EPE Association: EPE-PEMC 2008 - Topic: Power Electronics in Electrical Energy Generation, Transmission and Distribution

EPE-PEMC 2008 - Topic: Power Electronics in Electrical Energy Generation, Transmission and Distribution
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2008 - Conference > EPE-PEMC 2008 - Topic: Power Electronics in Electrical Energy Generation, Transmission and Distribution

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   A Comprehensive Analysis and Comparison Between Multilevel Space-Vector Modulation and Multilevel Carrier-Based PWM
By Constantinos Sourkounis [View]
[Download]

Abstract: This paper presents an analysis and a comparison of Multilevel three-phase Inverters based PWM modulators. Two different PWM strategies are used to turn on and off the switching devices, Multilevel Space Vector Modulation and Multilevel Carrier Based Modulation. The performance characteristics regarding the harmonic contents, switching losses and conduction losses have been computed. These characteristics have been determined for a 10KW. Three-level diode-clamped inverter supplying a 230 V, 11A, 4\% Inductive inner impedance of the grid through a simulation program to validate the proposed approaches.

   A Stand-Alone Photovoltaic Supercapacitor Battery Hybrid Energy Storage System
By M. E. Glavin, Paul K. W. Chan, S. Armstrong, and W. G. Hurley [View]
[Download]

Abstract: Most of the stand-alone photovoltaic (PV) systems require an energy storage buffer to supply continuous energy to the load when there is inadequate solar irradiation. Typically, Valve Regulated Lead Acid (VRLA) batteries are utilized for this application. However, supplying a large burst of current, such as motor startup, from the battery degrades battery plates, resulting in destruction of the battery. An alterative way of supplying large bursts of current is to combine VRLA batteries and supercapacitors to form a hybrid storage system, where the battery can supply continuous energy and the supercapacitor can supply the instant power to the load. In this paper, the role of the supercapacitor in a PV Energy Control Unit (ECU) is investigated by using Matlab/Simulink models. The ECU monitors and optimizes the power flow from the PV to the battery-supercapacitor hybrid and the load. Three different load conditions are studied, including a peak current load, pulsating current load and a constant current load. The simulation results show that the hybrid storage system can achieve higher specific power than the battery storage system.

   A Transformerless Interface Converter for a Distributed Generation System
By Tzung-Lin Lee [View]
[Download]

Abstract: Integrating various interface converters of smallrated distributed generators into the power system has become a promising solution to rapidly increasing demand of premium electric power. The output voltage of distributed generators, such as PVs, is usually so low that a low-frequency coupling transformer is required to place between the interface inverter and the grid for proper power delivery. However, this transformer may impede practical installation due to its large weight and size. This paper proposes a transformerless interface converter for a distributed generation system. Instead of the low-frequency transformer, a coupling capacitor is installed between the inverter and the grid to sustain a part of the fundamental voltage. By dynamically adjusting inverter output voltage vector, the power can be converted between the inverter and the grid without any low-frequency transformer. Based on this scheme, the lowvoltage generating source would be directly able to deliver available power into the high-voltage grid with unity power factor operation, or to supply reactive power for grid voltage regulation. The proposed method can also suppress power system harmonics due to its voltage control nature. Operation principles and design issues of the coupling capacitor are explained in detail, and computer simulation results are provided to validate the effectiveness of the proposed approach.

   Cascaded Doubly Fed Induction Generator for Mini and Micro Power Plants Connected to Grid
By Marek Adamowicz [View]
[Download]

Abstract: Mini hydropower and wind power plants have a promising future in Poland. Variable speed cascaded induction generators could be an attractive alternative to conventional double output induction generators habitually applied in mini hydropower stations. Cascaded induction generators require lower maintenance due the absence of slip rings and brushes. Unidirectional power converters can be employed in such power plants to provide simple power electronics, reduce of the maintenance and increase availability. Different topologies of rectifiers with a function of power factor correction could carry the slip power from the secondary side of the cascaded generator during the supersynchronous operation. The main benefit of these clean power rectifiers in comparison with diode rectifiers is the ability of canceling the torque harmonics of cascaded generator. The paper discuss which topology of clean power rectifiers could be applied as machine side rectifier in mini and micro power plants utilizing cascaded induction generator connected to grid.

