Model Specifications and Testing for the 2nd Generation ...Model Specifications and Testing for the...

Model Specifications and Testing for the 2nd

Generation Wind Turbine Generator Models

Pouyan [email protected]

WECC REMTF WorkshopWECC REMTF WorkshopSalt Lake City, UT

6/17/14

BACKGROUND

• 1st Generation Wind Turbine Generator (WTG) models

• Were developed ~ 2005 – 2009• Concerns raised in 2010 with respect to:

T 1 & 2 h i bl f

2© 2014 Electric Power Research Institute, Inc. All rights reserved.

– Type 1 & 2 showing unreasonable frequency response– Type 3 & 4 not matching multiple vendors

BACKGROUND1st Generation WTG model versus actual WTG response

Type 3 WTG (WTG is not GE)


BACKGROUND

• Issues that needed to be addressed:T 1 & 2 WTG d t h d t d t bi– Type 1 & 2 WTGs need to have updated turbine controller model (for units with active stall / pitch control)

– Type 3 WTG needs more flexibility to cater for differentType 3 WTG needs more flexibility to cater for different vendor equipment

– Type 4 WTG needs more flexibility to cater for different vendor equipment

• Work started in late 2010 and ended in 2013• New models were implemented by GE Siemens PTI and• New models were implemented by GE, Siemens PTI and

PowerWorld in late 2013 / early 2014


MODEL DEVELOPMENT PROCESS FOR 2nd GENERATION WTG MODELS


THE MODEL DEVELOPMENT PROCESS

• Started in 2010 under the Renewable Energy Modeling Task Force (REMTF) of WECCTask Force (REMTF) of WECC

• Worked in collaboration with the International Electrotechnical Commission (IEC) Working Group TC88 WG2 i d bi d liWG27 on wind turbine modeling

• The final models have many of the features of the IEC models; some aspects not adopted by WECC due tomodels; some aspects not adopted by WECC due to increased complexity

• EPRI lead much of the model development and testing working with several vendors under Nondisclosure Agreements (NDAs) to verify the models against actual measured field data from vendor equipment


q p

2nd GENERATION WTG MODELS2nd GENERATION WTG MODELS


MODEL SPECIFICATION DOCUMENTS

Summary of all specificationsSummary of all specifications

Detailed Type 1 & 2 specD t il d T 3


Detailed Type 3 specDetailed Type 4 spec

A MODULAR APPROACH WAS TAKENBuilding Blocks

RE System

Generator/converter

P/Q Converter

Control

WTG type 4= Block1 + Block2

+ etc….

Drive Train Plant Controller

WTG type 3= Block1 + Block2

+ etc

Pitch Torque C

+ etc….

Utility Scale PV control Control

A

yPlant

= Block1 + Block2 + etc….


Aero-dynamics

TYPE 1 & 2 WTG

• One of the major type 2 vendors has discontinued this product

• Most new installations in North America are either type 3 or type 4

• There are roughly 13 type 1 and 22 type 2 WTG plants existing in WECC (based on a 2014 base case)


WECC (based on a 2014 base case)

TYPE 1 & 2 WTG

• Type 1:• Generator model wt1g (not changed)• Generator model – wt1g (not changed)• Drive train model – wt1t (not changed)• Pitch controller – new model wt1p bPitch controller new model wt1p_b


TYPE 1 & 2 WTG

• Type 2:• Generator model wt2g (not changed)• Generator model – wt2g (not changed)• External resistor control – wt2e (not changed)• Drive train model – wt2t (not changed)Drive train model wt2t (not changed)• Pitch controller – new model wt1p_b


OLD PITCH CONTROL MODEL

• At minimum do not use the old pitch controller wt1p and wt2p – it does not correctly model the response of thosewt2p it does not correctly model the response of those units and can in some cases show inappropriate response during frequency events


New Pitch Controller

• The new model wt1p_b

Flag = 1 if Vt < vt4 & Po ≥ Pset, else = 0

not user defined, set by model automatically

during simulation


EXAMPLE PERFORMANCE


TYPE 3 WTG

New

Similar – some changes


GENERATOR / CONVERTER MODEL

Qgeno

Rate limits on reactive current for recovery after fault.Upward limit is active when Qgeno > 0Downward limit is active Qgeno < 0

