Stationary frame harmonic reference generation for active filter systems

Harmonic reference generators for active power filter systems are commonly implemented in the synchronous reference frame, so that simple low or high pass filter functions can be used depending on the requirements of a particular application. High pass filters in particular are used when the reference generator is required to produce an "everything but the fundamental" target waveform. This paper presents a stationary frame notch filter equivalent to a high pass synchronous frame harmonic reference generator for such systems. The use of the stationary frame allows for quicker calculation of the reference generation in a discrete digital implementation, and also allows classical control techniques to be used to analyze the active filter system without requiring synchronous frame transformations of the outside system model. Both simulation (continuous and discrete) and experimental results showing the equivalency of the stationary and synchronous frame reference generation process are presented using both shift and delta operator based IIR digital filters.