1 Methodology for Volt / Var Optimization …smartgrid.epri.com/UseCases/Volt Var on a Substation...VVO Substation V1.7.doc 1 Methodology for Volt / Var Optimization on a Substation

VVO Substation V1.7.doc 1

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1 Description of Methodology for Volt / Var Optimization (VVO) on a Substation Basis

This use case discusses how the utility will implement VVO on a substation basis. This implementation requires the development of rules to narrow feeder voltage profile to operate within a specific voltage range. Once the voltage band has been sufficiently narrowed; a decision could then be made to implement Conservation Voltage Reduction (CVR) for the substation.

1.1 Narrative The Utility’s Pilot Project will expand upon its Distribution Automation Project to include automatic voltage control capability on specific substations on a pilot and test basis. At a limited number of substations, the project will implement the coordinated operation of transformer load tap changer (LTC) controls, line voltage regulator controls (where already needed for operating reasons) and line capacitor bank controls to narrow feeder voltage ranges, and control distribution system voltage to within specific tolerances. The project will evaluate the feasibility of implementing real-time operational control capabilities regarding maintenance of system operating voltage and response to customer voltage variances. The project will also facilitate the experimental evaluation of CVR as a potential demand and energy conservation measure. The first Use Case associated with this project will develop a “Methodology for VVO on a Substation Basis”, establishing the functional requirements for an automated controller to meet the objectives outlined in the preceding paragraph. This use case has two scenarios. Scenario 1 discusses the Methodology for Voltage Narrowing on a Substation Basis. Scenario 2 discusses the Methodology for Conservation Voltage Reduction (CVR).


Operations

Advanced Distribution Management System(Doesn’t exist yet, but will in the future)

DistributionAutomationController

(DAC)

SCADAVolt-VAR

OptimizationController

Substation

Feeder CircuitBreaker

ProtectiveRelay

Field

Mid-PointOr Tie

Recloser Controller

Line CapacitorController

Line RegulatorController

Line VoltageSensor

653

1

4

RTU

Load TapChanger (LTC)

Controller

2

87

9

Figure 1-1 Utility VVO Communications Diagram

1.2 Actor (Stakeholder) Roles Actor Name Actor Type

(person, device, system etc.)

Actor Description Interface Points

Volt/Var Optimization (VVO) Controller

Device Volt/Var Optimization Controller is a device controlled and managed by D-SCADA and it interacts with RTUs and Field Devices.

1) SCADA

9) DAC

Line Capacitor Controller

Device Responds to On/Off commands from the Controller and reports status information, power system measurements, and alarms back to the Controller.

4) SCADA

RTU Device Remote Terminal Unit. A microprocessor controlled device that interfaces field devices to SCADA

2) SCADA

7) LTC Controller

8) Feeder


Actor Name Actor Type (person, device, system etc.)


Circuit Breaker Protective Relay

Line Regulator Controller

Device Responds to set point commands from the Controller and reports status information, power system measurements, and alarms back to the Controller.

5) SCADA

Midpoint or Tie Recloser Controller

Device A “programmable” circuit breaker designed to clear transient faults by opening on overcurrent and attempting one or more times to close, each time delaying for progressively longer. The programmed delays are a balance between minimizing outages and providing adequate time for the fault path to reacquire adequate dialectic strength, thus the progressive nature.

3) SCADA

Load Tap Changer (LTC) Controller

Device Responds to set point commands from the Controller and reports status information (tap position), power system measurements, and alarms back to the Controller

7) RTU

Line Voltage Sensor

Device Device that measures loading of feeder line in specific T & D grid sectors of the utility

6) SCADA

Feeder Circuit Breaker Protection Relay (Readings)

Device Class of IED that responds to faults by tripping a breaker according to control logic, based on the monitoring of current and voltage values, and on communications with other Protective Relays.

8) RTU


Actor Name Actor Type (person, device, system etc.)


