Fault identification-based voltage sag state estimation using artificial neural network

This paper presents an artificial neural network (ANN) based approach to identify faults for voltage sag state estimation. Usually ANN cannot be used to abstract relationship between monitored data and arbitrarily named fault indices which are not related at all logically in numerical level. This paper presents a novel approach to overcome this problem. In this approach, not only the networks are trained to adapt to the given training data, the training data (the expected outputs of fault indices) is also updated to adapt to the neural network. During the training procedure, both the neural networks and training data are updated interactively. With the proposed approach, various faults can be accurately identified using limited monitored data. The approach is robust to measurement uncertainty which usually exists in practical monitoring systems. Furthermore, the updated fault indices are able to suggest the difference of the impact of various faults on bus voltages

A simple method for parameter extraction of a PV module

This is an accepted manuscript of a conference contribution presented at ECRES2020 – 8th European Conference on Renewable Energy System on 24-25 August 2020 in Instanbul, Turkey. The accepted version of the publication may differ from the final published version.The aim of this paper is to present a fast and simple method for characterization and modelling of a PV module with due account taken of its application as a teaching tool for undergraduate courses. Thus, the paper presents a simplified mathematical analysis that underpins the modelling process of a PV module, which is based on the single-diode model (SDM). Subsequently, the paper explains a fast and straightforward method for extracting the parameters of the single-diode model from experimentally obtained I-V (current-voltage) characteristic of a PV module. The parameter extraction strategy uses a spreadsheet approach to solve the nonlinear equations of the model, which alleviates the need for any nonlinear equation solvers. The method was used, as a laboratory exercise for engineering students, to extract the parameters of a small monocrystalline silicon PV module and the results concurred well with the manufacturer’s datasheet and with experimental results. The differences were within the manufacturer’s specified tolerance of 10%

Performance evaluation of analytical methods for parameters extraction of photovoltaic generators

© 2020 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/en13184825This paper presents a succinct exploration of several analytical methods for extracting the parameters of the single-diode model (SDM) of a photovoltaic (PV) module under standard test conditions (STC). The paper investigates six methods and presents the detailed mathematical analysis leading to the development of each method. To evaluate the performance of these methods, MATLAB-based software has been devised and deployed to generate the results of each method when used to extract the SDM parameters of various PV test modules of different PV technologies. Similar software has also been developed to extract the same parameters using well-established numerical and iterative techniques. A comparison is subsequently made between the synthesized results and those obtained using numerical and iterative methods. The comparison indicates that although analytical methods may involve a significant amount of approximations, their accuracy can be comparable to that of their numerical and iterative counterparts, with the added advantage of a significant reduction in computational complexity, and without the initialization and convergence difficulties, which are normally associated with numerical methods.Published onlin

Adjusting the single-diode model parameters of a photovoltaic module with irradiance and temperature

�� 2020 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher���s website: https://doi.org/10.3390/en13123226This paper presents a concise discussion and an investigation of the most literature-reported methods for modifying the lumped-circuit parameters of the single-diode model (SDM) of a photovoltaic (PV) module, to suit the prevailing climatic conditions of irradiance and temperature. These parameters provide the designer of a PV system with an essential design and simulation tool to maximize the efficiency of the system. The parameter modification methods were tested using three commercially available PV modules of different PV technologies, namely monocrystalline, multicrystalline, and thin film types. The SDM parameters of the three test modules were extracted under standard test conditions (STC) using a well-established numerical technique. Using these STC parameters as reference values, the parameter adjustment methods were subsequently deployed to calculate the modified parameters of the SDM under various operating conditions of temperature and irradiance using MATLAB-based software. The accuracy and effectiveness of these methods were evaluated by a comparison between the calculated and measured values of the modified parameters.This research received no external funding.Published onlin

Variation of the performance of a PV panel with the number of bypass diodes and partial shading patterns

This paper presents an investigation into the variation of the performance of a PV module under different patterns of partial shading with variation in the number of bypass diodes. The investigation was performed using a MATLAB/Simulink simulation approach, which mitigates the need for complex numerical techniques. The single-diode model of a PV cell was used in the modelling. The performance is assessed in terms of the global maximum power yield and the number of local power peaks in the power-voltage characteristic of the PV module. Results indicate that increasing the number of bypass diodes can improve the energy yield of a module at the expense of increasing the number of local power peaks in the power-voltage curve. It is also found that the latter depends, not only on the pattern of partial shading, but also on its severity.Author accepted manuscrip

