Study on Simulation of Electrical Characteristics of Grid-connected Photovoltaic Failure

Abstract

At present, the research on the grid connection characteristics of photovoltaic system mainly focuses on the steady-state characteristics of photovoltaic grid connection interface. Such as photovoltaic grid connected power quality characteristics, low voltage ride through characteristics, islanding detection methods and so on. Under the condition of grid failure, the voltage and current characteristics of photovoltaic grid connected system have not formed an accurate analysis model, which brings great trouble to the fault analysis and relay protection setting calculation of large-scale photovoltaic grid connected system. With the continuous improvement of the penetration rate of grid connected photovoltaic power generation, the research focus of photovoltaic power generation has gradually shifted from the steady-state characteristics of power quality of photovoltaic power generation to the transient characteristics of grid operation faults caused by grid connected power generation. Because the working principles and connection modes of various photovoltaic power generation are quite different from those of traditional generators, the research methods and tools of conventional power system fault analysis and setting calculation are difficult to be applied to large-scale photovoltaic grid connected systems. Therefore, it is urgent to study the transient characteristics of large-scale photovoltaic access ports in power system on the basis of in-depth understanding of power system fault calculation, photovoltaic power generation electromagnetic transient modeling method and simulation principle. The current research mainly focuses on the following three aspects: first, the dynamic mechanism analysis of photovoltaic grid connection and the mathematical model of electromagnetic dynamics; the second is the characterization of photovoltaic grid connected port based on dynamic simulation model; the third is the research on the interaction characteristics of photovoltaic and power system under typical application scenarios. The research results could further improve the stability of photovoltaic power station and power grid and ensure the safe and efficient operation of the whole system. It also provides theoretical basis and technical support for grid connected operation detection technology of photovoltaic power station. It can also provide reliable parameters for the power grid in line with the operation characteristics of renewable energy generation without changing the classical calculation methods such as relay protection setting calculation. It aims to enhance the operational ability of system and solve a series of problems caused by the connection of renewable energy to the power grid, which has irreplaceable special significance for the development of the power industry in the future.