构网型新能源-储能联合并网系统LVRT控制策略研究

Research on LVRT Control Strategy of Combined Grid-connected System with New EnergyEnergy Storage Based on Grid-forming Converters

针对构网型变换器控制下的新能源-储能联合并网系统低电压穿越问题,提出一种基于传统低电压穿越策略的附加电压限制器控制方案。首先分析传统基于电流限制的低压穿越策略存在的不足,当故障持续时间较长时仅设置电流限制将容易导致同步失稳问题;然后提出附加电压限制器的改进低压穿越策略,以抑制更长时间尺度下的故障电流,提升故障下的同步稳定性;最后在Matlab/Simulink中搭建新能源-储能联合并网系统的仿真模型对所提方案进行验证。实验结果显示该方案确保了电网发生三相对称跌落故障时新能源储能联合并网系统能够不脱网运行,有效提升故障期间系统的同步稳定性。

Aiming at the low voltage ride through(LVRT)problem of the combined grid-connected system with new energy-energy storage under the control of the grid-forming converter,an additional voltage limiter control scheme based on the traditional LVRT was proposed.Firstly,the shortcomings of the traditional LVRT strategy based on current limitation was analyzed.When the fault duration is long,only setting current limitation would easily lead to synchronization instability.Then,an improved LVRT strategy with additional voltage limiter was proposed to suppress the fault current under a longer time scale and improve the synchronization stability under the fault.Finally,a simulation model of new energy-energy storage combined grid system was built in Matlab/Simulink to validate the proposed scheme.The experimental results show that the proposed scheme can ensure that the new energy-energy storage combined grid-connected system not be taken off-grid during the three-phase symmetrical sag fault,and effectively improved the synchronization stability of the system during the fault.