Search

Direct grid coupling of permanent magnet synchronous generators (PMSG) for wind energy conversion systems provides certain advantages with the penalties of maximum power point tracking (MPPT) and reactive power control. This article proposes a novel PMSG design philosophy such that optimizing PMSG design at the initial stage would compensate for the drawbacks arising from the lack of an MPPT algorithm. Also, the ability to maintain a high PF across a wide range of operating power levels is investigated by considering reactive power in the design process. In this article, optimization of slot/pole combination is described for direct grid coupled PMSGs to extract as much energy as possible according to wind data. A new benchmark, adequacy factor, is presented to determine the slot/pole combination. Variation of the reactive power is theoretically analyzed. A relationship is established between induced electromotive force, synchronous inductance values of machines, and the PF. Fixed and variable speed operations of PMSGs are compared in terms of annual energy yield. Finally, theoretical analyses are validated through laboratory testing of prototype generators., Scientific and Technological Research Council of Turkey [117E785], This work was supported by The Scientific and Technological Research Council of Turkey under Grant 117E785.

The use of solar power in some applications is challenging due to sudden changes in irradiance level and the fast occurrence of Partial Shading Condition (PSC). For this reason, maximum power point tracking (MPPT) methods employed in photovoltaic (PV) applications allow for very fast detection and tracking of the maximum power point (MPP) during a partial shading condition. This fast reaction should minimize the power losses, have minimum steady-state oscillation and be accurate. In this paper, an analytical approach is proposed to track the real MPP in Uniform Irradiance Condition (UIC) and PSC via the use of analytical formulas of the PV system behavior. The proposed method exhibits a rapid tracking speed, stable steady-state performance, and low sampling rate in all conditions. The characteristics and performance of the proposed algorithm under UIC and PSC are investigated and demonstrated through simulations and experimental tests.

WOS: 000524097200032, This paper addresses an improved optimization method to enhance the energy extraction capability of fuel cell implementations. In this study, the proposed method called Dynamic Cuckoo Search Algorithm (DCSA) is tested in a stand-alone fuel cell in order to control the system power under dynamic temperature response. In the operational process, a fuel cell is connected to a load through a dc-dc boost converter, and DCSA is utilized to adjust the switching duration in dc-dc converter by using voltage, current and temperature parameters. In this way, it controls the output voltage to maximize power delivery capability at the demand-side and eliminates the drawback of conventional cuckoo search algorithm (CSA) which cannot change duty cycle under operating temperature variations. In this regard, DCSA shows a significant improvement in terms of system response and achieves a more efficient power extraction than the conventional CSA method. In order to demonstrate the system performance, the stand-alone fuel cell system is constructed in Simulink environment via a processor-in the-loop (PIL) based digital implementation and analyzed by using different optimization methods. In the analysis section, the results of the proposed method are compared with conventional methods (perturb&observe mppt, incremental conductance mppt, and particle swarm optimization). In this context, convergence speed and efficiency analysis for both methods verify that the DCSA gives original results compared to conventional methods. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

In this paper, the validation and performance testing of a control scheme for a single-phase single-stage transformerless grid-connected Photovoltaic (PV) inverter are presented using the Control-Hardware-in-the-Loop (C-HIL) implementation. The control scheme uses the DC-link voltage controller and grid current controller, and it is executed in a LAUNCHXL-F28379D development kit, providing a cost-effective solution compared to commercially available tools. In order to extract the maximum available power from the PV system under different conditions, two Maximum Power Point Tracking (MPPT) algorithms, including the Perturb and Observe (P&O) algorithm and incremental conductance method, are investigated and compared. The simulation and experimental results are provided to verify the performance of the studied control scheme.

