Operating the power system while enabling more renewables : which solutions?

Transcription

1 Operating the power system while enabling more renewables : which solutions? Sébastien GRENARD EDF R&D 22/06/2010

2 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 Transmission Network Transmission Network Distribution Network Distribution Network 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 minimisation Renewable DG to contribute to system security

3 Aggregation: a possibility for market integration of DER In today s framework most renewable distributed resources: Take benefits of feed in tariffs (they inject whenever 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 Arrival of new actors 2) For large penetrations, DG must be able to provide system and network services New contractual arrangements and services between actors Fenix project (european FP7 project)

4 Fenix project: actors interaction and architecture overview µchp µchp FB FB TRADER Aggregator 1 1 CVPP 2 SIXTH FRAMEWORK PROGRAM Sustainable Energy Systems PV WindF FB FB CVPP 1 TVPP Centralized Generation Gen Gen Gen Existing links Links created or reused for FENIX FENIX Servers Trading Software TRADER Aggregator 2 2 Market Control DMS Centers DSO TSO TSO Dispatch Centers

5 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 networks: voltage rise effect

6 Technical solutions to enable DG integration Observability for both TSO and DSO Which interactions between actors for the controlability?

7 The Voltage and VAr control issue in MV networks TSO DSO P Q MV Voltage Vmax Vmin Feeder length

8 The Voltage and VAr control issue in MV networks TSO DSO P G +/- Q G P Q MV Voltage Vmax Vmin Feeder length

9 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 parameters (Reactive power transit between DSO and TSO / Distribution network losses /.) Increase DG hosting capacity VVC MV MV LV P ±Q LV S CHP P,-Q A NOP LV P ±Q PV

10 Architecture of control centre tools for an active network Substation local measurements HMI Capacitor banks New sensors measurements DER real-time measurement SCADA Distribution State Estimation (DSE) VVC Transformers tap changer Real-time network topology Network Data, Load models Constraints Contracts (with TSO and DG) DER set points

11 New automation functions required, but not only 1) Needs for new automation algorithm and SCADA improvements Distribution State Estimation VVC Needs for sensors in the MV network + use of AMM data for load models improvement 2) Needs for clear contractual agreements between TSO/DSO/DG Which service at which costs / penalties 3) Needs for data exchange standards Data exchange between actors (current example of TSOs) Information exchange between IEDs and control centers (IEC 61850) Common Data format in control centers information system (CIM) 4) Needs for cost/benefits analysis Cost benefits analysis for DSOs and TSOs Impact on DG s investment and operating costs

12 Impact for the distributed generation (1/2) Impact of DG s participation in reactive power services Reducing the cost of connection Not necessary to strengthen the network (not systematically) Faster connection A communication between the generation and the DSO More data exchange A good interface with the DSO (CIM) But an oversize of the inverter and an increase in losses Q Scenario 1: Q = 0, Smax = Pmax Scenario 2 : Q 0, P<Pmax Scenario 3 : S max>smax, P max = Pmax P

13 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)

14 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!