计及运行工况的MMC换流阀可靠性建模与分析

模块化多电平换流器(MMC)换流阀作为高压直流输电系统的核心设备,其可靠性关系到整个输电系统的安全稳定运行。以典型高压直流输电MMC换流阀为例,考虑换流阀运行工况,建立基于故障树分析方法的MMC换流阀的可靠性模型,并对其薄弱环节进行分析。首先,建立融入换流阀运行工况IGBT、二极管等元件的故障率模型;其次,考虑MMC换流阀功率模块和外围控制保护系统等,运用故障树分析方法,建立MMC换流阀故障树模型,得到相应可靠性指标的表达式;最后,根据可靠性指标公式计算各元件的故障率,采用概率灵敏度和关键灵敏度指标,辨识MMC换流阀的薄弱环节。结果表明:在整流和逆变工况下,MMC换流阀和元件的故障率最大,而在纯无功工况下故障率最小; IGBT模块和电源供给是MMC换流阀的薄弱环节,MMC子模块性能对换流阀可靠性的影响最为显著。

Reliability modeling and analysis of MMC converter valve considering operation conditions

As the core equipment of HVDC(High Voltage Direct Current) transmission system, the reliability of MMC(Modular Multilevel Converter) converter valve is related to the safe and stable operation of the whole transmission system. Considering the influence of working condition, the reliability model is established and the weak components are analyzed for the traditional HVDC transmission MMC converter valve based on the fault tree analysis method. Firstly, the failure rate models of IGBT and diode are established considering the influence of operating conditions. Then, the fault tree model of the MMC converter valve is established by the fault tree analysis method, and the corresponding reliability index formulas are obtained considering the power module and peripheral control protection system. Finally, the failure rate of each component is calculated according to the reliability index formula, and the weak components of the MMC converter valve are identified based on the probability sensitivity and the critical sensitivity indexes. The results show that the failure rate of the MMC converter valve and component is biggest under the conditions of rectifier and inverter, and the failure rate is smallest under pure reactive power condition, the IGBT module and the power supply are the weak components of the MMC valve, and the performance of the MMC sub module has the most significant influence on the reliability of the valve.