   Contactless Power Transmission with New Secondary Converter Topology
By Matthias Dockhorn [View]
[Download]

Abstract: An innovative solution to slip rings and plug connectors is the contactless energy transmission system which is aligned to resonance. For an efficient energy transmission high frequencies (around 100 kHz) as well as an operation in resonance is useful. Some applications need a single-phase (50 Hz) supply A new energy conversion principle can be used to solve the problem. This paper describes a new converter topology and the development of the necessary control signals for the secondary and the primary circuit which provides a single-phase 50 Hz voltage on the secondary side without a need for a DC link. Moreover, practical tests and measurements are presented.

   Energy Storage Systems The Flywheel Energy Storage
By Tomasz Siostrzonek [View]
[Download]

Abstract: Storage of energy is one of the main problem of contemporary technology. Currently used manners of the energy store are listed below: The magnetic accumulator - the energy is kept in the magnetic field of superconductive inductor, The accumulator with supercapacitors. The low voltage (1,6-2,5 V) is the fault of this one, The accumulator with lead-acid or alkaline accumulator. The fault of this solution is very low charging and discharging efficiency, The electromechanical accumulator. Flywheels store Energy mechanically in the form of kinetic energy. In this article the flywheel energy storage will be described precisely and compared with other energystorage technologies.

   Identification of Electrical Parameters in a Power Network Using Genetic Algorithms and Transient Measurements
By Wei. Dong [View]
[Download]

Abstract: The knowledge of the parameter values of a power network is very valuable for power system modelling, simulation, protection and control since it is a fundamental parameter for solving many problems such as minimizing the effect of voltage distortion, active filter control or relay setting. The electrical parameters in a power network are usually unknown or poorly quantified and can not be measured directly. A new effective and reliable method for power network parameters identification based on voltage transient measurements using genetic algorithm optimization is successfully demonstrated. Simulation tests performed using Matlab-Simulink show the effectiveness of the proposed identification strategy.

   Integrated Contactless Power Transmission Systems with High Positioning Flexibility
By Daniel Kürschner and Christian Rathge [View]
[Download]

Abstract: Contactless power transmission provides the vision for the future development of energy distribution in industrial, business or consumer electronics or where a constructive conditional air gap must be bridged. By using the inductive technology, sliding contacts, trailing cables or slip rings can be eliminated and the safety and reliability of the energy supply can be improved. To design the transmission system, the paper presents a possibility to design the magnetic system by using analytical and numerical analyses. Based on special FEA models it is shown in the paper how to analyse and minimise the power loss of coil configurations. Furthermore it is shown how to reach a higher positioning flexibility of two coils of a resonant transmission system by optimising the coil parameters and the compensation technique. The paper presents two solutions of contactless transmission systems in the power range of 60 W and 1 kW and by means of an experimental set up the theoretical investigations are demonstrated by measurements.

   Modeling Approach of a Generator with Non-Linear Load in Embedded Electrical Network
By Nicolas Amelon [View]
[Download]

Abstract: This paper deals with a modeling approach of an embarked electrical network. This network is composed of a synchronous generator feeding linear and non linear load. In order to simplify the identification of inaccessible part of the generator, a specific modeling approach of the machine is established. Thus, the rotor is modeled by generalized transfer functions. Its order is chosen to have the desired accuracy and short computation time. Transfer function parameters can be easily identified by SSFR (StandStill Frequency Response) identification method. The generated model takes into account the strong interaction between all network components and variable topology of the non linear load. Some time domain simulation results are given in the end of the paper and illustrate the efficiency of this modeling approach.

