A new DPC method for single VSC based DFIG under unbalanced grid voltage condition

Abstract

This paper proposes a new Direct Power Control (DPC) strategy for a single Voltage Source Converter (VSC) based Doubly Fed Induction Generator (DFIG) by employing Four Switch Three Phase Inverter (FSTPI) instead of Six Switch Three Phase Inverter (SSTPI). Reduce number of active switch not only improves reliability but also decreases cost, and conduction losses. The new switching table for FSTPI is based on principle of similarity between FSTPI and SSTPI i.e. by using a technique the four unbalanced voltage vectors which generated by FSTPI will be converted to six balanced voltage vectors. In addition, the behavior of the DFIG under unbalanced grid voltage is investigated and then alternative DFIG control targets, such as reducing stator current unbalance, torque, and power pulsation minimization, are identified. Simulation results using Matlab/Simulink are presented for a 1-MW DFIG Wind generation system to validate the proposed control scheme.