Showing papers on "Stand-alone power system published in 1993"

A power supply and battery charging system

Abstract: A novel power charger apparatus (300) is provided for supplying electrical power to an electrical device (200) for operation or to a battery (402) for charging, or both. The charger apparatus (300) comprises a primary power supply (302) for supplying power from an external power source to the power charger (300), a power converter (306) coupled to the primary power supply (302) for converting the power received by the primary power supply (302) from the external power source into a form usable by the power charger (300), and a power controller (308) coupled to the power converter (306) for controlling the power applied to the device (200) or the battery (402), or both, whereby, regardless of the rate of charge of the battery (402), a constant current is maintained for charging the battery (402) while the voltage across the device (200) and battery (402), is allowed to vary. To observe the rate of charge of the battery (402), the power charger (300) also includes a charge rate sensor (404) connected to the battery (402) and coupled to the power controller (308) to measure the voltage across the battery (402).

Optimal capacity of the battery energy storage system in a power system

Abstract: This paper investigates the optimal capacity of a battery energy storage system in a power system. The Taiwan Power Company System is used as an example system to test this algorithm. Results show that the maximum economic benefit of battery energy storage in a power system can be achieved by this algorithm. >

Optimisation of a hybrid energy system using simulated annealing technique

Abstract: This paper reports an optimisation algorithm based upon the simulated annealing technique for a hybrid energy system The hybrid energy system is an integrated diesel-generator/battery-inverter system developed for remote communities where the supply of the main electrical power is unavailable The developed algorithm provides optimal generator setting and battery charge/discharge schedules for a given daily load cycle It has been applied to a test example and the simulation results are presented >

The solar electric house : energy for the environmentally-responsive, energy-independent home

Abstract: Solar electricity is the direct conversion of sunlight into electricity by solar photovoltaic cells. It is a truly elegant means of producing electricity on site, allowing you to take control of your energy destiny and create your own lifestyle without concern for energy supply or environmental harm. No pollution, no by-products, no depletion of resources, these solid-state devices simply make electricity out of sunlight. Solar electricity is the ideal source of power for an environmentally-responsive home where it's a luxury residence or a rustic vacation retreat. With the right design, the sunlight that falls on your homesite will power your home. Your solar electric system can also be easily configured to provide on-site recharging of solar/electric vehicles allowing you to meet your transportation needs with renewable energy.

A regulated self-excited induction generator for use in a remote area power supply

Abstract: The application of induction generators for remote area power supplies is discussed with particular reference to developing countries. The paper describes a method for calculating the minimum value of self-excitation capacitance necessary to initiate self-excitation with a stand-alone induction generator. Final steady-state self-excitation voltages and frequencies are also evaluated for both loaded and unloaded operation, taking into account the rotor parameter variations with frequency. It is shown that the calculated and measured results are in strong agreement, and for the loaded generator they agree considerably more so that when constant rotor parameters are used. Final steady-state self-excitation voltages and frequencies are shown to vary with the load demand, in some cases causing poor quality of supply. A new technique is proposed for voltage control to improve the regulation with load.

Effects of wind power generators on the voltage control of utility distribution networks

Abstract: The integration of embedded generator(s) including wind power generators (WPG) with an utility's distribution network could create many technical problems This paper briefly reviews the main problems associated with the integration of WPG(s) with utility's distribution network It also investigates the effect of the integration on maintaining the voltage magnitude of a distribution network within the statutory limits

Keeping the home fires burning

Abstract: Some utilities and thermal researchers are devising thermoelectric and thermophotovoltaic technologies to convert furnace heat to electricity and keep home heating systems functioning during extended power failures. Storms that damage power lines often leave homes without heat, since the electricity supplied to furnace blowers is cut along with all other electricity. One case in points is the March 1991 ice storm that left nearly 200,000 Rochester Gas and Electric Corp. customers without electrical power, some for up to two weeks. This led the Rochester, N.Y., utility, RG and E, to search for an independent power source that could provide homes with heat during prolonged outages. RG and E funded development of a continuous gas furnace by the GE Research and Development Center in Schenectady, N.Y., that would keep its customers' homes heated and provide some electricity during power outages. Since natural gas lines are rarely interrupted during a power outage, the furnace is still a potential source of heat, but only if there is some way to supply electricity that is independent of the grid, said Bruce Snow, manager and chief engineer of the technical services division at RG and E. The electricity would power the furnace blower, which blowsmore » hot air through air ducts, or run the motor that pumps water through a piping system to keep the house warm. Such a thermoelectrical system involves heating the two junctions of thermocouples, which are made of dissimilar wires, at two different temperatures in order to create electricity. A newer technology, thermophoto-voltaics, also converts heat to electricity. In this process described here, the heat causes an emitter to radiate a wavelength of light, which is converted into electricity by a photovoltaic unit.« less

