基于电压源换流器的多端柔性直流输电系统拟交流最优潮流

Quasi-AC optimal power flow for voltage source converter-based multi-terminal DC system

为便于求解含多端柔性直流输电系统的最优潮流,提出一种拟交流最优潮流计算方法。通过分析电压源换流器的工作原理,建立了计及换流站有功损耗的交流电源型等值电路。针对系统直流网络部分设定约束条件,将其等效为特殊的交流网络。为降低计算复杂度,对换流站的能量耦合方程进行了线性化处理。基于此,含多端柔性直流系统可视为纯交流系统并进行潮流计算。考虑到交流系统最优潮流问题具有非凸特性,将其最优潮流模型松弛为半定规划模型。实验结果表明,所述方法能够有效求解多端柔性直流系统最优潮流问题。

A quasi-AC Optimal Power Flow(OPF)solution is proposed to solve the OPF problem of a Voltage Source Converter-based Multi-Terminal DC(VSC-MTDC)system.By analyzing the principle of the VSC,an equivalent model considering the loss of the VSC station is established with AC power supply.Constraints are added to the DC grid to equate it to the special AC grid.The energy coupling equation of the VSC is linearized to simplify the difficulty.Based on the above,the power flow of a VSC-MTDC system can be calculated as an AC system.Since the OPF problem of an AC system is non-convex,the OPF model is relaxed to a semi-definite programming model.The test result shows that the proposed method can solve the OPF problem of a VSC-MTDC system.