Gaber El-Saady
Assiut University
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Featured researches published by Gaber El-Saady.
Energy Conversion and Management | 2002
M.K. El-Sherbiny; Gaber El-Saady; Ali M. Yousef
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.
Electric Power Systems Research | 2003
M.K. El-Sherbiny; M.M. Hasan; Gaber El-Saady; Ali M. Yousef
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.
Electric Power Systems Research | 1998
Gaber El-Saady; M.Z. El-Sadek; M Abo-El-Saud
Abstract This paper presents a power system Static VAR stabilizer based on the fuzzy adaptive model reference approach. The Static VAR Compensator SVC (thyristor controlled reactor-fixed capacitor (TCRFC) type) is used for voltage regulation and to improve power system stability. The proposed control system consists of a feedback fuzzy controller using the speed state deviation and its derivative as input signals. Moreover, a model reference with a fuzzy adaptive mechanism is built to make the power system speed deviation response follow a certain track. The reference model transfer function of second order is chosen which has desired performance specifications. The input signal to reference model is the speed state deviation response. While the error between model reference output response and the power system speed deviation response is an input signal to fuzzy adaptive mechanism, the other fuzzy adaptive mechanism signal is the derivative of the above mentioned error signal. The control signal to the SVC stabilizer comprises the sum of the feedback fuzzy controller output and the fuzzy adaptive mechanism output signals. The proposed control system is proved by digital simulation power system speed and torque angle states response due to various disturbances. Furthermore, the effect of the additional signal comes from the fuzzy adaptive mechanism for enhancing the power system stability. A comparison between power system response using the proposed SVC stabilizer and without adding the control signal of fuzzy adaptive mechanism is presented. The results show the effectiveness and power of the presented SVC.
Electric Power Systems Research | 2001
Gaber El-Saady
Abstract The present paper aims at utilizing the Static VAR Compensator SVC for simultaneously load balancing and voltage flicker elimination due to arc furnace loads. The SVC of thyristor controlled reactor-fixed capacitor TCR-FC type is considered. The effective susceptance of SVC is controlled and adapted by varying the thyristors firing delay angle. The three-phase imbalanced currents of arc furnace load is balanced by adjusting the effective susceptance of SVC Further, at the same time, the voltage oscillations due to arc furnace load currents are eliminated by updating the thyristor firing delay angle of SVC. An equivalent power system comprises a constant voltage source connected to arc furnace load through transmission system and step down transformer. The proposed SVC is connected at the terminal of the arc furnace load. To validate the effectiveness of the SVC in sense of load current balancing, improvement of power factor, and voltage flicker elimination due to arc furnace load, the above power system is simulated digitally over a wide range of arc resistances. The digital simulation results prove the power of SVC in terms of a constant terminal voltage and three-phase balanced unity power factor line currents with varying arc furnace currents.
Electric Power Systems Research | 1999
Gaber El-Saady
Abstract A variable structure sliding mode control system for controlling a static phase shifter is developed. The static phase shifter aims at introducing voltage phase shift between the terminals of transmission line. The voltage phase shift is controlled by adding to the voltage of one end of transmission line a quadrature voltage component. The thyristor switches is used to regulate that quadrature component, whereupon, the phase shift is changed. A sample power system model used for digital simulation is linearzied to design the variable structure control algorithm. To validate the power and robustness of the proposed controller for enhancing power system stability, the studied power system is subjected to different disturbances such as tie line power, frequency or synchronous machine speed disturbances. The power system dynamic responses for the above disturbances prove the effectiveness and superiority of the variable structure control system in terms of fast damping response with less settling time.
