适用于交直流系统电磁暂态仿真的三序网络动态等值方法及其在华东电网的应用

电磁暂态仿真能准确模拟交直流系统在不对称故障下的动态特性,为减小仿真计算量,提高仿真效率,需对大规模系统进行等值简化。提出了一种适用于交直流系统电磁暂态仿真的三序网络动态等值方法,该方法基于物理等效的动态等值技术,改进了低压网络标准等值结构,考虑了不对称短路故障时的负序和零序电流,采用了一种工程实用的等值发电机参数聚合和控制器模型选取方法,实现了等值前后主网各序网络阻抗相等,提高了等值系统在不对称故障下的仿真精度。该等值方法在网络简化过程中不会产生负电阻支路,同时避免了等值变压器负电阻和负电抗的出现,等值后的系统可直接用于电磁暂态仿真。最后开发了相应的等值软件,并将其应用于华东电网,等值结果验证了所提方法的有效性。

A Dynamic Equivalent Method for Three-Sequence Network Applied to Electromagnetic Transient Simulation of AC/DC System and Its Application in East China Power Grid

Electromagnetic transient simulation can accurately simulate the dynamic characteristics of AC/DC power system under asymmetric faults. In order to reduce the amount of simulating calculation and improve the simulation efficiency， it is necessary to simplify the large-scale power system. A dynamic equivalent method for three-sequence network applied to electromagnetic transient simulation of AC/DC system is proposed. On the basis of dynamic reduction technique for the physical equivalence， this method improves the standard equivalent structures of low-voltage networks， takes into account the negative sequence and zero sequence currents under asymmetric short-circuit faults， adopts a practical engineering method of parameter aggregation of equivalent generators and selection of controller models， makes the impedance of each sequence network of the trunk grid equal before and after the simplification， and gets better simulation accuracy of the equivalent system under asymmetric faults. This equivalent method does not produce negative resistance branches in the simplification process， and avoids the emergence of equivalent transformers with negative resistance or reactance. Thus， the equivalent system can be directly used in electromagnetic transient simulation. Finally， the corresponding equivalent software is developed and applied to the equivalence of East China Power Grid. Simulation results verify the effectiveness of the proposed method.