基于多相风力发电系统的容错控制策略研究

多相电机具有转矩大、转矩脉动低以及容错性高的特点，尤为适用于风力发电系统这种低速大功率的应用场合。提出一种基于多相直驱永磁同步发电机的风力发电系统，多相风机经三相桥式不控整流器、隔离型DC/DC和模块化多电平变流器并入高压直流电网。首先，采用基于转速外环的MPPT控制得到三相桥式不控整流器的平均电流参考值；然后，根据变流器工作状态对各套三相桥式不控整流器的电流参考值进行重构，实现正常相输出功率平衡，确保故障相不会出现过流，达到系统的容错控制，提高可靠性；最后，通过模块化多电平变流器单桥臂接入直流电网，降低了变流器复杂度。以18相风力发电机为例，搭建了Matlab/Simulink仿真模型，验证了所提拓扑结构及容错控制策略的有效性。

Fault-Tolerant Control Strategy Based on Multi-Phase Wind Power System

Owing to their characteristics of large torque, low torque ripple, and high fault tolerance, multi-phase motors are especially suitable for low-speed high-power application scenarios such as wind power systems. This paper proposes a wind power system based on multi-phase direct-drive permanent magnet synchronous generators. The multi-phase wind turbines are integrated into the high-voltage direct-current (DC) grid via three-phase bridge uncontrolled rectifiers, isolated DC/DC converters, and modular multilevel converters (MMCs). Specifically, an average current reference value of the three-phase bridge uncontrolled rectifiers is obtained by maximum power point tracking (MPPT) control based on an outer speed loop. Then, the current reference values of each set of three-phase bridge uncontrolled rectifiers are reconstructed according to the working state of the converter for the output power balance of the normal phase. The aim is to ensure that overcurrent does not occur in the fault phase, achieve fault-tolerant control of the system, and thereby improve reliability. Finally, the wind turbine is connected to the DC grid via the single bridge arm of the MMC to reduce the complexity of the converter. With 18-phase wind turbines as an example, a Matlab/Simulink simulation model is built to verify the effectiveness of the proposed topology and fault-tolerant control strategy.