分布式光伏系统并网对配电网电压的影响及电压越限治理方案

Influence of Distributed PV Systems on Voltage in Distribution Network and Countermeasure of Voltage Beyond Limits

随着大规模分布式光伏系统并网,配电网电压问题成为分布式光伏发展的最大挑战之一.以辐射状结构配电网为研究对象,从电压降落角度研究分布式光伏系统并网前后配电网电压分布的变化,分别分析了单个和多个光伏系统并网对配电网电压的改变,探讨了改变电压分布的各种因素,包括接入容量、接入位置、负荷大小、工作方式和接入方式.通过美国PG&E69节点系统对理论分析进行了验证,得出线路电压随光伏系统并网而升高,且升高幅度与负荷分布和光伏出力有密切关系的结论,并提出了配电网电压越限的治理方案,该方案充分利用逆变器的剩余容量吸收无功,有效解决了分布式光伏系统并网引起的电压越限问题.

With the large scale distributed photovoltaic systems connected to the grid, the voltage problem of distribution network becomes one of the biggest challenges in the development of distributed photovoltaic. Taking the radial distribution network as the research object,from the viewpoint of voltage drop in power grid,the paper studies the voltage variation of distribution network before and after the connection of photovoltaic systems to distribution network. The influences of connecting single photovoltaic system and multi photovoltaic systems to distribution network on voltage of distribution network are analyzed respectively. The factors that affect the distribution network voltage distribution are discussed, including the access capacity, access location, load size, operation mode and access mode. The theoretical analysis is verified by America PG＆E69 nodes system,and the obtained conclusions are as follows：the photovoltaic systems increase the line voltage and the voltage variation is directly related to the distribution of loads and the output of photovoltaic systems. Meanwhile, the countermeasure of voltage beyond limits in distribution network is put forward. The countermeasure can make full use of the residual capacity of the inverter to absorb reactive power, and solve effectively the problem of voltage beyond limits caused by distributed photovoltaic systems connected to the grid.