EPE Association: EPE 2005 - Topic 14-5b - DS: Integration of distributed generation systems with the grid

EPE 2005 - Topic 14-5b - DS: Integration of distributed generation systems with the grid
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2005 - Conference > EPE 2005 - Topic 14: POWER ELECTRONICS IN ELECTRICAL ENERGY GENERATING SYSTEMS > EPE 2005 - Topic 14-5b - DS: Integration of distributed generation systems with the grid

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   Combined power supply method for micro grid by use of several types of distributed power generation systems
By KUSAGAWA Shi; NUMATA Shigeo; YONEZU Takenori; BABA Jumpei; MASADA Eisuke; NITTA Tanzo; DENDA Atsushi; SUZUKI Satoshi [View]
[Download]

Abstract: A power control method to compensate power fluctuation of the load in the microgrid systems is proposed and discussed.Active power responses of several kinds of distributed power generation systems (DGs) such as gas engine, micro gas turbine etc., energy storage system, and load fluctuation of a site have been measured. Based on the measurements, combination control method for several kinds of DGs and an energy storage system has been made and experiments have been carried out by use of small scale micro grid model system. It is shown that the load fluctuation has been compensated by the proposed method.

   Local Compensation of Wind Energy Conversion System
By HOFMANN Wilfried; SINGER Amr [View]
[Download]

Abstract: As the demand for renewable energy increases, the role that offshore wind power plants play in generation will become more and more crucial. Permanent Magnet Salient Pole Synchronous machines connected to DC network provide an alternative to offshore wind power plants. Fixed excitation is the main drawback. External compensation is an attractive solution to this problem. This paper provides a comparison between different compensation methods applied to Permanent Magnet Salient Pole Synchronous Generator (PSG) at different excitation levels i.e. under-and over-excited. An analytical derivation of the increase in the electrical power resulting from different types of compensation is deduced. The calculation of the losses of the inverter and efficiency accompanied with each type of compensation are presented.

   Modelling and Control of Four Wires Voltage Source Inverter Under Unbalanced Voltage Condition for Hybrid Power System Applications
By VECHIU Ionel; DAKYO Brayima; CAMBLONG Haritza; TAPIA Gerardo; CUREA Octavian [View]
[Download]

Abstract: In this paper, the operation of three-phase, four-wire voltage source inverter (VSI) under unbalanced voltage conditions is investigated. The inverter is particularly interesting for the simultaneous supply of three-phase and single-phase loads in transformerless Hybrid Power System (HPS) application. A control strategy for the VSI based on the decomposition of the supply voltages and currents into instantaneous positive, negative and homopolar sequence components is described. The three sequences are controlled using two different rotating reference frame systems, so that the disturbance of the output voltage due to the load unbalances is eliminated. Simulation results are presented to verify the validity of the control strategy.

   Modelling and Simulation of a Doubly Fed Induction Generator for isolated Grid(1) Micro-Hydro Power station(2) in Variable Speed Turbine for equatorial medium
By RAMUZ Denis [View]
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Abstract: In this paper, the authors propose an approach with problems of electricity production in isolated sites in French Guiana. Indeed, the geographical context of French Guiana implies a concentration of the population on the littoral connected to the electrical national grid “EDF”( ), whereas population living in rural areas and in majority located at the edge of the rivers, are dedicated to their own means of production by using Power Diesel Generators or Photovoltaic systems.

   On DC Injection to AC Grids from Distributed Generation
By SAMUELSSON Olof; KARLSSON Per; GERTMAR Lars [View]
[Download]

Abstract: Distributed Generation, DG, introduces multi-generator grids and new modes of operation. DG will likely introduce power electronic, PE, converters on a large scale at the low- and medium-voltage levels. DC injection into the AC grid is a threat from grid-connected PE converters that are badly structured. Low DC currents in AC current are difficult to measure at those low levels decided in IEEE™1547 and discussed in other international working groups. Transformers and PE can be co-designed to eliminate DC injection. Modern adjustable-speed drives, ASDs, especially, those with active rectifiers, form a basis to discuss and solve issues of DC Injection to AC Grids from DG also named Distributed Energy Resources, DER or even DR. DC components from power electronics, embedded in Solar power, Wind power, Energy storage, Smart houses, Smart-office buildings, Own generators, etc. will give rise to grid-aspects like AC components give frequencies around the fundamental one. FMEA, Failure Mode and Effects Analysis, is judged to be a tool for further synthesis.

