EPE Association: EPE 2022 - DS3h: Power Electronics in Transmission and Distribution Systems

EPE 2022 - DS3h: Power Electronics in Transmission and Distribution Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2022 ECCE Europe - Conference > EPE 2022 - Topic 07: Power Supplies > EPE 2022 - DS3h: Power Electronics in Transmission and Distribution Systems

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   A Pre- and Discharge Unit for Capacitive DC-Links Based on a Dual-Switch Bidirectional Flyback Converter
By Madlen HOFFMANN [View]
[Download]

Abstract: This paper proposes a novel DC grid component that supplements conventional DC circuit breakers with a pre- and discharging functionality, thereby replacing conventional electromechanical solutions including lossy, bulky, and fault-prone pre- and discharging resistors. To reduce operational costs and energy consumption, this article proposes a bidirectional DC-DC converter for pre- and discharging purposes, which is based on an extended flyback topology with a dual-switch configuration on bothprimary and secondary side. This reduces the high voltage stress on the power semiconductors andprovides both a constant current behavior over a wide voltage range and an inherent overload protection for all capacitors on the load side. The operating principle, characteristic waveforms, and the converter design are presented. The proposed concept was verified on the basis of a realized prototype setup. With this, we are able to charge and discharge a 500 µF DC-link capacitor within less than 500 ms to and from a voltage of 700 V. Furthermore, the pre- and discharging unit fulfills increased functional safety requirements as the converter is self-sufficient after start-up and does not require an auxiliary power supply. Due to a very low quiescent current in the stand-by mode of merely 8.5 µA, it is particularly suited for battery-powered applications.

   Characterising the effect of an inverter on the regulation of the AC voltage using a frequency response identification technique
By Mohamed ALDARMON [View]
[Download]

Abstract: This paper presents a methodology to obtain a small-signal characteristics of a power electronic inverterin the frequency domain. The method is based on carrying out a series of simulations to observe theresponse of the inverter to a small voltage disturbance. The results obtained through the method provideinformation about the adequacy of the controller of the inverter and how it contributes to AC voltageregulation of the network. The paper describes the methodology and illustrates its use through a studycase of a low-power three-phase inverter.

   Distribution transformer voltage control using a single-phase matrixconverter
By Rui WANG [View]
[Download]

Abstract: A new topology is proposed for fully-electronic tap changers in distribution transformers. In every singlephase, the voltage is regulated by a 21 matrix converter, which can be extended using the concept ofmultilevel converters. The topology allows reaching the desired functionality with one single tap, whichreduces the cost of the transformer.

   Enabling large-scaled MMC EMT-RMS co-simulation by data exchange in the loop (DXiL)
By Xiong XIAO [View]
[Download]

Abstract: This paper presents a comprehensive co-simulation method of electro-magnetic (EMT) and electromechanical (RMS) dynamic models in MATLAB/Simulink to investigate transient stability in large scale hybrid AC/DC grids. The modeling of modular multilevel converter (MMC) as well as co simulation of EMT-RMS programs in MATLAB/Simulink is first described. For further reducing the unnecessary data exchange time between EMT and RMS programs, data exchange in the loop interaction method is introduced. With this method, the frequent data exchange through MATLAB workspace is avoided, and the co-simulation is thus accelerated significantly.

   Grounding Points in HV/MV Hybrid Transformer AuxiliaryConverters
By Adrian WIEMER [View]
[Download]

Abstract: The choice of grounding points in hybrid transformers is important to limit the overcurrents in case ofa single line to ground fault. In this paper different grounding points for hybrid transformers are compared based on a controller with active damping for the filter resonances. Based on the comparison the best grounding point for limiting the single line to ground fault current for hybrid transformer auxiliary converters and the MV grid is identified.

   Impedance Stability of Single-Phase LCL Grid-Connected Voltage Source Inverters with Wideband Gap Devices Under Different Control Approaches
By Ramy ALI [View]
[Download]

Abstract: This paper discusses the impedance stability of the grid connected VSI that is built using wide bandgap (WBG), SiC, or GaN semiconductors devices. The use of WBG devices have the benefits of higher switching frequency, lower losses, and smaller size. The impedance stability of the WBG-based VSI is studied under both grid side and inverter side current control. The impedance model of the VSI is developed and validated in Matlab/Simulink. Using this model, the variation of the VSI outputimpedance at increased switching frequencies is studied. The impedance stability is examined for thecase where the VSI is connected at different points in a distribution network. The CIGRE Europeanbenchmark LV network is used. The analysis reveals that the impedance stability of the grid-sidecurrent-controlled WBG-based VSI is improved at higher switching frequencies. Simulation results areprovided for verifying the theoretical analysis.

