EPE Association: EPE 2015 - DS2g: Renewable Energy and Storage Systems

EPE 2015 - DS2g: Renewable Energy and Storage Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 05: Renewable Energy Power Systems > EPE 2015 - DS2g: Renewable Energy and Storage Systems

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   A Two-level SOC Balance Strategy for a Novel Hybrid Energy Storage Topology
By FENGQI CHANG [View]
[Download]

Abstract: A novel supercapacitor-battery hybrid energy storage topology is proposed. It has all the advantagesof modular multilevel converters but its cost is relatively lower. The paper also proposed a two-levelSOC balance strategy to realize SOC balance of batteries and supercapacitors in the whole system. Themethod composed of the balance strategy for branches and the strategy for SOC balance between phases.And experimental results verified the advantages of the topology and the effect of the proposedequalization method.

   Characteristics Comparison of Interleaved Inductor-Coupled Double Dual Boost Converters
By Haruka HATSUYADO [View]
[Download]

Abstract: Recently, low output voltage fuel cell (FC) stacks tend to be used because cell voltage balance control on the FC stacks with small number of series connections is easier than that on those with large number of series connections. In those situations, a boost converter with low input current ripple and high voltage boost ratio is required because large output current ripple in fuel cell degrades the fuel cell performance and lifetime. As one of such converters which meet those demands, an interleaved inductor-coupled double dual boost (IIDDB) converter has been proposed. This paper proposes two types of new IIDDB converters, which have two diodes added to the previously proposed IIDDB converter. In addition, the characteristics of each type of proposed IIDDB converters are compared in the experiments. As a result, it is shown that the converter in which diodes are connected between the input and output terminals of the coupled inductors in order to bypass the inductors can obtain highest boost ratio among the proposed converters at duty ratio of 0.5 in the switches.

   Comparison of High Power Non-Isolated Multilevel DC-DC Converters for Medium-Voltage Battery Storage Applications
By Milos STOJADINOVIC [View]
[Download]

Abstract: In this paper 4-level neutral-point-clamped (4L-NPC), 4-level flying-capacitor (4L-FC) and 4-level neutral-point-clamped Cuk (4L-NPC-Cuk) converter topologies for multilevel DC-DC buck-boost converter for medium-voltage battery storage applications are compared with respect to efficiency and power density. The comprehensive comparison is performed with multi domain models and optimization procedures. For the converters, pareto-fronts are calculated for different operating frequencies in order to find the optimal design with respect to the specified minimum efficiency.

   Control of a Solid Oxide Fuel Cell / Gas MicroTurbine hybrid system using a multilevel convertor
By Ionel VECHIU [View]
[Download]

Abstract: MicroGrids (MGs) are one of the most efficient ways to integrate the renewable energy sources in the rural areas. The biogas extracted from the organic waste, an often-unused renewable resource, can be electrically valorised through a Solid Oxide Fuel Cell / Gas MicroTurbine hybrid system. In order to preserve the high electrical efficiency obtained with this kind of hybrid system, its integration into à rural MG has been done using only a 3LNPC. The paper focuses on the control strategy designed in order to allows managing the power produced by the two separate sources to meet the power demand.Simulation and experimental results, with a Solid Oxide Fuel Cell / Gas MicroTurbine hybrid system emulator and a 3LNPC prototype connected to a MG experimental platform, confirm the feasibility of the investigated system.

   Design of a Bidirectional DC-DC Converter with High-Frequency Isolation for Battery Applications
By António MARTINS [View]
[Download]

Abstract: Battery charging and discharging requires a high-performance power electronics based converter interface namely with electrical isolation, high efficiency and fast dynamics. This paper analyses and discusses the battery interfacing using the dual active bridge with phase shift control for a bidirectional DC-DC converter. This converter typically integrates systems for vehicle to grid and grid to vehicle applications. The converter is designed and simulated and several aspects of its operation are discussed, namely the condition for zero-voltage switching. The presented experimental results allow to validate the correct design and operation in the two main conditions, in particular the bidirectional power flow in steady-state and dynamic conditions.

