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Grid-connected photovoltaic (PV) systems impose challenges like voltage fluctuations, low system inertia, and power quality issues. The need to tackle these challenges led to the introduction of flexible power point tracking (FPPT), where the PV power output is controlled by an energy management system, rather than solely operating the PV systems on the maximum power point. The requirement of fast transient response implies that algorithms such as the one proposed in this article are desirable. The proposed algorithm uses the secant method to achieve significantly improved results in comparison to the existing methods. The method also simplifies the prediction of variations during changes in the environment and power reference, hence, results in reduced oscillation around the set-point and faster convergence. Experimental validation is presented in this article for supporting the claims. The results in terms of accuracy, convergence rate, steady-state oscillations, and cumulative error are bench-marked against one of the most recent FPPT methods. [ABSTRACT FROM AUTHOR]

• This research presents and investigates the experimental measurements of power quality parameters in-field on 8 kWp PV system connected to the LV distribution network in Electronics Research Institute, Egypt. Also, This research aims to investigate unity power factor and constant reactive power as two different functions of the PV inverter. • Statistical analysis of each harmonic, power factor and total harmonic distortion are analyzed and presented under different loading conditions and two different functions. • The focus is set on the characterization of relationship between current harmonics of PV inverter and voltage harmonics prevailing in the LV system at unity power factor and constant reactive power. • This paper proposes mathematical models in order to characterize current total harmonic distortion and power factor. The accuracy of proposed empirical models was compared with previous research studies and presented the highest accurate results. Since the penetration of photovoltaic (PV) systems in the Low Voltage (LV) distribution network is increasing, the need to characterize and model the effect of these systems on power quality parameters is an up-to-date issue. Also, the reactive power capability of PV inverter should be defined and discussed. This research presents and investigates the experimental measurements of power quality parameters in-field on 8 kWp PV system connected to the LV distribution network in Electronics Research Institute, Egypt. This research aims to investigate unity power factor and constant reactive power functions as two different operation modes of PV inverter based on the measurements at PV inverter output and the grid point without local loads at off days of the governmental building in order to avoid load effects on the PV inverter parameters. Field measurement data were recorded using the power quality analyzer CA8335. Statistical analysis of each harmonic, power factor and total harmonic distortion are analyzed and presented under different loading conditions and two different functions of the PV inverter. The focus is set on the characterization of the relationship between current harmonics of PV inverter and voltage harmonics prevailing in LV system. It is found that the PV inverter presents high current total harmonic distortion levels at power levels below its rated value. This paper proposes mathematical models in order to characterize the current total harmonic distortion and the power factor at two different operation modes. The accuracy of the proposed empirical models was compared with previous research studies and presented the highest accurate results. The presented results are useful for the manufacturer of the tested PV inverter. [ABSTRACT FROM AUTHOR]

The insertion of photovoltaic solar energy has increased considerably over the past few years, with remarkable growth since 2005. It is essential that the electrical energy delivered by the photovoltaic system to the grid has an acceptable quality level. This paper presents test results of power factor and harmonic distortion content in grid connected inverters for photovoltaic systems. Several tests of ten commercially available inverter models from three different manufacturers were performed at the Laboratory of Solar Energy (Labsol) at the Federal University of Rio Grande do Sul (UFRGS), using a test bench with a power analyzer. The power factor and total harmonic distortion in current curves were mathematically modeled as a function of relative power in order to be used in computer simulation of photovoltaic systems. For power loads close to the nominal values, the harmonic content was found to be low and in accordance with the standard requirements. Nevertheless, at low loading levels the inverters may inject high levels of harmonics into the grid. [ABSTRACT FROM AUTHOR]

The application of photovoltaic (PV) as a source of electrical energy in the distributed generation (DG) systems are gaining more attention with the advances in power electronics technology. The one of the key technologies in the PV based DG systems is grid connected inverter that is utilized to interface PV power systems into the utility grid. Multilevel multifunctional grid connected inverters (ML-MFGCIs) are new breed of power converter used in large scale PV applications and have superior advantages such as lower switching power dissipation, lower harmonic distortion and lower electromagnetic interference (EMI) outputs. ML-MFGCIs perform the high quality power from PV systems and provide flexible functionality with improved power quality (PQ), voltage and reactive power support and increased capability of the auxiliary service for the utility grid. This paper presents a detailed analysis of various ML-MFGCI configurations for 1-phase and 3-phase systems and control strategies to compensate the different PQ problems. Almost 100 papers including the practical applications and recent research studies on ML-MFGCIs are reviewed and analysed. [ABSTRACT FROM AUTHOR]

As more distributed generators join the utility grid, the concern of possible undetected islanding operation increases. This concern is due to the safety hazards this phenomenon imposes on the personnel and equipment. Passive anti-islanding detection methods monitor grid parameters to detect islanding, whereas active methods inject a perturbation into the current waveform to drive these parameters out of limit when islanding occurs. The performance of active methods, such as conventional active frequency drift (AFD), is limited by the amount of total harmonic distortion (THD) they inject into the grid, which defines its nondetection zone. In this paper, an improved AFD anti-islanding method is presented based on a different current distortion injection waveform. The proposed method generates 30% less THD compared to classic AFD, resulting in faster island detection and improved nondetection zone. The performance of the proposed method is derived analytically, simulated using Matlab and verified experimentally using a prototype setup. A single-phase grid-tied photovoltaic distributed generation system is used for the simulation and experimental setup, and considered as potential application. [ABSTRACT FROM AUTHOR]