System and method for detecting partial discharge of gas-insulated switchgear

• US 5,200,737 A
• Filed: 11/29/1991
• Issued: 04/06/1993
• Est. Priority Date: 11/30/1990
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sakakibara, Takaaki, Konishi, Katsumi
• Primary Examiner(s): Weider, Kenneth A.
• Assistant Examiner(s): Solis, Jose M.
• Application Number:
  US07/799,945
• Time in Patent Office: 494 Days
• Field of Search: 361/84, 361/85, 361/86, 361/87, 340/644, 340/646, 340/647, 340/658, 324/424, 324/455, 324/456, 324/514, 324/520, 324/536, 324/547, 324/552, 324/535
• US Class Current: 340/644
• CPC Class Codes: G01R 31/1254 of gas-insulated power appliances or vacuum gaps testing switches G01R31/327; detecting electrical or mechanical defects in encased switchgear H02B13/065
• CPC Class Codes: G01R 31/3275 Fault detection or status indication
• CPC Class Codes: H01H 33/26 Means for detecting the presence of an arc or other discharge

Abstract

A system and method for detecting partial discharge of gas-insulated switchgear wherein a high-frequency component and the fundamental wave component of the voltage applied to the conductor of the gas-insulated switchgear are detected, the zero-cross point of the fundamental wave component is set as the starting point for the voltage, and the presence of partial discharge and the reason for the occurrence of partial discharge are ascertained based on the phase difference between the phase of the detected high-frequency component and the phase of the starting point of the voltage.

Claims

1. A method for detecting partial discharge generated in an interior of a gas-insulated switchgear used in a transformer installation, comprising the following steps:

detecting a high-frequency component of a voltage applied to a conductor of said gas-insulated switchgear;

detecting a fundamental wave component of the voltage applied to the conductor of said gas-insulated switchgear;

determining whether said partial discharge gas has occurred, and a reason for said partial discharge, based upon a relationship between said high-frequency component and said fundamental wave component of the voltage applied to the conductor of said gas-insulated switchgear;

frequency modulating said detected high frequency component and said fundamental wave component;

converting said frequency-modulated high-frequency component and said frequency-modulated fundamental wave component into respective first and second optical signals;

outputting said first and second optical signals into a fiberoptic network;

receiving said first and second optical signals from said fiberoptic network and converting said first and second optical signals into first and second frequency-modulated signals;

converting said first and second frequency-modulated signals into first and second pulse signals;

outputting said second pulse signal to a computing element;

converting said first pulse signal into a digital signal and inputting said digital signal to said computing element in response to said computing element receiving said second pulse signal; and

comparing said digital signal with digital signals representing known patterns of said partial discharge, and determining said partial discharge has occurred and said reason for said occurrence of said partial discharge if said digital signal corresponds with at least one of said digital signals representing said known patterns of said partial discharge.

2. A system for detecting partial discharge generated in an interior of a gas-insulated switchgear used in a transformer installation, comprising:

high-frequency detection means for detecting a high-frequency component of a voltage applied to said gas-insulated switchgear;

fundamental wave detection means for detecting the fundamental wave component of the voltage applied to one gas-insulated switchgear;

voltage starting-point setting means for detecting a zero-crossing point of the fundamental wave component obtained by said fundamental wave detection means, and setting a starting point based upon said zero-crossing point;

detected signal processing means for performing signal processing on a first output signal of said high-frequency detection means and a second output signal of said voltage starting-point setting means, and outputting respective first and second optical signals corresponding to said first and second output signals; and

partial discharge decision means for converting said first and second optical signals from said detected signal processing means into respective first and second pulse signals and ascertaining an occurrence of partial discharge and a reason for the occurrence of partial discharge, based on said first and second pulse signals;

wherein said partial discharge decision means comprises;

converter means for converting said second pulse signal into a digital signal; and

computing means for outputting a timing pulse signal upon receipt of said first pulse signal;

wherein said timing pulse signal is output to said converting means which outputs said digital signal to said computing means upon receiving said timing pulse signal; and

said computing means compares said digital signal with known reference patterns corresponding to patterns of partial discharge and outputs a signal indicating occurrence of partial discharge when said digital signal corresponds to at least one of said known reference patterns.

