The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.

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Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques

This paper proposes a method of modeling and simulation of photovoltaic arrays. The main objective is to find the parameters of the nonlinear I-V equation by adjusting the curve at three points: open circuit, maximum power, and short circuit. Given these three points, which are provided by all commercial array data sheets, the method finds the best I-V equation for the single-diode photovoltaic (PV) model including the effect of the series and parallel resistances, and warranties that the maximum power of the model matches with the maximum power of the real array. With the parameters of the adjusted I-V equation, one can build a PV circuit model with any circuit simulator by using basic math blocks. The modeling method and the proposed circuit model are useful for power electronics designers who need a simple, fast, accurate, and easy-to-use modeling method for using in simulations of PV systems. In the first pages, the reader will find a tutorial on PV devices and will understand the parameters that compose the single-diode PV model. The modeling method is then introduced and presented in details. The model is validated with experimental data of commercial PV arrays.

Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays

Maximum power point tracking (MPPT) techniques are used in photovoltaic (PV) systems to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on panels temperature and on irradiance conditions. The issue of MPPT has been addressed in different ways in the literature but, especially for low-cost implementations, the perturb and observe (PO moreover, it is well known that the P&O algorithm can be confused during those time intervals characterized by rapidly changing atmospheric conditions. In this paper it is shown that, in order to limit the negative effects associated to the above drawbacks, the P&O MPPT parameters must be customized to the dynamic behavior of the specific converter adopted. A theoretical analysis allowing the optimal choice of such parameters is also carried out. Results of experimental measurements are in agreement with the predictions of theoretical analysis.

/pdf/optimization-of-perturb-and-observe-maximum-power-point-z7a8beok09.pdf

Optimization of perturb and observe maximum power point tracking method

Maximum power point tracking (MPPT) techniques are employed in photovoltaic (PV) systems to make full utilization of PV array output power which depends on solar irradiation and ambient temperature. Among all the MPPT strategies, the incremental conductance (INC) algorithm is widely used due to the high tracking accuracy at steady state and good adaptability to the rapidly changing atmospheric conditions. In this paper, a modified variable step size INC MPPT algorithm is proposed, which automatically adjusts the step size to track the PV array maximum power point. Compared with the conventional fixed step size method, the proposed approach can effectively improve the MPPT speed and accuracy simultaneously. Furthermore, it is simple and can be easily implemented in digital signal processors. A theoretical analysis and the design principle of the proposed method are provided and its feasibility is also verified by simulation and experimental results.

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A Variable Step Size INC MPPT Method for PV Systems

Review of the maximum power point tracking algorithms for stand-alone photovoltaic systems

As the maximum power operating point (MPOP) of photovoltaic (PV) power generation systems changes with changing atmospheric conditions (e.g. solar radiation and temperature), an important consideration in the design of efficient PV systems is to track the MPOP correctly. Many maximum power tracking (MPT) techniques have been considered in the past but techniques using microprocessors with appropriate MPT algorithms are favoured because of their flexibility and compatibility with different PV arrays. Although the efficiency of these MPT algorithms is usually high, it drops noticeably in cases of rapidly changing atmospheric conditions. The authors have developed a new MPT algorithm based on the fact that the MPOP of a PV generator can be tracked accurately by comparing the incremental and instantaneous conductances of the PV array. The work was carried out by both simulation and experiment, with results showing that the developed incremental conductance (IncCond) algorithm has successfully tracked the MPOP, even in cases of rapidly changing atmospheric conditions, and has higher efficiency than ordinary algorithms in terms of total PV energy transferred to the load.

Maximum photovoltaic power tracking: an algorithm for rapidly changing atmospheric conditions

HTS squirrel-cage induction motor was fabricated and tested in this study Both of rotor bars and end rings were made of Bi-2223/Ag multifilamentary tapes in order to realize superconducting current loops, and the conventional (normal conducting) stator, 3-phase and 4-pole, was utilized Rotating characteristics of the fabricated motor were tested for different input voltages at 60 Hz The performances were also analyzed by means of the theoretical method based on the electrical equivalent circuit It was shown that the minimum starting voltage was experimentally confirmed and agreed semi-quantitatively with the analysis result The rotation at synchronous speed was realized by applying the load, at least, 15 Nm

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Fabrication and Characteristics of HTS Induction Motor by the Use of Bi-2223/Ag Squirrel-Cage Rotor

A experiment of a DC Superconducting power transmission line using HTS conductor was started in Chubu University, Japan in autumn 2006. The first cooling down began in October 2006. The coolant is liquid nitrogen, and the cooling system used a cryogenic cooler and cold pump. The operation temperature is the range of 72 K - 80 K. The power cable has a total length of 20 m, and composed of thirty-nine Bi-2223 HTS tape conductors with critical current approximately100 A. The power cable achieved a 2.2 kA. The insulation voltage of the cable is 20 kV. In order to reduce the heat leakage and to avoid the current imbalance in the HTS tapes, we installed the Pelteir Current Lead (PCL) for each of the nineteen HTS tapes of the cable, with remaining twenty HTS tapes connected individually by the usual copper leads (CCL). Depending on the visual observation, and the measurement of temperatures of the current leads, the heat leakage of the PCL is lower than that of CCL. We installed a current transformer for each individual HTS tape conductor circuit, and measured the current of each HTS tape conductor. We measured the critical current of each HTS tape after the cable was installed into the cryostat, and degradation was not observed. Since the variation of the current in each tape is less than 10%, we eliminated the problem of current imbalance. Computational Fluid Dynamics is used to estimate the pressure drop, showing that the straight-tube cryostat has the advantage against the bellows- and corrugated-tube cryostats to reduce the pressure drop of the circulation of coolant. We proposed further to use the siphon for circulating the coolant in order to reduce the circulation losses and costs. We proposed that the voltage of the system be kept below 30 kV in order to use low cost power inverters. This choice can increase the storage energy of the power transmission line itself if we do not use a co-axial cable system because of it allows use of large current. And the magnetic energy of power grid is estimated to 4.5MJ/km for ±30 kA.

http://iopscience.iop.org/article/10.1088/1742-6596/97/1/012290/pdf

Research activities of DC superconducting power transmission line in Chubu University

Design and performance of compensator for decremental persistent current in HTS magnets using linear type magnetic flux pump

In high power applications, the fault current limiter has been discussed for many years because of some limitations of conventional circuit breakers. Many types of fault current limiter have already been introduced in papers. In this work, a simple bridge-type fault current limiter has been designed and constructed. The performances of the limiter have been tested successfully. In the bridge-type current limiter, a DC reactor appears in the line when the connected load is increasing. This causes a voltage drop across the load terminal during load changing. The DC reactor effect of the current limiter has been studied. Some experimental results regarding the reactor effect of the limiter have been considered and compared with the results obtained from computer simulation.

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Tsutomu Hoshino

Papers

Maximum photovoltaic power tracking: an algorithm for rapidly changing atmospheric conditions

Fabrication and Characteristics of HTS Induction Motor by the Use of Bi-2223/Ag Squirrel-Cage Rotor

Research activities of DC superconducting power transmission line in Chubu University

Design and performance of compensator for decremental persistent current in HTS magnets using linear type magnetic flux pump

DC reactor effect on bridge type superconducting fault current limiter during load increasing