基于虚拟磁链的直接功率控制在VSC-HVDC中的应用

Application of Virtual Flux Based Direct Power Control in VSC-HVDC Power Transmission

基于电压源换流器的高压直流输电系统(voltage sourced converter HVDC,VSC-HVDC)作为一种新型的直流输电技术,克服了传统直流输电系统中的换相失败、必须联结于有源网络等缺点,在新能源发电并网、孤岛供电、交联系统互联等应用场合具有广阔前景。研究了VSC-HVDC系统基于虚拟磁链定向直接功率的控制方法,根据推导的VSC电流矢量方程分析了空间电压矢量对有功功率、无功功率的作用机制,并由此改进了功率开关器件控制开关状态表的选择方案,仿真结果表明,新的开关状态表使得系统有功、无功功率调节更加平滑、快速,功率波动更小,从而提高了电力系统的稳定性。

As a new type of DC power transmission technology, the voltage sourced converter based HVDC （VSC-HVDC） power transmission system surmounts such defects of traditional HVDC power transmission system as commutation failure and needing to be connected to active network and so on, so it is suitable for application scenarios of gird-integration of new energy sources, power supply by islanded power system and interconnection of AC power grids. A virtual flux based direct power control （VF-DPC） method for VSC-HVDC power transmission system is researched, and according to the derived current vector equation of VSC the action mechanism of spatial voltage vectors on active power and reactive power is analyzed, and thus the selection scheme of switching table for power switching device control can be improved. Simulation results show that using the new switching table the regulation of active and reactive power can be smoother and faster and the power fluctuation is suppressed, thus power grid stability can be improved.