基于实测数据的同相供电装置变流器

基于实测数据的同相供电装置变流器

可靠性评估

RELIABILITY EVALUATION OF CONVERTER OF IN-PHASE POWER SUPPLY DEVICE BASED ON MEASURED DATA

2020年05月

摘要

电气化铁路供电采用单相交流制，存在电分相问题和以负序为主的电能质量问题，阻碍了电气化铁路的长远发展。采用对称补偿原理的同相供电技术能够较好解决上述问题。同相供电装置的核心部件为同相补偿变流器，为保证同相供电系统的安全稳定需要对其进行可靠性评估，并研究提高可靠性措施。

首先评估主要元件可靠性。考虑运行过程中牵引负荷是实时波动的，基于物理失效机理，结合功率损耗计算模型、热网络模型、结温计算方法计算出IGBT模块结温，使用雨流算法处理得到多个热循环及对应的结温波动值、平均结温值，综合利用器件寿命失效模型和线性疲劳老化失效模型得出IGBT模块各元件的失效率。对串联电抗器、直流电容器、控制底板，使用可靠性预计手册给出的数据计算相应失效率。从而完成了变流器各组成元件可靠性模型。

然后，针对同相补偿变流器多模块级联结构，考虑功率元件的失效率会受到级联功率模块数的投入或退出的影响，建立k/n(G)模型对其可靠性进行动态分析。对沙峪牵引变电所运用同相补偿变流器进行分析，结合牵引负荷数据，评估了其可靠性。

最后，对变流器参数和负荷特性进行研究，分析了影响同相补偿变流器可靠性的因素，包括功率因数、开关频率等。提出了变频控制方法，设定适当步长，选取合适的切换电流点和切换频率，使得同相补偿变流器的失效率得以有效降低，可靠性得以提高。结合实测负荷数据验证了变频控制方法的可行性。

关键词：同相补偿变流器；可靠性分析；结温；变频控制

Abstract

The single-phase AC system is used for power supply of electrified railways, the problems of electric phase separation and power quality with a negative sequence are the main obstacles to the long-term development of electrified railways. The above problems can be solved by in-phase power supply technology using symmetric compensation principle. The core component of the in-phase power supply device is the in-phase compensation converter. To ensure the safety and stability of the in-phase power supply system, it is necessary to evaluate its reliability and study measures to improve reliability.

First, the reliability of the main components needs to be evaluated. Considering that the traction load fluctuates in real time during operation, based on the physical failure mechanism, combined with the power loss calculation model, thermal network model, and junction temperature calculation method, the junction temperature of IGBT module can be calculated. Multiple thermal cycles, corresponding junction temperature fluctuations and average junction temperature can be obtained by the rain flow algorithm, and the failure rate of each element of the IGBT module is obtained using the device life failure model and the linear fatigue aging failure model. For series reactors, DC capacitors, and control boards, the failure rate is calculated using the data given in the reliability prediction manual. Thus, the reliability model of each component of the converter is completed.

Then, a k/n(G) model is established to dynamically analyze its reliability because of the multi-module cascade structure of the in-phase compensation converter. The failure rate of power components will be affected by the input or withdrawal of cascaded power modules. The in-phase compensation converter of Shayu Traction Substation is analyzed, and its reliability is evaluated based on the traction load data.

Finally, the parameters and load characteristics of the converter are studied. The factors affecting the reliability of the in-phase compensation converter are analyzed, including power factor and switching frequency. A variable frequency control method is proposed, setting an appropriate step size, selecting an appropriate switching current point and switching frequency, so that the failure rate of the in-phase compensation converter can be effectively