EPE Association: EPE 2016 - DS3g: Renewable Energy Systems

EPE 2016 - DS3g: Renewable Energy Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 05: Renewable Energy Power Systems > EPE 2016 - DS3g: Renewable Energy Systems

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   Compatibility Analysis of Grid-connected Pico-hydro Systems using Conventional Photovoltaic Inverters
By Vicente LEITE [View]
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Abstract: Small scale hydropower has a considerable untapped potential, able to contribute to the increased energy demand. The integration of these systems into microgrids is an emerging solution for the electrification of remote areas and for self-sustainable power systems. This paper is devoted to the design optimization of grid-connected pico-hydro systems using conventional photovoltaic inverters, providing cost effective solutions able to explore a large amount of feasible sites. Experimental tests of the proposed innovative topology with two inverters and selected generators were performed, evaluating the performance in steady state and dynamic conditions, corroborate the proposed design procedure.

   Determination of Storage Loss Characteristics with Reasonable Measurement and Calculation Effort
By Thorsten VOGT [View]
[Download]

Abstract: This paper presents a method how to simply determine the losses of an energy storage depending on state of charge and actual power. The proposed method only requires the measurement of electrical quantities to determine the characteristic map and therefore can be implemented without need to modify of an existing electrical storage system. Exemplary results are shown of lithium-ion and lead-acid battery packs. The losses of the used lead-acid battery pack shows a clear dependency on the state of charge, mainly a quadratic dependency on the terminal power and a difference between charge and discharge. The lossesof the used lithium-ion battery packs shows in principle a similar result but with a much less significant dependency on the state of charge. The characteristic map of losses is useful to optimize the storage operation regarding minimal losses whenever a degree of freedom of the choice of storage power exists, e.g. in an energy management system of a microgrid for cost savings in the grid-coupled operation and longer back-up time in the island operation.

   Energy Management Optimization in Stand-Alone Power Supplies Using Online Estimation of Battery SOC
By MARIO CACCIATO [View]
[Download]

Abstract: With the aim to improve the energy management of battery packs in stand-alone power supply applications, a simple but effective model-based algorithm for battery state estimation has been developed. The method can be classified into the category of PI-based observers and exploits a Thevenin-based equivalent circuit to model the battery behavior associated with a simple start-up identification process. The algorithm provides a real-time accurate SOC estimation which can be used to evaluate the actual power capability and to predict the amount of energy flows in a long term time horizon. Moreover, useful information about battery aging such as SOH value can be obtained.Thanks to its straightforward implementation, the proposed algorithm can be conveniently integrated in the battery management systems of charge regulators and other power converters which are part of stand-alone power supplies. In such a way, it is possible to increase the harvested energy without increase the hardware requirements. A comprehensive validation has been carried out by performing several experimental comparisons between the battery state estimation performed by suggested approach and standard methods.

   Energy Storage in Drive Systems of Servo Presses for Reduction of Peak Power and Energy Recovery
By Alexander PIERER [View]
[Download]

Abstract: The development approach for energy storage systems focuses on optimally sized capacitor modules to reduce peak power and to avoid energy recovery of production machines. Using servo presses as an example, the application of two different energy storage systems in the DC link is practically examined. A simulation model in Matlab/Simulink and a test stand of a servo press are proposed for representing the power flows between the mains supply, the electric drives and the storage systems. The description of forming machines and the behaviour of the electric components are used to control the amount of stored energy in a storage system and to influence the process regarding a reduction of peak power.

   FIGURES OF MERIT FOR THE EVALUATION OF REGENERATIVE POWER CONVERTERS
By SEBASTIAN MAESTRI [View]
[Download]

Abstract: In some applications, like those for particle accelerators and transfer lines, electromagnet loads operate in cycling mode i.e. absorbing or extracting energy from or to a power source. Built-in energy storage such as electrochemical capacitors can be used whose lifetime is heavily depended on the current ripple and depth of discharge. Moreover, the sizing of this storage element is a trade-off between power taken from the grid and energy stored. Additionally, the adopted power conversion structure and control strategy impact on such decision process. In this work, a number of topologies have been evaluated for these applications and the key metrics used to compare them. The proposed figures of merit are used through examples to highlight the trade-offs related with the choice of dc-bus regulation topology and control strategy.

   Modular Energy Conversion System Using a Novel Control Structure Based on a Simple Analogue System
By Dorin PETREUS [View]
[Download]

Abstract: This paper proposes a novel control topology which enables the setup of a low cost analogue systemleading to the implementation of a modular energy conversion system. The proposed system will bepresented from concept, through the design and implementation stages, and verified throughsimulation and experimental results.

   Online Impedance Spectroscopy Estimation of a Battery
By MINA ABEDI VARNOSFADERANI [View]
[Download]

Abstract: Electrochemical impedance spectroscopy (EIS) is a helpful tool to understand how a battery is behaving and how it degrades. One of the disadvantages is that it is typically an 'off-line' process. This paper investigates an alternative method of looking at impedance spectroscopy of a battery system while it is on-line and operational by manipulating the switching pattern of the dc-dc converter to generate low frequency harmonics in conjunction with the normal high frequency switching pattern to determine impedance in real time. However, this adds extra ripple on the inductor which needs to be included in the design calculations. The paper describes the methodology and presents some experimental results in conjunction with EIS results to illustrate the concept.

   Specific Energy Consumption of PEM Water Electrolysers In Atmospheric and Pressurised Conditions
By Joonas KOPONEN [View]
[Download]

Abstract: Power electronics enable the interconnection between renewable energy and electrolytic hydrogenproduction. At ambient conditions, the volumetric energy density of hydrogen is low, and thereforepressurisation is required. This paper studies the effect of the hydrogen outlet pressure from PEMelectrolysers on the specific energy consumption of water electrolyser systems.

