MMC-HVDC向无源网络供电的停机策略

A Shutdown Control Strategy of Modular Multilevel Converter Based HVDC Transmission System Supplying Power for Passive Network

修正了能馈阶段直流参考电压下降时的最低值,计算了系统整体停机时间,推导了能耗阶段内能耗电阻选取的表达式。在能馈阶段,考虑桥臂冗余子模块在内,将投入模块数和直流电压协调配合,提出了一种新的停机策略。该策略不仅可以最大程度地将电容中的储存能量反馈至电网,而且大大降低了能耗电阻的耐压等级和功率等级,同时电容电压可以精确地控制在安全电压以下,并且停机速度更快。最后,在Matlab中搭建了基于MMC-HVDC向无源网络供电的仿真系统,仿真结果表明了所提停机策略的有效性。

The minimum value of DC voltage reference during energy feedback stage is modified and the overall shutdown time of modular multilevel converter （MMC） based HVDC （MMC-HVDC） transmission system is calculated, and the expression for choosing energy consumption resistor during energy consumption stage is derived. Considering redundant submodules in bridge arms during energy feedback stage, a new shutdown strategy of MMC-HVDC transmission system, in which the DC voltage is coordinated to the used modules, is proposed. Using the proposed strategy, not only the energy stored in the capacitors can be fed back to power grid farthest but also the requirement to the power level and withstand voltage of energy consumption resistor can be decreased, meanwhile the capacitor voltage can be accurately controlled below the safety voltage and the shutdown process can be accelerated. Finally, a simulation system of MMC-HVDC transmission system supplying power for passive network is constructed in Matlab environment, and simulation results show that the proposed shutdown strategy is effective.