Showing papers on "Stand-alone power system published in 1994"

Energy Storage for Power Systems

Abstract: The supply of energy from primary sources is not constant and rarely matches the pattern of demand from consumers. Electricity is also difficult to store in significant quantities. Therefore, secondary storage of energy is essential to increase generation capacity efficiency and to allow more substantial use of renewable energy sources that only provide energy intermittently. Lack of effective storage has often been cited as a major hurdle to substantial introduction of renewable energy sources into the electricity supply network. The author presents here a comprehensive guide to the different types of storage available. He not only shows how the use of the various types of storage can benefit the management of a power supply system, but also considers more substantial possibilities that arise from integrating a combination of different storage devices into a system. This book will be important to those seeking to develop environmentally sound energy resources.

Wind-powered electricity generating system including wind energy storage

Abstract: The invention provides a wind-powered electricity generating system including a wind energy storage and recovery device. The wind energy storage and recovery device includes a wind-powered electricity generator (not necessarily a system of the invention), a heater operable with electricity from the generator, thermal fluid heated by the heater, a tank to store the heated fluid, and a stored heat energy extractor. In addition to the storage and recovery device, the system of the invention also includes blades mounted to rotate a shaft of a wind-powered generator in response to the wind to create electricity, and switch means actuable in response to the amount of electricity created by the generator for applying electricity to the heater. In another aspect the invention relates to a method for storing wind energy.

Use of renewable sources of energy in Mexico case: San Antonio Agua Bendita

Abstract: This paper presents a project undertaken in Mexico to electrify the remote village of San Antonio Agua Bendita (SAAB) using a custom designed hybrid power system. The hybrid power system will provide grid quality electricity to this community which would otherwise not have been electrified via traditional distribution lines. The hybrid power system was designed to electrify the entire community, incorporate multiple sources of renewable power with on-demand power, operate autonomously, and be cost effective in dollars per watt of electricity generated over the system's usable life. A major factor in the success of this project is the use of renewable energy for economic development and community partnership. Many rural electrification projects have provided power for domestic use but few have successfully provided power to improve the economic condition of the people served by the system. The SAAB hybrid avoids this pitfall by providing 120 VAC power at 60 Hz to anticipated industrial loads in the village, as well as providing grid quality power for domestic use. The system consists of the following modules: a controller, battery storage, a PV array, two 1O kW wind turbines, a diesel generator, a micro-hydro generater, power output control. >

Solar Thermal Electricity Generation

Abstract: This paper concentrates on solar thermal electricity generation and such promising technologies as trough collectors, tower plants, solar chimneys and Dish/Stirling systems. It is shown that the de...

Natural energy powered motor starter utilizing a capacitor circuit charged by a solar panel

Abstract: A starter for a natural energy powered motor comprises, an electricity storage means connectable to be charged with electrical energy from a natural energy source, a voltage conversion means are provided to step up the charging voltage to the electricity storage means. An energy level sensor means is connected to the electricity storage means to sense a predetermined maximum charging level and to thereupon in use trigger discharge from the storage means of sufficient electrical energy to start to motor to be driven by electricity from the natural energy source in use.

A photovoltaic-diesel hybrid generation system for small islands

Abstract: As a part of the New Sunshine Project carried out by the Agency of Industrial Science and Technology of MITI, the New Energy and Industrial Technology Development Organization has commissioned Okinawa Electric Power Co. Inc. And Mitsubishi Electric Corporation to jointly develop the practical technology for a photovoltaic-diesel hybrid generation system for small islands. The project involves constructing, on a small island, a stand-alone power system which uses photovoltaic power (solar arrays of 750 kW) as the main source and diesel power (300 kW) as the auxiliary source. It is designed to supply electric power to private houses which are isolated from existing distribution lines.

Emission Costs, Consumer Bypass and Efficient Pricing of Electricity

Abstract: Electricity generation causes external costs because of the emission of air pollutants. Pricing an electric utility`s service at the sum of the utility`s marginal generation cost and marginal emission cost, however, is inefficient due to {open_quotes}bypass{close_quote} by large industrial customers and the need to maintain the utility`s financial viability. This paper derives the optimal tax on emission and efficient prices for retail service to two customer classes, one of which has the option to self-generate. These rules are used to evaluate the pricing proposals made in a recent rate case in California. These proposals are shown to be inefficient, in that they encourage over-consumption by residential customers who do not have access to alternative sources of electricity supply. 9 refs.