The multiple power peaks obtained in the power-voltage (P-V) curve of a photovoltaic string under partially shaded condition results in a complicated maximum power point tracking (MPPT) process. Under this condition, the conventional MPPT methods are not acknowledged as they result in false and slow tracking. In this study three novel global MPPT (GMPPT) methods have been proposed and validated. These are named as large and small duty step (LSDS), large and mutable duty step (LMDS) and fast and intelligent GMPPT (FI-GMPPT). The LSDS method sweeps almost the entire P-V curve using a combination of LSDS. Small duty steps are used in predefined areas near all local maximum power points of the P-V curve. LMDS is a further improved method, which uses a combination of LMDSs. The FI-GMPPT is an advance true GMPPT method which limits the area to be swept during the search process. This results in a further reduction in sweep time. In this method, the unnecessary area is skipped during the sweep process. The improved performance of the projected methods has been demonstrated and validated using MATLAB/SIMULINK and hardware implementation. - The Institution of Engineering and Technology 2019 The support of the Council of Science and Technology Uttar Pradesh (CST/2732), India, for this work is highly acknowledged. Scopus

Made available in DSpace on 2018-12-11T16:55:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-08-30 Penetration rate of grid-connected photovoltaic (PV) generation to the existing utility grid is rapidly increasing over the years. Since the power generated from PV systems fluctuate according to the weather condition, e.g., cloud passing, this can significantly disturb the stability of a weak utility grid. The integration of energy storage devices and its ramp-rate control technique are required to reduce the impact of PV systems output fluctuations and augment the stability of the utility grid. In this paper, ramp-rate control is applied to the direct connection of energy storage devices in PV generation system configuration. The direct connection of supercapacitors string and battery combination scheme is proposed to reduce the number of power converters so that the efficiency of the system is increased. In this work, the PV system output is controlled by directly control the energy storage system (ESS) to limit the changing rate of PV output to desired ramp-rate value. Hence, reducing the battery charge/discharge cycles and extending the expected lifetime of the ESS. The performance of the proposed direct connection scheme of ESS and its ramp-rate control strategy is verified using a 1-kW PV system prototype. Electrical Engineering, Khalifa University of Science Technology and Research, 105955 Abu Dhabi, Abu Dhabi United Arab Emirates (e-mail: yoga.sandi@yahoo.com) Department of Electrical and Computer Engineering, Curtin University, 1649 Perth, Western Australia Australia 6845 (e-mail: s.m.muyeen@ieee.org) Electrical Engineering, Khalifa University of Science and Technology, Abu Dhabi United Arab Emirates (e-mail: ahmed.aldurra@ku.ac.ae) Electrical Engineering and Computer Science, Colorado School of Mines, Golden, Colorado United States 80401-1887 (e-mail: msimoes@mines.edu) Sao Paulo State University, Sao Paulo, Sorocaba Brazil (e-mail: helmo.paredes@unesp.br)

Wind energy conversion systems (WECSs) require a suitable control to maximise the power generated by wind turbines independently on the wind conditions. Variable-speed fixed-pitch wind turbines with doubly-fed induction generators (DGIG) are used in WECSs for their higher reliability and efficiency compared to variable-pitch wind turbine systems. This study proposes an effective control algorithm to maximise the efficiency of fixed-pitch wind turbines with DFIGs using particle swarm optimisation control to compensate for the errors in the estimation of the circuit parameters of the generator. The proposed control algorithm generates an optimal speed reference to optimise the mechanical power extracted from the wind and the optimal d-axis rotor current through stator reactive power management to minimise the electrical losses of the doubly-fed generator. The optimal speed reference is provided by a maximum power point tracking control below the rated wind speed and a soft-stalling control above the rated wind speed, while the optimal d-axis rotor current is searched by a particle swarm optimisation algorithm. The proposed control system has been verified by numerical simulations and it has been demonstrated that the energy generated for typical wind speed profiles is greater than that of a traditional control based on a model-based loss minimisation.

Wind energy is an important renewable source with a stochastic nature. To capture this energy, variable speed generators are installed in wind towers and different maximum power point (MPP) tracking (MPPT) strategies have been developed in literature to maximise the output power. However, in gusty weather, wind turbines fail to track the optimum operating point due to their relatively high inertia. This paper proposes an innovative MPPT strategy to capture the energy of wind gusts. The developed controller consists of a conventional TSR control together with a bidirectional controller, which takes over the control of the rectifier under varying wind condition. The simulation results show an overall efficiency improvement and more stability for the proposed strategy.

