考虑发电成本最低的多端柔直自适应下垂控制策略研究

Study on self-adaptive droop control considering generation cost minimization for VSC-MTDC

针对多端柔性直流系统中的功率最优分配问题,提出了一种总发电成本最低的自适应下垂协调控制策略。建立以发电费用最低为目标函数的多端柔直经济调度模型,计及交流线路输电损耗、直流线路电压降、换流站有功调节容量等因素,并通过所提改进控制寻求模型的最优解。所设计的控制策略可在无需通信和上层调度参与的情况下,利用本地电压信号实现功率的自适应经济分配,并满足等微增率原则。最后,在PSCAD/EMTDC平台上搭建并联型四端柔直系统以验证所提控制策略的有效性。

A coordinated self-adaptive droop control for VSC-MTDC is proposed to optimize the active power distribution in this paper. To minimize the generation cost of the whole system, the economical dispatch model(EDM) of the DC grid is built including ac transmission power loss, voltage drop of dc line, power regulation capability of corresponding VSCs. The optimal solution of EDM is found through the improved scheme. Based on the equal incremental cost criterion, the strategy can make power allocated economically utilizing local DC-voltage signals. Meanwhile, no communication systems and centralized processing layer is required. Finally, a parallel-type 4-terminal MTDC system is formed on PSCAD/EMTDC simulation platform to validate its effectiveness.