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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
EDF R&D : Créer de la valeur et préparer l’avenir
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
EDF R&D : Créer de la valeur et préparer l’avenir
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
EDF R&D : Créer de la valeur et préparer l’avenir
Technical solutions to enable DG integration
Which interactions between actors for the controlability?
Observability for both TSO and DSO
EDF R&D : Créer de la valeur et préparer l’avenir
The Voltage and VAr control issue in MV networks
Vmax
Vmin
Voltage
Feederlength
MV
TSODSO
P
Q
EDF R&D : Créer de la valeur et préparer l’avenir
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
EDF R&D : Créer de la valeur et préparer l’avenir
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
EDF R&D : Créer de la valeur et préparer l’avenir
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
EDF R&D : Créer de la valeur et préparer l’avenir
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
EDF R&D : Créer de la valeur et préparer l’avenir
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)
EDF R&D : Créer de la valeur et préparer l’avenir
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!