Control Relay Circuit of Dynamic Load Balancer on Medium Voltage Distribution Line

The distribution of electricity is commonly done in 3 phase radial network or loop type system. The voltage varies from 34 KV (Kilovolts) down to 13.8 or 11 KV. The single-phase transformers are evenly distributed or connected along the system, that causes unbalance loading to the system as the load behavior of the customers is dynamically changing. Due to these unbalance loading, the voltage at the sending end is adjusted by the distribution operator to compensate for the unbalance. The voltage regulator (VR) used has a maximum tap setting capacity that when the unbalance occurs and beyond the capability of the VR, the unbalance voltage will be imminent. Therefore, the operator has no option, although this can rarely happen, but to change the physical connection of a few single-phase transformers connected to the system to correct the unbalances. Power interruption is needed to execute the desired connection of the single-phase transformer, and the duration varies depending on the type of connector used. Hotline clamps are commonly used along overhead lines but sometimes wedge type or clamp connector is used. The process of removing and transferring the transformer leads and, in most cases, the primary leads are either long or short to the new phase and therefore is not efficient and the safety of personnel is always in question as this is done with the live line procedure when hot line clamp was utilized. This research paper investigated the potential of a new hardware to be permanently connected to all the single-phase transformers that can facilitate the needed changing of phase connection should the unbalance in the system be beyond the VR tap setting limits and the on-load tap changer (OLTC) of the substation transformer. The aim of this new hardware design is to have a fast and efficient way to transfer the phase connection of single-phase transformers to any desired phase (AB, BC, or CA). The research is currently limited to the control unit using electromechanical relays and timers.