Analysis technology and application case of dissolved gases in power transformer oil

Analysis technology and application case of dissolved gases in power transformer oil

1、 Technical Overview

The analysis technology of dissolved gases in power transformer oil is a method of determining whether there is a fault and the type of fault inside the transformer by detecting the composition and content of dissolved gases in the transformer oil. This technology is mainly based on the correspondence between the types of dissolved gases in oil and internal faults, and is analyzed using gas chromatography. Based on the composition of gases and the content of various gases, faults inside transformers can be diagnosed, including the nature, approximate location, severity, and development trend of the faults.

2、 Technical application cases

Case 1: Sudden increase in H2 content in 110kV transformer of a certain power plant

After a 110kV transformer was put into operation in a power plant, oil chromatography analysis found that the H2 content suddenly increased and exceeded the limit. After continuous monitoring and power-off maintenance, it has been confirmed that the cause of the sudden increase in H2 is due to dehydrogenation reaction, which may be related to the materials used in the manufacturing process of the transformer. By contacting the manufacturer, it was confirmed that the transformer uses a new type of steel, therefore it is judged that there is no fault problem with the transformer itself. This case demonstrates that the analysis technology of dissolved gases in oil can timely detect abnormal situations inside transformers and provide strong basis for fault diagnosis.

Case 2: Sudden increase in acetylene content in transformer oil of a 220kV substation of a certain power supply company

The main transformer of a 220kV substation within the jurisdiction of a certain power supply company experienced two sudden increases in dissolved gases in transformer oil within a year. After discovering the sudden increase in acetylene content for the first time, continuous testing revealed that the acetylene content continued to increase. In the second sudden increase in gas content, H2 and C2H2 showed the largest increase. After inspecting the suspension cover, it was found that there were obvious discharge marks on the outer insulation board of the winding, and a rubber strip that caused the discharge was found. After removing the rubber strip, the transformer resumed normal operation. This case demonstrates that the analysis technology of dissolved gases in oil can accurately diagnose discharge faults inside transformers and guide maintenance personnel to carry out targeted treatment.

3、 Technical application precautions

When analyzing dissolved gases in oil, attention should be paid to selecting appropriate characteristic gases and ratio methods for judgment, and comprehensive analysis should be carried out based on the actual situation of the transformer.

The function of attention value is to provide a signal that attracts attention, but it is not the only criterion for classifying fault types. The gas content exceeding the attention value does not necessarily indicate equipment malfunction, and sometimes the gas content does not exceed the attention value, but the growth rate is rapid, which should also be noted.

In practical applications, factors such as equipment type, load situation, fault type, volume and aging degree of insulation materials used should be comprehensively considered to accurately evaluate the gas production rate.

4、 Conclusion

The analysis technology of dissolved gases in power transformer oil is an effective fault diagnosis method, which can timely detect abnormal situations inside the transformer and accurately diagnose the type of fault. Through the verification of practical application cases, this technology provides strong guarantees for the safe and stable operation of power equipment.