3. A system as recited in claim 2, wherein said computing means further comprises memory means for storing said digital signal and said known patterns of partial discharge.

4. A system as recited in claim 2, wherein said computing means comprises means for producing said timing pulse signal as a series of consecutive pulse signals over a single cycle of said fundamental wave component.

5. A system for detecting partial discharge generated in an interior of a gas-insulated switchgear used in a transformer installation, comprising:

high-frequency detection means for detecting a high-frequency component of a voltage applied to said gas-insulated switchgear;

fundamental wave detection means for detecting the fundamental wave component of the voltage applied to said gas-insulated switchgear;

voltage starting-point setting means for detecting a zero-crossing point of the fundamental wave component obtained by said fundamental wave detection means, and setting a starting point based upon said zero-crossing point;

detected signal processing means for performing signal processing on a first output signal of said high-frequency detection means and a second output signal of said voltage starting-point setting means, and outputting respective first and second optical signals corresponding to said first and second output signals; and

partial discharge decision means for converting said first and second optical signals from said detected signal processing means into respective first and second pulse signals and ascertaining an occurrence of partial discharge and a reason for the occurrence of partial discharge, based on said first and second pulse signals;

wherein said high-frequency detection means comprises;

a first band-pass filter for extracting said high-frequency component of said voltage and outputting a first signal; and

a first amplifier for amplifying said first signal;

wherein said fundamental wave detection means comprises;

a second band-pass filter for extracting said fundamental wave component and outputting a second signal; and

a second amplifier for amplifying said second signal;

wherein said voltage starting-point setting means comprises;

a comparator for detecting said zero-crossing point of said fundamental wave component using said amplified second signal, and outputting a third signal; and

pulse shaping means for pulse shaping said third signal and outputting a fourth signal; and

wherein said detected signal processing means comprises;

detecting means for detecting said high-frequency component using said amplified first signal and for outputting a fifth signal;

peak hold means for converting said fifth signal into a fixed pulse width signal;

first frequency modulating means for frequency modulating said fixed pulse width signal; and

first optical converter means for converting said frequency-modulated fixed pulse width signal into said first optical signal;

second frequency modulating means for frequency modulating said fourth signal; and

second optical converter means for converting said frequency-modulated fourth signal into said second optical signal.

6. A system for detecting partial discharge generated in an interior of a gas-insulated switchgear used in a transformer installation, comprising:

high-frequency detection means for detecting a high-frequency component of a voltage applied to said gas-insulated switchgear;

fundamental wave detection means for detecting the fundamental wave component of the voltage applied to said gas-insulated switchgear;

voltage starting-point setting means for detecting a zero-crossing point of the fundamental wave component obtained by said fundamental wave detection means, and setting a starting point based upon said zero-crossing point;

detecting signal processing means for performing signal processing on a first output signal of said high-frequency detection means and a second output signal of said voltage starting-point setting means, and outputting respective first and second optical signals corresponding to said first and second output signals; and

partial discharge decision means for converting said first and second optical signals from said detected signal processing means into respective first and second pulse signals and ascertaining an occurrence of partial discharge and a reason for the occurrence of partial discharge, based on said first and second pulse signals;

wherein said partial discharge decision means comprises;

first optical converting means for converting said first optical signal into a first frequency-modulated signal;

first frequency converting means for converting said first frequency-modulated signal into a first voltage signal;

a first amplifier for amplifying said first voltage signal;

integrating means for integrating said amplified first voltage signal and outputting said first pulse signal

second optical converting means for converting said second optical signal into a second frequency-modulated signal;

second frequency modulating means for converting said second frequency-modulated signal into a second voltage signal;

a second amplifier for amplifying said second voltage signal;

waveform shaping means for producing said second pulse signal using said amplified second voltage signal;

converter means for converting said first pulse signal into a digital signal; and

computing means for outputting a pulse timing signal upon reception of said first pulse signal from said waveform shaping means to said converter means, said converter means outputting said digital signal to said computing means, and for determining said occurrence and said reason for said occurrence of partial discharge using said digital signal.

