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Showing papers on "Maximum power point tracking published in 2002"


Journal ArticleDOI
TL;DR: In this article, a microprocessor-controlled tracker capable of online voltage and current measurements and programmed with both voltage-based and current-based MPPT algorithms is constructed, where the load of the solar system is either a water pump or a resistance.
Abstract: Detailed theoretical and experimental analyses are presented for the comparison of two simple fast and reliable maximum power point tracking (MPPT) techniques for photovoltaic systems (PV): the voltage-based (VMPPT) and the current-based (CMPPT) approaches. A microprocessor-controlled tracker capable of online voltage and current measurements and programmed with both VMPPT and CMPPT algorithms is constructed. The load of the solar system is either a water pump or a resistance. Simulink facilities are used for simulation and modeling of the novel trackers. The main advantage of this new MPPT, as compared with present trackers, is the elimination of reference (dummy) cells, which results in a more efficient, less expensive, and more reliable PV system.

761 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed an adaptive MPPT algorithm for photovoltaic (PV) power generation systems based on a short-current pulse of the PV to determine an optimum operating current where the maximum output power can be obtained and completely differs from conventional hill-climbing-based methods.
Abstract: This paper proposes a novel maximum-power-point tracking (MPPT) method with a simple algorithm for photovoltaic (PV) power generation systems. The method is based on use of a short-current pulse of the PV to determine an optimum operating current where the maximum output power can be obtained and completely differs from conventional hill-climbing-based methods. In the proposed system, the optimum operating current is instantaneously determined simply by taking a product of the short-current pulse amplitude and a parameter k because the optimum operating current is exactly proportional to the short current under various conditions of illuminance and temperature. Also, the system offers an identification capability of k by means of fast power-versus-current curve scanning, which makes the short-current pulse-based MPPT method adaptive to disturbances such as shades partially covering the PV panels and surface contamination. The above adaptive MPPT algorithm has been introduced into a current-controlled boost chopper and a multiple power converter system composed of PV-and-chopper modules. Various operating characteristics have experimentally been examined on this multiple PV-and-chopper module system from a practical viewpoint and excellent MPPT performance has been confirmed through the tests.

642 citations


Journal ArticleDOI
TL;DR: In this article, the authors present test results on hybrid solar systems, consisting of photovoltaic modules and thermal collectors (hybrid PV/T systems), and show that PV cooling can increase the electrical efficiency of PV modules, increasing the total efficiency of the systems.

535 citations



Proceedings ArticleDOI
07 Nov 2002
TL;DR: In this article, the authors show that a "converter-per-module" approach offers many advantages including individual module maximum power point tracking, which gives great flexibility in module layout, replacement, and insensitivity to shading; better protection of PV sources, and redundancy in the case of source or converter failure.
Abstract: New residential scale photovoltaic (PV) arrays are commonly connected to the grid by a single DC-AC inverter connected to a series string of PV modules, or many small DC-AC inverters which connect one or two modules directly to the AC grid. This paper shows that a "converter-per-module" approach offers many advantages including individual module maximum power point tracking, which gives great flexibility in module layout, replacement, and insensitivity to shading; better protection of PV sources, and redundancy in the case of source or converter failure; easier and safer installation and maintenance; and better data gathering. Simple nonisolated per-module DC-DC converters can be series connected to create a high voltage string connected to a simplified DC-AC inverter. These advantages are available without the cost or efficiency penalties of individual DC-AC grid connected inverters. Buck, boost, buck-boost and Cuk converters are possible cascadable converters. The boost converter is best if a significant step up is required, such as with a short string of 12 PV modules. A string of buck converters requires many more modules, but can always deliver any combination of module power. The buck converter is the most efficient topology for a given cost. While flexible in voltage ranges, buck-boost and Cuk converters are always at an efficiency or alternatively cost disadvantage.

