Showing papers on "Maximum power principle published in 1982"

A simplified maximal power controller for terrestrial photovoltaic panel arrays

Abstract: Perusal of the V-I characteristics of commercial solar panels with insolation, ambient temperature and production spreads as parameter, indicate that the maximum power is obtained from such a panel when it is loaded to a working voltage that is a fixed percentage of its open circuit voltage within (+2)%. This contribution describes a system that uses this characteristic to achieve maximum power control by determining the open circuit voltage and automatically loading the panel to the maximum power point as applied to a battery charging installation. The description includes the application of a novel modified darlington circuit to boost the efficiency of a pulse width controlled switch mode type regulator by reducing the darlington saturation voltage by a compensating voltage. Advanced switching technology is applied to reduce switching losses, and maximise efficiency.

Wind turbine maximum power tracking device

Abstract: A method and apparatus for controlling the level of power transferred through a stand-alone wind power generating system utilizing a wind turbine whose output is converted to electrical power by means of an induction generator are disclosed. In the disclosed system, the velocity of the wind incident upon the blade of the turbine is sensed by a velocity sensor. This information is then used to vary the excitation frequency applied to the generator to adjust the shaft speed of the turbine in proportion to the change in wind velocity. The excitation frequency is adjusted in accordance with a control algorithm so that the power output of the system is equal to a maximum fraction of available wind power at wind velocities below a pre-determined power/velocity point.

Control process for wind power installations having input signals obtained directly from the flow around the aerodynamically active and lift-generating profile

Abstract: When there is a flow around the aerodynamically active and lift-generating profile of the rotor blades of wind power installations, excellent flow conditions occur: flow separation, zero lift, equality of pressure, etc. The occurrence of these flow conditions at prescribed points of the rotor blade is determined by measurement with the aid of sensors and used to control the rotor blade adjustment. Using the described control procedure in conjunction with a rotor blade distortion for low starting wind speeds produces a limitation of the maximum power input to approximately double the value at the point of the maximum power coefficient, and a limitation of the rotor blade loading to values close to those at this point, even in the case of maximum wind speeds. As a result, a wind power installation controlled in this way can be safeguarded in a definite way against overloading and also permits the use of high and maximum wind speeds.

Pulsed-power performance and stability of 880 nm GaAlAs/GaAs oxide-stripe lasers

Abstract: The paper gives the results of an experimental and theoretical investigation of GaAlAs/GaAs oxidestripe lasers under high-pulsed-power conditions. At a pulsewidth of 18 ns the best samples delivered optical powers of more than 2 W per facet. The kink-free light/current characteristics, the well-behaved far-fields and the very-small-amplitude jitter in the optical pulse indicate a stable operation in the fundamental lateral mode up to the maximum power level. The maximum available power is found to vary less than the inverse square root of the pulse width between 20 ns and 1 ?s. Catastrophic failure of these lasers is always accompanied with damage to one or both of the Al2O3-coated mirrors. The experimental power-law dependence and the distinct levels of power limit for lasers with differently prepared mirrors can be explained by a model which assumes a heat source in the mirror plane originating from nonradiative carrier recombination at the surface.

Turbine engine power optimization control system

Abstract: Pushbutton controls are provided for the power management of a turbine powered aircraft; and these pushbuttons may be mounted on the aircraft pilot's control handwheel. The turbine engine has a maximum rated permissible rotational speed which initially increases with increasing air temperature and with increasing altitude or reduced pressure; and has an absolute maximum limitation, with this maximum permissible rotational speed decreasing at increasing temperatures starting at about 10 or 15 degrees below zero, centigrade; and these limitations are reduced when supplemental equipment such as de-icing equipment is turned on. In accordance with the present invention, a series of "maps", or rotational speed control characteristics reflecting the factors mentioned above, are provided, and the pushbutton controls select among these characteristics, with the "take-off" power button permitting the highest maximum speeds, etc. In addition, automatic timing to reduce the maximum power levels, such as "Take-Off" power or "Performance Climb" power, is provided, to avoid over-stressing the turbine engines. The system may include additional arrangements for limiting the maximum allowable rotational speed of the turbine engine to a speed below that indicated by any of the "maps", when certain pushbuttons such as the "Approach" pushbutton is actuated.

