2D Power Quality Disturbances Detection And Compression Based On Wavelet And Ridgelet

Detection and compression of power quality disturbances in power system are new research topics, which become more and more important with the development of power information system,extension of power grid and improvement of power quality. The modern industry, commerce and residents have put forward higher requirements to the power quality. Harmonic analysis as a main method of power system has been paid more and more attention, in which non-stationary harmonic analysis is an important and difficult problem. On the other hand, with the constantly improvement of power system real time monitoring, it's very important and urgent to be solved of large quantity of measured datum's storage and transmission in power system, and the key way to this problem is using data compression.The concept, causation and hazard of harmonic were introduced in this paper and then the analysis methods of stationary harmonic in power system were summarized. View to the current traditional stationary harmonic analysis methods are difficult to detect the characteristics of non-stationary harmonic accurately, a new method based on time-frequency energy group was proposed, and 3D time-frequency energy group didtribution graphes of non-stationary harmonic were also given, which were used to describe the signal character as a new method. By simulation, the result of using this method is better than using Fourier analysis which can not resolve the problem.Besides, The generation, research state, basic theory and implemention method of ridgelet were researched. Ridgelet is a new multiscale analysis tool, which was applied in images denoising and compression that have clear line singularity. By comparing the result with that of using the same method based on wavelet, we can conclude that the algorithm in this paper can get better performance. So, if power qulity disturbance has such character in 2D space, it will be more suitable to use ridgelet to compress the signal effectively.Power quality disturbance signal compression algorithm based on 2D ridgelet and wavelet was also deeply researched and simulated. Firstly, disturbance was mapped from 1-D to 2-D, then compressed it by an improved compression algorithm based on ridgelet and wavelet. By comparing a series of compression performance indexes with those of only using ridgelet or wavelet, it is shown that the improved algorithm has a higher SNR and lower MSE when compression ratio is very low.The crucial technologies of power data transmission system based on GPRS were also discussed in this paper. The compressed data transmission of the monitoring system master station was designed and realized. On the basis of selection of socket, transmission mode and protocol, the programs of data compression, decompression based on ridgelet transform and GPRS data transmission were completed. At last, mass of experiments confirmed the reliability and stability of the transmission programs.