 TC1 (sec)

J+6 0.02 TB1 (sec)

J+7 450 KA

J+8 0.0 TA (sec)

J+9 5.94 VAMAX

J+10 -5.23 VAMIN

J+11 5.94 VRMAX

J+12 -5.23 VRMIN

J+13 0.077 KC

J+14 0 KF

J+15 1.0 TF > 0 (sec)

J+16 20 KLR

J+17 3.42 ILR

Description ICONS Parameter Value

Alternate

UEL inputs IC UEL (1,2 or 3) 1

Alternate

Stabilizer

Inputs

IC + 1 VOS (1 or 2) 1


CAA ID 2012-EX594 8

2.3 Power System Stabilizer Table 3: PSS Data – Model PSS2A

Description CONS Parameter Value Units

First stabilizer input code IC ICS1 1 Rotor speed deviation (pu)

First remote bus number IC+1 REMBUS1 0 Sec

Second stabilizer input code IC+2 ICS2 3 Sec

Second remote bus number IC+3 REMBUS2 0 Sec

Ramp tracking filter order IC+4 M 5

Ramp tracking filter order IC+5 N 1

Washout time constant J Tw1 (>0) 10 Sec

Washout time constant J+1 Tw2 10 Sec

Filter time constant J+2 T6 0 Sec

Washout time constant J+3 Tw3 (>0) 10 Sec

Filter time constant [block bypassed] J+4 Tw4 0 Sec

Washout time constant J+5 T7 10 Sec

Gain J+6 KS2 2.92

Gain J+7 KS3 1 Sec

Ramp-tracking filter time constant J+8 T8 0.5 Sec

Ramp-tracking filter time constant J+9 T9 (>0) 0.1 Sec

Stabilizer gain J+10 KS1 10 Sec

Phase lead time constant J+11 T1 .03 Sec

Phase lag time constant J+12 T2 .01 Sec

Phase lead time constant J+13 T3 .03 Sec

Phase lag time constant J+14 T4 .01 Sec

Output limits J+15 VSTMAX .05 pu Etref

Output limits J+16 VSTMIN -0.05 pu Etref

Generator Apparent Power MBASE 6.927 MVA

Output limits H 1.71 MW-s/MVA


CAA ID 2012-EX594 9

Figure 2: PSS2A Block Diagram

-End of Section-


CAA ID 2012-EX594 10

3. Assessments

3.1 Excitation System Performance

Excitation system performance for Mcphail G2 was checked to verify the exciter’s positive and negative

ceilings, positive ceiling at rated terminal voltage and 160% of rated field current, and voltage response time.

Mcphail G2 rated field voltage (Efdrated) was determined from the proposed excitation system model provided by

the applicant. The unit ratings are shown in Table 4.

Table 4: Mcphail G2 Ratings

3.1.1 Field Voltage Ceiling Test

Appendix 4.2 in the Market Rules lists the requirements for exciters on generation facility directly connected to

the IESO-controlled grid to have positive and negative ceilings not less than 200% and 140% of rated field

voltage at rated terminal voltage and rated field current, and a positive ceiling not less than 170% of rated field

voltage at rated terminal voltage and 160% of rated field current.

3.1.1.1 Positive ceiling at rated field current

Simulations show that the proposed excitation system’s positive ceiling response meets the Market Rule

requirement.

The Response Ratio test in PSS/E was conducted to evaluate the positive ceiling voltage for the proposed

excitation system as well as the current one. The generator is first initialized to its rated MVA at rated power

factor. At t = 0, the voltage set point is raised suddenly in order to reach the exciter’s positive ceiling voltage as

quickly as possible. The response plot is shown in Figure 3.

It can be observed that the rated field voltage (Efd rated) is 2.05 pu and the positive ceiling voltage is 5.75 pu.

Therefore, the positive ceiling voltage exceeds 200% of the rated field voltage.

Description Value Units

Rated Voltage 1.0 pu

Rated Active Power 6.1 MW

Maximum Reactive Power 3 Mvar

Rated Field Voltage 2.05 pu

Rated Field Current 2.05 pu


CAA ID 2012-EX594 11

Figure 3: Positive Ceiling

3.1.1.2 Negative ceiling at rated field current

Simulations show that the proposed excitation system’s positive ceiling response meets the Market Rule

requirement.

