Mitigation and analysis of sub synchronous resonance for DFIG based wind farm using STATCOM controller

Large-scale integration in transmission networks has led to several challenges; one of which is the need for increased transmission capacity to transport a bulk amount of power without affecting the voltage. In case of transmitting power to large distances series compensation is used along with Doubly-Fed Induction Generator (DFIG) wind turbine and it is simulated using MATLAB Simulink and the results obtained are validated. DFIG wind turbine is operated at normal operating state. Due to series compensation Sub Synchronous Resonance (SSR) occurs which is quite harmful to the wind generator because of the frequency variation, the gear mechanics of the generator gets damaged. When a larger disturbance occurred in any part of the study system at any bus bar, the effect of SSR would be more harmful. The effect of SSR depends on the compensation percentage we used for series compensation. SSR can be mitigated by using Flexible AC transmission System (FACTS) devices such as STATCOM, SVC, and SSSC. We use STATCOM because of its high stability margin, low switching loss and variable voltage rating. Whenever disturbance occurs in the transmission line then STATCOM comes into action by supplying reactive power and absorbing real power thus maintaining the system stability. The STATCOM controller gives pulse to the STATCOM for respective action such as real power absorption or reactive power injection. Thus the Wind turbine is protected and system stability is maintained.