The Apparent Power of Electric Circuits With Switching Elements in Single-Phase Systems

摘要

This paper presents calculation of the apparent power of electric circuits with switching elements and various loads in single-phase systems. Attention is paid to the difference between such fundamental concepts as "the electromotive force (EMF) of a voltage source" and "the input voltage of an electric circuit" causing the electric current to flow. On that ground, an analysis of apparent power components with pure resistance and pure inductance is made. The periodical functions of voltages u(t) and currents i(t) are presented in the shape of orthogonal base functions. It is demonstrated that the switching elements cannot cause appearance of reactive power. It is shown that the power balance of the feeding source and the load for the given examples is always correct. The calculated power values are being compared to those obtained based on the IEEE Standard 1459-2000 and the Currents' Physical Components Power Theory (CPC PT). The calculations of the exchange power Q{sub}(ex) are presented.