This paper presents a new approach to real-time fault detection in power transmission systems using Fuzzy Logic (FL) based transmission line distance protection module. The proposed module uses samples of voltage and current signals to calculate line impedance, which used to construct an input-output data. Simulation studies are preformed and influence of changing system parameters such as fault resistance and fault location. Details of the design procedure and the results of performance studies with the proposed relay are given. Practical computer simulation program for monitoring the input and calculated values is built based on the Matlab 7.4-Real Time Simulink with National Instruments Data Acquisition System type (NI DAQ-6251). The results show that this approach can be used as an effective tool for high speed digital relaying, a correct detection is achieved in less than 10ms, results performance shows that the proposed algorithm is fast and accurate as compared with others used relays.

Application of Fuzzy Logic (FL) theory to self-tuning PID controller for the reactive power compensation using Synchronous Machine (SM) is investigated in this paper. The measured Power Factor (PF) is adjusted to a required value using FGS based PID controller. If the measured PF is different from the required reference value an error signal is generated. This error signal and change of error are evaluated by FLC to obtain the new constants values for the PID controller that used to drive six-pulse full wave thyristorized rectifier circuit, which can thus control the excitation field voltage. A VAR compensation for the weak bus, with a desired PF, has been applied on the modified IEEE-5 bus sample systems using bifurcation analysis and Q-V sensitivity methods as voltage stability indicator. In this paper, a suitable model of the SM has been presented. Loading and no load conditions in addition to excitation field voltage have been tested. A good agreement between practical and theoretical results has been observed. Simulation results demonstrate that better control performance can be achieved in comparison with Ziegler-Nichols controllers and Kitamori's PID controllers. It has been found that the proposed controller (FGS based PID) provides fast response, flexible, nonlinear gain characteristic and adaptive operation. It is concluded that the reactive power compensation system with a FGS based PID controller of SM is reliable, sensitive, economical, faster, and more efficient with no harmonics.