Method for identifying one or more simultaneously occurring partial discharge sources

• US 9,835,674 B2
• Filed: 09/17/2012
• Issued: 12/05/2017
• Est. Priority Date: 09/16/2011
• Status: Active Grant

• Current Assignee: Olaf Rudolph
• Original Assignee: Olaf Rudolph
• Inventors: Rudolph, Olaf
• Primary Examiner(s): Astacio-oquendo, Giovanni
• Application Number:
  US14/345,397
• Publication Number:
  US 20140340096A1
• Time in Patent Office: 1,905 Days
• Field of Search: 324536, 324500, 324512
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks
• 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 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083
• CPC Class Codes: G01R 31/1281 of liquids or gases

Abstract

A method for identifying one or more simultaneously occurring partial discharge sources from partial discharge measurement signals of an electrical device to which an AC voltage is applied includes determining area parameters of at least one enclosed area of partial discharge pulse matrix arrays. For each enclosed area of partial discharge pulse matrix arrays, area parameters of the enclosed area of partial discharge pulse matrix arrays are compared to predetermined rule sets. Predetermined fault rules are applied which allocate characteristic partial discharge pulse area basic forms and characteristic combinations of partial discharge pulse area basic forms to known partial discharge sources, to the ascertained partial discharge pulse area basic forms in order to determine those partial discharge sources which have rendered the corresponding partial discharge pulses.

Claims

1. A method comprising:

obtaining partial discharge measurement signals of an electrical device to which an AC voltage is applied, said electrical device selected from the group consisting of a gas-insulated system, a high-voltage generator, a transformer, an electrical high-voltage power line, and an electrical cable; and

identifying one or more simultaneously occurring partial discharge sources from said partial discharge measurement signals of said electrical device, the identifying comprising;

on the basis of a frequency matrix in a computer system into which measured partial discharge pulses are entered as partial discharge pulse matrix arrays according to a detected pulse amplitude and to a detected phase position and in which partial discharge pulse matrix arrays are allocated to at least one enclosed area of partial discharge pulse matrix arrays, the computer system determining area parameters of the at least one enclosed area of partial discharge pulse matrix arrays;

the computer system comparing, for each enclosed area of partial discharge pulse matrix arrays, area parameters of the enclosed area of partial discharge pulse matrix arrays to predetermined rule sets, with each rule set corresponding to a characteristic partial discharge pulse area basic form; and

allocating, for each enclosed area of partial discharge pulse matrix arrays, that rule set to the enclosed area which best corresponds to the enclosed area, such that one partial discharge pulse area basic form is allocated to each enclosed area of partial discharge pulse matrix arrays; and

the computer system applying predetermined fault rules, which allocate characteristic partial discharge pulse area basic forms and characteristic combinations of partial discharge pulse area basic forms to known partial discharge sources, to ascertained partial discharge pulse area basic forms in order to determine those partial discharge sources which have rendered corresponding partial discharge pulses,

wherein the area parameters of the at least one enclosed area of partial discharge pulse matrix arrays are at least one area parameter from the following group;

area share=number of the partial discharge pulse matrix arrays in an enveloping rectangle / number of all matrix arrays in the enveloping rectangle;

aspect ratio of the enveloping rectangle=vertical extension / horizontal extension of the enveloping rectangle;

free corners of the enveloping rectangle=corners of the enveloping rectangle at which all matrix arrays are free;

free side centers of the enveloping rectangle=side centers of the enveloping rectangle at which all matrix arrays are free;

curvature to the left;

curvature to the right;

curvature on the top;

curvature on the bottom;

vertical symmetry=symmetry around the vertical center axis; and

horizontal symmetry=symmetry around the horizontal center axis.

2. The method according to claim 1, wherein said frequency matrix, into which measured partial discharge pulses are entered as partial discharge pulse matrix arrays according to the detected pulse amplitude and to the detected phase position, is first formed, and/or wherein, in the frequency matrix, partial discharge pulse matrix arrays are allocated to at least one enclosed area of partial discharge pulse matrix arrays.

3. The method according to claim 1, wherein the partial discharge pulse matrix arrays in the frequency matrix have respective chain lengths and are allocated to at least one enclosed area of partial discharge pulse matrix arrays on the basis of their chain lengths.

4. The method according to claim 3, wherein, when allocating the partial discharge pulse matrix arrays in the frequency matrix to at least one enclosed area of partial discharge pulse matrix arrays, at first the properties length of contiguous partial discharge pulse matrix arrays in the horizontal direction, length of contiguous partial discharge pulse matrix arrays in the vertical direction, length of contiguous partial discharge pulse matrix arrays in the diagonally ascending direction and length of contiguous partial discharge pulse matrix arrays in the diagonally descending direction are allocated for each partial discharge pulse matrix array.

