Power system stabilizer (PSS) is used to damping power system local and interarea modes of oscillation. It will act as additional signal through the generator excitation system which produces a component of electrical torque in phase with speed variation. Fuzzy controller is nonlinear. It is more difficult to set the fuzzy controller gains compared to conventional PID controller. This research proposed velocity (PID-FPSS) its gains are tuned off-line by particle swarm optimization techniques (PSO). The objectives are to damp local-area mode of oscillations that occur following power system disturbances. The effectiveness of the proposed technique is illustrated by applying the velocity PID-FPSS to a single-machine infinite bus power system that is typically used in the literature to test the performance of power system stabilizers. The simulation studies has been tested in MATLAB SIMULINK package . A comparison between the proposed PID-FPSS and a well-tuned and designed robust power system stabilizer (RPSS) confirms the superiority of the PID-FPSS.

The use of proportional integral (PI) load frequency control (LFC) to ensure the stable and reliable operation of electric power system is practical important. Any imbalance between synchronous generators and consumption loads will cause frequency unstable within the complete power system. The purpose of the load frequency control (LFC) is to keep the power system frequency and the inter-area tie power as near equilibrium point. This article introduces a gain schedule PI fuzzy load frequency control (GLFC) applying to two area electric power system. The GLFC consists of two level control systems, where the PI controller in the conventional form and its parameters are tuned in real time by fuzzy system. A fuzzy rule base is constructed in the form set of IF-THEN that describe how to choose the PI parameters under different operating conditions. The simulation has been conducted in MATLAB Simulink package. The effectiveness of the GLFC is measured by comparison with conventional PI load frequency controller.

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The use of power system stabilizers (PSSs) to damp power system swing mode of oscillations is of practical important. The authors purpose is to retune the power system stabilizer (PSS1A) parameters in Unitrol D produced by ABB– was installed in 1995 in Benghazi North Power Plants (BNPPs) at General Electricity Company of Libya (GECOL). Power systems are steadily growing with larger capacity, so the optimal values of the power system stabilizer (PSS1A) parameters should be retuned. A particle swarm optimization technique (PSO) is used to determine the parameters of the PSS off-line. The objective is to damp the local and inter-area modes of oscillations that occur following power system disturbances. The retuned power system stabilizer (PSS1A) can cope with large disturbance at different operating points and has an enhanced power system stability, The MATLAB package with SIMULINK is used for the design and simulations.

This paper introduces adaptive variable structure fuzzy controller as a power system stabilizer (AFPSS) used to damp inter-area modes of oscillation following large disturbances in power systems. In contrast to the conventional PSS, fuzzy-based stabilizers are more efficient because they cope with oscillations at different operating points. The proposed controller is a fuzzy-logic-based PSS that has the capability to tune its rule-base on line. The change in the fuzzy rule base is done using a variable-structure algorithm to achieve optimum performance. The adaptive algorithm of the proposed controller significantly reduces the rule base size due to its adaptively and improves its performance. This statement is confirmed by simulation results of a three-machine infinite-bus system under different operating points.