Optimized Neuro-Adaptive Third-Order Sliding Mode Control With High-Gain Differentiator for Enhanced Photovoltaic System Performance: Simulation and Experimental Validation

BackgroundTechnology is deployed to take the advantage of the ultimate energy from the sun (solar energy) to be used as heat or clean electricity. This energy is classified as “sustainable energy” or “renewable energy” because it requires a short period to naturally replenish the used energy. The application of solar energy involves the conversion of the natural energy resource into a usable form, either as heat or as electricity. The device consists of solar cells made from semiconductor materials, such as silicon, cadmium telluride, gallium arsenide, and so on. Solar potential is both location- and climate-dependent; it is characterised by low energy intensity and intermittency, which limit its application; an improvement in photovoltaic (PV) system performance will facilitate more deployment of the clean electricity system. Therefore, this study provides PV potential and system information required for reliable and optimised solar PV systems at chosen locations. This work uses a 5-stage solar PV system assessment and system performance evaluation utilising Solargis Prospect software. The PV potential and system performance of nine selected site locations in South Africa was conducted using this method. The nine PV site locations are Bloemfontein (Free State), Germiston (Gauteng), Mahikeng (North-West), Mbombela (Mpumalanga), Musgrave (Kwazulu-Natal), Musina (Limpopo), Port Nolloth (Northern Cape), Port Elizabeth (Eastern Cape), and Worcester (Western Cape).ResultThe results of the study were categorised into PV meteorological and system performance parameters as follows. Photovoltaic meteorological parameters—the site in Mahikeng has the highest global horizontal irradiance (GHI), 2156 kWh/m2, and a corresponding specific PV power output (1819.3 kWh/kWp), closely followed by Bloemfontein (2111.5 kWh/m2, 1819.4 kWh/kWp) and Port Nolloth (2003.2 kWh/m2, 1820.5 kWh/kWp). The lowest GHI (1645.1 kWh/m2) and specific PV power output (1436.6 kWh/kWp) were recorded in Musgrave. Photovoltaic system performance parameters—the range of performance ratio (PR) between 75.8 and 77.7% was reported across the nine sites. This ratio met the acceptable benchmark of PR. The highest specific PV power output loss, 118.8 kWh/kWp, was obtained at sites in Bloemfontein, Mahikeng, and Port Nolloth, while the lowest, 93.8 kWh/kWp, was in Musgrave.ConclusionsThe results of the solar PV potential assessment and the evaluation of PV systems performance in the chosen sites across the nine provinces of South Africa show huge PV potential and energy yield. From the results, it was observed that the range of the yearly average of: (1) GHI among the sites is 1645.1–2156 kWh/m2; (2) direct normal irradiation among the sites is 1785.3–2559.3 kWh/m2; (3) diffuse horizontal irradiation among the sites is 512.5–686kWh/m2; (4) global tilted irradiation among the sites is 1849.2–2397.1 kWh/m2; (5) the temperature (TEMP) among the sites is 16–23 °C; (6) specific PV power output (PVOUT specific) among the sites is 1436.6–1820.5 kWh/kWp; (7) total PV power output (PVOUT total) among the sites is 14.366–2397.1 MWh; and (8) the performance ratio among the sites is 75.8–77.7%. Based on the solar resource and performance results of the PV system obtained, the deployment of monocrystalline solar PV technology in all the considered sites across South Africa is technically viable.

Optimization of grid power quality using third order sliding mode controller in PV systems with multilevel inverter

The photovoltaic (PV) panels and system performance is affected by the tilt angle and orientation, as these factors investigate the total amount of irradiation intensity received by the related surface of a panel. This research conducts an experiment with the variation of tilt angle under certain operating conditions. In addition, the impact of surface tilt angle with various irradiation levels on PV performance is analyzed numerically using Finite Element Method (FEM). The effect of varying the tilt angle from 0° to 80° on PV performance is studied under both variable and constant irradiation conditions. For every 100 W/m2 irradiation intensity increased, the solar cell temperature and power output increase by 5.34°C and 5.94 W for numerical as well as by 5.37°C and 5.83 W for experimental results, respectively. For every 5° increments in surface tilt angle, the average power output and solar cell temperature drop by 1.55 W and 1.12°C for numerical and by 1.59 W and 1.09°C for experimental case, while efficiency falls by 0.35% and 0.33% for experimental and numerical cases, respectively. The optimum tilt angle can maximize the irradiation on a panel and thereby the performance of the panel.

