Voltage Regulation Control Strategy And Siting And Sizing Of Distributed Energy Storage Considering Coordination Among Clusters In Distribution Network

As the country further promotes the reform of the energy system and builds a new power system,the proportion of distributed power in the power grid is increasing.In recent years,policies have strongly supported the introduction of distributed photovoltaics in the distribution network.The penetration rate of distributed photovoltaics in the distribution network has significantly increased year by year.Its distribution has also brought a series of problems while reducing the use of fossil energy.Distributed photovoltaic is constrained by its own characteristics.In addition to the regular power generation time every day,its disorder and contingency affected by weather,temperature and other factors put forward higher requirements for the safe and stable operation of distribution network.Moreover,the high permeability of distributed photovoltaics in the distribution network leads to power reversal to the upper grid during the peak period of power generation,which also affects the node voltage.Distributed energy storage has the ability of fast power response and certain storage of electric energy.It is suitable for adjusting distributed photovoltaic to cause a series of problems in the distribution network,and its application in the distribution network has gradually become large-scale.This paper first introduces the concept of cluster partition suitable for distribution network and the principles and indicators of cluster partition,and explains the purpose of cluster partition through the schematic diagram of distribution network cluster partition structure.By using the improved modular index to divide the distribution network and using the sensitivity index as the parameter,the relationship between power and voltage in the sensitivity index matrix is discussed in detail.The distribution network cluster partition model is established,and the system is divided according to the improved modularity index.By dividing the distribution network into clusters,energy storage resources can be allocated more effectively.Then,aiming at the problem of node voltage exceeding the limit caused by distributed photovoltaic high permeability access to distribution network,an energy storage voltage regulation control strategy based on cluster partition is proposed.The strategy is based on the previous cluster partition.Under the premise of considering the energy storage power and state of charge,the mathematical model of energy storage optimization voltage regulation is constructed.According to the total power required by the cluster where the node exceeds the limit voltage,the energy storage in the cluster is allocated to determine the energy storage timing action power when the distributed energy storage operation income is the largest.The voltage fluctuation,distribution network loss and energy storage operation economy under different schemes are analyzed.The comparison between the two schemes shows that the corresponding scheme of the proposed strategy not only effectively controls the node voltage,but also achieves good economy.Finally,aiming at the problem of siting and sizing selection when energy storage is configured in distribution network,a two-layer optimization strategy of distributed energy storage siting and sizing selection based on cluster planning is proposed.Based on the results of cluster division,a two-layer coordinated siting and sizing model of distributed energy storage is established.The upper-layer planning takes the clusters as the basic unit and the minimum net cost as the goal to plan the energy storage capacity and power connected to each cluster.The lower-layer planning takes the nodes in the clusters as the basic unit,and the minimum transmission network loss between the distribution system and the cluster as the goal,and optimizes the access siting of each node energy storage in the cluster.For this model,the two layers are target quantities and variables,which are solved by cyclic iteration.The simulation results show that the energy storage configuration of the proposed scheme can achieve the node voltage not exceeding the limit,reduce the system network loss,and improve the economy of energy storage configuration.