一种工程实用的电力系统等值方法

硬件在环试验中,为了兼顾仿真规模和交直流相互影响,需要对交流系统进行等值。基于等值前后系统短路容量一致原理,提出一种新型交流大电网等值方法。根据等值节点的短路电流构建等值发电机的额定容量及并网阻抗参数;根据短路电流大小与系统动态特性强弱关系,提出一种基于短路电流贡献率的新判据;采用该判据选择等效发电机的主导控制器类型,并计算控制器的参数;对静态Ward等值进行修正,消除负电阻及发电机有功输出为负的情况。通过算例对比等值前后系统电压、功率流动、短路容量以及故障后动态响应特性,验证了所提方法的有效性。

Power system equivalence for practical engineering

AC system equivalence is needed in HIL(Hardware-In-Loop) test to give the considerations of simulation scale and interaction between AC and DC, for which, a method of large-scale AC system equivalence is proposed based on the principle that the short circuit capacities before and after equivalence should be consistent. The rated capacity and access reactance of equivalent generator are set according to the short circuit current of equivalent node. A new criterion is proposed based on the short circuit current contribution ratio according to the relationship between short circuit current and dynamic system characteristics, which is used to choose the dominative controller of equivalent generator and calculate the controller parameters. The static Ward equivalence is improved to eliminate the conditions of negative resistance and negative generator active power output. As an example, the system voltages, power flows and short circuit capacities before and after equivalence are compared and the post-fault dynamic response characteristics are analyzed, verifying the effectiveness of the proposed method.