Photovoltaic power system applications

Abstract: This article is an overview of Photovoltaic Power System applications. Photovoltaic power system range in size from watts to megawatts. They are the most modular of all electric power generating systems. PV systems produce electricity for a wide variety of applications. They can be placed in almost any location in the world, and beyond when space applications are included. When PV power for watches, calculators, and similar consumer electronic products is included in the definition of PV power system, system sizes are even smaller and applications more numerous.

Portable electrical power supply

Abstract: A portable power supply is shown generally at 10. The power supply comprises a sealed rechargeable lead acid battery 11 to which is connected a charging circuit 12 for charging the battery 11. A switching unit 13 controls the switching of power from the battery 11 either to accessory sockets 14 or to power output leads represented by 15. Between the switching unit 13 and the power output leads 15 are a reverse-polarity protection circuit 16, a vehicle-start test/timer unit 17 and a stand by/monitor circuit 18, the operation of all of which will be described below. The power supply apparatus 10 is primarily for use in the supply of 12 V dc electrical power at locations remote from conventional electricity supplies. The battery 11, at the heart of the apparatus, can be recharged from either a domestic mains electricity supply, using an integral mains charger unit 19, or from a 12-18 V dc source, such as a vehicle cigar lighter socket, a photovoltaic solar cell array, a wind-driven generator etc. using an integral 12 V dc charger lead 20.

A new method for optimising the operation of stand-alone PV hybrid power systems

Abstract: This paper describes a new method for optimising the operation of stand-alone hybrid power systems containing some combination of auxiliary generator, PV generation and storage battery. The method provides a fast and accurate solution to the optimisation problem relative to previous methods. The method has been implemented on computer and an example control policy produced by the new method is presented and discussed. A comparison has been made between the new method and a conventional control algorithm under a simulation environment and using a deterministic future. This comparison has identified potential to reduce system operating costs.

Power conditioning: The link between solar conversion and consumer

Abstract: The power conditioning for two forms of renewable energy, wind and photovoltaics (PV) links electric power generation to the consumer with requirements that provide the main control inputs for the power flow. In addition to the coupling of PV and wind energy plants to existing grids, stand-alone systems are described. The latter offer early potential for market introduction of renewable energies at a premium price, since remote supply of electricity is currently linked with higher cost. In order to reduce the cost and to improve availability, the scalability to any nominal power and the suitability to central and decentral applications is discussed on the system level. The basic variants of converter technology in conjunction with current concentration are explained and assessed in regard to PV application. For wind energy conversion, the interaction between mechano-electrical transformation, grid connection, and control concept are analysed. Grid- and consumer-specific measures for power conditioning are displayed and analyzed with regard to voltage variation and harmonics. Concepts that are successfully used in practice are presented, main causes of disturbances of operating plants are listed, and new trends are outlined. For stand-alone systems, a combination of synchronous machines and battery-coupled inverter is suitable for grid formation. Withmore » advanced control methods, the standard permissable tolerances of voltage, frequency and harmonics can be achieved. Modular unit-kit construction allows high reliability and simple installation, operation and low maintenance, and the expansion of the supply system according to increasing needs. 35 refs., 61 figs., 1 tab.« less

Energy storage as a structural unit of a power system

Abstract: The diversity of applications of electricity and particularly the fact that some of its uses, such as lighting and space heating, are subject to substantial seasonal variation makes the economic ideal of supply for constant consumption throughout the year unrealistic. There should be an intermediate unit between producer and customer that can coordinate them. This intermediate unit therefore has to be able to separate partly or completely the processes of energy generation and consumption in the power system. Secondary energy storage in a power system is any installation or method, usually subject to independent control, with the help of which it is possible to store energy, generated in the power system, keep it stored and use it in the power system when necessary.

Modern power conversion for complementary energy storage

Abstract: Similar to the classical solution of hydraulic pump-turbine plant, new means for accumulation of eletrical energy are given for lower but respectable quantities by the so called BESS (Battery Energy Storage System) and SMES (Super conducting Magnet Energy Storage). Another energy accumulator is given by using mecanichal kinetic energy of fly-wheel. Each system has advantages and disadvantage from the point of wiew of the quantity of stored energy and magnitude of the instantaneous usable power. A realistic application of energy storage, using the advantages of their complementarity. The modern energy conversion techniques allow fast, and flexible power control, and also reactive power compensation.

