Integrated Volt/VAR Control

Mike Prevallet, Sales Engineer

Tom Johnson, Regional Director-Energy Automation Solutions

EAS – Smart Grid Solution Leader

CPS Controls

Building one team focused on software, controls, and communications with

250+ engineers focused on intelligent grid solutions

3

Agenda

How does Volt-Var Management benefit utilities?

What is Volt-Var Management?

Power Factor and Voltage Optimization Requirements

Volt-Var input values from capacitor controls, voltage regulator controls and LTC; algorithm decisions

Questions

Volt/Var Fundamentals

Switching capacitors on will reduce the electric

current (I) on the line, which will:

Reduces the electrical losses (I2R)

Reduces the amount of energy (kilowatt-hours) required to

supply the existing load and reduces the peak demand on the

system

Indirect control of feeder voltage through Capacitor

Switching which raises the feeder voltage to:

Increases the real and reactive load (depending on the kind of

device)

However, this increases losses in distribution transformers

4

5

Change in voltage leads to a corresponding

change in power consumption:

a 1% change in voltage causes a change in kW

usually ranging from 0.2% to 1.5%

Effect of change of voltage on reactive power is

even more significant :

1% change in voltage causes a change in kvar

usually ranging from 2% to 6%

Volt/Var Fundamentals

The change in load will decay over time, but not to the value before the

change in voltage. The amount and time constant of decay depend on the

characteristics of the circuit. **KEMA PES Conference June 2005/IEEE Transactions on Power Systems, Vol. 10, No. 2, May 1995; pp. 709-715

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VAR Optimization - Power Factor CorrectionDistribution feeder capacitor bank control provide energy loss

reduction by coordinating capacitor banks control.

Conservation Voltage Reduction (CVR)Coordinating voltage regulator and LTC controls to reduce feeder

voltage levels provide load reduction on substations and feeders.

Integrated Volt/VAR Control (IVVC)Coordinated Control of substation load tap changers, feeder

voltage regulators and capacitor banks ensure VAR and voltage

profiles to optimize these benefits.

Why Now?Utility Investment in communications and Smart Grid investment

links all facets from End-Customer to Generation, Transmission

and Distribution

Volt-Var Optimization Strategies

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How does IVVC benefit Utilities?

88

Integrated Volt/VAR Management

Business DriversRegulation imposes new requirements with the overall goal

of reducing energy consumption and demand - (Reduction

in peak load MW) x ($/MW to add capacity or demand

charges)

Stimulus bill driven energy efficiency projects such as

Decoupling Rates/Green initiatives - Capacity release

(MW) due to reduced losses (typically a very sizable $

benefit)

Business Case

Energy purchase savings – Reduction in Energy (MWh) to

serve losses (can be a very sizable $ benefit)

Conservation Voltage Reduction - (Reduction in Losses

MWh) x ($/MWh to generate or purchase energy)

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Business Drivers

Pennsylvania PUC Act 129 Information: Seven major Electric Distribution Companies (EDCs) in

Pennsylvania need to implement a plan to reduce energy demand and consumption.

The Act requires a 1% reduction in consumption by May 31, 2011, a total of 3% reduction in consumption and a 4.5% reduction in peak demand by May 31, 2013.

Ohio PUC Senate Bill 221 Information: Commission proposed electric distribution utilities will

implement a cost-effective energy efficiency and peak demand reduction –

Bill 221 benchmarks nominal requirements for more cost effective decisions to provide energy conservation than to provide power, electric distribution utilities must offer energy savings to lower generation purchases.

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Business Drivers

Snohomish CVR 2006: Robert Fletcher of Snohomish PUD said conservation

voltage reduction drops the utility's voltage by 2.5 percent, to 117V.

"That buys the average customer about 350-400 kWh per year savings," Fletcher said. "So the net savings for our customers is about $3.5 million a year.“

Northwest Energy Efficiency Alliance Distribution Efficiency Initiative: 13 Northwest utilities consolidating research efforts validate

value of conservation voltage reduction

Results from “The NEEA Phase 1 DEI Final Report” shows that "operating a utility distribution system in the lower half of the acceptable voltage range (120-114 volts) saves energy, reduces demand, and reduces reactive power requirements without negatively impacting the customer.

