Verification of low-frequency signal injection method for earth-fault detection

TL;DR

This paper investigates a low-frequency signal injection method for detecting earth faults in medium-voltage unearthed networks, combining simulations and experimental validation to improve fault detection speed.

Contribution

It demonstrates the feasibility of using inductive voltage transformers for signal injection in MV networks, supported by both EMT simulations and experimental tests.

Findings

Successful simulation of signal injection in MV networks

Experimental validation of earth-fault detection method

Potential for faster fault localization in industrial power systems

Abstract

Unearthed neutral is commonly used in networks which require continuous power supply. This is common in MV circuits of industrial and power plants. Unearthed networks can remain in operation during an earth-fault, but fast determination of the faulty line is key for prevention of further fault escalation. Signal injection is one of the fault location methods often used in LV unearthed networks. The possibility of applying this method in MV networks depends on how to inject the signal into unearthed phases. In such networks, it is possible to use a group of three inductive voltage transformers (IVTs) for signal injection. After the simulations have shown promising results of signal injection and earth-fault detection in MV network, an experimental test was performed. This paper describes the experimental setup and shows the measurement results of signal injection method at MV level supported by EMT simulations.