310 citations


Book
01 Jan 2002
TL;DR: Introduction to Photovoltaic Systems and Pspice Spectral Response and Short Circuit Current Electrical Characteristics of the Solar Cell Solar Cell Arrays PV Modules and PV Generators Interfacing PV modules to Loads and Battery Modelling.
Abstract: Introduction to Photovoltaic Systems and Pspice Spectral Response and Short Circuit Current Electrical Characteristics of the Solar Cell Solar Cell Arrays PV Modules and PV Generators Interfacing PV Modules to Loads and Battery Modelling Power Conditioning and Inverter Modelling Stand -- Alone PV Systems Grid Connected PV Systems Small Photovoltaics

300 citations


Proceedings ArticleDOI
10 Dec 2002
TL;DR: In this article, a novel three-point weight comparison method was developed to avoid the oscillation problem of the perturbation and observation algorithm which is often employed to track the maximum power point.
Abstract: The electric power supplied by a photovoltaic power generation system depends on the solar radiation and temperature. Designing efficient PV systems heavily emphasizes tracking the maximum power operating point. This work develops a novel three-point weight comparison method that avoids the oscillation problem of the perturbation and observation algorithm which is often employed to track the maximum power point. Furthermore, a low cost control unit is developed, based on a single chip to adjust the output voltage of the solar cell array. Finally, experimental results confirm the superior performance of the proposed method.

259 citations


Proceedings ArticleDOI
10 Dec 2002
TL;DR: In this article, the authors focus on the latest development of inverters for photovoltaic AC-modules and propose a plug-and-play concept for the AC-module, which can provide a modular design and a flexible behavior in various grid conditions.
Abstract: This review-paper focuses on the latest development of inverters for photovoltaic AC-modules. The power range for these inverters is usually within 90 Watt to 500 Watt, which covers the most commercial photovoltaic-modules. Self-commutated inverters have replaced the grid-commutated ones. The same is true for the bulky low-frequency transformers versus the high-frequency transformers, which are used to adapt the voltage level. The AC-module provides a modular design and a flexible behaviour in various grid conditions. It hereby opens the market for photovoltaic-power for everyone at a low cost due to the plug and play concept, which also makes a further enlargement of the system possible.

251 citations


Journal ArticleDOI
TL;DR: In this article, an MP point tracking algorithm is developed using only SCA voltage information thus leading to current sensorless tracking control, which results in low ripple content, which improves the array performance and hence a lower value of capacitance is sufficient on the solar array side.
Abstract: Photovoltaic (PV) generators exhibit nonlinear v-i characteristics and maximum power (MP) points that vary with solar insulation. An intermediate converter can therefore increase efficiency by matching the PV system to the load and by operating the solar cell arrays (SCAs) at their maximum power point. An MP point tracking algorithm is developed using only SCA voltage information thus leading to current sensorless tracking control. The inadequacy of a boost converter for array voltage based MP point control is experimentally verified and an improved converter system is proposed. The proposed converter system results in low ripple content, which improves the array performance and hence a lower value of capacitance is sufficient on the solar array side. Simplified mathematical expressions for a PV source are derived. A signal flow graph is employed for modeling the converter system. Current sensorless peak power tracking effectiveness is demonstrated through simulation results. Experimental results are presented to validate the proposed method.

217 citations


Patent
07 Mar 2002
TL;DR: In this paper, the output current value of a direct-current power source obtained by low-frequency, minute modulation of the input voltage of a switching converter is detected in a circuit having an amplification factor switching function that switches the amplification factor between definite magnitudes synchronizing with the modulation.
Abstract: The output current value of a direct-current power source obtained by low-frequency, minute modulation of the input voltage of a switching converter is detected in a circuit having an amplification factor switching function that switches the amplification factor between definite magnitudes synchronizing with the modulation, and by using a signal obtained by demodulating in a discriminator circuit the output of this circuit synchronizing with the modulation to control the switching converter, the power point of the switching converter can be tracked to the maximum power point by following the change in state of the direct current power source.

