Greet Vanalme – NL – RIF Session 6 – Paper 0786

Frankfurt (Germany), 6-9 June 2011

Greet Vanalme – NL – RIF Session 6 – Paper 0786

The introduction of local system services – the case of storage in the low voltage network

Yoush van Vlimmeren, University of Technology Eindhoven; Greet M.A. Vanalme, University of Technology Eindhoven; Geert P.J. Verbong, University of Technology Eindhoven;

Martijn Bongaerts, Alliander; Wil L. Kling, University of Technology Eindhoven



Contents

• Introduction• Local system services• Fitting local system services in the market• Case study: local system services using locally

available storage• Conclusions



Introduction

Socio-economic trends• Renewable energy sources ↑ • New loads: E-cars, heat

pumps

Challenges electricity system• Unbalance ↑• Local congestion ↑

Research topic: Local system services (LSS)LSS use locally available flexibility

(e.g. CHP, flexible load, storage,…)

Problem definition

Current system services might become insufficient

!

TSO

DSO



Local system servicesLocal for local Local for global• Voltage control• Network alleviation• Island or micro grid operation• Right-through capability• Local balance control

• Provide unbalance power• Reduce installed generation

capacity• Reduce network losses• Improve network efficiency• Contribute to global balance

control

Local for local: location of LSS supplying devices important Local for global: need of large number of devices + effective control



Fitting LSS in the market

Actor Possible impact of LSSConsumer Cheaper energy in exchange of flexibility, privacy

issues

TSO More complexity

DNO May offer additional services (DNO → DSO)

BRP Local balance control might assist global balance

Supplier As contact to consumer: new contracts

Regulator New legislationService company

May offer services (buying/ selling energy, selling flexibility, …)



Fitting LSS in the market - barriers• Technical challenges

• Effective, reliable and secured control & communication

• Legislation• Requirements for suppliers of system services

(minimum 5 MW unbalance power, 100% availability, direct control by TSO, registration and bidding needed at TSO level)

• Tariff structure DSO

• Established routines• Main actors have no direct need for LSS• …



Case study: LSS using storageIntroduction• LSS in residential area,

local congestion management + balance keeping

• Using storage (+) promising new technology, with little intrusion in consumer’s comfort(-) expensive strategies where storage can address several markets /

fulfil several system services are studied

• Simulations for 3 configurations• Electric heat pump + E-car for each house• E-car + PV for each house• CHP, electric heat pump, E-car and PV for 50% of houses



Case study: LSS using storage

Place storage

Control level

Control strategy Simulation name

Every house

Residential Difference in tariffs: day-night, feed-in –extraction,…

(none)

Household responds on signal sent by integrating party if beneficial.

Houses, price

Every house

Central APX driven (none)Service driven Houses, direct

Substation Central DSO control Central, direct

Substation Central Commercial control Central, price

Control strategies of storage in residential area



Case study: LSS using storageSimulations: Control of storage device

Storage controller

Signal converter

Direct (-1/0/1) or price based stimulus signal

Loading transf.

Unbalance

Energy price

Storage power




eHP + E-car E- car + PV MixtureNo control 1030 hours 17 hours 0 hoursHouses, direct 650 hours 0 hours 0 hoursHouses, price 630 hours 7 hours 0 hoursCentral, direct 930 hours 26 hours 0 hoursCentral, price 930 hours 9 hours 0 hours

Yearly transformer overloading (hours)

Simulation results

• Beneficial effects on transformer loading

• Distribution networks with a high degree of utilisation (e.g. eHP+ E-car) less suitable for providing LSS




Tran

sfor

mer

load

ing

[kW

]

No storage

With storage

Tran

sfor

mer

load

ing

[%]

No storage

With storage

Simulation results: transformer loadingDirect control

• Reaction of storage on unbalance signal extra peaks in transformer loading

• Price signals induce peak shaving

Price based control


Simulation results: summary• Beneficial effects on transformer loading, voltages and losses within

LV network

• Distribution networks with a high degree of utilisation (e.g. eHP+ E-car) are less suitable for providing LSS

• Possible transformer overloading due to unbalance signal solution: prioritize congestion signal

• Price signals induce peak shaving

• Interference between market and congestion signals reduces the responsiveness of the storage units





Case study: LSS using storageInstitutional embedding – actor tasks and responsibilities

Control Consumer DNO BRP Regulator

Houses, direct

- Own storage- Allow control

- Send network signal - Measure response

Send BRP signal

Allow tariff change

Houses, price

- Own storage- Set price threshold

Central, direct

(none) Own storage Send BRP signal

Allow storage ownership by DNO

Central, price

(none) Send congestion signal Own storage

(none)



Conclusions• LSS for “for local” (network alleviation, voltage control,…): suitable

but• No incentive for DSO• Adaptation of tariff system needed• Storage expensive

• LSS for “for global” (access to high value markets): more barriers• More complex control scheme needed• More legislative barriers• Actors have no need to implement

Documents

Greet Vanalme – NL – RIF Session 6 – Paper 0786