Research On Natural Frequency Rapid Extraction And Application

EHV(Extra High Voltage) transmission line is long, its distributed capacitance is bigger, therefore the natural frequency and the transient component will impact the performance of protection. The contradiction between the reliability and rapidity of the traditional protection has arisen. Protection criterion and phase-selection criterion can lay protective relay for EHV transmission line, so it is crucial to get the natural frequency quickly. The main contents are as follows.Firstly, the character of natural frequency is analyzed, in order to get them the method of ESPRIT Algorithm base on Spatial Spectrum Analysis is proposed, comparing four frequency estimation methods which is widely used. Verify the accuracy and rapidity of ESPRIT Algorithm, that can estimate the natural frequency effectively.Power system transient process is simulated by RTDS, measure the data signal through ESPRIT Algorithm and observe the character. The impact factors of algorithm are discussed, including SNR, the number of array, the number of snap. It is necessary to choose a appropriate array and snap number for the natural frequency.Finally, protection criterion and phase-selection criterion is introduced base on natural frequency, the key problem is studied, solutions are proposed to aim at criterion field application.