   Power System Emulation Using a Real Time, 145kW, Virtual Power System.
By ARMSTRONG Matthew; TURNER Stephen; JACK Alan; ATKINSON David [View]
[Download]

Abstract: The Virtual Power System is a real time, real power level, controllable sink/source used to emulate electrical machines and load systems connected to a system which requires testing. This can significantly aid in the development and testing of power systems. An earlier development, the Virtual Machine concentrated solely on the emulation of a low power (7.5kW) induction machine. However, the concept of power system emulation is particularly appropriate to higher power level applications, such as renewable energy systems. Therefore, this paper considers the development of a 145kW Virtual Power System. At higher power levels, however, semiconductor devices switch at slower rates. This has an impact upon the maximum pulse width modulation switching rate which may be applied to the power electronics, and in turn results in slower current control loop implementation. This paper investigates the performance achievable from a 145kW power system emulator.

   Stability of Voltage and Frequency Control in Distributed Generation Based on Parallel-Connected Converters Feeding Constant Power Loads
By STROeM Magnus; KARLSSON Per; BJOeRNSTEDT Johan [View]
[Download]

Abstract: In this paper stability and dynamic properties of voltage and frequency droop control of power electronic converters are investigated for a distributed generation system. Droop control is utilized to share active and reactive power among the source converters. The voltage and frequency controllers are designed so that stand-alone converter operation feeding constant power loads performs satisfactory. These controllers are adapted to mimic the behaviour of present rotating generators connected directly to the power system, for seam-less transfer between island and grid-connected modes of operation. Small-signal and switch-mode, time-domain simulation results of a three-converter distributed generation system facilitating stand-alone operation verify the operation. Experimental results of a three-converter stand-alone system are also included for verification.

   Supply Power Quality of a Micro Grid based on Distributed Generations in Relation with Power Converter Control
By MASADA Eisuke; OHSHIMA Masaaki; BABA Jumpei; KUSAGAWA Shinichi [View]
[Download]

Abstract: The installation of distributed generations (DGs) at demand end is much interested by customers along with the liberalization of electric power market and worldwide interest on utilization of renewable energy source (RES) etc. However, it is apprehensive that installation of a number of small-scale DGs (less than several tenth of kW) to the existing distribution network of power grid may cause voltage instability and deterioration of supply power quality to customers. To cope with these problems, a concept of Micro Grid, which integrates DGs and customers as an unit of network, and is operated independently from the power grid, is proposed and being verified with model systems.Most of DGs, such as micro gas turbines, gas engines and fuel cells, are interconnected to the ac power supply network for customers through power conversion systems (PCS). In such cases, their basic performances are different from the conventional rotating machine, and the interaction among them should not be neglected. The focus of this paper is to propose novel control schemes for PCS based DGs and rotating machines respectively to secure both of operational stability and supply power quality of a micro grid. The performances of the micro grid are verified by simulation studies.

   Variable inductor for voltage control improvement in distribution networks
By MORREN Johan; TONSO Matteo; DE HAAN Sjoerd W.H. [View]
[Download]

Abstract: With an increasing penetration of Distributed Generation (DG) deviations in the distribution network voltage may occur as a consequence of changes, and even reversal, of the power flow in the feeders. In high voltage networks the voltage is normally controlled through reactive power that causes an in-phase voltage component across the reactance of the line. In distribution networks the feasibility of voltage control with reactive power is limited due to the low X/R ratio. A solution is proposed, which is based onthe insertion of a controllable inductance in the feeder. In combination with reactive power support of the DG units the voltage can be controlled. The performance of the device is analysed and shown in several case studies.

