Transient Stability Enhancement by DSSC with
Fuzzy Supplementary Controller
ABSTRACT
The distributed
flexible alternative current transmission system (D-FACTS) is a recently developed
FACTS technology. Distributed Static Series Compensator (DSSC) is one example
of DFACTS devices. DSSC functions in the same way as a Static Synchronous
Series Compensator (SSSC),
but is smaller in size, lower in price, and possesses more capabilities.
Likewise, DSSC lies in transmission lines in a distributed manner. In this
work, we designed a fuzzy logic controller to use the DSSC for enhancing
transient stability in a two-machine, two-area power system. The parameters of the
fuzzy logic controller are varied widely by a suitable choice of membership
function and parameters in the rule base. Simulation results demonstrate the
effectiveness of the fuzzy controller for transient stability enhancement by
DSSC.
KEYWORDS
1.
D-FACTS
2.
Simulation model
3.
DSSC
4.
Transient stability Fuzzy logic controller
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. Simulation model of
two-machine system for transient stability study with DSSC.
Fig. 2. D-FACTS deployed on the
power line.
Fig. 3. Circuit schematic of a
DSSC module.
EXPECTED SIMULATION RESULTS:
Fig. 4. Changing the rotor
angle difference (d_theta1_2) when the DSSCs entered the circuit.
Fig. 5. Changing the rotor
angle difference (d_theta1_2) after the fault with DSSC (without supplementary fuzzy
logic damping controller) and without DSSC.
Fig. 6. Changing
the angular speed of the machines after the fault with DSSC (without
supplementary fuzzy logic damping controller) and without DSSC.
Fig.7. Rotor angle difference
(d_theta1_2) deviation after the fault with FLC and classic controller.
Fig. 8. Machine voltage
variation after the fault with FLC and classic controller.
Fig. 9. Rotor angle difference
(d_theta1_2) deviation after the fault with FLC and classic damping controller and
without damping controller.
Fig. 10. Machine voltage
variation after the fault with FLC and classic damping controller and without
damping controller.
Fig. 11.
Variation
of FLC output signal after the fault.
CONCLUSION:
In
this study, we introduced a graphical-based simulation model of the DSSC. DSSC
was placed in a sample two machine power system to increase transient
stability. Simulation studies presented in the paper showed that when the DSSCs
were out of service, the rotor angle between the machines (d_theta1_2)
increased rapidly and two machines fell out of synchronism after fault
clearing. However, when the DSSCs were in circuit, DSSCs stabilized the system even
without specific controller. Subsequently, an FLC was added to the main control
system of the DSSC in order to improve the transient stability margin of the
system. The simulation results show that specific to this case, DSSC can
stabilize the system under severe fault. Moreover, a comparative study between
the FLC and conventional classic controller shows that the proposed FLC has
better performance and influence in transient stability enhancement and
oscillation damping
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[1]
Yi Guo, David J. Hil and Youyi Wang, “Global Transient Stability and Voltage
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L. Gyugyi, “Dynamic compensation of ac transmission lines by solid-state
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