Coordination of A Three Level STATCOM and Enhanced Field Oriented Controller for Grid Connected DFIG to Improve Performance during Different Faults

Abstract

With increase in electric power demand, raise in oil prices, transmission lines were forced to operate near to its full load and due to the drastic change in weather conditions, thermal limit is increasing and the system is operating with less security margin. To meet increased power demand, DFIG based wind generation system is a better alternative. For improving power flow capability and to increase security STATCOM can be adopted. As per modern grid rules, DFIG needs to operate without losing synchronism called Low Voltage Ride Through (LVRT) during severe grid faults. Hence for this, enhanced field oriented control technique (EFOC) was adopted in Rotor Side Control (RSC) of DFIG converter to improve power flow transfer and to improve dynamic and transient stability. The paper has an objective to damp pulsations in electromagnetic oscillations, improve voltage mitigation and limit surge currents and to enhance the operation of DFIG during symmetrical and asymmetrical faults. A three level STATCOM is coordinated to the system for obtaining much better stability and enhanced operation during grid fault. The STATCOM DC capacitor bank and DFIG converters are connected to a common DC point has advantages like improved real and reactive power flow control in STATCOM, better reactive power support from RSC and GSC with nearly constant DC link voltage maintenance and faster dynamic and transient operation during severe grid faults. For EFOC technique, rotor flux reference changes i