Constraints of instantaneous reactive power p − q theory

Abstract

The instantaneous reactive power (IRP) p-q theory can be acknowledged as the first concept that provided fundamentals for switching compensator control and very often such a control is satisfactory. There are situations when this control can result in objectionable effects, however. Instantaneous active and reactive powers, p and q, defined in the IRP p−q theory, were introduced with the emphasis that the definitions of these powers are valid for any three-phase system, without any constraints as to the system properties with respect to the load structure and the supply voltages and load currents waveform. This may imply a conclusion that the instantaneous powers p and q specify the power properties of the threephase systems regardless of such systems properties. This assurance regarding the lack of constraints has contributed to the dissemination of the IRP p−q theory, especially as a fundamental of the algorithms for switching compensator control. This study shows that such a conclusion has no ground, however. In fact, only at very specific properties of the three-phase system some conclusions on its power properties can be derived from the values of the instantaneous active and reactive powers. Also, it shows that the IRP p−q theory identifies the power properties of the three-phase loads correctly only on the condition that such loads are supplied with symmetrical and sinusoidal voltage.

Experimental Evaluation of a CPT-Based Four-Leg Active Power Compensator for Distributed Generation

“…This filter has been designed with a relatively high cut-off frequency to avoid jeopardising the overall dynamic response. Notice that the application of filters is also necessary to implement APFs based on other power theories, for instance p-q power theory [19,31].…”

“…The performance of the APF is heavily dependent on the control system applied which is usually based on a power theory, with many applications using the p-q or modified p-q power theories. However, one of the reported disadvantages of these methodologies is their sensitivity to distortion in the signals and the generation of unwanted current components in some operating conditions [19] [20].…”

Comparative analysis of reactive power definitions in the presence of harmonics

“…Ovakvo fizičko objašenjenje trenutne reaktivne snage je izazvalo različite reakcije [19], [21], [22]. Ono što se ne može osporiti je njihov značaj kao algoritama za upravljanje aktivnim filtrima i kao važan doprinos ovih teorija ističe se zaključak da se ovako definisana reaktivna snaga teorijski može kompenzovati bez upotrebe elemenata za skladištenja električne energije (prigušnica i kondenzatora).…”

Exploring sensitivity of mathematical model for the system of voltage symmetrization

“…Ref. [3,4] consider mathematical models of voltage and current symmetrization systems based on the p-q theory. Ref.…”