Showing papers on "Stand-alone power system published in 1990"
Patent•
09 May 1990
TL;DR: In this paper, an uninterruptible power supply is disclosed having an inverter that operates on either high voltage d.c. supplied by a line-powered power supply or on low voltage batteries.
Abstract: An uninterruptible power supply is disclosed having an inverter that operates on either high voltage d.c. supplied by a line-powered power supply or on low voltage d.c. batteries. With line power, the inverter operates as an H-bridge inverter. With battery power, the battery voltage is applied to a smaller portion of the inverter's transformer primary. The changeover from line to battery power is determined by when an intermediate voltage tapped from the transformer drops below the battery voltage.
45 citations
Patent•
22 Feb 1990
TL;DR: In this article, a closed circuit fluid heat transfer system collects heat from the heat storage chamber and powers a turbine, which is not used in the closed circuit system, and the turbine powers an electrical generator.
Abstract: A solar energy system for generating electricity. The system tracks the sun during the day to produce a concentrated beam of light which is focused through a fixed opening in a heat storage chamber. The beam of light pressurizes the chamber and seals the fixed opening to prevent depressurization of the chamber. A closed circuit fluid heat transfer system collects heat from the heat storage chamber and powers a turbine. Heat powers the closed circuit system. A pump is not used in the closed circuit system. The turbine powers an electrical generator.
23 citations
Patent•
20 Sep 1990TL;DR: In this article, a power supply with two capacitors with energy storage is proposed to provide improved voltage regulation for the power supply and also serves to store the energy contained in voltage spikes that could otherwise deleteriously effect the supply.
Abstract: A power supply with energy storage means in the form of two capacitors with energy storage means provides improved voltage regulation for the power supply and also serves to store the energy contained in voltage spikes that could otherwise deleteriously effect the power supply.
13 citations
TL;DR: In this paper, a 25 kW rural area power supply (RAPS) system consists of a simple, low-cost furnace/boiler to generate steam which powers a simple reciprocating steam engine to drive an alternator to supply the load.
10 citations
01 Jan 1990
TL;DR: In this article, the viability of photovoltaic systems as an alternative to the grid extension or diesel power plants, for the electrification of south of Algeria (Sahara), is obtained by a net present value analysis.
Abstract: The viability of photovoltaic systems as an alternative to the grid extension or diesel power plants, for the electrification of south of Algeria (Sahara), is obtained by a net present value analysis. The accurate energy needs and the unavailability of commercial fuel in some regions offer a rewarding opportunity for the utilization of locally available renewable energy sources. Among these sources, photovoltaic seems to be the most promising one.
5 citations
03 Apr 1990
TL;DR: The South East Queensland Electricity Board is the third largest electricity distribution authority in Australia as discussed by the authors, and the authors describe the implementation by the utility of a co-operative project which would enable the testing and evaluation of a computer-based tele-control load management system, the development of administrative procedures, and the pilot testing of alternative domestic time of use electricity tariffs.
Abstract: The South East Queensland Electricity Board is the third largest electricity distribution authority in Australia. The authors describe the implementation by the utility of a co-operative project which would enable the testing and evaluation of a computer-based telecontrol load management system, the development of administrative procedures, and the pilot testing of alternative domestic time of use electricity tariffs. The identification of desirable further developments in the equipment was also intended. >
3 citations
21 May 1990
TL;DR: In this paper, a method of optimizing the component mix of a mini-utility is described, and a central part of the method is a novel storage dispatch strategy, which gives an exact answer to the storage dispatch problem with a minimal amount of computational effort.
Abstract: A mini-utility is a grid-connected or stand-alone system that extends utility services through small, modular, hybrid systems. Key components might include a photovoltaic system, a diesel generator, and a storage technology. A method of optimizing the component mix of a mini-utility is described. A central part of the method is a novel storage dispatch strategy. This method offers three primary methodological benefits. First, and most importantly, the method gives an exact answer to the storage dispatch problem with a minimal amount of computational effort. Second, the method can be used for any type of generation and storage technologies. Third, the method makes, it possible to examine all economically feasible system configurations rigorously. >
3 citations
03 Apr 1990
TL;DR: In this paper, the development of a statistical maximum demand meter and field tests carried out with the device are discussed, indicating that this method of maximum demand metering produces more realistic results than the thermal or block interval methods currently used, particularly when applied to rapidly varying loads.
Abstract: The development of a statistical maximum demand meter and field tests carried out with the device are discussed, indicating that this method of maximum demand metering produces more realistic results than the thermal or block interval methods currently used, particularly when applied to rapidly varying loads. Commercial tariffing by this method is also discussed.<
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12 Aug 1990
TL;DR: In this article, three generic power storage and generation methods for low import mass goals have been identified and studied: Gravitational energy generation using lunar soil, thermal energy storage using basalt rock or glass, and electrochemical storage using lunar derived electrodes or fuels.
