Due to the advanced features of multidirectional power transfer and fast smoothing of the power fluctuation in renewable energy systems,the multiple-active-bridge based power-electronic-transformer(MAB-PET)with integr...Due to the advanced features of multidirectional power transfer and fast smoothing of the power fluctuation in renewable energy systems,the multiple-active-bridge based power-electronic-transformer(MAB-PET)with integrated energy storage units is becoming popular.However,the accurate electromagnetic transient simulation of the MAB-PETs is extremely time-consuming due to the large number of circuit nodes and small time-step.This paper proposes a simplified EMT modeling approach for the MAB-PETs by employing the generalized state-space averaging method.First,the switching function method and Dommel algorithm are used to build the equivalent model of each power module.Further,the PET equivalent model is presented in a multi-port PM polymerization mode.The system is simplified by applying Fourier Decomposition to its state functions by ignoring high-order harmonics.Finally,a four-port equivalent voltage source circuit is obtained.The proposed simplified equivalent model is compared with the detailed model in PSCAD/EMTDC.Simulation results show the proposed approach has excellent accuracy and is 2–3 orders of magnitude faster than the DM.展开更多
The high-voltage direct current(HVDC)circuit breaker is becoming popular with the rapid development of the flexible HVDC grid for efficient DC fault ride-through purposes.This paper proposes a novel module for recipro...The high-voltage direct current(HVDC)circuit breaker is becoming popular with the rapid development of the flexible HVDC grid for efficient DC fault ride-through purposes.This paper proposes a novel module for reciprocating HVDC circuit breaker topology,whose branch connections are able to switch between series and parallel modes to limit the rising rate and interrupt the DC fault currents.Diode-bridge submodules(DBSMs)are used to compose the main branch for current interruption.Besides fault clearance,the proposed topology has the advantageous function of DC fault current limiting by employing DBSMs with bi-directional conduction capability.The topology can easily switch among branch connection modes through the assembled trans-valves,and their resistance and reactance are very small in the normal state when branches are in parallel and the values become promptly large in the transient state when the branches are series connected.With the modular design,it is easy to change the number of branches or sub-modules and the types of sub-modules to adapt to more specific needs.A 6-terminal modular multi-level converter(MMC)based HVDC grid is established in PSCAD/EMTDC,and various simulation scenarios are carried out to validate the proposed topology.展开更多
基金supported by Beijing Natural Science Foundation under grant 3222059.
文摘Due to the advanced features of multidirectional power transfer and fast smoothing of the power fluctuation in renewable energy systems,the multiple-active-bridge based power-electronic-transformer(MAB-PET)with integrated energy storage units is becoming popular.However,the accurate electromagnetic transient simulation of the MAB-PETs is extremely time-consuming due to the large number of circuit nodes and small time-step.This paper proposes a simplified EMT modeling approach for the MAB-PETs by employing the generalized state-space averaging method.First,the switching function method and Dommel algorithm are used to build the equivalent model of each power module.Further,the PET equivalent model is presented in a multi-port PM polymerization mode.The system is simplified by applying Fourier Decomposition to its state functions by ignoring high-order harmonics.Finally,a four-port equivalent voltage source circuit is obtained.The proposed simplified equivalent model is compared with the detailed model in PSCAD/EMTDC.Simulation results show the proposed approach has excellent accuracy and is 2–3 orders of magnitude faster than the DM.
基金supported by the National Key R&D Program of China(No.2018YFB0904600)the National Natural Science Foundation of China(No.51777072)
文摘The high-voltage direct current(HVDC)circuit breaker is becoming popular with the rapid development of the flexible HVDC grid for efficient DC fault ride-through purposes.This paper proposes a novel module for reciprocating HVDC circuit breaker topology,whose branch connections are able to switch between series and parallel modes to limit the rising rate and interrupt the DC fault currents.Diode-bridge submodules(DBSMs)are used to compose the main branch for current interruption.Besides fault clearance,the proposed topology has the advantageous function of DC fault current limiting by employing DBSMs with bi-directional conduction capability.The topology can easily switch among branch connection modes through the assembled trans-valves,and their resistance and reactance are very small in the normal state when branches are in parallel and the values become promptly large in the transient state when the branches are series connected.With the modular design,it is easy to change the number of branches or sub-modules and the types of sub-modules to adapt to more specific needs.A 6-terminal modular multi-level converter(MMC)based HVDC grid is established in PSCAD/EMTDC,and various simulation scenarios are carried out to validate the proposed topology.
