Abstract
Air-insulated switchgear cabinet plays a critical role in entire power transmission and distribution system. Its stability directly affects the operational reliability of the power system. And the on-line gas detection method, which evaluates the insulation status of insulation equipment by detecting the decomposition components of filled air in cabinet, becomes an innovative way to ensure the running stability of air-insulated switchgear cabinet. In order to study the characteristic gas types and production regularity of decomposition components under partial discharge, three insulation defects: needle-plate, air-gap and impurity defect are proposed to simulate the insulation defects under partial discharge in air-insulated switchgear cabinet. Firstly, the generation pathways and mechanism of composition components are discussed. Then CO and NO2 are selected as the characteristic decomposition components to characterize the partial discharge due to their high concentration and chemical stability. Based on the different change regularity of CO and NO2 concentration under different insulation defect, it provides an effective way to evaluate and predict the insulation defect type and severity in the field.
Highlights
With the development of power transmission and distribution system, it brings forward higher requirement for the running stability of insulation equipment.[1,2] Air-insulated switchgear, which directly delivers electric power to terminal, is the most commonly used power transmission and distribution equipment.[3,4] Air-insulated switchgear cabinet is a closed equipment integrated by circuit breaker, isolating switch load switch, mutual inductor and other protection device.[5]
CO and NO2 are selected as the characteristic decomposition components to characterize the partial discharge due to their high concentration and chemical stability
Various current detection methods: pulse current, ultra-high-frequency electromagnetic wave detection (UHF), transient enclosure voltage (TEV), optoacoustic detection and chemical gas sensor detection methods have been performed to detect the partial discharge according to the physical signals produced along with the partial discharge.[15,16,17,18,19]
Summary
With the development of power transmission and distribution system, it brings forward higher requirement for the running stability of insulation equipment.[1,2] Air-insulated switchgear, which directly delivers electric power to terminal, is the most commonly used power transmission and distribution equipment.[3,4] Air-insulated switchgear cabinet is a closed equipment integrated by circuit breaker, isolating switch load switch, mutual inductor and other protection device.[5]. To protect the stability of air-insulated switchgear cabinet from partial discharge, it is critical to find out the insulation defects existed in air-insulated switchgear cabinet in time These inevitable insulation defects can be caused by metal protrusion defect, loose-contact defect and impurity defect during the preparation and long term running process.[12,13,14] Currently, various current detection methods: pulse current, ultra-high-frequency electromagnetic wave detection (UHF), transient enclosure voltage (TEV), optoacoustic detection and chemical gas sensor detection methods have been performed to detect the partial discharge according to the physical signals produced along with the partial discharge.[15,16,17,18,19] pulse current method is only fit for offline detection, and UHF and TEV method are affected by ambient interference signal. This decomposition component detection method provides a new way to develop on-line monitoring system used for other gas-insulated equipment
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