An improvement of voltage unbalance in a low voltage 11/0.4 kV electric power distribution network under 3-phase unbalance load condition using dynamic voltage restorer

The compensation of voltage unbalance disturbance in low voltage electric power distribution system using improved d-q-o and PI controller techniques is the focus of this paper. There are several methods to mitigate voltage unbalance. A very effective method of voltage unbalance compensation is the use of dynamic voltage restorer. Dynamic voltage restorer is a series-connected advanced power electronic custom-based tool. It is employed to mitigate voltage disturbances in low voltage electric power distribution network. Dynamic voltage restorer is installed in the network between the source voltage and the loads to correct voltage disturbances affecting the load voltage. This report presents the modelling of dynamic voltage restorer for voltage unbalance correction in a low voltage 11/0.4 kV electric power distribution network using MATLAB/Simulink Sim Power System tool box. Results obtained from simulation with distribution length 0.5 km to 5 km for 3-phase unbalanced loads are within the permissible nominal voltage tolerance of ±5% at the customer's terminal when dynamic voltage restorer is connected to the network. This is not the case when a dynamic voltage restorer is not plugged in. The results obtained demonstrate the effectiveness of this device's performance in improving voltage unbalance in a low voltage electrical power distribution from lengths 0.5 km to 5 km. The balance of the paper discusses some recommendations for an efficient, reliable and cost-effective method for improving voltage profile and reducing the voltage unbalance in 3-phase unbalance load to acceptable standards.