Abstract
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Cascaded on-load tap changers (OLTCs) are widely
used for coarse control of voltages in largely interconnected elec-
tric power systems. There could be interactions between load
dynamics and OLTC control under certain system operating
conditions which may lead to the OLTC limit cycle phenomena,
thereby resulting into long-term voltage oscillations in the system.
In recent years, renewable and nonrenewable local generation
(LG) units have been getting interconnected in modern power
systems. The existence of OLTC limit cycles in the presence of
LG has not been addressed in the literature in greater details. In
this paper, the OLTC limit cycle phenomenon, which can occur
due to interactions among load dynamics, OLTC controls, and LG
operation in electricity networks, has been investigated. Also, a
novel strategy is explored for mitigating the power system oscil-
lations introduced by OLTC limit cycles, especially for a network
embedded with LG. The proposed mitigation strategy including
detailed investigations and analyses has been verified for a two-bus
test system and successfully tested on a multibus system using
MATLAB