直流微电网低电压穿越控制仿真研究

为提高直流微电网低电压穿越能力和稳定性,提出正负序分离的直流微电网低电压穿越控制策略。通过变换器整体数学模型,将电网电压和并网电流进行正负序分离,依据电压跌落程度设置有功和无功电流设置。建立基于PSIM仿真模型针对该低电压穿越控制策略进行仿真分析,实验结果表明,当网侧发生单相和两相不对称电压跌落时,采用该策略系统可继续保持在并网运行状态,系统有功输出减少到1.8kW,无功功率的输出增加到0.8kVar附近,有利于电网电压的恢复,实现低电压穿越。

Simulation study of LVRT control strategy for DC micro-grid

In order to improve the low voltage crossing ability and stability of DC micro-grid,a low-voltage crossing optimization control strategy based on positive and negative sequence separation is proposed.The mathematical model of the whole system was established,the collected voltage and current signals were separated into positive and negative sequence,and the three-phase symmetric component was transformed into two-phase rotating coordinate system.By converting the positive sequence component into DC monitoring voltage sag amplitude,the reference value of positive and negative sequence current is calculated.The simulation analysis of the low-voltage crossing control strategy under the condition of asymmetric fault by PSIM software shows that when single-phase and two-phase asymmetric voltage drops occur in the grid,the system can continue to operate in the grid-connected state,and the active power output reduced to 1.8 kW and the reactive power output increased to around 0.8 kVar,which is conducive to the restoration of the grid voltage and the realization of low voltage crossing.