Integrating Large Supplies of Wind Power - System Performance and Maintaining Quality of Supply in the Transmission Network

Transcription

1 Grid Planning Dr. Winter Integrating Large Supplies of Wind Power - System Performance and Maintaining Quality of Supply in the Transmission Network ETG Conference Reliability of Power Supply on 5 February 2003 in Mannheim

2 Installed wind power capacity in Europe Total: 18,578 MW (As per July 2002) Others 2.2% 407 MW Sweden 1.5% 280 MW Ireland 0.7% 125 MW Portugal 0.7% 127 MW Greece 1.5% 272 MW Great Britain 2.7% 498 MW Netherlands 2.7% 501 MW Italy 3.8% 700 MW Denmark 13.2% 2,456 MW Spain 19.9% 3,712 MW Quelle: Windpower Monthly Germany 51.1% 9,500 MW ETG Conference Reliability of Power Supply 5 February 2003 Page 2

3 Installed Capacity in MW Development of Wind Power in Germany 50,000 45,000 40,000 35,000 Onshore and Offshore 30,000 25,000 20,000 15,000 10,000 Onshore Onshore in the E.ON Netz control area 5, Year ETG Conference Reliability of Power Supply 5 February 2003 Page 3

4 System engineering criteria for limiting wind power supply Thermal limits Voltage stability Frequency stability ETG Conference Reliability of Power Supply 5 February 2003 Page 4

5 Thermal limits Structurally weak regions in the north of the control area Setting up of new routes ETG Conference Reliability of Power Supply 5 February 2003 Page 5

6 Thermal limits Grid upgrading and grid connection requirements Wind power development + grid upgrading for E.ON Netz MW 18,000 14,000 10,000 Installed wind capacity Additional route kilometres ,000 Accumulated additional route kilometres 110 and 380 kv in km 1, , , Cost 110 million 400 million 550 million Source: IAEW RWTH Aachen 2002 ETG Conference Reliability of Power Supply 5 February 2003 Page 6

7 Capacity MW System control / Frequency stability Wind power supply in the E.ON Netz control area Mon Tue Wed Thu Fri Sat Sun 2,400 MW active power decrease in 24 hours Weekly rate from ETG Conference Reliability of Power Supply 5 February 2003 Page 7

8 MW 18,000 14,000 2,300 4,200 Frequency stability 8,000 System control requirements Forecast wind development and average control requirement for E.ON Netz 10,000 Installed wind capacity Controlling power range needed 10,000 6,000 2, Source: IAEW RWTH Aachen 2002 ETG Conference Reliability of Power Supply 5 February 2003 Page 8

9 Frequency stability Voltage profile after a three-phase fault as per 2002 Failure of the entire WEC supply ETG Conference Reliability of Power Supply 5 February 2003 Page 9

10 Frequency stability Voltage levels when a wind farm is integrated into the 110 kv grid 110 kv 20 kv 0.69 kv S1 S2 ASG 3~ As per December 2002: When the terminal voltage is 80% of the nominal system voltage, the wind energy converters are disconnected from the grid for an indefinite period. ETG Conference Reliability of Power Supply 5 February 2003 Page 10

11 Frequency stability System voltage waveshape during and after system faults U N [pu] 1,1 1,0 0,9 0,8 0,7 0,6 0, t/s System voltage at the connecting point (110 kv) System voltage on the main bus bar in the wind farm (20 kv) System voltage at the wind generator (0.7 kv) System voltage at the wind generator (0.7 kv), voltage control ETG Conference Reliability of Power Supply 5 February 2003 Page 11

12 Frequency stability Failure of wind power supply after a three-phase fault in the 380 kv grid near Dollern substation Wind distribution in the E.ON Netz control area in Dec Hanover area Ems-Elbe Weser-Ems Schleswig-Holstein 850 MW 500 MW 1,350 MW 2,300 MW Scenario 2001 Scenario Dec Scenario Dec Observation point Failure capacity Inst. wind capacity System connecting point Generator terminals Machine terminals 2,700 MW 2,880 MW < 3,000 MW 3,000 MW 5,000 MW New connecting regulations for WECs in force as of ,500 MW ETG Conference Reliability of Power Supply 5 February 2003 Page 12

13 Frequency stability Action taken in the event of a fault in order to reduce the area affected and the power loss No automatic disconnection of wind farms above the red characteristic curve Aim: reduction of the area affected by the failure and the loss of wind power when a fault occurs (< 3,000 MW) ETG Conference Reliability of Power Supply 5 February 2003 Page 13