   Distributed Cooperative Control of Multi Flywheel Energy Storage System for Electrical Vehicle Fast Charging Stations
By BO SUN [View]
[Download]

Abstract: Plug-in electrical vehicles will play a critical role in future smart grid and sudden connection of electrical vehicles chargers may cause huge power-peaks with high slew-rates on grid. In order to cope with this issue, this paper applies a distributed cooperative control for fast charging station with dedicated paralleled flywheel-based energy storage system. The distributed DC-bus signaling method is employed in the power coordination of grid and flywheel converters, and a distributed secondary controller generates DC voltage correction term to adjust the local voltage set-point through a dynamic consensus based voltage observer by communicating with its neighbors. The control system can realize the power balancing and DC voltage regulation with low reliance on communications. Finally, real-time hardware-in-the-loop results have been reported in order to verify the feasibility of proposed approach.

   Effect of the MPPT and SOC Control of the Charge Controller in PV System
By Rodolfo DUFO-LOPEZ [View]
[Download]

Abstract: Advanced PWM charge controllers for lead-acid batteries of PV systems use state of charge (SOC)control and Maximum Power Point Tracking (MPPT). The simulation of the PV system and the effectof the SOC control and MPPT on its performance and on the batteries lifetime is shown.

   Extensive EIS Characterization of Commercially Available Lithium Polymer Battery Cell for Performance Modelling
By Tiberiu STANCIU [View]
[Download]

Abstract: Electrochemical Impedance Spectroscopy (EIS) has become a popular analytical technique for research anddevelopment of battery cells' chemistries, due to the established, high precision computer controlledequipment, that are capable of direct, on-line monitoring of performance parameters or degradation of anelectrochemical system. Used for Lithium-ion (Li-ion) batteries, this method allows for a fast and accurateassessment of the battery's impedance at any working point, without modifying the state of the battery.The influence of the operating conditions, state of charge (SOC) and temperature on the performance of acommercially available 53 Ah Lithium polymer battery cell, manufactured by Kokam Co. Ltd., isinvestigated in laboratory experiments, at its beginning of life, by means of EIS. A data fitting algorithm wasused to obtain the parameter values for the proposed equivalent electrical circuit, which was further selectedfor the development of an accurate EIS based performance model for the chosen Li-ion battery cell.

   Hybridization of electrical energy storage for intelligent integration of photovoltaics in electric networks
By Dhaker ABBES [View]
[Download]

Abstract: In this paper, a photovoltaic system with super capacitors and batteries hybrid storage connected to the grid has been studied. A smart supervision algorithm based on fuzzy logic has been successfully developed. In addition, contribution of storage hybridization on batteries longevity has been proved using rain-flow cumulative damage method.

   Lithium-ion battery model and experimental validation
By Alberto BERRUETA [View]
[Download]

Abstract: The development of an accurate battery model is essential for the design of any energy storage system and the power converter connected to it. This paper reports on an experimental charac-terization, modelling and validation of a commercial NMC lithium-ion battery with a rated volt-age of 133 V and a rated capacity of 40 Ah. It is a straightforward model, which can be used to predict the behaviour of the battery in realistic situations. For the purpose of parameters fitting, tests with the whole commercial battery pack have been performed, giving as a result a suitable model to predict the final performance of the system. This model is a useful tool to optimize the size of the battery needed in a specific application and to design other elements of the system as power converters or control strategies. Moreover, the methodology proposed in this paper can be used to develop models of other types of lithium-ion batteries. The characterization experiments are easily replicable and the proposed electric circuit is valid for other lithium-ion batteries.

   Measurement Results of a Modular Energy Storage System unevenly equipped with Lithium-Ion Batteries
By Markus SCHROEDER [View]
[Download]

Abstract: storage system (BESS) that is based on a modular multilevel cascade converter (MMCC). The MMCCwas unevenly equipped with lithium-ion batteries. The suggested concept of modular BESS wasclassified in the context of BESS based on modular converter topologies and was realized in ahardware-setup in laboratory. Therefore, different operation modes of the modular BESS weredefined. Four different steady operation points of the entire system were investigated and evaluated.Finally, a concept of an active battery management system (BMS) was proved. It was shown that amodular BESS unevenly equipped with batteries offers several opportunities for BESS applicationsparticularly with regard to the integration of different types of batteries into one single BESS.