In the last decade, research centered around the fault diagnosis of rotating machinery using non-contact techniques has been significantly on the rise. For the first time worldwide, innovative techniques for the diagnosis of rotating machinery, based on electrical motors, including generic, nonlinear, higher-order cross-correlations of spectral moduli of the third and fourth order (CCSM3 and CCSM4, respectively), have been comprehensively validated by modeling and experiments. The existing higher-order cross-correlations of complex spectra are not sufficiently effective for the fault diagnosis of rotating machinery. The novel technology CCSM3 was comprehensively experimentally validated for induction motor bearing diagnosis via motor current signals. Experimental results, provided by the validated technology, confirmed high overall probabilities of correct diagnosis for bearings at early stages of damage development. The novel diagnosis technologies were compared with existing diagnosis technologies, based on triple and fourth cross-correlations of the complex spectra. The comprehensive validation and comparison of the novel cross-correlation technologies confirmed an important non-traditional novel outcome: the technologies based on cross-correlations of spectral moduli were more effective for damage diagnosis than the technologies based on cross-correlations of the complex spectra. Experimental and simulation validations confirmed a high probability of correct diagnosis via the CCSM at the early stage of fault development. The average total probability of incorrect diagnosis for the CCSM3 for all experimental results of 8 tested bearings, estimated via 6528 diagnostic features, was 1.475%. The effectiveness gains in the total probability of incorrect diagnosis for the CCSM3 in comparison with the CCCS3 were 26.8 for the experimental validation and 18.9 for the simulation validation. The effectiveness gains in the Fisher criterion for the CCSM3 in comparison with the CCCS3 were 50.7 for the simulation validation and 104.7 for the experimental validation.

This paper proposes an innovative approach to improve the performance of grid-connected photovoltaic (PV) systems operating in environments with variable atmospheric conditions. The dynamic nature of atmospheric parameters poses challenges for traditional control methods, leading to reduced PV system efficiency and reliability. To address this issue, we introduce a novel integration of fuzzy logic and sliding mode control methodologies. Fuzzy logic enables the PV system to effectively handle imprecise and uncertain atmospheric data, allowing for decision-making based on qualitative inputs and expert knowledge. Sliding mode control, known for its robustness against disturbances and uncertainties, ensures stability and responsiveness under varying atmospheric conditions. Through the integration of these methodologies, our proposed approach offers a comprehensive solution to the complexities posed by real-world atmospheric dynamics. We anticipate applications in grid-connected PV systems across various geographical locations and climates. By harnessing the synergistic benefits of fuzzy logic and sliding mode control, this approach promises to significantly enhance the performance and reliability of grid-connected PV systems in the presence of variable atmospheric conditions. On the grid side, both PSO (Particle Swarm Optimization) and GA (Genetic Algorithm) algorithms were employed to tune the current controller of the PI (Proportional-Integral) current controller (inverter control). Simulation results, conducted using MATLAB Simulink, demonstrate the effectiveness of the proposed hybrid MPPT technique in optimizing the performance of the PV system. The technique exhibits superior tracking efficiency, achieving a convergence time of 0.06 s and an efficiency of 99.86%, and less oscillation than the classical methods. The comparison with other MPPT techniques highlights the advantages of the proposed approach, including higher tracking efficiency and faster response times. The simulation outcomes are analyzed and demonstrate the effectiveness of the proposed control strategies on both sides (the PV array and the grid side). Both PSO and GA offer effective methods for tuning the parameters of a PI current controller. According to considered IEEE standards for low-voltage networks, the total current harmonic distortion values (THD) obtained are considerably high (8.33% and 10.63%, using the PSO and GA algorithms, respectively). Comparative analyses with traditional MPPT methods demonstrate the superior performance of the hybrid approach in terms of tracking efficiency, stability, and rapid response to dynamic changes.

Experimental study on the effect of dust deposition on photovoltaic performance at various tilts in semi-arid environment

This paper presents the results of a study conducted by Itron for the California Public Utilities Commission (CPUC) to examine the relationships between solar photovoltaic (PV) performance, costs, and PV incentive structures. The intent is twofold. The first intent is to create a baseline of PV performance and costs using actual performance data and reported costs from a large number of PV systems installed and operating in California. The second intent is to examine how PV performance and projected PV cost reductions can influence PV incentive payments. This study should help provide policy makers responsible for developing PV incentive programs with information that will result in incentive structures that fairly and transparently reward improved PV cost and performance while simultaneously providing a reasonable pathway to move PV towards an incentive-free market environment. PV performance monitoring data for over one hundred operating commercial, industrial, and institutional solar PV systems are combined with projected electricity retail rates and future PV costs within a breakeven levelized cost model to produce associated PV incentive levels. Preliminary results for 39 prototype PV market scenarios provide insights into how PV incentive levels can be set to take advantage of utility-specific electricity retail rates, PV configuration and location, and projected PV cost reductions while facilitating the development of PV systems that can compete without incentives. Potential implications of these performance and cost-effectiveness results are discussed with respect to PV incentive programs and PV markets.