7. A method for detecting partial discharge generated in an interior of a gas-insulated switchgear used in a transformer installation, comprising the following steps:

detecting a first high-frequency component of a voltage applied to a conductor of said gas-insulated switchgear due to noise superimposed on said voltage;

detecting a second high-frequency component of said voltage applied to said conductor of said gas-insulated switchgear due to said partial discharge in said interior of said gas-insulated switchgear;

detecting a fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear; and

determining whether said partial discharge has occurred, and a reason for said partial discharge, based upon a relationship between said first and second high-frequency components and said fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

wherein said determining steps comprises;

detecting a zero-crossing point of said fundamental wave component, said zero crossing point being a starting point of said voltage;

determining a first pattern of said first high-frequency component in terms of a phase relationship with said fundamental wave component using said starting point;

determining a second pattern of said second high-frequency component in terms of said phase relationship with said fundamental wave component using said starting point;

determining a third pattern by cancelling portions of said second pattern which overlap said first pattern;

comparing said third pattern with known patterns of said partial discharge; and

determining said partial discharge has occurred and said reason for said occurrence of said partial discharge if said third pattern corresponds with at least one of said known patterns.

8. A system for detecting partial discharge generated in the interior of a gas-insulated switchgear used in a transformer installation, comprising:

first high-frequency detection means, provided at a bushing of said gas-insulated switchgear, for detecting a first high-frequency component superimposed on the voltage applied to the conductor of said gas-insulated switchgear, caused by external noise entering said gas-insulated switchgear;

second high-frequency detection means, provided at a central location of said gas-insulated switchgear, for detecting a second high-frequency component superimposed on the voltage applied to the conductor of said gas-insulated switchgear, caused by partial discharge in said interior of said gas-insulated switchgear;

fundamental wave detection means for detecting a fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

voltage starting-point setting means for detecting a zero-crossing point of said fundamental wave component obtained by said fundamental wave detection means, and setting a starting point based upon said zero-crossing point;

detected signal processing means for performing signal processing on a first output signal of said first high-frequency detection means, a second output signal of said second high-frequency detection means, and a third output signal of said voltage starting-point setting means, and outputting respective first, second and third optical signals corresponding to said first, second and third output signals; and

partial discharge decision means for converting said first, second and third optical signals from said detected signal processing means into respective first, second and third pulse signals and ascertaining an occurrence of partial discharge and a reason for said occurrence of partial discharge, based on a relationship between said first, second and third pulse signals;

wherein said partial discharge decision means comprises;

first converter means for converting said first pulse signal into a first digital signal;

second converter means for converting said second pulse signal into a second digital signal; and

computing means for outputting a timing pulse signal upon receiving said third pulse signal to said first and second converting means which respectively output said first and second digital signals to said computing means upon receipt of said timing pulse signal, for cancelling portions of said second digital signal which are input to said computing means substantially simultaneously with said first digital signal and storing remaining portions of said second digital signal, for comparing said stored portions of said second digital signal with known reference patterns corresponding to patterns of partial discharge, and for outputting an occurrence of partial discharge signal and a reason for said occurrence of partial discharge when said stored portions of said second digital signal corresponds to at least one of said known reference patterns.

9. A system as recited in claim 8, wherein said computing means further comprises memory means for storing said portions of said second digital signal and said known patterns of partial discharge.

10. A system as recited in claim 8, wherein said computing means comprises means for producing said timing pulse signal as a series of consecutive pulse signals over a single cycle of said fundamental wave component.

11. A system for detecting partial discharge generated in the interior of a gas-insulated switchgear used in a transformer installation, comprising:

first high-frequency detection means, provided at a bushing of said gas-insulated switchgear, for detecting a first high-frequency component superimposed on the voltage applied to the conductor of said gas-insulated switchgear, caused by external noise entering said gas-insulated switchgear;

second high-frequency detection means, provided at a central location of said gas-insulated switchgear, for detecting a second high-frequency component superimposed on the voltage applied to the conductor of said gas-insulated switchgear, caused by partial discharge in said interior of said gas-insulated switchgear;

fundamental wave detection means for detecting a fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

voltage starting-point setting means for detecting a zero-crossing point of said fundamental wave component obtained by said fundamental wave detection means, and setting a starting point based upon said zero-crossing point;

detected signal processing means for performing signal processing on a first output signal of said first high-frequency detection means, a second output signal of said second high-frequency detection means, and a third output signal of said voltage starting-point setting means, and outputting respective first, second and third optical signals corresponding to said first, second and third output signals; and

