Research And Design Of Photovoltaic Access For Three Phase Imbalance In Low Voltage Power Grid

With the continuous improvement of the economic level of our country,the demand and demand quality of electricity is increasing.A large number of single-phase load and nonlinear impact load are connected to the power grid.Their operation further aggravates the phenomena of voltage fluctuation,flicker,unbalanced three-phase and so on,and seriously threatens the safe and stable operation of the power grid.At present,aiming at the unbalanced load three phase problem of the low voltage distribution network,the domestic and foreign measures are mainly carried out through the following three methods: the load is balanced in phase sequence,the distribution network is restructured and the load is compensated.Each method has a corresponding problem.With the rapid development of power electronics technology in China,the technology to solve the three-phase load imbalance of distribution network is also constantly updated.At present,the operation status of distribution network can be monitored in real time.Through the commutation device and commutation switch to adjust the load imbalance of distribution network terminal,the problem of three-phase load imbalance of distribution network can be solved quickly.The power-off time of the method is less than 20 ms in engineering,and the requirement of most electric equipment for power quality can be met.With the growing maturity of grid connected photovoltaic technology,photovoltaic power generation can not only alleviate the problem of energy shortage,but also solve the problem of low terminal voltage caused by three-phase imbalance in distribution network based on its flexible characteristics.In this paper,according to the working principle of the three-phase unbalance automatic adjustment device of the distribution network,the problem of three-phase unbalance in the distribution network is solved by considering the grid connected with the photovoltaic power generation.The distribution terminal analyzes the components of PV module and the distribution network according to the real-time measured data of the measurement device,and controls the PV module's grid connection through the automatic commutation switch.First of all,the design principle diagram of grid connected photovoltaic power and automatic load adjusting device combination;then,through MATLAB/SIMULINK simulation,the principle diagram of the designed simulation.According to the potential problems of PV grid connection,a monitoring and protection circuit is designed.Finally,according to the simulation chart,the experimental device is set up to solve the three-phase unbalanced problem of the distribution network.The experimental research is carried out,and the purpose of combining the photovoltaic grid with the load automatic adjustment device to control the unbalanced three-phase power grid is achieved.