Effect of Supply Voltage Harmonics on IRP-Based Switching Compensator Control

The instantaneous reactive power (IRP) p-q theory is one of the major theoretical tools for the development of algorithms for generating reference signals for control of switching compensators, commonly known as active harmonic or power filters. This paper presents results of study on how the supply voltage harmonics affect the reference signal that is generated using the IRP approach. According to this approach, the compensator should also compensate, apart from the IRP, the alternating component of the instantaneous active power of the load. The paper, however, demonstrates that in the presence of the supply voltage harmonics, an ideal, unity-power-factor load has an instantaneous active power with a nonzero alternating component. According to the IRP-based approach, it should be compensated, and this requires that a distorted current be injected into the distribution system. Thus, the conclusion of the IRP p-q theory that the instantaneous active power of ideally compensated loads should be constant is generally not true. The currents' physical components (CPC) power theory is the main theoretical tool for the presented analysis.