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Ancillary services from wind power plantsResearch results

Sørensen, Poul Ejnar; Cutululis, Nicolaos Antonio; Hansen, Anca Daniela; Altin, Müfit; Zeni, Lorenzo;Basit, Abdul

Publication date:2014

Document VersionPeer reviewed version

Link back to DTU Orbit

Citation (APA):Sørensen, P. E. (Author), Cutululis, N. A. (Author), Hansen, A. D. (Author), Altin, M. (Author), Zeni, L. (Author), &Basit, A. (Author). (2014). Ancillary services from wind power plants: Research results. Sound/Visual production(digital)

https://orbit.dtu.dk/en/publications/5460cc6f-0fd7-4666-9510-da7437ac6ac7

Ancillary services from wind power plants - Research results

Poul Sørensen, Nicolaos Cutululis, Anca D. Hansen, Müfit Altin, Lorenzo Zeni, Abdul Basit

DTU Wind Energy, Technical University of Denmark

Program outline

Ancillary Services: Research Results From Wind Power Plants

• Definitions and requirements for ancillary service

• Technical capabilities of wind power plants to provide ancillary services - state-of-the-art industry and R&D (simulation based) perspectives

• What are the economic incentives and barriers to providing ancillary services?

• What are the next steps for researchers, developers, system operators and turbine manufacturers to allow further penetration of wind into European grids?

Danish Smart Grid Research Network 2 2014-09-05


Definitions of ancillary services

• CIGRÉ report - overview of International Practices – definitions for ancillary services can differ significantly based on

who is using the terms. While some definitions emphasize the importance of ancillary services for system security and reliability, others mention the use of ancillary services to support electricity transfers from generation to load and to maintain power quality

• Some TSOs are including more specific types of ancillary services than others because

– differences in the definitions (above) – some of the required properties of the generation plants are

embedded in conventional power plants using directly grid connected synchronous generators.

– new ancillary service products seem to pop up in power systems with large scale penetration of renewables.



Requirements for – and types of – ancillary services

• Active power reserves (using ENTSO-E glossary) – Frequency containment reserves (FCR) – Frequency restoration reserves (FRR) – Replacement reserves (RR)

• Properties required to maintain power system stability today (Energinet.dk terminology)

– Short-circuit power – Continuous voltage control – Voltage support during faults – Inertia

• Possible additional ancillary service products (research references) – Fast frequency response (and inertia support) – Synchronising power – Power oscillation damping – Black-start capability



State of the art technical capabilities in industry

• Horns Rev 2002 (Kristoffersen et.al.) according to first DK technical requirements

– Primary frequency control – Secondary frequency control – Reactive power neutral

• Today +

– Continuous voltage control – Voltage support during faults – “Inertia” under development – verification?


Cost and value of ancillary services Nicolaos A. Cutululis – DTU Wind Energy Herning, 26 March 2014

© Juw

i Solar G

mbH

RESERVICES CONSORTIUM www.reservices-project.eu

Sharon Wokke Project Manager European Wind Energy Association Rue d’Arlon 80 1040 Brussels (Belgium) Tel: 0032 2 213 18 39 [email protected]

http://www.reservices-project.eu/

mailto:[email protected]

REserviceS work overview

WP2 System Needs

for AS

WP5 – WP6 Case Studies

WP3 – WP4 Capabilities and Costs

• List of services

• System impacts at large VG penetrations

• Cost structure definition

• Procurement survey

• AS costs of non VG generation

• WP3 Wind – WP4 Solar PV

• Tool: framework of functionalities / at different plant levels

• tech. specifications (GCR etc.)

• Verification of capabilities and costs: industry enquiry

• Impacts of variability and predictability

• Costs estimation

• AS provision in Transmission (frequency) and Distribution (voltage)

• Amounts of services, plant capabilities, system impacts, economic benefits, CBA

• Different system types and sizes

• In challenging SNSP scenarios: high % of wind / solar PV

8 2014-09-05 Danish Smart Grid Research Network

• Results from three case studies: – Ireland – based mainly on the results from several multi-year

research programmes (Facilitation of Renewables and DS3); additional investigation of SS costs

– Iberia – using WILMAR, 6 reg. for ES and 1 for PT; all thermal units represented (no aggregation); some agg. for hydro; VG agg. per region

– Europe – 10 countries around North Sea and Baltic; based on TWENTIES scenarios; focus on cross border sharing of frequency reserves

Transmission case studies

9 2014-09-05 Danish Smart Grid Research Network

Benefit of VG in frequency support (cases have different assumptions)

2014-09-05 Danish Smart Grid Research Network 10


EASEWIND

• Long title: – Enhanced Ancillary Services from Wind Power Plants

• Objective

– to develop technical solutions for enabling wind power to have similar power plant characteristics as conventional generation units.