This paper proposes a maximum power point tracking (MPPT) method with partial shading (PS) detection based on modified PI incremental conductance (IC) for photovoltaic inverters. To accurately trigger the algorithm, a PS detecting approach based on voltage deviation is derived through the comparison of voltage and current characteristics under uniform and non-uniform insolation. To track the global maximum power point (GMPP) precisely and fast, a global search scheme considering appropriate voltage reference, search direction and termination criteria is presented. The modified PI-based IC method is implemented in the local search process. In order to verify the effectiveness of the algorithm, the proposed method is utilised in the two-stage grid-connected photovoltaic inverters built in MATLAB/Simulink. The performance of the scheme is compared with the traditional IC method under step-changing and gradual-changing insolation and various temperature. In all simulation cases, the proposed approach can identify the PS with multiple local maxima, accurately trigger the global search process and track the GMPP. The search periods are around 0.1–0.2 s, and the efficiencies of PV generation under steady state are normally above 99.5%. The presented method can improve the efficiency of distributed and centralised PV system.

An improved performance of a photovoltaic (PV) pumping system employing a synchronous reluctance motor (SynRM) under partial shading conditions is proposed. The system does not include the dc-dc converter that is predominantly being utilized for maximizing the output power of the PV array. In addition, storage batteries are also not contained. A conventional inverter connected directly to the PV array is used to drive the SynRM. Further, a control strategy is proposed to drive the inverter so that the maximum output power of the PV array is achieved while the SynRM is working at the maximum torque per Ampère condition. Consequently, this results in an improved system efficiency and cost. Moreover, two maximum power point tracking (MPPT) techniques are compared under uniform and partial shadow irradiation conditions. The first MPPT algorithm is based on the conventional perturbation and observation (P&O) method and the second one uses a differential evolution (DE) optimization technique. It is found that the DE optimization method leads to a higher PV output power than using the P&O method under the partial shadow condition. Hence, the pump flow rate is much higher. However, under a uniform irradiation level, the PV system provides the available maximum power using both MPPT techniques. The experimental measurements are obtained to validate the theoretical work.

Increasing the efficiency of photovoltaic (PV) systems is a pressing issue, and several studies have focused on the Maximum Power Point Tracking (MPPT) techniques to extract the maximum PV output power. Many MPPT techniques have been discussed in the last decade, and optimization-based MPPT techniques have shown better performance than other MPPT techniques. In this study, two optimization techniques, the cuckoo search algorithm and particle swa9rm optimization with changing inertia weight techniques are discussed and applied to a PV system to track the maximum power point. The MSX-60 PV module and boost DC-DC converter are used in this paper to simulate and model the MPPT system using MATLAB/Simulink to show which technique has the best performance under various solar irradiation scenarios. In addition, different structures of PV arrays such as series-parallel, bridge link, and total cross-tied PV structures are simulated to analyze their effect on the efficiency of MPPT processes.

The use of photovoltaic (PV) systems as electrical power generator is increasing rapidly and this growth is expected to be 2 continuous. As well known in PV systems the tracking of the maximum power point (MPP) is key. For this reason, many testing 3 systems and maximum power point tracking (MPPT) algorithms have been developed. Testing systems are used for system 4 development as well as for assessing the quality of PV products. The typical problem related to the evaluation of PV system 5 performances and MPPT algorithm comparison is the guarantee of the repeatability of the testing conditions (e.g. temperature and 6 radiation). 7In this paper, a testing system for PV applications has been developed and characterized. Flexibility, ease of use, low cost, 8 capability to evaluate the characteristic curves of more than one PV panel simultaneously (same environmental conditions), capability 9 of algorithms simulation, and capability of tracking MPP on the base of different MPPT algorithms are some of the main 10 characteristics. Experimental tests have been carried out to validate the performance of the developed architecture. In addition, 11 different MPPT algorithms have been compared in the same environmental conditions both in steady and dynamic state.

Modern PV arrays are generally designed with bypass diodes to avoid damage. However, such arrays exhibit multiple peaks in their P - V characteristics under partial shading conditions. Owing to the limitation in the abilities of conventional maximum power point tracking algorithms in such cases, the application of other optimisation algorithms has been explored. This study proposes a modified particle velocity-based particle swarm optimisation (MPV-PSO) algorithm for tracking the global power peak of the multiple peak P - V characteristics. The MPV-PSO algorithm is both adaptive and deterministic in nature. It eliminates the inherent randomness in the conventional PSO algorithm by excluding the use of random numbers in the velocity equation. The proposed algorithm also eliminates the need for tuning the weight factor, the cognitive and social acceleration coefficients by introducing adaptive values for them which adjust themselves based on the particle position. These adaptive values also solve problems like oscillations about the global best position during steady-state operation and particles getting trapped in local minima. The effectiveness of the proposed MPV-PSO algorithm is validated through MATLAB/Simulink simulations and hardware experiments.

