×

Method and control apparatus for static VAR generator and compensator

  • US 3,999,117 A
  • Filed: 12/23/1974
  • Issued: 12/21/1976
  • Est. Priority Date: 12/23/1974
  • Status: Expired due to Term
First Claim
Patent Images

1. Apparatus for providing reactive power to an alternating current electrical system which includes three electrical conductors, where there is a first alternating voltage of predetermined frequency present between a first and a second of the conductors, a second alternating voltage of said frequency present between the second and a third of said conductors, and a third alternating voltage of said frequency present between the third and the first of said conductors, first, second and third terminal voltages each of which is present respectively between said first, second and third conductors and a common electrical reference point, said electrical system also including a primary source of alternating electrical power connected to the three conductors, said electrical system also including an electrical load connected to the three conductors, the first, second and third terminal voltages having first, second and third peak magnitudes respectively and a given phase relationship relative to each other for a given period of time, comprising:

  • b. a reactive power generator having a first output terminal thereof electrically connected to a place on said first conductor between said load and said primary source and having a second output terminal thereof electrically connected to a place on said second conductor between said load and said primary source, a first alternating load current of said frequency flowing in said first conductor between said place thereon and said load, a second alternating load current of said frequency flowing in said second conductor between said place thereon and said load, said reactive power generator providing a compensating current of said frequency at said first output terminal during a switch controlled portion of a given half cycle of said first alternating voltage, said compensating current being vectorially added to said first alternating load current, a first alternating primary source current of said frequency which flows in said first conductor between said primary source and said place where said first output terminal is connected to said first conductor thus being in predetermined fixed phase relationship with said first terminal voltage for a half cycle, said switch controlled portion being related to a calculated switch delay; and

    b. calculator and sensor means for sensing values of said load currents and said voltages and calculating said switch delay as a function thereof, said calculator and sensor means being connected to said reactive power generator for switching said reactive power generator to thus provide said portion of said compensating current according to the following relationship;

    switch delay being related to the integration of said second load current over the interval of that positive half cycle of said second alternating voltage preceding the switching of said reactive power generator, and the integration of said first load current over the interval of that positive half cycle of said third alternating voltage preceding the switching of said reactive power generator, said switch delay being measured from a point in time when the next following positive peak of said first alternating voltage occurs, all integrations being made with respect to said frequency times time.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×