Wind Power Grid Integration - Grid Code Requirements ... · PDF fileWind Power Grid Integration - Grid Code Requirements & Compliance Schemes The German Case – Lessons and Experiences

Wind Power Grid Integration - Grid Code Requirements & Compliance Schemes The German Case – Lessons and Experiences

Dipl.-Wirt.-Ing. Julian Langstädtler / FGH – Certification Office Dipl.-Wirt.-Ing. Frederik Kalverkamp / FGH – Certification Office

TECHWINDGRID 2011 Madrid, Spain, 14 DECEMBER 2011

FGH comprises: FGH Certification: Certification of power generation units (e.g. WTG) and

power generation clusters (e.g. wind farms) Calculation of power generation clusters‘ electrical behaviour Validation of simulation models

FGH Power Equipment Technology: Studies in IEC 61850 Smart Grids‘ primary and secondary Infrastructure

FGH System Studies: Research Projects focused on system stability Exp.: Effects of the shut-down of nuclear

power plants for the German Government

FGH Test Systems: LVRT-Test laboratories (test container)

Scientific Studies in cooperation with German universities and leading manufacturers; participation in national and international working groups (IEC, IEEE, EWEA, FGW, FNN…); global collaboration

1

FGH Research Association for Power Systems and Power Economics – At a glance

Wind Power Grid Integration - Grid Code Requirements & Compliance Schemes Langstädtler | FGH – Certification

2

Motivation of Modern Grid Codes

Structural Changes in Electric Power Systems

Past Concepts: Power Supply by large & central Plants Mainly directed Power Flow from high to low

voltage levels

Today & in Future: Increasing dispersed Power Generation

Substitution of Conventional Power Plants

Bi-directional Power Flow

Increasing trans-European Tradings

Adaption of Infrastructure (primary and secondary Technologies)

Admission of DER in System Control – Provision of Ancillary Services

Definition of Requirements wrt. the Electrical Characteristics of DER

110 kV

380/220 kV

20/10 kV

0,4 kV

Netzebene

CHP

H2O

V2G

Druck

€, kWh

Revision of Grid Codes mandatory


Need for System Operators to involve RES

Status of the energy supply where renewables have been highly promoted

3

Problems of the system operator

Frequency stability Voltage regulation Dynamic operation

• Lacking involvement of RES in balancing power oscillations

• Substitution of conventional power stations with reactive power supply

• Danger of deficit in power supply after fault clearance in case of disconnection

Increasing penetration of RES

Postulation of system services is mandatory


0,00

0,50

1,00

1,50

2 4 6 8 10 12 14 16 18 20 22 24

Cu

rren

t [A

]

Order

Harmonics

0

2

4

6

8

10

12

14

16

18

20

-6 -4 -2 0 2 4 6

Wir

kle

istu

ng

P [

MW

]

Blindleistung Q [MVAr]

Anlagenkennlinie am NAP Anforderung nach BDEW MS-RL 2008a

übererregter Betriebuntererregter Betrieb

Contemporary Grid Code Requirements for Wind Power

4

Grid Code requirements:

Active Power

Reactive Power

System perturbation

Protection Concepts

Fault Ride Through (FRT)


Requirements: Active Power Reactive Power Supply System Voltage Disturbances Protection Concept Behavior during Grid Faults

Renewable Energy Law (EEG)

(§ 6 Nr. 2; § 29, IV, 2; § 66, I, Nr.6)

Ordinance for System Services (SDLWindV)

(§ 2, 3, 6, 8)

Transmission Code (HV)

Medium Voltage Directive (MV)

Grid Codes of DSOs/TSOs

5

Technical guidelines (FGW) (Measuring (TR3), Validation (TR4),

Certification(TR8))

Grid codes required by law

Objective of Certification: Calculation of wind farms electrical caracteristics at the PCC and test of conformity according to Grid Codes (unit & cluster certification)

FGW: German Wind Energy association

Law, Grid Codes & Technical Guidelines in Germany


Classification of Wind Turbines according to SDLWindV

Deadlines for fulfillment depending on dates of commissioning

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Type A Commissioned until 31.12.01

Type B Commissioned between 01.01.02 and 31.12.08

Type C Commissioned between 01.01.09 and 30.06.10*

Type D Commissioned between 01.07.10 and 30.06.11

Type E Commissioned between 01.07.11 and 31.12.13

Type F Commissioned after 01.01.14

SDL Requirements

No Optional – without TC Specificatiion

Optional – without TC Specificatiion

Mandatory – without TC Specificatiion

Mandatory – with TC Specificatiion

Mandatory – with TC Specificatiion

SDL-Bonus if requirement fulfilled and testified

No Yes, testified per Expertise

Yes, testified per Expertise / Certificate




Bonus No Bonus 0,7 ¢ / kWh 0,5 ¢ / kWh 0,7 ¢ / kWh 0,7 ¢ / kWh

Deadlines - 31.12.2010 31.12.2010** Instantly Instantly Instantly

Frequency Control LVRT-Capability

Frequency Control LVRT-Capability Dynamic Behavior Voltage Regulation


* delayed: 31.03.2011

**delayed: 30.09.2011

Implementation of Grid Code Requirements

Retrofit activities to improve the system reliability

Fulfillment of system services by upgrading existing turbines depending on their commissioning

