Control apparatus and method in static VAR compensator system

Patent metadata

Field	Value
Publication number	US-10056825-B2
Application number	US-201715412004-A
Country	US
Kind code	B2
Filing date	Jan 21, 2017
Priority date	Jan 26, 2016
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

A control apparatus in a static VAR compensator (SVC) system includes a plurality of current supply units for supplying phase currents configuring three-phase current of a power system, a plurality of current sensors for measuring the phase currents, and a controller for determining whether unbalance occurs in the three-phase current based on the phase currents, calculating an error corresponding to the unbalance according to the phase currents if unbalance occurs, and individually controlling at least one of the plurality of current supply units so as to compensate for the error.

First claim

The invention claimed is:

1. A control apparatus in a static VAR compensator (SVC) system, comprising:
a plurality of current supply units configured to supply phase currents configuring three-phase current of a power system;
a plurality of current sensors configured to measure the phase currents; and
a controller configured to determine whether unbalance occurs in the three-phase current based on the phase currents, calculate an error corresponding to the unbalance according to the phase currents if the unbalance occurs, and individually control at least one of the plurality of current supply units so as to compensate for the error,
wherein the controller includes:
a plurality of differentiators, wherein the plurality of differentiators differentiate the phase currents,
a plurality of integrators, wherein the plurality of integrators generate first values by integrating the differentiated phase currents,
a plurality of constant determination units, wherein the plurality of constant determination units generate second values by applying a constant to the first values, and
an adder, wherein the adder adds the second values to determine whether the unbalance occurs in the three-phase current.

2. The control apparatus according to claim 1 , wherein:
each of the plurality of current supply units includes a thyristor which is turned on in order to supply the phase currents; and
the controller individually turns the thyristor on so as to compensate for the unbalance according to the phase currents.

3. The control apparatus according to claim 1 , wherein the controller calculates a root mean square (RMS) value of the three-phase current and determines whether the unbalance occurs in the three-phase current based on the RMS value.

4. The control apparatus according to claim 1 , wherein the controller measures and applies an internal current of the SVC system and calculates a constant for operation characteristics of the SVC system.

5. A control method of a control apparatus in a static VAR compensator (SVC) system, the control method comprising:
supplying phase currents configuring three-phase current of a power system;
measuring the phase currents;
determining whether unbalance occurs in the three-phase current based on the phase currents;
calculating an error corresponding to the unbalance according to the phase currents if the unbalance occurs; and
individually controlling at least one of a plurality of current supply units so as to compensate for the error;
wherein the determining step includes:
differentiating the phase currents;
integrating the differentiated phase currents to generate first values;
applying a constant to the first values to generate second values; and
adding the second values to determine whether the unbalance occurs in the three-phase current.

6. The control method according to claim 5 , wherein:
each of the plurality of current supply units includes a thyristor which is turned on in order to supply the phase currents; and
the control apparatus individually turns the thyristor on so as to compensate for the unbalance according to the phase currents.

7. The control method according to claim 5 , further comprising:
calculating a root mean square (RMS) value of the three-phase current; and
determining whether the unbalance occurs in the three-phase current based on the RMS value.

8. The control method according to claim 7 , further comprising:
measuring and applying an internal current of the SVC system; and
calculating a constant for operation characteristics of the SVC system.

9. A static VAR compensator (SVC) system, comprising:
a device configured to supply phase currents configuring three-phase current of a power system; and
a control apparatus configured to measure the phase currents, determine whether unbalance occurs in the three-phase current based on the phase currents, and individually control at least one of the phase currents so as to compensate for the unbalance according to the phase currents when the unbalance occurs,
wherein the control apparatus is further configured to:
differentiate the phase currents,
generate first values by integrating the differentiated phase currents,
generate second values by applying a constant to the first values, and
add the second values to determine whether the unbalance occurs in the three-phase current.

10. The SVC system according to claim 9 , wherein the control apparatus calculates an error corresponding to the unbalance according to the phase currents and individually controls at least one of the phase currents so as to compensate for the error.

Assignees

• Lsis Co Ltd

Inventors

• Choi Ho Seok

Classifications

• Y02E40/50

  Arrangements for eliminating or reducing asymmetry in polyphase networks · CPC title

• H02J3/26

  Arrangements for eliminating or reducing asymmetry in polyphase networks · CPC title

• H02M1/08

  Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters · CPC title

• H02J3/1864 Primary

  using reactive elements connected in series with semiconductor switches, e.g. static VAR compensators [SVC], thyristor-controlled reactors [TCR] or thyristor-switched capacitors [TSC] · CPC title

• H02M1/4208 Primary

  Arrangements for improving power factor of AC input · CPC title