抑制电压波动与规避频率越限的孤岛微电网并网预同步方案

传统孤岛微电网并网预同步过程中存在因风光电源出力变化而导致的电压波动问题,以及因比例-积分(PI)参数取值不当导致的频率越限问题.为解决这些问题,首先,对储能系统V/f控制策略引入负荷电压与电流的前馈扰动补偿以平抑电压波动;其次,基于Simplex算法优化PI参数以兼顾预同步过程中的并网速度与频率波动,并设计了离线优化与在线查表相结合的优化PI参数取值方法;然后,设计了兼顾电压波动与频率越限的孤岛微电网预同步优化控制方案;最后,利用仿真实验证实了该孤岛微电网并网预同步方案可实现相位迅速同步,并可有效抑制电压波动与规避频率越限风险.

Pre-synchronization Scheme with Voltage Fluctuation Suppression and Frequency Out-of-limit Avoidance for Grid Connection of Islanded Microgrid

During the traditional pre-synchronization process for grid-connection of islanded microgrids, there exist the voltage fluctuation caused by the output variation of the wind and photovoltaic distributed generators, and the frequency out-of-limit risk caused by the improper proportional-integral (PI) parameters. To solve the above problems, firstly, the feedforward disturbance compensation of the load voltage and current is introduced into the V/f control strategy of the energy storage system to suppress the voltage fluctuation. Secondly, based on the Simplex algorithm, the PI parameters are optimized to take into account the grid-connected speed and frequency fluctuation in the pre-synchronization process, and the optimized PI parameter selection method combining off-line optimization and on-line lookup table is designed. Thirdly, a pre-synchronization optimized control scheme for the islanded microgrid considering both the voltage fluctuation and frequency out-of-limit risk is proposed. Finally, the simulation experiment proves that the pre-synchronization scheme for the grid connection of islanded microgrids can realize the fast phase synchronization and effectively suppress voltage fluctuation and avoid frequency out-of-limit risk.