EPE Association: EPE 2018 - LS6b: Renewables in the Grid

EPE 2018 - LS6b: Renewables in the Grid
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 05: Renewable Energy Power Systems > EPE 2018 - LS6b: Renewables in the Grid

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   Coordinated AC Voltage Sensorless Control Method For Multiple Inverters
By Tao XU [View]
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Abstract: AC voltage sensorless control method has been developed to reduce the inverter cost and improve the operational reliability. But it cannot guarantee the power control accuracy and may output the unwanted reactive power due to the accurate phase angle information absence of grid voltage. To overcome this significant disadvantage, this paper proposes a coordinated ac voltage sensorless control method for multiple inverters, which could be assumed for large-scale PV station, microgrid and etc. In specific, only one of multiple inverters would equip the ac voltage sensor and the rest will not install ac voltage sensors. Doing so, the proposed method can use the recently proposed global synchronous pulse width modulation method to distribute the calculated AC voltage information from the inverter with ac voltage sensor to those without ac voltage sensor for modifying the phase angles obtained by the traditional ac voltage sensorless control. The constructed experimental prototype verified the performance of the proposed method.

   Dynamic Behavior Emulation of Alkaline Electrolyzer by Power-Hardware-In-the-Loop
By Antti KOSONEN [View]
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Abstract: Hydrogen production is energy intensive, and hence, the efficiency of the process is essential. Power electronics play an important role in energy efficiency of water electrolyzers. In general, the research requires real devices and handling of hydrogen. On the other hand, the water electrolyzer stack can be replaced by a power hardware-in-the-loop (PHIL) emulator that includes the same electrical characteristics as the real one. However, water electrolyzers are dynamic devices, and hence, the PHIL emulator should be able to realize the same bandwidth. Dynamics are important when studying DC power quality effects on water electrolyzers. The switching phenomena that can be seen after the utilized rectification are up to several kHz in frequency. This paper examines a dynamic PHIL test system for the purpose of emulation of water electrolyzers.

   Rotating-Voltage-Vector Control for Wind Energy Plants providing Possibility for Ancillary Services
By Nastaran FAZLI [View]
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Abstract: The increasing number of decentralised regenerative feeders poses new challenges regarding a securegrid operation and grid stability. Until now, conventional power plants have taken on the task of providingancillary services to ensure the stability of the grid. These include the provision of instantaneous reserve,frequency-dependent provision of active power and voltage-dependent provision of reactive power, butalso island grid operation and grid restoration. Due to the shutdown of conventional power plants, thesetasks will increasingly also have to be offered by decentralised regenerative feeders.Compared to conventional power plants, converter-based regenerative feeders have no rotating massesor damping. Also, common current-based control methods require an existing grid for synchronisation.Therefore, the stated requirements cannot be fulfilled at all or only to a limited extent.In recent years, concepts have been developed that increasingly deal with this topic. Essential approacheshere are the emulation of the behaviour of synchronous machines in the control of converters and the useof voltage-based control methods. Thus, the decentralised regenerative feeders can also contribute togrid stability through virtual inertia and damping.This paper introduces a control approach that corresponds structurally to the common current-basedcontrol procedures of wind turbines. But in comparison, there is no need for a dedicated grid synchronisation.Furthermore, this approach has the inherent ability of island grid operation and black startcapability.

   Simplified Small-Signal Modelling of Grid-Connected Voltage Source Converters for Transient Grid Studies
By Florian HANS [View]
[Download]

Abstract: Distributed generation (DG) units increasingly become subject to grid codes requiring an active andreactive power control capability. Since voltage source converters (VSCs) represent a key componentin many DG units, accurate but simple models are crucial for analysing transient grid phenomena andto find adequate solutions that help to maintain a high power quality. This paper presents a simplifiedanalytical model of a grid-connected VSC, which covers the power flow from the primary energy source,over the DC link to the injected converter's output current for frequencies well below the converter'sswitching frequency. After modelling all relevant components of an open-loop power-controlled VSC,a model reduction is performed with special emphasis on the influence of DC link dynamics. Finally,the resulting model accuracy is validated and compared to its low-frequency approximation by means ofcomputer simulations and Bode plots, respectively.

