# Development of a Digital System for Monitoring Emergency Conditions in 20 kV Distribution Networks
## 4 Discussion  
The monitoring system proposed in this work for 20 kV power transmission lines allows for the detection of single-phase ground faults and identifies the location of the fault. The implementation of such a system eliminates the need for inspecting the entire cable line, such as underground cable channels, by focusing only on the short section where the fault occurred [16; 19]. Additionally, the zero-sequence voltage level indicates phase load imbalance in the network, as well as the presence of harmonics of the main frequency, which can result from load effects [20]. It should be noted that the zero-sequence voltage is influenced by network disturbances, expressed in rapid and short-term distortions of voltage sinusoidality and symmetry, making precise calculations under these conditions impossible due to unknown disturbance characteristics. Therefore, measuring the zero-sequence voltage level provides insights into significant load influences on network modes at measurement points and the quality of electricity. In this case, the proposed monitoring  
Figure 20: Structure of the primary segment with Internet access [11].  
system can become a part of a comprehensive power quality monitoring system for 20 kV power lines.  
It is essential to highlight that the system requires calibration and tuning for fault diagnosis modes. Such tuning can be carried out after the installation of measurement nodes on the power lines, creating a database of zero-sequence voltage measurements within the operating ranges for each installation point. One approach is to create intentional ground faults at various points along the line, where possible, and record the resulting zero-sequence voltage changes at the measurement nodes. Real ground faults should also be documented. These results will help identify patterns and create algorithms to determine the fault section between measurement nodes on the power line. In this context, using an artificial intelligence system capable of identifying patterns would allow for more accurate ground fault location based on the developed database [21].  
The measurement module must be energy efficient, remaining in a standby mode during normal line operation. The module can be programmed to transmit measurement results only when the voltage exceeds a set threshold, indicating a fault. This threshold can be programmed individually for each measurement node based on the characteristics and operating conditions of the monitoring site. The beginning of data transmission signals the occurrence of a fault in the monitored section. In standby mode, the module's functionality is periodically checked by a server request for the status of the power source and current measurements. The standard battery capacity ensures the monitor's functionality for three years.  
To more accurately determine fault locations, the digital version of the harmonic amplitude comparison method for the fundamental frequency can be used [1,21,22]. This requires spectral analysis of the induced voltage using digital filters. This method is quite complex and involves the digitalization of monitoring processes, necessitating specialized literature review and technical knowledge in areas such as mathematical modeling and electrical process analysis, as well as digital information transmission technologies. To implement this complex method, zero-sequence voltage spectrum data must be transmitted from the measurement node to the server, where spectral analysis can be performed. The author plans to develop a series of articles on this topic, proposing innovations for further development and improvement of the 20 kV power line monitoring system.