Fuzzy Applications in a Multi-Machine Power System Stabilizer

Abstract

-This paper proposes the use of fuzzy applications to a 4-machine and 10-bus system to check stability in open conditions. Fuzzy controllers and the excitation of a synchronous generator are added. Power system stabilizers (PSSs) are added to the excitation system to enhance damping during low frequency oscillations. A fuzzy logic power system stabilizer (PSS) for stability enhancement of a multi-machine power system is also presented. To attain stability enhancement, speed deviation (Δω) and acceleration (Δϖ) of the Kota Thermal synchronous generator rotor are taken as inputs to the fuzzy logic controller. These variables have significant effects on the damping of generator shaft mechanical oscillations. The stabilizing signals are computed using fuzzy membership functions that are dependent on these variables. The performance of the fuzzy logic PSS is compared with the open power system, after which the simulations are tested under different operating conditions and changes in reference voltage. The simulation results are quite encouraging and satisfactory. Similarly, the system is tested for the different defuzzification methods, and based on the results, the centroid method elicits the best possible system response.

Damping of Oscillations in Smib Using Fuzzy Logic Based PSS

“…Fuzzification interface is the process of mapping inputs to fuzzy sets in the various input universe of discourse the mapped data are converted to linguistic terms [10], [11].…”

“…The data base provides the necessary definitions, which are used to define the linguistic control rules and fuzzy data manipulation in a FLC. The decision making logic has the ability of stimulating human decision making based on fuzzy concept [10], [11].…”

“…The number of linguistic variables specifies the quality of the control which can be achieved using the fuzzy controller. As the number of the linguistic variables increases, the computational time and required memory increases [9], [11].…”

Selection of Membership Functions Based on Fuzzy Rules to Design an Efficient Power System Stabilizer

“…The fuzzy logic control scheme is an alternate to overcome the above-mentioned limitations of CPSS [6]. The fuzzy PSS posses lesser computational time and robustness over different operating points, i.e.…”

“…Thereafter, the most designs were developed by using modern control theory like eigenvalue (pole) assignment, optimal control, self-tuning and adaptive control [5]. The design and selection of the PSS structure is a complex iterative process which is around an operating point resulting to unsatisfactory operation for another/varying operating point [6]. The effective PSS design, to make adaptive for any changes corresponding to the varying operating conditions can be achieved by self-tuning, Lyapunov and adaptive control methods of PSS design.…”