Voltage saturation anti-windup for harmonic controllers in multiple reference frames

Abstract

The output voltage references in grid connected Voltage Source Converters must be limited according to the available dc voltage to avoid over-modulation and windup of the current controllers. This may be especially critical for Active Power Filters (APFs), since uncontrolled over-modulation can cause unintended harmonics in the output voltage and interfere with the harmonic compensation. This paper presents an antiwindup mechanism for harmonic current controllers in Multiple Reference Frames (MFRs), which prevents controller windup. The proposed method extends the harmonic compensation capability by allowing operation of each harmonic controller into the non-linear modulation region. This is achieved by selective conditional integration of the errors in each reference frame. Simulation results are presented to demonstrate the effectiveness of the proposed anti-windup mechanism.

Realizable References Anti-Windup Implementation for Parallel Controllers in Multiple Reference Frames

“…4(e)], despite its simplicity, does not offer good results and it is also disregarded. It is noted that the discarded methods are the most similar to those reported in the literature [15], [16], [11].…”

“…The total controller output is the sum of the individual controller outputs (10). An identical result is obtained by summing the controllers' difference equations in (9), resulting in the expression (11).…”

“…The same idea applies, but the saturated vector is calculated also rejecting the component crossing the hexagon limit. These solutions can be seen as instantaneous versions of those proposed in the literature [11], [15], [16] where the harmonic controllers are dynamically disabled when saturation is detected.…”

“…Again, the need of gain tuning makes the solution inefficient in a general case. A conditional cancelation of the multiple reference frame parallel controller integrators is proposed in [11]. It requires tuning of a voltage threshold to disable the integrators as well as calculation of the control signal derivative to enable and disable the cancelation of the different controllers.…”

Realizable Reference Antiwindup Implementation for Parallel Controller Structures

“…This solution is essentially the same as [10], [11] with a state-space formulation. A conditional cancellation of the multiple reference frame parallel controllers is proposed in [13]. It requires tuning of a voltage threshold to disable the controller integrators as well as the calculation of the control signal derivative to enable and disable the cancellation of the different controllers.…”