An Optimization-Based Algorithm for Shunt Active Filter Under Distorted Supply Voltages

Abstract

In this paper, an optimization-based control algorithm for the compensation of steady-state load under distorted supply voltages is presented. For balanced and sinusoidal supply voltages, load compensation using shunt active filter produces perfect harmonic cancellation (PHC) and unity power factor (UPF) source currents. However, when the supply voltages are distorted, compensation for PHC will not provide UPF, as the harmonics in the supply voltages are not utilized for delivering the average power. In the same way, to achieve UPF source currents, the compensated source currents should have the same harmonics, unbalance, shape, and be in phase with the respective supply voltages, thereby violating the perfect harmonic cancellation objective. Hence, there should be an optimal operation between these two important compensation characteristics. The optimization-based control algorithm presented in this paper gives the best power factor while satisfying the constraints such as total harmonic distortion limits and average power balance of source currents. It is also flexible to adopt different compensation characteristics based upon the supply voltage conditions. MATLAB and its optimization toolbox are used for simulation studies and solving the nonlinear optimization problem, respectively. The algorithm is validated by using a prototype of digital signal processor (TMS320F2812PGFA)-based shunt active power filter. Detailed experimental results are presented.Index Terms-Active power filter (APF), digital signal processor (DSP), load compensation, optimization, perfect harmonic cancellation, unity power factor.

Switching Functions Model of a Three-phase Voltage Source Converter (VSC)

“…Given that the waveforms of Fig. 11 follow the predictions of (15) to (18) and (35), the experimental results validate the theory.…”

“…11(a). From (15) and (16) and Fig. 2, the neutral current i N (t) divides into equal halves upon entering the VSC from the ac-side and flows along the upper dc bus and lower dc bus.…”

Three-Phase Reference Current Generator Employing with Kalman Filter for Shunt Active Power Filter

“…This approach is popular due to its simplicity, reliability, efficiency and low cost [4], but at the expense of providing incomplete solutions particularly when compensating random frequency variations in the current, tuning and parallel resonant problems. In recent years, various active power filters (APF) configuration with their respective control strategies have been proposed and have been recognized as a viable solution to the problem created by harmonics [5][6][7]. Amongst the technique that have been developed are the extraction and the estimation approach.…”

“…In this technique, it is assume that the frequency of the grid are constant and its only detect the harmonics in the system. Furthermore, the DC NLL have been used by many researchers to generate the distorted current waveform [5,[27][28][29][30][31]. Generally, the NLL is constructed using combination of resistor, inductor and capacitor (RLC).…”

Active filter solutions in energy systems

“…However, these elements can produce harmonics while turning on and off, depending on the switching frequency, which can cause problems in the associated systems [1]. For example, when a linear ohmic load is used stand-alone, it does not draw reactive power; however, when used together with switching elements such as thyristors or triacs, this load draws reactive power and produces effective harmonics [2,3]. Moreover, the use of such switching elements can have adverse effects; in particular, the resulting current and voltage waveforms are periodic, and the sinusoidal form of mains voltage can be broken down [4].…”