EPE 2005 - Topic 14-5b - DS: Integration of distributed generation systems with the grid
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2005 - Conference > EPE 2005 - Topic 14: POWER ELECTRONICS IN ELECTRICAL ENERGY GENERATING SYSTEMS > EPE 2005 - Topic 14-5b - DS: Integration of distributed generation systems with the grid
	[return to parent folder]

	Combined power supply method for micro grid by use of several types of distributed power generation systems By KUSAGAWA Shi; NUMATA Shigeo; YONEZU Takenori; BABA Jumpei; MASADA Eisuke; NITTA Tanzo; DENDA Atsushi; SUZUKI Satoshi	[View] [Download]
Abstract: A power control method to compensate power fluctuation of the load in the microgrid systems is proposed and discussed.Active power responses of several kinds of distributed power generation systems (DGs) such as gas engine, micro gas turbine etc., energy storage system, and load fluctuation of a site have been measured. Based on the measurements, combination control method for several kinds of DGs and an energy storage system has been made and experiments have been carried out by use of small scale micro grid model system. It is shown that the load fluctuation has been compensated by the proposed method.

	Local Compensation of Wind Energy Conversion System By HOFMANN Wilfried; SINGER Amr	[View] [Download]
Abstract: As the demand for renewable energy increases, the role that offshore wind power plants play in generation will become more and more crucial. Permanent Magnet Salient Pole Synchronous machines connected to DC network provide an alternative to offshore wind power plants. Fixed excitation is the main drawback. External compensation is an attractive solution to this problem. This paper provides a comparison between different compensation methods applied to Permanent Magnet Salient Pole Synchronous Generator (PSG) at different excitation levels i.e. under-and over-excited. An analytical derivation of the increase in the electrical power resulting from different types of compensation is deduced. The calculation of the losses of the inverter and efficiency accompanied with each type of compensation are presented.

	Modelling and Control of Four Wires Voltage Source Inverter Under Unbalanced Voltage Condition for Hybrid Power System Applications By VECHIU Ionel; DAKYO Brayima; CAMBLONG Haritza; TAPIA Gerardo; CUREA Octavian	[View] [Download]
Abstract: In this paper, the operation of three-phase, four-wire voltage source inverter (VSI) under unbalanced voltage conditions is investigated. The inverter is particularly interesting for the simultaneous supply of three-phase and single-phase loads in transformerless Hybrid Power System (HPS) application. A control strategy for the VSI based on the decomposition of the supply voltages and currents into instantaneous positive, negative and homopolar sequence components is described. The three sequences are controlled using two different rotating reference frame systems, so that the disturbance of the output voltage due to the load unbalances is eliminated. Simulation results are presented to verify the validity of the control strategy.

	Modelling and Simulation of a Doubly Fed Induction Generator for isolated Grid(1) Micro-Hydro Power station(2) in Variable Speed Turbine for equatorial medium By RAMUZ Denis	[View] [Download]
Abstract: In this paper, the authors propose an approach with problems of electricity production in isolated sites in French Guiana. Indeed, the geographical context of French Guiana implies a concentration of the population on the littoral connected to the electrical national grid “EDF”( ), whereas population living in rural areas and in majority located at the edge of the rivers, are dedicated to their own means of production by using Power Diesel Generators or Photovoltaic systems.

	On DC Injection to AC Grids from Distributed Generation By SAMUELSSON Olof; KARLSSON Per; GERTMAR Lars	[View] [Download]
Abstract: Distributed Generation, DG, introduces multi-generator grids and new modes of operation. DG will likely introduce power electronic, PE, converters on a large scale at the low- and medium-voltage levels. DC injection into the AC grid is a threat from grid-connected PE converters that are badly structured. Low DC currents in AC current are difficult to measure at those low levels decided in IEEE™1547 and discussed in other international working groups. Transformers and PE can be co-designed to eliminate DC injection. Modern adjustable-speed drives, ASDs, especially, those with active rectifiers, form a basis to discuss and solve issues of DC Injection to AC Grids from DG also named Distributed Energy Resources, DER or even DR. DC components from power electronics, embedded in Solar power, Wind power, Energy storage, Smart houses, Smart-office buildings, Own generators, etc. will give rise to grid-aspects like AC components give frequencies around the fundamental one. FMEA, Failure Mode and Effects Analysis, is judged to be a tool for further synthesis.

