Reliability Enhancement Using Optimal Sizing and Placement of Distributed Generation (Case study- Debrework feeder)

Abstract

This thesis investigates the challenges of unreliable power supply due to frequent interruptions on the feeder lines of the Bichena substation. It explores distributed generation (DG) as a potential solution to enhance the substation's reliability. The current state of the Bichena Distribution Substation was characterized by a high SAIFI of 364.0334 f/y, SAIDI of 232.657 h/yr and EENS of 2302.898MWhr/yr, and Deberework feeder reliability indices value SAIFI of 402 f/yr, SAIDI of 271.1hr/yr, and EENS 618.5383MWhr/yr. These values significantly exceed the standards set by the Ethiopian Electric Agency (SAIFI = 20 and SAIDI = 25), highlighting a critical reliability issue. This thesis proposes the strategic integration of DG units to bridge this reliability gap. The study focused on the Debrework feeder within the 15 kV systems, analyzing the effectiveness of a photovoltaic (PV) DG system in improving reliability. Factors such as availability, economics, emissions, and suitability for the area motivated the selection of PV technology. The proposed DG system consists of a 444.465 kWh PV generate, 577.8KW inverter, and 1,0380 Ah battery. This system was injected power into the grid during outages, serving as a backup solution. ETAP software was utilized to simulate various DG scenarios and assess their impact on reliability. The optimal placement and size of DG units were determined with the primary objective of maximizing reliability improvement on the Debrework feeder, particularly for sensitive loads. The analysis aims to achieved a significant reduction in SAIFI, SAIDI and EENS on the Debrework feeder, targeting values of 20.798 f/yr,18.0119h/yr, and 22.28MWhr/yr respectively.so, that the Debrework feeder was achieved the EEA standard. Additionally, the overall substation's reliability indices have improved, with SAIFI decreasing to 179.84 f/yr and SAIDI reducing to 91.909 h/yr. Generally, Due to the DG at an optimal feeder. the overall system’s reliability was improved where the values of the SAIFI, SAIDI, and EENS common reliability indices improved by 50.6%, 60.6%, and 51%, respectively. And from the selected Debrework feeder was 94.8%, 93.4%, and 96.4% reliability improvement were achieved.