Voltage Stability Analysis of SPV And WECS Integrated into the Western Grid of Bhutan

Abstract

Global warming has become an increasingly significant concern today because of the excessive emission of greenhouse gases. This concern has arisen interests of researchers and power generating companies to venture into renewables. Among all the renewables, solar and wind are two of the most promising resources today. However, unpredictable nature of solar and wind power still remains a challenge while integrating to the grid. In addition, integration of solar photovoltaic (SPV) system and wind energy conversion system (WECS) introduces instability in the voltage profile. This paper discusses on voltage stability issues of the western grid of Bhutan with integration of renewable energy sources (RESs) as a case study by performing Load flow analysis to examine voltage profile at varying penetration levels. Also, the paper presents an analysis on transformer loading, line loading and grid losses to understand grid’s withstanding capabilities at higher penetration level. The behavior of the grid at every penetration level is observed and the results of voltage stability analysis showed an improved voltage profile of the grid when integrated with solar PV and WECS. However, higher penetration of both solar PV and WECS resulted in violation in bus voltages of the network and overloading of number of transformers and lines above 20% penetration level.