High voltage direct current transmission system and control method thereof

Patent metadata

Field	Value
Publication number	US-9614455-B2
Application number	US-201514696076-A
Country	US
Kind code	B2
Filing date	Apr 24, 2015
Priority date	May 13, 2014
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

A high voltage direct current (HVDC) transmission system is provided. The high voltage direct current (HVDC) transmission system includes: a rectifier converting alternating current (AC) power into DC power; an inverter converting the DC power into the AC power; a DC transmission line transmitting, to the inverter, the DC power obtained through conversion by the rectifier; a first active power measurement unit measuring first active power input to the rectifier; a second active power measurement unit measuring second active power output from the inverter; and a first control unit detecting an abnormal voltage state on the DC transmission line based on the first and second active power measured.

First claim

What is claimed is:

1. A high voltage direct current (HVDC) transmission system comprising:
a rectifier configured to convert alternating current (AC) power into direct current (DC) power;
an inverter configured to convert the DC power into the AC power;
a DC transmission line configured to transmit, to the inverter, the DC power obtained through conversion by the rectifier;
a first active power measurement unit configured to measure first active power input to the rectifier;
a second active power measurement unit configured to measure second active power output from the inverter; and
a first control unit configured to:
determine a ratio of the second active power to the first active power; and
detect an abnormal voltage state on the DC transmission line when the determined ratio is out of a threshold ratio range.

2. The high voltage direct current (HVDC) transmission system according to claim 1 , wherein the first control unit is further configured to generate a trip signal stopping the operation of the HVDC transmission system when the abnormal voltage on the DC transmission line is detected.

3. The high voltage direct current (HVDC) transmission system according to claim 1 , wherein:
the first active power measurement unit is further configured to measure an AC and an AC voltage input to the rectifier to measure the first active power, and
the second active power measurement unit is further configured to measure the AC and the AC voltage output from the inverter to measure the second active power.

4. The high voltage direct current (HVDC) transmission system according to claim 1 , further comprising a second control unit configured to receive the second active power measured by the second active power measurement unit.

5. The high voltage direct current (HVDC) transmission system according to claim 4 , wherein the first control unit is further configured to:
receive information on the second active power from the second control unit, and
detect the abnormal voltage state on the DC transmission line based on the first active power and the received information on the second active power.

6. The high voltage direct current (HVDC) transmission system according to claim 1 , further comprising:
a first AC filter configured to remove a harmonic current generated in the power conversion process of the rectifier, and
a second AC filter configured to remove a harmonic current generated in the power conversion process of the inverter.

7. The high voltage direct current (HVDC) transmission system according to claim 1 , wherein the rectifier and the inverter each comprise a thyristor valve or an insulated gate bipolar transistor (IGBT) valve.

8. The high voltage direct current (HVDC) transmission system according to claim 1 , further comprising:
a first capacitor connected to the rectifier in parallel and configured to smooth a DC output from the rectifier; and
a second capacitor connected to the inverter in parallel and configured to smooth a DC input to the inverter.

Assignees

• Lsis Co Ltd

Inventors

• Son Gum Tae
• Park Ho Hwan

Classifications

• H02M5/45

  using semiconductor devices only · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title

• H02M7/7575

  for high voltage direct transmission link · CPC title

• H02M5/4505

  having a rectifier with controlled elements · CPC title

• H02J3/36 Primary

  Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links · CPC title