Research On Key Technology Of Monopolar-to-Bipolar Converter Used In DC Power System

With the increase of human energy demand,fossile energy will enentually dry up.We must develop the new way to explore resources.As the advantages of inexhaustible,clean and pro-environment of solar energy and wind energy,making them the focus of human development and utilization.At present,most of the electrical equipment need to converte AC into DC to use.If we direcialy use the form of direct current to transmiss power into user.Then we can remove the AC-DC link conversion to improve transmission efficiency.With the development of power electronics technology,HVDC has once again become the focus of attention after a century of silence.Therefore,researching the power supply form of DC buildings and constructing DC micro-network architecture has a broad background.DC micro-grid bipolar operation can provide a variety of voltage level to meet the different load requirements.In the DC grid,the DC output power of renewable energy generation station is featured with both the randomness and fluctuation.Since the monopolar configuration is usually utilized,which leads to the mismatch with the outside DC grid with the bipolar configuration.Therefore,it will be important to develop those advanced DC/DC Interfaces for monopolarto-bipolar configurations of dc grid considering renewable energy integration.In the paper,a solution of monopolar-to-bipolar DC/DC converter has been proposed,with the corresponding control strategies according to the different scenarios.On the basis of theoretical analysis,a prototype has been implemented for the low-voltage small-scale laboratory environment.All experimental results validated both the correctness and effectiveness of the proposed DC-DC converter interface.This paper focus on the conversion of DC monopolar into DC bipolar,also explore different circuit topology suitable for different scenearios.Two applications based on following background are researched,background one: DC renewable energy monopolar output connect to DC bipolar gird under low voltage level;background two: in the situation of DC buildings,DC load operated on DC bipolar configuration,energy management strategy of new energy power generation,hybrid energy storage device and DC load.