Research On Reactive Voltage Control Strategy Of Distribution Network With Distributed Photovoltaic Source

Because the controllability and predictability of solar photovoltaic source is lower than that of traditional power source,the voltage fluctuation of the grid connected photovoltaic source will occur,which will reduce the power quality of the grid connected system and affect the safe and stable operation of the grid.Therefore,how to control the reactive power and voltage fluctuation of the photovoltaic grid connected system has become a research hotspot of scholars at home and abroad.Therefore,from the perspective of voltage fluctuation caused by distributed photovoltaic source connected to distribution network,this paper studies the control strategy of reactive power and voltage in grid connected system with distributed photovoltaic.Firstly,in order to solve the problem of voltage fluctuation caused by distributed photovoltaic source connected to the distribution network,the factors influencing reactive voltage of distributed photovoltaic grid connected system are studied,and the corresponding mathematical model of voltage before and after distributed photovoltaic source connected to the distribution network is established,which provides theoretical support for the follow-up control strategy research of photovoltaic inverter.Secondly,according to the single photovoltaic source in the distribution network,the photovoltaic inverter and reactive power compensation device are used to coordinate the voltage control of the distribution network,and the corresponding control model is established;Aiming at the situation of multiple photovoltaic sources in distribution network,the constant power control strategy of reactive power compensation device and photovoltaic inverter is used to coordinate the voltage control of distribution network,and the corresponding control process and model are established.Then,based on an existing constant reactive power control strategy of photovoltaic grid connected inverter,the mathematical model of three-phase two-stage photovoltaic grid connected inverter is studied,and the voltage quality problems faced by single and multiple distributed photovoltaic sources connected to the distribution network are comprehensively analyzed,The problem that the amplitude of line voltage may exceed the limit is solved.Finally,based on the constant reactive power control strategy,an improved is studied cosφ(P)The control strategy further ensures the voltage stability of the parallel point and improves the voltage quality quickly.Using PSCAD simulation platform to build constant reactive power control strategy and optimized cosφ(P)The feasibility and superiority of the control strategy are verified by changing the active and reactive power output of grid connected inverter.