	Power System Emulation Using a Real Time, 145kW, Virtual Power System. By ARMSTRONG Matthew; TURNER Stephen; JACK Alan; ATKINSON David	[View] [Download]
Abstract: The Virtual Power System is a real time, real power level, controllable sink/source used to emulate electrical machines and load systems connected to a system which requires testing. This can significantly aid in the development and testing of power systems. An earlier development, the Virtual Machine concentrated solely on the emulation of a low power (7.5kW) induction machine. However, the concept of power system emulation is particularly appropriate to higher power level applications, such as renewable energy systems. Therefore, this paper considers the development of a 145kW Virtual Power System. At higher power levels, however, semiconductor devices switch at slower rates. This has an impact upon the maximum pulse width modulation switching rate which may be applied to the power electronics, and in turn results in slower current control loop implementation. This paper investigates the performance achievable from a 145kW power system emulator.

	Stability of Voltage and Frequency Control in Distributed Generation Based on Parallel-Connected Converters Feeding Constant Power Loads By STROeM Magnus; KARLSSON Per; BJOeRNSTEDT Johan	[View] [Download]
Abstract: In this paper stability and dynamic properties of voltage and frequency droop control of power electronic converters are investigated for a distributed generation system. Droop control is utilized to share active and reactive power among the source converters. The voltage and frequency controllers are designed so that stand-alone converter operation feeding constant power loads performs satisfactory. These controllers are adapted to mimic the behaviour of present rotating generators connected directly to the power system, for seam-less transfer between island and grid-connected modes of operation. Small-signal and switch-mode, time-domain simulation results of a three-converter distributed generation system facilitating stand-alone operation verify the operation. Experimental results of a three-converter stand-alone system are also included for verification.

	Supply Power Quality of a Micro Grid based on Distributed Generations in Relation with Power Converter Control By MASADA Eisuke; OHSHIMA Masaaki; BABA Jumpei; KUSAGAWA Shinichi	[View] [Download]
Abstract: The installation of distributed generations (DGs) at demand end is much interested by customers along with the liberalization of electric power market and worldwide interest on utilization of renewable energy source (RES) etc. However, it is apprehensive that installation of a number of small-scale DGs (less than several tenth of kW) to the existing distribution network of power grid may cause voltage instability and deterioration of supply power quality to customers. To cope with these problems, a concept of Micro Grid, which integrates DGs and customers as an unit of network, and is operated independently from the power grid, is proposed and being verified with model systems.Most of DGs, such as micro gas turbines, gas engines and fuel cells, are interconnected to the ac power supply network for customers through power conversion systems (PCS). In such cases, their basic performances are different from the conventional rotating machine, and the interaction among them should not be neglected. The focus of this paper is to propose novel control schemes for PCS based DGs and rotating machines respectively to secure both of operational stability and supply power quality of a micro grid. The performances of the micro grid are verified by simulation studies.

	Variable inductor for voltage control improvement in distribution networks By MORREN Johan; TONSO Matteo; DE HAAN Sjoerd W.H.	[View] [Download]
Abstract: With an increasing penetration of Distributed Generation (DG) deviations in the distribution network voltage may occur as a consequence of changes, and even reversal, of the power flow in the feeders. In high voltage networks the voltage is normally controlled through reactive power that causes an in-phase voltage component across the reactance of the line. In distribution networks the feasibility of voltage control with reactive power is limited due to the low X/R ratio. A solution is proposed, which is based onthe insertion of a controllable inductance in the feeder. In combination with reactive power support of the DG units the voltage can be controlled. The performance of the device is analysed and shown in several case studies.