| The world's energy shortage has become increasingly prominent,the problem of environmental pollution is increasingly serious,with new energy power generation based on micro-grid technology more and more people receive the welcome.So far,although the exchange of micro-network technology has made some progress,but its complex structure,energy conversion process power loss and other shortcomings can not be ignored.DC micro-grid technology in the current research has been a certain application,but its limitations are more difficult to overcome.Based on the above two considerations,this paper studies the AC and DC mixed micro-grid,which combines the advantages of AC micro-grid and DC micro-grid,with a variety of AC and DC clean energy and emerging DC compatible with inclusive and flexible topological features.It is the main research content of this paper to explore the hybrid switching control law of AC micro-grid and DC micro-grid interconnection..It considers the DC bus voltage deviation,micro-grid power shortage,the battery charge status and other factorsThis paper in-depth analysis of a variety of microsource grid converter topologies and multiple operating modes,which includes Wind power generation system access converter topology and its operation mode control,PV micro-source system access converter topologies and operation mode control,energy storage unit bidirectional DC-DC converter topologies and operation mode control and its operation mode control.It analysis the power converter topology and operating modes and control strategies,and improves it.Then,the AC-DC micro-grid hybrid switching model,PV hybrid operating mode switching modeling,wind power operating mode hybrid switching modeling,the hybrid energy storage system operating mode hybrid switching modeling,the main grid hybrid switching modeling,and micro-source converter hybrid switching modeling are established.Articles in-depth took analysis the operational control law of AC micro-grid and DC micro-grid in islanding mode and grid-tied mode.Then by the definition of AC-DC micro-grid events and switching condition,Chapter II introduced hybrid switching model,it completed the design of hybrid automatic machine controller.Hybrid control system includes:AC-DC micro-grid operation mode control,operation control unit photovoltaic,wind power unit operation control,battery energy storage unit operational control,DC/AC power converter bi-run control,load control,five big run the control unit.Taking it into account that a variety of conditions and failure process that may arise in simulation.A coordinated control energy control strategy based on the DC bus voltage and micro-grid power shortage was proposed.This paper discusses the structure of AC/DC hybrid micro-grids with sub-bus,and then divides the switching system of AC-DC micro-grid into three levels:topology switching layer,micro-source/load unit The switching mode of the running mode and the internal switching layer of the power device interface are used to construct the corresponding model for the three different switching layers.The three switching layers are analyzed one by one,and the energy optimization strategy in the AC/DC micro-grid is proposed.And the simulation experiment is designed based on the model built on the hierarchical control structure of the switching system.According to the results of the experiment,it is concluded that the mixed stratified control method proposed in this paper can adapt to the problem of wind speed and direction change of wind power source in the face of the instability of micro-source sunlight,The switching of different operating modes in the hybrid micro-grid can play a very good coordinating role.As far as possible,the topology of the micro-grid can be simplified as much as possible.Under the premise of ensuring the power balance,the system is more stable and the operation control is more convenient Efficient.At the end of this paper,this study is a comprehensive summary,and then the direction of future research to do a preliminary idea. |
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