Distribution Network Optimization For Distributed Energy Access

Large scale centralized power supply is more and more difficult to meet the increasing requirements of power supply quality and safety and reliability.Distributed energy can alleviate the hidden dangers of large-scale centralized power supply.At present,a large number of distributed energy has been connected to the distribution network.Among the many distributed energy sources,the grid connection and utilization of distributed photovoltaic is an important way to deal with the current energy and environmental crisis.High proportion of distributed photovoltaic access may affect the safe operation of distribution network and restrict the ability of distribution network to accept distributed photovoltaic.In view of the voltage over limit problem caused by high proportion distributed photovoltaic access,the paper analyzes the acceptance capacity of distribution network to distributed photovoltaic,puts forward the promotion strategy of acceptance capacity,and studies the voltage regulation of distribution network by using distributed energy in distribution network.In the acceptance capacity analysis,the cooperation of multi-voltage distribution network is considered.The voltage regulation of medium voltage distribution network and transformer tap which has certain regulation ability after a large amount of distributed energy is connected is reasonably utilized.The lack of voltage regulation means of low-voltage distribution network is alleviated through the mutual influence of medium and low voltage distribution network,and the ability of low-voltage distribution network to accept distributed photovoltaic is improved.The optimal operation model of 10kV MV active distribution network and the model of location and capacity determination of 380V distributed photovoltaic distribution network are established.The simulation results verify the effect of the proposed method on the acceptance capacity.The influence of distributed photovoltaic access and voltage regulation on the voltage distribution of the MV active distribution network is analyzed,and the influence of different load on the acceptance of distributed photovoltaic and voltage regulation mode is also analyzed.When the access of distributed photovoltaic in distribution network exceeds its acceptance capacity,four strategies to improve the acceptance capacity of distribution network are proposed,including the transformation strategy of distribution network for replacing distribution network lines and on-load voltage regulating transformers,and new equipment access strategy for connecting energy storage and adding communication equipment to distributed photovoltaic inverter.The feasibility and pressure regulating ability of the four strategies are analyzed,and the economic selection of the four strategies is compared.The voltage regulation strategy of distribution network after high proportion distributed photovoltaic access is studied.The distributed energy in distribution network is aggregated into virtual power plant based on the voltage regulation strategy of time-sharing price.The virtual power plant operates optimally with economy.Energy storage and transferable load respond to time of use price to alleviate voltage rise in distribution network.If the voltage is not satisfied,the distributed photovoltaic inverter is adjusted,and the inverter voltage regulation model with the minimum reactive power absorbed by inverter is constructed The optimal voltage regulation model of energy storage and distributed photovoltaic inverter is established without considering the influence of time-sharing price,and the coordinated voltage regulation strategy between energy storage and inverter is obtained.