• Funding: ForskEL

• Consortium:

– Vestas Technology R&D – DTU Wind Energy – DTU Compute – AAU IET



Ancillary services from wind power plants

12

The ancillary services from wind power plants are supported by communication and control at the power plant level.

2014-09-05 Danish Smart Grid Research Network


13

Simple generic wind power plant model follows the basic structure of the IEC standard Type IV wind turbine model

includes additional adjustments to reflect the dynamics relevant for active power and grid frequency control capabilities.

Pitchcontroller Aerodynamic Mechanical

model

Staticgenerator

Wind speed(CorWind)

P, Q measurements

P control

Q control

v

vFilter

MPPT Power referenceselection

LVRT

wtWPPCP

Optimal speedreference

Wind speedfilter

filtgen _ω

refgen _ω

filtgen _ω

Estimatedavailable power

filtgen _ω

wtMPPTP

wtrefP

wtmeasP

wtmeasP

wtmeasQ

wtrefQwt

WPPCQ

wtrefP

wtavailableP

Pcmdi

Qcmdi

wtaeroP

wtmeasP

rotω

θ

filtgen _ω



Wind speed 0.6pu

Short-term overproduction capability Wind speed 0.93pu Wind speed 1.1pu

Below rated wind speed, the overproduction is followed by recovery period

The higher the wind speed, the shorter the recovery period

The higher the overproduction power: the longer the recovery period and the larger the power underproduction -> frequency stability might

be affected the higher the shaft torque -> high mechanical stress of the turbine

No power recovery needed above rated wind speed

0 5 10 15 20 25 30 35 400.2485

0.249

0.2495 Aerodynamic power [pu]

0 5 10 15 20 25 30 35 40-0.005

0

0.005ωgen - ωrot [pu]

0 5 10 15 20 25 30 35 40-1

0

1

Time [sec]

Pitch Angle [deg]

0 5 10 15 20 25 30 35 400.2

0.25

0.3

Electrical power [pu]

0 5 10 15 20 25 30 35 400.8

0.85

0.9 Rotor Speed [pu]

0 5 10 15 20 25 30 35 400.2

0.25

0.3

0.35

0.4Shaft Torque [pu]

0 5 10 15 20 25 30 35 400.6

0.8

1 Aerodynamic power [pu]

0 5 10 15 20 25 30 35 40-0.06-0.04-0.02

00.02

ωgen - ωrot [pu]

0 5 10 15 20 25 30 35 40-1

0

1

Time [sec]

Pitch Angle [deg]

0 5 10 15 20 25 30 35 400

0.5

1


0 5 10 15 20 25 30 35 400.70.80.9


0 5 10 15 20 25 30 35 40-0.5

00.5

11.5 Shaft Torque [pu]

0 5 10 15 20 25 30 35 400.8

1

1.2

Aerodynamic power [pu]

0 5 10 15 20 25 30 35 40

-0.01

0

0.01

ωgen - ωrot [pu]

0 5 10 15 20 25 30 35 4002468

Time [sec]

Pitch Angle [deg]

0 5 10 15 20 25 30 35 400.9

11.11.2


0 5 10 15 20 25 30 35 400.95

1


0 5 10 15 20 25 30 35 40

1

1.2

1.4 Shaft Torque [pu]



15

Wind power plant control architecture



Enhanced ancillary services


WPP Active or Reactive Power output POD controller

PODQ∆I

P PODP∆

Active Power or Current Magnitude

time

time

IR controllerIRP∆f∆

dtdf /

1pu Grid Frequency

time

P

time

WPP Power Output∆

SP controllerSPP∆δ∆

θ∆

Load Angle

Time

WPP power output

Time


WPP Inertial response capability

5 10 15 20 25 30 35 400.98

0.985

0.99

0.995

1

1.005

[pu]

Grid frequency

Without IRWith IR

5 10 15 20 25 30 35 400.2

0.21

0.22

0.23

0.24

0.25

0.26

0.27

0.28

0.29

[pu]

WPP power

5 10 15 20 25 30 35 40

0.856

0.858

0.86

0.862

0.864

0.866

[s]

[pu]

Gen. speed5 10 15 20 25 30 35 40

-1.25

0.00

1.00

2.00

3.00

4.00

5.00

[deg

]

Pitch angle



WPP synchronise power capability

δ∆

0 5 10 15 20 25 30 35 40350

400

450

500

550Load change

[MW

]

0 5 10 15 20 25 30 35 405

10

15

20Rotor angle deviation

[deg

]

