Dynamic Reactive Power Control Dynamic Reactive Power Control for Wind Power Plantsfor Wind Power Plants

2009 www.sandc.com2009 www.sandc.com

for Wind Power Plantsfor Wind Power PlantsTechwindgrid 09 Grid Integration SeminarTechwindgrid 09 Grid Integration Seminar

Madrid 20/21 April 2009Madrid 20/21 April 2009

Ernst Camm Charles EdwardsErnst Camm Charles EdwardsKen Mattern Stephen WilliamsKen Mattern Stephen Williams

Presentation OutlinePresentation Outline

Introduction to S&C Electric CompanyIntroduction to S&C Electric Company

Introduction to Dynamic Reactive Power Control for Introduction to Dynamic Reactive Power Control for

Wind Power PlantsWind Power Plants

InverterInverter--based Dynamic Compensatorsbased Dynamic Compensators InverterInverter--based Dynamic Compensatorsbased Dynamic Compensators

Hybrid Reactive Power CompensatorsHybrid Reactive Power Compensators

Power Factor Control Using Hybrid Reactive Power Power Factor Control Using Hybrid Reactive Power

CompensatorsCompensators

Harmonic Resonance And Harmonic Current Injection Harmonic Resonance And Harmonic Current Injection

by WTGsby WTGs

SummarySummary

Introduction to S&C Electric CompanyIntroduction to S&C Electric Company

Established in 1911Established in 1911

EmployeeEmployee--owned companyowned company

Headquarters in Chicago, IL Headquarters in Chicago, IL

USAUSA

2,100 employees worldwide2,100 employees worldwide 2,100 employees worldwide2,100 employees worldwide

Leading provider of products Leading provider of products

and services for electric and services for electric

power switching, protection, power switching, protection,

automation, power quality automation, power quality

solutions, and engineering solutions, and engineering

servicesservices

Introduction to S&C Electric CompanyIntroduction to S&C Electric Company

Manufacturing & engineering Manufacturing & engineering

facilities in USAfacilities in USA Chicago, ILChicago, IL

Franklin, WIFranklin, WI

Orlando, FLOrlando, FL Orlando, FLOrlando, FL

Alameda, CAAlameda, CA

S&C subsidiariesS&C subsidiaries S&C Electric Canada LtdS&C Electric Canada Ltd

S&C Mexicana, S. de R.L. de C.V.S&C Mexicana, S. de R.L. de C.V.

S&C Electric do Brasil LtdaS&C Electric do Brasil Ltda

S&C Electric (Suzhou) Co., LtdS&C Electric (Suzhou) Co., Ltd

S&C Electric Europe LtdS&C Electric Europe Ltd

Introduction to Dynamic Reactive Power Introduction to Dynamic Reactive Power Control for Wind Power PlantsControl for Wind Power Plants

Grid code reactive power Grid code reactive power

requirements for wind power requirements for wind power

plantsplants

Vary power factor to meet Vary power factor to meet

system operating system operating

Bonus/Penalty by

demand period

[% of reference tariff]

Power Factor

Peak

(Punta)

Flat

(Llano)

Valley

(Valle)

InverterInverter--based Dynamic Compensatorsbased Dynamic Compensators

Voltage source inverter using PWM Voltage source inverter using PWM techniques to synthesize a voltage techniques to synthesize a voltage either greater than or less than the either greater than or less than the bus where the inverters are bus where the inverters are connected connected

Commercial inverterCommercial inverter--based dynamic based dynamic Commercial inverterCommercial inverter--based dynamic based dynamic compensators are available in compensators are available in modules of modules of 1.25 MVAR1.25 MVAR at 480 Vat 480 V

ShortShort--term capabilities of term capabilities of 3.3 MVAR3.3 MVARper module (i.e. per module (i.e. 264%264% of the of the continuous rating) for up to continuous rating) for up to 3 3 secondsseconds

Capability to swing from full inductive Capability to swing from full inductive to full capacitive output, or vice to full capacitive output, or vice versa, in about versa, in about 2 milliseconds2 milliseconds

InverterInverter--based Dynamic Compensatorsbased Dynamic Compensators

Two modules can be connected to Two modules can be connected to

a single 2.5 MVA, 0.48/33 kV stepa single 2.5 MVA, 0.48/33 kV step--

up transformer for connection to a up transformer for connection to a

33 kV (or other medium voltage) 33 kV (or other medium voltage)

collector substationcollector substation

Larger dynamic compensators are Larger dynamic compensators are Larger dynamic compensators are Larger dynamic compensators are

comprised of multiple comprised of multiple 2.5 MVAR 2.5 MVAR

units with stepunits with step--up transformersup transformers

A single A single 1.25 MVAR module can 1.25 MVAR module can

be connected via its own stepbe connected via its own step--up up

transformer if the total MVAR rating transformer if the total MVAR rating

requires an odd number of invertersrequires an odd number of inverters

Hybrid Reactive Power CompensatorsHybrid Reactive Power Compensators

Consist of an inverterConsist of an inverter--based based dynamic compensator and one or dynamic compensator and one or more mediummore medium--voltage mechanicallyvoltage mechanically--switched shunt capacitor banks and switched shunt capacitor banks and reactorsreactors

Dynamic compensator can control Dynamic compensator can control Dynamic compensator can control Dynamic compensator can control up to six switched shunt devices up to six switched shunt devices (SSDs)(SSDs) Can be configured to control Can be configured to control

either voltage, reactive power, or either voltage, reactive power, or power factorpower factor

Dynamic compensator is typically Dynamic compensator is typically sized such that the largest capacitor sized such that the largest capacitor or reactor bank does not exceed or reactor bank does not exceed about 70 to 75% of the rated total about 70 to 75% of the rated total dynamic rangedynamic range

