Page 515 - Decision Making Applications in Modern Power Systems

A reliable decision-making algorithm Chapter | 18 475

In view of the above, there is a necessity to develop an intelligent
scheme that can provide adaptive protection to prevent the malfunction of
distance relay during PS and fault during PS in a DCTL. The proposed
algorithm helps in minimizing the possibility of hidden failures and bud-
ding cascading events by adopting proper decision-making algorithm,
thereby concerning the sensitivity and security equilibrium of distance
relays at predominant system conditions. The main contribution of the pro-
posed research work is to demonstrate the effectiveness of an intelligent
decision-making algorithm based on wavelet packet energy (WPE) and
bagged DT (BDT) (WPE_BDT) for detection and classification of shunt
faults during PS condition.
In this chapter a double-circuit line of Chhattisgarh state power transmis-
sion system is considered to perform various simulation studies for evalua-
tion of proposed decision-making algorithm based on WPE_BDT for
protection of transmission lines during PS condition. In Section 18.2, dis-
crimination of fault scenario from PS and fault during PS is emphasized. In
Section 18.3, modeling and simulation of Chhattisgarh state power transmis-
sion network is described. In Section 18.4 an application of data preproces-
sing technique such as wavelet packet transform (WPT) and an ensemble
classifier based on BDT is illustrated. Section 18.5 deals with the perfor-
mance assessment of the proposed decision-making algorithm and its valida-
tion on real-time digital simulation (RTDS) simulator. In Section 18.6 the
summarization of final outcomes of proposed decision-making algorithm and
its adaptability and reliability is highlighted. In Section 18.7 a comparative
assessment with existing schemes is reported. Finally, Section 18.8 concludes
the chapter.

18.2 Protection challenges in case of a fault during
power swing

Whenever the power transmission system experiences an abnormal event or
a fault, the system is subjected to severe fluctuations in voltage, current,
power flow, and frequency. These fluctuations are incepted at the generator
rotor angle and start evolving into severe power flow oscillations across the
power system network. The occurrence of PS condition in a power transmis-
sion network should be detected to avoid malfunction of the appropriate pro-
tection scheme. There is a need of an intelligent decision-making algorithm
to discriminate different power system operating conditions such as fault, PS
(stable and unstable), and fault during PS.
During PS condition, the load point impedance trajectory will navigate
toward the operating region of a distance protection scheme. In this condition
the operation of distance protection scheme needs to be blocked using PSB
function to avoid undesirable tripping of distance protection scheme by
improving decision-making capability. As these PSs are phase symmetric,