SCADA System Supervisory Control and Data Acquisition system

The SCADA System retrieves data from the power system equipment, devices, and systems, and is used by operators and authorized applications to issue commands to power system equipment, devices, and systems.

1) VVO Controller

9) DAC

3) Mid-Point or Tie Recloser Controller

4) Line Capacitor Controller

5) Line Regulator Controller

6) Line Voltage Sensor

2) RTU

DCO Operator

Person An entity which carries the responsibility of operating an electricity distribution system

1.3 Information Exchanged

Information Object Name Information Object Description Information Format

Poll of RTUs Poll of the RTUs DNP/IP DNP serial

Feeder Circuit Breaker Protective Relay Feeder Readings

MW 3-Phase MVAR 3-Phase Volts

Amps

Mid-Point or Tie Recloser Open/Close


Information Object Name Information Object Description Information Format

Controller Status Volts

Amps

Block Automatic Operation

Blocks automatic operation of a LTC Controller or Line Regulator Controller

2 Step by Step Analysis of Methodology for Voltage Narrowing on a Substation Basis

2.1.1 Preconditions and Assumptions Actor/System/Information/Contract Preconditions or Assumptions

Communications Communications are functioning normally

VVO Includes voltage narrowing and CVR

LTC Controllers, Line Regulator Controllers, Line Capacitor Controllers

Local control will be in place for the controllers when communications go down.

Line Regulator Controllers and LTC Controllers

Band center is 123 volts and the bandwidth is 3volts in non-CVR mode. (The bandwidth is 121.5 volts to 124.5 volts.)

VVO Control Algorithms VVO Control Algorithms are trustworthy

Field Devices Field Devices are working properly

Field Devices Voltage measurement accuracy of Field Devices meets the minimum accuracy for which the voltage bands will be controlled.

RTU RTUs are scanned every 6 -8 seconds

Analogs are delivered every 20 seconds

RTU is scanning the substation and feeder devices

SCADA SCADA is polling RTUs

Cap Banks Controller Verification of Capacitor Bank operation is determined by measuring MVAR change following a command to open or close a bank.


2.1.2 Steps – Methodology for Voltage Narrowing on a Substation Basis

Step # Triggering Event Description of Process/Activity

Information Producer

Information Receiver

Name of Info Exchanged Additional Notes

1.1 An operational decision is made to implement “Voltage Narrowing”

DCO initiates VVO Controller for voltage narrowing

DCO VVO Controller

Initiate Voltage Narrowing

1.2.1 SCADA polls RTU for Feeder Circuit Breaker Protective Relay Feeder Readings

SCADA RTU Feeder Circuit Breaker Protective Relay Feeder Readings

Periodic Poll of field devices or Could be an alarm that triggers a poll

1.2.2 RTU returns Feeder Circuit Breaker Protection Relay Feeder Readings to SCADA

RTU SCADA Feeder Circuit Breaker Protective Relay Feeder Readings

1.2.3 SCADA polls Mid-Point or Tie Recloser Controllers to establish circuit topology

SCADA Mid-Point or Tie Recloser Controllers

Mid-Point or Tie Recloser Controller Status

Periodic Poll of field devices or Could be an alarm that triggers a poll

1.2.4 SCADA returns Mid-Point or Tie Recloser Controller Status to establish circuit topology

RTU SCADA Mid-Point or Tie Recloser Controllers Status






1.3 SCADA Blocks LTC Controllers and Line Regulator Controllers from automatic operation

SCADA LTC Controllers

Line Regulator Controllers


LTC Controllers and Line Regulator Controllers are blocked to prevent unnecessary operation (buck/boost) while the Power Factor is being corrected

1.4 SCADA Blocks Automatic Operation Line Cap Bank Controllers to Remote Control

SCADA Line Cap Bank Controllers


2.1 Perform Feeder PF correction based on feeder vars. Start with feeder 3 phase total MVAR and Voltage measurements from Capacitor Bank Controllers

Correcting PF to as close to unity as possible with capacitor bank controllers based on lowest voltage on the feeder

2.1A.1 If start of feeder 3 phase total MVAR is lagging greater than 50% of KVAR rating of the cap bank with the lowest operating voltage among those that are currently off, then turn it on if it has been off for greater than 5 minutes (via VVO control).






