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Title: Reactive power compensator

Abstract

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the linemore » begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.« less

Inventors:
 [1];  [2];  [3];  [4];  [5]
  1. Renton, WA
  2. Woodinville, WA
  3. Kirkland, WA
  4. Everett, WA
  5. Seattle, WA
Issue Date:
Research Org.:
Univ. of Washington, Seattle, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
868411
Patent Number(s):
5134356
Application Number:
07/665,774
Assignee:
Board of Regents of University of Washington (Seattle, WA)
Patent Classifications (CPCs):
Y - NEW / CROSS SECTIONAL TECHNOLOGIES Y02 - TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE Y02E - REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
H - ELECTRICITY H02 - GENERATION H02J - CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER
DOE Contract Number:  
AI79-87BP65584
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
reactive; power; compensator; method; determining; providing; compensation; inductive; load; 50; monitors; voltage; current; flowing; distribution; lines; 52a; 52b; 52c; supplying; three-phase; loads; signals; indicative; waveform; line; crosses; zero; determines; capacitance; connected; maintain; desired; var; level; factor; alternatively; operator; manually; select; specific; connection; selected; based; time; schedule; produces; control; coupled; optical; fibers; 102; 106; switch; driver; 110; capacitors; 112; connections; develops; triggering; supplied; plurality; series-connected; solid; switches; 350; charge; direction; respect; ground; capacitor; cycle; flows; begins; negative; positive; peak; value; applied; gate; conducting; potential; reaches; minimizing; difference; begin; conduct; harmonic; distortion; carried; filtered; affect; determination; required; voltage waveform; signals indicative; power compensator; line voltage; inductive load; potential difference; reactive power; control signal; optical fibers; optical fiber; current flow; control signals; current flowing; current flows; peak value; selected based; negative peak; distribution lines; connected solid; crosses zero; charge current; power factor; selected base; inductive loads; phase power; power compensation; distribution line; /323/

Citation Formats

El-Sharkawi, Mohamed A, Venkata, Subrahmanyam S, Chen, Mingliang, Andexler, George, and Huang, Tony. Reactive power compensator. United States: N. p., 1992. Web.
El-Sharkawi, Mohamed A, Venkata, Subrahmanyam S, Chen, Mingliang, Andexler, George, & Huang, Tony. Reactive power compensator. United States.
El-Sharkawi, Mohamed A, Venkata, Subrahmanyam S, Chen, Mingliang, Andexler, George, and Huang, Tony. Wed . "Reactive power compensator". United States. https://www.osti.gov/servlets/purl/868411.
@article{osti_868411,
title = {Reactive power compensator},
author = {El-Sharkawi, Mohamed A and Venkata, Subrahmanyam S and Chen, Mingliang and Andexler, George and Huang, Tony},
abstractNote = {A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1992},
month = {1}
}

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