  Security is one of the biggest concern in power system operation. Recently,
the emerging cyber security threats to operational functions of power systems
arouse high public attention, and cybersecurity vulnerability thus become an
emerging topic to evaluate compromised operational performance under cyber
attack. In this paper, vulnerability of cyber security of load frequency
control (LFC) system, which is the key component in energy manage system (EMS),
is assessed by exploiting the system response to attacks on LFC
variables/parameters. Two types of attacks: 1) injection attack and 2) scale
attack are considered for evaluation. Two evaluation criteria reflecting the
damage on system stability and power generation are used to quantify system
loss under cyber attacks. Through a sensitivity-based method and attack tree
models, the vulnerability of different LFC components is ranked. In addition, a
post-intrusion cyber attack detection scheme is proposed. Classification-based
schemes using typical classification algorithms are studied and compared to
identify different attack scenarios.
