| The extensive use of wind,light,and energy storage technologies,as well as the popularity of distributed new energy and electric car charging stations,has made the operation and administration of AC distribution grids a tremendous problem.Flexible DC distribution systems feature a long supply radius,huge transmission capacity,no harmonics,excellent power quality,low reactive power loss and skin effect,high power transmission efficiency,and easy access to new energy sources when compared to AC distribution networks.Furthermore,DC distribution systems are simple to connect and feed into various places.As the technological issues of DC voltage transformation have been solved,academics and industry have begun to focus more on research into grid-like multi-terminal DC distribution networks.Translated with www.Deep L.com/Translator（free version）Normal point-to-point DC systems can be tide-controlled easily via converter stations,but reticulated multi-terminated DC distribution systems frequently have multiple DC feeder circuits on a single converter station bus,making tide-control and regulation on DC lines impossible to achieve solely through converter station DC voltage or power control.That is,when the number of connected feeds exceeds or equals the number of converter stations,full power flow management is not possible.The tidal will be spread naturally according to the line impedance in this instance,which could result in larger power losses and even overloads.Therefore,DC current controllers need to be introduced to achieve effective control of line currents in DC systems.The mainstream DC current controllers are of the variable voltage type series type,while the current mainstream DC current controllers face problems such as small tidal regulation range,non-expandable ports and insufficient structural modularity.This paper conducts a study on the proposed embedded DC current controller structure,operation control and its application in the field of medium voltage distribution.The main work is as follows.1.In conjunction with an input series output parallel DC transformer design,a multi-port inline DC current controller is presented.It offers flexible tide control in a networked multi-terminal DC distribution system with numerous DC ports of the same voltage level and a completely controlled voltage difference between the DC ports.The DC current controller is self-balancing and features a modular topology,easy multi-port extension,bi-directional line current adjustment,and a wide current adjustment range.2.An energy balancing cooperative control strategy for the embedded DC controller and the DC transformer is proposed,which allows for energy interaction and cooperative operation of the two to maintain the embedded DC transformer’s constant DC bus voltage while ensuring the input series output parallel DC transformer’s normal operation.A simulation model is created in MATLAB/Simulink to validate the feasibility and effectiveness of the proposed DC tidal current controller and the proposed control scheme.3.An optimized control approach for a multi-port DC controller integrated in an input series output shunt DC transformer is given based on the energy balancing cooperative control technique,which decreases losses and enhances the equipment’s operating efficiency.Simulation results show the proposed DC tidal current controller and the proposed optimal control scheme are feasibile and effective.4.A low-power experimental prototype was built on the power electronics building block experimental platform to verify the feasibility and effectiveness of the proposed embedded DC current controller topology,as well as the proposed energy cooperative control strategy and optimal control strategy. |
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