基于实时网络潮流优化与传输功率均衡控制的VSC-MTDC优化下垂控制策略

Optimal Droop Control Strategy for VSC-MTDC System Based on Real-Time Network Power Flow Optimization and Transmission Power Balance Control

通过分析多端网络经济运行与安全运行的本质要求,以构建直流网络损耗实时优化模型为基础,综合考虑节点直流电压越限问题,实时更新VSC-MTDC系统下垂系数,以保证系统在较小网损状态下运行。引入下垂换流站传输功率均衡化控制环节与系统防振荡控制环节,从而协调处理直流网络损耗、换流站功率裕度、直流电压越限以及过于频繁改变下垂系数引发的系统振荡等问题。最后,基于PSCAD/EMTDC搭建7端柔性直流输电系统仿真模型,算例仿真结果验证了所提出的控制策略的有效性。

By analyzing the essential requirements of the economical operation and safe operation of multi-terminal DC(MTDC)system,based on the real time optimization model of the DC network loss,and considering the voltage limit of the DC network nodes,the droop coefficient of the system is updated in real time to ensure that the system runs in a small network loss state.And the transmission power balance control link and system anti-oscillation link are introduced into the droop converter station,so as to coordinate the problems such as the loss of DC network,the power margin of the converter station,the limit of the DC voltage and the oscillation of the system droop coefficient too frequently.Finally,a simulation model of 7 terminal flexible HVDC transmission system is built under PSCAD/EMTDC platform.The simulation results verify the effectiveness of the proposed control strategy.