Modeling and Model Validation of Wind Turbine Generators – US and International Efforts

Pouyan Pourbeikppourbeik@epri.comEnernex WorkshopAugust 17, 2011

2© 2011 Electric Power Research Institute, Inc. All rights reserved.

MODELING AND MODEL VALIDATION

Why do we develop power system models?

– Planning/Operations require extensive modeling and analysis– There should be no misconception that computer models

provide all the answers – However, better models = reduced uncertainties → more

educated and economic decisions

Model Validation ↔ System Reliability

3© 2011 Electric Power Research Institute, Inc. All rights reserved.

POWER SYSTEM STABILITY

Reproduced from [7]

• Voltage Stability

• Rotor Angle Stability

• Small-Signal Stability

• Frequency Control and Stability

4© 2011 Electric Power Research Institute, Inc. All rights reserved.

WIND GENERATION TECHNOLOGIES [1], [2]

generator

full power

PlantFeeders

actodc

dctoac

generator

partial power

PlantFeeders

actodc

dctoac

generator

Slip poweras heat loss

PlantFeeders

PF controlcapacitors

actodc

generator

PlantFeeders

PF controlcapacitors

Type 1 Type 2

Type 3 Type 4

Type 3 & 4 are predominantly what is being deployed these days; however,there is a significant installed based of type 1 & 2 in North America and Europe

5© 2011 Electric Power Research Institute, Inc. All rights reserved.

VARIOUS INDUSTRY EFFORTS ON MODEL DEVELOPMENT, VALIDATION AND DOCUMENTATION

• NERC Integration of Variable Generation Task Force

• WECC Renewable Energy Modeling Task Force (REMTF)– Chair: A. Ellis, SNL

• IEC TC88 WG27– Chair: P. Sørensen, Risø

• IEEE Dynamic Performance of Wind Generation WG– Chair: P. Pourbeik, EPRI

6© 2011 Electric Power Research Institute, Inc. All rights reserved.

NERC IVGTF Task 1-1: Standard Models for Variable Generation Scope

• Standard, valid, generic, non-confidential, and public power flow and stability models (variable generation) are needed and must be developed, enabling planners to maintain bulk power system reliability.

• Make recommendations and identify changes needed to NERC’s MOD Standards.

7© 2011 Electric Power Research Institute, Inc. All rights reserved.

• Introduction• The Need for Models for Variable

Generation • Present Status of Modeling Variable

Generation• Present Status of Model Validation• Summary & Recommended Actions –

Standards Implications

• Report issued in May 2010 andapproved by NERC in June 2010 [7]

• Recommendations discussed and communicated to NERC SDTs

REPORT CONTENT [7]

Special ReportStandard Models for Variable Generation

8© 2011 Electric Power Research Institute, Inc. All rights reserved.

HIGHLIGHTS OF NERC TF RECOMENDATIONS

• MOD-011: Regional Steady-State Data Requirements and Reporting Procedures– Need to specify more clearly applicability to VG

• MOD-012: Dynamics Data for Transmission System Modeling and Simulation– MOD already general enough to cover VG

• MOD-013-1: RRO Dynamics Data Requirements and Reporting Procedures– Beneficial to include an explicit statement to cover variable generation

• MOD-024-2 — Verification and Data Reporting of Generator Real Power Capability– As of 2010 this MOD indicated VG was exempt– For a VG plant the definition of Real Power Capability can be slightly

challenging• MOD-025-1 — Verification of Generator Gross and Net Reactive Power

Capability– For a VG plant the definition of Real Power Capability can be slightly

challenging– Examples and concerns illustrated in the report

9© 2011 Electric Power Research Institute, Inc. All rights reserved.

HIGHLIGHTS OF NERC TF RECOMENDATIONS

• MOD 26 - Verification of Models and Data for Generator Excitation System Functions (and MOD 27)

– Unit/Plant Size for Validation– Validation of various technologies in a single plant

• Uniform VG plant (i.e. all units same technology) a single aggregate generator model

• Diverse VG plant, the plant should be represented by multiple aggregated unit models

– Validation of different control layers– Modeling and Model Validation:

• Models should state clearly the type and the range of events they have been designed to simulated, and the limitation of the model should be defined.

• Best approach to model validation is to use field (or test bench) measurements of various disturbances that exercise the different control functions

• A model is valid if its dynamic behavior is close enough to reality – perfect curve fitting is not necessary

– Future functionality – Modeling of protection – Issues related to the fuel source for variable generation – Revalidation

10© 2011 Electric Power Research Institute, Inc. All rights reserved.

WECC REMTF

• Developed the first generation of generic WTG models (in commercial software tools)– Type 1: WT1G, WT1P, WT1E, WT1E– Type 2: WT1G, WT1P, WT1E, WT1E– Type 3: WT1G, WT1P, WT1E, WT1E– Type 4: WT1G, WT1E, WT1E

• Working towards generation two of the models– Several proposed changes have been put forth [3], [4], [5]– EPRI has been engaged in making some of these proposals and

testing then [4]

• Group membership: utilities, R&D, consultants and vendors (GE, Siemens, Nordex, Vestas, etc.)

11© 2011 Electric Power Research Institute, Inc. All rights reserved.

IEC TC88 WG27 SCOPE

• The purpose to define standard dynamic simulation models for wind turbines and wind power plants

• IEC 61400-27-1 (PART 1) generic wind turbine models

• IEC 61400-27-2 (PART 2) generic wind power plant models

• Both standards to include procedures for validation

• The electrical simulation models being specified are to be independent of any software simulation tool

12© 2011 Electric Power Research Institute, Inc. All rights reserved.

