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[IEEE 2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC) - Santos, Brazil (2019.12.1-2019.12.4)] 2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC) - Optimal Voltage Coordinated Control for Grid-connected Photovoltaic Systems
摘要： The intermittent penetration of Grid-connected photovoltaic systems and load changing in distribution feeders can cause voltage ?uctuation. This paper aims to analyze the performance of different power control strategies to avoid overvoltage in MV feeders. The strategies use Volt/Var control and Volt/Watt control techniques to ?nd the optimal active or reactive power to be injected/absorbed by the PV inverters with the aim to minimize the voltage deviation and power losses and also coordinate the grid-connected photovoltaic system with the voltage regulation devices of distribution feeders. The strategies are tested in the IEEE 13 node test feeder.
关键词： active and reactive power control,grid-connected photovoltaic systems,Voltage regulation
更新于2025-09-23 15:21:01
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Nonlinear Analysis Methods Applied on Grid-Connected Photovoltaic (PV) Systems Driven by Power Electronic Converters
摘要： A novel method of analysis is deployed in detail on the basis of nonlinear systems theory with aim to design suitable controllers with guaranteed stability for grid-connected photovoltaic (PV) systems driven by power converters. By this method, all the system nonlinearities are taken into account to allow a reliable analysis in a wide range of operation and to avoid instabilities that as shown in the paper can be occurred by inappropriate design. To this end, firstly a detailed accurate nonlinear dynamic model is presented for the PV system by including a cascade-mode control scheme. Then, taking into account the closed-loop system and incorporating the concept of input-to-state stability (ISS), a rigorous novel stability analysis is developed which achieves to prove asymptotic stability of the desired equilibrium point. A multi-step process is deployed in which the control loops operating in cascade-mode are involved. However, since the cascaded-mode control scheme and analysis is based on the time-scale separation principle, a systematic tuning method is conducted for the accurate gain selection of both inner-loop and outer-loop controllers which is based on the construction of suitable Lyapunov functions. To further validate the overall analysis, experimental results are carried out.
关键词： nonlinear analysis,grid-interaction,Photovoltaic systems,stability,power converter control design
更新于2025-09-23 15:21:01
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Efficiency analysis of photovoltaic systems
摘要： The goal of the study was to analyse the efficiency of two existing photovoltaic micro-installations with the power of approx. 40 kWp. The main factor differing the two installations being analysed was the arrangement of modules in relation to the sides of the world, one is south-west and the other is east-west. The total yield of electrical energy in 2017 from the south-west installation was higher and amounted to 34980 kWh. For the east-west installation the amount of energy generated was equal to 31180 kWh. 4 methods of forecasting electrical energy yield were discussed. Simple computational method proved to be the best method for both installations.
关键词： photovoltaic systems,renewable energy,efficiency
更新于2025-09-23 15:21:01
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Photovoltaic Degradation Rate Affected by Different Weather Conditions: A Case Study Based on PV Systems in the UK and Australia
摘要： This article presents the analysis of degradation rate over 10 years (2008 to 2017) for six different photovoltaic (PV) sites located in the United Kingdom (mainly affected by cold weather conditions) and Australia (PV affected by hot weather conditions). The analysis of the degradation rate was carried out using the year-on-year (YOY) degradation technique. It was found that the degradation rate in the UK systems varies from ?1.05% and ?1.16%/year. Whereas a higher degradation ranging from ?1.35% to ?1.46%/year is observed for the PV systems installed in Australia. Additionally, it was found that in the Australian PV systems multiple faulty PV bypass diodes are present due to the rapid change in the ambient temperature and uneven solar irradiance levels influencing the PV modules. However, in cold weather conditions (such as in the Northern UK) none of the bypass diodes were damaged over the considered PV exposure period. Furthermore, the number of PV hot spots have also been observed, where it was found that in the UK-based PV systems the number of hot spotted PV modules are less than those found in the Australian systems. Finally, the analysis of the monthly performance ratio (PR) was calculated. It was found that the mean monthly PR is equal to 88.81% and 86.35% for PV systems installed in the UK and Australia, respectively.