Abstract: Recent advances in thin film solar photovoltaic converters (PV's) can furnish multimegawatt power levels during lunar daylight periods with only modest mass requirements. The extended duration of lunar night (ca. 354 hr) and the high specific mass of Earth-imported energy storage systems (regenerative fuel cells, batteries, etc.) render PV plus import storage power systems non-competitive with nuclear power plants for lunar bases. However, power storage or generation methods which can be constructed using primarily lunar materials, used either alone or with lightweight PV's, can be attractive alternatives to nuclear power. Three separate generic systems which can provide favorable low import mass goals have been identified and studied. These are: 1) Gravitational energy generation using lunar soil, 2) Thermal energy storage using basalt rock or glass, and 3) Electrochemical storage using lunar derived electrodes or fuels. Design, structural and operational features of these methods are described.
21 Oct 1990
TL;DR: It is explained how this power system provides more effective use of battery back-up power for more capacity, faster recharge after discharge, longer life, and less investment.
Abstract: Described is a system that regulates voltage to the load. It is also efficient and incurs some economic benefits. It is explained how this power system provides more effective use of battery back-up power for more capacity, faster recharge after discharge, longer life, and less investment; has, during normal (not emergency) operation, rectifiers that are more efficient, have less connected load for emergency generator sizing, and are used more efficiently for battery recharging and float, and provides voltage regulation that does not cause inefficiencies during normal plant operation, causes only minimal inefficiencies during emergency operation (and then only for a short time), and is within 0.10 volts whether normal or emergency conditions exist. >
TL;DR: In this article, the authors take up the basic problem seen in every from of supply - the importance of its diversification, especially that of A.C. frequency, and propose a new system for an electricity power supply, which enables to cope with various demands of consumers appropriately.
Journal Article•
TL;DR: The impact of utility-interactive residential photovoltaic (PV) power systems on the electric utility was studied in this article, where power flow analyses were performed before and after the introduction of PV, on a subtransmission and distribution network model of an actual residential utility feeder serving a suburban area of Helwan in Cairo, Egypt.
Posted Content•
TL;DR: In this article, a least-cost investment plan for the coal-based thermal electricity in the Eastern region of India was developed. But the problem has been posed as a static mixed-integer programming exercise because of indivisibilities in generation and transmission capacities and scale-economies in electricity generation.
Abstract: This study develops a least-cost investment plan for the coal-based thermal electricity in the Eastern region of India. It expands the generation and transmission capacities as on 31st March 1981 in such a way that the regional demand for thermal power during 1989-90 is met at the minimum possible cost. The problem has been posed as a static mixed-integer programming exercise because of indivisibilities in generation and transmission capacities and scale-economies in electricity generation. The study presents three reference solutions and sensitivity of one of them with regard to demand estimates, fuel prices and power loss co-efficients.
01 Jan 1990
TL;DR: A 500 watt peak tracking PV power generation system has been installed and tested in Leh as mentioned in this paper, which provides power for running DC tubelights (24 V and 48 V) at different places.
Abstract: A 500 watt peak tracking PV power generation system has been installed and tested in Leh. The system provides power for running DC tubelights (24 V and 48 V) at different places. The system is designed using our measurements of power generation in November. The load demand can be met throughout the year with our design. A cosiderable saving in diesel can result by properly mixing the PV system and existing diesel generator.
31 Aug 1990
TL;DR: In this article, the authors stress the challenges and complexities facing an engineer when designing a new facility or retrofitting an existing industrial power system, and stress the importance of power quality.
Abstract: The author stresses the challenges and complexities facing an engineer when designing a new facility or retrofitting an existing industrial power system. Industrial facilities are making more efficient use of their energy from all sources, with cogeneration being prevalent, as plants generate electricity for self-consumption and for sale to utilities. Inverter systems for uninterruptible power supplies and adjustable speed drives for AC motors also generate harmonic voltages which adversely affect the power quality. Power quality affects the reliability of the plant system. Plant shutdowns due to computer or machine tool logic failures can be as expensive as those caused by a power supply interruption or an inadequately designed industrial facility. >
01 Jan 1990
TL;DR: In this article, a highefficient power electronic converter, for converting the output voltage of a solar panel, or windgenerator, to the required DC battery bus voltage has been realized.
Abstract: A well engineered renewable remote energy system, utilizing the principal of Maximum Power Point Tracking (MPPT) can be more cost effective, has a higher reliability and can improve the quality of life in remote areas. A highefficient power electronic converter, for converting the output voltage of a solar panel, or windgenerator, to the required DC battery bus voltage has been realized. The converter is controlled to track the maximum power point of the input source under varying input and output parameters. Maximum power point tracking for relative small systems is achieved by maximization of the output current in a battery charging regulator, using an optimized hill-climbing, inexpensive microprocessor based algorithm. Through practical field measurements it is shown that a minimum input source saving of 15% on 3 - 5 kWh/day systems can easily be achieved. A total cost saving of at least 10-15% on the capital cost of these systems are achievable for relative small rating Remote Area Power Supply (RAPS) systems. The advantages at larger temperature variations and larger power rated systems are much higher. Other advantages include optimal sizing and system monitor and control.