基于等微增率法的混合微电网无功协调控制

Coordinated Control of Reactive Power for Hybrid Microgrid Based on the Method of Equal Incremental Principle

在馈线潮流控制(FFC)和单元输出功率控制(UPC)两种控制模式下的混合微电网中,FFC模式下分布式电源(DG)的无功裕量不能满足增加的无功负载时,会引起微电网和大电网之间馈线无功潮流的变化,且馈线无功潮流值越大,脱网时公共连接点(PCC)电压偏差越大。为此,提出了一种考虑微电网内部节点电压稳定性的多台DG无功协调控制策略。该策略以FFC模式下DG为主要补偿设备,当不能满足负载需求时,采用等微增率法求解优化模型,从而确定UPC模式下DG无功输出参考值。算例结果表明,该控制策略能在维持微电网与大电网之间馈线无功潮流恒为最小值的同时,使得微电网内部节点电压更稳定。

In the hybrid microgrid under two kinds of control mode, the feeder flow control （FFC） and the unit output power control （UPC）, it will cause the change of the feeder reactive trend between the microgrid and grid when the reactive power margin of the distributed generation （DG） under FFC mode cannot satisfy the increase of reactive load, and the larger the feeder reactive trend, the greater the voltage deviation of the point of common coupling （PCC） when appearing off-grid. So, this paper proposed a coordinated control strategy for reactive power of multiple DGs considering the voltage stability of the internal nodes of microgrid. The DG under FFC mode was taken as the main compensation equipment. When the load demand cannot be satisfied, the optimization model was solved by using the equal incremental method so as to determine the reactive output reference value of DGs under UPC mode. The example result shows that the control strategy not only stabilizes the voltage of the internal nodes of the microgrid, but also the feeder reactive trend between the microgrid and grid is always the minimum constant.