Research On The Distributed Photovoltaic Absorptive Capacity Of Active Distribution Network Based On Voltage Quality

In recent years,a large number of distributed photovoltaic power generation systems are incorporated into the distribution network,which makes the structure of the distribution network more complex.When the distribution network contains distributed power,the power flow in the distribution network is no longer single,that is to say,it changes the trend of the traditional distribution network.Because of the access of distributed power,the power flow becomes a two-way distribution system,which becomes an active distribution network system Unification.With the increasing penetration of distributed photovoltaic in the active distribution network,the impact of power flow distribution on the voltage quality of the distribution network will become increasingly prominent,and even threaten the safe operation of the grid.Therefore,it is very necessary to study the distributed photovoltaic absorption capacity of the active distribution network to meet the voltage quality.Firstly,the distributed photovoltaic power generation system is analyzed theoretically,and the mathematical models of photovoltaic cell,photovoltaic array and inverter are established.MPPT control strategy is used to control the stability of distributed photovoltaic power generation system.The simulation model of photovoltaic cell,photovoltaic array,inverter and control algorithm is built by PSCAD / EMTDC simulation software,and a set of simulation model of distributed photovoltaic power generation system based on electromagnetic transient in PSCAD / EMTDC environment is established.The simulation model of photovoltaic array and bipolar photovoltaic power generation system is built by using the simulation model,and the simulation model is verified by the change of waveform Accuracy..Secondly,this paper theoretically analyzes the voltage quality impact of the distributed photovoltaic access active distribution network,including the impact of the distributed power flow on the grid voltage deviation,voltage fluctuation,harmonic and three-phase imbalance,and the impact of the distributed access power flow on the voltage quality is verified by simulation.Thirdly,the main factors that affect the distributed absorption are analyzed,including line length,impedance characteristics and load properties.At the same time,by using PSCAD / EMTDC simulation software to analyze four scenarios of Chaoyang jinzhangzi substation,it is concluded that the impact of access location and access capacity on the voltage quality of active distribution network is more prominent,which fully verifies the analysis results.Finally,a three-phase power flow calculation method based on node current injection is proposed.This method takes the optimization of multiple voltage quality indicators as constraints,and can provide the distributed photovoltaic absorption capacity that meets the national standard limit.The accuracy and practicability of the model are verified through the analysis of IEEE-33 node system and an example,which provides a reference for photovoltaic enterprises to submit grid connection application.