微电网孤岛模式下无功分配及电压优化分层控制策略

针对在微电网孤岛模式下并联运行的分布式电源采用传统下垂控制策略时存在无功功率受并网线路阻抗影响较大、电压偏离额定值等问题,提出了微电网孤岛模式下无功分配及电压优化分层控制策略,将微电网优化控制过程分为两层:初级控制层针对分布式电源无功功率受并网线路阻抗影响较大问题,提出变系数法下垂控制策略,根据下垂特性和线路特性约束方程调整下垂系数,实现无功功率精确分配;二级控制层应用多智能体一致性算法维持微电网电压稳定。仿真模型使用PSCAD/EMTDC搭建,结果表明,分层优化策略使无功功率合理分配的同时提高了微电网电压水平。

Hierarchical Control Strategy for Reactive Power Distribution and Voltage Optimization in Island Mode of Microgrid

In the island mode of microgrid,when the traditional droop control strategy is adopted for the distributed generator in parallel operation,the reactive power is greatly affected by the grid line impedance,and the voltage deviates from the rated value.Therefore,this paper proposes the hierarchical control strategy for reactive power distribution and voltage optimization in the island mode of microgrid,and divides the optimization control process of microgrid into two layers.In the primary control layer,a droop control strategy based on variable coefficient method is proposed to solve the problem that the reactive power of distributed generator is greatly affected by the impedance of grid connected lines,and the precise distribution of reactive power is realized by adjusting the droop coefficient according to the droop characteristic and the line characteristic constraint equation.The second control layer uses the consistency algorithm of multi-agent system to keep the microgrid voltage in the rated value.The simulation model was built in PSCAD/EMTDC,and it was shown that the proposed hierarchical optimization strategy can reasonably distribute the reactive power and improve the voltage quality of microgrid.