Optimization Of Power Grid Dispatching Based On Three-layer SoS Equilibrium Model

With the development of active distribution networks,the layout of the modern power system is increasingly decentralized.On the one hand,active distribution networks emphasize the two-direction interaction with the traditional power system.In recent years,the variety of distributed energy has been increasing.Except for traditional fossil energy sources,renewable energy such as photovoltaic energy and wind power has also been emerging.At the same time,distributed clean power,mainly supported by renewable energy,has also developed rapidly because of its environmental friendliness,while distributed power generation relying on fossil energy has been developing slowly.When these distributed power sources participate in supplying electricity in active distribution networks,it is necessary to make fundamental and structural adjustments to the current power dispatch mode on whatever the generating schedule or on the on-grid price policy,thus making the distributed power sources fit with the modern power system.On the other hand,due to the big amount of distributed power generation in active distribution networks,there will be greater uncertainty in the whole system than before,which makes it more challenging to ensure safety and stability of a large system.Meanwhile,as an important part of the future active distribution network,electric vehicles have developed rapidly in recent years,and its penetration rate has been increasing year by year.The rapid growth of electric vehicles has made it increasingly important to optimize the dispatching of power systems that contain electric vehicles.The electric vehicle’s battery-changing mode has been widely recognized as the most promising dispatching mode of electric vehicles.Therefore,in addition to the traditional generating units in active distribution networks,this thesis selects battery-changing stations as the main research targets that participate in power dispatching.Aiming at the distributed and hierarchical network topology,this thesis proposed a three-layer distributed hierarchical equilibrium algorithm for optimal scheduling considering battery-changing stations based on the system of systems(SoS)theory instead of the traditional centralized optimization.This algorithm is more suitable for the modern power system,which is increasingly distributed.In the process of the proposed distributed optimization,each subsystem only calculates its own optimization objective function and can only obtain a little optimization information of other participants,so the final optimization results may make the power flow of some lines exceed the limit.For the line congestion problem that may occur in the optimization,a dynamic constraint set method is introduced in this thesis to examine and correct the optimization results.The V2G(vehicle-to-grid)scheduling and the operating cost of the electric vehicle stations are closely related to the charging and discharging price.This thesis analyzed the relationship of charging and discharging price between electric vehicle stations and proposed a logarithmic V2 G price guidance model and a price sensitivity matrix based V2 G model,which are both supposed to play a guiding role in the V2 G behavior of electric vehicle stations and bring considerable economic benefits.The feasibility and effectiveness of the multi-level optimization model,line congestion diagnosis and correction model and V2 G price guidance model have been tested and verified through different cases of a 15-node test system in different chapters.