Photovoltaic array: Power conditioner interface characteristics

Abstract: The electrical output (power, current, and voltage) of flat plate solar arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as dc-to-ac power conditioners must be capable of accommodating widely varying input levels while maintaining operation at or near the maximum power point of the array. The array operating characteristics and extreme output limits necessary for the systematic design of array load interfaces under a wide variety of climatic conditions are studied. A number of interface parameters are examined, including optimum operating voltage, voltage energy, maximum power and current limits, and maximum open circuit voltage. The effect of array degradation and I-V curve fill factor or the array power conditioner interface is also discussed. Results are presented as normalized ratios of power conditioner parameters to array parameters, making the results universally applicable to a wide variety of system sizes, sites, and operating modes.

Characterization of the electrical output of flat-plate photovoltaic arrays

Abstract: The electric output of flat-plate photovoltaic arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as direct-current to alternating-current power conditioners must be able to accommodate widely varying input levels, while maintaining operation at or near the array maximum power point.The results of an extensive computer simulation study that was used to define the parameters necessary for the systematic design of array/power-conditioner interfaces are presented as normalized ratios of power-conditioner parameters to array parameters, to make the results universally applicable to a wide variety of system sizes, sites, and operating modes. The advantages of maximum power tracking and a technique for computing average annual power-conditioner efficiency are discussed.

Optimum starting control system for air conditioning system

Abstract: PURPOSE:To enable a power consumption control to be compatible with comfortableness by a method wherein, in an air conditioning system for a plurality of rooms, in the case of starting for operation through the computation of an optimum starting time, a control is performed so as to expedite a starting when a power consumption control is forecast. CONSTITUTION:The determination of an optimum starting time for cooling/heating in advance is based upon the calculation adopting learning control wherein the forecast room temperature gain at the cooling/heating time is added to the previous day's measured data. That is, the delay time TD from the maximum cooling/heating time in advance TS is calculated for determining the starting operation time. The time TS-TDis lengthened by a ratio of a demand power of a whole air conditioning system to a control power. Rooms to be air conditioned are required to be brought into their respective given temperature at their respective times being different from each other, and thereby a central controller MC computes them by each room. Thus, a maximum power consumption can be controlled within a contract demand, which results in enabling to save a basic charge.

Photovoltaic array: power conditioner interface requirements

Abstract: The electric output of flat-plate arrays changes constantly, due primarily to changes in cell temperatures and irradiance levels. As a result, array loads such as dc-to-ac power conditioners must be able to accommodate widely varying input levels while maintaining operation at or near the array maximum power point. The results of an extensive computer simulation study used to define the parameters necessary for the systematic design of array-load interfaces, including optimum operating voltage, voltage tracking width, maximum power and current limits, and maximum open-circuit voltage are presented as normalized ratios of power-conditioner parameters to array parameters to make the results universally applicable to a wide variety of system sizes, sites and operating modes.

Aerodynamic research on tipvane windturbines

Abstract: The research on tipvane turbines aims at a process improvement of the wind energy conversion system, which is more than component improvement such as efficient aerofoils and optimized transmission systems. These latter developments make it possible for a modern wind turbine to approach the Betz maximum power coefficient. However, process improvements are possible based on flow phenomena which are not consistent with the assumptions made in Betz theory. Power coefficients far above the Betz maximum value are possible when for example forces are applied perpendicular to the wind direction and when viscous effects play an important role. At the Delft University of Technology, the wind energy group investigates the effect of tipvanes, which are small auxiliary wings at the end of the turbine blades inducing a mass flow augmentation by the creation of a venturi flow.

Photovoltaic panel arrays.

Abstract: Perusal of the V-I characteristics of commercial solar panels with insolation, ambient temperature and production spreads as parameter, indicate that the maximum power is obtained from such a panel when it is loaded to a working vol­ tage that is a fixed percentage of its open circuit voltage within (+2)%. This contribution describes a system that uses this characteristic to achieve maximum power control by determining the open circuit voltage and automatically loading the panel to the maximum power point as applied to a battery charging installa­ tion. The description includes the ap­ plication of a novel modified darlington circuit to boost the efficiency of a pulse width controlled switch mode type regulator by reducing the darlington saturation voltage by a compensating voltage. Advanced switching technology is applied to reduce switching losses, and maximise efficiency.