2.1A.2 If Line Capacitor Controller change command was initiated, wait 30 seconds and verify feeder MVAR have changed to determine if a capacitor bank operation occurred

30 second wait allows time to detect MVAR change following change command

2.1A.3 Repeat step until all Line Capacitor Controllers are On or PF is met on the feeder

2.1A.4 Do not enable Automatic Operation of Capacitor Bank Controllers

2.1B.1 or If start of feeder 3 phase total MVAR is leading greater than 50% of KVAR rating of the cap bank with the highest operating voltage among those that are currently closed, then turn it Off. (via VVO control).

2.1B.2 If cap bank change command was initiated, wait 30 seconds and verify feeder MVAR have changed to determine if a cap bank operation occurred

Change Command Open/Close

30 second wait allows time to detect MVAR change following change command

2.1B.3 Repeat previous two steps until all Line Capacitor Controllers are Off or PF is met on the feeder






2.1B.4 Do not enable Automatic Operation of Capacitor Bank Controllers

2.2C.1 or If PF is OK, go to step 3.1

3.1 Perform LTC Controller Bus Voltage correction

3.1.1 Unblock LTC Controllers to allow Automatic Operation to drive substation bus voltage to setpoint

Line Drop Compensation (LDC) is disabled on the LTCs

3.2A.1 LTC Controller steps up if the voltage is low

3.2B.1 or LTC Controller steps down if the voltage is high

3.3 Wait 30 seconds to allow LTC Controller to operate

3.4 Leave LTC controller in Automatic Operation mode.

4.1 Perform Voltage regulation via Line Regulator Controllers for feeder voltage correction






4.1.1 Sequentially unblock Line Regulators Controllers from Automatic Operation, starting at the head of the feeder and let them automatically correct the voltage

4.2A.1 Line Regulator Controller steps up if the voltage is low

4.2B.1 or Line Regulator Controller steps down if the voltage is high

4. 3 Wait 30 seconds (at each Line Regulator Controller) to allow the Line Regulators Controllers to operate

Wait 30 seconds to allow Line Regulator controllers to perform step functions

4. 4 Leave Line Regulator Controllers in Automatic Operation mode.

5.1 Perform Line Regulator Controller operation based on local voltage requirements

5.1.1 Allow RTU/SCADA to update






5.1.2 If any of the scanned voltages on the secondary side are still low and If the effected regulator setpoint is between 121.5v and 123v, place effected Line Regulator Controller in Remote Operation

5.13 Raise the Line Regulator Controller 1 step

Each regulator step will raise the voltage .75v

5.1.4 Wait 30 seconds to allow the Line Regulator Controllers to operate

5.2.1 If any of the scanned voltages on the secondary side are still low and If the effected Line Regulator Controller is setpoint s between 121.5v and 123v, raise the Line Regulator Controller 1 step

5.2.2 Wait 30 seconds to allow the Line Regulator Controller to operate

5.3 Voltage conditions lower than desired range after previous adjustments lead to design work on the feeder.






5.4 Place Line Regulator Controller in Automatic

2.1.3 Post-conditions and Significant Results

Actor/Activity Post-conditions Description and Results

VVO Control VVO Control can implement voltage narrowing on a substation level.

3 Step by Step Analysis of Methodology for CVR on a Substation Basis

3.1.1 Preconditions and Assumptions Actor/System/Information/Contract Preconditions or Assumptions

Communications Communications are functioning normally

VVO Includes voltage narrowing and CVR

LTC Controllers, Line Regulator Controllers, Line Capacitor Controllers

Local control will be in place for the controllers when communications go down.

