一种考虑暂态稳定性的VSC-HVDC系统优化控制策略

Optimized Control Strategy of VSC-HVDC System Considering Transient Stability

提出一种考虑暂态稳定性的含同步逆变器高压直流输电(SHVDC)系统优化控制策略。首先将同步逆变器的思想运用到含电压源换流器的高压直流输电(VSC-HVDC)中,然后建立了VSC-HVDC系统的双机等值模型;在此基础上设计了一种具有下垂特性的类同步机控制器,代替传统的外环电压内环电流控制器以改善系统的暂态特性;进一步提出一种考虑发电机功角变化的Bang-bang控制策略,此策略可进一步提高系统的暂态稳定性。最后在PSCAD/EMTDC中搭建含VSC-HVDC交直流混联系统并进行仿真验证。仿真结果表明所设计的控制器对系统的暂态特性有一定的改善作用,若进一步加入所提出的Bang-bang控制策略则可进一步提高系统的暂态稳定性。

An optimized control strategy is proposed when considering the stability of synchronverter-based HVDC （SHVDC） system. Firstly, the thought of synchronverter is used in VSC- HVDC system, an equivalent mathematic model of VSC- HVDC system is established ; Secondly, a controller which similar to the droop characteristic of synchronous machine is designed to take place of the traditional controller with inner current loop and outer voltage loop with purpose of improving the transient characteristic of power system.Further, a Bang-bang control strategy which based on the variation of power angle is put forward. The strategy can enhance the system damping effectively and consequently improve the transient stability of system. In the end, PSCAD/EMTDC is adopted to conduct simulation tests based on AC/DC system equipped with VSC-HVDC. Simulation results show the designed controller has improvement in the transient characteristics of system, and the additional Bang-bang control strategy can further improve the transient stability of the system.