EPE Association: EPE 2017 - LS6a: Power Electronics in Grids II

EPE 2017 - LS6a: Power Electronics in Grids II
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2017 ECCE Europe - Conference > EPE 2017 - Topic 06: Grids and Smart Grids > EPE 2017 - LS6a: Power Electronics in Grids II

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   Grid Integration and Control of a Stacked Multicell Converter under Asymmetric Grid Conditions
By Benjamin FREUDENBERG [View]
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Abstract: The increasing number of renewable energy sources and their integration into the medium voltage grid leads to an increasing interest in multilevel structures for the interfacing power electronic converters. A feasible topology for MV applications is the Stacked Multicell Converter (SMC) offering a modular structure and several voltage levels. A robust control, current limiting strategies under grid faults and fault ride-through operation of the converter are required to enable grid integration. In this work, the control of the SMC is investigated concerning balancing of internal DC voltages and handling of asymmetric grid conditions. The control concepts are verified with a scaled experimental test setup consisting of a 7-level SMC connected to the LV grid.

   Stability of grid-connected modular multilevel converter with open- and closed-loop ac-side control
By Mebtu BEZA [View]
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Abstract: The stability of grid-connected modular multilevel converter (MMC) under two control strategies is studied in this paper. For this purpose, the ac-side input admittance of the MMC is derived under open- and closed-loop ac-side control strategies. The derived analytical models are used to investigate the impact of the two approaches on the stability of the MMC and detailed time-domain simulations are used to the verify the theoretical findings.

   Transformer Inrush Current Mitigation Concept for Hybrid Transformers
By Johannes BURKARD [View]
[Download]

Abstract: Abstract Large inrush currents can occur when power transformers are connected to the grid. In the past, a wide range of countermeasures has been developed whereof the application of power electronic converters recently received more attention. With hybrid transformers combining a conventional transformer with a power electronic converter, the elimination of inrush currents can be realized without considerable additional hardware effort. For such hybrid transformers, a novel mitigation procedure is proposed, which is based on the injection of a synchronous core flux before the transformer is connected to the grid. In addition, dedicated demagnetization strategies applicable for grid connected converters with filter elements are presented. The effectiveness of the proposed procedure is verified by comprehensive simulations and a comparison to a conventional method.

   Use of Modular Multilevel Converter in Multi-Terminal DC Transmission Network: Reduced Scale Set-up and Experimental Results
By Serge GAVIN [View]
[Download]

Abstract: In the frame of a collaboration project within Swiss Competence Centre for Energy Research, a MultiTerminal DC pilot has been implemented. For the interaction with the medium voltage AC grid, aModular Multilevel Converter has been designed for its features in low harmonic content, scalability,and flexibility. The control of converters in the MTDC network implements a non-dead band voltagecontrol. The Energy buffering of the MMC converter will allow the converter to sustain either AC orDC grids. The operation of the MMC converter in an MTDC network containing three converter isverified experimentally in a reduced-scale pilot.

EPE 2017 - LS6a: Power Electronics in Grids II
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2017 ECCE Europe - Conference > EPE 2017 - Topic 06: Grids and Smart Grids > EPE 2017 - LS6a: Power Electronics in Grids II
	[return to parent folder]

	Grid Integration and Control of a Stacked Multicell Converter under Asymmetric Grid Conditions By Benjamin FREUDENBERG	[View] [Download]
Abstract: The increasing number of renewable energy sources and their integration into the medium voltage grid leads to an increasing interest in multilevel structures for the interfacing power electronic converters. A feasible topology for MV applications is the Stacked Multicell Converter (SMC) offering a modular structure and several voltage levels. A robust control, current limiting strategies under grid faults and fault ride-through operation of the converter are required to enable grid integration. In this work, the control of the SMC is investigated concerning balancing of internal DC voltages and handling of asymmetric grid conditions. The control concepts are verified with a scaled experimental test setup consisting of a 7-level SMC connected to the LV grid.

	Stability of grid-connected modular multilevel converter with open- and closed-loop ac-side control By Mebtu BEZA	[View] [Download]
Abstract: The stability of grid-connected modular multilevel converter (MMC) under two control strategies is studied in this paper. For this purpose, the ac-side input admittance of the MMC is derived under open- and closed-loop ac-side control strategies. The derived analytical models are used to investigate the impact of the two approaches on the stability of the MMC and detailed time-domain simulations are used to the verify the theoretical findings.

	Transformer Inrush Current Mitigation Concept for Hybrid Transformers By Johannes BURKARD	[View] [Download]
Abstract: Abstract Large inrush currents can occur when power transformers are connected to the grid. In the past, a wide range of countermeasures has been developed whereof the application of power electronic converters recently received more attention. With hybrid transformers combining a conventional transformer with a power electronic converter, the elimination of inrush currents can be realized without considerable additional hardware effort. For such hybrid transformers, a novel mitigation procedure is proposed, which is based on the injection of a synchronous core flux before the transformer is connected to the grid. In addition, dedicated demagnetization strategies applicable for grid connected converters with filter elements are presented. The effectiveness of the proposed procedure is verified by comprehensive simulations and a comparison to a conventional method.

	Use of Modular Multilevel Converter in Multi-Terminal DC Transmission Network: Reduced Scale Set-up and Experimental Results By Serge GAVIN	[View] [Download]
Abstract: In the frame of a collaboration project within Swiss Competence Centre for Energy Research, a MultiTerminal DC pilot has been implemented. For the interaction with the medium voltage AC grid, aModular Multilevel Converter has been designed for its features in low harmonic content, scalability,and flexibility. The control of converters in the MTDC network implements a non-dead band voltagecontrol. The Energy buffering of the MMC converter will allow the converter to sustain either AC orDC grids. The operation of the MMC converter in an MTDC network containing three converter isverified experimentally in a reduced-scale pilot.