The effects of branches on condition related signals in Low Voltage underground power systems

Low Voltage (LV) underground power cables are a valuable asset for grid operators. Condition monitoring is under investigation, especially related to intermittent faults. These events may be accompanied or preceded by discharge current signals, which could be measured in substations nearby. To estimate wether such signals are detectable in practical situations, a high frequency model of the grid is constructed. This paper reports on modeling of a feeder section representing a single branch connection a customer to the main LV cable. The cables are modeled as a multi-conductor transmission line, whereas the joint itself is represented by lumped parameters. The joint parameters were measured separately on a typically applied joint type. The network section was simulated considering typical cable types for the service cable and the main cable. Measurements on the actual feeder section are compared to the simulation results, showing good agreement. This model is an initial step to simulate cable condition related signals in a complete LV feeder.