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Showing papers on "Maximum power point tracking published in 1986"


Patent
31 Jan 1986
TL;DR: In this article, a photovoltaic power control system equipped with at least one inverter for inverting an output of a solar cell array to AC power, and having charge-and discharge control means for charging a surplus portion with respect to the power for expected use of the output of the solar cell arrays to a storage battery and discharging shortage portion with regard to the energy.
Abstract: There is disclosed a photovoltaic power control system equipped with at least one inverter for inverting an output of a solar cell array to AC power, and having charge-and discharge control means for charging a surplus portion with respect to the power for expected use of the output of the solar cell array to a storage battery and discharging shortage portion with respect to the power for expected use of the output of the solar cell array from the storage battery by detecting the surplus or shortage produced between the output of the solar cell array and AC power for expected use inverted by the inverter, the improvement comprising weather fluctuation pattern selection means for selecting one weather pattern out of various kinds of weather patterns preset based on weather information at a time point when the weather is forecasted on the day when the power is generated by the solar cell array; and workable pattern selection means for selecting one actuation pattern of the inverter corresponding to the weather pattern selected by the weather fluctuation pattern selection means out of various actuation patterns of the inverter preset corresponding to the weather pattern.

45 citations


Patent
28 Oct 1986
TL;DR: A regulating A.C. power controller regulates the selected levels of power to be applied to a plurality of loads by producing a digital signal directly from the voltage with a pulse duration representative of load power which can be applied as an input to the microprocessor without the need for prior analogue to digital conversion as discussed by the authors.
Abstract: A regulating A.C. power controller regulates the selected levels of power to be applied to a plurality of loads by producing a digital signal directly from the A.C. voltage with a pulse duration representative of load power which can be applied as an input to the microprocessor without the need for prior analogue to digital conversion. The load power level is displayed in terms of percentage of power source. Remote control units, such as a computer, can be connected with the power controller to program it for power level settings and warm up time.

30 citations


Journal ArticleDOI
TL;DR: In this article, a 1-kW interactive inverter for direct photovoltaic energy feedback to the mains has been realized, where a modulated buck converter converts the dc current to a rectified 50-Hz sine wave current, and the following self-commutated half-bridge generates a 50Hz SINW current, which is fed into one phase of the public power grid.
Abstract: A new regulated utility interactive inverter for direct photovoltaic energy feedback to the mains has been realized. A modulated buck converter converts the photovoltaic dc current to a rectified 50-Hz sine wave current, and the following self-commutated half-bridge generates a 50-Hz sine wave current, which is fed into one phase of the public power grid. This nonclassical inverter needs only three power transistor switches and isolates the grid and the photovoltaic array using a commercial 50-Hz transformer. It acts as a current source, and due to pulsewidth modulation its output is a sine wave current with very low total harmonic distortion of one percent. The overall efficiency of the 1-kW prototype is at least 88 percent between 250 and 1000 W, and the projected efficiency is over 90 percent for 1-20 kW. Furthermore, a circuit which tracks the maximum power available from the photovoltaic generator has been developed. This circuit regulates the input power to its maximum by detecting the phase angle between the voltage and power ripples at the inverter input.

20 citations




Patent
Kiyoshi Ogawa1
25 Sep 1986
TL;DR: In this paper, an error signal input of an error amplifier in an active or reactive power control circuit is detected, and when the detected error signal inputs exceeds a predetermined value, a circuit breaker, which couples the power converter to an AC power system, is opened.
Abstract: In a self-commutated power converter, an error signal input of an error amplifier in an active or reactive power control circuit is detected, and when the detected error signal input exceeds a predetermined value, a circuit breaker, which couples the power converter to an AC power system, is opened. Then, any malfunctioning of the power control system or power fault of the AC power system is detected in accordance with the value of the detection voltage of the AC power system.

