October 25 Netzkurzschlussverhalten von umrichterbetriebenen regenerativen Energieerzeugern und -speichern Dr. Georg Möhlenkamp 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP
Overview ALSTOM Power Conversion GmbH Key Problem: new Grid Connection Regulations Problem definition for the wind turbines Characteristics of the wind converters and adaptations for new Grid Codes Fixed speed asynchronous generator (ASG) Variable speed synchronous generator (SG) Variable speed doubly fed ASG (DASG) Conclusion 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 2
Power Conversion International Power Conversion a business in ALSTOM Industry equipment Motors & Generators Marine & Offshore Customised technology for customer excellence 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 3
International organisation UNITED KINGDOM Rugby Kidsgrove Glasgow FRANCE Massy Nancy GERMANY Berlin USA Pittsburgh CHINA Beijing & Wuhan BRASILIEN Belo Horizonte NEW India Chennai NEW China Shanghai 35 Employees in 7 countries 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 4
General Drives Wind Energy Leading supplier of generator and variable speed drive systems for wind turbines Common design studies Selection of optimised drive solutions Manufacturing of prototypes and joint evaluation of system tests Present in several committees, e. g. FGW, VDN 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 5
Key Problem The effect of wind power cannot be neglected anymore Grid operators expect wind turbines to behave like conventional synchronous generator: no switch-off during voltage dips high short circuit current voltage buffering through reactive current during voltage dips fast recovery of active power New grid codes for wind turbines 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 6
Key Problem definition for the wind turbines resulting from the grid connection requirements 1. Extended frequency range: 47.5 Hz - [49 Hz - 51 Hz -] 51.5 Hz 2. Extended voltage range: 8 % - [9 % -] 11 % (for permanent operation) 3. Power factor can be chosen from 1 % active to 1 % reactive current to match the demanded reactive power at the grid connection point [cos ϕ =,95 at low voltage side] 4. Ride through of voltage dips down to 15 % U N [Disconnection at 8 % U N ] U/U N [ % ] 1 15 3. t/ms 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 7
Fixed speed turbines: ASG Directly coupled asynchronous generator Stall control Compensation of reactive power by capacitors Robust, cost efficient High short circuit current Turbine Transformer ASG High voltage High voltage 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 8
Solution for ASG Point 1 Voltage Point 2 Frequency No problem in the required range! Point 3 Reactive Power Not possible with capacitors! Point 4 Voltage dip Ride through of voltage dips possible! 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 9
Point 3: Reactive Power Capacitors cannot meet the required reactive current characteristics ALSTOM Power Conditioning System (PCS) provides reactive current Reactice current (IB /IN) [%] 1 8 6 4 2 1 2 3 4 5 6 7 8 9 1 Voltage dip [%] Contrary to connventional capacitor can the selfcommutated converter follow the desired value Requirement Conv. capacitor 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 1
Simulation: ASG with PCS u Grid / u N 1.5 5 i Grid / i N -5 4 2 P / P N Q / P N -2-4 2 M / M N -2-4 -.5.5.1.15.2.25.3.35.4.45 t [s] Voltage dip down to 2 % U N 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 11
Fixed speed wind turbine with PCS MV-power system (e.g. 2-kV) G ~ WT-1 HV grid (ge.g. 11-kV) PCS-1 Decentral G ~ WT-2 PCS-2 Decentral G ~ WT-n PCS-n Decentral 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 12
Variable speed turbine: SG Fully fed synchronous generator Generator decoupled from grid via the converter Pitch control Reactive power provided by converter Limited short circuit current (1.5 I N ) Turbine High voltage High voltage Transformer ~ ~ SG 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 13
5 MW Drive System MULTIBRID Wind Energy Converter High power density due to optimised gearbox- and generator concept Medium voltage converter and transformer in offshorecontainer Permanent magnets synchronous generator 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 14
5 MW Drive System Overview Grid connected Switchgear in Tower Transformer-Container Converter-Container Sea cable 2 kv 16 kva,4 kv UPS 3 5 Hz 2 kv I > I >> V <> f <> M 5,3 MVA V R = 3, kv G M M 2 kv 6 MVA 3, kv 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 15
Solution for SG Point 1 Voltage Point 2 Frequency Solved by new system management and software adaptations! Point 3 Reactive Power Converter rating has to be increased for higher reactive power! Point 4 Voltage dip Minor Hardware adaptation but no influence on the grid characteristic! 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 16
Simulation: SG 1 u Grid / u N.5 2 1 i Grid / i N -1-2 1 P / P N Q / P N -1-2 -.5.5.1.15.2.25.3.35.4.45 t [s] Voltage dip down to 2 % U N 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 17
Variabe speed turbine: DASG Doubly fed asynchronous generator Most common wind turbine design Reactive power provided by generator and converter High short circuit current Transformer DASG High voltage High voltage ~ ~ 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 18
Solution for DASG (ProWind) 1 Frequency Point 2 Voltage 3 Reactive power Solved by new system management and software adaptations! Point 4 Voltage dip Hardware adaptations necessary! 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 19
Point 4: Voltage dip Problem Voltage jumps lead to over currents like short circuit currents Converter cannot handle the over current Save operation is guarantied by protective devices, e. g. circuit breaker, rotor crowbar Up to now: Safety shut-down New: Continuous operation and several voltage steps in short time 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 2
Point 4: Voltage dip Solution No principle modification of the safety devices Reinforcement of involved parts and fast sequence control Lowest possible mechanical stress Hardware option Retrofit possible Point 4 Voltage dip: 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 21
Characteristics: DASG Voltage dip without triggering of the Rotor Crowbar (RC): controlled operation, low mechanical stress Triggering of the Rotor Crowbar: Ride through with maximum grid current and fastest possible return to normal operation after the voltage recovery Option: Disconnection of the stator and resynchronisation: reduced grid current, low mechanical stress at voltage recovery RC 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 22
Simulation: DASG, without stator disconnection u grid / u N i grid / i N 1.5 4 2-2 -4 P / P N Q / P N 2-2 M / M N 2-2 -4.1.2.3.4.5 t [s] Voltage dip down to 2 % U N 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 23
Simulation: DASG, with stator disconnection u Grid / u N i Grid / i N 1.5 4 2-2 -4.5 P / P N Q / P N -.5 M / M N -1-1.5 1-1 -2-3 -4.5 1 1.5 t [s] Voltage dip down to 2 % U N 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 24
Conclusion All types of wind turbine generator / converter concepts can comply with the new grid codes All have different advantages / drawbacks regarding short circuit current / reactive power / active power The characteristics during grid faults can be influenced by the system management, e. g. stator disconnection 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 25
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Wind Test Bench Transformer Voltage change over Converter Generator 1,5 MW Drive 1,5 MW 1 kv M ~ ~ 1,6 MVA 69 V +3 % Tapping in 7 V steps 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 27
Simulation model (VDN) Transformer HV - MV Transformer MV - LV ~ = Pro Wind = ~ Z G i Grid 11 % u k 6 % u k Generator u Grid ~ Z F u PCC u Gen M Turbine n Crowbar 1.25 APCG / 5MOP8_EN-(Netzkurzschlussverhalten-Energieerzeuger).PPT / Dr.MÖHLENKAMP 28