partial discharge decision means for converting said first, second and third optical signals from said detected signal processing means into respective first, second and third pulse signals and ascertaining an occurrence of partial discharge and a reason for said occurrence of partial discharge, based on a relationship between said first, second and third pulse signal;

wherein said first high-frequency detection means comprises;

first band-pass filter for extracting said first high-frequency component of said voltage and outputting a first signal; and

a first amplifier for amplifying said first signal;

wherein said second high-frequency detection means comprises;

a second band-pass filter for extracting said second high-frequency component of said voltage and outputting a second signal; and

a second amplifier for amplifying said second signal;

wherein said fundamental wave detection means comprises;

a third band-pass filter for extracting said fundamental wave component and outputting a third signal; and

a third amplifier for amplifying said third signal;

wherein said voltage starting-point setting means comprises;

a comparator for detecting said zero-crossing point of said fundamental wave component using said amplified third signal, and outputting a fourth signal; and

pulse shaping means for pulse shaping said fourth signal and outputting a fifth signal; and

wherein said detected signal processing means comprises;

first detecting means for detecting said first high-frequency component using said amplified first signal and for outputting a sixth signal;

first peak hold means for converting said sixth signal into a first fixed pulse width signal;

first frequency modulating means for frequency modulating said first fixed pulse width signal;

first optical converter means for converting said frequency modulated first fixed pulse width signal into said first optical signal;

second detecting means for detecting said second high-frequency component using said amplified first signal and for outputting a seventh signal;

second peak hold means for converting said seventh signal into a second fixed pulse width signal;

second frequency modulating means for frequency modulating said second fixed pulse width signal;

second optical converter means for converting said frequency modulated second fixed pulse width signal into said second optical signal;

third frequency modulating means for frequency modulating said fifth signal; and

third optical converter means for converting said frequency-modulated fifth signal into said third optical signal.

12. A system as recited in claim 11, comprising:

said first bandpass filter having a first bandpass frequency; and

said second bandpass filter having a second bandpass frequency lower than said first bandpass frequency.

13. A system for detecting partial discharge generated in the interior of a gas-insulated switchgear used in a transformer installation, comprising:

first high-frequency detection means, provided at a bushing of said gas-insulated switchgear, for detecting a first high-frequency component superimposed on the voltage applied to the conductor of said gas-insulated switchgear, caused by external noise entering said gas-insulated switchgear;

second high-frequency detection means, provided at a central location of said gas-insulated switchgear, for detecting a second high-frequency component superimposed on the voltage applied to the conductor of said gas-insulated switchgear, caused by partial discharge in said interior of said gas-insulated switchgear;

fundamental wave detection means for detecting a fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

voltage starting-point setting means for detecting a zero-crossing point of said fundamental wave component obtained by said fundamental wave detection means, and setting a starting point based upon said zero-crossing point;

detected signal processing means for performing signal processing on a first output signal of said first high-frequency detection means, a second output signal of said second high-frequency detecting means, and a third output signal of said voltage starting-point setting means, and outputting respective first, second and third optical signals corresponding to said first, second and third output signals; and

partial discharge decision means for converting said first, second and third optical signals from said detected signal processing means into respective first, second and third pulse signals and ascertaining an occurrence of partial discharge and a reason for said occurrence of partial discharge, based on a relationship between said first, second and third pulse signals;

wherein said partial discharge decision means comprises;

first optical converting means for converting said first optical signal into a first frequency-modulated signal;

first frequency converting means for converting said first frequency-modulated signal into a first signal;

a first amplifier for amplifying said first signal;

first integrating means for integrating said amplified first signal and outputting said first pulse signal;

second optical converting means for converting said second optical signal into a second frequency-modulated signal;

second frequency converting means for converting said second frequency-modulated signal into a second signal;

a second amplifier for amplifying said second signal;

second integrating means for integrating said amplified second signal and outputting said first pulse signal;

third optical converting means for converting said third optical signal into a third frequency-modulated signal;

third frequency converting means for converting said third frequency-modulated signal into a third signal;

a third amplifier for amplifying said third signal;

waveform shaping means for producing said third pulse signal using said amplified second voltage signal; and

computing means for outputting a pulse timing signal upon receiving said third pulse signal from said waveform shaping means to said first and second converter means which respectively output said first and second digital signals to said computing means, and for determining said occurrence of partial discharge and said reason for said occurrence using said digital signal.