0 5 10 15 20 25 30 35 40340

360

380

400WPP power

Time [s]

[MW

]

Without SPWith SP


OffshoreDC


OffshoreDC

WP 3 – Communication and control in clusters of wind power plants

connected to offshore HVDC grids PhD student: Lorenzo Zeni

OffshoreDC Results – status

L. Zeni et.al. From paper in Cigré session 2014


21

VDC,1

VDC,WPP

VDC,2

P1,Q1 P2,Q2

P,Q P,QSG1 SG2

0.5*Zline 0.5*Zline

PWPP,QWPP

P,Q

Grid 2

Grid 1

VSC1 (w chopper)

VSC2 (w chopper)

Bus 1 Bus 2Bus 3

Investigation on system services provision

Onshore AC voltage control and LVRT

Onshore frequency control and power

oscillation damping

Offshore network control

Important results obtained and lines for future work were drawn.

DC voltage control

OffshoreDC

Two strategies are compared: 1. Communication-based control (with communication delay) 2. Coordinated control mirroring the frequency in DC voltage


Frequency support through HVDC P2P example

OffshoreDC On the inertial contribution


0 2 4 6 8 100.35

0.4

0.45

0.5

A2

- Pre

f [pu]

0 2 4 6 8 100.35

0.4

0.45

0.5

B2

- Pre

f [pu]

Time [s]

(a)

(b)

(b)

(a)

Power reference to WPP (a) From controller (b) Ramp-limited

Communication

Coordinated control

The initial power support is heavily limited by the ramp limiter (0.1 pu/s): relaxation of this figure?

OffshoreDC Conclusions

• Onshore frequency variations can be mirrored offshore • Hence, WPPs can provide frequency control through

HVDC with communication-less scheme • Fast control actions are inhibited by ramp rate limiters in

the WPP • In a P2P connection, communication-based and

coordinated solutions are equivalent, as far as frequency control and inertial response are concerned


25

Consortium and budget

Spain (5) RED ELECTRICA DE ESPAÑA IBERDROLA ITT COMILLAS GAMESA ABB S.A.

Belgium (6) ELIA SYSTEM OPERATOR EWEA CORESO UNIVERSITY LIEGE UNIVERSITY LEUVEN UNIVERSITE LIBRE BRUXELLES

Denmark (3) DONG ENERGY ENERGINET DTU ENERGY

France (2) RTE EDF

United Kingdom (2) ALSTOM GRID UNIVERSITY OF STRATHCLYDE

Germany (3) FRAUNHOFER IWES 50 HzT SIEMENS Wind Power

Italy RSE

Ireland UCD

The Netherlands TENNET Portugal

INESC-PORTO

Norway SINTEF

Total budget: 56.8 M€ EU contribution: 31.8 M€

10 European Member States 1 Associated Country

Danish Smart Grid Research Network

26

Demo 4 - The challenge

Danish Smart Grid Research Network

0° 15° E

60° N

Synchronous Area

2020 2030

MW MW

Continental 21,421 57,685

Nordic 4,924 14,669

GB 13,711 33,601

Ireland 1,419 3,219

2030 map


• There must be sufficient primary reserves in the power system synchronous area to replace lost production corresponding to dimensioning fault

• This brings power system from normal state to alert state

• Frequency restoration (secondary / tertiary) reserves will return system to normal state in 15 minutes

• Larger faults (loss of generation) may bring system into disturbed (or emergency) state

• Therefore, maximum 15 minute wind power forecast errors are essential to esure adequacy of primary reserves

Large scale challenge: Adequacy of primary reserves


Nordic grid code 2007

Synchronous Area Dimensioning faultt MW

Continental 3,000 Nordic 1,200 GB 1,800 Ireland 500


• Result for 2020 indicates that there is sufficient primary reserves with current dimensioning fault to cover offshore wind power variability in the four main European synchronous areas

• Result for 2030 indicates that there is not sufficient primary reserves with current dimensioning fault to cover offshore wind power variability in Continental and GB synchronous areas

• PhD poster (Kaushik Das) on more detailed assessment in EU iTesla project

Upscaling results and conclusion


Synchronous Area HWSD HWEP Dimensioning faultt

MW MW MW Continental 4,729 3,933 3,000 Nordic 1096 1082 1,200 GB 4,418 4,440 1,800 Ireland 439 438 500

Synchronous Area HWSD HWEP Dimensioning faultt

MW MW MW Continental 1,661 1,548 3,000 Nordic 480 483 1,200 GB 1,212 1,222 1,800 Ireland 224 224 500

2020

2030


Simulation of balancing (Simba)

