Generalized Theory of Instantaneous Reactive Quantity for Multiphase Power System

A new generalized definition of instantaneous reactive quantity in the multiphase system is proposed in this paper, and an attempt is made to seek its unity in value as well as in meaning between in sinusoidal and in nonsinusoidal situations. By directly taking the instantaneous multiphase voltage and multiphase current as two vectors with multicomponents each, the instantaneous reactive quantity is considered as the second asymmetrical tensor resulting from the outer-product operation of voltage and current vectors. In this way, the so-called zero-phase sequence component problem is solved.With its concise and direct expression, the theory can be applied to any kind of three-phase systems, and can also be easily extended to any n-phase systems without any additional transformation, in which the instantaneous quantities will have similar properties to those in a steady sinusoidal three-phase system. Therefore, it may find wide application in many fields.