A Generalized Instantaneous Nonactive Power Theory for Parallel Nonactive Power Compensation

Although the definitions of active power and nonactive power in a three-phase sinusoidal power system have been accepted as a standard, it has been an issue on how to define instantaneous nonactive power in power systems with non-sinusoidal or even non- periodic voltage and/or current.

This dissertation summarizes these nonactive power theories, and a generalized instantaneous nonactive power theory is presented. By changing the parameters in the instantaneous active current and nonactive current definitions, this theory is valid for power systems with different characteristics. Furthermore, other nonactive power theories can be derived from this generalized theory by changing parameters.

This generalized nonactive power theory is implemented in a shunt nonactive power compensation system. A three-phase four-wire nonactive compensation system configuration is presented, and a control scheme is developed. The compensator provides the nonactive current component, which is determined by the generalized nonactive power theory. Unity power factor, and/or fundamental sinusoidal utility source current can be achieved despite the characteristics of the nonlinear load. Both the simulation and experiment results verify the validity of the theory to different systems and the capability in a shunt nonactive compensation system.