Session 13: German MV and LV Grid Code and PV/Wind Operating Experience

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1 Session 13: German MV and LV Grid Code and PV/Wind Operating Experience Dr. Dipl.-Ing. Thomas Ackermann Energynautics GmbH

2 PV/Wind Operating Experience 2

3 German Energy Policy Targets 3

4 Distributed Renewable Generation and Status Nuclear Power in Germany The German Wind/PV Power Plant End of 2013 : MW (Wind) 35,000 MW (PV) 6 August 2011, six units shut down Remaining units shut down until

5 Current status Renewables Germany: Share Renewables of total Production: 19% Source: Electricity production from solar and wind in Germany in 2013, Burger, Fraunhofer, ISE. 5

6 Peak Wind Capacity: 5th December 2013 Source: Electricity production from solar and wind in Germany in 2013, Burger, Fraunhofer, ISE. 6

7 Maximum Solar Capacity: 21 July 2013 Source: Electricity production from solar and wind in Germany in 2013, Burger, Fraunhofer, ISE. 7

8 Maximum Wind/Solar Production: 36 GW Source: Electricity production from solar and wind in Germany in 2013, Burger, Fraunhofer, ISE. 8

9 Electricity Market Germany 2013 Source: Electricity prices and production data in 2013, Burger, Fraunhofer, ISE. 9

10 Case Study of an event with negative prices (I) Source: Electricity prices and production data in 2013, Burger, Fraunhofer, ISE. 10

11 Case Study of an event with negative prices (II) Source: Electricity prices and production data in 2013, Burger, Fraunhofer, ISE. 11

12 Grid Upgrades planed in Germany 12

13 Result of Grid Upgrade for 100% Scenario in one State Base Case Optimum Case Angegebener Ausbaubedarf: zusätzlich zu geplanten Maßnahmen der Netzbetreiber, deren Umsetzung bereits vorausgesetzt ist (Umfang: rund 174 Stromkreiskilometer und 0 MVA Transformator-Leistung) Quelle: Eigene Darstellung (Energynautics GmbH) 13

14 Grid Code Issues 14

15 Grid Code Pages Source: S. Bolik German TransmissionCode 2007 (79 pages), ( > 60 kv) German Technical Guideline 2008: Generating Plants Connected to the Medium- Voltage Network (130 pages) (1 kv 60 kv) Generators connected to the low voltage distribution network Technical requirements for the connection to and parallel operation with low-voltage distribution networks (80 pages) (<= 1kV) 15

16 Grid Code Development MV Transmission Code Guideline Source: S. Bolik 16

17 Comparison Grid Codes Source: S. Bolik 17

18 The German Grid Codes/ Guidelines Grid Codes Fault Ride Through Reactive Power Supply Frequency Band Active Power Derating Extra/High Voltage (> 60 kv) Method U, cosφ, Q Limitations Q/P n and voltage level (3 different variants) 47,5 Hz 51,5 Hz P % ( ) 40 (50,2 Hz f ) P Hz M 50, 2Hz f 51,5 Hz Medium Voltage (<= 60 kv & >1 kv) Method Q(U), cosφ fix, Q fix, cosφ(p) Limitations 0,95 underexcited to 0,95 overexcited 47,5 Hz 51,5 Hz P % ( ) 40 (50,2 Hz f ) P Hz M 50, 2Hz f 51,5 Hz Low Voltage (< =1 KV) Method cosφ fix, cosφ(p) Limitations s 0,90 un to 0,90 ov 0,95 un to 0,95 ov s E MAX E MAX 47,5 Hz 13,8kVA 51,5 Hz 13,8kVA P % ( ) 40 (50,2 Hz f ) P Hz M 50, 2Hz f 51,5 Hz 18

19 Active Power Control (1) A reduction of active power must be possible in steps of 10%. The network operator sends a new setpoint in case of: Risk of unsafe system operation Risk of bottlenecks Risk of unwanted islanding Risk of grid instability Repairs or constructions

20 Active Power Control (2) Power reduction due to overfrequency Source: BDEW

21 Active Power Control (3) Conclusion: Requirements can easily be fulfilled by a PV system: New control scheme has to be included in each inverter. Communication based solution (sending setpoints) is too slow to react fast enough on disturbances in the power grid. Controller design, certification process and tests can be supported by models and simulations.

22 Static Grid Support (1) Voltage support under normal operation Provide reactive power: cosφ = 0.95 underexcited to 0.95 overexcited Setpoint can be fixed or adjustable: Fixed displacement cosφ Variable displacement factor cosφ(p) Fixed reactive power in Mvar Variable reactive power Q(U)

23 Static Grid Support (2) Example: cosφ (P) Source: BDEW

24 Fault Ride Through Solution Grid Codes Issue: Not all CCGT & Nuclear power stations can fulfill the same grid code Source: E.on 24

25 Behaviour in the event of network disturbances (transmission code) 25

26 German Grid Code Definition A type 1 generating unit exists if a synchronous generator is directly connected to the network. A type 2 generating unit exists where this condition is not fulfilled. 26

27 Behaviour in the event of network disturbances (MV Guideline) Fault-Ride-Through (PV systems) Source: BDEW

28 Dynamic Voltage Control Source: BDEW

29 Model Validation Procedure Proof of grid code compliance for wind turbines by Product Type Certificates Single wind turbine: by measurement But how to check grid code compliance of wind power plants? 29

