The determination and correction of measurement anomaly based on wavelet-threshold method

The malfunction of measuring apparatus is almost inevitable in electric system and will result in inaccurate settlement amount of electricity sales. The backup measures, such as dual-apparatus, calculations from the measurement on other side of line or Tele Meter Reading of EMS are helpful to rectify the erroneous data. It has to detect the anomaly according to the inherent character of load as those back-up absent. A method of determination and correction of measurement anomaly based wavelet-threshold is proposed in this paper. It decomposes the measurement data in multi-scale space with wavelet transform and determines the scale-coefficient which includes the anomaly data based on the difference between normal load fluctuation and extraordinary error. A modified threshold function is used to separate the error component from the scale-coefficient. The correction component can be reconstructed from the error component in the binary tree of wavelet transform. An example is given to test and verify the method finally.