Double Line-to-Ground Faults Detection Method in DC-AC Converters

Numerous electrical machines use power converters for their efficient operation. However, their insulations experience a fast deterioration due to high frequency electrical stresses. This loss of insulation can lead into ground faults, which are the most common electrical faults. Convectional protec...

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Bibliographic Details
Published in:IEEE transactions on industry applications 2023-01, Vol.59 (1), p.332-344
Main Authors: Guerrero, Jose Manuel, Navarro, Gustavo, Mahtani, Kumar, Platero, Carlos Antonio
Format: Article
Language:English
Subjects:
AC-DC power converters
Alternating current
Circuit faults
Commutation
Current measurement
electrical fault detection
Electrical faults
Electrical grounding
Electrical measurement
electrical safety
Fault currents
Fault detection
fault diagnosis
Faults
Frequency analysis
Frequency domain analysis
Grounding
High resistance
Insulation
Phasors
Power converters
Relays
Resistors
Voltage measurement
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Summary:Numerous electrical machines use power converters for their efficient operation. However, their insulations experience a fast deterioration due to high frequency electrical stresses. This loss of insulation can lead into ground faults, which are the most common electrical faults. Convectional protection relays are not specifically designed to protect electrical drives. Moreover, relays' malfunction could be provoked because of commutation noises, or DC and AC fault current's components influence in their measurement. Therefore, if the fault is not detected in time, it can be developed into a more severe fault. This paper proposes a detection method for high resistance double line-to-ground faults in electrical drives based on a grounding resistor placed in the midpoint of the DC side. The method has been developed for DC/AC systems and it is based on the voltage measurement in the grounding resistor and in the AC phases. Afterwards, performing a frequency domain analysis of the grounding resistor voltage and comparing its fundamental harmonic phase differences with the AC voltage phasors, the double line-to-ground fault incipient zone (DC and/or AC) can be detected, and also, the DC faulty pole or AC faulty phase can be discerned. The method has been verified through computer numerous simulations and experimental tests in a 140 kW power converter, obtaining satisfactory results in the fault detection. However, the exact location of each ground fault still being incognita.
ISSN:0093-9994
1939-9367
DOI:10.1109/TIA.2022.3212348