   Model predictive-based control technique for fault ride-through capability of VSG-based grid-forming converter
By Edris POURESMAEIL [View]
[Download]

Abstract: Increasing integration of renewable energy resources emphasizes the importance of the grid-forming virtual synchronous generator (VSG)-based converters. An important issue in the control structure of these converters is the fault ride-through (FRT) capability under fault operating condition. In this paper a model predictive-based FRT control strategy is proposed to limit the converter current while ensures high power quality during fault situation. The proposed control method provides a fast dynamic response, high power quality, improved performance, and a simpler control structure. The effective performance of the proposed control method, as well as its superior performance in comparison with the conventional PI-based control and a model predictive-based control method, are validated through simulation results in MATLAB/Simulink.

   Modelling Approaches of Power Systems Considering Grid-Connected Converters and Renewable Generation Dynamics
By Jaume GIRONA-BADIA [View]
[Download]

Abstract: This paper presents a comparative analysis of several modelling approaches of key elements used in simulations of power systems with renewable energy sources. Different models of synchronous generators, transmission lines, converters, wind generators and PV power plants are compared to assess the most suitable models for grid-connection studies. It also analyses how the dynamics of PV power plants and the mechanical dynamics of wind generators affect the electrical variables on the grid side. The models were compared in terms of precision, computational time and ease of use through simulations of load connection, short-circuits, disconnection of generators and lines in a benchmark system modelled in Simulink.

   Synchronization Stability of a Grid Forming Converter Under the Effect of Current Limit in Voltage Dips with VI Based Current Limiting Method: Analysis and Solution
By Siam Hasan KHAN [View]
[Download]

Abstract: This article deals with the synchronization stability in voltage dips of a Grid Forming Converter (GFC)operating with Virtual Impedance based current limiter. In the event of a grid fault, if the converter can'tevacuate the active power while limiting the current, stability issues arise. In this paper this effect isanalyzed, and a solution is proposed.

EPE 2022 - DS3h: Power Electronics in Transmission and Distribution Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2022 ECCE Europe - Conference > EPE 2022 - Topic 07: Power Supplies > EPE 2022 - DS3h: Power Electronics in Transmission and Distribution Systems
	[return to parent folder]

	A Pre- and Discharge Unit for Capacitive DC-Links Based on a Dual-Switch Bidirectional Flyback Converter By Madlen HOFFMANN	[View] [Download]
Abstract: This paper proposes a novel DC grid component that supplements conventional DC circuit breakers with a pre- and discharging functionality, thereby replacing conventional electromechanical solutions including lossy, bulky, and fault-prone pre- and discharging resistors. To reduce operational costs and energy consumption, this article proposes a bidirectional DC-DC converter for pre- and discharging purposes, which is based on an extended flyback topology with a dual-switch configuration on bothprimary and secondary side. This reduces the high voltage stress on the power semiconductors andprovides both a constant current behavior over a wide voltage range and an inherent overload protection for all capacitors on the load side. The operating principle, characteristic waveforms, and the converter design are presented. The proposed concept was verified on the basis of a realized prototype setup. With this, we are able to charge and discharge a 500 µF DC-link capacitor within less than 500 ms to and from a voltage of 700 V. Furthermore, the pre- and discharging unit fulfills increased functional safety requirements as the converter is self-sufficient after start-up and does not require an auxiliary power supply. Due to a very low quiescent current in the stand-by mode of merely 8.5 µA, it is particularly suited for battery-powered applications.

	Characterising the effect of an inverter on the regulation of the AC voltage using a frequency response identification technique By Mohamed ALDARMON	[View] [Download]
Abstract: This paper presents a methodology to obtain a small-signal characteristics of a power electronic inverterin the frequency domain. The method is based on carrying out a series of simulations to observe theresponse of the inverter to a small voltage disturbance. The results obtained through the method provideinformation about the adequacy of the controller of the inverter and how it contributes to AC voltageregulation of the network. The paper describes the methodology and illustrates its use through a studycase of a low-power three-phase inverter.

