A DIGITAL TECHNIQUE FOR ESTIMATING THE FREQUENCY OF A POWER SYSTEM VOLTAGE

Power system measurements and protection are important elements of systems. Recent development of the microprocessor technology has resulted in the use of computer relaying in the power system. Considerable attention is attracted on the implementation of the digital relay during the past seventeen years. An important part of a computer relaying is its algorithms which estimate parameters of the power system. Greatly improved capabilities of microprocessors available on the market have prompted the investigation of powerful algorithms for digital relays. This thesis is concerned with the investigation of new algorithms to estimate frequency from voltage samples. Phase angles of the input signal are calculated using a combined data window approach. Then frequency is estimated by the least squares technique based on the measured phase angles. A feedback technique is used to track frequency changing. The major consideration in designing the algorithms is the rejection of effects of noise from the voltage waveform. The performance of the techniques is examined using simulated data generated on a main frame computer and data recorded in the laboratory. Some test results are also included in the thesis