System and method for assessing power transformers

Patent metadata

Field	Value
Publication number	US-10488384-B2
Application number	US-201414534593-A
Country	US
Kind code	B2
Filing date	Nov 6, 2014
Priority date	Nov 6, 2013
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

A system and method for evaluating power transformers is disclosed. The method includes the steps of acquiring data representing one or more parameters of a power transformer, using rules to derive one or more broad physical conditions of the power transformer from the acquired data, and using the broad physical conditions as inputs to compute a plurality of indices. Each index represents a category of failure mechanisms of the power transformer. The method further includes the steps of using the plurality of indices to determine a corrective action and performing the corrective action on the power transformer.

First claim

We claim:

1. A method of maintaining a power transmission system of the type including a plurality of interconnected power transformers, comprising the steps of:
(a) acquiring data representing one or more parameters of a power transformer, wherein the step of acquiring data includes the step of acquiring dissolved gas analysis data from a sample of oil contained in the power transformer;
(b) analyzing the acquired data using pre-defined rules to derive one or more broad physical conditions for each of the plurality of power transformers to compute a plurality of indices representing failure mechanisms of the power transformers, wherein the plurality of indices include one or more abnormal indices, a normal degradation index, and an oil quality index;
(c) using the dissolved gas analysis data to compute the normal degradation index for each of the plurality of power transformers;
(d) identifying a subset of the plurality of power transformers having a normal degradation index value greater than 0.60; and
(e) replacing the subset of power transformers.

2. The method according to claim 1 , wherein the parameters are selected from the group consisting of nameplate data, dissolved gas analysis history, oil quality history, and furans.

3. The method according to claim 1 , wherein the broad physical conditions include partial discharge, low-level arcing, high-level arcing, temperatures less than 300 degrees Celsius, temperatures greater than 300 degrees Celsius and less than 700 degrees Celsius, and temperatures greater than 700 degrees Celsius.

4. The method according to claim 1 , wherein the broad physical conditions include assessment of paper involvement.

5. The method according to claim 1 , wherein the one or more abnormal indices is selected from the group consisting essentially of abnormal thermal index, abnormal electrical index, and abnormal core index.

6. The method according to claim 1 , further including the step of assigning failure mechanisms to each of the one or more abnormal indices and assigning a belief to each of the individual failure mechanisms.

7. The method according to claim 6 , further including the step of determining a maximum belief assigned to a failure mechanism for each abnormal index and assigning the maximum belief to that abnormal index.

8. The method according to claim 7 , wherein if any of the one or more abnormal indices have a maximum belief greater than 0.5, then an investigation and corrective action is taken.

9. The method according to claim 1 , wherein if the normal degradation index is greater than 0.25 then an indication of potential degradation exists and further investigation and replacement action is taken.

10. The method according to claim 8 , wherein the corrective action is selected from the group consisting of changing oil sampling frequency, installing online monitoring, electrical testing, and conducting an internal inspection.

11. A system configured to evaluate and diagnose a condition of a power transformer contained in a power transmission system, comprising:
(a) a computing device configured to provide a user interface to allow a user to input data and execute rules to analyze the data; and
(b) a plurality of modules executed by the computing device, the modules being configured to conduct various stages of analysis on one or more power transformers, the modules comprising:
(i) an input module executed by the computing device to allow a user to input data gathered for each power transformer being analyzed;
(ii) an analysis engine module executed by the computing device in response to the data being entered into the system, the analysis engine executing pre-defined rules to determine indices, wherein the analysis engine module assigns beliefs to pre-determined power transformer failures and assigns individual failures to a pre-determined index, wherein the pre-determined indices include an abnormal index, a normal degradation index; and an oil quality index; and
(iii) an output module executed by the computing device in response to the analysis engine module determining indices, the output module displaying results of the analysis engine module for a user to view and prompting the user to perform an action representative of a value assigned to the indices.

12. The system according to claim 11 , wherein each of the beliefs have a value between −1 and +1.

13. The system according to claim 12 , wherein the analysis engine module assigns the maximum belief for the power transformer failures contained in a pre-determined index to the pre-determined index and outputs the maximum belief to the output module for viewing by a user.

14. The system according to claim 11 , wherein the abnormal index includes an abnormal thermal index, an abnormal electrical index, and an abnormal core index.

15. The system according to claim 14 , wherein if a maximum belief assigned to a failure mechanism for each abnormal index is greater than 0.5 then the computing device prompts the user to investigate and take corrective action.

16. The system according to claim 14 , wherein if the maximum belief assigned to the normal degradation index is greater than 0.25 then the computing device provides an indication that potential degradation exists and prompts the user to investigate and replace the power transformer.

Assignees

• Electric Power Res Institute Inc

Inventors

• Desai Bhavin N
• Raymond Timothy

Classifications

• G01R31/62 Primary

  Testing of transformers · CPC title

• G01N33/26 Primary

  Oils; Viscous liquids; Paints; Inks (G01N33/22 takes precedence) · CPC title

• G01N33/2841

  Gas in oils, e.g. hydrogen in insulating oils · CPC title

• G01R31/027

  Physics · mapped topic