Power System Load Flow Analysis

Bulk electrical power is generated by three main methods: hydro sources, thermal stations and geothermal generating stations. Off-grid (Isolated power supplies) are obtained from diesel engine-driven generators. Others are cogeneration and wind. The power is generated at 11kV and is stepped up to high voltages of 220kV and 132 kV for transmission. The transmission voltages are to a large extent determined by system loss considerations. High voltage transmission requires larger cross-section conductors, resulting in lower resistances and, hence less energy losses on transmission lines. The load centres are usually located away from generating stations. Therefore, the power is transmitted to the load Centre, which is stepped down to 66kV or 33kV, the distribution level. The load demand determines the voltage at which power is to be supplied. The loads may be residential, industrial, or commercial, bringing about peak and off-peak load hours. Power is transmitted from low-demand areas to high-load demand in the grid network.