   Practical Design Considerations of Cascaded Hybrid Battery Storage Systems
By Iain MOSLEY [View]
[Download]

Abstract: The high cost of batteries has led to investigations in using second-life ex-transportation batteries for grid support applications. Vehicle manufacturers currently all have different specifications for battery chemistry, arrangement of cells, capacity and voltage. With anticipated new developments in battery chemistry which could also affect these parameters, there are, as yet, no standards defining parameters in second life applications. To overcome issues relating to sizing and to prevent future obsolescence for the rest of the energy storage system, a cascaded topology with an operating envelope design approach has been used to connect together modules. This topology offers advantages in terms of system reliability. The design methodology is validated through a set of experimental results resulting in the creation of surface maps looking at the operation of the converter (efficiency and inductor ripple current). The use of a pre-defined module operating envelope also offers advantages for developing new operational strategies for systems with both hybrid battery energy systems and also hybrid systems including other energy sources such as solar power.

   Stable Startup of Seamless Controlled Parallel Bidirectional DC/DC Converter
By Takayuki OUCHI [View]
[Download]

Abstract: A smart control method for Bidirectional DC-DC Converter has been developed. Both charge and discharge with buck / boost mode transition are achieved by common control structure without mode judgment. This simple structure is also extended to a parallel system, and controls multiple output power for both directions. The function has some exceptional case at the period of start-up and stop, because introduced complementary switching flows unexpected reverse current. To avoid the unexpected reverse current, we introduced the selective disable function of complementary switching and achieved stable start and stop control. This improvement also equipped the system additional charge only operation. Improved control structure was evaluated at the four-parallel converter system.

   Systematic Evaluation of Modular Multilevel Converter Topologies for Battery Energy Storage Systems Based on Split Batteries
By Andre HILLERS [View]
[Download]

Abstract: The advent of the modular multilevel converter has spawned a new breed of battery energy storage systems, able to connect directly to the medium voltage grid without a mains transformer. This paper compares the three most prominent variants: The single-delta bridge-cell (SDBC), the single-star bridge-cell (SSBC) and the double-star chopper-cell (DSCC). The comparison is based on a pareto optimal design approach, respecting the trade-off between power conversion efficiency and size of the passive components, which present important driving factors of the overall system costs. To make the assessment fair, the total semiconductor die area is equalized among all candidates and the switching frequency is controlled such that the average switched power is equal for all three converters.

   Technology description and characterization of a low-cost flywheel for energy management in microgrids
By GUSTAVO NAVARRO [View]
[Download]

Abstract: This paper describes a modular, integrated and low-cost kinetic energy storage system (KESS), its electrical characterization as well as its future integration and operation in a microgrid within the scope of a project called MIRED-CON (Microgeneration with Renewable Sources and its control). This project aims to develop, using the power microgrid installed in the CEDER (Soria, Spain), an advanced metering and control infrastructure to improve the operation performance and efficiency of the distribution grid. Metallic flywheel and switched reluctance machine are chosen as energy storage device to provide stability to the microgrid, frequency regulation and power peak limitation, achieving a high performance in the grid operation. The KEES is integrated with a grid side converter (GSC) to connect to the A mains, providing extra functionality to the system. The combined operation of the proposed KESS together with photovoltaic (PV) panels, wind power generation and micro-pumped hydro energy storage (PHES) in the real application is analyzed by means of different simulations using MATLAB/Simulink software. Two operation modes are considered regarding the KESS: grid-connected mode (smoothing the power generation with renewables) and islanded mode (controlling the frequency and the voltage of the microgrid). Electrical characterization from experimental results are used by the central control unit to have information about the available power and energy in the device, thus improving the energy management in the real facility.

