大型光伏电站集电系统谐波传递网络分析

Harmonic Transfer Network Analysis of Large-Scale Photovoltaic Power Plant Electricity Energy Collection System

大型光伏电站中,每组并网逆变器系统的输出功率(电流)经站内集电系统汇集后向外送出。文献研究表明,即使单台并网逆变器的输出电流谐波较小,多台并网逆变器并联后输出电流的谐波也有可能超标。针对典型大型并网光伏电站拓扑结构,建立了详细考虑站内集电系统结构的大型光伏电站谐波传递网络模型。用节点导纳法在M ATLAB中对算例进行了谐波潮流计算,得出各个节点各次谐波电压相对于该点基波电压的放大倍数,并选取主变压器低压侧节点作为分析对象,与忽略集电系统内部结构时的计算结果作比对,发现谐波电压放大特性发生明显改变。最后分析了集电系统内部LCL滤波器及电缆线路参数对传递网络谐波电压放大特性的影响。

In large-scale photovoltaic（ PV） power plant,the output power of every PV grid-connected inverter system is collected by electricity energy collection system and then is put into electricity grid. Previous studies have demonstrated that the harmonic problem may occur when PV inverters run in parallel even if all the PV inverters individually satisfy the standards.Considering the electricity energy collection system,this paper builds the model of harmonic transfer network for typical topological structure of large-scale grid-connected PV power plant. Using node matrix method,this paper calculates the harmonic power flow of a given calculation example in MATLAB and gets the fundamental and harmonic voltage amplitudes of every node. Taking the node of the low voltage side of main transformer as the study object,this paper compares the calculation result with that of neglecting the structure of the electricity energy collection system,w hose results show that the voltage amplification property obviously changes. Finally,this paper analyzes the influence of the parameters of LCL filter and cable in the electricity energy collection system on the voltage amplification property of the harmonic transfer network.