The effects of measuring devices/sensors on improving the power quality (PQ) of electric networks are studied in this paper. In this context, improving the performance of an LCL-type grid connected to a three-phase three-wire shunt active filter (SAF) in the presence of voltage perturbations is studied. In order to ensure the high-quality performance of LCL-SAF in the presence of voltage perturbations, the robust continuous second-order sliding mode controller (2-SMC), including twisting and super-twisting controllers, and continuous higher-order sliding mode controller (C-HOSMC)-based approaches are employed. These controllers, whose outputs are processed by pulse-width modulation (PWM), allow minimization of the phase shift and prevent the generation of discontinuous chattering commands, which can severely damage the VSI components. Moreover, an integration of a generalized instantaneous power identification algorithm with an advanced phase locked loop (PLL) was proposed and experimentally tested to validate the effective performances of SAF under severe perturbations. Additionally, the studied approaches were tested via simulations taking into account a conventional nonlinear industrial load in a real textile factory environment, using measurements provided by power quality analyzers. Finally, the effects of the measuring devices, including the current and voltage sensors, on the accuracy and reliability of the SAF and, consequently, on the PQ of the electric power grid were studied via simulations and experimentally. The results of this study support the validity of the recently published patent.

This paper presents a free-harmonic AC/DC/AC converter structure using a novel modulation approach for Asymmetrical Cascade H–Bridge Multi–Level Inverter (ACHB–MLI) and, conventional rectifiers combined with a shunt active filter, for grid integration. The novel approach SMT-SHE combines two modulation techniques: the Staircase Modulation Technique (SMT) and the Selective Harmonics Elimination (SHE). SMT-SHE approach achieves a sinusoidal-like output stepping voltage with variable output voltage amplitude and free of wide band or/and specific harmonics to fulfill the sensitive loads specifications; by determining the appropriate SHE switching angles. The precalculated switching angles are optimized to minimize the number of H–bridge modules and lower the DC capacitors rating. Furthermore, a restriction on the switching angles is proposed to prevent the appearance of undesired harmonics (zeros, even) and consequently overcome the limitation of the SHE algorithm applicability. Finally, a real case study in textile factory is conducted, using real measurements provided by power quality analyzer measuring devices, to validate the proposed AC/DC/AC converter supplying a sensitive load of 50 kVA, given by an asynchronous motor drive.

This article presents a compact structure of Shunt Active Photovoltaic Filter based on a Cascaded H-Bridge Multi-Level Inverter (SAF-PV/CHB-MLI) to eliminate electrical perturbations caused by nonlinear loads and to generate MPPT of PV generators. The SAF-PV/CHB-MLI structure, while injecting the maximum current of PV generators, opts to increase the apparent switching frequency, reduces the coupling/output filter size, improves grid-side power quality, generates sinusoidal-like output stepping voltage, and minimizes voltage stresses on IGBTs devices. To achieve these objectives, the SAF-PV/CHB-MLI structure is configured for n HB module per phase/cluster, combined with an appropriate common control strategy for both active filtering and PV generation. The p - q current identification algorithm is adapted/modified to include a P&O algorithm for MPPT detection and a developed PLL to ensure reliable operation under grid distortion conditions. The common control strategy comprises three complementary control loops: the injected current controller for perturbation compensation and maximum PV current injection, the individual cluster voltage balancing controller, and the overall DC voltage regulator which is incorporated within the adapted/modified p-q algorithm. Then, a Multi-Carriers Phase-Shifted PWM (PS-PWM) is adopted to ensure the required individual and apparent switching frequencies, while reducing the sideband harmonic components' impact. A trade-off among the HB modules number, IGBTs rating, individual and apparent switching frequencies, and the accumulative output voltage is elaborated to create reliable and economical structure that meets industrial application recommendations. To validate the proposed structure's performance, a case study is conducted for textile industrial factory suffering from harmonic impact on its main Sensitive Load (SL) textile machine of almost 50 kVA; site measurements using power-quality analyzer devices are collected. A numerical model of the factory's network was developed to investigate the proposed structure performance on SL.

In this work, we represent a shunt active power filter (SAPF) based on a serial three-phase flying capacitor multilevel inverter (FCMI) controlled by a Petri Nets representation (PNs). This structure is chosen for its significant performances. In fact, the use of the FCMI within the SAPF makes it possible to increase the apparent switching frequency of the structure in order to reduce the value then the volume and weight of the inductance of the output filter. Besides, the FCMI allows the synthesis of a high-voltage signal using low-voltage semiconductor components. Therefore, improving the reliability of this structure leads to the improvement of the dynamics of the SAPF. This paper deals with a new control methodology based on PNs to regulate the flying capacitor voltages and the reference currents issued by the instantaneous active and reactive power theory. Compared to a conventional SAPF composed by a classical two-level inverter and controlled by a simple PWM control, simulation results demonstrate that our proposed control enhances the dynamic system and the power quality by reducing the total harmonic distortion (THD) satisfying the limits of IEEE standards.

The Shunt Active Filter (SAF) is an effective solution for mitigating electrical perturbations in power networks. SAFs usually consist of a voltage source inverter (VSI) with lossy transistors and bulky inductors. In this context, this article proposes analytical models to evaluate the losses and efficiency of a SAF. The models include conduction and switching losses in the transistors and diodes and are valid for both IGBT and SiC MOSFET transistors. The methodology consists of analysing the current waveform to separate the portion flowing through the transistor or diode. IGBT and SiC MOSFET are compared in two cases: firstly, the classic SAF operation with harmonic and reactive power compensation and, secondly, in the case of power injection by a photovoltaic panel or batteries, in addition to the classic SAF operation. The results are validated with real manufacturer data. A step-by-step comparison shows a good accuracy of the model. Therefore, the developed methodology is useful for a SAF designer to select relevant components for the converter and to estimate the efficiency of the system accurately and quickly.