光伏DG接入配电网及微电网的过电压自动调节方法研究

针对光伏DG接入配电网因过电压而导致渗透率低的问题、微电网离网运行期间过电压问题,以及微电网在非计划孤岛状态下并网转离网暂态过电压问题,提出一种P/U下垂调节方法。当光伏DG接入配电网,该方法能避免光伏DG因过电压而退出运行。当光伏DG接入离网运行微电网,因负荷减少、DG出力增加等因素而导致过电压时,该方法可以实现无通信互连线的稳态离网能量平衡。当含光伏DG的微电网在并网转离网期间,该方法能够解决暂态过电压问题。首先推导电压偏差公式并分析过电压产生机理。其次介绍P-U下垂调节方法原理。最后为验证方法可行性,以光伏DG接入配电网为算例分析对象,搭建Matlab/Simulink仿真模型,并在逆变器样机上进行试验验证。结果表明P-U下垂调节方法可行有效。

Research on over-voltage automatic adjustment method of distributed photovoltaic source accessing to distribution network or microgrid

For the problem of low capacity penetration caused by over voltage, over voltage during the operation of islanded DG, and the transient over voltage between transition of DG both from islanded operation mode to grid-connected operation mode when photovoltaic DGs access to distribution network, this paper puts forward a kind of P/U droop control method, which can avoid photovoltaic DG exiting operation due to over voltage when it accesses to distribution network. When the load is reduced, the DG power increases and other factors causing over voltage in islanded DG including photovoltaic DG, the method can achieve the steady energy balance of islanded MG without control interconnections and also can solve the transient over voltage between transition of MG both from islanded mode to grid-connected mode. Firstly, the voltage deviation formula is given and over voltage generation mechanism is analyzed. Secondly, the P-U regulating method is introduced. And then in order to verify the feasibility of the method, taking photovoltaic DG accessing to distribution network as the object of analysis, the Matlab/Simulink simulation model and experiment are presented from the platform of photovoltaic inverter. The results show that P/U droop control method is effective.