Research On Local Voltage Control Strategy Of Distribution Network Using Residual Capacity Of Photovoltaic Inverter

The rapid development and application of distributed photovoltaic power sources have brought many power quality problems to the distribution network while alleviating energy crisis and environmental problems.Among them,the voltage over-limit problem is the main reason for limiting the further large-scale development of distributed photovoltaic.Considering that there is a large resicdual capacity in most of the PV inverter operation process,this paper aims to use this residual capacity to provide reactive power support for the distribution network and solve the voltage limit problem of the distribution network.The mathematical model of distribution network with distributed photovoltaic power is established,and the influence of single point access and distributed access active power output of distributed photovoltaic power on the distribution network's voltage distribution of feeders is deduced.On this basis,the influence of photovoltaic power output reactive power on voltage is analyzed,which provides a theoretical basis for improving the voltage quality of distribution network by using PV inverter remaining capacity.The sensitivity of local voltage to photovoltaic active power and reactive power is analyzed.A local voltage control strategy of over-voltage reactive power priority and under-voltage active power priority is proposed based on the control model of photo.voltaic gid-connected inverters.On this basis,looking forward to the future development of distribution network,a feeder voltage optimization coordination control strategy for multi-inverters that only collects electrical parameters of each power node is proposed.The strategy can call the remaining capacity of the whole network inverter,to achieve the voltage optimization goal,The strategies were simulated and verified by given different working conditions.A local voltage controller was designed and developed for the existing distributed power in the distribution network.Firstly,the controller detects the parameters of grid-connected voltage and grid-connected current of the inverter in real time.Secondly,the reactive power required to adjust the voltage to the qualified range is calculated,and determines whether it is necessary to reduce the active power output.Finally,the reactive power and active power instructions are sent to the grid-connected inverter through the RS-485 communication interface,and the inverter outputs corresponding active and reactive power according to the command to achieve the purpose of adjusting the voltage quality of the distribution network.The correctness and effectiveness of the developed local voltage controller and the proposed local voltage control are verified by experiments.