   New Dual Channel Quasi Resonant DC-DC Converter Topologies for Distributed Energy Utilization
By J. Hamar [View]
[Download]

Abstract: The paper is concerned with new resonant converter configurations, belonging to the previously published dual channel dc-dc converter family. On one hand, the new configurations solve a significant shortcoming of the original ones, namely, the output midpoint potential was floating in comparison with the input midpoint. This caused a high-frequency oscillation of the output midpoint, often significantly limiting the application fields. Common ground can be used at the input and output sides at the new configurations. In addition, two of the new topologies also include electrical isolation, performed by an isolating highfrequency transformer. This property is often necessary in order to fulfill the strict industrial requirements against the power converters.

   On Acoustic Noise Reduction Procedure for Inverter-Fed Induction Machines
By Weiss Helmut [View]
[Download]

Abstract: Converter-fed variable speed drives are undesired sources of acoustic noise. Due to principle of operation magnetostriction and mechanical torque oscillations cause noise. For the prevailing variable speed realization through PMW inverter and induction machine mainly the machine with its outer components like cooling fins and ventilator hood can be the emitter of noise in audible area. Cooling fins practically shall stay metal material. Fan and fan hood favorably are from plastic material and could be made of composite material. Careful investigation of types of resonant bodies and their specific degree of freedom in mechanical resonant deformations help establish suitable designs for noise reduction. In addition, we shall take into consideration the advanced damping opportunities linked to composite material and the opportunity to define material stiffness parameters. This contribution provides a composite material based promising approach for efficient noise reduction.

   Optimal Use of the 14 V Alternator in 42 V Automotive Supply Systems
By Vasile Comnac [View]
[Download]

Abstract: This paper is aimed at the study of conventional 14 V automotive electrical supply systems as a basis for the development of a novel 42 V supply system capable to provide maximum power to both the vehicle's battery and the on-board consumers. By analyzing the operating characteristics of the 14 V Lundell alternator system, the conditions for maximum output power at various alternator driving speeds are determined. The modification of the conventional system by introducing a boost converter is proposed. The operating characteristics of the new system are analyzed by performing simulations using the MATLAB SIMULINK programming environment.

   Output Filtering of the Customer-end Inverter in a Low-Voltage DC Distribution Network
By Pasi Peltoniemi, Pasi Nuutinen, Pasi Salonen, Markku Niemelä and Juha Pyrhönen [View]
[Download]

Abstract: Passive filter topologies used at the output of the customer-end inverter in a low-voltage DC-distribution (LVDC) network are compared. The comparison of filter topologies is based on the requirements set for the voltage quality and issues such as the physical size of the filter, losses, the complexity of the needed control and the cost. It is concluded that most of the losses of LVDC system are coming from the customer-end filters. Therefore, to make the LVDC network as efficient as or even more efficient than the current three phase low voltage distribution network, filter topologies and their properties are evaluated. Because filters are used in distribution system, the cost and the losses have the governing roles. The study reveals the most suitable filter topology to be used in a LVDC distribution network, when using the specific properties presented.

   Power Flow Control through a Multi-Level H-Bridge based Power Converter for Universal and Flexible Power Management in Future Electrical Grids
By Stefano Bifaretti [View]
[Download]

Abstract: The paper proposes a novel power conversion system for Universal and Flexible Power Management (UNIFLEX-PM) in Future Electricity Network. The structure is based on three AC-DC converters each one connected to a different grid, (representing the main grid and/or various distributed generation systems) on the AC side, and linked together at DC side by suitable DC isolation modules. Each port of the UNIFLEX-PM system employs a conversion structure based on a three-phase 7-level AC-DC cascaded converter. Effective and accurate power flow control is demonstrated through simulation in Matlab and Simulink environment on a simplified model based on a two-port structure and using a Stationery Reference Frame based control solution. Control of different Power flow profiles has been successfully tested in numerous network conditions such as voltage unbalance, frequency excursions and harmonic distortion.

   Two-Level and Multilevel Converters for Wind Energy Systems: A Comparative Study
By R. Melício [View]
[Download]

Abstract: This paper is concerned with modeling and simulation of a wind energy system with different topologies for the power converters, namely a two-level converter and a multilevel converter. Pulse modulation by space vector modulation associated with sliding mode is used for controlling the converters, and power factor control is introduced at the output of the converters. Finally, a case study is presented, showing the electric behavior of the power and the current at the output of the converters and the direct voltage at the multilevel converter.