Used by one vendor for one of their control strategies

when you have constant Q controlregc_a

-11 + s Tg

Vt

Iq

High Voltage Reactive Current

Iqcmd

Iqrmin

Iqrmax

s0

LVPL & rrpwr

Reactive Current Management

Iqrmin

wor

k M

odel

11 + s Tg

Ip

Low Voltage

Ipcmd

s1 Inte

rface

to N

etw

Low Voltage Active Current Management1

1 + s Tfltr

Lvpl1

Zerox Brkpt

LVPL

V

0

1

Lvplsw

s2


Zerox Brkpt

GENERATOR / CONVERTER MODELHVRC Management LVAC Management


CONVERTER P/Q CONTROL

reec_a


CONVERTER P/Q CONTROL


TURBINE-SHAFT MODEL

wtgt_a


AERO-DYNAMICS MODEL

wtgar_a

Based on: W. W. Price, J.J. Sanchez-Gasca, “Simplified Wind Turbine Generator Aerodynamic Models for Transient Stability

Studies” Proc. IEEE PES 2006 Power Systems Conference and Exposition (PSCE), Oct. 29-Nov. 1, 2006, Atlanta, GA, pp. 986-992.


PITCH CONTROLLER MODEL

wtgpt_a


TORQUE CONTROLLER MODEL

wtgtrq_a


PLANT CONTROLLER MODEL

repc_a


VALIDATION OF TYPE 3 MODEL

Just one example – ran many tens of cases of comparisons between measurement and simulation for those who provided data


TYPE 4A


TYPE 4B


VALIDATION OF TYPE 4A MODEL

Just one example – ran many tens of cases of comparisons between measurement and simulation for those who provided data


VALIDATION OF TYPE 4B MODEL

Just one example – ran many cases of comparisons between measurement and simulation for those who provided data


SUMMARY

Device regc_a reec_a wtgt_a wtgar_a wtgpt_a wtgtrq_a repc_aType 4 WTG A X X X XType 4 WTG B X X XType 3WTG X X X X X X XType 3 WTG X X X X X X X

Functionality Models Needed PfFlag Vflag Qflag RefFlagConstant pf control reec_a 1 N/A 0 N/AConstant Q control reec_a 0 N/A 0 N/ALocal V control only reec a 0 0 1 N/ALocal V control only reec_a 0 0 1 N/ALocal coordinated Q/V control only reec_a 0 1 1 N/APlant level Q control reec_a + repc_a 0 N/A 0 0Plant level Vcontrol reec_a + repc_a 0 N/A 0 1Plant level V Control + coordinated local Q/V control reec_a + repc_a 0 1 1 1Plant level Q Control + coordinated local Q/V control reec_a + repc_a 0 1 1 0


BENCHMARKING OF COMMERCIAL TOOLSExample plot showing consistency among three commercial tools

Type 4 WTG Infinite Bus

There are actuallyythree (3) plots here

but they match very closely!!!!

GE PSLFTM BlueGE PSLFTM – Blue Siemens PTI PSS®E – Red

PowerWorld – Green


CURRENT STATUS

• Models tested extensively for single wind turbine• Benchmarked across platforms• Benchmarked across platforms• Now available in all three major platforms in North America

• GE PSLFTMGE PSLF• Siemens PTI PSS®E• PowerWorld Simulator

• Testing done also on plant level controller to some extent -tl ki t ti th l t l l t llcurrently working on testing the plant level controller more

extensively


SOME THINGS TO WATCH OUT FORSOME THINGS TO WATCH OUT FOR


THINGS TO WATCH OUT FOR

• There are countless combinations and permutations of possible flag etc. – not all are valid.possible flag etc. not all are valid.

• There is no real default setting – please work with the vendors

• Do not worry too much about the spikes after a fault• Active crow bar is not modeled

E l t d i ti l i t d l d f t ti• Emulated inertial response is not modeled – future action• Active drive train damping is not explicitly modeled• Drive train is rough emulation does not represent physical• Drive-train is rough emulation – does not represent physical

system• The models are in general an emulation – do not


necessarily have one to one correspondence to actual control system

REPORTS

• All these explained in detail in the reports listed at the end of these slidesof these slides


THE SPIKES


TYPE 4 WTG – STATE CHANGEVendor 3

No re-setting of the state, which is ok

in planning simulations.


in planning simulations.This is as expected and previously explained

(see note 3., page 4-1 of type 4 report).

