含柔性直流输电的交直流并列系统有功潮流优化方法

基于电压源换流器的高压直流输电技术,即柔性直流输电技术是近年来高压直流输电研究和应用的热点。但含柔性直流输电的交直流并列系统会使得电网的潮流分布更趋复杂。由于柔性直流输电系统能够实现有功无功的独立控制,对其有功功率指令值的分析有利于提高交直流并列系统的功率输送效率和效益。然而,目前电力调度中,该有功功率指令值的制定缺乏依据,为此提出了一种计及多目标的有功潮流优化方法。通过计及多个目标的约束,建立了相应的目标函数,利用模糊理论,给各个目标函数指定隶属函数,最终求解多目标优化函数得到交直流并列系统的有功潮流分配优化值。最后通过算例验证了所提方法的可行性。相比当前常常依据运行方式和运行经验笼统地制定有功功率指令值的做法,所提的多目标优化方法给出的指令值既能降低电网损耗,又保证了电网运行的安全稳定性。

An optimization method for active power flow in AC/VSC-HVDC parallel transmission systems

Voltage source converter (VSC) based HVDC is a hotspot in the study and application of HVDC in recent years. However, the AC/VSC-HVDC parallel transmission system has made the distribution of the power flow more complex in the power networks. As VSC-HVDC can control its active and reactive power flow independently, it would be useful to improve the efficiency of the AC/DC parallel transmission system by studying the optimal power flow in parallel AC/DC systems. This paper presents a multi-objective optimization method for active power flow in parallel AC/DC transmission systems. The objective functions are established considering the constraints of multiple objectives. Based on the fuzzy theory, the objective functions are specified to their corresponding membership functions, and then the optimal assigned value of active power of the AC/DC parallel transmission system can be found out. Finally, the result of the calculation example verifies the feasibility of the proposed method. Compared to the method of setting the active power flow in the AC/DC parallel system based on operating mode and operating experience, the multi-objective optimization method can not only reduce the network losses but also ensure the safety and stability of the operation of the AC/DC parallel power systems.