Electric power conversion systems – Current conversion – With means to introduce or eliminate frequency components
Patent
1998-12-28
1999-12-07
Berhane, Adolf Deneke
Electric power conversion systems
Current conversion
With means to introduce or eliminate frequency components
363 51, H02M 114, H02H 700
Patent
active
059994223
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to control equipment for an active filter, connected to a dc circuit in a converter in an installation for transmission of high-voltage direct current.
BACKGROUND ART
For a general description of installations for transmission by means of high-voltage direct current, reference is made to J. Arillaga: High Voltage Direct Current Transmission, London 1988.
Examples of the use, design and connection of active filters in connection with such installations are given in W Zhang, G Asplund, A .ANG.berg, U Jonsson, O Loof: Active d. c. filter for HVDC system, ABB Review 1995, Nos. 6-7, pages 17-21, in L Gyugui, E. C. Sstrycula: Active AC Power Filters, IAS 76 Annual, pages 529-535, and in IEEE publication 89 WM 123-1 PWRD (IEEE/PES 1989 Winter Meeting, New York 1989): Cheuksum Wong, Ned Mohan, Selwyn E. Wright and Karl N. Mortensen: Feasibility Study of AC- and DC-Side Active Filters for HVDC Converter Terminals.
U.S. Pat. No. 5,296,764 describes a method for reduction of disturbances on an outgoing line from an electric power network by means of an active filter, the control order of which is formed in dependence on a control signal from a controlling device. This control signal is formed in dependence on the deviation of a current or a voltage, sensed in the power network, from a desired value, and is forwarded to the control order with such signs that the disturbances are reduced. According to the described method, the control signal is formed from the controlling device as a sequence of signal values, repeated with a certain periodicity corresponding to the periodicity for a source of disturbance in the power network. The feedback circuit comprises a filter which, at least within the frequency range of interest to the application, makes possible a linearization of the transfer function from the control signal of the controlling device to the deviation of the sensed current or voltage from the desired value, a compensation for non-minimum phase properties in the transfer function mentioned being included therein. By utilizing the periodicity of the disturbance source, a control circuit with negative feedback may, with good stability and damping, be implemented also for those applications where, for example, a long line is connected to the power network. The effort required for setting of parameters in the filter which compensates for the above-mentioned transfer function is, however, demanding and increases as a better approximation of the dynamic properties of the power network within the frequency range in question is aimed at. Further, switching operations in the power network lead to its transfer function being changed, and to this is to be added the fact that the frequency of the disturbance source is usually not completely stable.
An article in a periodical by C Tuttas: Anwendung aktiver Saugkreise in elektrischen Energieversorgungsnetzen, etzArchiv 1987, H.4, pages 93-100, describes a three-phase active filter for connection to an ac network for damping of resonances and certain definite harmonic currents in the network. A controlling unit for control of a filter current of a certain frequency .omega..sub.f comprises a comparison circuit for forming a control deviation between a sensed filter current and a reference value therefor. The control deviation, which is an ac signal of the form .DELTA.I*sin(.omega..sub.f t+.phi.) is converted, by multiplication by a signal of the form sin (.omega..sub.f t) and by a signal of the form cos (.omega..sub.f t) as well as by a current mean-value formation of the respective signals, obtained by the multiplications, into two components .DELTA.I.sub.sin =.DELTA.I*cos .phi. and .DELTA.I.sub.cos =.DELTA.I*sin .phi., respectively. These components, which thus are of the frequency zero, together contain information about the amplitude and phase position of the control deviation. Each one of these components is supplied to a respective controller with proportional-integrating characteristic. The output signals from the respec
REFERENCES:
patent: 4224660 (1980-09-01), Mohan
patent: 4812669 (1989-03-01), Takeda et al.
patent: 4930064 (1990-05-01), Tanaka et al.
patent: 5132894 (1992-07-01), Rozman et al.
patent: 5296764 (1994-03-01), Asplund et al.
patent: 5323330 (1994-06-01), Asplund et al.
patent: 5397927 (1995-03-01), Suelzle et al.
patent: 5539654 (1996-07-01), .ANG.berg
patent: 5548165 (1996-08-01), Mohan et al.
patent: 5737198 (1998-04-01), Larsen et al.
patent: 5757099 (1998-05-01), Cheng et al.
Gyugyi et al., Active AC Power Filters, Westinghouse Electric Corporation, Research Laboratories, Pittsburgh, PA, IAS '76 Annual, pp. 529-535.
Wong, et al., Feasibiity Study of AC-and DC-Side Active Filters for HVDC Converter Terminals, IEEE Transactions on Power Delivery, vol. 4, No. 4, 1989, pp. 2067-2075.
Asplund et al., Active DC filters for HVDC systems, ABB Review Jun. 7, 1995, pp. 17-21.
Anwendung aktiver Saugkreise in elektrischen Energieversorgungsnetzen, etzArchiv Bd. 9 (1987) H.4, pp. 93-100.
C. Tuttas, Kaiserslautern, Regelung von Blindleistungskompensatoren mit aktiven Filtern, Anwendungsaufsatz, Automatisierungstechnik at 34 Jahrgang, Heft Aug. 1986, pp. 302-310.
berg Anders
Goransson Tor
Nilsson Henrik
Asea Brown Boveri AB
Berhane Adolf Deneke
LandOfFree
Control equipment for an active filter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control equipment for an active filter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control equipment for an active filter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-831321