Research On Optimal Scheduling Strategies For Multi-type Microgrids

Under the background of the goal of "double carbon" and the development of new power system,more and more large-scale distributed renewable energies,storage and new flexible loads are connected to distribution grids.However,the hosting capacity and absorption capacity of distributed new energy resources is constrained by radiation network structure and centralized scheduling management mode in traditional distribution networks.As an aggregation of distributed energy resources that effectively integrate distributed renewable energy,energy storage and different kinds of loads,microgrid provides effective support for distribution networks to adapt to large-scale distributed new energy access and consumption by virtue of its flexible and controllable and grid-friendly advantages.With the continuous improvement of the proportion of distributed new energy and the diversification of user-side demand,microgrids continue to upgrade in structure,technology and function,and are developing in the direction of direct fluidization,miniaturization,multi energy integration and clustering.New types of microgrids with various forms,such as DC microgrid with integrated wind,PV and storage,prosumers,and multi-energy microgrid integrating renewable energy,have been developed rapidly.Microgrids will become key components of the future distribution network,and the distribution network structure is expected to reshape and transform into a flexible and flat organizational structure.In this context,a series of new features,such as multi-micro grid interconnection and power exchange,two-way interaction between prosumers and distribution network,multi-energy coupling and complementary coordination,will increase the feasibility of distributed new energy consumption.At the same time,it brings new challenges to the scheduling and operation of microgrids.Traditional centralized scheduling strategies will be difficult to meet the flexible operation requirements of diversified microgrids.In order to new type microgrid flexible and efficient operation,novelty research on microgrids dispatching management is needed.In this thesis,the diversified form microgrid structures adapted to the consumption of high proportion distributed new energies are analyzed,and on this basis the optimal scheduling strategis of different types of microgrid systems,including multi-DC microgrid distributed dispatching,prosumers and microgrid interactive operation,and multi-energy microgrid coordination scheduling,are investigated intensively from the bottom level.The detailed work and main contributions are as follows(1)Distributed optimal scheduling of multi-DC microgrid system considering power interaction.With the rapid development of distributed solar PV,energy storage and DC loads,DC microgrid has obvious advantages than AC microgrid,and will usher in great development.Interactive and flexible operation of multi-DC microgrids will become an important mode of operation.In this thesis,an interconnection structure of DC microgrids based on the integrated mode of"distributed renewable energy+DC power supply+energy storage" is presented,and a distributed optimal scheduling strategy suitable for peer-to-peer power interaction among interconnected DC microgrids is proposed.The optimal scheduling model considers power interaction and energy storage power coordination among DC microgrids,and distributed model predictive control method(DMPC)is used for collaborative self-discipline scheduling of interconnected DC microgrids,so as to promote the efficient local absorption of distributed renewable energies by mining the complementarity of distributed wind power and PV in different microgrids and regulating the power exchange among DC microgrids,DC microgrids and distribution network.(2)Hierarchical coordinated and optimal dispatching of microgrid with multi prosumers aggregation integration.With the rapid development of distributed roof PV,electric vehicles and intelligent household appliances,a large number of prosumers will emerge in demand-side.Prosumers aggregation as a collective unit connected to the distribution network provides new means of flexible regulation for the safe and effective consumption of distributed PV power.In this thesis,a hierarchical architecture of microgrid with prosumers aggregation integration is proposed,and a hierarchical optimal dispatching model based on analytical target cascading(ATC)is established considering the adjustable potential of prosumers and active regulation resources of microgrid.The prosumers aggregation and micro grid are taken as different stakeholders for hierarchical optimal dispatching,the economy of interactive operation between prosumers aggregation and microgrid is solved through the decomposition and coordination between different subjects.The proposed strategy only needs the interaction of the boundary power information between the prosumers aggregation and microgrid,and the optimal operation solution can be obtained by parallel computing and alternating iteration between two layers.On the premise of effectively ensuring the privacy of prosumer,decentralized autonomy and coordinated scheduling of prosumers aggregation and microgrid is achieved.The rationality and effectiveness of the proposed scheduling strategy are verified by case studies.The proposed strategy provides a feasible new idea for effectively tapping the potential of demand-side regulation resources and promoting interaction between micro grid and prosumers.(3)Coordinated and optimal scheduling of multi-energy microgrid for renewable energy accommodation.Multi-energy microgrid is an important new carrier for locally distributed new energies accommodation,which improves consumption capacity of distributed renewable energies through the cooperation of multi-energy integration.At the same time,the development and application of integrated demand response(IDR)and energy storage systems provide new and effective measures enhancing the flexibility of multi-energy microgrid for high-proportion distributed new energies accommodation.In this thesis,a multi-energy microgrid optimal scheduling model is proposed,which systematically takes into account multiple energy conversion,multiple energy storage systems,IDR resources,and 100%consumption of distributed renewable energies,by optimizing and coordinating the flexible resources of different energy production,conversion,storage and consumption to realize the economic dispatching and operation of system.Furthermore,in order to evaluate hosting capacity of the developed multi-energy microgrid and increase consumption ratio of renewable energies,a scheduling strategy of multi-energy microgrid based on opportunity seeking information gap theory(IGDT)is proposed,which aims to provide an optimal scheduling scheme for multi-energy microgrid to accommodate more renewable energies without violating system operating limits.The simulation results show that under the premise of meeting the system security operation constraints,the proposed strategy generate feasible scheduling schemes which improve the local consumption of renewable energy and meet the economic expectation of system operation.The integrated demand response plays an important role in enhancing the flexible regulation ability and local consumption capacity of renewable energy in the multi-energy microgrid.The scheduling strategy provides a new idea to further promote the efficient consumption of high penetration distributed renewable energies in local multi-energy microgrid.