Definition of most important requirements for basic performance

FGH has certified more than 2 GW so far

7

45%

55% 99%

1%

15 GW – intermediate turbines (2002-2008)

5 GW – transition turbines (2009-2011)

potential

retrofitted

Retrofitting has economically been beneficial for most projects


Impact of Retrofitting on Wind Power Industry

Effort to meet specific grid code requirements

8

0

0,5

1

1,5

2

2,5

3

Durchfahren von Netzfehlern ohne

Netztrennung

Verbleiben am Netz bei Netzfrequenzen

zwischen 47,5 Hz und 51,5 Hz

Wirkleistungsreduktion bei Netzfrequenzen

über 50,2 Hz

Blockierung der Wiederzuschaltung auf Anforderung

Sonstiges

Vollumrichter 1 DFIG1 DFIG2 Vollumrichter 2

Power

reduction at

overfrequency

Blocking of

Reconnection

on demand

Miscellaneous

LVRT

Remain

connected at

wide frequency

range

FC1 FC2 DFIG1 DFIG2

Value Effort Comment

1 small Software Update or new

parameter setting without any replacement of hardware

1,5 small/

medium

Replacement of small hardware components

(e.g. relay)

2 medium

Existing hardware is modified with additional devices (e.g. chopper design)

2,5 medium/

high

Many hardware components are changed and substituted

3 high

Replacement of old devices with new components that

changes the design considerably

(e.g. generator, converter)


9

General Approach of Wind Farm Certification

Validation (FGW-TR4) = Analysis of Deviations between Unit Model and Field

Test Results (P, Q, Ib)

Representing failure behaviour via dynamic Simulation

Validated Model

+

Wind farm

Grid Data

Dynamical Calculation of Wind Farms‘ Performance

at Voltage dips

Unit Model Unit‘s measurement (field test) FGW-TR3

Representing failure behaviour in Field Test

Active Power Control Reactive Power Control System Pertubations Protection Settings etc.

Unit

Calculation of Wind-Farms Characteristics based on Unit‘s Data

Comprehensive Compliance Test acc. to Grid Code

Requirements (FGW-TR8)


Calculation methods Dynamic Stability Analysis

FRT Field Tests for units…

… are performed on Wind Farm-level using validated models:

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Medium

Voltage Grid

Current

Limiting

ReactorVariable

Reactor

controlling the dip‘s depth

Controlled

Circuit Breaker

X1

X2

X3

S

WECWEC

Transformer

Medium

Voltage Grid

Current

Limiting

ReactorVariable

Reactor

controlling the dip‘s depth

Controlled

Circuit Breaker

X1

X2

X3

S

WECWEC

Transformer

~ (Source: Zertifizierungsstelle der FGH e.V., Z 310)

(Field Tests with the FRT-container of FGH Test Systems GmbH)

Setup developed at FGH

Incorporated in

IEC 61400-21 measurement directive

Base for unit certification and calculations of the electrical caracteristics of the whole wind farm

Wind Farm Cluster: 1…n Units


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Mixed wind farm constellations:

Many different constellations possible:

In these cases results of dynamic stability analysis are only approximately resilient!

Calculation methods Dynamic Stability Analysis

Unitnew

P.C.C.

Unitold Unitold Unitold Unitnew Unitnew

Prototypes (no models)

Units with sym. models

Units with sym./asym.

models

Old units with LVRT-capability

(no models)

Old (tripping) units (no models)


12 12

Required reactive

current deviation ∆IB

[p.u.]

dead band

Ud = +/- [0%..10%] Un

1.0

Limitation of the voltage by voltage

control (underexcited operation)

Voltage drop or

increase ∆U [p.u.] 0.5 0.3 - 0.3 - 0.5

- 1.0

Representation in reference variables:

Reference voltage is Vn

Reference current is In

Back-up of the voltage control

(overexcited operation)

Injection of Additional Reactive Current according to SDLWindV

0 ≤ K ≤ 10

K determined by DSO/TSO !

Requirements on Dynamics:

Response-Time: 30 ms Settling-Time: 60 ms

Exemplarily Crucial Grid Code Requirements Dynamic Voltage Support

= K ∙

∆IB

In

∆Ur

Un

High values of K can lead to critical voltage oscillations

K<1 can lead to instabilities


ENTSO-E Pilot Network Code

Lessons from the German Case

Transition periods have been tight and deadlines had to be postponed several times

Lack of clearly defined requirements

Guidelines for testing and proving of grid code compliance have been developed during the transition periods Modifications and clarifications deferred the certification process

Heterogeneous principles in the assessment of wind farm bahavior (inconsistent evaluation by different certification bodies)

Retrofitting was an enormous effort of whole industry System Operators often do not make usage of all system services provided by

wind power plants (especially in medium voltage level)

Lacking information about turbine‘s behavior (=> confidentiality)

Focus may be more on ancillary services instead of compulsory technical requirements (provide what/where/when it is needed)

13 Wind Power Grid Integration - Grid Code Requirements & Compliance Schemes Langstädtler | FGH – Certification

Conclusions and International Context

Grid Code compliance (certification) needed to ensure System Stability with increasing number of WTG in the future

Differentiation between unit and cluster certification

Validated models are essential for dynamic stability analysis and detailed represenation of wind farm is needed for correct verification of protections

Recommendations for verification of grid code compliance in future Sufficient time for transition periods needed

(for both technical implementation and certification procedures)

Clear definitions in Grid Codes (reference values and measurement points)

Well-defined methods and guidelines for verification and wind farm simulation

Periodical grid gode reviewing necessary to achieve the objectives efficiently

ENTSO-E‘s Pilot Network Code must take these aspects carefully into account

14 Wind Power Grid Integration - Grid Code Requirements & Compliance Schemes

Langstädtler | FGH – Certification

15 15

Thank you for your attention!


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Wind Power Grid Integration - Grid Code Requirements ... · PDF fileWind Power Grid Integration - Grid Code Requirements & Compliance Schemes The German Case – Lessons and Experiences