Instantaneous Reactive Power Theory: A Reference in the Nonlinear Loads Compensation

The instantaneous reactive power theory was published 25 years ago, in an IEEE Transactions. Since then, it has been the most used in nonlinear load compensation with active power filters. Its application allows constant source power to be obtained after compensation in a simple way. Moreover, some researches have showed up some limitations of the theory, i.e., it goes optimally with source voltage balanced and sinusoidal, but not so good with source voltage unbalanced and/or nonsinusoidal, since the source current obtained is not balanced and sinusoidal. This paper presents a new compensation strategy in phase coordinates, equivalent to the original theory's one. Its simplicity, due to the nonnecessity of coordinate mathematical transformation, makes easier the modifications necessary to obtain alternative compensation objectives. In this way, this paper presents those modifications and derives compensation strategies that obtain alternative compensation objectives: unity power factor or balanced and sinusoidal source current. Finally, compensation strategies are applied to a practical power system, and the results are presented.

I. Introduction

The instantaneous reactive power theory was initially published in English in the Proceedings of the International Power Electronics Conference in 1983 [1]. However, it was in 1984, after its publication in an IEEE Transactions, when this theory became well known worldwide [2]. Since then, the instantaneous reactive power theory has been the most used compensation strategy in active power filters (APFs). Indeed, the strategy proposed obtains sinusoidal and balanced currents, constant instantaneous power, and unity power factor in the source side when the voltage applied is balanced and sinusoidal [2]. In any other case, i.e., when the voltage is unbalanced and/or nonsinusoidal, the instantaneous power is constant after compensation in the source side, but the current is not balanced and sinusoidal, and the power factor is not the unity [3], [4].