Research On Data Compression And Storage Of Continuous Recorder In Power System

Along with the upcoming standards of the continuous record device in power system, the compression of numerous data and storage of continuous recorder will be important technologies. The recorded pattern and data amount will also take great changes. So the data compression and storage of continuous recorded data based on the wavelet analysis theory, combined with Clark transform and Lz77 encoding are studied in this dissertation. This dissertation contains several following parts.The recorded data are decomposed and reconstructed with wavelet Lift algorithm based on Bior4.4. With this method, the computer memory spending is decreased, and the algorithm speed of decomposition and the precision of signal reconstruction are improved. The energy leakage problem is considered into the calculation formula of the decomposition level in this dissertation. A method of calculating the decomposition level according to the sampling frequency is obtaind. The decomposition level from the method ensures top performance without excessive reconstructive error.An adaptive thresholds method combined with fault recognzied by wavelet transform and Clark transform is presented in the dissertation. This proposed method can differentiate the abnormal data from the normal data. It can also improve the compression ratio and preserve useful fault information effectively. After the thresholding, the low frequency data will be encoded with Lz77 algorithm.The compressed data are stored on the disk sectors directly without building any data files after the compression, For the future fault reappearance and the data query, a relevant cfg file which is used to record the relevant compressed data information every time is also created. The method can also avoid the intricate file management style in Windows OS.At last, operating data are produced by transmission line models constructed with Matlab/Simulink. The compression and storage programe are programmed with Matlab and C language. The data of the simulink model and dynamic modal from CEPRI are compressed and stored with the proposed arithmetic. The results suggest that the arithmetic is valid to compres and manage the continuous recorded data of the power system.