Recognition of Islanding Events and Power Quality Disturbances in Hybrid Power System using Signal Processing Techniques

Abstract

Renewable energy (RE) generation levels are increasing in modern power systems at newlinea fast rate due to their advantages of clean and non-exhaustible nature of energy and newlineto meet future energy demand efficiently. It helps in mitigating the problems of high newlinecarbon emission, greenhouse effect, increased cost of oil and natural gases. Hybrid newlinerenewable energy sources (HRES) have emerged as important sources of energy newlinewhich are effective to fulfil the future load demand by overcoming the problem of newlineenvironment pollution. Solar photovoltaic (PV) and wind energy is emerging as most newlineimportant HRES for grid level generation of renewable energy (RE) power. However, newlinethese sources generate power which is volatile and intermittent nature. Hence, RE newlinegeneration creates technical challenges in terms of operation and control due to newlineuncertain and un-predictable nature of generation. These include power quality, newlineislanding, voltage variations, protection and stability issues. Power quality and newlineislanding issues have been considered for investigation in this thesis work. newlineIslanding is an operational scenario where there is a loss of grid and RE newlinegenerators continue to feed power to the local load. This has harmful effects on the newlineRE generators and operating personal. Hence, it is expected that islanding scenario newlineis identified in minimum time and RE generators are disconnected within 2s duration newlineafter island formation. This research work designed an islanding identification newlinescheme (IDS) by designing a current islanding detection indicator (CIDI) that newlinecombines the features computed by processing the current signals, negative sequence newlinecurrent (NSC) and negative sequence voltage (NSV) using the Stockwell (ST) as well newlineas the Hilbert transforms. Information contained by the total harmonic distortions of newlinevoltage (THDv) and current (THDi) is also used while designing the CIDI. Islanding newlineand non-islanding events of category-I and II are identified and discriminated from newlineeach other by comparison of peak magnitude of CIDI with the first threshold value newline