• Simba idea – Simulation of intra hour balancing

as supplement to day ahead – Uses inputs from “day-ahead

market model” – Main imbalance included today is

from wind • Applications of Simba

– Planning of investment – Assessment of new market

designs (e.g. towards real time) – Assessment of cost / value of

reserves – Assessment of needs for reserve

capacities – Economic optimisation of system

services – Assessment of flexible demand

support to system balancing


Import Export

Simulation of Balancing (Simba)


CorWind Simulation of wind power fluctuations and forecast errors


0

200

400

600

800

1000

1200

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00

Offs

hore

win

d po

wer

in D

enm

ark

[MW

]

8 November 2020

P_W_RTP_W_DAP_W_HA


Modelling chain: Spot market – balancing – automatic frequency control


Spot market model

Wind generation patterns model (CorWind)

Balancing model

(Simba)

PWind,DA[1h] PWind,HA[5m] PWind,RT[5m]

Psched,DA[1h] Automatic control model

Pplan,HA[5m]

Power system scenario


Automatic Generation Control in a power system with high wind power penetration – Danish case study

32 Danish Smart Grid Research Network

2014-09-05

fnominal

factual BACE PI

controller ∆Pset

pfCHP+ -

PCHP

++

PLOAD

PDCHP

Pexchange

Pwind

∆P

∆f/R

PGEN

-

-

-+

∆PDCHP+

++

+90 MW

-90 MWpfDCHP

∆PCHP

AGC model Model overview

Result: simulated AGC performance


Wind Power integration into the Automatic Generation Control of power systems

33 Danish Smart Grid Research Network

2014-09-05

Aggregated Wind Turbine modelSimBa

Frequency droop

Fmeasure

Wind Power Plant

Controller

Pref_WT

Pavailable

Pref

Pmeasure

Active power

Controller

Static Generator

ip_cmd

Pmeasure

AGC

+

+

Pref (freq)

ΔP_WF∆Pset

∆P > dP_avail

|∆P| < |curtailing|

∆P < 0

dPavailable

Curtailing Power

yes

no

yes

yes

no

no

∆P_WF = ∆Pset∆P_CHP = 0

∆P_WF = -1*|curtailing|∆P_CHP = |curtailing| -|∆Pset|

∆P_WF = dP_avail∆P_CHP = ∆Pset - Available

∆P_WF = dP_avail∆P_CHP = 0

Aggregated WPP model Secondary (AGC) dispatch with wind

More details in poster

Abdul Basit


Summary and reflections on technical capabilities • WPPs can provide basic ancillary services and replace conventional

power plants • Also possible to provide enhanced ancillary services – emulating

synchronous generators (inertia-like response, power oscillation damping and synchronizing power)

– … but is this the optimal solution in future systems? • Ancillary services can also be provided from HVDC connected WPPs

34 Danish Smart Grid Research Network 2014-09-05


Economic incentives and barriers • Incentives:

– Technical requirements for grid connection! – Higher prices for reserves than for power (e.g. low – and even

negative power prices) – Co-generation with other production technologies (ramp support) – Enables higher wind power penetration

• Barriers: – Symmetric (up/down) requirement (Spain – TWENTIES)

• Downwards reserves from WPPs is feasible with high penetration

• … loads are more feasible as upwards reserves – Length (= prediction horizon) of reserve products – Development costs for new products – Additional hardware costs – Verification needs for new products –certification costs



TPWind Technology Platform New strategic research agenda (SRA) / Market deployment strategy 2014 • Issues – very similar to REserviceS

– Frequency support – Voltage support – System restoration support

• Research priorities – Further development of enhanced wind power capabilities from

wind turbine level up to cluster level, including the related design tools and models;

– Testing and verification of frequency and voltage capabilities, and methods of proving compliance of new solutions for advanced capabilities with Grid Codes and standards;

– Harmonisation, standardisation and interoperability of methods and technologies for delivering ancillary services with wind power.



Next steps to allow further penetration of wind into European grids? • Researchers

– Propose strategies for ancillary services from wind and other sources to ensure system stability with massive scale wind power

• Special focus on power system security with increasing levels of non-synchronous generation

• Not necessarily emulation of synchronous generators – other smarter solutions!!

– Develop and implement new controls in simulation tools – Simulation based validation of ancillary services from wind – Develop tools to assess the value of new ancillary services

• Developers / owners – Assess the value of new ancillary services

• System operators – Validate and implement strategies to ensure system security

• Turbine / plant manufacturers – Develop and implement new ancillary service capabilities in full

WPP scale 37 Danish Smart Grid Research Network 2014-09-05

ancillary services from wind power plants research results · ancillary service products (research...

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