Development of a distribution line state monitoring and controlling system by combination of remote control switches with new optical current sensors

Abstract: As the advanced information age continues to develop, customers' needs for a stable electricity supply and the efficient consumption of electricity are continuing to expand. To enhance power supply reliability, The Kansai Electric Power Co. has been extending its automatic power distribution operating system to its entire service area (covering about 11 million users) since 1989. To reduce service interruption time over long distance distribution grids in rural service areas, the authors have developed a "distribution line state monitoring and controlling system" that minimizes failure-affected service areas by detecting failures such as grounding, short-circuits, and open phase failure. This system employs a unique form of cost reduction, with no voltage sensors incorporated. Optical sensor elements have also been developed to maintain high reliability of power systems that are exposed to harsh environments, such as on the top of outdoor utility poles under temperature extremes. >

Conveision of natural gas to electricity in fuel cells

Abstract: Publisher Summary The current discussions on atmospheric pollution and greenhouse warming have focused on the use of more environmentally friendly fuels and technologies for electricity generation, and natural gas may develop into the preferred fuel for power stations as pollutant output from gas fired power stations are substantially lower compared to coal fired ones. For example, particulate and SO x emissions are small and NO x emissions only in the range 150 ppm. Similarly, efficiencies of natural gas fired power systems are higher resulting in lower emissions of the greenhouse gas CO 2 . Central station power generation with a long distance distribution grid has further disadvantages such as (i) substantial losses during transmission resulting in decreased efficiencies at the user site and (ii) complex and difficult load demand management. Dispersed power generation at the user site overcomes these problems, but this option is severely limited with current generation technologies because of cost, size, and scaling constraints and pollution aspects. Fuel cells overcome these constraints and are low polluting. They are modular in construction and thus easy to scale, have high electric efficiencies—for some future advanced fuel cells, systems efficiencies up to 75% have been predicted—and they lower pollutant output by several magnitudes. Therefore, they are ideal for dispersed power generation and have the potential to revolutionize future electricity generation, but substantial development effort is still required to bring this technology to the market place.

Conversion of stand-by-generator facilities to combined heat and power units

Abstract: Effective use of energy could considerably extend the life of existing fuel resources and make the introduction of new sources much less urgent. One possible alternative is combined heat and power from stand-by-generators of which the United State of America has a relatively high capacity in this regard. Many organizations dependent on electricity have diesel generator sets as a backup in the event of failure of the main electricity supply. More recently it was noted that the local electricity had a peak demand period covering times when the factories were not operating and stand-by-generators were idle. Conversion of stand-by-generator facilities to CHP units allows them to be used for profitable generation of electricity and heat. The first part of the paper involves the studies carried out by author to determine the availability of nonrenewable sources of energy today and in the future as well as the environmental impact of using energy. The second part of the paper presents a fundamental design of CHP from stand-by-generators of Monash Medical Centre (case study) and modification of the entire system to enable units to operate as a sustained basis and in parallel with the main electricity supply and also some suggestions from the author for cogeneration systems using a single fuel to simultaneously produce two forms of energy usually useful heat and electricity. >

TRIMODE power converter optimizes PV, diesel and battery energy sources

Abstract: Conservatively, there are over 100,000 localities in the world waiting for the benefits that electricity can provide, and many of these are in climates where sunshine is plentiful. With these locations in mind a prototype 30-kW hybrid system has been assembled at Sandia National Laboratories (SNL) to evaluate the performance, reliability and economics of photovoltaic, diesel and battery energy systems managed by a TRIMODE power converter. In the power converter, four IGBTs with an isolation transformer and filter, serve as rectifier and charger to charge the battery from the diesel; as a standalone inverter to convert PV and battery energy to AC; and as a parallel inverter with the diesel-generator. Whenever the diesel is supplying the load, an algorithm assures that the diesel is running at maximum efficiency. Test results are showing the feasibility of the TRIMODE power converter in multi-sourced, hybrid energy systems.

An overview of power quality

Abstract: The quality of the electric power available to the end user is a matter of increasing concern to the power systems engineer. In many ways most of electric power engineering has been devoted to the enhancement of the quality of the power supply since the beginning of the use of electricity as a primary source of energy. However, in recent times, the proliferation of a wide variety of microelectronic devices into the electric power system has caused the issue of power quality to become one of critical importance to both the supplier and the user of electricity. This presentation reviews the power quality problem. its causes, proposed methods for mitigation of the problem and current and future associated research activities. >