Reactive power compensation control system

Claim 2

In combination: a source of alternating current; a dynamic reactive load; at least one pair of phase lines connected between said source and said load; a plurality of capacitors for connection to said phase lines; a plurality of switches for connecting said capacitors to said phase lines, one switch being provided for each capacitor and each switch comprising one pair of inverse parallel controlled rectifiers; a plurality of firing circuits for operating said switches, one firing circuit being provided for each switch and each firing circuit comprising a charge section for controlling one rectifier and a discharge section for controlling the other rectifier; and a control circuit coupled to said phase lines between said source and said capacitors and responsive to changes in reactive power conditions in said phase lines resulting from said dynamic reactive load and from the affect of said capacitors for operating said firing circuits, said control circuit comprising an ON section for effecting sequential operation of said charge sections and sequential initial charging of said capacitors to place them in readiness for use, said control Circuit further comprising a RUN section operable in response to said changes in reactive power conditions for effecting synchronous discharge and charge of said capacitors subsequent to their initial charging, said control circuit further comprising means responsive to the magnitude of said changes in reactive power conditions to control the number of capacitors connected for discharge to said phase lines.

Claim 3

A combination according to claim 1 wherein each of said firing circuits includes means responsive to the magnitude and polarity of the voltage across its associated switch during operation of either said ON or said RUN sections to prevent operation of said switch regardless of said change in reactive power conditions while the voltage differential across said switch is beyond a predetermined range, and wherein each of said firing circuits further includes means to prevent operation of its associated switch during operation of said ON section unless the voltage across said switch is at a predetermined phase angle with respect to the applied voltage in the cycle.

Claim 4

A combination according to claim 2 including optical coupling means connected in circuit between said control circuit and said firing circuits for transmitting signal information from said control circuit to said firing circuits while maintaining a predetermined level of voltage isolation therebetween.

Claim 5

A combination according to claim 1 wherein three phase lines are connected between said source and said load and wherein a plurality of capacitors are connected between each pair of phase lines.

Claim 6

A combination according to claim 2 wherein three phase lines are connected between said source and said load and wherein a plurality of capacitors are connected between each pair of phase lines.

Claim 7

In combination: an electric system comprising an alternating current source of power, a load, and three phase lines connected between said source and said load, said system tending to exhibit changes in reactive power conditions therein when handling a dynamic reactive load; and a reactive power compensation control system for said electric power system comprising: a plurality of capacitor banks, each bank comprising at least one capacitor, for connection to each pair of phase lines between said source and said load; a plurality of switches, one for each capacitor and each including a pair of controlled charging and discharging rectifiers connected in inverse parallel relationship with each other and in series with said capacitor across said pair of phase lines, each switch being operable to connect its associated capacitor to its associated pair of phase lines to effect charging and discharging of said capacitor; and control means coupled to said power system between said source and said capacitor banks to operate said switches and comprising: a control circuit responsive to reactive power conditions in said power system resulting from said dynamic reactive load and from the affect of said capacitor, and an ON section and a RUN section; and a plurality of firing circuits operated by said control circuit for operating of said switches, one firing circuit being provided for each switch, and each firing circuit comprising a charge section and a discharge section; said control circuit being operable to cause said ON section to effect sequential operation of said charge sections and said charging rectifiers and to effect sequential charging of said capacitors, and said control circuit being responsive to said reactive power conditions to cause said RUN section to operate subsequent to sequential charging of said capacitors to operate said firing circuits to effect synchronous discharge and charge of said capacitor banks.

Claim 8

In combination: an electric system comprising an alternating current source of power, a load, and three phase lines connected between said source and said load, said system tending to exhibit changes in reactive power conditions therein when handling a dynamic reactive load; and a reactive power compensation control system for said electric power system comprising: a plurality of capacitor banks, each bank comprising at least one capacitor, for connection to each pair of phase lines between said source and said load; a plurality of switches, one for each capacitor and each including a pair of controlled charging and discharging rectifiers connected in inverse parallel relationship with each other and in series with said capacitor across said pair of phase lines, each switch being operable to connect its associated capacitor to its associated pair of phase lines to effect charging and discharging of said capacitor; and control means coupled to said power system between said source and said capacitor banks to operate said switches and comprising: a control circuit responsive to reactive power conditions in said power system resulting from said dynamic reactive load and from the affect of said capacitor, and an ON section and a RUN section; and a plurality of firing circuits operated by said control circuit for operating of said switches, one firing circuit being provided for each switch, and each firing circuit comprising a charge section and a discharge section; said control circuit being operable to cause said ON section to effect sequential operation of said charge sections and said charging rectifiers and to effect sequential charging of said capacitors, and said control circuit being responsive to said reactive power conditions to cause said RUN section to operate subsequent to sequential charging of said capacitors to operate said firing circuits to effect synchronous discharge and charge of said capacitor banks.

Claim 9

A combination according to claim 6 wherein each of said firing circuits includes means responsive to the magnitude and polarity of the voltage across its associated switch during operation of either said ON or said RUN sections to prevent operation of said switch regarDless of said reactive power conditions while the voltage differential across said switch is beyond a predetermined range, and wherein each of said firing circuits further includes means to prevent operation of its associated switch during operation of said ON section unless the voltage across said switch is at a predetermined phase angle with respect to the applied voltage in the cycle.

Claim 10

A combination according to claim 7 including optical coupling means connected in circuit between said control circuit and said firing circuits for transmitting signal information from said control circuit to said firing circuits while maintaining a predetermined level of voltage isolation therebetween.

Claim 11

A combination according to claim 8 wherein said capacitor bank comprises a plurality of capacitors and wherein the capacitors in one bank operate simultaneously with each other.