EPE Association: EPE 2014 - LS4f: Power Electronics in Transmission and Distribution Systems

EPE 2014 - LS4f: Power Electronics in Transmission and Distribution Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2014 ECCE Europe - Conference > EPE 2014 - Topic 06: Grids and Smart Grids > EPE 2014 - LS4f: Power Electronics in Transmission and Distribution Systems

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   Low-Voltage Fault Ride Through of the Modular Multilevel Converter in a Battery Energy Storage System Connected Directly to the Medium Voltage Grid
By Andre HILLERS, Jürgen BIELA [View]
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Abstract: Nowadays, even small and medium sized power generators are required to ride through low-voltage faults without disconnecting themselves from the grid. To the modular multilevel converter (MMC) in a battery energy storage system based on split batteries (sBESS), this presents a unique requirement: In case of a low-voltage grid-fault, the arm voltages leave their steady-state trajectory which can lead to undervoltage or overvoltage in the modules, provoking an unacceptable shutdown of the whole converter. This paper presents a new control strategy to support the arm voltages by making use of the split batteries in case of a fault. The converter can ride through consecutive grid-faults while continuing to supply a current to support the grid and can immediately resume operation after the fault is cleared.

   MMC Circulating Current Reference Calculation in ABC Frame by means of Lagrange Multipliers for Ensuring Constant DC Power under Unbalanced Grid Conditions
By Gilbert BERGNA, Jon Are SUUL, Erik BERNE, Philippe EGROT, AMIR ARZANDE, Jean-Claude VANNIER, Marta MOLINAS [View]
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Abstract: This work presents a general approach for calculating the circulating current references of Modular Multilevel Converters (MMC) based on mathematical optimization by means of Lagrange Multipliers in the ABC frame. The resulting control method is especially suitable for operation of MMCs in multi-terminal HVDC systems, under both balanced and unbalanced AC grid voltages, since it is designed for eliminating oscillations in the DC power flow independently from AC grid voltage conditions. Furthermore, it has been shown that the power flow in the DC side of the MMC is most effectively decoupled from transients in the AC grid if the main power reference of the MMC is established by the circulating current control instead of with the grid current.

   Modular Multilevel Converter Based on Full Bridge Cells for Multi-Terminal DC Transmission
By Sungmin KIM, Shenghui CUI, Seung-Ki SUL [View]
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Abstract: In the Multi-Terminal DC (MTDC) power transmission system, the power flows according to the DC voltages of the terminals and the line impedances. And, the power flowing through each DC line in the mesh MTDC system is not able to be controlled independently. In this paper, a Modular Multilevel Converter based on Full Bridge cells (MMC-FB) is proposed for auxiliary voltage control in the mesh type MTDC system. To control the MMC-FB in four-quadrant, the capacitor voltage balancing method is also proposed with three equivalent circuit models. All control algorithm associated with the proposed MTDC has been confirmed by computer simulation.

   Operation of HVDC Modular Multilevel Converters under DC pole imbalances
By Adria JUNYENT-FERRE, Philip CLEMOW, Michael MERLIN, Timothy GREEN [View]
[Download]

Abstract: Operation of HVDC converters under HVDC pole voltage imbalances is analysed. Asymmetrical HVDC pole current injection is achieved by directing current to the ground return path through a device installed in the AC side of the converter. Several operation modes, including asymmetric monopole, are presented and their sizing requirements are discussed.

EPE 2014 - LS4f: Power Electronics in Transmission and Distribution Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2014 ECCE Europe - Conference > EPE 2014 - Topic 06: Grids and Smart Grids > EPE 2014 - LS4f: Power Electronics in Transmission and Distribution Systems
	[return to parent folder]

	Low-Voltage Fault Ride Through of the Modular Multilevel Converter in a Battery Energy Storage System Connected Directly to the Medium Voltage Grid By Andre HILLERS, Jürgen BIELA	[View] [Download]
Abstract: Nowadays, even small and medium sized power generators are required to ride through low-voltage faults without disconnecting themselves from the grid. To the modular multilevel converter (MMC) in a battery energy storage system based on split batteries (sBESS), this presents a unique requirement: In case of a low-voltage grid-fault, the arm voltages leave their steady-state trajectory which can lead to undervoltage or overvoltage in the modules, provoking an unacceptable shutdown of the whole converter. This paper presents a new control strategy to support the arm voltages by making use of the split batteries in case of a fault. The converter can ride through consecutive grid-faults while continuing to supply a current to support the grid and can immediately resume operation after the fault is cleared.

	MMC Circulating Current Reference Calculation in ABC Frame by means of Lagrange Multipliers for Ensuring Constant DC Power under Unbalanced Grid Conditions By Gilbert BERGNA, Jon Are SUUL, Erik BERNE, Philippe EGROT, AMIR ARZANDE, Jean-Claude VANNIER, Marta MOLINAS	[View] [Download]
Abstract: This work presents a general approach for calculating the circulating current references of Modular Multilevel Converters (MMC) based on mathematical optimization by means of Lagrange Multipliers in the ABC frame. The resulting control method is especially suitable for operation of MMCs in multi-terminal HVDC systems, under both balanced and unbalanced AC grid voltages, since it is designed for eliminating oscillations in the DC power flow independently from AC grid voltage conditions. Furthermore, it has been shown that the power flow in the DC side of the MMC is most effectively decoupled from transients in the AC grid if the main power reference of the MMC is established by the circulating current control instead of with the grid current.

	Modular Multilevel Converter Based on Full Bridge Cells for Multi-Terminal DC Transmission By Sungmin KIM, Shenghui CUI, Seung-Ki SUL	[View] [Download]
Abstract: In the Multi-Terminal DC (MTDC) power transmission system, the power flows according to the DC voltages of the terminals and the line impedances. And, the power flowing through each DC line in the mesh MTDC system is not able to be controlled independently. In this paper, a Modular Multilevel Converter based on Full Bridge cells (MMC-FB) is proposed for auxiliary voltage control in the mesh type MTDC system. To control the MMC-FB in four-quadrant, the capacitor voltage balancing method is also proposed with three equivalent circuit models. All control algorithm associated with the proposed MTDC has been confirmed by computer simulation.

	Operation of HVDC Modular Multilevel Converters under DC pole imbalances By Adria JUNYENT-FERRE, Philip CLEMOW, Michael MERLIN, Timothy GREEN	[View] [Download]
Abstract: Operation of HVDC converters under HVDC pole voltage imbalances is analysed. Asymmetrical HVDC pole current injection is achieved by directing current to the ground return path through a device installed in the AC side of the converter. Several operation modes, including asymmetric monopole, are presented and their sizing requirements are discussed.