EPE 2016 - DS3g: Renewable Energy Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 05: Renewable Energy Power Systems > EPE 2016 - DS3g: Renewable Energy Systems
	[return to parent folder]

	Compatibility Analysis of Grid-connected Pico-hydro Systems using Conventional Photovoltaic Inverters By Vicente LEITE	[View] [Download]
Abstract: Small scale hydropower has a considerable untapped potential, able to contribute to the increased energy demand. The integration of these systems into microgrids is an emerging solution for the electrification of remote areas and for self-sustainable power systems. This paper is devoted to the design optimization of grid-connected pico-hydro systems using conventional photovoltaic inverters, providing cost effective solutions able to explore a large amount of feasible sites. Experimental tests of the proposed innovative topology with two inverters and selected generators were performed, evaluating the performance in steady state and dynamic conditions, corroborate the proposed design procedure.

	Determination of Storage Loss Characteristics with Reasonable Measurement and Calculation Effort By Thorsten VOGT	[View] [Download]
Abstract: This paper presents a method how to simply determine the losses of an energy storage depending on state of charge and actual power. The proposed method only requires the measurement of electrical quantities to determine the characteristic map and therefore can be implemented without need to modify of an existing electrical storage system. Exemplary results are shown of lithium-ion and lead-acid battery packs. The losses of the used lead-acid battery pack shows a clear dependency on the state of charge, mainly a quadratic dependency on the terminal power and a difference between charge and discharge. The lossesof the used lithium-ion battery packs shows in principle a similar result but with a much less significant dependency on the state of charge. The characteristic map of losses is useful to optimize the storage operation regarding minimal losses whenever a degree of freedom of the choice of storage power exists, e.g. in an energy management system of a microgrid for cost savings in the grid-coupled operation and longer back-up time in the island operation.

	Energy Management Optimization in Stand-Alone Power Supplies Using Online Estimation of Battery SOC By MARIO CACCIATO	[View] [Download]
Abstract: With the aim to improve the energy management of battery packs in stand-alone power supply applications, a simple but effective model-based algorithm for battery state estimation has been developed. The method can be classified into the category of PI-based observers and exploits a Thevenin-based equivalent circuit to model the battery behavior associated with a simple start-up identification process. The algorithm provides a real-time accurate SOC estimation which can be used to evaluate the actual power capability and to predict the amount of energy flows in a long term time horizon. Moreover, useful information about battery aging such as SOH value can be obtained.Thanks to its straightforward implementation, the proposed algorithm can be conveniently integrated in the battery management systems of charge regulators and other power converters which are part of stand-alone power supplies. In such a way, it is possible to increase the harvested energy without increase the hardware requirements. A comprehensive validation has been carried out by performing several experimental comparisons between the battery state estimation performed by suggested approach and standard methods.

	Energy Storage in Drive Systems of Servo Presses for Reduction of Peak Power and Energy Recovery By Alexander PIERER	[View] [Download]
Abstract: The development approach for energy storage systems focuses on optimally sized capacitor modules to reduce peak power and to avoid energy recovery of production machines. Using servo presses as an example, the application of two different energy storage systems in the DC link is practically examined. A simulation model in Matlab/Simulink and a test stand of a servo press are proposed for representing the power flows between the mains supply, the electric drives and the storage systems. The description of forming machines and the behaviour of the electric components are used to control the amount of stored energy in a storage system and to influence the process regarding a reduction of peak power.

	FIGURES OF MERIT FOR THE EVALUATION OF REGENERATIVE POWER CONVERTERS By SEBASTIAN MAESTRI	[View] [Download]
Abstract: In some applications, like those for particle accelerators and transfer lines, electromagnet loads operate in cycling mode i.e. absorbing or extracting energy from or to a power source. Built-in energy storage such as electrochemical capacitors can be used whose lifetime is heavily depended on the current ripple and depth of discharge. Moreover, the sizing of this storage element is a trade-off between power taken from the grid and energy stored. Additionally, the adopted power conversion structure and control strategy impact on such decision process. In this work, a number of topologies have been evaluated for these applications and the key metrics used to compare them. The proposed figures of merit are used through examples to highlight the trade-offs related with the choice of dc-bus regulation topology and control strategy.

	Modular Energy Conversion System Using a Novel Control Structure Based on a Simple Analogue System By Dorin PETREUS	[View] [Download]
Abstract: This paper proposes a novel control topology which enables the setup of a low cost analogue systemleading to the implementation of a modular energy conversion system. The proposed system will bepresented from concept, through the design and implementation stages, and verified throughsimulation and experimental results.

	Online Impedance Spectroscopy Estimation of a Battery By MINA ABEDI VARNOSFADERANI	[View] [Download]
Abstract: Electrochemical impedance spectroscopy (EIS) is a helpful tool to understand how a battery is behaving and how it degrades. One of the disadvantages is that it is typically an 'off-line' process. This paper investigates an alternative method of looking at impedance spectroscopy of a battery system while it is on-line and operational by manipulating the switching pattern of the dc-dc converter to generate low frequency harmonics in conjunction with the normal high frequency switching pattern to determine impedance in real time. However, this adds extra ripple on the inductor which needs to be included in the design calculations. The paper describes the methodology and presents some experimental results in conjunction with EIS results to illustrate the concept.

	Specific Energy Consumption of PEM Water Electrolysers In Atmospheric and Pressurised Conditions By Joonas KOPONEN	[View] [Download]
Abstract: Power electronics enable the interconnection between renewable energy and electrolytic hydrogenproduction. At ambient conditions, the volumetric energy density of hydrogen is low, and thereforepressurisation is required. This paper studies the effect of the hydrogen outlet pressure from PEMelectrolysers on the specific energy consumption of water electrolyser systems.