兼顾柔性直流配电系统经济成本的优化下垂控制策略

Dual-Objective Optimal Droop Control Strategy for Flexible DC Distribution Systems

柔性直流配电系统运行方式多样且源荷功率波动具有高频随机性。为解决传统下垂控制未计及运行损耗、功率分配不合理和电压动态调节不理想等问题,首先分析系统运行损耗最小时的潮流优化方法,推导出经济下垂系数优化分配各站功率。为减小直流电压偏差,尽量避免换流站参数越限,提出下垂系数按电压裕度和换流站实时最大功率裕度自适应调整。最后以系统功率波动时直流电压偏差大小作为判断条件,给出优化下垂系数的选择方法,提出一种兼顾系统经济成本和换流站参数裕度的优化下垂控制策略。在PSCAD上搭建双端柔性直流配电系统仿真模型,不同运行工况的仿真结果验证了该策略的有效性。

A flexible DC power distribution system operates in various ways and the source-load power fluctuations have high-frequency randomness.In order to solve the problems of low power quality,unreasonable power distribution and unsatisfactory dynamic voltage regulation under traditional droop control,a dual-objective optimal droop control strategy considering both economic performance and converter power margin is proposed.Firstly,the power flow optimization is analyzed when the system running loss is minimum,the droop coefficient of economic distribution is derived,and the power of each station is optimized.In order to avoid over-limit of the converter station parameters and reduce the static deviation of DC voltage,it is proposed to adaptively adjust the droop coefficient by considering the voltage margin and the real-time maximum power margin of the converter station.Finally,according to the DC voltage deviation when the system power fluctuates,the selection method for optimizing the droop coefficient is proposed.The simulation model of double-ended flexible DC power distribution system is built in PSCAD.The simulation results of different operating conditions verify the effectiveness of the strategy.