Active Fault Detection Device for LV Electrical Installations with Goertzel-Based Impedance Estimation and IoT Connectivity

An active (harmonic-injection based) fault detection device, relevant to low voltage electrical installations is studied in this paper. This compact and flexible device is compatible with TN/TT earthing systems, and it is capable of detecting power theft (i.e., via meter tampering), neutral conductor loss at the upstream network and unintentional islanding. A 12th order zero-sequence voltage harmonic component is injected -via a low-power H-bridge inverter along with a current transformer (CT), in series with the grid voltage, whereas the corresponding harmonic current is measured, to estimate the impedance. The well-established, robust and fast Goertzel algorithm is selected as the impedance monitoring method, to effectively diagnose any fault. Finally, the device features Internet of Things connectivity capabilities, as it employs the ESP32 microcontroller, facilitating its communication and data exchange capabilities with the installation meter, as well as with various smart home devices.