Electric Machines and Power Systems | 1997
M.K. El-Sherbiny; Gaber El-Saady; E.A. Ibrahim; Adel M. Sharaf
Abstract The paper presents an efficient and simple fuzzy logic power system stabilizer (FLPSS) for damping electromechanical modes of oscillations and enhancing power system synchronous stability. The essential feature of the proposed controller is that the pole placement approach is used to assign the open-loop poles at certain specified locations at nominal operating point. Then the fuzzy logic controller is employed to excite the synchronous machine excitation system by an incremental signal for enhancing the power system stability over a wide range of operating condition and exciter gain. The input signals to the FLPSS is the speed deviation and speed deviation change. The simulation results using the proposed controller are carried out on an synchronous machine connected to infinite bus through transmission line.Moreover,a comparison between the conventional fixed-gain PI controller and the proposed FLPSS is presented. The results validate the effectiveness of the proposed FLPSS in terms of less ove...
Electric Power Systems Research | 1996
M.K. El-Sherbiny; Adel M. Sharaf; Gaber El-Saady; E.A. Ibrahim
Abstract A novel fuzzy logic controller (FLC) is developed for damping electromechanical modes of oscillations and enhancing power system synchronous stability. The proposed controller is based on state feedback control system. The input signals to the controller are the weighted sum of the mechanical states and the electrical states weighted sum, while its output signal is added to the conventional fixed-gain PI controller output signal to give the excitation control signal. The simulation results using the proposed controller are carried out on an synchronous machine infinite bus system. Moreover, a comparison between the conventional fixed-gain PI controller and the proposed FLC is presented. The results validate the effectiveness of the proposed FLC in terms of less overshoot/undershoot and enhancing the power system stability over a wide range variation of operating conditions.
Electric Power Systems Research | 1996
M.K. El-Sherbiny; Gaber El-Saady; E.A. Ibrahim
Abstract The paper presents an online adaptive artificial neural network (ANN) based power system stabilizer (PSS). The proposed controller is first trained offline using a pole placement based state feedback gain technique at different operating points. The trained ANN parameters (weights and biases) are updated and tuned online using the speed deviation as the reinforcement signal. The proposed PSS is tested at different operating conditions and a variety of regulator gains. The digital results validate the effectiveness and reliability of the new PSS in terms of fast system response under different loading conditions compared with the conventional PI controller and the modern control theory approach of pole placement.
international middle east power systems conference | 2016
Gaber El-Saady; El-Nobi A. Ibrahim; M. Abuelhamd
This paper aims to design a hybrid PD-Fuzzy position controller for high performance linear switched reluctance motor (LSRM). The mathematical model of LSRM is developed and simulated by Matlab/Simulink package. The essential feature of the proposed hybrid PD-Fuzzy controller is to use a PD controller only for coarse position error, then for fine position error LSRM position control is done using a fuzzy logic controller only. New force distribution function (FDF) is proposed to overcome the problems of electromagnetic force ripples due to LSRM nonlinear magnetic characteristics. Through a hysteresis controller, asymmetric three phase power converters can be controlled to drive the LSRM. Simulation results prove the effectiveness of the proposed hybrid PD-Fuzzy controller in position setpoint precise tracking under different loading disturbances and different position setpoint.
international conference on electrical electronic and computer engineering | 2004
Ashraf M. Hemeida; Gaber El-Saady
The damping of electromechanical modes of oscillation in power systems can be made by static VAR compensator (SVC) and/or power system stabilizer (PSS). The paper presents a combinations of using an SVC, controlled by a nonlinear dynamic controller based adaptive neural network, with a PSS, controlled by variable structure fuzzy logic control. The proposed system is used for both damping low frequency modes of oscillation of the power systems, and enhancing the system dynamic performance at post-fault conditions. The proposed variable structure fuzzy logic controller implements the signals of speed deviation and its rate of change, and internal machine angle deviation and its rate of change. The nonlinear dynamic controller based adaptive neural network implements the speed deviation signal. The proposed scheme is validated using a sample single machine connected to an infinite bus power system through a double transmission line circuit. The studied system is modeled and represented by nonlinear differential equations. Matlab software is used for solving the system equations. The time simulation indicates the superiority of using both SVC and PSS over using either of them alone in the studied power system. The results show that using the FACTS combinations provides very fast damping, with less overshoot, and reduces the amount of reactive compensation required for the SVC, and reduces the exciter gain.