Modeling and Simulation of a Load Transfer Controller for Uninterrupted Operation of Low-Voltage Distribution Grids

Recently, the uninterrupted operation of low-voltage distribution grids has been paid great attention to. The load transfer technique during equipment maintenance, peak load period, and grid construction becomes a determinant factor to realize uninterrupted operation. This paper designs and analyzes a load transfer controller (LTC), which can be connected to two adjacent substations to carry out load transfer operation. Additionally, the power flow and the power rating analysis of an LTC are discussed in detail. In the topology of an LTC, one series voltage source converter (VSC) and one shunt VSC share the common DC bus. The shunt VSC which acts as a unity power factor rectifier is used to keep the DC bus voltage constant. The series VSC acting as a series voltage compensator is responsible for the connection and disconnection of the device and the load transfer. Extensive simulations on a two-bus system equipped with an LTC under the conditions of different voltage differences and phase-angle differences confirm the theoretical studies of an LTC.