EPE Association: EPE 2016

EPE 2016 - LS2f: HVDC
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 06: Grids and Smart Grids > EPE 2016 - LS2f: HVDC

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   A new DC breaker with reduced need for semiconductors
By Lennart ÄNGQUIST [View]
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Abstract: A renewed interest for dc breakers has evolved owing to the visions of connecting several HVDC links into a HVDC grid. Several breaker concepts have been presented and some also have been implemented and tested. A new approach is proposed in this paper. The fundamental principle is to take advantage of the fast recovery of the voltage withstand capability in a Vacuum Interrupter (VI) when the current is temporarily forced to zero using a low-voltage power electronic converter. The latter excites an oscillating current in a passive resonant circuit during the time interval needed to mechanically separate the contacts in the interrupter. The sum of the line current (to be interrupted) and the oscillating current passes through the vacuum interrupter and experiences zero-crossings when the amplitude of the oscillating current exceeds the line current. The most important benefit of the proposed concept is that a favorable cost can be achieved, because excitation of the oscillating current only requires a low output voltage (compared to the breaking voltage across the VI terminals) from the converter. The total voltage rating of the semiconductors in the latter therefore is only a fraction of that needed in a hybrid HVDC breaker and, additionally, they are not requested to turn off the main current but rather to commutate close to current zero-crossings. Experimental verification of the concept has been performed with current up to 1.6 kA against 1.2 kV.

   Cost-Effective Solutions for Handling DC Faults in VSC HVDC Transmission
By Arman HASSANPOOR [View]
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Abstract: Utilization of voltage-source converters (VSC) in high-voltage direct current (HVDC) transmission systemsare increased in recent years. This paper proposes cost-effective solutions for handling dc-sidefaults in VSC HVDC bipolar transmission. The basic idea of this paper is to replace the existing mechanicalneutral bus switch (NBS), which is normally composed of resonance circuit and mechanicalbreaker, with semiconductor-based dc breakers. Consequently, converter blocked-time can be reducedsignificantly and ac grid can be supported with reactive power within a short time. The proposed methodwill improve the stability of the connected ac grid.

   Internal Control Stability Assessment Method of a VSC-based transmission grid
By Guillaume DENIS [View]
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Abstract: The multiplication of interfaced generation units connected to the utility grid might form VSC-basedtransmission grids in a near future. To support the utility grid autonomously, the converters mustprovide grid-forming capabilities and be connected in parallel. As the structure of a transmission gridis changing and unknown, these requirements presume a robust local voltage control for each highpowerVSC, to face various network topologies. Indeed, the stability is challenged when voltagecontrolledVSCs are close to each other, namely, when the tie-impedance is low. The presentcontribution describes an impedance-based criterion method as a convenient and effective tool forassessing the stability of the voltage control of converters in a VSC-based transmission grid. Themethod is successfully applied to a typical two-VSC system to anticipate unstable situations.

   The Series Bridge Converter (SBC): A Hybrid Modular Multilevel Converter for HVDC applications
By Emmanuel AMANKWAH [View]
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Abstract: This paper presents a novel hybrid modular multilevel voltage source converter suitable for HVDC applications. It has the advantages of other modular multilevel topologies and can be made more compact making it attractive for offshore stations and city infeed applications. The Operating principle of the converter and internal energy management are discussed with simulation results from a scaled medium voltage demonstrator presented to validate the concepts.

EPE 2016 - LS2f: HVDC
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 06: Grids and Smart Grids > EPE 2016 - LS2f: HVDC
	[return to parent folder]

	A new DC breaker with reduced need for semiconductors By Lennart ÄNGQUIST	[View] [Download]
Abstract: A renewed interest for dc breakers has evolved owing to the visions of connecting several HVDC links into a HVDC grid. Several breaker concepts have been presented and some also have been implemented and tested. A new approach is proposed in this paper. The fundamental principle is to take advantage of the fast recovery of the voltage withstand capability in a Vacuum Interrupter (VI) when the current is temporarily forced to zero using a low-voltage power electronic converter. The latter excites an oscillating current in a passive resonant circuit during the time interval needed to mechanically separate the contacts in the interrupter. The sum of the line current (to be interrupted) and the oscillating current passes through the vacuum interrupter and experiences zero-crossings when the amplitude of the oscillating current exceeds the line current. The most important benefit of the proposed concept is that a favorable cost can be achieved, because excitation of the oscillating current only requires a low output voltage (compared to the breaking voltage across the VI terminals) from the converter. The total voltage rating of the semiconductors in the latter therefore is only a fraction of that needed in a hybrid HVDC breaker and, additionally, they are not requested to turn off the main current but rather to commutate close to current zero-crossings. Experimental verification of the concept has been performed with current up to 1.6 kA against 1.2 kV.

	Cost-Effective Solutions for Handling DC Faults in VSC HVDC Transmission By Arman HASSANPOOR	[View] [Download]
Abstract: Utilization of voltage-source converters (VSC) in high-voltage direct current (HVDC) transmission systemsare increased in recent years. This paper proposes cost-effective solutions for handling dc-sidefaults in VSC HVDC bipolar transmission. The basic idea of this paper is to replace the existing mechanicalneutral bus switch (NBS), which is normally composed of resonance circuit and mechanicalbreaker, with semiconductor-based dc breakers. Consequently, converter blocked-time can be reducedsignificantly and ac grid can be supported with reactive power within a short time. The proposed methodwill improve the stability of the connected ac grid.

	Internal Control Stability Assessment Method of a VSC-based transmission grid By Guillaume DENIS	[View] [Download]
Abstract: The multiplication of interfaced generation units connected to the utility grid might form VSC-basedtransmission grids in a near future. To support the utility grid autonomously, the converters mustprovide grid-forming capabilities and be connected in parallel. As the structure of a transmission gridis changing and unknown, these requirements presume a robust local voltage control for each highpowerVSC, to face various network topologies. Indeed, the stability is challenged when voltagecontrolledVSCs are close to each other, namely, when the tie-impedance is low. The presentcontribution describes an impedance-based criterion method as a convenient and effective tool forassessing the stability of the voltage control of converters in a VSC-based transmission grid. Themethod is successfully applied to a typical two-VSC system to anticipate unstable situations.

	The Series Bridge Converter (SBC): A Hybrid Modular Multilevel Converter for HVDC applications By Emmanuel AMANKWAH	[View] [Download]
Abstract: This paper presents a novel hybrid modular multilevel voltage source converter suitable for HVDC applications. It has the advantages of other modular multilevel topologies and can be made more compact making it attractive for offshore stations and city infeed applications. The Operating principle of the converter and internal energy management are discussed with simulation results from a scaled medium voltage demonstrator presented to validate the concepts.