汽轮机超速保护控制系统的性能优化及其对电网频率的影响分析

Optimization of Over-Speed Protection Controller for Steam Turbine and Its Influence on Frequency of Power Grid

现代化大型机组的超速保护控制系统(over-speed protection control,OPC)的控制策略如果不当,不仅起不到应有的超速保护作用,而且会造成汽门频繁启闭,产生"乒乓"现象。文章通过对OPC振荡机理的分析,得出系统振荡的根本原因是OPC的控制参数不合理及与其它保护措施不配合。利用OPC的动作特性图得出OPC的动作时限及阀门开度的数学表达式,针对2006年7月7日贵阳南部电网事故提出3种OPC的动作修改方案,并根据实际系统,用NETOMAC程序建立了原动机、调速器和汽轮发电机过速保护的详细模型,通过仿真证明了修改方案的正确性。并提出相应的改进建议。

At present over-speed protection controllers （OPC） are widely adopted in modern large turbo-generating units, however under inappropriate control strategy, not only OPC cannot play due over-speed protection role, but also it makes steam valves being frequently opened and closed. By means of analyzing oscillation mechanism of OPC, it is found that the basic reason causing system oscillation consists in unreasonable parameters of OPC and the mismatching of OPC with other protection measures. By use of performance chart of OPC, the mathematical expressions for actuation duration and valve opening of OPC are obtained. Taking the fault occurred on July 7, 2006 in South Guiyang power network for example, three modified schemes of OPC action are put forward, and according to actual system, detailed model for prime mover, governor and over-speed protection of turbo-generator unit are built by NETOMAC. Simulation results show that the modified schemes are correct, accordingly corresponding improving suggestions are proposed.