A Novel Method for Seamless Closed-Loop Load Transfer of Low Voltage Distribution Network

This paper presents a novel seamless closed-loop load transfer device (SCLTD) of low voltage distribution network, which is capable of realizing three seamless operations: 1) loop closing, 2) load transfer, and 3) disconnection from the grid. In the proposed circuit configuration, an injected voltage source is connected to two low voltage bus bars. Therefore, closed-loop current can be controlled flexibly by regulating this voltage source. The system can be applied to adjacent substations to carry out closed-loop load transfer operations. In the proposed configuration, the voltage source is paralleled with the contact switch and thus can be bypassed to realize the disconnection of the SCLTD from the grid. Furthermore, this paper presents an advanced control strategy for seamless transfer among three operating modes, which eliminates the voltage oscillation and current impact due to the switching of operating modes. The proposed configuration and the designed control strategy are validated in a simple two-bus system via MATLAB/Simulink.