EPE Association: EPE-PEMC 2000 - Topic 06d: Flexible AC Transmission Systems

EPE-PEMC 2000 - Topic 06d: Flexible AC Transmission 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 06d: Flexible AC Transmission Systems

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   A HVIGBT Active Front End Converter in a 25 MW Rotating System Tie Frequency Converter
By Schmidhofer A., Weiss H., Ebner P. [View]
[Download]

Abstract: The new generation of the high-voltage insulated gate bipolar transistors (HVIGBT) with high current carrying capabilities makes feasible high power applications with an improved performance and higher reliability for power conversion. For the power supply of the variable-frequency railway network rotating system tie frequency converters with the rated power range of 20 up to 50 MW are used. A rotating system tie frequency converter consists of a slip ring induction machine, which has to be rated only for the slip power (less than 5 % of the rated transfer power) on the rotor side. The new proposed concept of a rotating system tie frequency converter with the rated power of 25 MW, in general to be found in power delivering for the German, Swiss and Austrian railway organisation, has an Active Front End (AFE) converter with HVIGBT as a voltage source DC-link converter. Power circuit, power transfer under steady-state and transient conditions and the running up procedure are described.

   Application of Unified Power Flow Controller for Power Quality Control
By Suzuki S., Baba J., Shutoh K., Masada E. [View]
[Download]

Abstract: This paper describes the control scheme and characteristics of the UPFC (the Unified Power Flow Controller) installed at a substation near the end of customer side, which is utilized to improve the power quality at demand side by power conditionings. The control scheme of UPFC is derived from an equivalent circuit model of the fundamental frequency on the basis of power flow. Its effectiveness is verified with simulation studies with PSCAD/EMTDC, against short interruption of the transmission line, reactive power flow control and suppression of harmonic distortion caused by loads. UPFC is concluded to be usefully installed at the demand side for the power quality control purpose of the load.

   Balancing the DC Link at the 3-level PWM System-Tie Frequency Converter Gebersdorf (Nuremberg)
By Drogsler O., Pichler P., Weiss H. [View]
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Abstract: 3-level PWM systems offer high power capabilities at reasonable current ratings. A fully static system-tie frequency converter with 15 (respect. 18) MVA at 16 2/3 Hz started to operate for the German railways (DB) in Muldenstein in 1994 [1], in 1996 it has been transferred to Gebersdorf. As all of its 56 controlled semiconductors for power transfer are GTOs (active front end at the 50 Hz side) the balance between the positive and the negative DC-link voltage at this 3-level-system has to be maintained by proper firing control of the GTOs. In the short intermediate steps of the PWM voltage - when only the positive or the negative DC-link capacitor is in the current path - an unsymmetry of the DC-link may occur or can be corrected. This contribution describes the method of balancing the DC-link of a 3-level PWM with the given output currents at arbitrary phase shifts.

   Unified Method and System for Power Generation
By Járdán R.K., Nagy I., Masada E.*, Nitta T.**, Ohsaki H.** [View]
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Abstract: The possibilities of further application of a system developed for producing electrical and heat energy from low pressure saturated or overheated steam or some other working medium is presented in the paper. The system consists of a high-speed turbine, coupled to a three-phase permanent magnet synchronous generator, a three-phase AC/AC converter and a microprocessor supervisory control unit. The original purpose of the system was to reduce the pressure of the working medium by a turbine instead of applying throttling valves thus producing mechanical and electric energy, that can be utilised directly to supply loads in stand-alone mode or feeding it back to existing utility mains. In the latter case the converter connected in parallel to the mains can serve also as a source of reactive power and a compensator of higher harmonic current components. A possible application as UPS is also considered. The basic system can be applied in a much wider field if other sources of primary energy carriers, such as alternative renewable and waste energy sources, are taken into account. Details of the technical solution, an overview of possible applications and various control strategies are also described in the paper.

   VSI Converters in Adjustable Speed Hydro Generators Utilised as FACTS Components
By Nestli T.F., Skullerud T.*, Nysveen A.* [View]
[Download]

Abstract: By replacing the normally DC excited rotor of a synchronous generator with three phase AC-windings, low-frequency currents can be injected, via slip rings, to excite the generator. This allows the rotational speed of the generator to deviate from the synchronous speed. The ability to run at non-synchronous speeds gives a potential to significantly increase the overall efficiency of a hydro power station, especially for pumped-storage plants. In addition, the frequency converter gives the opportunity, by accelerating or decelerating the rotor, to absorb or supply active peak-power from or to the grid. This can give a significant contribution to power system stability in case of fault situa-tions. In addition, the independent reactive power production made possible if a VSI is used in stead of a cycloconverter makes the unit an integrated reactive power compensator. The adjustable speed hydro generator can therefore be used not only to increase power station efficiency, but also as a FACTS component with active as well as reactive power control capabilities.

