US4811236A — Transmission line voltage detector for static VAR…

Claim 1

Independent Claim 225 words

A controlled static VAR generator including static power switches controlled for coupling a reactive power source onto AC transmission lines for power factor compensation thereof and detection means responsive to the AC transmission line voltage for providing a control signal representative of the amplitude of said line voltage, said control signal being applied to said static power switches; said detection means comprising: means responsive to the AC transmission line voltage for deriving a time related signal V(t) representative thereof and of fundamental frequency ω=2πf; means synchronized with said AC transmission line voltage for providing a first signal representative of cos (ωt) and a second signal representative of sin (ωt); first multiplier means for providing with said time related signal V(t) and said cos (ωt) representative signal a signal representative of a first product V(t)×cos (ωt); second multiplier means for providing with said time related signal V(t) and said sin (ωt) representative signal a signal representative of a second product V(t)×sin (ωt); first means for integrating through the fundamental period T said first product representative signal to derive the Fourier coefficient ##EQU4## second means for integrating through the fundamental period T said second product representative signal to derive the Fourier coefficient ##EQU5## means responsive to said first and second integrating means for deriving said control signal as a voltage amplitude representative signal V by calculating ##EQU6##

Claim 2

Dependent Claim 225 words

A controlled static VAR generator including static power switches controlled for coupling a reactive power source onto AC transmission lines for power factor compensation thereof and detection means responsive to the AC transmission line voltage for providing a control signal representative of the amplitude of said line voltage, said control signal being applied to said static power switches; said detection means comprising: means responsive to the AC transmission line voltage for deriving a time related signal V(t) representative thereof and of fundamental frequency ω=2πf; means synchronized with said AC transmission line voltage for providing a first signal representative of cos (ωt) and a second signal representative of sin (ωt); first multiplier means for providing with said time related signal V(t) and said cos (ωt) representative signal a signal representative of a first product V(t)×cos (ωt); second multiplier means for providing with said time related signal V(t) and said sin (ωt) representative signal a signal representative of a second product V(t)×sin (ωt); first means for integrating through the fundamental period T said first product representative signal to derive the Fourier coefficient ##EQU4## second means for integrating through the fundamental period T said second product representative signal to derive the Fourier coefficient ##EQU5## means responsive to said first and second integrating means for deriving said control signal as a voltage amplitude representative signal V by calculating ##EQU6##

Claim 3

Dependent Claim 83 words

The generator of claim 1 with said time related signal V(t) deriving means and said synchronized means each including means for sampling the inputted signal for deriving an output sample, said first and second multiplier means being operative on said output samples to generate samples of said first and second products; said first and second integrating means being operative on N samples of said first and second multiplier means respectively, within the period T to provide said Fourier coefficients as an average thereof.

Claim 4

Dependent Claim 37 words

The generator of claim 2 with upon each new sample into said first and second integrating means, respectively, said average is effected on N samples within the window T, on a first IN and last OUT basis.

Claim 5

Dependent Claim 18 words

The generator of claim 2 with said first and second integrating means, each including Fast Fourier Transformer means.

Claim 6

Dependent Claim 178 words

The generator according to claim 1 with said AC transmission lines being a three-phase AC transmission line system; said detection means being responsive to said AC line system for deriving three respective transmission line phase voltage representative signals, V 1 , V 2 , V 3 as said V(t) signal; first, second and third combinations of said V(t) signal deriving means, of said synchronized means, of said first and second multiplier means, and of said first and second integrating means responsive to said phase voltage representative signals, respectively for computing Fourier coefficients ##EQU7## and ##EQU8## where T=2π/ω the period of the fundamental in said transmission lines; fourth, fifth and sixth means for said three phases, respectively, responsive to a corresponding one of said first, second and third combinations for calculating amplitude voltages V 1 , V 2 , V 3 for the respective phases in accordance with the formula ##EQU9## and said deriving means combining V 1 +V 2 +V 3 to derive said control signal representative of an error in the amplitude voltage on said transmission lines.

Claim 7

Dependent Claim 16 words

The system of claim 5 with said first, second and third means being sliding window integrators.