212 citations


Proceedings ArticleDOI
19 May 2002
TL;DR: A novel two-mode MPPT control algorithm combining the constant voltage control and IncCond method is proposed to improve efficiency of the 3 kW PV power generation system at different insolation conditions.
Abstract: As is well-known, the maximum power point (MPP) of PV power generation system depends on array temperature and solar insolation, it is necessary to track MPP of solar array all the time. For the past years, many researches have been focused on various MPP control algorithms to draw the maximum power of the solar array. Among them, the constant voltage control method, the perturbation and observation (P&O) method and the incremental conductance method (IncCond) have drawn many attractions due to the usefulness of each system. In this paper, the effectiveness of the three different control algorithms are thoroughly investigated via simulations and proposed efficiency evaluation method on experiment. Both the steady-state and transient characteristics of each control algorithm along with measured efficiency are analyzed, respectively. Finally, a novel two-mode MPPT control algorithm combining the constant voltage control and IncCond method is proposed to improve efficiency of the 3 kW PV power generation system at different insolation conditions.

Proceedings ArticleDOI
07 Nov 2002
TL;DR: In this paper, a flyback-type utility interactive inverter is proposed for photovoltaic (PV) power generation systems, which allows stable AC current injection into the utility line without AC current sharing control.
Abstract: In recent years, interest in natural energy has grown because of increased environmental concerns. Many kinds of inverter circuits and their control schemes for photovoltaic (PV) power generation systems have been studied. In a conventional system, the PV array in which many PV modules are connected in series is used to obtain sufficient DC-bus voltage for generating an AC utility line voltage from an inverter circuit. However, the total power generation of the PV array is sometimes decreased remarkably when a few modules are partially covered by shadows, thereby decreasing its inherent current generation, and preventing the generation current attaining its maximum value on the array. To overcome this drawback, an AC module strategy has been proposed. In this system, a small power DC-AC utility interactive inverter is mounted on each PV module individually. This inverter operates so as to generate the maximum power from its corresponding PV module. This paper proposes a novel flyback-type utility interactive inverter circuit suitable for AC module systems. The features of the proposed system are that it: (1) is small in volume and lightweight; (2) allows stable AC current injection into the utility line; (3) enables the stable parallel operation without AC current sharing control; and (4) enables the capacitance of the DC capacitor to be small. The effectiveness of the proposed system is clarified through simulation and experiments.

Journal ArticleDOI
TL;DR: In this article, a novel technique for efficiently extracting maximum power from photovoltaic (PV) panels is presented, which is based on injecting a small-signal sinusoidal perturbation into the switching frequency and comparing the AC component and the average value of the panel terminal voltage.
Abstract: A novel technique for efficiently extracting maximum power from photovoltaic (PV) panels is presented. The power conversion stage, which is connected between a PV panel and a load or bus, is a SEPIC or Cuk converter or their derived circuits operating in discontinuous inductor-current or capacitor-voltage mode. A method of locating the maximum power point (MPP) is based on injecting a small-signal sinusoidal perturbation into the switching frequency and comparing the AC component and the average value of the panel terminal voltage. Apart from not requiring any sophisticated digital computation of the panel power, the proposed technique does not approximate the panel characteristics and can globally locate the MPP under wide insolation conditions. The tracking capability has been verified experimentally with a 10 W solar panel under a controlled experimental setup. Performances under the steady state and in the large-signal change of the insolation level will are given.

Patent
26 Sep 2002
TL;DR: In this paper, a first AC power source comprising a fuel cell power plant and a second power source, typically grid, are normally connected via a high speed isolation switching means to provide sufficient AC power to a critical load.
Abstract: A first AC power source comprising a fuel cell power plant (18), and a second power source, typically grid (10), are normally connected via a high speed isolation switching means (19) to provide sufficient AC power to a critical load (14).

Journal ArticleDOI
TL;DR: In this paper, a hybrid photovoltaic (PV)-fuel cell generation system employing an electrolyzer for hydrogen generation is designed and simulated and applied for remote areas or isolated loads.