11 citations


Patent
27 Feb 1986
TL;DR: In this paper, a pulsewidth-modulated inverter-converter for generating a direct current output from a direct-current supply which utilizes a power inverter having smoothed trapezoidal waveform at the inverter output.
Abstract: A pulse-width-modulated inverter-converter for generating a direct current output from a direct current supply which utilizes a power inverter having smoothed trapezoidal waveform at the inverter output. A nonlinear inductive element, e.g. a reactor, is provided in series with the center tap of the primary winding of the power transformer which is connected to the power transistors of the inverter to allow storage in a capacitor upstream of this inductor of energy during the recovery times of the transistors.

9 citations


Journal ArticleDOI
TL;DR: In this article, the orthogonal-core type dc-ac converter and its application to a photovoltaic power system for connecting the solar cell array to an ac distribution line was reported.
Abstract: This paper reports the orthogonal-core type dc-ac converter and its application to a photovoltaic power system for connecting the solar cell array to an ac distribution line. In the system, a simple control circuit for tracking the maximum array power which varies with the solar radiation is presented. Good operating characteristics are obtained in the experimental photovoltaic power system.

7 citations


Proceedings ArticleDOI
23 Jun 1986
TL;DR: In this paper, the authors present the design and realisation of a DC/AC inverter with a reversible power cell, which enables the handling of highly reactive loads, and a state variable feedback study leads to the large signal mastery of the power cell.
Abstract: In this article, the authors present the design and realisation of a DC/AC inverter. The power cell described is reversible and thus enables the handling of highly reactive loads. A state variable feed-back study leads to the large signal mastery of the power cell. The adaptation of the feedback loop for load variations and source voltage variations are also considered. The article concludes with the presentation of measurements made on a breadboard realisation which testifies as to why this power cell and its control law become a focus of interest.

7 citations


01 Sep 1986
TL;DR: In this paper, a study was conducted to determine the effects utility-interactive photovoltaic power systems would have on the utility distribution feeder and the effect inverter harmonic currents on the harmonics in the utility voltage.
Abstract: A study was conducted to determine the effects utility-interactive photovoltaic power systems would have on the utility distribution feeder. The study focused on the effect photovoltaic generated power would have on the feeder voltage regulation and the effect inverter harmonic currents would have on the harmonics in the utility voltage. Up to 30% of the homes were assumed to have photovoltaic power systems with a nominal 5.5 kW rating. The short suburban feeder and the long rural feeder appeared to behave about the same for the same percentage of the homes with photovoltaic power systems. No significant problems were found that would limit the application of utility-interactive residential photovoltaic power systems in the cases studied.

6 citations



Book ChapterDOI
01 Jan 1986
TL;DR: In this paper, the authors examined the parameters involved in determining the distance from utility power at which a stand-alone photovoltaic power system is economically justified, and found that PV systems are cheaper than propane or diesel power for up to 3 KWh per day of usage.
Abstract: This paper examines the parameters involved in determining the distance from utility power at which a stand-alone photovoltaic power system is economically justified. The life cycle costs of a range of hybrid photovoltaic/generator systems (from 0.5 to 20 KWh per day) are compared to equivalent utility power usage and connection costs to derive minimum distances from the power grid. It was found that photovoltaic power systems are cost effective today for many remote sites. High utility connection fees and lower PV module prices significantly improve viability. Utility rate increases have no significant economic effect. The loss of tax credits mainly affects smaller systems. With current U.S. tax credits, PV systems are cheaper than propane or diesel power for up to 3 KWh per day of usage. Without tax credits, generator power is equivalent in cost to about $5 per peak Watt in photovoltaic power.

Journal ArticleDOI
TL;DR: In this article, the power and voltage control loop of a thermal power plant of 180 MW was modeled based on full-scale measurements at the Flevo power plant, and a relatively simple ninth-order mathematical model of one unit for several working points has been developed.
Abstract: This note describes the modeling of the power and voltage control loop of a thermal power plant of 180 MW. The modeling is based upon full-scale measurements at the Flevo power plant of the PGEM. A relatively simple ninth-order mathematical model of one unit for several working points has been developed. Based on this model the existing controller structure has been analyzed and an improved voltage control system designed. The design method is based on a state-feedback technique and pole placement. By means of computer simulations in an extended nonlinear model of this unit, including the grid, the existing and the newly developed control algorithms are compared. Field tests have been carried out to verify the results of the designed control algorithms.