基于电压和电流特征的双馈风电变流器功率器件开路故障综合诊断

Comprehensive Diagnosis of Open-Circuit Fault for Power Devices of Doubly-Fed Wind Power Converter Based on the Features of Voltage and Current

变流器功率器件开路故障监测与识别对提高双馈风电系统智能运维至关重要。针对现有基于变流器电压或电流单一特征以及固定阈值的方法难以同时实现功率器件故障诊断监测与识别问题,该文提出一种基于变流器直流母线电压的故障监测与基于转子电流故障识别的综合诊断方法。首先,理论分析变流器功率器件开路故障对直流母线电压的影响,基于累积和(CUSUM)算法,提出基于直流母线电压特征的故障监测方法;其次,针对转子输出电流非平稳特性和阈值固定问题,提出基于归一化输出电流平均值和绝对平均值为故障特征量及自适应阈值的故障识别方法;最后,仿真模拟不同功率器件先后开路,验证所提方法的有效性,以风速随机及电网电压跌落为场景验证所提方法的鲁棒性。同时,以功率器件典型开路故障实验数据验证仿真分析的准确性。仿真与实验结果表明,所提方法能准确实现变流器功率器件开路故障诊断。

Open-circuit fault monitoring and identification for power converter devices are of the utmost importance for improving the intelligence operations for doubly-fed wind power system.Aiming at the problems that the existing diagnosis methods are difficult to achieve fault monitoring and identification simultaneously for power devices based on the converter voltage or current single feature and fixed threshold,a comprehensive diagnosis method of fault monitoring based on converter DC-bus voltage and fault identification based on the rotor current is proposed.First of all,theoretical analysis of the influence of power device failure of the converter on the DC-bus voltage.According to the cumulative sum(CUSUM)algorithm,an open-circuit fault monitoring method of power devices based on the feature of DC-bus voltage is put forward.Secondly,in view of the non-stationary characteristic and fixed threshold of the rotor current,a fault identification method based on the normalized output current average value and absolute average value as the fault feature and adaptive threshold is presented.Finally,to verify the effectiveness of the proposed method with the different power devices open-circuit faults simulation,and the robustness is validated by the scenes of stochastic wind and grid voltage drop.At the same time,the accuracy of the simulation analysis is verified by testing the typical open-circuit fault of the power device.The simulation and experimental results show that,the proposed method could accurately realize the comprehensive diagnosis of the power converter devices open-circuit fault.