Series compensator and control method

Patent metadata

Field	Value
Publication number	US-11264794-B2
Application number	US-201816649113-A
Country	US
Kind code	B2
Filing date	Sep 11, 2018
Priority date	Dec 20, 2017
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

The present invention provides a series compensator and a control method. The series compensator includes a series transformer, a series transformer bypass device, a voltage source converter, a high-speed converter bypass device, a high-speed switch, and a reactor. The reactor and the high-speed switch are connected in parallel to form a current limiting module; one winding of the series transformer has two ends connected in series to a line, and the other winding thereof is sequentially connected to the current limiting module and the high-speed converter bypass device; the voltage source converter and the high-speed converter bypass device are connected in parallel; and at least one winding of the series transformer are connected in parallel to at least one series transformer bypass device. The series compensator of the present invention indirectly provides the current limiting module, so as to effectively limit the short-circuit current of a system, reduce the fault current to which the compensator is subjected, and improve the reliability of an alternating current system and the series compensator. Moreover, the current limiting module has a low voltage level, and the high-speed switch has a small breaking current, thereby providing good industrial applicability.

First claim

The invention claimed is:

1. A series compensator, comprising:
a series transformer, at least one series transformer bypass device, a voltage source converter, at least one high-speed converter bypass device, at least one high-speed switch, and at least one reactor, wherein
the reactor and the high-speed switch are connected in parallel to form a current limiting module;
one winding of the series transformer has two ends connected in series to a line, and the other winding thereof is sequentially connected to the current limiting module and the high-speed converter bypass device; the voltage source converter and the high-speed converter bypass device are connected in parallel; and at least one winding of the series transformer are connected in parallel to the at least one series transformer bypass device; and
the current limiting module further comprises at least one capacitor, the capacitor is connected in parallel to the reactor to form an impedance unit; and the impedance unit is connected in parallel to the high-speed switch to form a current limiting module;
wherein at least one winding of the series transformer are connected in parallel to at least one overvoltage protection device; and two ends of the high-speed converter bypass device are connected in parallel to at least one overvoltage protection device.

2. The series compensator according to claim 1 , wherein
the series transformer is a single-phase transformer; two ends of a first winding of the series transformer are connected in series to a line; a first end of a second winding of the series transformer is connected to a first end of the current limiting module; a second end of the current limiting module is connected to a first end of the high-speed converter bypass device; a second end of the high-speed converter bypass device is connected to a second end of the second winding of the series transformer; and a first output end of the voltage source converter is connected to the first end of the high-speed converter bypass device, and a second output end of the voltage source converter is connected to the second end of the second winding of the series transformer.

3. The series compensator according to claim 1 , wherein
the series transformer is a three-phase transformer; two ends of three phases of a first winding of the series transformer are connected in series to a three-phase alternating current line, respectively; a second winding of the series transformer is in a star connection; three phases of an output end of the second winding of the series transformer are connected to three phases of the first end of the current limiting module, respectively; three phases of the second end of the current limiting module are connected to three phases of the first end of the high-speed converter bypass device, respectively; three phases of the second end of the high-speed converter bypass device are connected to a neutral line of the second winding of the series transformer; and a three-phase alternating current output side of the voltage source converter is connected to three phases of the second end of the current limiting module.

4. The series compensator according to claim 1 , wherein
the series transformer is a three-phase transformer; two ends of three phases of a first winding of the series transformer are connected in series to a three-phase alternating current line, respectively; a second winding of the series transformer is in a triangle connection; three-phase windings of the second winding of the series transformer are sequentially connected end-to-end to form a triangle structure and form a three-phase output end; a three-phase output end of the second winding of the series transformer is connected to three phases of the first end of the current limiting module, respectively; three phases of the second end of the current limiting module are connected to three phases of an alternating current output end of the voltage source converter, respectively; three-phase devices of the high-speed converter bypass device are sequentially connected end-to-end to form a triangle structure and form a three-phase output end; and the three-phase output end of the high-speed converter bypass device is connected to three phases of the alternating current output end of the voltage source converter, respectively.

5. The series compensator according to claim 1 , wherein a first end of the first winding of the series transformer is connected to a first end of the series transformer bypass device by means of a breaker, and a second end of the first winding of the series transformer is connected to a second end of the series transformer bypass device by means of an isolating switch; or two ends of a winding of the series transformer connected to the line are connected to two ends of the series transformer bypass device by means of a breaker, respectively.

6. The series compensator according to claim 1 , wherein the overvoltage protection device comprises an arrester and a gap.

7. The series compensator according to claim 1 , wherein
the series transformer bypass device is a mechanical bypass switch, or is a bypass switch composed of power electronic devices; the high-speed converter bypass device is a high-speed mechanical bypass switch, or a high-speed bypass switch composed of power electronic devices; and the high-speed switch is a mechanical switch, or a switch composed of power electronic devices.

8. The series compensator according to claim 3 , wherein
the series transformer comprises a third winding; a winding of one phase of the third winding is connected in series to one reactor, and then is sequentially connected to windings of the other two phases end-to-end to form a triangle structure and form a three-phase output end.

9. The series compensator according to claim 3 , wherein
the neutral line of the second winding of the series transformer is directly grounded, or is electrically grounded by means of a resistor, or is grounded by means of a reactor.

10. A control method for the series compensator according to claim 1 , wherein
the series compensator comprises a series transformer, at least one series transformer bypass device, a voltage source converter, at least one high-speed converter bypass device, at least one high-speed switch, and at least one reactor;
the reactor and the high-speed switch are connected in parallel to form a current limiting module;
one winding of the series transformer has two ends connected in series to a line, and the other winding thereof is sequentially connected to the current limiting module and the high-speed converter bypass device; the voltage source converter and the high-speed converter bypass device are connected in parallel; at least one winding of the series transformer are connected in parallel to the at least one series transformer bypass device;
the control method for the series compensator comprises: when an alternating current system is operating normally, keeping the high-speed switch connected in parallel to the reactor in a closed state, the series transformer bypass device in an OFF state, the high-speed converter bypass device in an OFF state, and the voltage source converter in a deblocked state, and switching on the series compensator for operation in the alternating current system; and
after determining that a serious fault occurs at a near end of a line, first blocking the voltage source converter and switching on the high-speed converter bypass device, and then opening the high-speed switch connected in parallel to the reactor to limit a line fault current; and after determining that the line fault is cleared, switching on the series transformer bypass device, and closing the high-speed switch connecte

Assignees

• Nr Electric Co Ltd
• Nr Engineering Co Ltd

Inventors

• Pan Lei
• Tian Jie
• Cao Dongming
• Dong Yunlong
• Zhou Qiwen
• Huang Ruhai
• Ding Fengfeng

Classifications

• H02J3/001

  Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies · CPC title

• H02J3/00 Primary

  Circuit arrangements for AC mains or AC distribution networks · CPC title

• H02J13/00

  Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network · CPC title

• Y02E60/00

  Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation · CPC title

• H01H71/24

  Electromagnetic mechanisms · CPC title