Quantifying the contribution of distributed energy resources to power system resilience.

Abstract

In 2005, low rainfall levels resulted in a significant deficiency in generation compared to demand. Government policy thus prioritized the development of new plants and the diversification of generation to reduce the country’s dependence on the Nalubaale power station. Since then, several Distributed Energy Resources (DER’s) have been installed on Uganda’s network in a bid to supplement Uganda’s installed generation capacity and also diversify the energy mix. However, they provide another critical benefit when operated in island mode, through reduction of the impact of Low Probability-High Impact (LPHI) fault events that could lead to widespread blackouts. The networks ability to detect, withstand and recover from effects of LPHI events is power system resilience. This research therefore focuses at quantifying the contribution of Distributed Energy Resources to power system resilience as modelled in DigSilent. Three scenarios were considered i.e. (i) Low Probability High Impact (LPHI) on current network with Existing DER’s and no reconfiguration made (Base case), (ii`) LPHI event on Current network with existing DER’s and reconfiguration made (Scenario 1), (iii) LPHI event on current network with both existing and Future DER’s and reconfigurations made (Scenario 2). Results showed that power system resilience improved from the base case by 35.4% and 52.2% in scenario 1 and 2 respectively. Expressing resilience benefits in cost terms showed that $3,223,042.05 and $10,378,544.83 could be additional sales of power in scenario 1 and scenario 2 respectively. Henceforth, exploitation of DGs can improve the resilience of the Uganda power system network to LPHI events through continued power supply during power outages.