关键词： performance analysis,photovoltaic systems,performance ratio,degradation,hot-spots
更新于2025-09-23 15:21:01
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Adaptive backstepping approach for dc-side controllers of Z-source inverters in grid-tied PV system applications
摘要： Z-source inverters (ZSIs) are single-stage power converters with both voltage buck and boost capabilities provided by the unique impedance network and the ability to operate during shoot-through states. This study proposes a novel non-linear adaptive backstepping method for dc-side controllers in a multi-loop control scheme of the ZSI in grid-tied photovoltaic (PV) systems. Despite the variability of the capacitor and inductor values in the ZSI impedance network, the proposed controller guarantees robust and stable operation under varying levels of PV irradiance and temperature. The shoot-through duty ratio of the ZSI is obtained directly from the output of an MPPT algorithm and the measured PV and inductor currents. This strategy overcomes the disadvantages of the conventional approach such as the non-minimum phase at the dc side of the ZSI. It also eliminates the need to linearise the voltage/current characteristics of the PV arrays and ZSI model. The ac-side controllers consist of an outer proportional–integral voltage controller and an inner deadbeat current controller to achieve unity power factor and stable capacitor voltage in spite of grid voltage fluctuations. The efficacy of the proposed adaptive backstepping controller and the multi-loop control scheme is validated by offline and hardware-in-the-loop real-time simulations.
关键词： maximum power point tracking,Z-source inverters,adaptive backstepping control,grid-tied inverters,photovoltaic systems
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Dopant Diffusion through Selective Surface Regions to Improve Efficiency in Micro/Nano Textured Thin Solar Cells
摘要： We introduce a simple method to improve efficiency in micro/nano textured solar cells by diffusing a dopant through selective surface regions. This method is effective when the texture size is comparable to or smaller than the characteristic diffusion length. In this size regime, strong inhomogeneity in the dopant concentration often develops in the cells. In our case, the texture is an array of nanopyramidal dips on thin crystalline silicon solar cells. Our simulations for the texture show strong inhomogeneity in the dopant concentration along the textured surface. The strong inhomogeneity creates electrically inactive regions in the texture. With our doping method, our simulations show that the inhomogeneity can be significantly reduced to enhance charge collection efficiency. We confirm this prediction by directly measuring photovoltaic efficiencies of solar cells fabricated with and without using our doping method of selective diffusion. Our experiments demonstrate that our selective dopant diffusion enhances the efficiency from 12.5% to 13.3% for free- standing 15-?m-thick silicon solar cells textured with periodic nanopyramidal dips. Our method would be generally applicable for other micro/nano structures, semiconductor materials, and optoelectronic devices.
关键词： photovoltaic systems,solar power generation,generation,Power engineering and energy,energy,photovoltaic cells
更新于2025-09-23 15:19:57
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Robust code-based modeling approach for advanced photovoltaics of the future
摘要： Modeling and simulation of photovoltaics help to reduce development costs, design turnaround time and facilitates better techno-economic decisions. However, there is a current need to generate new theories, algorithms, applications and software in order to increase the contribution of solar energy to the global energy supply. For future advancements in the field of photovoltaics, robust techniques for PV modeling, simulation, visualisation and design are required to overcome the limitations of the current approaches. This study proposes the Code-Based Modeling (CBM) approach as a potent approach to facilitate the study of PV technologies. Experimental data were synthesised and used for coding and training of the code-based (CB) model; followed by a validation of the trained model using commercial PV modules. Results clearly show that the model can repeatedly and reliably predict the short circuit current, maximum power point, open circuit voltage with 0%, < 2% and < 10% deviations, respectively. Furthermore, instances of the applicability of the CBM approach in the study of the thermodynamics of PV, solar cell materials characterisation, PV systems design and power monitoring were presented. Above all, CBM approach accepts user-defined functions and therefore presents new opportunities for scientists and engineers to advance model-based investigations of the photovoltaics beyond the current state-of-the-art.
