Voltage stabilization on medium voltage distribution lines using fly wheels.

Abstract

The distribution network is characterized by some long medium voltage lines that tend to have low voltage levels in case of heavy loading and high voltage levels when lightly loaded. With the low voltage levels, this is mainly due to the high voltage drop along the long lines as a result of an increase in the load whereas for lightly loaded lines, the receiving end voltages are found to increase even above the sending end voltages leading to Ferranti effect. With low voltages however, power is not fully utilized hence leading to commercial losses by the utility company. Since equipment are designed to work at a particular voltage range, high voltages could lead to damage of equipment connected at the receiving end. The project in question intends to provide a solution by designing of a flywheel energy storage system to stabilize both abnormally high and low voltages by injecting or absorbing reactive power from the medium voltage grids. The case studies at hand are the Hoima Busunju 33kv feeder and Jinja Marble rated 33kv.In both scenarios, the flywheel system is placed at the load/ receiving end of the medium. The data regarding the parameters were obtained from UMEME limited Uganda and visualized in ArcGIS software and clearly highlighted. Both the network and the flywheels were modelled in MATLAB/Simulink with the flywheel consisting mainly of a grid and machine side convertor, asynchronous machine that acts as both a motor and generator in the charging and discharging mode respectively. The network performance was assessed with and without the flywheel by considering not just the voltage profile at each bus, but also the network losses for each scenario and the Data tabulated including the percentage changes involved. It was observed in both scenarios that voltages were normalized and reduction of line losses which contribute to technical losses for the utility and quality power for the consumers reduced.