P-Q instantaneous power theory – a correct theory or useful algorithm for switched compensator control
In this presentation methods useful for determining instantaneous power in the three-phase circuits with periodic nonsinusoidal waveforms have been presented. It may be applied to control shunt active power filter working in real-time. Shunt active filtering is an effective method to eliminate current harmonics. The theoretical considerations have been illustrated by a simulation example carried out for many various operating conditions.
A large class of time-varying filters can be described via pseudo-differential operators belonging to the Hormander class OPS 0 0 , 0. The questions whether and how an input signal can be reconstructed from a known output lead to the problems of invertibility of pseudo-differential operators in that class and of (at least, numerical) solution of pseudo-differential equations. We are going to derive effective conditions for the invertibility for pseudo-differential operators with globally slowly varying symbols as well as for causal pseudo-differential operators, and we study the stability of the finite sections method with respect to time and frequency for these operators.