ISSUES WITH GRID INTEGRATION OF RENEWABLE ENERGY SOURCES

Abstract

When renewable energy sources are integrated into the existing power system, then they act as a bridge between the electricity demand and supply, in a sustainable and greener way. But this grid integration poses certain challenges for the power system operator. In this work various issues, which are faced,are addressed. A typical IEEE 13 bus is used to simulate the microgrid environment. Among the various protection issues, high impedance fault(HIF) is addressed here. A high impedance fault(HIF) occurs whenever a conductor gets broken and touches ground or when a line comes in contact of a semi- insulating surface. Due to very small fault current, these faults are left undetected by conventional overcurrent relays. In this work, a technique based on Mathematical Morphology is implemented. Another technique based on the variation of 3rd and 5th harmonic current components is implemented. The fault direction is estimated using the fundamental apparent power. An anti-islanding detection technique, which discriminates between islanding and other events such as capacitor switching, load switching, based on positive sequence current and voltage components is proposed in this work. Another protection issue, which is considered here, is protection system blinding and sympathetic tripping. An adaptive protection scheme, based on the determination of optimal relay settings is implemented. A 5-bus system is simulated for this. All simulations are carried out in real time(RSCAD) using real time digital simula- tor(RTDS).