Hybrid Reactive Power CompensatorsHybrid Reactive Power Compensators

Installation for 48 MW wind Installation for 48 MW wind

power plantpower plant

6.25 MVAR dynamic 6.25 MVAR dynamic

compensatorcompensator

two 8 MVAR, 33 kV shunt two 8 MVAR, 33 kV shunt two 8 MVAR, 33 kV shunt two 8 MVAR, 33 kV shunt

capacitor bankscapacitor banks

one 8 MVAR shunt reactorone 8 MVAR shunt reactor

Provides reactive power in the Provides reactive power in the

range of 0.95 leading range of 0.95 leading

(inductive) to 0.95 lagging (inductive) to 0.95 lagging

(capacitive) power factor at (capacitive) power factor at

the 33 kV POCthe 33 kV POC

Power Factor Control Using Hybrid Power Factor Control Using Hybrid Reactive Power CompensatorsReactive Power Compensators

Hybrid reactive power Hybrid reactive power compensators can be used to compensators can be used to dynamically control the power dynamically control the power factor at the POC with response factor at the POC with response times dictated by intentional delays times dictated by intentional delays associated with the switching of associated with the switching of

80

100

WPP MW

80

100

80

100

associated with the switching of associated with the switching of SSDsSSDs

Local collector bus voltage and Local collector bus voltage and current sensing and slow current sensing and slow feedback of voltage and current at feedback of voltage and current at the POC through SCADA allows the POC through SCADA allows compensator to dynamically control compensator to dynamically control the power factor at a remote POC the power factor at a remote POC using a line drop compensation using a line drop compensation algorithmalgorithm

-20

0

20

40

60

0 1 2 3 4 5 6 7 8 9 10 11M

W, M

VA

R

Hours

INVERTER MVAR WPP NET MVAR

-20

0

20

40

60

0 1 2 3 4 5 6 7 8 9 10 11M

W, M

VA

R

Hours

-20

0

20

40

60

0 1 2 3 4 5 6 7 8 9 10 11M

W, M

VA

R

Hours

Harmonic Resonance And Harmonic Harmonic Resonance And Harmonic Current Injection by WTGsCurrent Injection by WTGs

Application review must include review of potential Application review must include review of potential

harmonic resonance conditionsharmonic resonance conditions

Harmonic resonance analysisHarmonic resonance analysis

Harmonic distortion analysis based on representative Harmonic distortion analysis based on representative Harmonic distortion analysis based on representative Harmonic distortion analysis based on representative

ambient harmonic levelsambient harmonic levels

In cases where WTGs with power factor correction In cases where WTGs with power factor correction

capacitors are involved, careful attention must also be capacitors are involved, careful attention must also be

paid to any potential resonance conditions caused by paid to any potential resonance conditions caused by

the WTG capacitorsthe WTG capacitors

Harmonic Resonance And Harmonic Harmonic Resonance And Harmonic Current Injection by WTGsCurrent Injection by WTGs

If resonance conditions with high If resonance conditions with high local impedances at characteristic local impedances at characteristic harmonic frequencies (i.e. 5th, 7th, harmonic frequencies (i.e. 5th, 7th, 11th, 13th, etc. harmonics) are 11th, 13th, etc. harmonics) are identifiedidentified Capacitor banks in the hybrid Capacitor banks in the hybrid

reactive compensation system reactive compensation system reactive compensation system reactive compensation system can be converted to harmonic can be converted to harmonic filter banksfilter banks

If resonance conditions due to If resonance conditions due to WTGs with power factor correction WTGs with power factor correction capacitorscapacitors Damped CDamped C--type filter commonly type filter commonly

used to lower local impedance used to lower local impedance of the wind power plant over a of the wind power plant over a wide range of frequencieswide range of frequencies

0.01

0.1

1

10

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Harmonic number (n)

|Z|

Low OutputHigh OutputDamped

Harmonic Resonance And Harmonic Harmonic Resonance And Harmonic Current Injection by WTGsCurrent Injection by WTGs

If utilizing WTGs with DFIG or fullIf utilizing WTGs with DFIG or full--

converter WTGs with appreciable converter WTGs with appreciable

levels of harmonic current injectionlevels of harmonic current injection

Sometimes necessary to apply Sometimes necessary to apply

a higha high--pass filter to prevent pass filter to prevent

some of the harmonic currents some of the harmonic currents

Reactor

L

Resistor

Rsome of the harmonic currents some of the harmonic currents

from flowing into the system from flowing into the system

causing high levels of harmonic causing high levels of harmonic

voltage and current distortionvoltage and current distortion

If hybrid compensator is If hybrid compensator is

applied, one or more of the applied, one or more of the

capacitor banks can be capacitor banks can be

converted to highconverted to high--pass filterspass filters

Capacitor

C

R

SummarySummary

Hybrid reactive power compensation systems provide an Hybrid reactive power compensation systems provide an economical means of meeting typical grid code economical means of meeting typical grid code requirements for power factor and voltage controlrequirements for power factor and voltage control

The application and associated wind power plant and The application and associated wind power plant and power system parameters must be carefully reviewed topower system parameters must be carefully reviewed topower system parameters must be carefully reviewed topower system parameters must be carefully reviewed to Optimize the design of the hybrid reactive power Optimize the design of the hybrid reactive power compensatorcompensator

Identify any potential resonance conditions that may Identify any potential resonance conditions that may be caused by WTG power factor correction be caused by WTG power factor correction capacitors or collector substation capacitors applied capacitors or collector substation capacitors applied in the hybrid compensatorin the hybrid compensator