The power versus voltage curves of solar photovoltaic panels form several peaks under fractional (partial) shading conditions. Traditional maximum output power tracking (MPPT) techniques fail to achieve global peak power at the output terminals. The proposed Cat Swarm Optimization (CSO) method intends to apply MPPT techniques to extract the global maxima from the shaded photovoltaic systems. CSO is a robust and powerful metaheuristic swarm-based optimization technique that has received very positive feedback since its emergence. It has been used to solve a variety of optimization issues, and several variations have been developed. The CSO-based maximum power tracking technique can successfully tackle two major issues of the PV system during shading conditions, including random oscillations caused by conventional tracking techniques and power loss. The proposed techniques have been extensively used in comparison to conventional algorithms like the Perturb and the Observe (P and O) technique. The main objective is to achieve a tracking speed for extracting the Maximum Power Point (MPP) from the solar Photovoltaic (PV) system under fractional shading conditions by using CSO. Modeling of the solar photovoltaic array in the MATLAB/Simulink platform comprises a photovoltaic module, a switching converter (Boost Converter), and the load. The PSO and CSO techniques are applied to the PV module under different weather conditions. The PSO algorithm is compared to the CSO algorithm according to simulation results, revealing that the CSO algorithm can provide better accuracy and a faster tracking speed.

This paper deals with an advanced design for a pump powered by solar energyto supply agricultural lands with water and also the maximum power point is used to extract the maximum value of the energy available inside the solar panels and comparing between techniques MPPT such as Incremental conductance, perturb & observe, fractional short current circuit, and fractional open voltage circuit to find the best technique among these. The solar system is designed with main parts: photovoltaic (PV) panel, direct current/direct current (DC/DC) converter, inverter, filter, and in addition, the battery is used to save energy in the event that there is an increased demand for energy and not to provide solar radiation, as well as saving energy in the case of generation more than demand. This work was done using the matrix laboratory (MATLAB) simulink program.

Photovoltaic (PV) system has a great potential and it is installed more when compared with other renewable energy sources nowadays. However, the PV system cannot perform optimally due to its solid reliance on climate conditions. Due to this dependency, PV system does not operate at its maximum power point (MPP). Many MPP tracking methods have been proposed for this purpose. One of these is the Perturb and Observe Method (P&O) which is the most famous due to its simplicity, less cost and fast track. But it deviates from MPP in continuously changing weather conditions, especially in rapidly changing irradiance conditions. A new Maximum Power Point Tracking (MPPT) method, Tetra Point Perturb and Observe (TPPO), has been proposed to improve PV system performance in changing irradiance conditions and the effects on characteristic curves of PV array module due to varying irradiance are delineated. The Proposed MPPT method has shown better results in increasing the efficiency of a PV system.

The conveyance of steel-plates is one of the potential uses of the magnetic levitation technology in industry. How¬ever, the electromagnetic levitation systems inherently show non¬linear feature and are unstable without an active control. Well-known U-shaped or E-shaped electromagnets cannot provide redundant levitation with multiple degrees of freedom. In this paper, to achieve the full redundant levitation of the steel plate, a quadruple configuration of U shaped electromagnets has been proposed. To resolve the issue of instability and attain more robust levitation, a centralized control algorithm based on a modified PID controller (I PD) is designed for each degree of freedom by using the Manabe canonical polynomial technique. The model of the system is carried out using electromechanical energy conversion princi¬ples and verified by 3-D FEM analysis. An experimental bench is built up to test the system performance under trajectory tracking and external disturbance excitation. The results confirm the effectiveness of the proposed system and the control approach to obtain a full redundant levitation even in case of disturbances. The paper demonstrates the feasibility of the con¬veyance of steel plates by using the quadruple configuration of U-shaped electromagnets and shows the merits of I-PD controller both in stabilization and increased robust levitation.

