Frequency Relays

This project monitors the frequency fluctuations in power system and detects them. therefore we have designed a microcontroller based underover frequency relay. the under-frequency relay is used for automatic load shedding and restoration. the frequency of the system is continuously monitored by using digital monitoring and data acquisition system. the monitored frequency is displayed and depending on the value of the frequency, the required decision is taken by the microcontroller. this project, hardware as well as software for frequency relaying, has been developed. in this project we have used microcontroller 8051 for detecting the frequency fluctuations. when frequency goes below or above from desired value appropriate trip signal is generated in the form of leds. frequency variation also decreases the life of the equipment and directly affects the overall production of the plant. we can give an overview of the complete operation with the help of microcontroller 8051 kit having internal 8255 programmable peripheral interfaces, a zero cross detector and a smps or switched-mode power supply. a zcd converts the input sinusoidal signal to a square wave of the same frequency