EPE 2015 - DS2g: Renewable Energy and Storage Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 05: Renewable Energy Power Systems > EPE 2015 - DS2g: Renewable Energy and Storage Systems
	[return to parent folder]

	A Two-level SOC Balance Strategy for a Novel Hybrid Energy Storage Topology By FENGQI CHANG	[View] [Download]
Abstract: A novel supercapacitor-battery hybrid energy storage topology is proposed. It has all the advantagesof modular multilevel converters but its cost is relatively lower. The paper also proposed a two-levelSOC balance strategy to realize SOC balance of batteries and supercapacitors in the whole system. Themethod composed of the balance strategy for branches and the strategy for SOC balance between phases.And experimental results verified the advantages of the topology and the effect of the proposedequalization method.

	Characteristics Comparison of Interleaved Inductor-Coupled Double Dual Boost Converters By Haruka HATSUYADO	[View] [Download]
Abstract: Recently, low output voltage fuel cell (FC) stacks tend to be used because cell voltage balance control on the FC stacks with small number of series connections is easier than that on those with large number of series connections. In those situations, a boost converter with low input current ripple and high voltage boost ratio is required because large output current ripple in fuel cell degrades the fuel cell performance and lifetime. As one of such converters which meet those demands, an interleaved inductor-coupled double dual boost (IIDDB) converter has been proposed. This paper proposes two types of new IIDDB converters, which have two diodes added to the previously proposed IIDDB converter. In addition, the characteristics of each type of proposed IIDDB converters are compared in the experiments. As a result, it is shown that the converter in which diodes are connected between the input and output terminals of the coupled inductors in order to bypass the inductors can obtain highest boost ratio among the proposed converters at duty ratio of 0.5 in the switches.

	Comparison of High Power Non-Isolated Multilevel DC-DC Converters for Medium-Voltage Battery Storage Applications By Milos STOJADINOVIC	[View] [Download]
Abstract: In this paper 4-level neutral-point-clamped (4L-NPC), 4-level flying-capacitor (4L-FC) and 4-level neutral-point-clamped Cuk (4L-NPC-Cuk) converter topologies for multilevel DC-DC buck-boost converter for medium-voltage battery storage applications are compared with respect to efficiency and power density. The comprehensive comparison is performed with multi domain models and optimization procedures. For the converters, pareto-fronts are calculated for different operating frequencies in order to find the optimal design with respect to the specified minimum efficiency.

	Control of a Solid Oxide Fuel Cell / Gas MicroTurbine hybrid system using a multilevel convertor By Ionel VECHIU	[View] [Download]
Abstract: MicroGrids (MGs) are one of the most efficient ways to integrate the renewable energy sources in the rural areas. The biogas extracted from the organic waste, an often-unused renewable resource, can be electrically valorised through a Solid Oxide Fuel Cell / Gas MicroTurbine hybrid system. In order to preserve the high electrical efficiency obtained with this kind of hybrid system, its integration into à rural MG has been done using only a 3LNPC. The paper focuses on the control strategy designed in order to allows managing the power produced by the two separate sources to meet the power demand.Simulation and experimental results, with a Solid Oxide Fuel Cell / Gas MicroTurbine hybrid system emulator and a 3LNPC prototype connected to a MG experimental platform, confirm the feasibility of the investigated system.

	Design of a Bidirectional DC-DC Converter with High-Frequency Isolation for Battery Applications By António MARTINS	[View] [Download]
Abstract: Battery charging and discharging requires a high-performance power electronics based converter interface namely with electrical isolation, high efficiency and fast dynamics. This paper analyses and discusses the battery interfacing using the dual active bridge with phase shift control for a bidirectional DC-DC converter. This converter typically integrates systems for vehicle to grid and grid to vehicle applications. The converter is designed and simulated and several aspects of its operation are discussed, namely the condition for zero-voltage switching. The presented experimental results allow to validate the correct design and operation in the two main conditions, in particular the bidirectional power flow in steady-state and dynamic conditions.

