Research On Voltage Regulation Of PCC And BESS Capacity Planning Of Distributed Photovoltaic Power Generation System

The world's energy structure will continue to undergo new changes.Traditional energy reserves are limited,and traditional fossil fuels bring serious pollution to the natural environment on which human beings depend.Solar energy is inexhaustible for its natural advantages.Moreover,environmental protection and pollution-free have become a reliable new energy source to solve the energy crisis.Photovoltaic power generation meets the needs of this development.The growing demand for new energy also accelerates the development of PV technology.The instability of photovoltaic output and the unpredictability of the load lead to photovoltaic access to the distribution network to lead to power flow reversal,which may cause voltage fluctuation or even exceed the limit of photovoltaic parallel network,thereby affecting the user's power quality and even equipment failure.One of the important reasons for development.In low-voltage distribution networks,this problem is even more serious.High power density and high charge discharge rate is the characteristics of BESS,and environmental protection without pollution.It plays an increasingly important role in the field of distributed photovoltaic grid-connected power with functions such as power stabilization and voltage adjustment.Due to the instability of photovoltaic output,the BESS can emit a large current of several amps or even tens of amps for charging and discharging,and Charge and discharge process can be completed within several tens of seconds to minutes.It is precisely because of these unique advantages that it can be applied in distributed photovoltaic grid-connected systems,as a very important device in the system.At present,the price of the battery is still expensive,Improper allocation of BESS capacity will affect the performance and allocation benefit of the energy storage system.The research content of this paper is the dynamic regulation control strategy of photovoltaic parallel grid voltage with the participation of Bess and inverter,and the optimal configuration of Bess capacity based on photovoltaic parallel grid voltage regulation.The following is the specific work content.1?Analyze mathematical models and circuit models of photovoltaic energy storage grid-connected systems and build simulation models,including circuit models and simulation models of photovoltaic cells,energy storage circuit models,photovoltaic inverter circuit models,and photovoltaic inverter control models and simulations.The model and simulation model of BESS bidirectional DC/DC converter,and finally the photovoltaic MPPT simulation model is established,And The analysis result indicate that the simulation Built model is effective.2?Regarding the design of grid-connected point voltage regulation schemes involving energy storage,a grid-connected point voltage control strategy based on active-reactive control was proposed.The control strategy mainly consists of three parts.One is When is the voltage regulation signal sent out.When the voltage exceeds the limit,the battery charge and discharge instructions are issued.The second is the control of bi-directional DC/DC converter in energy storage system.The goal of bidirectional DC/DC converter is designed with the voltage of parallel node as the control quantity.It controls the active power to adjust the grid-connected point voltage.The third is the control of the photovoltaic inverter.The photovoltaic inverter uses the remaining reactive power to perform grid-connected point voltage control.Finally,in MATLAB/SIMULINK,the photovoltaic energy storage grid-connected model simulation circuit model was established according to the general control schematic diagram of the system,and the voltage control effect of the control strategy was verified under two weather conditions.3?In terms of capacity optimization of energy storage systems,and proposed a network based on a photovoltaic energy storage capacity of configure voltage regulation.Based on the selection of the lithium-ion battery as the BESS of the PV,the BESS capacity is optimized.Paper proposes a photovoltaic grid-connected point voltage adjustment control strategy using limited capacity energy storage.In order to adjust the voltage of photovoltaic parallel network point to be stable within the required range,provide control strategy support for the configuration of capacity in the medium and low voltage distribution network.Then,considering the mutual constraint relationship between the energy storage SOC and the energy storage allocation capacity,The mathematical model aims at minimum initial investment.And optimize the energy storage capacity of the configuration and power is achieved with the minimum initial investment as the optimization goal.Then use particle swarm optimization to iteratively solve the optimization model and verify voltage control strategies in the effectiveness of a PV plant.