Research On The Model Of Grid-integration Pv Station And Its Operation Characteristics

Energy crisis and environmental pollution have been extraordinary severe with the increasing consumption of fossil fuel. It is highly necessary to exploit and utilize renewable energy to decrease such crisis. In the utilization of various renewable energy, photovoltaic (PV) has been one of the widely used and increasingly developing meods to generate power all over the world. Moreover, for this power generation method, grid-integrated PV stations are highly focused and rapidly extended.On the basis of summarizing the PV development worldwide, research works on operation characteristics, and the basic principle of PV generation system, the purpose of this dissertation is to model large grid-integrated PV stations in Matlab/Simulink and a integrated power system simulation software DIgSILENT/PowerFactory, providing a platform to study and analyze the problems after large PV stations are integrated in the existing power system. The main works of this dissertation are as follows:(1) Study the modeling methods and the control methods for large grid-integrated PV stations. The focus for this study is the mathematic description of PV cells, inverter and the control of inverter in consideration of the existing power system. Simulation will be done based on the proposed model and control method. Characteristics and short current for the grid-integrated PV stations will be thus achieved.(2) Study the effect on reactive power and voltage for integrated large PV stations. Taking a practical PV station as an example, the effect of the PV station on reactive power and voltage is thoroughly investigated. In order to improve the static voltage stability, two solutions are suggested, i.e., installing reactive power compensation devices and controlling the output power of the inverters in PV stations.(3) Analyze PV station's effect on the transient stability of the small grid under different fault form, and put forward technique measures to improve the transient stability. By calculating a case, it is indicated that frequency controller can restrain frequency fluctuation after fault, and protection device of inverter can make PV stations connected to grid during fault, thereby, keep frequency stable, voltage source control mode can make voltage stable when motor starts.(4) Study PV station's impact on protection of urban power network. Study the impact on short current of system and then analyze the impact on protection of system and automatic reclosure.