In the current days there is an increment of interest in damage detection methods, aimed to assure the operating status of existing structures or for intensifier quality control on production line. These are only some of the applications whereby damage detection methods have been dev eloped. In the past several researches have been addressed towards damage detection using vibration analysis, especially through mode shape and natural frequencies changes. In the preset study correlation methods based on ODSs have been developed. The structure was taken under consideration is steel plate. The correlation methods presented are based on the comparison of the ODSs generated by two FEM models of the plate, one defined as pristine and the other as damaged. The latter has been modelled adding a single node mass element to the model surface. This mass element was chosen to simulate a magnet attached to the surface plate in the experimental case. Several simulations have been performed using combinations of mass and positions, for a total of 16 cases. Studying the correlations between a ODSs pair, given by the same excitation frequency and position, is possible to identify the presence of damage in the structure. The experimental model validation has been performed using the best excitation condition obtained by simulation, which can point out large differences between the damaged ODS and undamaged ODS.

The present study aimed at performing a hydrodynamic analysis of the safety device's behavior in a gas relay, using computational fluid dynamics techniques and experimental data validation obtained in a protective relay pilot unit (PRP) using different safety flaps geometries for fault detection within high-power transformers. The proposed methodology was carried out in four stages: (i) development of computational meshes from the three-dimensional geometry of the protective relay and safety flaps; (ii) specification of the physical properties of fluids, boundary conditions, and fluid dynamic models; (iii) obtaining speed profiles, flap angle, oil flow and system pressure difference; and (iv) comparison of simulated and experimental data. The devices installed in the relay showed satisfactory performance for failures caused by the oil volumetric expansion. It was observed that from the flap 10° tilt, the orifice ceases to be the preferred path oil, reducing detection sensitivity of the flow. Using the CFD (computational fluid dynamics) computational tool, it was possible to understand the flow behavior within the relay, allowing to detect quickly and efficiently cases of failure with oil expansion.

The performance loss rate (PLR) is a vital parameter for the time-dependent assessment of photovoltaic (PV) system performance and health state. Although this metric can be calculated in a relatively straightforward manner, it is challenging to achieve accurate and reproducible results with low uncertainty. Furthermore, the temporal evolution of PV system performance is usually nonlinear, but in many cases a linear evaluation is preferred as it simplifies the assessment and it is easier to evaluate. As such, the search for a robust and reproducible calculation methodology providing reliable linear PLR values across different types of systems and conditions has been the focus of many research activities in recent years. In this paper, the determination of PV system PLR using different pipelines and approaches is critically evaluated and recommendations for best practices are given. As nonlinear PLR assessments are fairly new, there is no consent on how to calculate reliable values. Several promising nonlinear approaches have been developed recently and are presented as tools to evaluate the PV system performance in great detail. Furthermore, challenges are discussed with respect to the PLR calculation but also opportunities for differentiating individual performance losses from a generic PLR value having the potential of enabling actionable insights for maintenance.

A model for effect of partial shading on PV panels with experimental validation

The control of speed ratio on Continuously Variable Transmission (CVT) is one of the key problems for CVT development. In this paper, a nonlinear Sliding Mode Control (SMC) law of switched systems is designed and employed to control the CVT shifting. Because the CVT shifting control system contains discontinuous characteristics, the way of Filippov solution with discontinuous righthand side is used to design the sliding mode controller. Through the validation of simulation and on-board experiments, it can be concluded that the nonlinear SMC law is a better candidate to control the CVT shifting.

The accuracy of photovoltaic (PV) performance forecasts is essential for improving grid penetration, fault detection, and financing of new installations. Failing to account for the spectral influence on PV performance can lead to weekly errors of up to 14% even for relatively stable technologies such as polycrystalline silicon. There exist a range models, known as spectral correction functions (SCFs), to account for the spectral influence on PV performance forecasts. These SCFs use different methods to characterise both the shift in PV performance due to the spectrum, and the solar spectrum itself. This review analyses the merits and limitations of seven commonly used spectral characterisation indices — five proxy variables (air mass, clearness index, precipitable water, aerosol, diffuse solar radiation ratio) and two variables extracted from the spectral distribution (average photon energy, depth of a water absorption band). The same analytical approach is adopted to review a further four indices (mismatch factor and its variants, (weighted) useful fraction, normalised short-circuit current) that are commonly used to characterise the variation in PV performance due to the solar spectrum. A review of ten SCFs that are based on these indices is undertaken to analyse the current state of the art of spectral correction modelling. The results of the review show that whereas some proxy-variable methods offer a simple and convenient way to account for the spectral influence in PV performance forecasts, they are surpassed in terms of accuracy by SCFs based on parameters derived directly from the spectrum, such as the average photon energy and the depth of spectral absorption bands. A decision-making framework is proposed to guide PV performance modellers in their choice of spectral correction model. The framework considers system specifications, climate, data availability, etc. The results of this work may be applied in, for example, software packages for PV performance forecasting to enable more accurate case-specific power forecasts. In future work, a standardised comparison of all SCFs and their respective indices is necessary to quantify the differences between a wider range of models than is currently available in the literature and substantiate the proposed framework.

High-efficiency MPPT strategy for PV Systems: Ripple-free precision with comprehensive simulation and experimental validation

Assessing the combined effects of local climate and mounting configuration on the electrical and thermal performance of photovoltaic systems. Application to the greater Sydney area