Unified power flow controller for double-circuit line

Patent metadata

Field	Value
Publication number	US-10033186-B2
Application number	US-201515311540-A
Country	US
Kind code	B2
Filing date	Jan 12, 2015
Priority date	May 19, 2014
Publication date	Jul 24, 2018
Grant date	Jul 24, 2018

Abstract

A unified power flow controller for a double-circuit transmission line comprises at least one parallel-connection transformer, three current converters, at least two series-connection transformers, a parallel-connection side switching circuit, a series-connection side switching circuit and a direct current common bus. The series-connection transformers connected with at least one group of by-pass switches in parallel. The three current converters connected to each loop line in series after being connected with at least one series-connection transformer through the series-connection side switching circuit. The three current converters connected to an alternating current system after connected with at least one parallel-connection transformer through a parallel-connection side switching circuit starting circuit. The three current converters are connected to the direct current common bus through a transfer switch.

First claim

The invention claimed is:

1. A unified power flow controller (UPFC) suitable for a double-circuit transmission line, comprising:
the UPFC applied to the double-circuit transmission line comprises at least one parallel-connection transformer, three current converters, at least two series-connection transformers, a parallel-connection side switching circuit, a series-connection side switching circuit and a direct current common bus; at least one side of the series-connection transformers is connected with at least one group of by-pass switches in parallel; alternating current sides of the three current converters are connected to each loop line in series after being connected with at least one series-connection transformer through the series-connection side switching circuit; the alternating current sides of the three current converters are connected to an alternating current system after connected with the at least one parallel-connection transformer through a parallel-connection side switching circuit; and direct current sides of the three current converters are connected to the direct current common bus through a transfer switch.

2. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein the parallel-connection side switching circuit consists of at least one change-over switch, and is configured to connect or disconnect the three converters to or from a parallel-side of the alternating current system in different combination forms; and the series-connection side switching circuit consists of at least one change-over switch, and is configured to connect or disconnect the three converters to or from the series-connection transformers in different combination forms.

3. The UPFC suitable for the double-circuit transmission line according to claim 2 , wherein the change-over switches are isolated switches, or circuit breakers, or switches consisting of power electronic devices.

4. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein the UPFC also comprises at least one parallel-connection side starting circuit, correspondingly, the at least three converters are connected to the at least one parallel-connection side starting circuit by the parallel-connection side switching circuit and are then connected to at least one parallel-connection transformer.

5. The UPFC suitable for the double-circuit transmission line according to claim 3 , wherein the parallel-connection side starting circuit comprises a pair of resistor and switch connected in parallel, the switch is an isolated switch, circuit breaker, or switch consisting of a power electronic device.

6. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein the by-pass switches are by-pass circuit breakers or fast by-pass switches.

7. The UPFC suitable for the double-circuit transmission line according to claim 6 , wherein the at least one group of by-pass circuit breakers is connected to two ends at a line side winding of the series-connection transformer line in parallel and is configured to control the series-connection transformer to connect to or disconnect from the line.

8. The UPFC suitable for the double-circuit transmission line according to claim 6 , wherein the at least one group of fast by-pass switches is connected between phases of a valve side of the series-connection transformer in parallel and is configured to fast bypass and isolate the converters from the line.

9. The UPFC suitable for the double-circuit transmission line according to claim 6 , wherein the fast by-pass switches are circuit breakers, two-way antiparallel thyristors or other power electronic devices.

10. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein the UPFC realizes various operation modes, including but limited to: a double-circuit line UPFC operation mode, a mono-circuit line UPFC operation mode, a static synchronous compensator UPFC operation mode, a static synchronous series-connection compensation UPFC operation mode and an inter-line UPFC operation mode by the switching operation of the parallel-connection side switching circuit and the series-connection side switching circuit.

11. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein the change-over switches are isolated switches, or circuit breakers, or switches consisting of power electronic devices.

12. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein the alternating current system to which the parallel-connection transformer is connected is a common bus of the double-circuit power transmission line, or other alternating current buses.

13. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein the converters are voltage source type converters, including but not limited to a two-level structure, a transformer multi-structure or modular multi-level structure.

14. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein the series-connection transformer is a mono-phase or tri-phase transformer, and the line side winding of the series-connection transformer is serially connected to the line phase by phase.

15. The UPFC suitable for the double-circuit transmission line according to claim 1 , wherein when the UPFC controls an N-circuit line, the number of the converters is at least N+1, the number of the series-connection transformers is at least N and N is a natural number larger than 2.

Assignees

• Nr Electric Co Ltd
• Nr Electric Eng Co Ltd

Inventors

• Tian Jie
• Li Haiying
• Wang Xinbao
• Dong Yunlong
• Shen Quanrong
• Pan Lei
• Liu Chao
• Chang Baoli

Classifications

• H02J3/16

  by adjustment of reactive power · CPC title

• H02J3/14 Primary

  by switching loads on to, or off from, the networks, e.g. progressively balanced loading · CPC title

• H02J3/46

  Controlling the sharing of generated power between the generators, sources or networks · CPC title

• H02J3/1814 Primary

  having reactive elements actively controlled by bridge converters, e.g. unified power flow controllers [UPFC] or controlled series voltage compensators · CPC title

• Y02B70/3225

  Demand response systems, e.g. load shedding, peak shaving · CPC title