Showing papers on "Power optimizer published in 1978"

Wind turbine generator pitch control system

Abstract: Wind energy is used to drive a wind turbine, which is in turn connected to an electrical generator to produce electrical power. The pitch angle of the wind turbine blades is controlled in a closed loop manner to maintain either a constant generator speed for isolated power generating stations or when the generator is synchronized to the load, or constant generator output power or shaft torque when the generator is connected to an electrical grid. Open loop acceleration and deceleration schedules are provided to minimize blade stress and shaft torque variations during start up and shutdown transients, limiting blade angle excursions as a function of wind velocity and speed. The schedules may be implemented either electronically or by a suitably programmed digital computer. The gains in the speed, torque and power loop controls are scheduled as a function of average wind velocity to optimize stability and response. An anticipatory blade angle schedule responsive to instantaneous wind velocity is added to the desired blade angle reference from the closed loop controls to minimize transient excursions in output power or generator speed resulting from wind gusts.

New energy-storage dc-dc converter with multiple outputs

Abstract: New energy-storage dc-dc power converter is presented which provides multiple regulated and isolated dc output voltages. The conventional converter circuits have some defects. In the step-up-down type circuit, the operation is easy to be unstable when the feedback loop gain and/or the total output power grows larger. Meanwhile, although the operation of the step-down type circuit is stable, the extraordinary phenomena arise when the magnetomotive force of the energy-storage reactor is discontinuous for the light-load. These phenomena may be eliminated by the use of a dummy load or the reactor of sufficiently large inductance, but it makes the efficiency lower or the size and weight of the reactor larger. In the converter circuit presented here, the operation is stable and the extraordinary phenomena are eliminated by using the magnetic coupling among the multiple windings of the reactor. Hence, the dummy load can be removed and the inductance of the reactor can be made smaller.

High efficiency wind power machine

Abstract: A high efficiency wind power machine is disclosed which is particularly well suited for large-scale, commercial conversion of wind power into electrical energy. The wind power machine of the present invention employs highly efficient wind-to-electric power conversion modules which may be interconnected to form a large-scale power converter. The individual modules employs flip-flop wind blades which travel in an oval path and are carried by traveling chains. The blades interact with the impinging wind stream at two points, thus increasing the overall efficiency of the conversion modules.

AC/DC Power supply device

Abstract: An AC/DC power supply device for operating a refrigerator compressor by switching over the AC operation mode in which the compressor is operated from AC power source and the DC operation mode in which the compressor is operated from DC power source through an inverter circuit, wherein a thermostat is constructed so as to be connected to a circuit for supplying DC voltage to the inverter circuit in the DC operation mode, and a switching section is constructed so that high potential points including the potential of the AC power source and low potential points including the potential of the DC power source do not face each other in close vicinity to prevent the AC power voltage from being unwantedly applied to the low voltage side.

Advanced Photovoltaic Synchronous-Orbit Spacecraft Power Systems

Abstract: The state-of-the-art of photovoltaic power systems, for use in synchronous-orbit spacecraft, is characterized, including solar array, battery, and power control component performance. Advanced developments in each of these areas are reviewed, and performance improvement projections are made for the 1980-1990 time period. It is estimated that photovoltaic power system specific weight could improve from a present value of 126 kg/kW to approximately 43 kg/kW in 1985. These performance predictions are compared to nuclear system performance projections over the same period. The analysis indicates that advanced photovoltaic power systems will exhibit specific weights lower than isotope and nuclear reactor systems for power levels up to approximately 25 kW. At higher power levels, batteries with higher energy density would be required to compete with the projected performance of advanced nuclear systems. N this paper, we review state-of-the-art performance characteristics of synchronous-orbit power system components, discuss technology advancements, extrapolate overall system performance into the 1980-1990 time period, and finally, make alternative power system comparisons. Power subsystem performance improvement areas include solar array power density, battery energy density, and power control electronics power density. These components typically comprise 15-20% of total spacecraft weight. Increased spacecraft payload weight allocation and total system capability improvement will result from power system weight reduction.

Control of wind turbine generators connected to power systems

Abstract: A unique simulation model based on a Mode-O wind turbine is developed for simulating both speed and power control An analytical representation for a wind turbine that employs blade pitch angle feedback control is presented, and a mathematical model is formulated For Mode-O serving as a practical case study, results of a computer simulation of the model as applied to the problems of synchronization and dynamic stability are provided It is shown that the speed and output of a wind turbine can be satisfactorily controlled within reasonable limits by employing the existing blade pitch control system under specified conditions For power control, an additional excitation control is required so that the terminal voltage, output power factor, and armature current can be held within narrow limits As a result, the variation of torque angle is limited even if speed control is not implemented simultaneously with power control Design features of the ERDA/NASA 100-kW Mode-O wind turbine are included