Claim 8

Dependent Claim 47 words

The system of claim 6 with each of said first, second and third means involving a pair of sliding window integrators affected to said A and B Fourier coefficient, respectively; means being provided for resetting said sliding window integrator periodically after a multiple number of T periods.

Claim 9

Dependent Claim 26 words

The system of claim 7 with said resetting means being operative cyclically and permutatively on six said sliding window integrators, thereby to eliminate any accumulated error.

Claim 10

Dependent Claim 17 words

The system of claim 5 with said control signal being used to balance out said transmission lines.

Claim 11

Dependent Claim 19 words

The system of claim 5 with said control signal being used to eliminate a disturbance in said transmission lines.

Claim 12

Dependent Claim 23 words

The system of claim 6 with said sliding window integrators being sampled at frequency which is a multiple of the transmission line frequency.

Claim 13

Dependent Claim 188 words

An amplitude detector system for deriving a signal representative of themagnitude of one electrical quantity E(t) as a function of time, as a characteristic of an AC transmission line comprising: means responsive to the AC transmission line for deriving a time related signal E(t) representative thereof and of fundamental frequency ω=2πf; means synchronized with said AC transmission line quantity for providing a first signal representative of cos (ωt) and a second signal representative of sin (ωt); first multiplier means for providing with said time related signal E(t) and said cos (ωt) representative signal a signal representative of a first product E(t)×cos (ωt); second multiplier means for providing with said time related signal E(t) and said sin (ωt) representative signal a signal representative of a second product E(t)×sin (ωt); first means for integrating through the fundamental period T said first product representative signal to derive the Fourier coefficient ##EQU10## second means for integrating through the fundamental period T said second product representative signal to derive the Fourier coefficient ##EQU11## and means responsive to said first and second integrating means for deriving said magnitude representative signal E(t) by calculating ##EQU12##

Claim 14

Dependent Claim 188 words

An amplitude detector system for deriving a signal representative of themagnitude of one electrical quantity E(t) as a function of time, as a characteristic of an AC transmission line comprising: means responsive to the AC transmission line for deriving a time related signal E(t) representative thereof and of fundamental frequency ω=2πf; means synchronized with said AC transmission line quantity for providing a first signal representative of cos (ωt) and a second signal representative of sin (ωt); first multiplier means for providing with said time related signal E(t) and said cos (ωt) representative signal a signal representative of a first product E(t)×cos (ωt); second multiplier means for providing with said time related signal E(t) and said sin (ωt) representative signal a signal representative of a second product E(t)×sin (ωt); first means for integrating through the fundamental period T said first product representative signal to derive the Fourier coefficient ##EQU10## second means for integrating through the fundamental period T said second product representative signal to derive the Fourier coefficient ##EQU11## and means responsive to said first and second integrating means for deriving said magnitude representative signal E(t) by calculating ##EQU12##

Claim 15

Dependent Claim 83 words

The detector of claim 12 with said time related signal E(t) deriving means and said synchronized means each including means for sampling the inputted signal for deriving an output sample, said first and second multiplier means being operative on said output samples to generate samples of said first and second products; said first and second integrating means being operative on N samples of said first and second multiplier means respectively, within the period T to provide said Fourier coefficient as an average thereof.

Claim 16

Dependent Claim 37 words

The detector of claim 13 with upon each new sample into said first and second integrating means, respectively, said average is effected on N samples within the window T, on a first IN and last OUT basis.

Claim 17

Dependent Claim 18 words

The detector of claim 13 with said first and second integrating means, each including Fast Fourier Transformer means.

Claim 18

Dependent Claim 16 words

The detector of claim 12 with said electrical quantity being the voltage of the transmission line.

Claim 19

Dependent Claim 16 words

The detector of claim 12 with said electrical quantity being the current of the transmission line.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-03-06	1992-09-05	1993-03-07	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-03-06	1996-09-05	1997-03-07	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-03-06	2000-09-05	2001-03-07	$7700.00	Window Closed / Lapsed

Transmission line voltage detector for static VAR generator

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