Validated energy savings results of 1 to 3 percent total energy reduction, 2 to 4 percent reduction in kW demand, and a 4 to 10 percent reduction in kvar demand.”

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What is Integrated Volt-Var Management?

System Approach to Savings

Local Control:

Power Factor

Load Current

Voltage

Var-Flow

Temperature

Time of Day /

Season

Centralized Automation:

System Overview of

Assets

Conditioned Based

Optimization for -

Voltage

Var – power factor

Maintenance

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Integrating the LTC’s and Regs provides Real-time Voltage & PF data to

operate the correct capacitor or regulator and optimize system efficiency

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What is Integrated Volt/VAR

A Flat Feeder Voltage Profile. (improved voltage profile)

Unity Power Factor (minimize losses)

The ability change the voltage on demand

– Demand Response - conservation voltage reduction

The ability to define roles where Voltage or Power Factor are the primary metric based on advance algorithms, real-time data, power flow, constraints and system dynamic needs.

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Case 1: No Voltage Regulation

Voltage drops off with distance from the substation

– On-load Tap Changer on substation transformer, or substation regulators step up voltage so that voltage at end of feeder stays within required range

VAR injected at substation (for inductive loads)

– Either via generator or substation capacitor bank

Can be very difficult to manage Volt/VAR within target range on a long feeder with numerous loads of varying types

Severe penalties for not maintaining power factor

Substation LTC or

Voltage Regulators

1ph

XFMR

End

Customer

Line Voltage

Regulator

Cap

Bank

Distribution ConsumptionGeneration & Transmission

Vo

ltag

e

Distance from Substation

Target

1515

Case 2: Distributed Voltage Regulation

Optimized planning for placement of Regulators – Cyme

Standalone Voltage Regulators added along the way keeps Voltage in a tighter range

Benefits– Minimize/avoid voltage violations

– Improve efficiency by reducing “average voltage”

Substation LTC or

Voltage Regulators

1ph

XFMR

End

Customer

Line Voltage

Regulator

Line Voltage

Regulator

Distribution ConsumptionGeneration & Transmission

Vo

ltag

e

Distance from Substation

Target

1616

Case 3: Traditional Volt/VAR Management

Optimized planning for placement of Regulators and Capacitor Banks – Cyme

Adding capacitor banks to the system further flattens the voltage profile

Benefits

– Minimize/avoid voltage violations

– Improve efficiency by reducing “average voltage”

– Improves power factor

– Frees up generating capacity by injecting VARs; reduced generation

Substation LTC or

Voltage Regulators

1ph

XFMR

End

Customer

Line Voltage

Regulator

Cap

Bank

Line Voltage

Regulator

Distribution ConsumptionGeneration & Transmission

Vo

ltag

e

Distance from Substation

Target

1717

Case 4: Integrated Volt/VAR

Optimized planning for placement of Regulators and Capacitor Banks – Cyme

With Integrated Volt/Var (IVVC), regulators, load tap changes and capacitors are continuously monitored & controlled to manage power factor and voltage

Additional Benefits

– Volt/VAR is optimized in real time for power quality and system efficiency

– Utilities can perform Conservation Voltage Reduction to shed load - 1% reduction in voltage = 0.5-0.7% reduction in load

Substation LTC or

Voltage Regulators

1ph

XFMR

End

Customer

Line Voltage

RegulatorsCap

Bank

Line Voltage

Regulators

Distribution ConsumptionGeneration & Transmission

Vo

ltag

e

Distance from Substation

Target

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Power Factor and Voltage

Optimization Requirements

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Functional Requirements

Control Set Points System evaluates optimization pattern to control LTC and regulator

set points and tap positions

System optimizes capacitor bank statuses to flatten voltage in the distribution to the specified target.

Targeted Power Factor The Volt-VAR Management application evaluates how to change

capacitor bank statuses to manage feeder and substation VAR flows as close to a specified target power factor.