EPE-PEMC 2008 - Topic: Power Electronics in Electrical Energy Generation, Transmission and Distribution
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2008 - Conference > EPE-PEMC 2008 - Topic: Power Electronics in Electrical Energy Generation, Transmission and Distribution
	[return to parent folder]

	A Comprehensive Analysis and Comparison Between Multilevel Space-Vector Modulation and Multilevel Carrier-Based PWM By Constantinos Sourkounis	[View] [Download]
Abstract: This paper presents an analysis and a comparison of Multilevel three-phase Inverters based PWM modulators. Two different PWM strategies are used to turn on and off the switching devices, Multilevel Space Vector Modulation and Multilevel Carrier Based Modulation. The performance characteristics regarding the harmonic contents, switching losses and conduction losses have been computed. These characteristics have been determined for a 10KW. Three-level diode-clamped inverter supplying a 230 V, 11A, 4\% Inductive inner impedance of the grid through a simulation program to validate the proposed approaches.

	A Stand-Alone Photovoltaic Supercapacitor Battery Hybrid Energy Storage System By M. E. Glavin, Paul K. W. Chan, S. Armstrong, and W. G. Hurley	[View] [Download]
Abstract: Most of the stand-alone photovoltaic (PV) systems require an energy storage buffer to supply continuous energy to the load when there is inadequate solar irradiation. Typically, Valve Regulated Lead Acid (VRLA) batteries are utilized for this application. However, supplying a large burst of current, such as motor startup, from the battery degrades battery plates, resulting in destruction of the battery. An alterative way of supplying large bursts of current is to combine VRLA batteries and supercapacitors to form a hybrid storage system, where the battery can supply continuous energy and the supercapacitor can supply the instant power to the load. In this paper, the role of the supercapacitor in a PV Energy Control Unit (ECU) is investigated by using Matlab/Simulink models. The ECU monitors and optimizes the power flow from the PV to the battery-supercapacitor hybrid and the load. Three different load conditions are studied, including a peak current load, pulsating current load and a constant current load. The simulation results show that the hybrid storage system can achieve higher specific power than the battery storage system.

	A Transformerless Interface Converter for a Distributed Generation System By Tzung-Lin Lee	[View] [Download]
Abstract: Integrating various interface converters of smallrated distributed generators into the power system has become a promising solution to rapidly increasing demand of premium electric power. The output voltage of distributed generators, such as PVs, is usually so low that a low-frequency coupling transformer is required to place between the interface inverter and the grid for proper power delivery. However, this transformer may impede practical installation due to its large weight and size. This paper proposes a transformerless interface converter for a distributed generation system. Instead of the low-frequency transformer, a coupling capacitor is installed between the inverter and the grid to sustain a part of the fundamental voltage. By dynamically adjusting inverter output voltage vector, the power can be converted between the inverter and the grid without any low-frequency transformer. Based on this scheme, the lowvoltage generating source would be directly able to deliver available power into the high-voltage grid with unity power factor operation, or to supply reactive power for grid voltage regulation. The proposed method can also suppress power system harmonics due to its voltage control nature. Operation principles and design issues of the coupling capacitor are explained in detail, and computer simulation results are provided to validate the effectiveness of the proposed approach.

	Cascaded Doubly Fed Induction Generator for Mini and Micro Power Plants Connected to Grid By Marek Adamowicz	[View] [Download]
Abstract: Mini hydropower and wind power plants have a promising future in Poland. Variable speed cascaded induction generators could be an attractive alternative to conventional double output induction generators habitually applied in mini hydropower stations. Cascaded induction generators require lower maintenance due the absence of slip rings and brushes. Unidirectional power converters can be employed in such power plants to provide simple power electronics, reduce of the maintenance and increase availability. Different topologies of rectifiers with a function of power factor correction could carry the slip power from the secondary side of the cascaded generator during the supersynchronous operation. The main benefit of these clean power rectifiers in comparison with diode rectifiers is the ability of canceling the torque harmonics of cascaded generator. The paper discuss which topology of clean power rectifiers could be applied as machine side rectifier in mini and micro power plants utilizing cascaded induction generator connected to grid.

