Contingency analysis of the electricity transmission network of Uganda

Abstract

The operation of the Ugandan Grid is based on the Single outage Contingency criterion. Contingency is the failure of any power system equipment. Contingency analysis is the study of the outage of the components. Uganda’s transmission network has not met the n-1 contingency criterion as evidenced by the outages following the failure of some lines mainly due to faults and vandalism. Also, operating Karuma at full capacity or failure of a unit(s) of Karuma HPP dur ing operation will have impacts on the grid. The main aim of the project is to study the impacts of the loss of one or more units of Karuma on the grid and assess the impacts of the failure of the most critical transmission lines on the line power flows and voltage performance of the network and provide recommendations for long-term planning of the network. The case study was the Transmission Network of Uganda and the network data was collected from Uganda Electricity Transmission Company Limited (UETCL). The network was modeled in DigSILENT Power Factory 15.1 and load flow analysis and contingency analysis were performed to identify the most critical lines to the operation of the grid and the impacts of failure of these extremely important lines were analyzed individually. From the analysis of the results, the most critical transmission lines to the operation of the network are 220kV Kawanda-Masaka lines, 220kV Bujagali-Kawanda lines, 132kV Owen Falls-Lugogo lines, and 132kV Owen Falls-Mukono North line. For secure operation of the Western wing of the network, we recommend the proposed construction of the 132kV Kapeeka-Kiboga-Mubende-Nkonge line or the proposed 220kV Kafu Kinyara-Hoima line. Also, we recommend that the single circuit lines in the central region should be upgraded to double circuit lines because most of the load is in the central region and is ever-growing. With Karuma HPP, 400kV Karuma-Kawanda link, and the shunt reactor at Opuyo substation all on, the operation of the Northern and Eastern parts of the network is secure and stable. Operating Karuma at full capacity significantly reduces the loading of most lines and helps improve the bus voltages.