The existing power management schemes for interlinked AC-DC microgrids have several operational drawbacks.Some of the existing control schemes are designed with the main objective of sharing power among the interlinke...The existing power management schemes for interlinked AC-DC microgrids have several operational drawbacks.Some of the existing control schemes are designed with the main objective of sharing power among the interlinked microgrids based on their loading conditions,while other schemes regulate the voltage of the interlinked microgrids without considering the specific loading conditions.However,the existing schemes cannot achieve both objectives efficiently.To address these issues,an autonomous power management scheme is proposed,which explicitly considers the specific loading condition of the DC microgrid before importing power from the interlinked AC microgrid.This strategy enables voltage regulation in the DC microgrid,and also reduces the number of converters in operation.The proposed scheme is fully autonomous while it retains the plug-nplay features for generators and tie-converters.The performance of the proposed control scheme has been validated under different operating scenarios.The results demonstrate the effectiveness of the proposed scheme in managing the power deficit in the DC microgrid efficiently and autonomously while maintaining the better voltage regulation in the DC microgrid.展开更多
In May 1983,the governor of Hebei province,Zhang Shuguang,and the governor of the US state of Iowa,Terry Branstad,signed an agreemen t to establish friendly relations between the two areas in the state capital,Des Moi...In May 1983,the governor of Hebei province,Zhang Shuguang,and the governor of the US state of Iowa,Terry Branstad,signed an agreemen t to establish friendly relations between the two areas in the state capital,Des Moines.Two years later,in May 1985,Xi Jinping,secretary of the Zhengding County Committee of the Communist Party of China in Hebei.展开更多
The equilibrium between dc bus voltage and ac bus frequency(Udc-f equilibrium)is the algorithm core of unified control strategies for ac-dc interlinking converters(ILCs),because the equilibrium implements certain mech...The equilibrium between dc bus voltage and ac bus frequency(Udc-f equilibrium)is the algorithm core of unified control strategies for ac-dc interlinking converters(ILCs),because the equilibrium implements certain mechanism.However,what the mechanism is has not been explicitly explored,which hinders further studies on unified control.This paper reveals that the state-space model of a Udc-f equilibrium controlled ILC is highly similar to that of a shaft-to-shaft machines system.Hence a detailed mechanism is dis-covered and named“virtual shaft-to-shaft machine(VSSM)”mechanism.A significant feature of VSSM mechanism is self-synchro-nization without current sampling or ac voltage sampling.展开更多
The stability problem arising from the DC-link voltage outer loop and current inner loop control in weak-grid-tied interlinking voltage-source converters(VSC)system has been extensively investigated.However,the differ...The stability problem arising from the DC-link voltage outer loop and current inner loop control in weak-grid-tied interlinking voltage-source converters(VSC)system has been extensively investigated.However,the different impacts on system stability caused by these controller parameters have not been well solved.A three-port hybrid AC/DC admittance-based model for VSC taking into account AC-and DC-side dynamics is developed for revealing the mechanism intuitively on the formation of the positive and negative feedback effects in the DC-link voltage control loop.Subsequently,the stability characteristics of the voltage outer loop and current inner loop controller parameters on VSC are analyzed.Compared to adjusting the voltage outer loop controller parameters which has significant effort on the dynamic regulation characteristics,it is more sensitive on system stability by the parameter change of the current inner loop controller.Theoretical results,along with experimental verification,are provided to validate the analysis.展开更多
Phase-shift(PS)dual-active-bridge(DAB)interlinking converters(ILCs)exhibit considerable potential in linking DC buses.DC ILC control research is focused on addressing three issues,namely modular series-parallel connec...Phase-shift(PS)dual-active-bridge(DAB)interlinking converters(ILCs)exhibit considerable potential in linking DC buses.DC ILC control research is focused on addressing three issues,namely modular series-parallel connection,control adaptability in various microgrid-operation modes,and microgrid stability with constant power loads.However,PS DAB converters operating with open-loop control cannot maintain bus voltage when load changes.Based on the open-loop controlled resonant converters which are called DC transformers(DCXs),this study proposes a closed-loop de-transformer(CL-DCX)control method for DAB ILCs.In conventional control techniques,specialized control loops are used for addressing each control issue.It is hard to combine these loops to address all three control issues simultaneously.By contrast,the CL-DCX control method is simple and can address all three control issues simultaneously.The proposed CL-DCX control method is conducive for implementation in independent microgrids and may benefit medium-voltage applications because of its versatility and simplicity.展开更多
文摘The existing power management schemes for interlinked AC-DC microgrids have several operational drawbacks.Some of the existing control schemes are designed with the main objective of sharing power among the interlinked microgrids based on their loading conditions,while other schemes regulate the voltage of the interlinked microgrids without considering the specific loading conditions.However,the existing schemes cannot achieve both objectives efficiently.To address these issues,an autonomous power management scheme is proposed,which explicitly considers the specific loading condition of the DC microgrid before importing power from the interlinked AC microgrid.This strategy enables voltage regulation in the DC microgrid,and also reduces the number of converters in operation.The proposed scheme is fully autonomous while it retains the plug-nplay features for generators and tie-converters.The performance of the proposed control scheme has been validated under different operating scenarios.The results demonstrate the effectiveness of the proposed scheme in managing the power deficit in the DC microgrid efficiently and autonomously while maintaining the better voltage regulation in the DC microgrid.
