高比例光伏与配电网超高次谐波交互影响研究

Interaction of high proportion photovoltaic and supraharmonic in distribution network

高比例光伏并网显著增加了配电网超高次谐波含量,高比例光伏与配电网之间的交互影响相较于单台光伏并网更加复杂,电网安全运行稳定性降低。为揭示高比例光伏并网下的超高次谐波特性,文中对高比例光伏并网与配电网超高次谐波交互影响进行了分析。首先,针对高比例光伏接入配电网的超高次谐波传播特点进行理论研究,并综合电网背景谐波、光伏控制电路影响建立可准确反映分布式光伏超高次谐波电流的动态数学模型。在此基础上,搭建PSCAD仿真模型,重点分析多台光伏逆变器间以及电网背景与光伏逆变器间的超高次谐波交互影响。最后,通过福建泉州某集中接入的屋顶光伏超高次谐波实测数据验证了分析结果的正确性。

The high proportion of grid-connected photovoltaics(PVs)leads to a dramatical increase of supraharmonic emissions at distribution network.The influence of supraharmonic interaction between grid-connected PVs and distribution network is much more remarkable than that in single PV grid-connected system.So the high proportion of grid-connected PVs reduces the stability of the grid.In order to reveal the characteristics of supraharmonic emission at high proportion of PVs grid-connected,the effect of PVs connecting to grid on supraharmonic emission is discussed.Firstly,the propagation of supraharmonic current at high proportion of grid-connected PV is described.Considering background harmonic emission of grid and control circuits of PVs,a mathematic model is built to calculate the value of supraharmonic currents and summarize the law of supraharmonic propagation at high proportion of grid-connected PVs.On the basis of the model built by PSCAD simulation platform,the supraharmonic emission from individual PVs is obtained.The model is also used to show the influence of backgrounds and PVs on supraharmonic emission.The last but not the least,the model is verified,based on measured date of concentrated PV access in Quanzhou city,Fujian Province.