Abstract
The internal insulation condition of capacitor voltage transformers (CVTs) is a key influence factor that affects their measurement performance and safe operation. However, the internal insulation would age along with long-time operation and degrade due to environmental factors, and once the insulation degradation grows, serious damage and even explosion may happen in CVTs; hence, it is necessary to monitor the internal insulation condition of CVTs, and the fault type and fault degree need to be identified. In this paper, a data-driven internal insulation condition identification method for CVTs is proposed. Both the amplitude and phase of the output voltage of CVTs are collected, and then, recognition models based on the combination of the output voltages and distribution topology of CVTs in substations are built. A possibilistic fuzzy clustering method is used to monitor the internal insulation condition of CVTs, and different types and different degrees of insulation faults could be identified effectively. Finally, the proposed method is verified in several cases; not only the preset typical faults in the method could be identified effectively but also the faults beyond the preset faults could be diagnosed.
Highlights
The capacitor voltage transformers (CVTs) have already been the most widely used voltage transformer in the high voltage (HV) and ultra-high voltage (UHV) power system 1–3
This method is based on the possibilistic fuzzy c-means clustering algorithm (PFCM), and it combines the physical model of the insulation structure and the output voltage datasets of groups of CVTs, the insulation condition of CVTs and the possibility of some typical faults occurrence are given by applying the PFCM to the output voltage datasets
With the increment of the voltage level of modern power system, the inaccuracy measurement, the power failure and even the explosion caused by the insulation faults of CVTs would lead to serious consequences
Summary
The capacitor voltage transformers (CVTs) have already been the most widely used voltage transformer in the high voltage (HV) and ultra-high voltage (UHV) power system 1–3. The internal structure of CVTs is much more complicated compared with the conventional electromagnetic potential transformers (PTs), which leads to worse long-term stability and susceptibility to external electromagnetic interference 4,5. The insulation of CVTs is prone to be aged after long-term operation, and the over voltage in the power system and the partial discharge in the CVT may cause irreversible damage to the insulation of CVTs 6. A CVT whose insulation is faulted cannot convert the primary voltage into secondary voltage correctly, even worse, explosion may occur in CVTs, which is a threat to the safety of the power system.
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