SYSTEM AND METHOD FOR ASSESSING FAULTY POWER-LINE INSULATOR STRINGS

• US 20130179099A1
• Filed: 12/24/2012
• Published: 07/11/2013
• Est. Priority Date: 01/08/2012
• Status: Active Grant

• Current Assignee: Megger Grid Analytics Limited
• Original Assignee: Metrycom Communications Ltd.
• Inventors: KNIJNIK, ROMAN, KOTTICK, DANIEL, MASLOVSKI, LEONID, WOLFSON, EDUARD, FRENKEL, LIRON
• Granted Patent: US 9,244,114 B2
• Time in Patent Office: Days
• US Class Current: 702/58
• CPC Class Codes: G01R 31/088 Aspects of digital computing
• CPC Class Codes: G01R 31/1245 of line insulators or spacers, e.g. ceramic overhead line cap insulators; of insulators in HV bushings

Abstract

A system for the detection of discharges over high voltage power-line insulator strings of an electrical grid. A sensor unit is deployed on a non conducting cable of the grid. The sensor feeds an array of band cut-off filters receiving each signals from said at least one sensor unit. An analogue processor is associated with each of the band cut-off filters associated each with a current peak detector. An ADC unit is associated with each one of said analogue processors. In addition a digital processor is provided for calculating data received from each one of the ADCs and one radio transmitter unit sends data to a gateway of a network. A digital processor is adapted to send data processed based on the output of the ADCs, to the radio transmitter for conveying the data to processor associated with a WAN.

Claims

1. A system for the detection of discharges over high voltage power-line insulator strings of an electrical grid in which wires are deployed supported by towers, said device comprising:

at least one sensor unit associated with a non conducting wire of said grid;

an array of at least one band cut-off filter (BCOF) receiving each signals from said at least one sensor unit;

an analogue processor per each of said at least one BCOFs each of which having associated with a peak detector;

analogue to digital converter (ADC) unit per each one of said analogue processors;

a digital processor for calculating data received from each of said at least one of said ADCs;

a communications link for sending data to a gateway of a network, and

wherein said digital processor is adapted to send data processed based on output of said ADCs, to a server for further processing.

2. A system as in claim 1, wherein said non -conducting wire is a ground wire.

3. A system as in claim 1, wherein said non -conducting wire is a wire connecting between a tower and the ground.

4. A system as in claim 1, wherein at least said analogue and said digital processors are power fed by currents induced in a non conducting wire.

5. A system as in claim 1, wherein said communications link is radio link.

6. A system as in claim 4 wherein said radio link is multi-hop link.

7. A system as in claim 1 wherein said at least one sensor and said array of BCOFs and said analogue processors and said ADC converters and digital processor all relating to the same sensor are packaged together;

8. A method of assessing the level of partial discharges of strings of insulators deployed on an electric grid, said method comprising the steps of:

sensing currents over a non conducting cable of said electric grid by sensing units deployed along said grid;

feeding said currents to an array of BCOFs for splitting said currents to respective frequency bands;

performing current peak detection and assessment per each of said frequency bands;

forming a histogram representing the amplitude distribution of voltage peaks per a predetermined period of time, taken all over a predetermined period of time;

repeating said measurements of voltage and peak detecting over a larger period of time;

finding the peak values of higher percentiles of frequency distribution of measured BCOF to obtain a value, and comparing said value to correlate with a threshold level of partial discharge.

9. A method as in claim 8 wherein values of said higher percentiles are divided by the value of the 50% percentile comparing to the threshold.

10. A method as in claim 8 wherein said threshold is dynamic and occasionally updated.

11. A method as in claim 8 in which optical inspection revealing quantitative coverage of the insulator strings by partial discharges is correlated with said thresholds.

12. A method of assessing the distance from a site in which discharging string of insulators takes place on an electric grid, said method comprising the steps of:

sensing currents over a non conducting cable of said electric grid by sensing units deployed along said grid;

feeding said currents to an array of BCOFs for splitting said currents to respective frequency bands;

performing current peak detection and assessment per each of said frequency bands;

forming a histogram representing the amplitude distribution of voltage peaks per a predetermined period of time, taken all over a predetermined period of time;

repeating said measurements of voltage and peak detecting over a larger period of time;

dividing the peak level associated with a high frequency BCOF by the peak level associated with low frequency BCOF to obtain a value, and

classifying said value to correlate with a specific distance of a string of insulators.