	Distributed Cooperative Control of Multi Flywheel Energy Storage System for Electrical Vehicle Fast Charging Stations By BO SUN	[View] [Download]
Abstract: Plug-in electrical vehicles will play a critical role in future smart grid and sudden connection of electrical vehicles chargers may cause huge power-peaks with high slew-rates on grid. In order to cope with this issue, this paper applies a distributed cooperative control for fast charging station with dedicated paralleled flywheel-based energy storage system. The distributed DC-bus signaling method is employed in the power coordination of grid and flywheel converters, and a distributed secondary controller generates DC voltage correction term to adjust the local voltage set-point through a dynamic consensus based voltage observer by communicating with its neighbors. The control system can realize the power balancing and DC voltage regulation with low reliance on communications. Finally, real-time hardware-in-the-loop results have been reported in order to verify the feasibility of proposed approach.

	Effect of the MPPT and SOC Control of the Charge Controller in PV System By Rodolfo DUFO-LOPEZ	[View] [Download]
Abstract: Advanced PWM charge controllers for lead-acid batteries of PV systems use state of charge (SOC)control and Maximum Power Point Tracking (MPPT). The simulation of the PV system and the effectof the SOC control and MPPT on its performance and on the batteries lifetime is shown.

	Extensive EIS Characterization of Commercially Available Lithium Polymer Battery Cell for Performance Modelling By Tiberiu STANCIU	[View] [Download]
Abstract: Electrochemical Impedance Spectroscopy (EIS) has become a popular analytical technique for research anddevelopment of battery cells' chemistries, due to the established, high precision computer controlledequipment, that are capable of direct, on-line monitoring of performance parameters or degradation of anelectrochemical system. Used for Lithium-ion (Li-ion) batteries, this method allows for a fast and accurateassessment of the battery's impedance at any working point, without modifying the state of the battery.The influence of the operating conditions, state of charge (SOC) and temperature on the performance of acommercially available 53 Ah Lithium polymer battery cell, manufactured by Kokam Co. Ltd., isinvestigated in laboratory experiments, at its beginning of life, by means of EIS. A data fitting algorithm wasused to obtain the parameter values for the proposed equivalent electrical circuit, which was further selectedfor the development of an accurate EIS based performance model for the chosen Li-ion battery cell.

	Hybridization of electrical energy storage for intelligent integration of photovoltaics in electric networks By Dhaker ABBES	[View] [Download]
Abstract: In this paper, a photovoltaic system with super capacitors and batteries hybrid storage connected to the grid has been studied. A smart supervision algorithm based on fuzzy logic has been successfully developed. In addition, contribution of storage hybridization on batteries longevity has been proved using rain-flow cumulative damage method.

	Lithium-ion battery model and experimental validation By Alberto BERRUETA	[View] [Download]
Abstract: The development of an accurate battery model is essential for the design of any energy storage system and the power converter connected to it. This paper reports on an experimental charac-terization, modelling and validation of a commercial NMC lithium-ion battery with a rated volt-age of 133 V and a rated capacity of 40 Ah. It is a straightforward model, which can be used to predict the behaviour of the battery in realistic situations. For the purpose of parameters fitting, tests with the whole commercial battery pack have been performed, giving as a result a suitable model to predict the final performance of the system. This model is a useful tool to optimize the size of the battery needed in a specific application and to design other elements of the system as power converters or control strategies. Moreover, the methodology proposed in this paper can be used to develop models of other types of lithium-ion batteries. The characterization experiments are easily replicable and the proposed electric circuit is valid for other lithium-ion batteries.

	Measurement Results of a Modular Energy Storage System unevenly equipped with Lithium-Ion Batteries By Markus SCHROEDER	[View] [Download]
Abstract: storage system (BESS) that is based on a modular multilevel cascade converter (MMCC). The MMCCwas unevenly equipped with lithium-ion batteries. The suggested concept of modular BESS wasclassified in the context of BESS based on modular converter topologies and was realized in ahardware-setup in laboratory. Therefore, different operation modes of the modular BESS weredefined. Four different steady operation points of the entire system were investigated and evaluated.Finally, a concept of an active battery management system (BMS) was proved. It was shown that amodular BESS unevenly equipped with batteries offers several opportunities for BESS applicationsparticularly with regard to the integration of different types of batteries into one single BESS.