Line Regulator Controllers and LTC Controllers

Band center is 123 volts and the bandwidth is 3volts in non-CVR mode. (The bandwidth is 121.5 volts to 124.5 volts.)

VVO Control Algorithms VVO Control Algorithms are trustworthy

Field Devices Field Devices are working properly

Field Devices Voltage measurement accuracy of Field Devices meets the minimum accuracy for which the voltage bands will be controlled.

RTU RTUs are scanned every 6 -8 seconds

Analogs are delivered every 20 seconds

RTU is scanning the substation and feeder devices


Actor/System/Information/Contract Preconditions or Assumptions

SCADA SCADA is polling RTUs

Cap Banks Controller Verification of Capacitor Bank operation is determined by measuring MVAR change following a command to open or close a bank.

3.1.2 Steps – Methodology for CVR on a Substation Basis Step

# Triggering Event Description of

Process/Activity Information

Producer Information

Receiver Name of Info Exchanged

Additional Notes

6.0 An operational decision is made to implement “Conservation Voltage Reduction”

Upon completion of Scenario 1

6.1.1 Drop the setpoint by .5 volts Volt/Var Controller

Volt/Var Controller

Internal VVO Controller Function

6.1.2 Volt/Var Controller sends new setpoints to LTC Controllers and Line Regulator Controllers

Volt/Var Controller

LTC Controllers and Line Regulator Controllers

New Setpoints

6.1.3 Go through Scenario 1 (Voltage Narrowing) with new setpoints.

6.1.4 Wait for next readings to update

Normal SCADA Poll

6.1.5 Check for violations of minimum voltage criteria.

Possible Voltage Alarms from SCADA

6.1.6 If all voltage criteria are met move to 6.2.1


Step #

Triggering Event Description of Process/Activity



Name of Info Exchanged

Additional Notes


Volt/Var Controller



Volt/Var Controller


New Setpoints



Normal SCADA Poll



6.2.6 If all voltage criteria are met move to 6.3.1


Volt/Var Controller



Volt/Var Controller


New Setpoints



Normal SCADA Poll


Step #

Triggering Event Description of Process/Activity



Name of Info Exchanged

Additional Notes



6.3.6 If all voltage criteria are met move to 6.4

6.4 Repeat cycle as desired for CVR.

3.1.3 Post-conditions and Significant Results

Actor/Activity Post-conditions Description and Results

VVO Control VVO Control can implement CVR on a substation level.


4 Diagrams

Scenario 1 – Voltage Narrowing Sequence Diagram


Scenario 2 – Conservation Voltage Reduction Sequence Diagram

5 Auxiliary Issues

5.1 Parking Lot Items

No Description

1 What protocol are the controllers talking? DNP?

2 What data/protocol does SCADA send to the VVO Controller? DNP?

3 VVO Controller must talk the same protocol as the SCADA – controllers/. DNP?

4 How do I know what field devices are incorporated on the circuit? Does the VVO Controller have an accurate system model to load? Do I scan the feeders and look for an open recloser?

5 What is the accuracy of the measurements coming back from SCADA?

6 How long does the condition need to exist?


5.2 Revision History

No Date Author Description

1.0 1-14-2011 B.D. Green Original Use Case

1.1 1-18-2011 B.D. Green Incorporate team input

1.2 1-24-2011 B.D. Green Add EPRI team notes

1.3 2-7-2011 B.D. Green Add new communications diagram and team comments

1.4 2-14-2011 B.D. Green Add team comments

1.5 2-15-2011 B.D. Green Add Diagrams

1.6 4-4-2011 B.D. Green Prepare for use case repository

1.7 5-13-2011 B.D. Green Clarification in Notes

Documents

1 Methodology for Volt / Var Optimization …smartgrid.epri.com/UseCases/Volt Var on a Substation...VVO Substation V1.7.doc 1 Methodology for Volt / Var Optimization on a Substation