4th International Conference on Power Electronics and their Applications (ICPEA) -- SEP 25-27, 2019 -- Elazig, TURKEY, WOS: 000523476700044, In this paper, a transformer-less grid-connected PV system using low voltage panels is designed and analyzed for residential applications. For this, dual-level dc-dc boost converter is used to obtain a higher voltage level at the output, and the system is integrated into the utility-grids/loads through a three-phase inverter. By this way, the designed system reduces the cost and dimension in comparison with a conventional system. In the designed system, the switching operation of dual-level dc-dc converter is achieved using perturb & observe maximum power point tracking method. In the performance/analysis section, the system is tested for different load groups and irradiation levels. The results show that the system increases the PV voltage to the desired voltage value. Also, the system is analyzed for three irradiation levels and two local load groups. In case studies, it is obvious that the excess power is supplied to the grids and the lacking power is provided from the grids to feed loads., Ziane Achour Univ Djelfa, Firat Univ, Djelfa Univ, Fac Sci & Technol, Appl Automat & Ind Diagnost Lab, IEEE Algerian Sect, IEEE Turkey Sect, IEEE Power Elect Soc, IEEE Power & Energy Soc, IEEE Ind Applicat Soc, Djelfa Univ, IEEE, Firat Univ, Engn Fac

The performance optimization of photovoltaic panels in terms of energy production can be achieved by means of hardware and strategy control improvement. As well known the tracking algorithm deciding the working point of the system is key for the system efficiency. An algorithm category featuring good performance both in static and dynamic condition is that of model based maximum power point tracker. In this paper an optimization of the estimation of the model parameter is presented. The new estimation approach guarantees better performance in terms of energy generated by the modeled photovoltaic panel. Moreover, the estimation is more robust being less dependent on data measured in not optimal condition such as during partial shading.

A non-isolated high-voltage gain dual-input DC/DC converter with a zero voltage turn-off (ZVT) auxiliary circuit has been presented. Two photovoltaic (PV) modules can be connected to the proposed converter with separate maximum power point tracking (MPPT). The cost of whole PV power generation system can be decreased significantly as a single converter is employed instead of two converters. All switches can achieve ZVT by an auxiliary circuit, and turn-off switching losses can be decreased and the efficiency of the converter can be improved. Working principle and performance characteristics of the proposed converter are analysed in detail, a dual-input maximum power point tracking control algorithm has been designed for the proposed converter. An 800 W experimental prototype has been built to verify the theoretical analysis.

This work presents an extended study of the work published in the magazine INCISCOS 2018 titled “Improving of the Photovoltaic High Power Plant Generation Using DC/DC Micro Converters”, and intented to increase the amount of electrical energy generation of a Photovoltaic Plant located in Salinas, Imbabura Province, Ecuador through the implementation of DC/DC converters in the solar panel arrays and tracking techniques of the maximum power point. The results show that the insertion of the DC/DC converters in the system causes an increase in the amount of active power. The system is analiced in variation of solar radiation or changes in the ambient temperature as well., Este trabajo presenta un estudio amplio del trabajo publicado en la revista INCISCOS 2018 títulado “Improving of the Photovoltaic High Power Plant Generation Using DC/DC Micro Converters”;está enfocado en incrementar la cantidad de energía eléctrica generada de una Planta Fotovoltaica ubicada en Salinas, provincia de Imbabura-Ecuador, mediante la inclusión de micro convertidores DC/DC en los arreglos de los paneles fotovoltaicos y a partir de la implementación de una adecuada técnica de seguimiento del punto de máxima potencia. Los resultados indican que la inserción de los convertidores DC/DC en el sistema provocan un aumento en la cantidad de energía activa. Se realiza el análisis tanto con variaciones de la radiación solar como cambios en la temperatura ambiente.

Differential-mode inverter topologies are promising for renewable energy generation since they offer advantages such as passive elements sizes reduction, having decreased power losses and reduced total cost. Single phase buck-boost differential-mode current-source inverters (DMCSIs) can deliver wider range of output voltage above or below the input dc voltage, which is necessary for high-efficiency modern renewable energy applications. Since these inverters have continuous input currents, they are suitable for maximum power point tracking (MPPT) operation of photovoltaic systems. Yet, the investigation, operation and implementation of these types of inverters have not been extensively discussed. As a drawback, the total dc side input current of a single-phase inverter consists of a dc component and an undesirable ac component. This ac component frequency is double the output voltage frequency and thus it affects MPPT resulting in reduced total efficiency. In this study, five promising DMCSIs are proposed and compared in terms of their total efficiencies, high-frequency ripple current in the dc side, total harmonic distortion, devices sizes and ratings. Moreover, the sliding mode controller's design and possible methods of eliminating the input second harmonic current are discussed. 2.5 kW bidirectional inverters are implemented to confirm the design flexibility of the proposed DMCSIs. Scopus