	Practical Design Considerations of Cascaded Hybrid Battery Storage Systems By Iain MOSLEY	[View] [Download]
Abstract: The high cost of batteries has led to investigations in using second-life ex-transportation batteries for grid support applications. Vehicle manufacturers currently all have different specifications for battery chemistry, arrangement of cells, capacity and voltage. With anticipated new developments in battery chemistry which could also affect these parameters, there are, as yet, no standards defining parameters in second life applications. To overcome issues relating to sizing and to prevent future obsolescence for the rest of the energy storage system, a cascaded topology with an operating envelope design approach has been used to connect together modules. This topology offers advantages in terms of system reliability. The design methodology is validated through a set of experimental results resulting in the creation of surface maps looking at the operation of the converter (efficiency and inductor ripple current). The use of a pre-defined module operating envelope also offers advantages for developing new operational strategies for systems with both hybrid battery energy systems and also hybrid systems including other energy sources such as solar power.

	Stable Startup of Seamless Controlled Parallel Bidirectional DC/DC Converter By Takayuki OUCHI	[View] [Download]
Abstract: A smart control method for Bidirectional DC-DC Converter has been developed. Both charge and discharge with buck / boost mode transition are achieved by common control structure without mode judgment. This simple structure is also extended to a parallel system, and controls multiple output power for both directions. The function has some exceptional case at the period of start-up and stop, because introduced complementary switching flows unexpected reverse current. To avoid the unexpected reverse current, we introduced the selective disable function of complementary switching and achieved stable start and stop control. This improvement also equipped the system additional charge only operation. Improved control structure was evaluated at the four-parallel converter system.

	Systematic Evaluation of Modular Multilevel Converter Topologies for Battery Energy Storage Systems Based on Split Batteries By Andre HILLERS	[View] [Download]
Abstract: The advent of the modular multilevel converter has spawned a new breed of battery energy storage systems, able to connect directly to the medium voltage grid without a mains transformer. This paper compares the three most prominent variants: The single-delta bridge-cell (SDBC), the single-star bridge-cell (SSBC) and the double-star chopper-cell (DSCC). The comparison is based on a pareto optimal design approach, respecting the trade-off between power conversion efficiency and size of the passive components, which present important driving factors of the overall system costs. To make the assessment fair, the total semiconductor die area is equalized among all candidates and the switching frequency is controlled such that the average switched power is equal for all three converters.

	Technology description and characterization of a low-cost flywheel for energy management in microgrids By GUSTAVO NAVARRO	[View] [Download]
Abstract: This paper describes a modular, integrated and low-cost kinetic energy storage system (KESS), its electrical characterization as well as its future integration and operation in a microgrid within the scope of a project called MIRED-CON (Microgeneration with Renewable Sources and its control). This project aims to develop, using the power microgrid installed in the CEDER (Soria, Spain), an advanced metering and control infrastructure to improve the operation performance and efficiency of the distribution grid. Metallic flywheel and switched reluctance machine are chosen as energy storage device to provide stability to the microgrid, frequency regulation and power peak limitation, achieving a high performance in the grid operation. The KEES is integrated with a grid side converter (GSC) to connect to the A mains, providing extra functionality to the system. The combined operation of the proposed KESS together with photovoltaic (PV) panels, wind power generation and micro-pumped hydro energy storage (PHES) in the real application is analyzed by means of different simulations using MATLAB/Simulink software. Two operation modes are considered regarding the KESS: grid-connected mode (smoothing the power generation with renewables) and islanded mode (controlling the frequency and the voltage of the microgrid). Electrical characterization from experimental results are used by the central control unit to have information about the available power and energy in the device, thus improving the energy management in the real facility.