Patent
30 Aug 2002
TL;DR: In this paper, a photovoltaic power generation system consisting of storage batteries for storing electric power and a switch control device for switching to output electric power from the solar cell device to the storage batteries or the inverter is presented.
Abstract: An object of the present invention is to provide a system capable of reducing optimally peak demand for power by using small capacity storage batteries. The present invention was made to provide a photovoltaic power generation system which links with a utility power system, feeds electric power generated by a solar cell device to an inverter in order to convert the electric power into alternating current, and supplies the alternating current to a power consumption section. The photovoltaic power generation system comprises storage batteries for storing electric power and a switch control device for switching to output electric power from the solar cell device to the storage batteries or the inverter. Also the photovoltaic power generation system controls discharge of the electric power stored in the storage batteries with reference to a specific period of high power demand represented by a fluctuation curve of power demand, and supplies the electric power from the storage batteries along with generation power from the solar cell device to the inverter.

Journal ArticleDOI
TL;DR: In this article, a feed forward maximum power (MP) point tracking scheme was developed for the interleaved dual boost (IDB) converter fed photovoltaic (PV) system using fuzzy controller.
Abstract: A feedforward maximum power (MP) point tracking scheme is developed for the interleaved dual boost (IDB) converter fed photovoltaic (PV) system using fuzzy controller. The tracking algorithm changes the duty ratio of the converter such that the solar cell array (SCA) voltage equals the voltage corresponding to the MP point at that solar insolation. This is done by the feedforward loop, which generates an error signal by comparing the instantaneous array voltage and reference voltage. The reference voltage for the feedforward loop, corresponding to the MP point, is obtained by an off-line trained neural network. Experimental data is used for off-line training of the neural network, which employs back-propagation algorithm. The proposed fuzzy feedforward peak power tracking effectiveness is demonstrated through the simulation and experimental results, and compared with the conventional proportional plus integral (PI) controller based system. Finally, a comparative study of interleaved boost and conventional boost converter for the PV applications is given and their suitability is discussed.

Proceedings ArticleDOI
07 Aug 2002
TL;DR: In this article, a photovoltaic energy system, controlled by a DC-DC converter and a single phase bi-directional PWM converter to realize the inversion, is introduced.
Abstract: This paper introduces a photovoltaic energy system, controlled by a DC-DC converter and a single phase bi-directional PWM converter to realize the inversion. A current controlling (MPPT) method of tracking the maximum power point and forcing the system to operate close to this point is used. An artificial neural network is used in the MPPT system and its robustness and insensitivity to the intermittent weather conditions is enhanced. Uc3854 is used as an inversion current controller, which has a high performance in harmonics and power factor.

Journal ArticleDOI
TL;DR: This new proposal combines the advantages of the static phase-shifter and chain-cell converter concept and operates as a high-power digital-to-analog converter with 31-level resolution for uninterruptible power supply and flexible AC transmission applications.
Abstract: Power inverter modules fed with separate DC voltage sources of voltage ratio 1:2:4:8 are connected to form a cascade multilevel inverter. This new proposal combines the advantages of the static phase-shifter and chain-cell converter concept. Using the same number of power devices as a standard nine-level inverter, the proposed converter operates as a high-power digital-to-analog converter with 31-level resolution. Electrolytic capacitors used in the proposed inverter for providing the DC voltage sources will never be connected in opposite polarity in all cases, thus ensuring high reliability. The proposal has the potential for uninterruptible power supply and flexible AC transmission applications.

Proceedings ArticleDOI
07 Aug 2002
TL;DR: The maximum power point tracking control is based on adaptive fuzzy logic to control MOSFET switch of boost converter and single phase inverter uses predicted current control to control four IGBTs switch for grid-connected control.
Abstract: In this paper proposed method of maximum power point tracking using adaptive fuzzy logic control for grid connected photovoltaic system. The system composed of boost converter single-phase inverter connected to utility grid. The maximum power point tracking control is based on adaptive fuzzy logic to control MOSFET switch of boost converter and single phase inverter uses predicted current control to control four IGBTs switch for grid-connected control. Adaptive fuzzy logic controllers provide attractive features such as fast response, good performance and it can also change fuzzy parameter for improving control system. The fuzzy logic predicted current control provide current with sinusoidal waveshape and inphase with voltage. This system can provide energy with low harmonics and high power factor.

