Grid-connected converters(GPC)are playing an increasingly important role in distribution networks.Performing electromagnetic transient(EMT)simulations on power electronics and distribution networks can significantly i...Grid-connected converters(GPC)are playing an increasingly important role in distribution networks.Performing electromagnetic transient(EMT)simulations on power electronics and distribution networks can significantly improve the analysis accuracy.However,the existing simulation softwarestruggles to handle distribution networks with a large number of power electronic switches,leading to unacceptable simulation times.To address this issue,a system-hierarchical multi-rate co-simulation framework is proposed.The system is hierarchically divided into different rate subsystems based on timescales,and solvers withdifferent simulation rates are used to solve them separately.A Taylor-series-based variable-step solver is proposed for power electronic systems,and numerical compensation algorithms are designed for multi-rate interfaces to improve the system stabilityand accuracy.Compared with commercial software,the proposed framework increased the simulation speed by more than 200 times in the studied case,involving 576 switching devices and 14 bus distribution networks,while contributing less than 1%to the relativeerror.展开更多
Current topology recommendation methods for DC-DC converters predominantly rely on manual experience, often involving the analysis of performance metrics (either manually or via a computer) and subsequently selecting ...Current topology recommendation methods for DC-DC converters predominantly rely on manual experience, often involving the analysis of performance metrics (either manually or via a computer) and subsequently selecting the most suitable topology to meet specific engineering requirements. However, as the number of available topologies increases and engineering demands vary, these methods are increasingly unable to provide optimal recommendations. To address this limitation, the present study presents an automatic optimization topology recommendation method (AO-TRM) for DC-DC converters that can accommodate a broad range of engineering requirements. The proposed method begins by identifying precise engineering requirements and then progresses through three key stages: topology generation, analysis, and recommendation. Two engineering applications are used as case studies to validate the effectiveness and capabilities of the proposed AO-TRM. From a pool of 1 186 topologies, the proposed method successfully identified and recommended optimal topologies based on specific requirements. Finally, experimental results are presented, demonstrating the capability, efficiency, and cost-effectiveness of the proposed method.展开更多
The common-mode current is an important indicator with transformerless photovoltaic inverters.However,up to now,there is not an accurate method to predict common-mode current in the inverter design process,resulting f...The common-mode current is an important indicator with transformerless photovoltaic inverters.However,up to now,there is not an accurate method to predict common-mode current in the inverter design process,resulting from inappropriate device selection or exceeded the expected common-mode current.In order to solve this problem,this paper proposes an accurate common-mode current prediction method based on graph theory for transformerless photovoltaic inverters.In this paper,the mathematic model of the common-mode current is derived using graph theory analysis method in the full-bridge topology,and it is used to predict common-mode current.The validity and correctness of the proposed prediction method are validated by simulation and experiment.The oscillation frequency and amplitude can be predicted by the proposed common-mode prediction method,whereas the traditional common-mode analysis method cannot.This paper provides a novel way to predict and analyze common-mode current in the transformerless photovoltaic inverters.展开更多
基金Supported by the National Key Research and Development Program(2023YFB3307000).
文摘Grid-connected converters(GPC)are playing an increasingly important role in distribution networks.Performing electromagnetic transient(EMT)simulations on power electronics and distribution networks can significantly improve the analysis accuracy.However,the existing simulation softwarestruggles to handle distribution networks with a large number of power electronic switches,leading to unacceptable simulation times.To address this issue,a system-hierarchical multi-rate co-simulation framework is proposed.The system is hierarchically divided into different rate subsystems based on timescales,and solvers withdifferent simulation rates are used to solve them separately.A Taylor-series-based variable-step solver is proposed for power electronic systems,and numerical compensation algorithms are designed for multi-rate interfaces to improve the system stabilityand accuracy.Compared with commercial software,the proposed framework increased the simulation speed by more than 200 times in the studied case,involving 576 switching devices and 14 bus distribution networks,while contributing less than 1%to the relativeerror.
基金Supported by the National Science Fund for Distinguished Young Scholars(52325704)the Key Program of National Natural Science Foundation of China(52237008).
文摘Current topology recommendation methods for DC-DC converters predominantly rely on manual experience, often involving the analysis of performance metrics (either manually or via a computer) and subsequently selecting the most suitable topology to meet specific engineering requirements. However, as the number of available topologies increases and engineering demands vary, these methods are increasingly unable to provide optimal recommendations. To address this limitation, the present study presents an automatic optimization topology recommendation method (AO-TRM) for DC-DC converters that can accommodate a broad range of engineering requirements. The proposed method begins by identifying precise engineering requirements and then progresses through three key stages: topology generation, analysis, and recommendation. Two engineering applications are used as case studies to validate the effectiveness and capabilities of the proposed AO-TRM. From a pool of 1 186 topologies, the proposed method successfully identified and recommended optimal topologies based on specific requirements. Finally, experimental results are presented, demonstrating the capability, efficiency, and cost-effectiveness of the proposed method.
基金This work was supported by the National Natural Science Foundation of China under Grant 51577010the Fundamental Research Funds for the Central Universities under Grant 2017JBM054the Natural Science Foundation of Guangdong Province under Grant 1714060000016.
文摘The common-mode current is an important indicator with transformerless photovoltaic inverters.However,up to now,there is not an accurate method to predict common-mode current in the inverter design process,resulting from inappropriate device selection or exceeded the expected common-mode current.In order to solve this problem,this paper proposes an accurate common-mode current prediction method based on graph theory for transformerless photovoltaic inverters.In this paper,the mathematic model of the common-mode current is derived using graph theory analysis method in the full-bridge topology,and it is used to predict common-mode current.The validity and correctness of the proposed prediction method are validated by simulation and experiment.The oscillation frequency and amplitude can be predicted by the proposed common-mode prediction method,whereas the traditional common-mode analysis method cannot.This paper provides a novel way to predict and analyze common-mode current in the transformerless photovoltaic inverters.
