高压直流输电系统接入下的交流系统不对称故障下序网等值及短路电流算法

随着高压直流输电技术的日益发展，交直流混联系统的相互影响已成为高压直流输电领域的研究重点。针对含高压直流输电系统接入的交流系统，本文研究了其在不对称故障下的故障分析方法，提出了LCC-HVDC在交流侧的复合序网等值模型以及短路电流计算方法。首先搭建了基于不对称工况下的LCC-HVDC开关函数模型，随后根据开关函数模型建立了相应的LCC相量模型，并推导了LCC交流侧复合序网的计算方法。最后将LCC复合序网模型与交流系统不对称故障的边界条件结合，提出了适用于求解含高压直流输电系统接入的交流系统不对称故障短路电压电流的迭代算法并进行了仿真验证。仿真结果表明，本文提出的故障电流算法均可以满足工程计算要求。

Sequence Network Equivalence and Short Circuit Current Algorithms for Asymmetric Faults of AC Systems with HVDC Connection

With the development of HVDC technology, the interaction between AC and DC hybrid systems has become the research focus. For AC systems with HVDC system connection, its fault analysis method under asymmetric faults is studied, and the equivalent model of LCC-HVDC composite sequence network on AC side and the calculation method of short-circuit current are proposed. Firstly, the LCC-HVDC switching function model under asymmetric conditions is built. Then, the phasor model of LCC is established based on the switching function model, and the calculation method of LCC Compound sequence network is deduced. Finally, combining the LCC compound sequence network model with the boundary conditions of asymmetric faults in AC system, an iterative algorithm for solving the short-circuit voltage and current of asymmetric faults in AC system with HVDC system access is proposed and verified by simulation. The simulation results show that the proposed fault current algorithm can meet the requirements of Engineering calculation.