Cost-effective high-reliable power conditioner for grid-integration of multiple off-shore wind turbines connected in series

In the off-shore wind farm, improving the reliability of the power conversion system is totally necessary. Therefore, the grid-integration of multiple off-shore wind power generators connected in series using a three-phase current source PWM inverter is proposed. The power circuit of the proposed topology consists of permanent magnet synchronous generators, 12 pulse diode rectifiers and a current-source PWM inverter. A simple two-dimensional finite-time settling control scheme has been proposed and implemented to achieve the time-optimum response of the grid-connected current source PWM inverter with an LC filter. The time optimum response with the settling time of two sampling periods is derived actually in the lab. From the measurements, sudden changes in the DC-link current will cause the interconnected power system instability especially for weak grid and for assuring the stability of the proposed grid integration system, the change rate of the DC current should be reduced. The experimental results verify the effectiveness of the proposed control method, designed for the current-source type inverter.