Proceedings ArticleDOI
07 Aug 2002
TL;DR: Using the maximum-efficiency control and themaximum-torque control, the losses of IPMSG are minimized and as a result the maximum generated power is obtained.
Abstract: This paper presents the optimum control of an interior permanent magnet synchronous generator (IPMSG) for a wind generation system. In order to maximize a generated power, IPMSG is controlled by a maximum power point tracking (MPPT) control and a maximum efficiency control. The torque of IPMSG is suitably controlled according to a generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control without a wind speed detector. Moreover, using the maximum-efficiency control and the maximum-torque control, the losses of IPMSG are minimized and as a result the maximum generated power is obtained. Experimental results show the effectiveness of the proposed control method.

Proceedings ArticleDOI
07 Nov 2002
TL;DR: In this paper, a new maximum power point tracking (MPPT) method for a photovoltaic (PV) power generation system was studied which can efficiently generate PV power even under changing weather conditions.
Abstract: A new maximum-power-point-tracking (MPPT) method for a photovoltaic (PV) power generation system was studied which can efficiently generate PV power even under changing weather conditions. In order to research a method suitable for the actual photovoltaic power system, PV characteristics of the maximum power point were measured for more than six months using a PV curve tracer. The actual maximum power points vary with conditions such as the surface temperature and the quantity of solar radiation. So, relationships between the maximum power point and circuit variables such as open circuit voltage and short circuit current were examined under various conditions appearing in the PV power generation system. It was found through measurements that the relationship between the maximum power and the current that the output power was almost a linear function in the actual solar arrays, regardless of the weather conditions. The MPPT method was proposed based on the obtained findings. It was verified through simulations and experiments that the proposed method enables the solar arrays to quickly generate the maximum power as determined by weather conditions at the time.

Proceedings ArticleDOI
13 Oct 2002
TL;DR: In this paper, a new MPPT control scheme has been developed for permanent magnetic (PM) generator driven by a three-phase inverter to generate 350 V direct current power to the DC bus line.
Abstract: According to the aerodynamical characteristic of the wind turbine, a maximum power point tracking (MPPT) is necessary to get high efficiency for wind power conversion, which means that the rotating speed of wind turbine should be adjusted in the real time to capture maximum wind power. Because of the fast variation of wind speed and the heavy inertia of generator, the MPPT control of wind generation is much challengeable. A new MPPT control scheme has been developed for permanent magnetic (PM) generator driven by a three-phase inverter to generate 350 V direct current power to the DC bus line. The main differences between the method used in the proposed MPPT system and other techniques used in the past are as follows: (1) the tracking step is variable according to the change of wind speed; (2) in order to avoid the dead time effect of the inverter the MPPT control is synchronized to the rotating speed of the generator; (3) a low pass filter is used at the output of the MPPT controller to decrease the fluctuation of the rotating speed reference. The resulting system has high-efficiency, lower-cost and fast, stable tracking speed. The experimental results show that it can track as fast as 0.2Hz variation of wind speed and increases the output wind power as much as 48%. As a result, the efficiency of the generation has been improved evidently.

Proceedings ArticleDOI
07 Nov 2002
TL;DR: In this paper, a power converter for coupling photovoltaic arrays to the utility grid is presented, where the converter draws a programmable, ripple-free DC current from the PV array and injects power into the grid at unity power factor.
Abstract: This paper presents a power converter for coupling photovoltaic arrays to the utility grid. The converter draws a programmable, ripple-free DC current from the photovoltaic array and injects power into the grid at unity power factor. The programmable input current feature makes this converter ideal for use with maximum power point tracking technology. The proposed converter has an additional unique feature in that the internal dc link carries a large (approximately 25%) ripple voltage. Allowing a large ripple on the DC link reduces the required size of the link capacitor. This paper includes basic system information, analysis of filter requirements, controller design and preliminary hardware results.

Proceedings ArticleDOI
05 Nov 2002
TL;DR: In this paper, a fuzzy controller is used for maximum power point tracking for PV systems, where the short circuit current of PV cell represents illumination, and the output circuit voltage carries on information about the temperature.
Abstract: Maximum power point tracking for PV systems traditionally uses either perturbation and observation method or incremental conductance method. Both methods require modulation of the output voltage and this leads to significant power loss. In this paper, a method, which senses output circuit voltage and short circuit current and use the above two parameters for optimum control with a fuzzy controller, is introduced. The short circuit current of PV cell represents illumination, and the output circuit voltage carry on information about the temperature.

