The DC distribution system is an important development direction of the distribution system,which can improve the reliability and the quality of the power supply,and support the new energy,the energy storage,the elect...The DC distribution system is an important development direction of the distribution system,which can improve the reliability and the quality of the power supply,and support the new energy,the energy storage,the electric vehicles,and the flexible access of AC and DC loads to grid.To realize the demonstration application of the DC distribution technology,China's first demonstration project of the medium voltage DC distribution network will be built in Zhuhai,Guangdong Province to support the construction of the city energy internet.First,this paper analyzes the demand of the DC distribution network project,and puts forward the construction content and construction target.Then,it designs and analyzes the electrical connection mode,system operation mode,and startup and shutdown mode of the DC distribution network,and proposes the overall project construction plan.Finally,it conducts the specific project design and analysis,which mainly in elude the selection of equipment such as inverters,DC transformers and DC circuit breakers,the design and analysis of the DC control and protection system,the design and analysis of the overvoltage protection and the configuration scheme of the lightning arrester,and analysis of the system transient characteristics.The design and analysis of the engineering program is a combination of China's distribution network engineering practice and technical characteristics,which lays a solid foundation for the advancement of the DC power distribution technology in China,and has reference value and demonstration effect for the design and construction of other projects.展开更多
The two main challenges of medium voltage direct current(MVDC)distribution network are the flexible control of power flow(PF)and fault protection.In this paper,the power flow controller(PFC)is introduced to regulate t...The two main challenges of medium voltage direct current(MVDC)distribution network are the flexible control of power flow(PF)and fault protection.In this paper,the power flow controller(PFC)is introduced to regulate the PF and inhibit the fault current during the DC fault.The coordination strategy of series-parallel PFC(SP-PFC)and hybrid DC circuit breaker(DCCB)is proposed.By regulating the polarity and magnitude of SP-PFC output voltage during the fault,the rising speed of fault current can be suppressed so as to reduce the breaking current of hybrid DCCB.The access mode of SP-PFC to the MVDC distribution network and its topology are analyzed,and the coordination strategy between SP-PFC and hybrid DCCB is investigated.Moreover,the emergency control and bypass control strategies of SP-PFC are developed.On this basis,the mathematical model of SP-PFC in different fault stages is derived.With the equivalent model of SP-PFC,the fault current of the MVDC distribution network can be calculated accurately.A simulation model of the MVDC distribution network containing SP-PFC is established in MATLAB/Simulink.The fault current calculation result is compared with the simulation result,and the effectiveness of the proposed coordination strategy is verified.展开更多
文摘The DC distribution system is an important development direction of the distribution system,which can improve the reliability and the quality of the power supply,and support the new energy,the energy storage,the electric vehicles,and the flexible access of AC and DC loads to grid.To realize the demonstration application of the DC distribution technology,China's first demonstration project of the medium voltage DC distribution network will be built in Zhuhai,Guangdong Province to support the construction of the city energy internet.First,this paper analyzes the demand of the DC distribution network project,and puts forward the construction content and construction target.Then,it designs and analyzes the electrical connection mode,system operation mode,and startup and shutdown mode of the DC distribution network,and proposes the overall project construction plan.Finally,it conducts the specific project design and analysis,which mainly in elude the selection of equipment such as inverters,DC transformers and DC circuit breakers,the design and analysis of the DC control and protection system,the design and analysis of the overvoltage protection and the configuration scheme of the lightning arrester,and analysis of the system transient characteristics.The design and analysis of the engineering program is a combination of China's distribution network engineering practice and technical characteristics,which lays a solid foundation for the advancement of the DC power distribution technology in China,and has reference value and demonstration effect for the design and construction of other projects.
基金supported by the National Key Research and Development Program of China(No.2018YFB0904600)the National Natural Science Foundation of China(No.52077017)。
文摘The two main challenges of medium voltage direct current(MVDC)distribution network are the flexible control of power flow(PF)and fault protection.In this paper,the power flow controller(PFC)is introduced to regulate the PF and inhibit the fault current during the DC fault.The coordination strategy of series-parallel PFC(SP-PFC)and hybrid DC circuit breaker(DCCB)is proposed.By regulating the polarity and magnitude of SP-PFC output voltage during the fault,the rising speed of fault current can be suppressed so as to reduce the breaking current of hybrid DCCB.The access mode of SP-PFC to the MVDC distribution network and its topology are analyzed,and the coordination strategy between SP-PFC and hybrid DCCB is investigated.Moreover,the emergency control and bypass control strategies of SP-PFC are developed.On this basis,the mathematical model of SP-PFC in different fault stages is derived.With the equivalent model of SP-PFC,the fault current of the MVDC distribution network can be calculated accurately.A simulation model of the MVDC distribution network containing SP-PFC is established in MATLAB/Simulink.The fault current calculation result is compared with the simulation result,and the effectiveness of the proposed coordination strategy is verified.