文摘In May 1983,the governor of Hebei province,Zhang Shuguang,and the governor of the US state of Iowa,Terry Branstad,signed an agreemen t to establish friendly relations between the two areas in the state capital,Des Moines.Two years later,in May 1985,Xi Jinping,secretary of the Zhengding County Committee of the Communist Party of China in Hebei.
基金supported in part by the National Natural Science Foundation of China under Grants 51877117 and 52007096the International Joint Mission On Climate Change and Carbon Neutralitythe Major Science and Technology Innovation Project of Jiangsu Province of China under Grant BE2022038.
文摘The equilibrium between dc bus voltage and ac bus frequency(Udc-f equilibrium)is the algorithm core of unified control strategies for ac-dc interlinking converters(ILCs),because the equilibrium implements certain mechanism.However,what the mechanism is has not been explicitly explored,which hinders further studies on unified control.This paper reveals that the state-space model of a Udc-f equilibrium controlled ILC is highly similar to that of a shaft-to-shaft machines system.Hence a detailed mechanism is dis-covered and named“virtual shaft-to-shaft machine(VSSM)”mechanism.A significant feature of VSSM mechanism is self-synchro-nization without current sampling or ac voltage sampling.
基金supported by the National Natural Science Foundation of China(No.52177184)the Shanghai Municipality on Natural Science Fund(No.21ZR1425300).
文摘The stability problem arising from the DC-link voltage outer loop and current inner loop control in weak-grid-tied interlinking voltage-source converters(VSC)system has been extensively investigated.However,the different impacts on system stability caused by these controller parameters have not been well solved.A three-port hybrid AC/DC admittance-based model for VSC taking into account AC-and DC-side dynamics is developed for revealing the mechanism intuitively on the formation of the positive and negative feedback effects in the DC-link voltage control loop.Subsequently,the stability characteristics of the voltage outer loop and current inner loop controller parameters on VSC are analyzed.Compared to adjusting the voltage outer loop controller parameters which has significant effort on the dynamic regulation characteristics,it is more sensitive on system stability by the parameter change of the current inner loop controller.Theoretical results,along with experimental verification,are provided to validate the analysis.
基金supported in part by the National Natural Science Foundation of China(52007096 and 51877117)in part by the Delta Power Electronics Research and Education Development Program(DREM2019005).
文摘Phase-shift(PS)dual-active-bridge(DAB)interlinking converters(ILCs)exhibit considerable potential in linking DC buses.DC ILC control research is focused on addressing three issues,namely modular series-parallel connection,control adaptability in various microgrid-operation modes,and microgrid stability with constant power loads.However,PS DAB converters operating with open-loop control cannot maintain bus voltage when load changes.Based on the open-loop controlled resonant converters which are called DC transformers(DCXs),this study proposes a closed-loop de-transformer(CL-DCX)control method for DAB ILCs.In conventional control techniques,specialized control loops are used for addressing each control issue.It is hard to combine these loops to address all three control issues simultaneously.By contrast,the CL-DCX control method is simple and can address all three control issues simultaneously.The proposed CL-DCX control method is conducive for implementation in independent microgrids and may benefit medium-voltage applications because of its versatility and simplicity.
