Ali M. Yousef

Efficient fuzzy logic load-frequency controller

Abstract This paper investigates an application of the fuzzy logic technique for designing the load–frequency control system to damp the frequency and tie line power oscillations due to different load disturbances. The proposed fuzzy load–frequency controller, called a two layered fuzzy controller, consists of two layers. The first one is called the precompensator, which is used to generate and update the reference value of area control error (ACE), while the second one, called feedback fuzzy logic controller, makes the ACE decay to zero at steady state. The simulated power system consists of an integral control, two area load–frequency power system. The proposed two layered fuzzy logic controllers are designed for each area. The studied power system is subjected to a wide range of load disturbances to validate the effectiveness of the proposed controller. Moreover, a comparison between the power system frequency error responses using the conventional integral control system only and the proposed fuzzy controller is reported and obtained. The digital results prove the power of the present two layered fuzzy load–frequency controller over the conventional one in terms of fast response with less overshoot and small settling time.

Optimal pole shifting for power system stabilization

Abstract A method for shifting the real parts of the complex open-loop poles to any desired positions while preserving the imaginary parts is presented. In each step of this approach, it is required to solve a first-order or a second-order linear matrix Lyapunov equation for shifting one real pole or two complex poles, respectively. This presented method yields a solution, which is optimal with respect to a quadratic performance index. The attractive feature of this method is that it enables solutions to complex problem to be easily found without solving any non-linear algebraic Riccati equation. The gain feedback is calculated one time only and it works over wide range of operating conditions. The digital computation results verify the effectiveness of the proposed PSS for less overshoot and less settling time compared with the open-loop techniques. Moreover, the damping and synchronizing torques of the synchronous machine with and without the proposed robust PSS are calculated.

Effect of non-linearities in fuzzy approach for control a two -area interconnected power system

This paper describes the application of the fuzzy logic controller method on load frequency power systems. Integral and PID controllers are designed and compared with fuzzy logic controller. The controller employ local feedback signal from the output to the input. To validate the effectiveness of the proposed controller, a single-area and two-area power system are simulated over a wide range of operating conditions and system parameters change. Moreover, system non-linearity such as Generation Rate Constraint (GRC) and governor dead band have been included in the simulation studies. Further, comparative studies between the conventional integral control, PID control and proposed efficient fuzzy logic load frequency control are included on the simulation results. To analyze the time response of area frequency deviations and net interchange deviation following a small load change in one of the areas in an inter connected two-area power system under different control modes, to study the effect of changes in controller parameters on the response and to select the optimal set of parameters for the controller to obtain the best response under different operating conditions.

Improvement of synchronizing and damping torque coefficients based LQR power system stabilizer

Design of power system stabilizer for enhancement power system stability is proposed. Formula for the effect of the proposed PSS on the synchronizing and damping torque coefficients is obtained .To study the power and effectiveness of the proposed linear quadratic regulator (LQR) power system stabilizer , a sample power system in a linearized model is simulated and subjected to different operating conditions. The power system dynamic responses after applying a variety of operating points with the proposed PSS stabilizer are plotted. Further, the effect of connecting the proposed power system stabilizer on synchronizing and damping torque coefficients is tabulated . A comparison between the effect of the power system stabilizer based on either pole assignment approach, the proposed LQR stabilizer in terms of either power system responses or its I the optimal performance . Alternative adaptive control techniques have been proposed to overcome such problems [7-101 . However, most adaptive controllers are designed on the basis of a linear model and parameter identification of the system model in realtime which is a time consuming task. The present paper uses LQR control approach to design a power system stabilizer[9]. An expression for synchronizing and damping torque coeficients with robust controller is established.

Stand Alone Wind Energy Conversion System Based on Functional Predictive Control

This paper investigates the application of the model predictive control (MPC) approach to control the voltage and frequency of a stand alone wind generation system. This scheme consists of a wind turbine which drives an induction generator feeding an isolated load. A static Var compensator (SVC) is connected at the induction generator terminals to regulate the load voltage. The rotor speed, and thereby the load frequency are controlled via adjusting the mechanical power input using the blade pitch-angle control. The MPC is used to calculate the optimal control actions including system constraints. To alleviate computational effort and to reduce numerical problems, particularly in large prediction horizon, an exponentially weighted functional model predictive control (FMPC) is employed. Digital simulations have been carried out in order to validate the effectiveness of the proposed scheme. The proposed controller has been tested through step changes in the wind speed and the load impedance. Simulation resu...

Fuzzy FACTS voltage regulator for isolated wind energy conversion systems under different wind speed and loading conditions

The present paper aims to design a fuzzy FACTS controller called STATCOM for voltage regulation of Standalone wind energy conversion systems. The Wind energy conversion system consists of wind turbine drives a permanent magnet synchronous generator PMSG feeding static or dynamic loads. The FACTS Statcom controller is adapted and controlled using Fuzzy Logic approach. The Loading types of Wind Energy Conversion are static and dynamic loads. The Dynamic load is pumping systems for irrigation applications. The model of turbine system, PMSG, Transmission system, Loads, Statcom controllers, and Fuzzy logic control system are modelled. The studied system is simulated using Simulink Matlab software package. The Simulated system is subjected to a varieties of disturbances such as load variations and wind speed variations. The digital simulation results prove the effectiveness and powerful of the suggested Fuzzy logic controllers in terms of Fast voltage regulation.