Analysis of instantaneous NSV&C in polyphase systems

Abstract

(N-1)-phase N-wire systems are analyzed into an orthonormal-coordinate system using the fundamental laws of polyphase systems and the condition of zero neutral-current. N-dimension voltage vectors are referenced to a virtual star-point and the current vectors are decomposed into three mutually orthogonal components, two of them are responsible of the active power. Without the condition of zero neutral-current, results are modified: the current vector is decomposed into a power-current vector and a complementary current vector. Only the first component transports the instantaneous collective power, the other is useless. The analysis is valid for a general situation and shows the condition of line losses minimization after compensation with active power filters.