EPE Association: EPE 2018 - DS1f: HVDC and FACTS

EPE 2018 - DS1f: HVDC and FACTS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 06: Grids, Smart Grids, AC & DC > EPE 2018 - DS1f: HVDC and FACTS

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   A Communication-less Cooperative dc Voltage Control Technique for a Multi-terminal HVDC Transmission System using Hinf Control
By Roberto SANDANO [View]
[Download]

Abstract: New and upcoming regulations are requiring converters in high voltage direct current (HVDC) connections to be able provide a rapid response to support the stability of the main synchronous network to which they are connected. However, currently proposed droop-controlled HVDC networks that cover a wide geographical area require communication between converters to update the droop coefficients. The reliance on the communication becomes a limiting factor in the development of MTDC networks.In this paper, we present a novel communication-less and cooperative dc voltage control technique fora multi-terminal HVDC transmission system that employs an Hinf controller for the voltage regulation.One grid side converter, called the master, and an offshore wind farm are designated to guarantee themain dc voltage stability as well as to maintain a power reserve for the provision of fast grid supportservices. A flexible main dc voltage level is maintained by the master converter to control the poweroutput and to indirectly signal to the wind farm to inject more or less power, hence no dedicated communication system is needed. An Hinf local dc voltage controller is designed to manage efficiently the reserve of power in the form of de-loaded wind turbines. The proposed controller acts on the blade pitch angle and guarantees the internal stability of the presented multi-terminal HVDC (MTDC) transmission system locally around an equilibrium (operating) point. The studied MTDC consists of three converter terminals, a master converter, a standard active/reactive power converter and an offshore wind farm.The effectiveness of the proposed control strategy is validated through preliminary simulation results inMATLAB-SIMULINK.

   Advanced Test Circuit for DC Circuit Breakers
By Tim AUGUSTIN [View]
[Download]

Abstract: In future HVDC systems, many DC circuit breakers (DCCBs) will be required. In this paper, an advancedtest circuit for DCCBs is described. A DC source is combined with a capacitor bank. In contrast to othertest circuits, the proposed test circuit allows to replicate constant DC and temporary faults. In additionto conventional faults, this enables testing of auto-reclosing, proactive commutation, and complex testsequences combining all of these modes. The test circuit is easy to setup and also suitable for smallerresearch facilities. Experimental results from a down-scaled mock-up are included to demonstrate thecapabilities of the test circuit.

   Gain Optimization for STATCOM Voltage Control under Various Grid Conditions
By Joachim STEINKOHL [View]
[Download]

Abstract: Static Compensators (STATCOMs) with voltage control are known for their fast reaction time to stabilizethe grid voltage. For optimal dynamic performance it is essential to adjust the gain settings for thevoltage controller, for different states of operation. This paper presents a new gain adaption algorithm topassively adapt to changes in the grid stiffness as well as to other dynamic voltage controlling devices,in order to provide stable STATCOM behavior in all system conditions. The proposed control will notneed communication between the FACTS units. Which consequently simplifies and enhances the controlsystems even under severe grid changes.

   Impedance-based DC Side Stability Assessment of VSC-HVDC Systems with Control Time Delay
By Thomas ROOSE [View]
[Download]

Abstract: In this paper, an impedance-based assessment is used to analyse the stability at the DC side of VSC-HVDC systems. The assessment applies the passivity theory and the Nyquist stability criterion on the frequency response obtained from the VSC-HVDC system. Via this method, it is possible to predict potential instability of a MMC-based VSC-HVDC link. Further, it is demonstrated that the control dynamics of the MMC causes regions of non-passivity at the kHz-range which can interaction in a undesirable way with the system resonances. A wideband model of the VSC-HVDC system is employed to accurately capture these unstable interactions. Hence, the averaged dynamic model and the frequency-dependent phase model of PSCAD/EMTDC are chosen for representing respectively the MMCs and the transmission lines. Both the stability of submarine cable and overhead line connected VSC-HVDC links are analysed and the impact of the connection type on the system stability is investigated. Finally, a comparison is made between the time domain simulation of the system and the result of the impedance-based stability assessment.

   Modeling and Control of the Modular Multilevel Converter connected to an inductive DC source using Energetic Macroscopic Representation
By Taoufik QORIA [View]
[Download]

Abstract: The use of DC transmission is particularly advantageous for long-distance transmission and interconnection of asynchronous AC networks. Several converter topologies can be used for HVDC. Multilevel Modular Converters (MMCs) are the most favored given their technological advantages over other converters topologies. Due to their industrial maturity, they have become essential for all AC / DC conversion. So far, they have always been studied with a voltage source on DC side. However, when the converter is equipped with DC breaker, a series inductor is associated to limit current variations. This has consequences in term of modeling and control determination. This article aims to propose a modification of the control law in order to take into account this inductor. To facilitate the control organization, the Energetic Macroscopic Representation (EMR) is used.

