Optimal Fault-tolerant Control for Improving the Availability of Parallel Wind Power Converters

The operating environment of offshore wind power is harsh, and the random fluctuation of wind power is large, which makes power devices easy to fail. Fault tolerant control is an effective means to improve the reliability and availability of wind power converters. Taking an open circuit fault of a parallel converter as an example, this paper analyzes the fault operation mechanism of a parallel wind power converter in detail. On this basis, a fault-tolerant control strategy based on negative-sequence current compensation is proposed, and a non-faulty converter module is used to compensate the negative-sequence current of the faulty converter module. When the system power is less than or equal to 0.5 pu, the maximum output power of the converter is realized under the condition of ensuring the current balance of the grid-connected side; when the system power is greater than 0.5pu, the negative sequence of the grid-side is controlled to minimum under the condition of outputting the maximum power. Finally, the correctness and feasibility of the control strategy theory are verified by simulation.