30 Proof of Grid Code Compliance: Wind Power Plants Measurement of electrical characteristics difficult because of high generating capacities of wind power plants Measurements only possible after commissioning Different types of wind turbines involved Wind power plant internal grid configurations Additional devices (SVC, STATCOM,..) Wind farm controllers (P,Q, FRT,..) Compliance has to be proofed by simulations Need for validated models of wind turbines! 30

31 The 50.2 HZ Grid Code Problem 31

32 Frequency threshold for disconnection The 50.2 HZ Problem in Germany: Several thousand megawatts of DG disconnect at unfavorable frequency Germany Reasons Underestimation of DG development Slow grid code updating Missing coordination between DSOs and TSOs Biogas Wind power 0 10,000 20,000 30,000 40,000 50,000 60,000 Small hydro power (<1 MW) Photovoltaic MW Small hydro power (1-10 MW) Combined Heat & Power as of end Source: EEG-registry of TSOs ( ) and Federal Netzwork Agency ( ) Source: ECOFYS

33 The European problem is even worse. Only 3,000 MW of primary reserve are available in Continental Europe. Frequency threshold for disconnection ,000 20,000 30,000 40,000 50,000 60,000 Germany Spain Italy France Netherlands Poland Denmark as of end Source: EEG-registry of TSOs ( ) and Federal Netzwork Agency ( ) MW Source: ECOFYS Source: ENTSO-E 3,000 MW Primary reserve in Continental Europe

34 The combined probability of a blackout is very low, but it would have tremendous effects. Network frequency histogram % f 49.9 Hz for approx. 2.5 hrs f 50.1 Hz for approx. 2.6 hrs Recent large-scale disturbances with f 50.2 Hz: Italy (2003) Germany (2006) f [Hz] Source: IFK, University of Stuttgart (2011) ECOFYS Jens C. Boemer 6/24/

35 Outlook: European Network Codes 35

36 36 European Network Codes in a nutshell Why are Requirements for Generators (RfG) urgently needed? Connection Codes Make new units future-proof: Setting appropriate capabilities in new generation ensure markets can deliver and systems can be operated in future. HVDC RfG Avoid future regret & retrofits. CP DCC Balance European settings and regional specificities by a mix of exhaustive and non-exhaustive requirements. EB Network Codes Further specifications by transparent and appropriate national procedures are a key element for successful implementation. FCA CACM OPS LFCR OS EP

37 Framework Guidelines and corresponding Network Codes Mandate (RfG) Mandate (DCC) Network Codes Grid connection requirements for generators Grid connection requirements for Demand Connection Q3/2012 Q1/2013 Grid connection procedures Grid connection requirements for HVDC links Q4/2013 Q1/

38 For more information on the details and current status of the ENTSO-E Network Codes, see 38

39 Appendix 39

40 Network disturbances Power quality has to be assured! Sudden voltage change due to connection or disconnection of generators must be below 2% Long-term Flicker depends on impedance angle and wind speed. It s strength must be below 0.46 Harmonics and inter-harmonics Commutation notches Ripple-control Source: BDEW MV Grid Code

41 Example: Connection of an 800 kw photovoltaic power plant (I) 41

42 Example: Connection of an 800 kw photovoltaic power plant (II) Calculation of the network short-circuit power SkV at the network connection point; Specifications of the network operator concerning the network connection; Check-up of the admissible voltage change according to Section 2.3; Check-up of the dimensioning of network equipment according to Section 2.2; Check-up of the network repercussion Sudden voltage change ; Check-up of the network repercussion Long-term flicker ; Check-up of the network repercussion Harmonics and inter-harmonics Check-up of the impact on audio-frequency ripple control systems. 42

43 Example: Connection of a 20 MW wind farm (I) 43

44 Example: Connection of a 20 MW wind farm (II) Check-up of the rated power of equipment according to Section 2.2; Check-up of the network repercussion Sudden voltage change ; Check-up of the long-term flicker network impact; Check-up of the network impact Harmonics and inter-harmonics Check-up of repercussions through commutation notches; Check-up of repercussions on audio-frequency centralized ripple control; Check-up of the short-circuit current according to Section Check-up of the dynamic network support according to Section Check-up of active power output and reactive power provision according to Sections and

45 Outlook In other countries like France, Spain and Greece, similar grid codes have been or will be released. ENTSO-E has proposed a European-wide grid code. It is highly controversial, but should apply in all European countries in about 2 years.

46 References Technical Regulations for the Interconnection of Wind Power Plants to the Power Systems, by Julija Matevosyan, Sigrid M. Bolik, Thomas Ackermann, Chapter 11, Wind Power in Power Systems, Wiley & Sons; German TransmissionCode 2007, ( > 60 kv), VDN, August _engl.pdf German Technical Guideline 2008: Generating Plants Connected to the Medium-Voltage Network, (1 kv 60 kv), BDEW, June 2008, 92F/$file/BDEW_RL_EA-am-MS-Netz_engl.pdf Generators connected to the low voltage distribution network Technical requirements for the connection to and parallel operation with lowvoltage distribution networks(<= 1kV), VDE. 46

47 Grid Codes and Technical Directives Various Grid Codes call for validated models: Germany: Technical Guideline Generating Plants Connected to the Medium- Voltage Network Chapter 6 Verification of the electrical properties, BDEW Technical Directive Part 4 Demands on Modeling and Validating Simulation Models of the Electrical Characteristics of Power Generating Units and Systems, FGW e.v. UK: The Grid Code, National Grid Electricity Transmission plc Spain: P12.3 Spanish Requirements for Wind Turbine Models, RED Electrica de España Denmark: Technical regulation for wind power plants with a power output greater than 11 kw Appendix 2: Simulation Models, Energinet.dk 47

48 Thanks you for your attention 48