Research On Modern Power Quality Problem And The Development Of Monitoring System

To guarantee the quality of electricity, this thesis investigated on the inhibition of various of steady-state and transient-state with the characteristics of frequency and voltage fluctuation happened during the power transmission, and establishing the observation system.Power quality monitoring system based on Virtual Instrument technology were established to ensure the normal stability of mormal power system and could supervise the remote substation power quality. The site monitoring system was designed to fulfill the achievement of observation and preservation of the waveform signal, power quality parameter measurement, transient signal simulation and harmonic analysis, and the displaying data playback feature. The functions of grid monitoring centre mainly include analyzing the transient signal, monitoring signal waveform and alarming. The modular design and state machine design pattern were conducive to the expansion of system's functions. The system design and the overall function satisfied the remote intelligent monitoring network and were fitted for the layout at the digital substations, with a strong practical value.In addition, a new disturbance detection, identification and location method based on the Adaptive Optimal Kernel Time-frequency Representation (AOK-TFR) was designed in view of the analysis of transient signal. A mutation monitoring method based on cumulative sum algorithm was proposed for low-frequency oscillation to improve time positioning accuracy. The simulation experiments above were carried out for the transient-state, using the method mentioned, which proved that this method could detect, identify and locate disturbances rapidly and accurately to provide a new solution for detecting power disturbance signals.