14. A method for detecting partial discharge generated in an interior of a gas-insulated switchgear used in a transformer installation, comprising the following steps:

detecting a first high-frequency component of a voltage applied to a conductor of said gas-insulated switchgear due to noise superimposed on said voltage;

detecting a second high-frequency component of said voltage applied to said conductor of said gas-insulated switchgear due to said partial discharge in said interior of said gas-insulated switchgear;

detecting a fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

determining whether said partial discharge has occurred, and a reason for said partial discharge, based upon a relationship between said first and second high-frequency components and said fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

detecting a zero-crossing point of said fundamental wave component, said zero-crossing point being a starting point of said voltage;

detecting respective magnitudes of said first and second high-frequency components and respective phase relationships of said first and second high-frequency component in relation to said starting point of said voltage;

determining respective first and second patterns of said first and second high-frequency components using both of said respective magnitudes of said first and second high-frequency components and said respective phase relationships of said first and second high-frequency components in relation to said starting point of said voltage;

constructing a third pattern by cancelling portions of said second pattern which overlap said first pattern;

comparing said third pattern with known patterns of said partial discharge; and

determining said partial discharge has occurred and said reason for said occurrence of said partial discharge if said third pattern corresponds with at least one of said known patterns.

15. A method for detecting partial discharge generated in an interior of a gas-insulated switchgear used in a transformer installation, comprising the following steps:

detecting a first high-frequency component of a voltage applied to a conductor of said gas-insulated switchgear due to noise superimposed on said voltage;

detecting a second high-frequency component of said voltage applied to said conductor of said gas-insulated switchgear due to said partial discharge in said interior of said gas-insulated switchgear;

detecting a fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear; and

determining whether said partial discharge has occurred, and a reason for said partial discharge, based upon a relationship between said first and second high-frequency components and said fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

wherein said determining step comprises;

detecting a zero-crossing point of said fundamental wave component, said zero crossing point being a starting point of said voltage, said voltage being a periodic voltage having a predetermined cycle;

detecting an occurrence of said first and second high-frequency components for a predetermined number of periods during said cycle of said voltage;

constructing respective first and second patterns representing respective occurrences of said first and second high-frequency components during said periods;

constructing a third pattern by cancelling portions of said second pattern which overlap said first pattern;

comparing said third pattern with known patterns of said partial discharge; and

determining said partial discharge has occurred and said reason for said occurrence of said partial discharge if said third pattern corresponds with at least one of said known patterns.

16. A method for detecting partial discharge generated in an interior of a gas-insulated switchgear used in a transformer installation, comprising the following steps:

detecting a first high-frequency component of a voltage applied to a conductor of said gas-insulated switchgear due to noise superimposed on said voltage;

detecting a second high-frequency component of said voltage applied to said conductor of said gas-insulated switchgear due to said partial discharge in said interior of said gas-insulated switchgear;

detecting a fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

determining whether said partial discharge has occurred, and a reason for said partial discharge, based upon a relationship between said first and second high-frequency components and said fundamental wave component of said voltage applied to said conductor of said gas-insulated switchgear;

frequency modulating said detected first and second high-frequency components and said fundamental wave component;

converting said frequency-modulating first and second high-frequency components and said frequency-modulated fundamental wave component into respective first, second and third optical signals;

outputting said first, second and third optical signals into a fiberoptic network;

receiving said first, second and third optical signals from said fiberoptic network and converting said first, second and third optical signals into first, second and third frequency-modulated signals;

converting said first, second and third frequency-modulated signals into first, second and third pulse signals;

outputting said third pulse signal to a computing element;

converting said first and second pulse signals into respective first and second digital signals and inputting said first and second digital signals to said computing element in response to said computing element receiving said third pulse signal; and

constructing a third digital signal by cancelling portions of said second digital signal which overlap said first digital signal, comparing said third digital signal with digital signals representing known patterns of said partial discharge, and determining said partial discharge has occurred and said reason for said occurrence of said partial discharge if said third digital signal corresponds with at least one of said digital signal representing said known patterns of said partial discharge using said computing element.