EPE Association: NORpie 2006 - Topic 11: Distributed Generation

NORpie 2006 - Topic 11: Distributed Generation
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   Studying the protection impacts of distributed generation using network planning systems
By K. Mäki; S. Repo; P. Järventausta [View]
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Abstract: The penetration of distributed generation sets new requirements for the electrical distribution network. The network has traditionally been a passive component with assumed ‘downwards’ power flow. Distributed generation changes the basis of network operation and planning. A safe and reliable usage of the network requires operational protection. The present protection schemes may prove nonfunctional in the presence of distributed generation. Managing the more complex protection system is one of the main challenges for the growth of distributed generation. The network planning is typically performed with dedicated planning systems. There is a need to develop these systems to include the impacts of distributed generation. This would enable effective planning activity as the grid integration of distributed generation becomes more common planning task.

   Two-level and Three-level Converter Comparison
By M. Ikonen; O. Laakkonen; M. Kettunen [View]
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Abstract: Frequency converters are used in wind turbines because they make it possible to apply the variable-speed concept. They also make it possible for wind farm to become active element in the power system. The traditional frequency converter is a back-to-back connected two-level converter, in which the output voltage has two possible values. However, the output voltage is smoother with a three-level converter, where output voltage has three possible values. This results in smaller harmonics, but on the other hand it has more components and is more complex to control. In this paper we study the different three-level converter topologies and make a cost and power loss comparison between the two-level and three-level converters assuming the same input voltage and switching frequency. The study is a part of a course called “Nordic PhD Course on Wind Power” which was held in Smöla, Norway at June 5th – 11th 2005.

   Real-time simulation environment for power system studies using RTDS and dSPACE simulators
By K. Mäki; A. Partanen; T. Rauhala; S. Repo; P. Järventausta; P. Parkatti; H. Tuusa [View]
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Abstract: The increasing amount of power electronics and distributed generation located in the electrical networks require accurate studies in the future. The power electronic and power system related studies are usually performed more or less separately. It can be seen that novel combined research environments could be useful. This paper presents first experiences on integrating RTDS (Real Time Digital Simulator) and dSPACE real-time simulators to one system for wide-scale studies. RTDS is a simulation tool for power system studies and dSPACE is a simulation tool for computer-aided control systems. Combining these systems could offer a suitable environment for studying the interactions between the power system and power electronic sides. The combined environment has been tested for studying active power filtering. The results obtained are also presented in this paper.

   Islanding and Reconnection of Converter Based Distributed Generation Systems
By P. Karlsson [View]
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Abstract: In this paper a method for reconnecting islanded distributed generation systems is presented. Islanding of a distributed generation system may result from a fault or malfunction of protective elements. The behavior of local voltage and frequency control in case of islanding is investigated. A method for reconnecting the distributed generation system and the behavior of voltage and frequency control in case of reconnection are also investigated. It is found that islanding and reconnection with preserved voltage and frequency control is possible also in the case of local control without communication. Still communication of low bandwidth is required for the reconnection scheme presented here. The method presented is verified in simulations.

NORpie 2006 - Topic 11: Distributed Generation
You are here: EPE Documents > 05 - EPE Supported Conference Proceedings > NORpie - Proceedings > NORpie 2006 > NORpie 2006 - Topic 11: Distributed Generation
	[return to parent folder]

	Studying the protection impacts of distributed generation using network planning systems By K. Mäki; S. Repo; P. Järventausta	[View] [Download]
Abstract: The penetration of distributed generation sets new requirements for the electrical distribution network. The network has traditionally been a passive component with assumed ‘downwards’ power flow. Distributed generation changes the basis of network operation and planning. A safe and reliable usage of the network requires operational protection. The present protection schemes may prove nonfunctional in the presence of distributed generation. Managing the more complex protection system is one of the main challenges for the growth of distributed generation. The network planning is typically performed with dedicated planning systems. There is a need to develop these systems to include the impacts of distributed generation. This would enable effective planning activity as the grid integration of distributed generation becomes more common planning task.

	Two-level and Three-level Converter Comparison By M. Ikonen; O. Laakkonen; M. Kettunen	[View] [Download]
Abstract: Frequency converters are used in wind turbines because they make it possible to apply the variable-speed concept. They also make it possible for wind farm to become active element in the power system. The traditional frequency converter is a back-to-back connected two-level converter, in which the output voltage has two possible values. However, the output voltage is smoother with a three-level converter, where output voltage has three possible values. This results in smaller harmonics, but on the other hand it has more components and is more complex to control. In this paper we study the different three-level converter topologies and make a cost and power loss comparison between the two-level and three-level converters assuming the same input voltage and switching frequency. The study is a part of a course called “Nordic PhD Course on Wind Power” which was held in Smöla, Norway at June 5th – 11th 2005.

	Real-time simulation environment for power system studies using RTDS and dSPACE simulators By K. Mäki; A. Partanen; T. Rauhala; S. Repo; P. Järventausta; P. Parkatti; H. Tuusa	[View] [Download]
Abstract: The increasing amount of power electronics and distributed generation located in the electrical networks require accurate studies in the future. The power electronic and power system related studies are usually performed more or less separately. It can be seen that novel combined research environments could be useful. This paper presents first experiences on integrating RTDS (Real Time Digital Simulator) and dSPACE real-time simulators to one system for wide-scale studies. RTDS is a simulation tool for power system studies and dSPACE is a simulation tool for computer-aided control systems. Combining these systems could offer a suitable environment for studying the interactions between the power system and power electronic sides. The combined environment has been tested for studying active power filtering. The results obtained are also presented in this paper.

	Islanding and Reconnection of Converter Based Distributed Generation Systems By P. Karlsson	[View] [Download]
Abstract: In this paper a method for reconnecting islanded distributed generation systems is presented. Islanding of a distributed generation system may result from a fault or malfunction of protective elements. The behavior of local voltage and frequency control in case of islanding is investigated. A method for reconnecting the distributed generation system and the behavior of voltage and frequency control in case of reconnection are also investigated. It is found that islanding and reconnection with preserved voltage and frequency control is possible also in the case of local control without communication. Still communication of low bandwidth is required for the reconnection scheme presented here. The method presented is verified in simulations.