Effect of stoichiometry on AC and DC breakdown of silicon nitride/epoxy nanocomposites

This is an accepted manuscript of an article published by IEEE in IEEE Transactions on Dielectrics and Electrical Insulation on 17/08/2021. Available online https://doi.org/10.1109/TDEI.2021.009561 The accepted version of the publication may differ from the final published version.This study investigates the electrical behavior of silicon nitride/epoxy nanocomposites. It is demonstrated that the presence of the nanofiller affects the resin/hardener stoichiometry, which results in the development of different network structures throughout the matrix polymer. However, detailed analysis shows that this stoichiometric effect cannot account, alone, for the observed changes in the electrical behavior of the nanocomposite samples. A comparison between the electrical behavior of filled and the unfilled samples, where appropriate stoichiometric compensation has been applied, indicates that there is an additional effect that is exclusively a function of the nanofiller loading and which is superimposed on any matrix chemistry effects. Potential explanations for this nanoparticle effect are discussed, including: nanoparticle agglomeration; water shells around the nanoparticles; the influence of nanoparticles on matrix dynamics, structure or the free volume content of polymer interphase

Digital tanlock loop architecture with no delay

This article proposes a new architecture for a digital tanlock loop which eliminates the time-delay block. The �=2 (rad) phase shift relationship between the two channels, which is generated by the delay block in the conventional timedelay digital tanlock loop (TDTL), is preserved using two quadrature sampling signals for the loop channels. The proposed system outperformed the original TDTL architecture, when both systems were tested with frequency shift keying input signal. The new system demonstrated better linearity and acquisition speed as well as improved noise performance compared with the original TDTL architecture. Furthermore, the removal of the time-delay block enables all processing to be digitally performed, which reduces the implementation complexity. Both the original TDTL and the new architecture without the delay block were modelled and simulated using ATLAB/Simulink. Implementation issues, including complexity and relation to simulation of both architectures, are also addressed

Evaluation of analytical methods for parameter extraction of PV modules

© 2017 The Authors. Published by Elsevier Ltd. A review and evaluation of the main analytical techniques for parameters extraction of photovoltaic (PV) modules with due account taken of their applications in modelling photovoltaic systems is presented. Six prevalent analytical methods are investigated and assessed using software tools, which have been developed to extract the required parameters of some commercially available PV modules using these methods. The results were subsequently compared with those obtained using well-established numerical methods. It is shown that, despite the fact that analytical methods can involve a fair amount of approximations, some analytical methods can compete in terms of accuracy with their numerical counterparts with much reduced computational complexity. .Published versio

Synchronization of a renewable energy inverter with the grid

The design, mathematical analysis, and testing results of the architecture of a new all-digital phase-locked loop system for synchronizing a voltage source DC-AC single-phase inverter with the low voltage utility grid are presented. The system which is based on the time-delay digital tanlock loop was simulated using MATLAB/ SIMULINK and was tested by subjecting the grid voltage to various perturbations similar to those which can occur in a real power system, such as voltage sags and nonlinear distortion of the grid voltage waveform. Results indicate that even in the presence of such perturbations the system achieved and/or re-gained synchronization within 100 ms. The proposed system is all-digital and can be readily implemented using a field programmable gate array and easily embedded into a power inverter

A nonuniform DPLL architecture for optimized performance

This paper presents the design, analysis, simulation, and implementation of the architecture of a new nonuniform-type digital phase-locked loop (DPLL). The proposed loop uses a composite phase detector (CPD), which consists of a sample-and-hold unit and an arctan block. The CPD improves the system linearity and results in a wider lock range. In addition, the loop has an adaptive controller block, which can be used to minimize the overall system sensitivity to variations in the power of the input signal. Furthermore, the controller has a tuning mechanism that gives the designer the flexibility to customize the loop parameters to suit a particular application. These performance parameters include lock range, acquisition time, phase noise or jitter, and signal-to-noise ratio enhancement. The simulation results show that the proposed loop provides flexibility to optimize the major conflicting system parameters. A prototype of the proposed system was implemented using a field-programmable gate array (FPGA), and the practical results concur with those obtained by simulation using MATLAB/Simulink. © 2013 Institute of Electrical Engineers of Japan.Published versio