	Distribution transformer voltage control using a single-phase matrixconverter By Rui WANG	[View] [Download]
Abstract: A new topology is proposed for fully-electronic tap changers in distribution transformers. In every singlephase, the voltage is regulated by a 21 matrix converter, which can be extended using the concept ofmultilevel converters. The topology allows reaching the desired functionality with one single tap, whichreduces the cost of the transformer.

	Enabling large-scaled MMC EMT-RMS co-simulation by data exchange in the loop (DXiL) By Xiong XIAO	[View] [Download]
Abstract: This paper presents a comprehensive co-simulation method of electro-magnetic (EMT) and electromechanical (RMS) dynamic models in MATLAB/Simulink to investigate transient stability in large scale hybrid AC/DC grids. The modeling of modular multilevel converter (MMC) as well as co simulation of EMT-RMS programs in MATLAB/Simulink is first described. For further reducing the unnecessary data exchange time between EMT and RMS programs, data exchange in the loop interaction method is introduced. With this method, the frequent data exchange through MATLAB workspace is avoided, and the co-simulation is thus accelerated significantly.

	Grounding Points in HV/MV Hybrid Transformer AuxiliaryConverters By Adrian WIEMER	[View] [Download]
Abstract: The choice of grounding points in hybrid transformers is important to limit the overcurrents in case ofa single line to ground fault. In this paper different grounding points for hybrid transformers are compared based on a controller with active damping for the filter resonances. Based on the comparison the best grounding point for limiting the single line to ground fault current for hybrid transformer auxiliary converters and the MV grid is identified.

	Impedance Stability of Single-Phase LCL Grid-Connected Voltage Source Inverters with Wideband Gap Devices Under Different Control Approaches By Ramy ALI	[View] [Download]
Abstract: This paper discusses the impedance stability of the grid connected VSI that is built using wide bandgap (WBG), SiC, or GaN semiconductors devices. The use of WBG devices have the benefits of higher switching frequency, lower losses, and smaller size. The impedance stability of the WBG-based VSI is studied under both grid side and inverter side current control. The impedance model of the VSI is developed and validated in Matlab/Simulink. Using this model, the variation of the VSI outputimpedance at increased switching frequencies is studied. The impedance stability is examined for thecase where the VSI is connected at different points in a distribution network. The CIGRE Europeanbenchmark LV network is used. The analysis reveals that the impedance stability of the grid-sidecurrent-controlled WBG-based VSI is improved at higher switching frequencies. Simulation results areprovided for verifying the theoretical analysis.

	Model predictive-based control technique for fault ride-through capability of VSG-based grid-forming converter By Edris POURESMAEIL	[View] [Download]
Abstract: Increasing integration of renewable energy resources emphasizes the importance of the grid-forming virtual synchronous generator (VSG)-based converters. An important issue in the control structure of these converters is the fault ride-through (FRT) capability under fault operating condition. In this paper a model predictive-based FRT control strategy is proposed to limit the converter current while ensures high power quality during fault situation. The proposed control method provides a fast dynamic response, high power quality, improved performance, and a simpler control structure. The effective performance of the proposed control method, as well as its superior performance in comparison with the conventional PI-based control and a model predictive-based control method, are validated through simulation results in MATLAB/Simulink.

	Modelling Approaches of Power Systems Considering Grid-Connected Converters and Renewable Generation Dynamics By Jaume GIRONA-BADIA	[View] [Download]
Abstract: This paper presents a comparative analysis of several modelling approaches of key elements used in simulations of power systems with renewable energy sources. Different models of synchronous generators, transmission lines, converters, wind generators and PV power plants are compared to assess the most suitable models for grid-connection studies. It also analyses how the dynamics of PV power plants and the mechanical dynamics of wind generators affect the electrical variables on the grid side. The models were compared in terms of precision, computational time and ease of use through simulations of load connection, short-circuits, disconnection of generators and lines in a benchmark system modelled in Simulink.

	Synchronization Stability of a Grid Forming Converter Under the Effect of Current Limit in Voltage Dips with VI Based Current Limiting Method: Analysis and Solution By Siam Hasan KHAN	[View] [Download]
Abstract: This article deals with the synchronization stability in voltage dips of a Grid Forming Converter (GFC)operating with Virtual Impedance based current limiter. In the event of a grid fault, if the converter can'tevacuate the active power while limiting the current, stability issues arise. In this paper this effect isanalyzed, and a solution is proposed.