Study On The Impact Of Photovoltaic Grid-connected Power Generation System On Power Grid Operation And Its Countermeasures

Energy and environmental crisis has become an important issue affecting the sustainable development of mankind.Photovoltaic power generation has attracted more and more attention due to its pollution-free and renewable characteristics,and the photovoltaic power generation industry has developed rapidly.However,the random fluctuation characteristics of photovoltaic power generation itself will pose a serious threat to the safe and stable operation of the power grid.Meanwhile,with the continuous construction of photovoltaic power stations and the continuous improvement of the volume of single photovoltaic power stations,the influence of photovoltaic power stations on the operation of the traditional distribution network is also increasing,For example,power flow,line loss,voltage distribution and relay protection configuration of the distribution network all face great challenges.Therefore,this paper studies the impact of distributed photovoltaic on the power grid and its countermeasures after grid connection,and attempts to solve or mitigate the impact of distributed photovoltaic on the power grid after grid connection.The main research work is as follows:1)This paper established the photovoltaic power generation system,the mathematical model of each part,and make the necessary assumptions and simplified form the mathematical model,and applied this model in PSASP user center set up the whole pv system,simulation results show that the optical interference and under the disturbance of three phase short circuit,the electromagnetic transient model and electromechanical transient model of transient response characteristics are very similar,and shows the feasibility of the model and the rationality of the model and hypothesis.2)Next,the influence of grid-connected photovoltaic power positioning and grid-connected capacity on voltage fluctuation,voltage distribution and power flow of the distribution network after the distributed photovoltaic power generation system is integrated into the distribution network is studied.The results show that distributed photovoltaic power generation has an unavoidable impact on the existing distribution network structure,resulting in multi-source distribution network and complicated power flow direction.In order to reduce the impact,active power should be output as much as possible,and reactive power should be reduced,so that the whole system can work at the best power and state.3)Then,the influence of distributed photovoltaic grid-connection on relay protection characteristics is studied,and the solution is proposed.Combined with the grid-connection example of 66 kV photovoltaic power station,the specific operation method of resetting distribution system and relay protection device is expounded.4)Finally,taking A photovoltaic power station established in A district of Inner Mongolia(longitude 98.46,latitude 36.9)as an example,the simulation software data were compared with the actual data of the project,and it was found that the access point capacity and operation mode had the same influence on the power flow voltage distribution of the system.