5. The method according to claim 4, wherein, when allocating the partial discharge pulse matrix arrays in the frequency matrix to at least one enclosed area of partial discharge pulse matrix arrays, the property length of contiguous partial discharge pulse matrix arrays in the horizontal direction is put into relation with the property length of contiguous partial discharge pulse matrix arrays in the vertical direction for each partial discharge pulse matrix array in order to determine the deduced property cross aspect, and/or wherein, for each partial discharge pulse matrix array, the property length of contiguous partial discharge pulse matrix arrays in the diagonally ascending direction is put into relation with the property length of contiguous partial discharge pulse matrix arrays in the diagonally descending direction in order to determine the deduced property diagonal aspect.

6. The method according to claim 5, wherein, when allocating the partial discharge pulse matrix arrays in the frequency matrix to at least one enclosed area of partial discharge pulse matrix, the properties cross aspect and diagonal aspect are used for adjacent partial discharge pulse matrix arrays in order to determine whether or not adjacent partial discharge pulse matrix arrays belong to the same enclosed area.

7. The method according to claim 5, wherein, when allocating the partial discharge pulse matrix arrays in the frequency matrix to at least one enclosed area of partial discharge pulse matrix arrays, the deviation of a partial discharge pulse matrix array from the horizontally, vertically and diagonally adjacent partial discharge pulse matrix arrays is determined in pairs for all partial discharge pulse matrix arrays, wherein the deduced properties cross aspect and diagonal aspect are used for this determination of similarity.

8. The method according to claim 6, wherein, when allocating the partial discharge pulse matrix arrays in the frequency matrix to at least one enclosed area of partial discharge pulse matrix arrays, the cross deviation for each partial discharge pulse matrix array is determined according to the following formula

9. The method according to claim 8, wherein, when allocating the partial discharge pulse matrix arrays in the frequency matrix to at least one enclosed area of partial discharge pulse matrix arrays, the horizontally, vertically or diagonally adjacent partial discharge pulse matrix array having the greatest still admissible deviation below a predetermined maximum deviation is determined for each partial discharge pulse matrix array.

10. The method according to claim 9, wherein the partial discharge pulse matrix arrays in the frequency matrix are allocated to at least one enclosed area of partial discharge pulse matrix arrays by sequentially analyzing, for each partial discharge pulse matrix array, the partial discharge pulse matrix array and the horizontally, vertically or diagonally adjacent partial discharge pulse matrix array having the greatest still admissible deviation below a predetermined maximum deviation;

and by, if both partial discharge pulse matrix arrays have not yet been assigned an area number, allocating the partial discharge pulse matrix array to a new area number;

if the area number of the adjacent partial discharge pulse matrix array is greater than the area number of the partial discharge pulse matrix array, allocating the area number of the adjacent partial discharge pulse matrix array to the partial discharge pulse matrix array; and

, if neither of the two conditions is met, maintaining the area number of the partial discharge pulse matrix array and continuing with the allocation of the next partial discharge pulse matrix array.

11. The method according to claim 10, wherein said allocation is repeated for all partial discharge pulse matrix arrays until the area numbers no longer change.

12. The method according to claim 10, wherein, when allocating the partial discharge pulse matrix arrays in the frequency matrix to at least one enclosed area of partial discharge pulse matrix arrays, those matrix arrays which are not partial discharge pulse matrix arrays are not considered.

13. The method according to claim 10, wherein a partial discharge pulse matrix array is only allocated if the deviation for the considered partial discharge pulse matrix array is below a predetermined maximum deviation value, which ranges between 0.6 and 0.8 and is preferably approx. 0.7;

otherwise, the procedure continues with the allocation of the next partial discharge pulse matrix array.

14. The method according to claim 1, wherein, when allocating the partial discharge pulse matrix arrays in the frequency matrix to at least one enclosed area of partial discharge pulse matrix arrays, all partial discharge pulse matrix arrays the area of which is too small are removed, wherein an area is in particular too small if it comprises less than 10 partial discharge pulse matrix arrays and/or if its horizontal or vertical extension is below 8 partial discharge pulse matrix arrays.

15. The method according to claim 1, wherein, in the step of comparing area parameters of the enclosed area of partial discharge pulse matrix arrays to predetermined rule sets for each enclosed area of partial discharge pulse matrix arrays, a probability value is allocated to each enclosed area, said probability value corresponding to the probability of the conformity of the enclosed area with the partial discharge pulse area basic form of a characteristic partial discharge source signal.

16. The method according to claim 15, wherein the probability of the conformity of the actual value with the target value is calculated by means of a continuous function, and wherein at least one of the functions