	Contactless Power Transmission with New Secondary Converter Topology By Matthias Dockhorn	[View] [Download]
Abstract: An innovative solution to slip rings and plug connectors is the contactless energy transmission system which is aligned to resonance. For an efficient energy transmission high frequencies (around 100 kHz) as well as an operation in resonance is useful. Some applications need a single-phase (50 Hz) supply A new energy conversion principle can be used to solve the problem. This paper describes a new converter topology and the development of the necessary control signals for the secondary and the primary circuit which provides a single-phase 50 Hz voltage on the secondary side without a need for a DC link. Moreover, practical tests and measurements are presented.

	Energy Storage Systems The Flywheel Energy Storage By Tomasz Siostrzonek	[View] [Download]
Abstract: Storage of energy is one of the main problem of contemporary technology. Currently used manners of the energy store are listed below: The magnetic accumulator - the energy is kept in the magnetic field of superconductive inductor, The accumulator with supercapacitors. The low voltage (1,6-2,5 V) is the fault of this one, The accumulator with lead-acid or alkaline accumulator. The fault of this solution is very low charging and discharging efficiency, The electromechanical accumulator. Flywheels store Energy mechanically in the form of kinetic energy. In this article the flywheel energy storage will be described precisely and compared with other energystorage technologies.

	Identification of Electrical Parameters in a Power Network Using Genetic Algorithms and Transient Measurements By Wei. Dong	[View] [Download]
Abstract: The knowledge of the parameter values of a power network is very valuable for power system modelling, simulation, protection and control since it is a fundamental parameter for solving many problems such as minimizing the effect of voltage distortion, active filter control or relay setting. The electrical parameters in a power network are usually unknown or poorly quantified and can not be measured directly. A new effective and reliable method for power network parameters identification based on voltage transient measurements using genetic algorithm optimization is successfully demonstrated. Simulation tests performed using Matlab-Simulink show the effectiveness of the proposed identification strategy.

	Integrated Contactless Power Transmission Systems with High Positioning Flexibility By Daniel Kürschner and Christian Rathge	[View] [Download]
Abstract: Contactless power transmission provides the vision for the future development of energy distribution in industrial, business or consumer electronics or where a constructive conditional air gap must be bridged. By using the inductive technology, sliding contacts, trailing cables or slip rings can be eliminated and the safety and reliability of the energy supply can be improved. To design the transmission system, the paper presents a possibility to design the magnetic system by using analytical and numerical analyses. Based on special FEA models it is shown in the paper how to analyse and minimise the power loss of coil configurations. Furthermore it is shown how to reach a higher positioning flexibility of two coils of a resonant transmission system by optimising the coil parameters and the compensation technique. The paper presents two solutions of contactless transmission systems in the power range of 60 W and 1 kW and by means of an experimental set up the theoretical investigations are demonstrated by measurements.

	Modeling Approach of a Generator with Non-Linear Load in Embedded Electrical Network By Nicolas Amelon	[View] [Download]
Abstract: This paper deals with a modeling approach of an embarked electrical network. This network is composed of a synchronous generator feeding linear and non linear load. In order to simplify the identification of inaccessible part of the generator, a specific modeling approach of the machine is established. Thus, the rotor is modeled by generalized transfer functions. Its order is chosen to have the desired accuracy and short computation time. Transfer function parameters can be easily identified by SSFR (StandStill Frequency Response) identification method. The generated model takes into account the strong interaction between all network components and variable topology of the non linear load. Some time domain simulation results are given in the end of the paper and illustrate the efficiency of this modeling approach.

	New Dual Channel Quasi Resonant DC-DC Converter Topologies for Distributed Energy Utilization By J. Hamar	[View] [Download]
Abstract: The paper is concerned with new resonant converter configurations, belonging to the previously published dual channel dc-dc converter family. On one hand, the new configurations solve a significant shortcoming of the original ones, namely, the output midpoint potential was floating in comparison with the input midpoint. This caused a high-frequency oscillation of the output midpoint, often significantly limiting the application fields. Common ground can be used at the input and output sides at the new configurations. In addition, two of the new topologies also include electrical isolation, performed by an isolating highfrequency transformer. This property is often necessary in order to fulfill the strict industrial requirements against the power converters.