GENERATOR/CONVERTER MODEL


ACTIVE CROW-BAR


TORQUE CONTROLLER (a previous version)


STATOR CURRENT LIMIT

• The addition is to have an option for which we multiply Ipmax by the generator speed in the current limitIpmax by the generator speed in the current limit calculation, for Q-priority

• This can be done by adding one flag to the model


ACTIVE CROW-BAR MODEL (Type 3 – vendor 1)Original Proposed Model Adding Active Crow-Bar Representation and 1/Xe


ACTIVE DAMPING AND STATOR CURRENT LIMIT (Type 3 – vendor 2)LIMIT (Type 3 vendor 2)

Original Proposed ModelAdding Active Drive-Train Damping and

Stator Current Limit


LIGHT LOAD CONDITIONS

0.6• Generic models are too

0

0.2

0.4

eal P

ower

(pu)

MeasuredSimulated

• Generic models are too simple to attempt to fully capture the nuances of the oscillatory behavior

0 2 4 6 8 10 12-0.2

0Re

1

• Cannot necessarily use the same set of parameters for the simple model for all operating conditions

0

0.5

activ

e P

ower

(pu) Measured

Simulated•Torsional (local) oscillations do not have a significant impact on system voltage for cases where the short circuit

0 2 4 6 8 10 12-0.5

Re

Time (seconds)

cases where the short circuit levels are strong


FUTURE WORKFUTURE WORK


WHAT IS HAPPENING WITH ENERGY STORAGE?STORAGE?

• California: “Legislation (AB 2514) enacted in September 2010 allows for the adoption of requirements for utilities to2010 allows for the adoption of requirements for utilities to procure energy storage systems. ……The decision requires the utilities to collectively procure 1,325 MW of energy storage by 2020 which will be installed and delivering tostorage by 2020, which will be installed and delivering to the grid no later than the end of 2024.” http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=CA25R

Oth i Th h k ’ th i• Other regions: Through our work we’ve seen other regions also starting to adopt Energy Storage, e.g.

• ERCOT pilot for fast frequency responseERCOT pilot for fast frequency response• PV plants married with BES• Etc.


WHAT MODELS DO WE NEED?

• Compressed Air Energy Storage – GT model essentially• Pumped Hydro conventional generator / turbine models• Pumped Hydro – conventional generator / turbine models• BES – requires a FACTS type model• Fly Wheel - 5MWh unit in Stephentown, New York sinceFly Wheel 5MWh unit in Stephentown, New York since

2011; grid interface is inverter based• Essentially most ES technologies will use an power

t i t f t f ti l dconverter interface, except of course conventional pumped-hydro and CAES

• Note: Advanced pumped hydro also uses a converterNote: Advanced pumped hydro also uses a converter interface (IEEE TF on Adjustable Speed Pump Storage Modeling)


CONCEPT FOR GENERIC BES MODEL


HIGHER LEVEL PLANT CONTROLER

• A few projects where they have a plant controller communicating with turbines and a STATCOMcommunicating with turbines and a STATCOM

• The fact that it is possible to have multiple types of WTGs in a single WPP (or adjacent WPPs) that are coordinated via a single plant controller

• The fact that there are cases where other devices (e.g. shunt capacitor banks) are controlled by a central plant p ) y pcontroller


HERE IS THE CONCEPT TO BE DEVELOPED

The same concept could also be applied to the Real Power Control loop as well;

of course being only applicable to controlling multiple WTG or PV plants.


REFERENCES

WECC Approved Documents:• Type 1 & 2:

http://www.wecc.biz/committees/StandingCommittees/PCC/TSS/MVWG/Shared%20Documents/MVWG%20Approved%20Model%20Specifications/WECC%20Type%201%20and%202%20Generic%20Turbine%20Pseudo%20Governor%20model%20-%201012.pdf

• Type 3:http://www.wecc.biz/library/WECC%20Documents/Documents%20for%20Generators/WECC%20Type%203%20Wind%20Turbine%20Generator%20Model%20-%20Phase%20II%20012314.pdf

• Type 4:http://www.wecc.biz/library/WECC%20Documents/Documents%20for%20Generators/WECC%20Type%204%20Wind%20Turbine%20Generator%20Model%20-%20Phase%20II%20012313.pdf

• Summary of all specs:http://www wecc biz/library/WECC%20Documents/Documents%20for%20Generators/WECC%20Second%20Generatiohttp://www.wecc.biz/library/WECC%20Documents/Documents%20for%20Generators/WECC%20Second%20Generation%20Wind%20Turbine%20Models%20012314.pdf

Other Supporting Reports:• http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000003002001002 (This report includes the

test cases etc. for benchmarking the new models)

• http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000000001021753 (This report contains results for multiple simulations versus measurement data for various vendors)


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