08-16-2017, 09:25 PM
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fuzzy logic
INTRODUCTION
Condition monitoring of induction motors is a fast emerging technology for online detection of incipient faults. It avoids unexpected failure of a critical system. Approximately 30 40% of faults of induction motors are stator faults. This project uses fuzzy logic to diagnose various stator faults. A fuzzy logic approach may help to diagnose induction motor faults. In fact, fuzzy logic is remembers of human thinking processes and natural language enabling decisions to be made based on vague information. Therefore, this project applies fuzzy logic to induction motors fault detection and diagnosis. The motor condition is described using linguistic variables. Fuzzy subsets and the corresponding membership functions describe stator current amplitudes. A knowledge base, comprising rule and databases, is built to support the fuzzy inference. The induction motor condition is diagnosed using a compositional rule of fuzzy inference.
1.1 PRESENT SCENARIO
Induction motor, which is the important workhorse of all industries. Now days this machines are protected by oldest method that is protection is done by relay and circuit breakers. This type implemented in both static and electromagnetic type. These types of protection are done for protecting the machine for over current and over voltage .the main disadvantage is accuracy and reliability. It would sense the fault after few mille seconds; at that short period there is chance for damage in winding and other motor parts. Therefore there is need for accuracy and reliability of operation; therefore it is necessary for implementing new technique in order to protecting the machine due to high cost. There fore we go for the new method for diagnosing the fault occur in the induction motor. Fuzzy logic based fault identification system is one of recent technique with high accuracy and able to identify fault before it would damage the motor.
PROJECT DESCRIPTION:
The various fault that incurred in the three phase induction motor are identified and diagnose in the initial stage itself .due to involvement of fuzzy logic concept, the accuracy of fault detection get increased. The various fault that are occurred in the three-phase induction motor are unbalanced voltage, single phasing, blocked rotor, overload, over voltage, under voltage. The fault, which is above described, would damage the motor, which would occur in short period. Therefore fuzzy logic based algorithm are used to detect the fault and it is done with the help of micro controller PIC 16f877a.
The motor characteristics during several fault conditions are predicted using mat lab and the simulation result are shown below. The supply before fed to the three-phase induction motor is initially checked by the relay, which is micro controller fed relay. If there is no problem occurred in the supply it will fed to the motor.
The basic block diagram for this analysis is shown above. The supply initially fed to the motor is measured by the measuring circuit .The measuring circuit consist of the current transformer and potential transformer and the regulating circuit. From the regulating circuit it is connected to the micro controller the micro controller check the condition of the supply if there is any fault occurs it will give signal to the relay. Then the relay will automatically cut down the supply. The micro controller that has been incorporate here is the PIC 16f877a.
The Sensing Circuit Which Consist of CT&PT, measuring circuit and regulating circuit. Which initially senses and regulate the supply voltage and current and it give necessary input to the micro controller circuit .The micro controller execute the fuzzy logic algorithm based program which is to detect the various fault that has going to be occurred and it will sense, it will give necessary input to the LCD and relay circuit.
The fault which going to be occurred is initially detected and the corresponding fault are displayed in the LCD display, which is connected to the controller. Therefore this method of fault diagnosis is accurate way of control compare to the Past method and would avoid the damage of the motor