	On Acoustic Noise Reduction Procedure for Inverter-Fed Induction Machines By Weiss Helmut	[View] [Download]
Abstract: Converter-fed variable speed drives are undesired sources of acoustic noise. Due to principle of operation magnetostriction and mechanical torque oscillations cause noise. For the prevailing variable speed realization through PMW inverter and induction machine mainly the machine with its outer components like cooling fins and ventilator hood can be the emitter of noise in audible area. Cooling fins practically shall stay metal material. Fan and fan hood favorably are from plastic material and could be made of composite material. Careful investigation of types of resonant bodies and their specific degree of freedom in mechanical resonant deformations help establish suitable designs for noise reduction. In addition, we shall take into consideration the advanced damping opportunities linked to composite material and the opportunity to define material stiffness parameters. This contribution provides a composite material based promising approach for efficient noise reduction.

	Optimal Use of the 14 V Alternator in 42 V Automotive Supply Systems By Vasile Comnac	[View] [Download]
Abstract: This paper is aimed at the study of conventional 14 V automotive electrical supply systems as a basis for the development of a novel 42 V supply system capable to provide maximum power to both the vehicle's battery and the on-board consumers. By analyzing the operating characteristics of the 14 V Lundell alternator system, the conditions for maximum output power at various alternator driving speeds are determined. The modification of the conventional system by introducing a boost converter is proposed. The operating characteristics of the new system are analyzed by performing simulations using the MATLAB SIMULINK programming environment.

	Output Filtering of the Customer-end Inverter in a Low-Voltage DC Distribution Network By Pasi Peltoniemi, Pasi Nuutinen, Pasi Salonen, Markku Niemelä and Juha Pyrhönen	[View] [Download]
Abstract: Passive filter topologies used at the output of the customer-end inverter in a low-voltage DC-distribution (LVDC) network are compared. The comparison of filter topologies is based on the requirements set for the voltage quality and issues such as the physical size of the filter, losses, the complexity of the needed control and the cost. It is concluded that most of the losses of LVDC system are coming from the customer-end filters. Therefore, to make the LVDC network as efficient as or even more efficient than the current three phase low voltage distribution network, filter topologies and their properties are evaluated. Because filters are used in distribution system, the cost and the losses have the governing roles. The study reveals the most suitable filter topology to be used in a LVDC distribution network, when using the specific properties presented.

	Power Flow Control through a Multi-Level H-Bridge based Power Converter for Universal and Flexible Power Management in Future Electrical Grids By Stefano Bifaretti	[View] [Download]
Abstract: The paper proposes a novel power conversion system for Universal and Flexible Power Management (UNIFLEX-PM) in Future Electricity Network. The structure is based on three AC-DC converters each one connected to a different grid, (representing the main grid and/or various distributed generation systems) on the AC side, and linked together at DC side by suitable DC isolation modules. Each port of the UNIFLEX-PM system employs a conversion structure based on a three-phase 7-level AC-DC cascaded converter. Effective and accurate power flow control is demonstrated through simulation in Matlab and Simulink environment on a simplified model based on a two-port structure and using a Stationery Reference Frame based control solution. Control of different Power flow profiles has been successfully tested in numerous network conditions such as voltage unbalance, frequency excursions and harmonic distortion.

	Two-Level and Multilevel Converters for Wind Energy Systems: A Comparative Study By R. Melício	[View] [Download]
Abstract: This paper is concerned with modeling and simulation of a wind energy system with different topologies for the power converters, namely a two-level converter and a multilevel converter. Pulse modulation by space vector modulation associated with sliding mode is used for controlling the converters, and power factor control is introduced at the output of the converters. Finally, a case study is presented, showing the electric behavior of the power and the current at the output of the converters and the direct voltage at the multilevel converter.