Research On Energy Management And Coordination Control Strategy Of Multi-connected Microgrids Based On Ring Network Architecture

With the increasing of distributed generation,microgrid,as one of the effective ways to connect distributed power,has been developed rapidly.However,with the increasing permeability of intermittent renewable energy,such as photovoltaic,wind power and so on,the stability of microgrid system is reduced.At the same time,the scale of microgrid is gradually increasing,which makes the dispatching of distribution network more complex.Therefore,a number of microgrids in a certain region will be interconnected to form a community,to achieve a larger scale of renewable energy consumption,improve operational stability,and reduce the cost of electricity purchase.How to realize the economic regulation of multi-connected microgrids and the optimal power flow distribution of regional distribution network system has become an urgent problem to be solved.Therefore,the energy management and optimal control strategy of multi-connected microgrid based on ring network architecture are studied in this dissertation,and the main research contents are as follows:The configuration method of composite energy storage for multi-connected microgrid based on ring network architecture is studied.Firstly,the operation architecture of multi-connected microgrid ring network is studied,and the power flow balance of each microgrid node is achieved through the tie-line interconnection under this architecture.Secondly,considering the order of information exchange between microgrids,the hierarchical energy management model of multi-connected microgrid is studied,and the global optimization problem is decomposed to meet the needs of hierarchical optimization.Finally,the influence of the lifetime loss of the energy storage system on the dispatching accuracy of the multi-connected microgrid,the safety margin of the preset state of charge in the composite energy storage configuration,and the rapid response to the power fluctuation of the grid-connected node are fully considered,and the peak shaving and valley filling are realized.It provides a guarantee for the stability of multi-connected microgrid.In this dissertation,the day-ahead control strategy of multi-connected microgrid based on ring network architecture is studied.Firstly,in order to minimize the total life cycle cost of multi-connected microgrid,a delamination regulation model is established.Secondly,the Lagrange multiplier is added to transform the life-cycle cost model into the marginal cost model,which takes into account the balance of power flow and the steady-state security constraints in the system,and uses synchronous coordinated control to control the multi-connected microgrid.Finally,based on the improved Benders decomposition algorithm,the global economic regulation and control calculation of multi-connected microgrid is carried out to ensure the privacy of data and the independence of decision making under the condition of data privacy and decision-making independence,aiming at the problem of hierarchical calculation of multi-connected microgrid regulation and control in recent days.The control accuracy of multi-connected microgrid is realized.In this dissertation,a rolling intra-day control strategy for multi-connected microgrid based on composite energy storage is studied.Firstly,in order to improve the scheduling error,considering the power balance and steady-state security constraints of the multi-connected microgrid system,a multi-connected microgrid intra-day hierarchical regulation model is established.Secondly,in order to further improve the service life of the energy storage system and add the cost penalty factor of inadequate capacity allocation,the lower layer control method based on the robust adaptive characteristic is studied,and the cost model of the energy storage system for correcting the output of the distributed power supply is established.In this dissertation,asynchronous coordinated control is used to carry out the rolling correction of multi-connected microgrid in the day.Finally,the Benders decomposition algorithm is used to solve the intra-day regulation,determine the power transmission characteristics,the error of the multi-connected microgrid's day-ahead regulation is corrected,and the accuracy of multi-connected microgrid in intra-day control has is improved.The application of energy management method in multi-connected microgrids is analyzed.Firstly,the ring network architecture is applied to the demonstration project.Considering the lifetime and stabilization characteristics of the energy storage system,the capacity configuration of the composite energy storage system is modified based on the state of charge safety margin.Secondly,the characteristics of power exchange among microgrids and between microgrid and distribution network under different architecture modes are analyzed,and the benefits of multi-connected microgrids under ring network architecture operation mode are compared.Finally,relying on the demonstration project,the proposed stratified energy management method,day-ahead regulation and intra-day rolling correction control methods are adapted to the grid dispatching requirements,and the renewable energy consumption is improved to ensure the reliability of power supply.