Loss of Communications Failover / Recovery support System communications support a failover and recovery scheme to

insure voltage quality is maintained when communications from the application to the controls fails.

Communications Band-Width Management Measurement Communications by exception to reduce the message

traffic in the communications network.

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Functional Requirements

Feeder Reconfiguration Integration switch status change and data processing

Results in dynamic coordination of feeder capacitor banks, feeder measurement points, and substation LTCs, and regulators.

Voltage targets Support for normal and emergency voltage targets to allow

for emergency CVR operation

Control Center Operations Support disabling/enabling Volt/VAR Management automatic

control from the control center/operations desk.

System Integration SCADA/DMS/OMS integration to support capacitor bank,

LTC, and regulator supervisory control actions from the control center operations desk.

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Volt-Var System Input Values

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Field Hardware

Communication Enabled – Hardware

for voltage, Var, and substation current/watts (bias)

Substation Regulators

Substation Capacitor Banks Controls

Down-line (Feeder) Regulators

Feeder Capacitor Bank Controls

Medium Voltage Sensors

Customer Meters

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Volt/Var Management Algorithm

IVVC Algorithm is triggered by:

Value limit violation

Periodic interval

IVVC Algorithm Sequence of Events:

Scan and Correlate Measurement Data Set

Evaluate Feeder Voltage Profile and Power Factor

Evaluate if Device control actions could improve:

Feeder Voltage Profile

Substation and Feeder Power Factor

Calculate costs for current operating state, proposed operating

states.

Optimization resolves conflicts between Voltage and Power

Factor targets and minimizes the number of control actions.

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IVVC Optimization Table

Algorithm Resolves Constraints

Cost for voltage and Var used to determine

operation. Capacitor vs Regulator/LTC

Decision criteria to resolves voltage or VAR

violation

The utility defines/selects resolution costs and

metrics through solution weighting

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Volt/Var Management Implementation

Data Requirements: Data is provided in a formatted flat

file and imported to the Volt/Var Management application

via a standard data import script

Static Device Attributes examples are Capacitor Bank size, LTC and

Regulator static attributes: Primary and Secondary voltages, Number of

taps, max/min voltages, bandwidth

Regulation Settings examples are Cap Bank Regulation type (Volt,

Var, Time, Temp), regulation target, regulated phase are integrated in the

model

Nominal feeder topology: examples include Cap Bank/Regulator to

feeder section, Cap Bank/Regulator to Sectionalizing Switches (SCADA

Switch, Sectionalizers, Reclosers), Cap Bank/Regulator to feeder, Cap

Bank/Regulator to substation bus, Device to control zone

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Volt/Var Management Requirements

Integration Requirements:

Real Time Measurement Data: Volts, Amps, Watts and

Vars at each control device and each meter location

Typically Utilities integrate with: SCADA , OMS, DMS

EMS and database systems to support operational objectives for

application status and control positions

Sectionalizing Switch Positions: Support automated

recoordination of feeder cap banks and regulators to the

appropriate feeder and substation bus after feeder switching

Example Architecture- IVVC

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PI Database

AMI

Meter

YUKON

IVVC

SERVER

Regulator/LTC

Cap Controller

Recloser

Field

Commands

Fie

ld

Co

mm

and

s

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Summary

Business Drivers Business Objectives

Functional Objectives Technical Requirements

Monitor and control substation regulators

or LTCs (Regulator Controls)

Monitor and control substation and feeder

capacitor banks (Cap Bank Controls)

Monitor end of line voltages to avoid

violations (Smart Meters, Sensors, etc.)

Manage Feeder Voltage down to a settable

target

Manage Feeder VARs to a settable target

Flat voltage profile

Regulation imposes new requirements

with the overall goal of reducing energy

consumption and demand

Energy purchase savings

Increased KWh sales on improved voltage

profile

Stimulus bill driven energy efficiency

projects

Unity Power Factor minimizes losses and

minimizes purchased KW

Reduced voltage profile minimizes

purchased KW:

1% reduction in voltage results in 0.5

to 0.8% reduction in KW

IVVC Solutions Improve Grid Efficiency