The Research On Harmonic Distribution Characteristics And Resonance Degradation Of Photovoltaic Power Station

In recent years,with the steady progress of the global energy Internet construction,the installed capacity of photovoltaic power generation in China has been expanding,and the grid harmonics show new features such as wide frequency domain,high frequency and so on,There is a phenomenon of resonance deterioration caused by the interaction between multiple generating units in the power station,and the harmonic current and voltage of photovoltaic power station are prone to generate series parallel resonance amplification in the transmission process of power transmission and distribution system,which leads to the deterioration of power quality.The power quality problem caused by photovoltaic power station connected to the grid has become the focus of the industry.In view of the current situation that there are many kinds of harmonics in wide frequency domain and they are easy to occur mutual coupling,this thesis first studies the harmonic characteristics and distribution of photovoltaic power plant,builds the photovoltaic power plant model,introduces the functions and characteristics of its basic modules,analyzes its harmonic output characteristics,and then connects the photovoltaic power plant model to different positions of ieee34 node test system,and analyzes The influence of different access positions on the distribution network harmonic current and voltage distribution.In order to study the resonance phenomenon of single and multi-photovoltaic grid-connected system,the resonance degradation phenomenon of the grid connected system is analyzed.According to the system structure and parameters of photovoltaic power station,the impedance model is established,and the impedance stability of the interaction system between grid connected inverter and power grid is analyzed.Based on the established model,the mode method is used to analyze the grid connected system of single and multiple photovoltaic power stations,and the resonance frequency,the highest excitation point,the highest observation point and the participation factor of the system are obtained,and the resonance center and the resonance influence range of the system are determined.Based on the analysis of the resonance phenomenon in the grid connected system of photovoltaic power station,this thesis further studies the resonance degradation phenomenon in the transmission and distribution system.Relying on the established model,the thesis studies the change and degradation degree of the harmonic magnification of the transmission and distribution system when the photovoltaic power station is connected to the grid under different line distance and different harmonic times,and analyzes the access of photovoltaic power station to the distribution network The degree of resonance amplification and its influencing factors.The simulation results verify the feasibility of the harmonic resonance degradation analysis method proposed in this thesis and the effectiveness of the conclusions.It provides a theoretical basis for the harmonic control of photovoltaic power plant,and is of great significance for the safe and stable operation of the whole system.