考虑三相有功不平衡度的无功电压集中控制策略

我国低压配电网中的负荷过重且分配不均,近年来,大量光伏的接入更进一步加剧了三相不平衡和低电压问题。针对三相不平衡问题,换相开关能通过调整负荷的方式从根本上进行解决;而大量光伏逆变器也可作为有效的无功调节资源,但目前其无功电压调节潜力尚未被开发利用。因此,以换相开关和光伏逆变器为主要调控设备,文中提出了考虑三相有功不平衡度的无功电压集中控制策略,其中,所提换相开关的控制策略综合考虑了配变低压侧三相有功功率偏差度和换相开关动作次数,所搭建的光伏逆变器无功优化模型以线路损耗最小化为目标,经仿真验证,所提换相开关控制策略可有效降低三相不平衡度、提升电压,光伏逆变器的无功优化模型可进一步降低线路损耗、改善电压。

A Reactive Voltage Centralized Control Strategy Considering Three-phase Unbalance of Active Power

In China's low-voltage distribution network,the load is too heavy and unevenly distributed.In recent years,the access of a large number of photovoltaics has further aggravated the three-phase unbalance and low voltage problems.For the three-phase unbalance problem,the commutation switch can fundamentally solve it by adjusting the load;and a large number of PV inverters can also be used as an effective reactive power regulation resource,but its reactive voltage regulation potential has not yet been tapped and explored.Therefore,with the commutation switch and photovoltaic inverter as the main control equipment,a reactive voltage centralized control strategy considering three-phase unbalance of active power is proposed in the paper.In the strategy,the control strategy of the commutation switch comprehensively considers the deviation of three-phase active power on the low-voltage side of the distribution transformer and times of the switches action,and the reactive power optimization model of photovoltaic inverter is aimed at minimizing the line loss.The simulation proves that the regulation of the commutation switch in the strategy can effectively reduce three-phase unbalance and improve voltage,the optimization of reactive power that photovoltaic inverter outputs can further reduce line loss and improve voltage.