EPE Association: EPE-PEMC 2000 - Topic 06b: Renewable Energy Systems

EPE-PEMC 2000 - Topic 06b: Renewable Energy Systems
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2000 - Conference > EPE-PEMC 2000 - Topic 06: Power Electronics in Electrical Energy Generation, Transmission and Distribution > EPE-PEMC 2000 - Topic 06b: Renewable Energy Systems

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   A Full Bridge Isolated DC/DC Converter for Modular Photovoltaic Systems
By Mecke R., Fischer D., Reifenstahl U.* [View]
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Abstract: The direct conversion of solar radiation into electric current by means of photovoltaic cells is one of the most attractive opportunity of using renewable energy. The paper proposes a high efficient voltage regulated DC/DC converter, which can be used for modular photovoltaic systems with a common DC bus. The DC/DC converter consists of a phase-shifted controlled IGBT bridge, a high frequency transformer and a full bridge rectifier. The input voltage range is between 80 and 130 V, the output voltage is 650 V and the power range is about 2 kW. The power electronic circuit is investigated by simulation and experiment. A voltage controller for the third-order control loop is calculated. It ensures high-quality dynamic behaviour. The values of the passive power electronic components (DC link inductance, output capacity) depend on the voltage controller parameters.

   A Novel Frequency Controlled Supply of a Stand Alone Wind Turbine
By Negm M.M.M. [View]
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Abstract: This paper proposes a designed technique to generate controlled frequency supply from a stand-alone wind turbine. This technique is based on a controller by which the output power of the wind turbine is divided into two parts, the first part is considered to be constant power which is kept at a constant frequency, the second part has the remaining output power. These two parts are simultaneously generated by two induction generators connected to the same shaft driven by the wind turbine. The first induction generator generates the constant output power which feeds a critical load, while the second induction generator, which generates the remaining output power, is connected to a non-critical load through a three phase bridge converter. The non-critical load extracts any fluctuation of the output power of the wind turbine to keep constant shaft speed. The paper includes design of the three phase bridge converter and the associated firing circuit, PID- controller and the principle of the controlled system, as well as the performance and laboratory test results of the proposed technique.

   Islanding Protection of Microconverters for Photovoltaics
By Woyte A., Belmans R., Nijs J.* [View]
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Abstract: A major safety issue about grid-connected photovoltaics is to avoid non-intentional operation in islanding mode with the stiff distribution grid being tripped. This paper presents detailed measurements on the islanding behaviour of four module inverters with maximum 200 W rated power. Although applying active anti-islanding measures, each inverter could be forced into islanding operation. It could be observed experimentally what recently has been shown analytically, that the so-called active frequency drift method against islanding fails if inverters are loaded with considerable parallel capacitance. As most distribution grids contain a considerable capacitance, improved methods are to be developed. One of the tested inverters failed totally what illustrates the need for standardised type approvals. In general, the outcomes contribute to identify several drawbacks in state-of-the-art technology to be discussed with the manufacturers.

EPE-PEMC 2000 - Topic 06b: Renewable Energy Systems
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2000 - Conference > EPE-PEMC 2000 - Topic 06: Power Electronics in Electrical Energy Generation, Transmission and Distribution > EPE-PEMC 2000 - Topic 06b: Renewable Energy Systems
	[return to parent folder]

	A Full Bridge Isolated DC/DC Converter for Modular Photovoltaic Systems By Mecke R., Fischer D., Reifenstahl U.*	[View] [Download]
Abstract: The direct conversion of solar radiation into electric current by means of photovoltaic cells is one of the most attractive opportunity of using renewable energy. The paper proposes a high efficient voltage regulated DC/DC converter, which can be used for modular photovoltaic systems with a common DC bus. The DC/DC converter consists of a phase-shifted controlled IGBT bridge, a high frequency transformer and a full bridge rectifier. The input voltage range is between 80 and 130 V, the output voltage is 650 V and the power range is about 2 kW. The power electronic circuit is investigated by simulation and experiment. A voltage controller for the third-order control loop is calculated. It ensures high-quality dynamic behaviour. The values of the passive power electronic components (DC link inductance, output capacity) depend on the voltage controller parameters.

	A Novel Frequency Controlled Supply of a Stand Alone Wind Turbine By Negm M.M.M.	[View] [Download]
Abstract: This paper proposes a designed technique to generate controlled frequency supply from a stand-alone wind turbine. This technique is based on a controller by which the output power of the wind turbine is divided into two parts, the first part is considered to be constant power which is kept at a constant frequency, the second part has the remaining output power. These two parts are simultaneously generated by two induction generators connected to the same shaft driven by the wind turbine. The first induction generator generates the constant output power which feeds a critical load, while the second induction generator, which generates the remaining output power, is connected to a non-critical load through a three phase bridge converter. The non-critical load extracts any fluctuation of the output power of the wind turbine to keep constant shaft speed. The paper includes design of the three phase bridge converter and the associated firing circuit, PID- controller and the principle of the controlled system, as well as the performance and laboratory test results of the proposed technique.

	Islanding Protection of Microconverters for Photovoltaics By Woyte A., Belmans R., Nijs J.*	[View] [Download]
Abstract: A major safety issue about grid-connected photovoltaics is to avoid non-intentional operation in islanding mode with the stiff distribution grid being tripped. This paper presents detailed measurements on the islanding behaviour of four module inverters with maximum 200 W rated power. Although applying active anti-islanding measures, each inverter could be forced into islanding operation. It could be observed experimentally what recently has been shown analytically, that the so-called active frequency drift method against islanding fails if inverters are loaded with considerable parallel capacitance. As most distribution grids contain a considerable capacitance, improved methods are to be developed. One of the tested inverters failed totally what illustrates the need for standardised type approvals. In general, the outcomes contribute to identify several drawbacks in state-of-the-art technology to be discussed with the manufacturers.