European Journal of Scientific Research - EuroJournals

932 Samuel N. Ndubisi and Marcel .U. Agu
B. A Three phase fault was applied after 2 seconds and cleared in 4 seconds in fig 4 and
the response of the FAVR is recorded below.
Figure 10: (a) Step response of FAVR to three phase fault.
(b) Fuzzy input voltage to the generator
5. Conclusion
A proportional integral (PI) type fuzzy regulator for terminal voltage and reactive power control of
turbo generators is considered in this work. The result shows that the FAVR performance is very high
as compared to convectional AVR. The overshoot, settling time and rise time are highly reduced
during the two tests conducted. The observed set back is on the steady state error which can be cleared
by automatically tuning the gains g0, g1 and g2 to achieve the required result.
6. List of Symbols and Abbreviations
Symbols
δ () t power angle of the generator, radian.
ω () t rotor speed of the generator, radian/s
P mechanical power, p.u.
m
() t
P e active electrical power delivered by the generator, p.u.
E′ q () t transient EMF in the quadratic axis in the generator, p.u.
E f () t equivalent EMF in the excitation coil, p.u.
Vt () t generator terminal voltage, p.u.
V s infinite bus voltage, p.u.
U f output of the PI fuzzy controller.
H inertia constant
V error voltage
e
V setpoint or reference voltage
d
V exciter output voltage
f
K E exciter gain
K generator model gain
G
τ E exciter time constant
τ generator time constant
G
g , g , g fuzzy gains
1
2
0