DYNAMICALLY CORRECTED FAST ESTIMATORS OF CURRENT AND VOLTAGE MAGNITUDE

Fast digital estimation of current and voltage magnitude for power sys tem protection purposes is considered. The magnitude estimators applie d nowadays very frequently employ sine/cosine nonrecursive filters, an d their response time is determined by the filter data window, which i s usually not shorter than one period of the fundamental frequency. Th e response time of such estimators can be significantly reduced (in th e fastest variant up to two sampling periods) by use of a new dynamic correction method which is presented in the paper. It is shown that ap plication of the method to the estimator design simplifies the estimat or structure, since the orthogonal filters are not necessary for magni tude calculations. Thus the computational burden in real-time implemen tations can be reduced remarkably and the optimisation of the filtrati on process can be carried out. Results of simulation tests of the prop osed method are also included.