HELSINKI UNIVERSITY OF TECHNOLOGY Department of Electrical and

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HELSINKI UNIVERSITY OF TECHNOLOGY Department of Electrical and Communications Engineering Analysis of a 1.

HELSINKI UNIVERSITY OF TECHNOLOGY Department of Electrical and Communications Engineering Analysis of a 1. 7 MVA Doubly Fed Wind-Power Induction Generator during Power Systems Disturbances Slavomir Seman, Sami Kanerva, Antero Arkkio Laboratory of Electromechanics Helsinki University of Technology Jouko Niiranen ABB Oy, Finland

Overview • Introduction • The Doubly Fed Induction Generator • Frequency Converter and Control

Overview • Introduction • The Doubly Fed Induction Generator • Frequency Converter and Control • Crowbar • Modeling of The Network, Transformer and Transmission Line • Simulation Results • Conclusions

The Doubly Fed Induction Generator Transient Model of the Generator • The machine equations

The Doubly Fed Induction Generator Transient Model of the Generator • The machine equations x-y reference frame fixed with rotor • Constant speed - no equation of movement included P U 1. 7 MW N N, stator U (L-L) 690 V (delta) max, rotor n f N N, stator 2472 V (star) 1500 rpm 50 Hz

Frequency Converter and Control Model of the Frequency Converter • Two back-to-back connected voltage

Frequency Converter and Control Model of the Frequency Converter • Two back-to-back connected voltage source inverters (VSI) • DTC • The Network Side Converter - simplification 1 -st order filter transfer function • PI controller Udc -level

The Rotor Side Converter Model of the Rotor Side Converter • Modified DTC •

The Rotor Side Converter Model of the Rotor Side Converter • Modified DTC • Input demanded PF or Q , Tref • Voltage vector applied - optimal switching table • The tangential component of the voltage vector controls the torque whereas the radial component increases or decreases the flux magnitude

Over-Current Protection - Crowbar Passive Crowbar • over-current protection - the rotor, rotor side

Over-Current Protection - Crowbar Passive Crowbar • over-current protection - the rotor, rotor side converter • no chopper mode • disconnection of the converter rotor is connected to CB • CB is active until MCB disconnects stator from the network

Modeling of the Network, Transformer and Transmission Line Modelling of test set-up • Power

Modeling of the Network, Transformer and Transmission Line Modelling of test set-up • Power supply - SG or 3 phase V source with short circuit reactance and inductance • Transmission line - R-L equivalent circuit • Transformer - short circuit R-L and stray C, no saturation • Short circuiting TR - R-L equivalent circuit

Simulation Results - Voltage Dip without Crowbar Matlab-Simulink, t_step = 0. 5 e-7, T_ref

Simulation Results - Voltage Dip without Crowbar Matlab-Simulink, t_step = 0. 5 e-7, T_ref =0. 5 p. u. , w_ref = 1. 067 p. u. , Voltage dip 35% Un Voltage dip applied MCB open

Simulation Results - Voltage Dip without Crowbar Voltage dip applied MCB open

Simulation Results - Voltage Dip without Crowbar Voltage dip applied MCB open

Simulation Results - Voltage Dip with Passive Crowbar Matlab-Simulink, t_step = 0. 5 e-7,

Simulation Results - Voltage Dip with Passive Crowbar Matlab-Simulink, t_step = 0. 5 e-7, T_ref =0. 5 p. u. , w_ref = 1. 067 p. u. , Voltage dip 35% Un Voltage dip applied MCB open

Simulation Results - Voltage Dip with Passive Crowbar Voltage dip applied MCB open

Simulation Results - Voltage Dip with Passive Crowbar Voltage dip applied MCB open

Conclusions • Transient behaviour of DTC controlled DFIG for wind-power applications studied. • The

Conclusions • Transient behaviour of DTC controlled DFIG for wind-power applications studied. • The transient simulation results with and without crowbar were compared. • When the crowbar is implemented, the stator and rotor transient current decay rapidly and rotor circuit is properly protected. • Transient electromagnetic torque is reduced by means of crowbar but oscillates longer than in case without crowbar.