EPE 2018 - DS1f: HVDC and FACTS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 06: Grids, Smart Grids, AC & DC > EPE 2018 - DS1f: HVDC and FACTS
	[return to parent folder]

	A Communication-less Cooperative dc Voltage Control Technique for a Multi-terminal HVDC Transmission System using Hinf Control By Roberto SANDANO	[View] [Download]
Abstract: New and upcoming regulations are requiring converters in high voltage direct current (HVDC) connections to be able provide a rapid response to support the stability of the main synchronous network to which they are connected. However, currently proposed droop-controlled HVDC networks that cover a wide geographical area require communication between converters to update the droop coefficients. The reliance on the communication becomes a limiting factor in the development of MTDC networks.In this paper, we present a novel communication-less and cooperative dc voltage control technique fora multi-terminal HVDC transmission system that employs an Hinf controller for the voltage regulation.One grid side converter, called the master, and an offshore wind farm are designated to guarantee themain dc voltage stability as well as to maintain a power reserve for the provision of fast grid supportservices. A flexible main dc voltage level is maintained by the master converter to control the poweroutput and to indirectly signal to the wind farm to inject more or less power, hence no dedicated communication system is needed. An Hinf local dc voltage controller is designed to manage efficiently the reserve of power in the form of de-loaded wind turbines. The proposed controller acts on the blade pitch angle and guarantees the internal stability of the presented multi-terminal HVDC (MTDC) transmission system locally around an equilibrium (operating) point. The studied MTDC consists of three converter terminals, a master converter, a standard active/reactive power converter and an offshore wind farm.The effectiveness of the proposed control strategy is validated through preliminary simulation results inMATLAB-SIMULINK.

	Advanced Test Circuit for DC Circuit Breakers By Tim AUGUSTIN	[View] [Download]
Abstract: In future HVDC systems, many DC circuit breakers (DCCBs) will be required. In this paper, an advancedtest circuit for DCCBs is described. A DC source is combined with a capacitor bank. In contrast to othertest circuits, the proposed test circuit allows to replicate constant DC and temporary faults. In additionto conventional faults, this enables testing of auto-reclosing, proactive commutation, and complex testsequences combining all of these modes. The test circuit is easy to setup and also suitable for smallerresearch facilities. Experimental results from a down-scaled mock-up are included to demonstrate thecapabilities of the test circuit.

	Gain Optimization for STATCOM Voltage Control under Various Grid Conditions By Joachim STEINKOHL	[View] [Download]
Abstract: Static Compensators (STATCOMs) with voltage control are known for their fast reaction time to stabilizethe grid voltage. For optimal dynamic performance it is essential to adjust the gain settings for thevoltage controller, for different states of operation. This paper presents a new gain adaption algorithm topassively adapt to changes in the grid stiffness as well as to other dynamic voltage controlling devices,in order to provide stable STATCOM behavior in all system conditions. The proposed control will notneed communication between the FACTS units. Which consequently simplifies and enhances the controlsystems even under severe grid changes.

	Impedance-based DC Side Stability Assessment of VSC-HVDC Systems with Control Time Delay By Thomas ROOSE	[View] [Download]
Abstract: In this paper, an impedance-based assessment is used to analyse the stability at the DC side of VSC-HVDC systems. The assessment applies the passivity theory and the Nyquist stability criterion on the frequency response obtained from the VSC-HVDC system. Via this method, it is possible to predict potential instability of a MMC-based VSC-HVDC link. Further, it is demonstrated that the control dynamics of the MMC causes regions of non-passivity at the kHz-range which can interaction in a undesirable way with the system resonances. A wideband model of the VSC-HVDC system is employed to accurately capture these unstable interactions. Hence, the averaged dynamic model and the frequency-dependent phase model of PSCAD/EMTDC are chosen for representing respectively the MMCs and the transmission lines. Both the stability of submarine cable and overhead line connected VSC-HVDC links are analysed and the impact of the connection type on the system stability is investigated. Finally, a comparison is made between the time domain simulation of the system and the result of the impedance-based stability assessment.

	Modeling and Control of the Modular Multilevel Converter connected to an inductive DC source using Energetic Macroscopic Representation By Taoufik QORIA	[View] [Download]
Abstract: The use of DC transmission is particularly advantageous for long-distance transmission and interconnection of asynchronous AC networks. Several converter topologies can be used for HVDC. Multilevel Modular Converters (MMCs) are the most favored given their technological advantages over other converters topologies. Due to their industrial maturity, they have become essential for all AC / DC conversion. So far, they have always been studied with a voltage source on DC side. However, when the converter is equipped with DC breaker, a series inductor is associated to limit current variations. This has consequences in term of modeling and control determination. This article aims to propose a modification of the control law in order to take into account this inductor. To facilitate the control organization, the Energetic Macroscopic Representation (EMR) is used.