EPE 2018 - LS6b: Renewables in the Grid
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2018 ECCE Europe - Conference > EPE 2018 - Topic 05: Renewable Energy Power Systems > EPE 2018 - LS6b: Renewables in the Grid
	[return to parent folder]

	Coordinated AC Voltage Sensorless Control Method For Multiple Inverters By Tao XU	[View] [Download]
Abstract: AC voltage sensorless control method has been developed to reduce the inverter cost and improve the operational reliability. But it cannot guarantee the power control accuracy and may output the unwanted reactive power due to the accurate phase angle information absence of grid voltage. To overcome this significant disadvantage, this paper proposes a coordinated ac voltage sensorless control method for multiple inverters, which could be assumed for large-scale PV station, microgrid and etc. In specific, only one of multiple inverters would equip the ac voltage sensor and the rest will not install ac voltage sensors. Doing so, the proposed method can use the recently proposed global synchronous pulse width modulation method to distribute the calculated AC voltage information from the inverter with ac voltage sensor to those without ac voltage sensor for modifying the phase angles obtained by the traditional ac voltage sensorless control. The constructed experimental prototype verified the performance of the proposed method.

	Dynamic Behavior Emulation of Alkaline Electrolyzer by Power-Hardware-In-the-Loop By Antti KOSONEN	[View] [Download]
Abstract: Hydrogen production is energy intensive, and hence, the efficiency of the process is essential. Power electronics play an important role in energy efficiency of water electrolyzers. In general, the research requires real devices and handling of hydrogen. On the other hand, the water electrolyzer stack can be replaced by a power hardware-in-the-loop (PHIL) emulator that includes the same electrical characteristics as the real one. However, water electrolyzers are dynamic devices, and hence, the PHIL emulator should be able to realize the same bandwidth. Dynamics are important when studying DC power quality effects on water electrolyzers. The switching phenomena that can be seen after the utilized rectification are up to several kHz in frequency. This paper examines a dynamic PHIL test system for the purpose of emulation of water electrolyzers.

	Rotating-Voltage-Vector Control for Wind Energy Plants providing Possibility for Ancillary Services By Nastaran FAZLI	[View] [Download]
Abstract: The increasing number of decentralised regenerative feeders poses new challenges regarding a securegrid operation and grid stability. Until now, conventional power plants have taken on the task of providingancillary services to ensure the stability of the grid. These include the provision of instantaneous reserve,frequency-dependent provision of active power and voltage-dependent provision of reactive power, butalso island grid operation and grid restoration. Due to the shutdown of conventional power plants, thesetasks will increasingly also have to be offered by decentralised regenerative feeders.Compared to conventional power plants, converter-based regenerative feeders have no rotating massesor damping. Also, common current-based control methods require an existing grid for synchronisation.Therefore, the stated requirements cannot be fulfilled at all or only to a limited extent.In recent years, concepts have been developed that increasingly deal with this topic. Essential approacheshere are the emulation of the behaviour of synchronous machines in the control of converters and the useof voltage-based control methods. Thus, the decentralised regenerative feeders can also contribute togrid stability through virtual inertia and damping.This paper introduces a control approach that corresponds structurally to the common current-basedcontrol procedures of wind turbines. But in comparison, there is no need for a dedicated grid synchronisation.Furthermore, this approach has the inherent ability of island grid operation and black startcapability.

	Simplified Small-Signal Modelling of Grid-Connected Voltage Source Converters for Transient Grid Studies By Florian HANS	[View] [Download]
Abstract: Distributed generation (DG) units increasingly become subject to grid codes requiring an active andreactive power control capability. Since voltage source converters (VSCs) represent a key componentin many DG units, accurate but simple models are crucial for analysing transient grid phenomena andto find adequate solutions that help to maintain a high power quality. This paper presents a simplifiedanalytical model of a grid-connected VSC, which covers the power flow from the primary energy source,over the DC link to the injected converter's output current for frequencies well below the converter'sswitching frequency. After modelling all relevant components of an open-loop power-controlled VSC,a model reduction is performed with special emphasis on the influence of DC link dynamics. Finally,the resulting model accuracy is validated and compared to its low-frequency approximation by means ofcomputer simulations and Bode plots, respectively.