计及疲劳累积及健康状态的风电变流器可靠性评估模型

Reliability Evaluation Model of Wind Power Converter Considering Fatigue Accumulation and Health Status

双馈风机系统以其成熟性、稳定性和经济性在风力发电系统占据着主流地位。实际运行过程中,由随机风速和运行工况改变而引起的交变热应力,使得风电变流器可靠性逐渐降低。现有的风电变流器可靠性评估模型,大都只考虑大载荷作用或采用Miner线性疲劳累积模型,而忽略了变流器实际运行过程中小载荷作用以及健康状态对模块剩余寿命的影响。综合考虑这两种因素,采用分段式疲劳累积模型建立变流器可靠性评估模型,并设计功率循环试验对模型进行验证。同时在实际风速下对1.5MW双馈风电变流器进行算例分析,在不同健康状态下对比了开关频率、环境温度变化对双馈风电变流器可靠性的影响。结果表明,开关频率和环境温度对变流器可靠性影响较大,风电变流器故障率随着功率器件的老化显著升高。

Owing to its maturity,stability and economy,doubly-fed induction generator(DFIG)is dominant in wind power generation system.In the actual operation process,the alternating thermal stress caused by random wind speed and changes in operating condition makes the reliability of the wind power converter gradually decrease.Most of the reliability evaluation models of wind power converter only consider the large load action or adopt the Miner linear fatigue cumulative model,while ignoring the influence of the small load and the health status on module remaining life.In this paper,the two factors are considered,and the two-stage fatigue accumulative model is used to establish the reliability evaluation model of converter.The power cycle test is designed to validate this model.At the same time,a 1.5MW doubly-fed wind power converter is analyzed under the actual wind speed,and the influence of the switching frequency and environment temperature on the reliability of doubly-fed wind power converter is compared under different health conditions.The results show that the switching frequency and the ambient temperature have great effects on the reliability of the converter,and the failure rate of the wind power converter rises significantly with the aging of the power device.