Static Security Assessment of the Kenyan Power System Using Contingency Analysis

Abstract

Static Security Assessment of the Kenyan Power System using contingency analysis. The demand for reliable power supply in Kenya has been driven by increased industrialization however, the reliability of the Kenyan Power System recently came into question following frequent blackouts affecting the entire country almost yearly for the past three years. In June 2016, a fault at Gitaru Power Station led to the loss of 180MW which triggered a national blackout that lasted for over ten hours. As recently as 8th January 2017, the Nairobi, Coast and Mt. Kenya regions were plunged into darkness due to a technical fault at the Nairobi North Substation that cut the supply off to Nairobi from Olkaria geothermal fields. Following these rampant outages, there is need to study the security of the system. This project aimed at evaluating the static security of the Kenyan Power System using Contingency analysis and offer recommendations to mitigate the vulnerabilities of the power system. To achieve this, the Kenyan Power System was modelled, and a contingency analysis done for different operating scenarios factoring in generators and transmission lines and considering an outage level of (N-1) using DIgSILENT Power Factory software. AC Load Flow method Newton-Raphson was used to perform the CA since it was able to give information on the reactive energy flows and the bus voltages in the system. The component loading was between 80 -90 percent which operated closer to their loading limit thus limiting the load expansion and ability to withstand loading in case of a contingency. The bus voltages before CA was done ranged from 0.99 p.u. to 1.02 p.u and a loss of transmission line caused them to drop to as low as 0.6 p.u due to a decrease of reactive power injection. There is need to strengthen their loadability through redundancy of the system components. Recommendations to correct these violations without load shedding have been suggested to enable the system handle an outage level of (N-1). Key Words: Power System Security, Load flow, (N-1) Security, Contingency analysis, load shedding