Power factor regulating method for connection of a capacitor to a line and apparatus embodying the method

• US 4,529,926 A
• Filed: 12/27/1982
• Issued: 07/16/1985
• Est. Priority Date: 09/27/1982
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Shinko Giken
• Original Assignee: Kabushiki Kaisha Shinko Giken
• Inventors: Takada, Shigetoshi
• Primary Examiner(s): BEHA JR, WILLIAM
• Application Number:
  US06/452,903
• Time in Patent Office: 932 Days
• Field of Search: 323/205-211, 307/86
• US Class Current: 523/210
• CPC Class Codes: H02J 3/1864 wherein the stepless control of reactive power is obtained by at least one reactive element connected in series with a semiconductor switch
• CPC Class Codes: Y02E 40/10 Flexible AC transmission systems [FACTS]

Abstract

Power factor regulating method and an apparatus embodying the method in which each of three condensers, which are to be connected to each phase of a three phase distribution line, is preliminarily charged with approximately peak line voltage while a load connected to a distribution line is opened in order to lessen impulse waves that are brought about at the time of connection of the condenser to the appropriate phase of the power line. The present method needs no conventional discharging coil.

Claims

1. Power-factor regulating apparatus comprising:

a delta connected circuit which comprises three series circuits, each of the series circuits connected in parallel with a phase of a distribution line and including;

a parallel circuit composed of a diode and a thyristor connected in parallel, at which the polarities of said diode and said thyristor are reversed, a condenser, and a reactor as wave reformer, connected in series, and

control means for preliminarily charging said condenser to about maximal line voltage while a load is disconnected from said distribution line and thereafter for connecting said condenser to said distribution line by operation of said thyristor at the time the line voltage is at or around its maximum after said load is connected to said distribution line,

wherein said control means includes gate signal generating means for providing a substantially constant signal voltage to a gate of said thyristor beginning at said time when the line voltage is at or around its maximum after said load is connected to said distribution line and terminating at a time when said load is disconnected from said distribution line.

2. Power factor regulating apparatus as recited in claim 1 wherein said control means further includes means for terminating connection of said condenser to said distribution line upon detection of a first line voltage maximum subsequent to disconnection of said load from said distribution line and for maintaining current flow in said condenser until detection of said first line voltage maximum subsequent to disconnection of said load from said distribution line.

3. Power factor regulating apparatus as recited in claim 1 wherein said gate signal generating means includes first detecting means for detecting presence of a maximum value of said line voltage and for generating a first signal indicative thereof and second detecting means for detecting connection of said load to said distribution line and for generating a second signal indicative thereof,

together with means responsive to said first and second signals generated by said first and second detecting means for causing generation of said gate signal when said line voltage reaches said maximum value thereof after connection of said load to said distribution line.

4. Power factor regulating apparatus as recited in claim 3 wherein said means responsive to said first and second signals comprises AND gate means.

5. Power factor regulating apparatus as recited in claim 3 wherein said gate signal generating means further includes third detecting means for detecting removal of said load from said distribution line and for producing a third signal indicative thereof,

together with means responsive to said third signal for terminating said gate signal upon detection of removal of said load from said distribution line.

6. Power factor regulating apparatus as recited in claim 5 wherein said means responsive to said first and second signals and said means responsive to said third signal together comprise set-reset means in said gate signal generating means and connected to be set by said means responsive to said first and second signals and connected to be reset by said third means for producing said gate signal.

7. A power-factor regulating apparatus comprising:

a delta connected circuit which includes three series circuits, each of said series circuits including a condenser connected in series with a circuit composed of a diode and thyristor connected in parallel, at which the polarities of said diode and said thyristor are reversed, connected in series and

three series reactors which are respectively connected between a respective phase of said delta connected circuit and the distribution line,

control means for preliminarily charging said condenser to about maximal line voltage while a load is disconnected from said distribution line and thereafter for connecting said condenser to said distribution line by operation of said thyristor at the time the line voltage is at or around its maximum after said load is connected to said distribution line,

wherein said control means includes gate signal generating means for providing a substantially constant signal voltage to a gate of said thyristor beginning at said time when the line voltage is at or around its maximum after said load is connected to said distribution line and terminating at a time when said load is disconnected from said distribution line,

said control means further including means for terminating connection of said condenser to said distribution line upon detection of a first line voltage maximum subsequent to disconnection of said load from said distribution line and for maintaining current flow in said condenser until detection of said first line voltage maximum subsequent to disconnection of said load from said distribution line.

8. Power-factor regulating method comprising the steps of:

charging a condenser to approximately peak line voltage of a power line during a time when a load is not connected to the power line,

detecting connection and disconnection of the load to and from the power line,

generating signals indicative of connection and disconnection of the load to and from the power line,

detecting peaks in the power line voltage,

generating signals indicative of occurrence of said voltage peaks on said power line,

after detecting connection of the load to the power line, providing a constant gate voltage to activate a thyristor for connecting the condenser to the power line in response to a signal indicative of occurrence of the first subsequent voltage peak on said power line,

terminating said constant gate voltage at an arbitrary time as a function of disconnection of the load from the power line,

after detecting disconnection of the load from the power line, charging the condenser until the first subsequent peak voltage is detected on the power line, and

thereafter providing charge onto said condenser and maintaining the condenser fully charged at approximately said peak line voltage until detection of a next connection of said load to said power line.