As research and development of renewable and clean energy based systems is advancing rapidly, the nonlinear source emulator (NSE) is becoming very essential for testing of maximum power point trackers or downstream converters. Renewable and clean energy sources play important roles in both terrestrial and nonterrestrial applications. However, most existing NSEs have only been concerned with simulating energy sources in terrestrial applications, which may not be fast enough for testing of nonterrestrial applications. In this paper, a high-bandwidth NSE is developed that is able to simulate the behaviors of a typical nonlinear source under different critical conditions that can happen during their operations. The proposed 200-W NSE, which consists of a fourth-order output filter buck converter and a novel nonlinear small-signal reference generator, can quickly react not only to an instantaneous change in the input source but also to a load step between nominal and open circuit. Moreover, all of these operation modes have a very fast settling time of only 10 $\mu$ s, which is hundreds of times faster than that of existing works. This attribute allows for higher speed and a more efficient maximum power point tracking algorithm. The proposed NSE, therefore, offers a superior dynamic performance among devices of the same kind.

Solar photovoltaic (PV) arrays formed by series combination of several PV modules suffer from considerable reduction in power yield when subjected to mismatched operating conditions. To address this issue several schemes have been reported in the literature. Amongst these schemes, the distributed maximum power point tracking (DMPPT) schemes seem to be the most promising ones. However, majority of the existing DMPPT schemes employ voltage-equalisation technique, which cannot attain exact MPP for all the modules. To overcome this problem individual power measurement units are employed for each of the module but then it leads to the involvement of large number of sensors. Schemes which do not require modular level sensing have also been reported but they require to employ a very computational intensive control algorithm coupled with the need for precise communication. This study attempts to address these limitations by proposing a simpler DMPPT strategy. It requires only one conventional MPPT algorithm to extract maximum power from the overall system. The implementation of the scheme is carried out by utilising the power circuit configuration of the existing flyback-converter based standard DMPPT scheme. The viability of the scheme is ascertained through detailed simulation and experimental studies.

In this paper, an interconnection and damping assignment passivity-based control (IDA-PBC) theory is employed to obtain maximum power point tracking (MPPT) for a photovoltaic (PV) module. A current control mode is selected to obtain the general control law, which guarantees exponential stability of the system in the sense of Lyapunov. The current is selected as the objective of control in this paper, due to the variations of irradiance and temperature on the PV module to produce the most impact in the current provided by the panel in comparison with its voltage profile. A modification of the classical IDA-PBC theory is employed to control the dynamical system under trajectory tracking. Simulation results show the capacity of the proposed control to extract the maximum power from the PV module under high changes in the irradiance and temperature. All simulations are conducted in MATLAB/Simulink. © 2018 IEEE. Departamento Administrativo de Ciencia, Tecnología e Innovación, COLCIENCIAS: 727 2015 Department of Science, Information Technology and Innovation, Queensland Government ACKNOWLEDGMENTS The authors want to thanks to the National Scholarship Program Doctorates of the Administrative Department of Science, Technology and Innovation of Colombia (COLCIENCIAS), by calling 727 2015 and Ph.D program in Engineering of the TechnologicalUniversity of Pereira, and the Instituto Tec-nológico Metropolitano under the research project P-17211.

The maximum power point tracking (MPPT) is generally implemented in grid-connected photovoltaic (PV) power plants to maximize the energy yield. However, as the penetration level increases, challenging issues such as overloading and overvoltage arise in PV applications. Accordingly, a constant power generation (CPG) operation, in which the PV output power is limited to a specific value, has been imposed by some grid regulators to alleviate the integration challenges. In that case, the combined operation of MPPT and CPG is required, which increases the complexity of the controller design. To generalize the two control objectives, a flexible active power control algorithm that combines both MPPT and CPG operating modes is proposed. The proposed algorithm can optimize the performance in both modes (i.e., MPPT and CPG). By adjusting the voltage-step between two consecutive operating points, fast dynamics and low-power oscillations can be obtained. The performance of the proposed strategy is evaluated through simulations and experiments under different irradiance and power reference profiles. Accepted version

