Operating the power system while enablingmore renewables : which solutions?

Sébastien GRENARDEDF R&D

22/06/2010

EDF R&D : Créer de la valeur et préparer l’avenir

New environment for power systems design and operation European targets and attractive feed-in tariffs⇒ Increased deployment of small / medium renewable generation connected to the distribution networks

Actual power systems were not designed and operated to integrate a large share of intermittent and distributed generation

Requirements for new technical solutions for system security and for integration costs minimisationRenewable DG to contribute to system security

Distribution Network

Distribution Network

TransmissionNetwork

TransmissionNetwork

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Aggregation: a possibility for market integrationof DER

In today’s framework most renewable distributed resources:Take benefits of feed in tariffs (they inject whene ver they want)Are not encouraged to provide ancillary services

Two issues arising:1) With no feed in tariffs ���� market integration of small/medium Distributed

Generation requires aggregation

2) For large penetrations, DG must be able to provide system and network services

Fenix project (european FP7 project)

Arrival of new actors

New contractual arrangements and services between ac tors

EDF R&D : Créer de la valeur et préparer l’avenir

Fenix project: actors interaction and architecture overview

Cen

tral

ized

G

ener

atio

n

Existing links

Links created or reused for FENIX

DSO

FB

FB

Market

µCHP

PV

WindF

FENIX Servers

TVPP

FB

TRADER 2

Gen

Gen

Gen

CVPP 1

FBµCHP

Trading Software

TSO

DMS

TRADER 1CVPP 2

Cen

tral

ized

G

ener

atio

n

Existing links

Links created or reused for FENIX

DSO

FB

FB

Market

µCHP

PV

WindF

FENIX Servers

TVPP

FB

Aggregator 2

Gen

Gen

Gen

CVPP 1

FBµCHP

Trading Software

TSOTSO

Control Centers

Aggregator 1CVPP 2

Dispatch Centers

SIXTH FRAMEWORK PROGRAMSustainable Energy Systems

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Technical impacts of distributed renewable generation

DSOs anticipate that they can integrate only a limited capacity of DG without a major reinforcement

Limiting factors in many European distribution netw orks: voltage rise effect

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Technical solutions to enable DG integration

Which interactions between actors for the controlability?

Observability for both TSO and DSO

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The Voltage and VAr control issue in MV networks

Vmax

Vmin

Voltage

Feederlength

MV

TSODSO

P

Q

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The Voltage and VAr control issue in MV networks

Vmax

Vmin

PG

+/- QG

Voltage

Feederlength

MV

TSODSO

P

Q

EDF R&D : Créer de la valeur et préparer l’avenir

What are the solutions?

Approach with existing practise (“fit and forget”)No control over DER / Worst case scenarios used for connection sizing

Active distribution network: Coordinated control of voltage and flows (VVC: Volt VAr Control function) to:

Maintain voltage within limits and Optimise other p arameters (Reactive power transit between DSO and TSO / Distribution network losses / ….)Increase DG hosting capacity

VVC

AP,-Q

CHPS

P ±Q PV

P ±Q

LV

LVLV

MV MV

NOP

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Architecture of control centre tools for an active network

Distribution State

Estimation(DSE)

VVC

Substation local measurements

DER real-time measurement

Real-time network topology

Network Data,Load models

Constraints

Contracts (with TSO and DG)

Capacitor banks

DER set points

Transformers’ tap changer

SCADA

HMI

New sensors’ measurements

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New automation functions required, but not only…

1) Needs for new automation algorithm and SCADA improvementsDistribution State Estimation

VVC

Needs for sensors in the MV network + use of AMM da ta for load models improvement

2) Needs for clear contractual agreements between TSO/DSO/DGWhich service at which costs / penalties

3) Needs for data exchange standardsData exchange between actors (current example of TS Os)

Information exchange between IEDs and control cente rs (IEC 61850)

Common Data format in control centers information s ystem (CIM)

4) Needs for cost/benefits analysisCost benefits analysis for DSOs and TSOs

Impact on DG’s investment and operating costs

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Impact for the distributed generation (1/2)

P

Q

Impact of DG’s participation in reactive power serv icesReducing the cost of connection

Not necessary to strengthen the network (not systematically)

Faster connection

A communication between the generation and the DSOMore data exchangeA good interface with the DSO (CIM)

But an oversize of the inverterand an increase in losses

Scenario 1: Q = 0, Smax = PmaxScenario 2 : Q ≠0, P<PmaxScenario 3 : S’max>Smax, P’max = Pmax

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Impact for the distributed generation (2/2)

Impact of active power curtailments

Avoid the total disconnection of power generation

Better compromise between MW and MWh (active power curtailement only during congestions)

Such solution could be a benefit to producers but:Requirement to establish a new mechanism (contracts between actors)

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Conclusions

Technical solutions exist for the integration of intermittent distributed generation. They are based on a better observability of generators and of the network.

But technico-economic assessments are required!

Interactions between actors and an appropriate regulatory framework need to be built!