Dynamically Corrected Fast Estimators of Active and Reactive Power and Their Performance

Development of several fast estimators of active and reactive power is presented. The estimators are considered from the point of view of the fast measurement of criteria values in power system automation devices. The main idea of the method is dynamical correction of transients realized thanks to recognition of fault instant and taking into consideration of post fault samples only. In the case of reactive power it is possible to get unique transient response and to realize dynamical correction. Increasing filter window starting from fault instant allows to get better accuracy of estimation in presence of noise. Having small noise it is possible to estimate the reactive power starting from one sample and the active power from two samples of increasing data window. The functions of dynamical correction can be calculated analytically or by using a digital simulation.