一种适用于交直流互联系统电磁暂态仿真的动态等效方法

摘要

In the electromagnetic transient simulation of AC/DC interconnected power system, it is necessary to conduct a dynamic equivalent for the low voltage level (220 kV or below) AC power system, which can reduce the scale of power system and improve the simulation efficiency. This paper proposes a dynamic equivalent method for mid-low voltage level network in AC/DC interconnected power system. Based on reserving power flow and dynamic characteristics of backbone network before and after equivalence, the method constructs the structure of the equivalent node on the backbone network for reducing the low voltage level network. The determination of the parameter of the elements in the equivalent node structure is given. The computation of reducing network is simple. And there will not be negative resistance in the equivalent power system, so the equivalent network can be used in electromagnetic transient simulation directly. This method is applied to Shandong power grid. Through the comparison of power flow, short circuit current of buses on backbone network and transient behavior variations of power system pre and post the equivalence, it is proved that the proposed method is reasonable and effective.%在进行交直流互联系统电磁暂态仿真时,常需要对交流系统中220 kV及其以下电压等级的电网进行动态等效,以减小系统规模,提高仿真效率.提出一种针对交直流互联系统中低电压等级网络的动态等效方法,该方法基于等效前后系统主干网架潮流和动态特性不变的原理,构建了低电压等级网络等效后的主干网节点结构,并给出了等效结构中各元件参数的确定过程.采用该方法化简网络时计算量小,且不会产生负电阻支路,等效后的网络可直接用于电磁暂态仿真.应用该方法在机电暂态环境中对山东电网进行动态等效,通过对比等效前后系统潮流,主干网母线短路电流以及故障后系统暂态行为变化等情况,证明了所提动态等效方法的合理性和有效性.