Research On The Maximum Penetration Level Of Multiple Distributed Photovoltaic System

With the development of photovoltaic power generation technology, more and more photovoltaic power is connected into the distribution network, which bring bad influence to the stable operation of the distribution network. When the PV power system input too many power distribution network, it will lead to the distribution of the feeder voltage. In order to prevent the feeder over-voltage, to coordinate the grid-connected power of photovoltaic power generation system becomes the urgent problem.This paper starts from the aspect of photovoltaic power generation system, carries on the elaboration to the photovoltaic power generation system, including the topological structure of the system, the maximum power point tracking(MPPT) technology, grid connected inverter and islanding detection technology key technology. Among them, the MPPT technology related to the output power of the photovoltaic power generation system, but conventional MPPT technique cannot accurate track the global maximum power under the condition of shade and simulated annealing particle swarm optimization algorithm can accurately track the global optimum. This paper applies the simulated annealing particle algorithm to the MPPT technology, for the global maximum power point tracking can avoid tracing to fall into the local optimum. Next, the effect of system access to the distribution network is considered in this paper. Through analyzing the change of voltage of the distribution network in the access before the photovoltaic power generation system and the after at the point of view of voltage dropping, draw the conclusion that after the connection of the photovoltaic generation system, the feeder voltage and the output of photovoltaic generation system is directly related in the distribution network. Hence, the active power reduction mechanism is used to prevent the feeder voltage limitation in this paper. Then, the sensitivity of the change of the feeder voltage and the photovoltaic system active power is studied, which makes the feeder voltage deviation exceeding a set threshold to use feeder voltage sensitivity matrix calculating the quantity of active power cuts. After that, adjust the control strategy of grid connected inverter and realize active power reduction. So as to ensure the feeder voltage under limitation to export active power to distribution network as much as possible.In order to verify the feasibility and accuracy of the proposed control method in this paper, the proposed control method is applied to the actual examples, and the case results are analyzed. We draw that the control method can effectively solve the injection of photovoltaicgeneration system causing feeder voltage exceeding limitation. Also it can improve the economy of photovoltaic generation system.