This paper presents an approach to control a grid-connected, five-level, diode-clamped converter (DCC) with solar arrays directly connected to each capacitor of the dc-link, On one hand, the control of such converters is challenging as the voltage imbalance among the capacitor may affect the power controller. On the other hand, when dealing with solar arrays, the dc voltage is a key point considering that the efficiency of the array highly depends on it. This article presents a solution where both aims are fulfilled: the desired capacitor voltages, set by the maximum power point tracking (MPPT) algorithm, are reached at the same time that these values are taken into account in the power controller. This is an unusual approach for five-level DCC that avoids the use of DC-DC stages, therefore it makes the system more affordable and avoids extra losses. Thanks to the capacitor voltage controller, proper power extraction from each solar array is achieved. The theoretical presentation of this approach is shown along with simulation results that validates its effectiveness. MINECO-FEDER

In this paper, the use of the Dual Kalman Filter for the identification of photovoltaic system parameters is presented. The system includes the photovoltaic source, the dc/dc converter and the battery/dc bus and both its states and parameters in the actual operating conditions are identified. In particular, the proposed approach gives the confidence interval for the system settling time, which is used for the real-time optimization of the perturbative maximum power point tracking algorithm. The proposed technique is implemented by using a Field-Programmable Gate Array and it is validated by means of both simulation and experimental results.

This study proposed an adaptive double-integral-sliding-mode-controller-maximum-power-point tracker (DISMC-MPPT) for maximum-power-point (MPP) tracking of a photovoltaic (PV) system. The objective of this study is to design a DISMC-MPPT with a new adaptive double-integral-sliding surface in order that MPP tracking is achieved with reduced chattering and steady-state error in the output voltage or current. The proposed adaptive DISMC-MPPT possesses a very simple and efficient PWM-based control structure that keeps switching frequency constant. The controller is designed considering the reaching and stability conditions to provide robustness and stability. The performance of the proposed adaptive DISMC-MPPT is verified through both MATLAB/Simulink simulation and experiment using a 0.2 kW prototype PV system. From the obtained results, it is found out that this DISMC-MPPT is found to be more efficient compared with that of Tan's and Jiao's DISMC-MPPTs.

Photovoltaic (PV) energy production has become more and more important in the latest years. The need of energy efficiency pushed the research in this field both on material innovation and system management. As well known, an essential task in a PV system is performed by the tracking algorithm that has to assure the maximum power generation of the system. Many Maximum Power Point Tracking (MPPT) techniques have been defined. Among them a very promising category is that based on the modeling of the panel (model-based MPPTs). This technique allows to achieve performance comparable to that of traditional algorithms in steady state conditions. On the other side it features much higher performance from a dynamic point of view. An issue of MB-MPPTs is related to the model parameter identification and in particular to the stability of the model fitting over time. In this paper this stability problem will be analyzed for a MPPT previously proposed by the authors.

WOS: 000393785200006 This study presents two-stage inverter topology for single-phase grid-connected photovoltaic (PV) applications and its control implementations. The two-stage systems are reliable and work well. Typically, the second stage inverts solar power into AC power, whereas the first stage which is used to increase low PV panel voltage can achieve maximum power point tracking. In this configuration, a boost or a flyback type DC/DC converter topology is usually employed. However, such converters have major drawbacks such as low efficiency and limited voltage gain due to power losses. In the proposed topology, a low-voltage PV panel can be connected to power grid through solar inverter by using high-gain DC/DC converter which has unique features such as galvanic isolation and continuous current for AC module applications. Conventional controller results in poor control performance due to the finite gain at desired frequencies. Hence, a plug-in repetitive controller is proposed to obtain low total harmonic distortions (THDs). The performance of the proposed system is provided for the system which injects the PV panel current in the maximum power point voltage to a grid of 220 V-(rms) at a power range of 150-300 W with a unity power factor and a low input current THD. Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) This work supported by Scientific and Technological Research Council of Turkey (TUBITAK) has been conducted in the Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC) in Department of Electrical and Computer Engineering at University of Wisconsin-Madison in USA. Author acknowledges TUBITAK for the support.

