Low cost current source converter solutions for variable speed wind energy conversion systems

The voltage-boost characteristic of the pulse-width-modulated (PWM) current-source inverter (CSI) is in accordance with the nature of a variable-speed wind energy conversion system (WECS). In view of this, low-cost power converter solutions using diode/thyristor rectifier with PWM CSI are proposed and investigated in this paper for wind power generation applications. Detailed steady-state analysis of the diode rectifier interfacing a permanent magnet synchronous generator is conducted. The results and the grid-side requirements are then collectively used to evaluate the operating range of the whole system. Comparison with the combination of diode rectifier and PWM voltage-source inverter (VSI) reveals the advantages of the PWM CSI based solutions. Additionally, it is further illustrated that a thyristor rectifier can provide extended operating ranges than a diode rectifier in a PWM CSI based solution. Simulation results on a medium-voltage system are provided to verify the theoretical analysis and proposed solutions.