低压微电网孤岛模式下改进下垂控制策略

在孤岛运行的低压微电网中，传统下垂控制会导致频率和电压偏离额定值、无功功率分配精度较低等问题，为此提出了无稳态误差的有功—频率下垂控制和综合改进的无功—电压控制策略，分析了在有功—频率下垂控制中引入隔直环节实现消除频率稳态误差的原理，综合分析了下垂系数、虚拟电抗、输出电流补偿等无功—电压下垂改进措施对无功分配精度、系统稳定性和电压跌落的影响，实现了稳态时微电网频率无偏差，提高了分布式电源之间无功功率分配精度，确保了电压波动在允许范围内。仿真算例验证了所提出的控制策略的有效性，为低压微电网孤岛模式下的下垂控制提供了参考。

Improved Droop Control Strategy for Low Voltage Microgrid under Island Mode

In the islanded low voltage microgrid, the traditional droop control leads frequency and voltage excursions and low reactive power distribution accuracy. Power-frequency droop control without steady-state error and improved reactive power-voltage control strategies are put forward. The frequency steady-state error elimination principle is analyzed, which the DC isolation link was introduced in power-frequency droop control. The impacts on the reactive power distribution accuracy, system stability and voltage sag caused by droop control coefficient, virtual reactance and output current compensation are analyzed. Frequency excursion is eliminated and reactive power distribution accuracy is improved, and voltage can be maintained in the normal range. Simulation results verified the effectiveness of the proposed improved droop control, which provides reference for the droop control of the low voltage standalone microgrid.