14 Voltage stability ASG 3~ Wind energy converter (WEC) with an asynchronous generator High-speed asynchronous generator Gearbox Reactive-power compensation by means of condensers Non-variable rotor speed Reactive power only adjustable in steps No voltage control / cos phi control Short-term reactions after fault rectification SG 3~ WEC with synchronous generator Low-speed synchronous generator with a large number of pole pairs No gearbox Variable rotor speed Pulse-controlled inverter (var. P/Q) Voltage control / cos phi control No reactions ASG 3~ WEC with double-fed induction generator High-speed asynchronous generator Gearbox Variable rotor speed Fully adjustable reactive power Voltage control / cos phi control Reactions after fault rectification lasting more than 15 seconds Reactions when control is switched on after system faults ETG Conference Reliability of Power Supply 5 February 2003 Page 14

15 Voltage stability Induction generator WEC performance during a system fault U/Un L1 L2 L3 I/[MVA] L1 L2 L3 P/[MW] Q/[Mvar] n [1/min] t [sec] 1.00 ETG Conference Reliability of Power Supply 5 February 2003 Page 15

16 Voltage stability DFIG WEC performance during a system fault U/Un L1 L2 L3 I [MVA] L1 L2 L3 P/[MW] Q/[Mvar] Control OFF t [sec] ETG Conference Reliability of Power Supply 5 February 2003 Page 16

17 Voltage stability UCTE/CENTREL model - installed wind capacity: 5,000 MW System voltages after a 3-phase fault at Dollern substation fault remedied after 150 ms Unterweser 380 kv Deviation of the system voltage from the nominal system voltage in % -50% Krümmel 380 kv -50% Conneforde 220 kv -50% Sottrum Ems Elbe 110 kv Oldenburg Weser Ems 110 kv -50% -50% Hamburg Nord Schleswig-Holstein 110 kv -50% t [sec] Voltage dip caused by the phase effects of wind farms, control of which ceases in the event of a fault brought about by high rotor currents (around 75% of rated voltage) ETG Conference Reliability of Power Supply 5 February 2003 Page 17

18 Voltage stability Fault occurs Fault rectified Disconnection of wind farms incompatible with the system t [msec] Trip of the under-voltage protection Time to disconnection of the wind farm t [msec] 100% 90% 80% 70% 60% 50% t [sec] No selective disconnection of wind farms incompatible with the system Selective disconnection of wind farms incompatible with the system Wind farms switch from cos control to voltage control during system faults ETG Conference Reliability of Power Supply 5 February 2003 Page 18

19 Requirements of the dynamic performance of wind energy converters in the transmission network Switch from cos control to voltage control in the event of voltage dips greater than 10 % Reactive power intake may only exceed 25% of the nominal reactive power of the wind farm during transient balancing time (about 400 ms) Or optionally Selective cut-off of wind generators incompatible with the system - Synchronisation within 2 seconds of the fault being rectified - Increase in power with a gradient of 10% rated power per second - The failure of a wind farm must not last longer than 12 seconds ETG Conference Reliability of Power Supply 5 February 2003 Page 19

20 Failure of wind energy converters during a 3-phase system fault at Dollern substation long-term failure Grid connection regulations for WECs up to 31 December 2002: Complete cut-off of all generators if the generator terminal voltage drops below Observation point 80% of nominal voltage. F [Hz] Scenario 2002 Generator terminals Power loss 2,880 MW 50 Hz 49.8 Hz 49.6 Hz 49.4 Hz 49.2 Hz 49.0 Hz 5000 P [MW] t[sec] ETG Conference Reliability of Power Supply 5 February 2003 Page 20

21 WEC failures during a 3-phase system fault at Dollern substation short-term loss of 3,000 MW Change in WEC performance through re-powering including generators that are already connected F [Hz] Scenario 2005 Observation point Generator terminals Power loss 3,000 MW 50 Hz 49.8 Hz 49.6 Hz 49.4 Hz 49.2 Hz 49.0 Hz 5000 P [MW] t[sec] ETG Conference Reliability of Power Supply 5 February 2003 Page 21

22 Summary There will be further growth in onshore and offshore wind power Integration of wind power requires a restructuring of the transmission networks plus additional extensive power station reserve capacity No exceeding of the technical limits of the overall system (optimisation of the overall system performance) A joint, coordinated approach involving project planners, producers of wind energy converters and systems technology, network operators, licensing authorities and/or politicians is required Additional burdens on the network operators must be fairly distributed (nationwide and throughout Europe) and not shouldered by individual companies ETG Conference Reliability of Power Supply 5 February 2003 Page 22