Transient Residual Voltage Influence on the Dynamic Load Transfer

The successful operation of back-up supply sources in the case of dynamic loads transfer in industrial electricity supply installation is mainly depending on the mitigation of the residual voltage that appears in fault scenarios that result in losing supply from the main grid. The decrease of the interval of presence of residual bus voltage depends highly on the local load and the network configuration. A high time constant (seconds) of the decreasing residual voltage can lead to the disconnection of critical consumers. In this paper, it is presented a simple, cost-effective method for dynamic load transfer that can replace the Motor Bus Transfer approach. The validity of the method is tested on a real large industrial site from Romania. The case study shows that the proposed approach can achieve a voltage return time of around 750 ms.