Proceedings ArticleDOI
05 Nov 2002
TL;DR: In this paper, an improved MPPT converter with current compensation method for small-scaled PV-applications is presented, which implements maximum power point tracking (MPPT) by variable reference current which is continuously changed during one sampling period.
Abstract: An improved MPPT converter with current compensation method for small-scaled PV-applications is presented in this paper. The proposed method implements maximum power point tracking (MPPT) by variable reference current which is continuously changed during one sampling period. Therefore, the proposed MPPT converter with current compensation method increases the power transferred to the load above 9%. As a result, the utilization efficiency of the photovoltaic (PV)-module can be increased. In addition, as it doesn't use a digital signal processor (DSP), this MPPT method has the merits of both being cost efficient and having a simple control circuit design. Therefore, it is considered that the proposed MPPT method is proper to use for low power, low cost PV-applications. The concept and control principles of this improved MPPT method are explained in detail and the validity of the proposed method is verified through several simulated results.

Patent
31 Jul 2002
TL;DR: In this paper, a simple feedback control loop, in conjunction with an improved maximum power point tracking intermediate controller, can be used to ensure efficient operation of a power generator, which is particularly beneficial in fuel cell generator systems and other systems where damage to generator components can occur if operated above a maximum allowable power output level.
Abstract: A simple feedback control loop, in conjunction with an improved maximum power point tracking intermediate controller, can be used ensure efficient operation of a power generator. The improved maximum power point tracking controller operates the generator at its maximum allowable power point. A power output of the generator is measured and compared to a power output setpoint. Operating characteristics of the generator are then adjusted to cause the maximum allowable power point and measured power output to approximate the power output setpoint. Although applicable to all types of generators, this is particularly beneficial in fuel cell generator systems and other systems where damage to generator components can occur if operated above a maximum allowable power output level. In other systems, the maximum allowable power output may approach or equal a maximum power point (or maximum possible power point).

Patent
21 Mar 2002
TL;DR: In this paper, a power inverter using a microprocessor directly drawing the switching transistors and a circuit for computation of the actual power delivered to the load of a switching inverter is presented.
Abstract: The invention discloses a power inverter using a microprocessor directly drawing the switching transistors and a circuit for computation of the actual power delivered to the load of a switching inverter. In addition, load variation power is achieved by adjusting the frequency or the pulse width of each half cycle and, in the case where a lamp or panel is involved, dimming. Also disclosed is that the microprocessor can be responsive to photometric input to adjust output as well as power line carrier information supplied on the input power to the device.

Patent
24 Jun 2002
TL;DR: In this article, a microcomputer for controlling at least a boosting circuit and an inverter circuit so that AC power suitably usable as the AC power of a commercial power supply system can be supplied to the commercial Power Supply system is presented.
Abstract: In a solar energy generator including a solar battery a microcomputer for controlling at least a boosting circuit and an inverter circuit so that AC power suitably usable as the AC power of a commercial power supply system can be supplied to the commercial power supply system, the power to be supplied to the various kinds of equipment of the solar energy generator is selectively supplied from one of the solar battery and the commercial power supply system. The microcomputer stores the operational status data of the solar energy generator into an external storage device, and these data can be used for maintenance or trouble shooting of the solar energy generator.

Patent
12 Apr 2002
TL;DR: In this paper, an inverter unit converts power from a solar battery into AC power and interconnects the AC power with a utility power supply, and if the time is equal to or longer than a predetermined time, it is determined that one day has passed.
Abstract: An inverter unit converts power from a solar battery into AC power and interconnects the AC power with a utility power supply. A control circuit manages the time during which the inverter unit stops. If the time is equal to or longer than a predetermined time, it is determined that one day has passed. Data for one day stored in a memory is accordingly cleared and data is newly stored in the memory.