A Response Ratio test was used to evaluate the negative ceiling voltage for the proposed excitation system. At

t=1, the voltage set point is dropped suddenly in order to reach the exciter’s negative ceiling voltage as quickly

as possible. The response plot is shown in Figure 4.

It can be observed that the rated field voltage (Efd rated) is 2.05 pu and the negative ceiling voltage is -5.23 pu.

Therefore, the negative ceiling voltage meets the Market Rule requirement of 140% of the rated field voltage.


CAA ID 2012-EX594 12

Figure 4: Negative Ceiling

3.1.1.3 Positive ceiling at 160% field current

Market rules requires that, at rated terminal voltage the excitation system should be able to reach the positive

ceiling of 170% of Efd rated when the field current is 160% of Ifd rated.

Test results depicted in Figure 5 shows that excitation system reaches Efd positive ceiling of 5.75 p.u (280% of

Efd rated), at the rated terminal voltage when field current is 160% of the Ifd rated and hence meets the requirement.


CAA ID 2012-EX594 13

Figure 5: Positive Ceiling at 160% Field Current

3.1.2 Field Voltage Response Time

Appendix 4.2 in the Market Rules lists the requirements for exciters on Generation facility directly connected to

the IESO-controlled grid to have a voltage response time to either ceiling not more than 50 ms for a 5% step

change from rated voltage under open-circuit conditions and a linear response between ceilings.

Based on the Market Rule requirement, for the +5% step response, the field voltage is required to reach 200% of

the rated field voltage within:

RTOC POS = 50* (1.95 Efd rated - Efd oc)/ (1.95 Efd rated - Efd rated) =

= 50* ((1.95*2.05) –1.16)/ ((1.95*2.05) – 2.05) = 72.85 ms

and for the -5% step response, the field voltage is required to reach -140% of the rated field voltage within:

RTOC NEG = 50* (1.28 Efd rated + Efd oc)/ (1.28 Efd rated + Efd rated) = 40.48 ms

Open circuit tests using PSS/E were conducted to evaluate the voltage response time for the proposed excitation

system. The generator is initialized to rated terminal voltage on an open circuit. At t = 0, the voltage set point is

increased or reduced by 5% to evaluate the excitation system’s voltage response time. The response plots

associated with the open circuit test are shown in Figure 6 and Figure 7. The initial open circuit voltage (Efd oc) is

1.16 pu.

Figure 6 shows that the proposed excitation system reaches an Efd of 5.81 pu, within 8.2 ms.


CAA ID 2012-EX594 14

Figure 6: Positive Ceiling Voltage Response Time

Figure 7 shows that the proposed excitation system reaches an Efd of -5.1 pu, which is greater than -140% of the

rated field voltage, within 3.2 ms.

Figure 7: Negative Ceiling Voltage Response Time


CAA ID 2012-EX594 15

3.2 Dynamic Study Results

Transient stability analysis was carried out to investigate the impact of the replacement of the excitation system

of G2 at Mcphail GS on the reliability of the IESO-Controlled grid.

The 2014 summer basecase was used as a starting point for the analysis. The transient stability analysis was

performed with all transmission elements in service. A LLG fault on the 115 kV circuit High Falls #1 at

Anjigami TS with normal clearing time was applied. Upon clearing of this fault, circuit High Falls #1 would be

tripped and all the generators connected to Da Waston TS would remain connected to the system.

The rotor angle of generator G2 at Mcphail GS was monitored for two cases: 1) with the PSS operating, and 2)

without the PSS operating. The results displayed in Figure 8 show that the presence of the PSS helps damping

the oscillations in the rotor angle of the machine. Moreover, the results displayed in Figure 9 show that the

generators in the vicinity of Mcphail GS have a stable performance and the oscillations are well damped.

Therefore, based on the transient stability study results it can be concluded that the proposed replacement of the

exciter of G2 at Mcphail GS would not adversely impact the reliable operation of the IESO-controlled grid.

Figure 8: Rotor Angle of G2 at Mcphail GS with and without the PSS


CAA ID 2012-EX594 16

Figure 9: Rotor Angles of Surrounding Units

-End of Report-

Documents

Expedited System Impact Assessment Report...unit with an ABB Unitrol-6000 full static excitation system due to equipment obsolescence. The replacement is scheduled to be done in September,