Control techniques for active power filters

Abstract

Filters 1 AbstractThere have been many variants of the active power filter proposed and these variations cover both the circuit topology and the control system employed. Some of the control variants reflect different control objectives but there are still many variants within similar objectives. This paper describes and contrasts the available control techniques in a structured way to identify their performance strengths. Objectives are classified by the supply current components to be corrected and by the response required to distorted grid voltage. The various signal transformations are described in terms of their impact on the distortion identification problem. Time-domain, frequency-domain, instantaneous power and impedance synthesis methods are examined. Additional control functions such as DC-bus voltage and current reference following are also discussed. It is found that a key difference between control methods is way in which current distortion is treated in the presence of distorted grid voltage.

A Refined Self-Tuning Filter-Based Instantaneous Power Theory Algorithm for Indirect Current Controlled Three-Level Inverter-Based Shunt Active Power Filters under Non-sinusoidal Source Voltage Conditions

“…Generally, they are obtained by using indirect identification approach [54], where the dc components are first extracted by using a second STF followed by removal of the extracted dc components from the actual load current in α-β frame. This approach can be expressed as follows:…”

DC-Link Capacitor Voltage Regulation for Three-Phase Three-Level Inverter-Based Shunt Active Power Filter with Inverted Error Deviation Control

“…For the purpose of harmonics extraction, both I Ldpacq and I Lqpacq components are required for reference current generation. Generally, the ac components are obtained through indirect identification approach [46] where a tuned numerical low pass filter (LPF) is usually employed to detect the dc component which is then being removed from the actual load current in dq frame [12,31,40]. This approach can be represented as:…”

A new scheme for power factor correction and active filtering for six-pulse converters loads

“…Considering the properties of three-phase systems, the three-phase quantities can be transformed into two-phase quantities in synchronous rotating reference frame (SRRF, or, d − q reference frame) by applying Park's Transformations [24]. Hence two groups of ADALINEs are adopted in the d-axis and q-axis of the synchronous rotating frame to derive the dc components in d − q reference frame, corresponding to the fundamental components of load currents in stationary phase a − b − c frame.…”

“…. ± 6n + 1 (n is integer), corresponding to the 6n th order harmonics in synchronous rotating frame due to one fundamental frequency shift from the stationary phase coordinate to synchronous rotating reference frame, as discussed in Reference [24]. Therefore, for harmonic estimation of threephase rectifier load currents, only the weights for characteristic harmonics (6n th order) are needed to be updated in the synchronous frame ADALINE.…”