基于传输线解耦法的MMC交直流系统多速率仿真

MMC AC/DC system′s multi⁃rate simulation based on transmission line decoupling method

MMC系统中含有大量开关器件,为及时检测到控制脉冲的跳变和防止出现数值震荡造成仿真不收敛的问题,需设置较小的仿真步长,但交直流系统小步长仿真将严重制约电磁暂态仿真速度。考虑到交流系统响应慢,可采用较大的步长仿真,因此该文采用基于传输线解耦法的多速率算法对MMC交直流系统进行电磁暂态仿真。根据各仿真步长和传输线延时之间的大小关系,分情况介绍多速率算法的实现和交互数据的处理,并通过加入延时解决大仿真步长大于线路传输延时的2倍情况下的耦合问题。最后搭建双端MMC交直流系统模型,对不同工况下多速率仿真的误差进行分析,验证基于传输线解耦法的多速率仿真算法可用于MMC交直流系统实时仿真平台的构建。

There are a large number of switching devices in MMC.In order to detect the jump of control pulse in time and prevent the problem of simulation′s non⁃convergence caused by the numerical oscillation,a smaller simulation step size need to be set.The speed of electromagnetic transient simulation will be severely restricted by small step size simulation of the AC/DC system.In consideration of the slow response of AC system,the larger step size simulation can be applied.Therefore,the multi⁃rate algorithm based on transmission line decoupling method is used to conduct the electromagnetic transient simulation of AC/DC system.According to the relationship between each simulation step size and transmission line time delay,the implementation of multi⁃rate algorithm and the processing of interactive data are introduced in detail,and the coupling problem occurring while the large simulation step size is larger than twice of the transmission delay is solved by adding time delay.A two⁃terminal MMC AC/DC system model is built to analyze the error of multi⁃rate simulation under the different working conditions.It is verified that the multi⁃rate simulation algorithm based on transmission line decoupling method can be used to construct the real⁃time simulation platform of MMC AC/DC system.