IEC GROUP MEMBERS

• 39 members (15 Countries)

• Utilities, Vendors, R&D, Universities, Transmission Owners

• Had seven meetings so far and moving forward

• Two subtask:– Model structure– Model validation

• Starting with WECC models

• Working in many ways in parallel with WECC REMTF

13© 2011 Electric Power Research Institute, Inc. All rights reserved.

IEEE WORKING GROUP

• IEEE Dynamic Performance of Wind Power Working Group

• Held two tutorials on modeling 2008 & 2009 (at IEEE Conferences)

• Two publications in 2011– Working Group Joint Report – WECC WGDP & IEEE DPWP Generation,

“Description and Technical Specifications for Generic WTG Models – A Status Report”, Proceedings of IEEE PSCE, March 2011 [2]

– IEEE ad hoc TF on Wind Turbine Model Validation, “Model Validation for Wind Turbine Generator Models”, To be published in IEEE Transactions on Power Systems [6]

• Held Panel Session on Modeling and Model Validation at IEEE PES GM, July 27th, 2011– Very well attended– Presentations by EPRI, Siemens PTI, GE, REPower, AEMO, Hydro

Quebec, and IEC

14© 2011 Electric Power Research Institute, Inc. All rights reserved.

OTHER INDUSTRY EFFORTS

• UWIG/Enernex– Has held several Workshops in WECC, NYISO and a

few more to come– Working on documentation and archiving of model and

model validation work

• EPRI P173.003 Project– Working closely with WECC REMTF, IEC TC88 WG27,

IEEE, etc.– Working on model structure changes for WT3 & 4 [4]– Working on model validation based on measured data– Hold workshops (e.g. in September 2010; Charlotte,

NC)

EXAMPLE OF THE TECHNICAL WORK

16© 2011 Electric Power Research Institute, Inc. All rights reserved.

WECC GENERATION 1 WT4 MODEL [1]

17© 2011 Electric Power Research Institute, Inc. All rights reserved.

PROPOSED MODIFICATIONS – Q CONTORL [2]

18© 2011 Electric Power Research Institute, Inc. All rights reserved.

PROPOSED MODIFICATIONS – P CONTORL [2]

New

New

From

WT3

19© 2011 Electric Power Research Institute, Inc. All rights reserved.

OVERALL STRUCTURE

ElectricalControls

Ipcmd

Iqcmd

Pe

PrefVref or

Qref or

pfref Vt

g

Qe

errPord

Generator/Converter

φ∠Isoc

Pe Qe

Aerodynamics/Drive Train

Pe

g

Pref

Pmo

o

o

20© 2011 Electric Power Research Institute, Inc. All rights reserved.

SIMULATION SIMPLY TO ILLUSTRATE VARIOUS MODEL STRUCTURE OPTIONS

0 2 4 6 8 100

0.2

0.4

0.6

0.8

1

1.2

Time (seconds)

Pe

(pu)

Pflag=0Pflag=1

- Just a simulation

- Does not represent any equipment

- Simply illustrating the various modes of the model

21© 2011 Electric Power Research Institute, Inc. All rights reserved.

MODEL VALIDATION

0 20 40 60 80 100 1201.9

2

2.1

Time (seconds)

Vfd

(pu

)

0 20 40 60 80 100 1200.95

0.96

Vt

(pu)

0 20 40 60 80 100 1201.95

2

Ifd

(pu

)

Measured

Fitted

PMU/DFR

at Plant

Grid Disturbance

Proven EPRI Technology for Conventional Plants – PPPD Tool

PMU at POI

Grid Disturbance

Ultimate Vision for RE

22© 2011 Electric Power Research Institute, Inc. All rights reserved.

SUMMARY & WORK IN PROGRESS

• Continue collaboration among the various groups WECC REMTF, IEC TC88 WG27, NREL, SNL, Enernex, EPRI etc. to get 2nd generation generic WTG models out

• Model validation work– Actively seeking all avenues of data for further

validation testing of the generic models – this continues to be a challenge

23© 2011 Electric Power Research Institute, Inc. All rights reserved.

REFERENCES

[1] CIGRE Technical Brochure 328, Modeling and Dynamic Behavior of Wind Generation as it Relates to Power System Control and Dynamic Performance, Prepared by CIGRE WG C4.601, August 2007. www.e-cigre.org

[2] A. Ellis, Y. Kazachkov, E. Muljadi, P. Pourbeik and J. J. Sanchez-Gasca, “Description and Technical Specifications for Generic WTG Models – A Status Report”, Proceedings of the IEEE PSCE, March 2011.

[3] Y. Kazachkov and P. Pourbeik, “Review of discussions on structure and functionality of wind generic model”, Memorandum to IEC TC88 WG27, May 6, 2011.

[4] P. Pourbeik, “Proposed Changes to the Type 4 Generic Wind Turbine Generator Model (WT4)”, Memorandum to IEC, WECC and P173, May 12, 2011.

[5] J. Fortmann, S. Engelhardt, J. Kretschmann, C. Feltes, M. Janssen, T. Neumann and I. Erlich, “Generic Simulation Model for DFIG and Full Size Converter based Wind Turbines”, Workshop on Large-Scale Integration of Wind Power into Power Systems, Quebec, October 2010

[6] Asmine, M.; Brochu, J.; Fortmann, J.; Gagnon, R.; Kazachkov, Y.; Langlois, C. E.; Larose, C.; Muljadi, E.; MacDowell, J.; Pourbeik, P.; Seman, S. A.; and Wiens, K., “Model Validation for Wind Turbine Generator Models” IEEE Transactions on PWRS, August, 2011.

[7] North American Electric Reliability Corporation, Standard Models for Variable Generation, Special Report, May 18th, 2010. www.nerc.com