International audience; This paper describes the modeling and control of Permanent Magnet Synchronous Generator (PMSG) of 5MW for wind farms applications. The generators are linked to the grid by means of a fully controlled frequency converter, which consists of two three phase rectifiers, an intermediate DC-bus, and an inverter. The full system is connected to AC grid with phase to phase RMS voltage of 20kV. Proposed control strategies include the Maximum Power Point Tracking (MPPT) for the PMSG speed control, the active/reactive power control, and the DC-bus voltage management. To show the performances of the control strategies, some simulation results are presented and analyzed using Matlab/Simulink software.

International audience; This paper mainly focuses on model of photovoltaic cell for energy harvesting application (EHV). This model is developed using the standard simulation software LTspice to explore the effect of electrical and physical parameters on Current-Voltage (I-V) and Power-Voltage (P-V) characteristics of photovoltaic cell (PV). The proposed model is based on mathematical equations and is described through an equivalent circuit. The developed model serves to specify the optimal conditions for operating the PV cell and define the maximum power point (MPP). It also allows the prediction of PV cell behavior as a function of temperature and ambient radiation. To demonstrate the validity of the generated model, an experimental test was performed for a PV cell (of type“ASI” from SCHOTT Company). Experimental and technical data display a good agreement with the simulated findings.

International audience; This paper presents the control strategies of an offshore wind energy system based on 5MW Doubly Fed Induction Generator (DFIG). The DFIG seems to be interesting for such high power wind generator systems. The proposed control strategies include the Maximum Power Tracking (MPPT) for the DFIG speed control, the active/reactive power control, and the DC-bus voltage control method. To show the performances of the control strategies, some simulation results are presented and analyzed using Matlab/Simulink software.

Long-term acquisition of solar panel performance parameters, for panels operated at maximum power point in their real environment, is of critical importance in the photovoltaic research sector. However, few options exist for the characterization of non-standard panels such as concentrated photovoltaic systems, heavily soiled or shaded panels or those operating under non-standard spectral illumination; certainly, it is difficult to find such a measurement system that is flexible and affordable enough to be adopted by the smaller research institutes or universities. We present here an instrument aiming to fill this gap, autonomously tracking and maintaining any solar panel at maximum power point while continuously monitoring its operational parameters and dissipating the produced energy without connection to the power grid. The instrument allows periodic acquisition of current-voltage curves to verify the employed maximum power point tracking approach. At the same time, with hardware schematics and software code being provided, it provides a flexible open development environment for the monitoring of non-standard generators like concentrator photovoltaic systems and to test novel power tracking approaches. The key issues, and the corresponding solutions, encountered in the design are analyzed in detail and the relevant schematics presented.

Differential-mode buck-boost inverters have merits such as reduced switch number, ability to provide voltages higher or lower than the input voltage magnitude, improved efficiency, reduced cost and size, and increased power density, especially in low-power applications. There are five buck-boost inverters that can provide flexible output voltage without the need of a large electrolytic input side capacitor, which degrades the reliability of inverters. The continuous input current of these inverters is appropriate for maximum power point tracking operation in photovoltaic and fuel cells applications. Three of the five inverters can be isolated with high-frequency-link transformers where the common-mode leakage current can be mitigated. However, the performance and control of such converters have not been discussed in detail. In this paper, the five possible single-stage three-phase differential-mode buck-boost inverters with continuous input current are investigated and compared in terms of total losses, maximum ripple current, total harmonic distortion, and device and passive element ratings. In addition, the possible methods are presented for eliminating the input third-order harmonic current, resulting from the stored energy in the passive elements, as well as the output second-order harmonic currents. The ability for isolating the input and output sides of the inverters with a small-high frequency transformers is discussed. A changeable-terminal 2.5-kW bidirectional inverter is used to validate the design flexibility of the inverter topologies, when digital signal processor-controlled. NPRP Grant NPRP 4-250-2-080 from the Qatar National Research Fund (a member of Qatar Foundation). Scopus

Harvesting energy from ambient energy sources, such as thermal gradients is one solution to address the dramatic increase in energy consumption of personal electronics. While in the field, energy abundantly available in form of heat. The use of primary cells set to the competition a dramatic cost challenge. In principle the Bi2Te3 is a mature material for harvesting thermal energy, but challenge the community with a low voltage cold-start requirement. In this brief, a fully integrated, low voltage self-oscillating inductive converter driver was demonstrated as a cold-start function suited for circuit grazing the limits of thermodynamics voltage.