基于负序电流补偿的并联风电变流器故障容错控制

海上风电运行环境恶劣,风电功率随机波动性大,导致功率器件极易发生故障.故障容错控制是提高风电并联变流器运行可靠性以及功率可用度的有效手段.并联风电变流器某相发生开路故障后,对并联风电变流器的故障运行机理进行了详细分析.在此基础上,提出一种基于负序电流补偿的并网风电变流器故障容错控制,利用非故障变流器模块对故障变流器模块进行负序电流补偿.当系统功率小于或等于0.5 p.u.时,在保证并网侧电流平衡的条件下实现变流器最大输出功率;当系统功率大于0.5 p.u.时,首先满足系统有功输出要求,然后对负序电流进行补偿.最后通过仿真验证了该控制理论的正确性与可行性.

Fault-tolerant control based on negative-sequence current compensation for parallel wind power converters

The operating environment of offshore wind power is harsh, and the random fluctuation of wind power is large, which leads the power devices easily to fail. Fault-tolerant control is an effective means to improve the reliability and availability of parallel wind power converters. The fault operation mechanism of a parallel wind power converter in detail is analyzed after open circuit fault occurs in a phase of parallel wind power converter. On this basis, a fault-tolerant control based on negative-sequence current compensation for parallel wind power converters 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 p. u.,the maximum output power of the converter is realized under the condition of ensuring the current balance at the grid-connected side; when the system power is greater than 0.5 p. u.,the negative-sequence current is compensated when the maximum output power is satisfied of the first importance. Finally, the correctness and feasibility of the control theory are verified by simulation.