Research On The Capacity Of Distributed PV Power Supply Calculation And Reactive Power Voltage Control Strategy

Basing on the background of global economic development,power generation technologies that use renewable energy such as solar energy have reduced environmental pollution on the premise of ensuring rapid economic development,and are gradually becoming the focus of research in various countries.Due to the access of distributed photovoltaic power sources,the single-powered passive distribution network becomes an active distribution network with multi-segment power supply,and the power appears in two-way or even multi-directional flow,and with the increase in the number of distributed photovoltaic power supplies,The power grid trend has become more complicated.The location,quantity and output of the distributed photovoltaic power grid will affect the power flow of the distribution network,causing the fluctuation of the node voltage,causing the voltage of some nodes to rise or even exceed the limit.A certain degree of impact on the operational requirements of the power system "safe,stable,and economical".Therefore,it is important to study the voltage control method of grid-connected photovoltaic power supply for the operation of power systems.Firstly,this paper studies the voltage distribution and power loss principle of the traditional distribution network and the voltage variation mechanism of the distribution network after the distributed photovoltaic power supply is connected.Using PSASP software to set up a 10kV line model,and study its influence on the node voltage from the perspective of different access locations and capacities of distributed photovoltaic power sources,load distribution and size of distribution network,etc.And provide measures to improve voltage quality from the perspective of distribution network and distributed photovoltaic power supply.Secondly,The problem of voltage over-limit caused by distributed photovoltaic power supply accessing the distribution network.The objective function is to maximize the access capacity of distributed photovoltaic power supply that can be accommodated in the distribution network.The voltage deviation of the node is within the specified allowable range,the photovoltaic capacity limit and the power flow are the constraints.The calculation of PV access capacity is realized by using genetic algorithm in MATLAB platform.It is applied to a lOkV line in Hunan Province for distributed access capacity calculation.The simulation results prove the rationality of the model.Finally,Making full use of the reactive power output characteristics of the inverter,the Q(U,P)reactive power control strategy is proposed.The core idea is to adjust the voltage to the allowable range and the total reactive power output of the inverter is at a minimum.At the same time,the active and reactive power integrated control scheme is proposed for coordinated voltage control.The integrated control scheme can reduce unnecessary access capacity reduction and achieve as much photovoltaic output as possible within the inverter output reactive voltage range.Combined with a lOkV line example in Hunan,the simulation results prove the effectiveness of the scheme.This paper provides a solution to the problem that the distributed photovoltaic power supply enters the distribution network and causes the node voltage to exceed the limit.