Page 525 - Decision Making Applications in Modern Power Systems

484 Decision Making Applications in Modern Power Systems

design a reliable decision-making algorithm, total 15 features are selected
which are very distinctive to discriminate different operating scenarios of the
power system network such as no-fault, fault, PS, and fault during PS condi-
tions. The distinct features that have been considered to design input datasets
to the WPE_BDT modules are calculated using Eqs. (18.1) (18.6) and given
hereunder:

S1 5 Rate of change of frequency at the sending-end bus (Δf)
S2 5 Rate of change of load angle at the sending-end bus (Δδ)
S3 5 Rate of change of voltage at the sending-end bus (ΔV)
S4 5 Rate of change of active power at relaying point (ΔP)
S5 5 Rate of change of reactive power at relaying point (ΔQ)
S6 5 SD of wavelet packet energy of Ia1
S7 5 SD of WPE of Ib1
S8 5 SD of WPE of Ic1
S9 5 SD of WPE of va1
S10 5 SD of WPE of vb1
S11 5 SD of WPE of vc1
S12 5 SD of WPE of Ig1
S13 5 SD of WPE of Ia2
S14 5 SD of WPE of Ib2
S15 5 SD of WPE of Ic2

Δf s 5 f s iðÞ 2 f s i 2 kð Þ ð18:1Þ

ΔV s 5 V s iðÞ 2 V s i 2 kð Þ ð18:2Þ

Δδ s 5 δ s iðÞ 2 δ s i 2 kð Þ ð18:3Þ

ΔP s 5 P s iðÞ 2 P s i 2 kð Þ ð18:4Þ

ΔQ s 5 Q s iðÞ 2 Q s i 2 kð Þ ð18:5Þ

8 v ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi9
u N21
< =
u 1 X 2
σ s 5 t ð x i 2μÞ ð18:6Þ
ð N 2 1Þ
i50
: ;
where i is the current sample count, k is the number of samples/cycle, N is
the total number of samples, μ is the mean of samples, σ is the SD, x is the
current sample, f is the operating frequency, V is the operating voltage at
the sending-end bus, δ is the power flow angle at the sending-end bus, P is
the active power, Q is the reactive power.
The flowchart of the proposed protection scheme has been described in
Fig. 18.6, which constitutes six stages and four different WPE_BDT mod-
ules. Different stages of proposed reliable decision-making algorithm has