Research On The Influence Of Grid-connected Photovoltaic System On Power Grid

With the rapid development of economy in recent years,people's living standards are improving day by day.With the increasing energy consumption,the quality of life also puts forward higher requirements for environmental protection.Solar energy is the most common and clean renewable energy in the world.Because of the development of energy,it has been widely used in our daily life.Photovoltaic grid connected power generation technology takes into account the needs of both economic development and environmental protection,and is one of the effective means to realize the development of low-carbon economy.With more and more photovoltaic grid connected power generation system connected to the distribution network,its impact on the distribution network has gradually developed into a variable that is not ignored.In order to ensure the safe and stable operation of the distribution network and the safety of power customers,it is very important to study the influencing factors and consequences of the photovoltaic grid connected power generation system on the distribution network,so as to grasp the law.Photovoltaic grid connected power generation has caused the change of traditional distribution network structure.The change of network structure is accompanied by the uncertainty of photovoltaic power generation power capacity,output situation and grid connection position,which further results in the change of distribution network voltage distribution,short-circuit current and power flow direction.The original reliable state or change is full of uncertainty,accompanied by photovoltaic power generation access,The emergence of islanding effect is inevitable,and the distribution network integrated with photovoltaic power becomes more complex.In this paper,the photovoltaic grid connected power generation system model,islanding effect,distribution network voltage and relay protection are studied.Firstly,the photovoltaic array,maximum power tracking technology and inverter control strategy of photovoltaic grid connected power generation system are studied.The simulation model of related modules and photovoltaic grid connected power generation system is constructed by MATLAB,the model is verified to be feasible.Secondly,introducing the active islanding detection method and passive islanding detection method to analyze the islanding effect,and compares their advantages and disadvantages.Based on the model of photovoltaic grid connected power generation system,the influence of the system on the distribution network under the condition of island operation is simulated and analyzed.Then,through the test of IEEE 13 node distribution system,combined with the output of photovoltaic grid connected power generation system and the location of access to the distribution network,it is analyzed that the greater the total output of the photovoltaic grid connected power generation system is,the closer the connection position is to the end of the distribution network,and the more obvious the supporting role of the overall voltage of the distribution network system is.Finally,the influence of different access locations and different access capacities on the relay protection of the grid connected distribution network is studied.After connecting to the distribution network,the protection devices at different positions and the fault points at different positions receive different effects.There are problems such as protection devices not affected,expanding or shortening the protection range and misoperation.