Assessing the impact of intermittent power generation on Uganda's network.

Abstract

This paper discusses the national drive as well as the drive from the international community to have sustainable energy as a way to achieve the Sustainable Development Goals. Sustainable energy requires that more than one energy source is utilized on the grid and these energy sources have to be renewable. This paper entails how the inclusion of the intermittent renewables impacts Uganda’s grid stability, particularly voltage stability and frequency stability. To study the impact of intermittent generation (solar) on the frequency stability of the network, the swing equation is used. Swing equation is used for modeling the dynamics of the system. It is then built and simulated using MATLAB. To investigate the impact of intermittent generation on the voltage stability, the circuit is modelled using Power World Simulator. Cases are then considered and defined under the contingency scenarios to be considered during the PV analysis. Voltage stability analysis reveals that increasing intermittent penetration on the network lowers its voltage stability. The voltage at all the buses reaches the critical point (knee) of the PV curve faster as the penetration of intermittent power from solar increases thus voltage instability is reached faster. The Frequency stability of the network is equally lowered by increasing the penetration level of intermittent generation. At 30% penetration level of intermittent generation, the frequency of Uganda’s network would become critically unstable. Adding artificial rotational inertia to Uganda’s network is valuable to increasing the frequency stability of the network in the face of increasing penetration of intermittent generation. As the share of intermittent renewables increases on Uganda’s grid, it is recommended that emergency back-up reactive power reserves and automatic fast start – up of back-up generation are employed to ensure the maintenance of the voltage stability of the grid.