Study Of Measured Data Compression, Transmission And Decompression On Power System

It's very important and urgent to be solved of large quantity of measured datum's communication and storage in power system with the gradually spread of transformer substation automatization and the key way to this problem is carrying out data compression. To this actuality in our country, this paper has discussed theoretically and made mass simulinks on the related problems to the compression, remote transmission and decompression of measured datum of power system.Firstly, some basic theory such as definition, evaluation standard and etc. on datum compression and datum communication and two private networks of power system are introduced.Secondly, the measured datum of power system are divided into two instances to have a study on compression: normal and fault recording signals, which are recognized by the state of a special relay used to record the state of power system. One is to use Fourier transformation to convert the source signal from time domain to frequency domain and to discard high frequency harmonious components upwards of 19(GB/T14953-93 D5.3 demanding), then to have static Huffman coding to the quantized char array which is composed of reserved direct current component and basic wave and each high frequency 's amplitudes and angles. The other is to use discrete wavelet transformation to convert the source signal from time domain to frequency domain and to set the high frequency coefficients that its absolute value is smaller than the given threshold to zero, then to have dynamic Huffman coding to the quantized char array which is composed of multiple, wavelet's level, datum length, low frequency coefficients and reserved high frequency coefficients. Mass simulinks and analyses under the two circumstances have done to show that data compression ratio is small and the relative error is also small and within the permission of engineering and the compression problem can be solved in theory of measured datum of power system.Lastly, the method of file transmission is told of. Based on client/server mode, TCP/IP network programming for windows are developed to make remote file transmission practicable by way of Internet. Then a client/serverinterface is made to do the experimentation. Masses of experiments have done to show that the file can be transported from the server to the client effectively and reliably. The comparative analysis of transport effectiveness between the source file and the compressed source file is to verify that the data compression is indispensable.Data decompression is to anti-quantize to the received datum and reconstruct the source singal. This section isn't list solely and its principles and flow charts have introduced along with the introduction of data compression's principles and its source programming on anti-quantization and restructure have list in appendix.