用于多微源低压微电网的虚拟阻抗反下垂控制

摘要

The performance of load power distribution according to the proportion of DGs' capacities to is very critical for the stability and high efficiency of the low-voltage microgrid system with multiple micro sources in different rated capacities. Due to the unbalanced line impedances, P-V/Q-f droop control strategy always has active power sharing issues. The application of virtual impedance method can reduce this power sharing error, while it may lead to great voltage drop. As a result, an improved P-V/Q-f droop control strategy based on the introduction of virtual impedance is proposed to achieve a reasonable sharing of power according to DGs' capacities and ensure the control stability of the voltage and frequency at the same time. Finally, a low-voltage microgrid system with six specific micro sources is constructed in PSCAD/EMTDC platform, where the simulation and analysis under various operating conditions and in island/grid-connected mode are carried out. The simulation results verify the effectiveness of the control strategy comprehensively.%针对含有多个不同额定容量微源的低压微电网系统,其负荷功率按微源容量比例进行分配的性能对系统的稳定及高效运行十分重要.反下垂控制策略因受微电网线路阻抗不平衡的影响存在有功功率分配误差问题,应用虚拟阻抗可抑制这种误差,但传统的虚拟阻抗方法会导致较大的电压跌落.因此,提出一种引入虚拟阻抗的新型反下垂控制方法,在实现功率按容量比例分配的同时保证电压和频率的稳定控制.最后,在PSCAD/EMTDC平台上搭建含有六个具体微源的低压微电网系统进行孤岛/并网模式下多工况的仿真分析,较为全面地验证了该控制策略的有效性.