EPE-PEMC 2000 - Topic 06d: Flexible AC Transmission 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 06d: Flexible AC Transmission Systems
	[return to parent folder]

	A HVIGBT Active Front End Converter in a 25 MW Rotating System Tie Frequency Converter By Schmidhofer A., Weiss H., Ebner P.	[View] [Download]
Abstract: The new generation of the high-voltage insulated gate bipolar transistors (HVIGBT) with high current carrying capabilities makes feasible high power applications with an improved performance and higher reliability for power conversion. For the power supply of the variable-frequency railway network rotating system tie frequency converters with the rated power range of 20 up to 50 MW are used. A rotating system tie frequency converter consists of a slip ring induction machine, which has to be rated only for the slip power (less than 5 % of the rated transfer power) on the rotor side. The new proposed concept of a rotating system tie frequency converter with the rated power of 25 MW, in general to be found in power delivering for the German, Swiss and Austrian railway organisation, has an Active Front End (AFE) converter with HVIGBT as a voltage source DC-link converter. Power circuit, power transfer under steady-state and transient conditions and the running up procedure are described.

	Application of Unified Power Flow Controller for Power Quality Control By Suzuki S., Baba J., Shutoh K., Masada E.	[View] [Download]
Abstract: This paper describes the control scheme and characteristics of the UPFC (the Unified Power Flow Controller) installed at a substation near the end of customer side, which is utilized to improve the power quality at demand side by power conditionings. The control scheme of UPFC is derived from an equivalent circuit model of the fundamental frequency on the basis of power flow. Its effectiveness is verified with simulation studies with PSCAD/EMTDC, against short interruption of the transmission line, reactive power flow control and suppression of harmonic distortion caused by loads. UPFC is concluded to be usefully installed at the demand side for the power quality control purpose of the load.

	Balancing the DC Link at the 3-level PWM System-Tie Frequency Converter Gebersdorf (Nuremberg) By Drogsler O., Pichler P., Weiss H.	[View] [Download]
Abstract: 3-level PWM systems offer high power capabilities at reasonable current ratings. A fully static system-tie frequency converter with 15 (respect. 18) MVA at 16 2/3 Hz started to operate for the German railways (DB) in Muldenstein in 1994 [1], in 1996 it has been transferred to Gebersdorf. As all of its 56 controlled semiconductors for power transfer are GTOs (active front end at the 50 Hz side) the balance between the positive and the negative DC-link voltage at this 3-level-system has to be maintained by proper firing control of the GTOs. In the short intermediate steps of the PWM voltage - when only the positive or the negative DC-link capacitor is in the current path - an unsymmetry of the DC-link may occur or can be corrected. This contribution describes the method of balancing the DC-link of a 3-level PWM with the given output currents at arbitrary phase shifts.

	Unified Method and System for Power Generation By Járdán R.K., Nagy I., Masada E., Nitta T., Ohsaki H.*	[View] [Download]
Abstract: The possibilities of further application of a system developed for producing electrical and heat energy from low pressure saturated or overheated steam or some other working medium is presented in the paper. The system consists of a high-speed turbine, coupled to a three-phase permanent magnet synchronous generator, a three-phase AC/AC converter and a microprocessor supervisory control unit. The original purpose of the system was to reduce the pressure of the working medium by a turbine instead of applying throttling valves thus producing mechanical and electric energy, that can be utilised directly to supply loads in stand-alone mode or feeding it back to existing utility mains. In the latter case the converter connected in parallel to the mains can serve also as a source of reactive power and a compensator of higher harmonic current components. A possible application as UPS is also considered. The basic system can be applied in a much wider field if other sources of primary energy carriers, such as alternative renewable and waste energy sources, are taken into account. Details of the technical solution, an overview of possible applications and various control strategies are also described in the paper.

	VSI Converters in Adjustable Speed Hydro Generators Utilised as FACTS Components By Nestli T.F., Skullerud T., Nysveen A.	[View] [Download]
Abstract: By replacing the normally DC excited rotor of a synchronous generator with three phase AC-windings, low-frequency currents can be injected, via slip rings, to excite the generator. This allows the rotational speed of the generator to deviate from the synchronous speed. The ability to run at non-synchronous speeds gives a potential to significantly increase the overall efficiency of a hydro power station, especially for pumped-storage plants. In addition, the frequency converter gives the opportunity, by accelerating or decelerating the rotor, to absorb or supply active peak-power from or to the grid. This can give a significant contribution to power system stability in case of fault situa-tions. In addition, the independent reactive power production made possible if a VSI is used in stead of a cycloconverter makes the unit an integrated reactive power compensator. The adjustable speed hydro generator can therefore be used not only to increase power station efficiency, but also as a FACTS component with active as well as reactive power control capabilities.