柔性直流电网的快速电磁暂态仿真

柔性直流电网含多个模块化多电平换流器与直流断路器,需要快速准确的换流器与直流断路器仿真模型。为提高模块化多电平换流器的仿真速度,利用电容能量均分的思想简化子模块均压策略,并准确保留桥臂闭锁与不闭锁时的外特性,提出了一种能量均分模型。针对级联全桥型直流断路器,给出一种断路器支路子模块串等值电路简化方法,提出了一种快速仿真模型。在PSCAD/EMTDC中搭建模型并进行了电磁暂态仿真,验证了所提出模型的准确性与快速性。

Fast Electromagnetic Transient Simulation for Flexible DC Power Grid

Flexible DC power grid contains a number of modular multilevel converters and DC breakers, hence fast and accurate models of converter and DC breaker are needed. For the sake of accelerating the simulation of modular multilevel converters, an energy equipartition model is proposed by equal distribution of the power of capacitor to simplify the voltage balancing control and retaining the external characteristic of the bridge arm in blocked and unblocked status. As for the cascaded full-bridge DC breaker, a fast simulation model is developed by simplifying the full-bridge sub-modules in breaker sub-circuits. Electromagnetic transient simulations on PSCAD/EMTDC are carried out to verify the accuracy and acceleration of the proposed model. This work is supported by National Key Research and Development Program of China(No. 2016YFB0900600)and National Natural Science Foundation of China(No. 51577148).