关键词： Code-based modeling,Block-based modeling,Photovoltaic tools,Simulation,Photovoltaic systems
更新于2025-09-23 15:19:57
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Fully decentralized robust backstepping voltage control of photovoltaic systems for DC islanded microgrids based on disturbance observer method
摘要： In this paper, a new backstepping-based nonlinear technique for control of photovoltaic systems in DC islanded microgrids (MGs) is proposed. In contrast to most existing droop/non-droop control strategies that require an exact model of the system including line impedances, loads, other distributed generation units (DGUs) parameters, and even the MG configuration, the proposed method is taking dynamics and uncertainties into account using a designed disturbance observer. Moreover, the proposed method rapidly reaches the reference values and exhibits a more accurate robust performance using local quantities measurement, irrespective of parametric uncertainties, unmodeled dynamics, unknown loads, disturbances, and the number/structure of DGs within the MG. Finally, a low-voltage DC MG is built where the robust performance of the proposed method for different operating conditions including load variation, tracking capability, nonlinear loads, and plug-play of DGs is verified.
关键词： robust control,Backstepping control,disturbance observer,photovoltaic systems,microgrids
更新于2025-09-23 15:19:57
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An Interval-Arithmetic-Based Approach to the Parametric Identification of the Single-Diode Model of Photovoltaic Generators
摘要： Parametric identi?cation of the single diode model of a photovoltaic generator is a key element in simulation and diagnosis. Parameters’ values are often determined by using experimental data the modules manufacturers provide in the data sheets. In outdoor applications, the parametric identi?cation is instead performed by starting from the current vs. voltage curve acquired in non-standard operating conditions. This paper refers to this latter case and introduces an approach based on the use of interval arithmetic. Photovoltaic generators based on crystalline silicon cells are considered: they are modeled by using the single diode model, and a divide-and-conquer algorithm is used to contract the initial search space up to a small hyper-rectangle including the identi?ed set of parameters. The proposed approach is validated by using experimental data measured in outdoor conditions. The information provided by the approach, in terms of parametric sensitivity and of correlation between current variations and drifts of the parameters values, is discussed. The results are analyzed in view of the on-site application of the proposed approach for diagnostic purposes.
关键词： parametric identi?cation,interval arithmetic,photovoltaic systems,single-diode model
更新于2025-09-23 15:19:57
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Operational Performance and Degradation Influenced Life Cycle Environmentala??Economic Metrics of mc-Si, a-Si and HIT Photovoltaic Arrays in Hot Semi-arid Climates
摘要： Life cycle metrics evolution specific to the climate zone of photovoltaic (PV) operation would give detailed insights on the environmental and economic performance. At present, vast literature is available on the PV life cycle metrics where only the output energies ignoring the degradation rate (DR) influence. In this study, the environ-economic analysis of three PV technologies, namely, multi-crystalline silicon (mc-Si), amorphous silicon (a-Si) and hetero-junction with an intrinsic thin layer (HIT) have been carried out in identical environmental conditions. The energy performance parameters and the DR rate of three PV technologies are evaluated based on the monitored real time data from the installation site in hot semi-arid climates. The assessment demonstrates that the HIT PV module technology exhibits more suitable results compared to mc-Si and a-Si PV systems in hot semi-arid climatic conditions of India. Moreover, energy metrices which includes energy payback time (EPBT), energy production factor (EPF) and life cycle conversion efficiency (LCCE) of the HIT technologies are found to be 1.0, 24.93 and 0.15 years, respectively. HIT PV system has higher potential to mitigate the CO2 and carbon credit earned compared to mc-Si and a-Si PV system under hot semi-arid climate. However, the annualized uniform cost (UAC) for mc-Si (3.60 Rs/kWh) and a-Si (3.40 Rs/kWh) are more admissible in relation to the HIT (6.63 Rs/kWh) PV module type. We conclude that the approach of considering DR influenced life cycle metrics over the traditional approach can support to identify suitable locations for specific PV technology.
关键词： annualized uniform cost,amorphous silicon,crystalline solar cells,life cycle assessment,PV cells,energy payback time,life cycle metrics,HIT,photovoltaic systems,degradation rate
更新于2025-09-23 15:19:57