Active Power Filtering Using the ZDPC Method under Unbalanced and Distorted Grid Voltage Conditions

Abstract

Abstract:In this paper, we propose a new Zero Direct Power Control (ZDPC) technique for active compensation of harmonics and reactive power, using shunt active power filter (SAPF), based on cancellation of instantaneous active and reactive power disturbances by comparison with their zero references. To separate harmonic and fundamental components of the line voltage and current a highly selective filter (HSF) has been used. Depending on the power errors and line voltage vector position, a switching table produces the appropriate control vectors leading to the active and reactive power variation required to reach the zero power references, even under grid voltage unbalanced and distorted conditions. The experimental validation of the proposed ZDPC has been performed. The results are compared to other recent techniques to demonstrate the superiority and feasibility of the proposed strategy.

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

“…To date, the conventional STF-pq theory algorithm still produces a non-sinusoidal reference current [7,40,42] and thus forces the SAPF to operate based on a direct current controlled (DCC) scheme [43][44][45]. From previous literature [45][46][47], it is revealed that the SAPF switching operation produces switching ripples which potentially degrade the THD value of the mitigated source current.…”

“…Under non-sinusoidal source voltage conditions, source voltage in α-β domain can actually be decomposed into dc and ac components as follows: In order to deal with non-sinusoidal source voltage conditions, a self-tuning filter (STF) is commonly applied to process the source voltage so that dc components of the source voltage can be extracted, serving as reference voltage to ensure in-phase operation of SAPF with the designated power system. In [7,40,42], the transfer function of STF for source voltage processing (after performing Laplace transformation) can be summarized as follows:…”

“…From [7,40,42], in order to achieve the best filtering performance of STF in extracting dc components of load currents, K 2 is commonly set at a value between the range of 20 to 80, and f c is fixed at 50 Hz.…”

“…A better alternative is by incorporating a self-tuning filter (STF) [7,40]. In the context of SRF-based reference current generation algorithms, the STF algorithm has been applied to enhance the ability of phase-locked loops (PLLs) to work under non-sinusoidal source voltages [41].…”

“…Nevertheless, the shunt-typed active power filter (SAPF) [4][5][6][7] is the most effective solution to current harmonics issues. Additionally, it is also capable of improving PF performances [7][8][9][10][11] by reducing reactive power burden on the power system, while mitigating harmonic currents. Generally, SAPF performs by injecting opposition current (simply known as injection current) back to the harmonic-polluted power system which allows the polluted source current to regain its sinusoidal characteristic with fundamental frequency.…”