Small grid-connected solar photovoltaic generators in the UK

Abstract: This paper examines the engineering, commercial and regulatory aspects of the grid connection of small photovoltaic power systems in the UK, and compares the situation with other European countries where several thousand systems are being installed under either sponsored or independent programmes. Data was gathered from study of the European experiences and from extensive interviews within the electricity supply industry in the UK. The study concludes that the systems are technically feasible using currently available technology, although their widespread use in this country is held back by economic and organisational barriers. A technical guidelines document is also available from the study for those wishing to pursue such schemes. >

Method for judging quality of storage battery of uninterrutible power supply unit

Abstract: PURPOSE:To make the discharge current flow in an appropriate amount for judging quality of s storage battery, while continuing the power supply to a load. CONSTITUTION:An uninterruptible power supply unit is provided with a self- exciting converter 2 for converting the alternating current power form a commercial power source 1 into the direct current power, a self-exciting inverter 3 for converting the direct current power to the alternating current power to supply it to a load 4, and a storage battery 5 for supplying the direct current power to the inverter 3 at the abnormal time of the commercial power source 1. Under the condition that the power supply to the load 4 from the inverter 3 is continued, the direct current output voltage of the converter 2 is controlled at a constant value equal to a storage battery starting voltage or less and possible to operate the inverter 3, and the storage battery 5 is operated for discharge, and quality of the storage battery 5 is judged on the basis of this discharge current.

Automotive power distribution and switching system

Abstract: An automotive battery switching and distribution system which includes a battery system in combination with an integrated power switching system, for providing protection for the battery system by synchronizing the battery system's discharge rate with the electrochemical reactions of the battery system. The battery system has at least two discharge characteristics, one capable of short high current discharge of electric power for cranking an internal combustion engine, and the other for providing a lower rate of current discharge as required for vehicle auxiliary power. The power switching system acts in response to increased voltage or current levels to connect or disconnect the battery with related loads or power sources as necessary for optimum battery protection and system operation. Each portion of the battery system is separately connected to the electrical system of the automobile so that draining one portion of the battery system will not affect the electrical system that is connected to the other portion of the battery system.

Modular, hybrid power system

Abstract: A power system provides various levels of electrical power at various radio frequencies to specific input locations of a neutral particle beam accelerator system. Both the power system and the accelerator system are mounted on a space platform. The power system includes separate modules mounted on two hinged members of the platform. The modules utilize turbines, generators and fuel cells to provide the needed electrical power which is amplified to the desired levels required by the accelerator system. In addition, a fuel cell is utilized to power a pulse drive motor to drive the generators during turbine start up in order to provide high voltage output power during the start up. A regenerator produces hydrogen and oxygen from the water effluent produced by the fuel cells and the combustors which powers the turbines thereby recycling the fuel and working fluid and consequently making the power system generally non-contaminating and fuel efficient. A thermal management subsystem circulates hydrogen through both the accelerator and power systems, and the hydrogen is utilized as both a coolant and a fuel/working fluid for power production thereby enhancing the energy efficiency of the power system.

Probabilistic design of high quality power supply photovoltaic systems

Abstract: The stand-alone application of photovoltaic (PV) systems, at current industrial production technological levels, could provide a viable solution to the problem of producing electricity for users located far away from power distribution systems. The author discusses the criteria for calculating the sizes of PV peak power and energy storage of a highly reliable power supply for special loads, with the aim of reaching the desired availability level. Adopting the criteria of loss of load probability (LOLP), the sizes of PV peak power and energy storage of the system are calculated in two steps. An initial provisional calculation is made, followed by a simulation of the most critical conditions, as a sequence of days with a minimum level of irradiation calculated probabilistically. A simple iterative process is adopted to evaluate performance. >

Optimising unit commitment in an island power system

Abstract: The Electricity Supply Board (Ireland) is a vertically integrated electric utility which operates generation, transmission and distribution of electricity in the Republic of Ireland. The power system is not connected electrically to any other and is referred to as an 'island' power system. In common with other island power systems, operational problems are posed as a consequence of the largest generation infeed being a substantial portion of the customer demand and providing for the loss of this infeed can be difficult and costly. Special generation dispatch and unit commitment algorithms are needed in such systems and this paper describes the unit commitment algorithm used by ESB and the framework within which it operates. The special operational constraints in ESB's power system are described, the relevance of these to the unit commitment problem is indicated and the experience gained in daily operation of the system is discussed. >

Rathlin Island wind/diesel/battery system

Abstract: Since 1972 the Rathlin Island community has wanted to acquire a mains supply of electricity for the island. Wind power was becoming increasingly possible and proposals for a wind/diesel/battery power system were first noted in 1990. The authors describe how, in 1991, an outline design for a hybrid scheme comprising three diesel-electric generators coupled with three wind energy conversion units and utilising battery storage as a buffer to minimise diesel startups was adopted. Site construction work started in January 1992 and the system was officially energised on 16 October 1992.

Power generation in Sri Lanka: status and future options

Abstract: The operation of the unique electricity generating system in Sri Lanka with its often conflicting priorities for power and irrigation is already a challenge to its power engineers. Planning of system operations in the short, medium and longer terms is subject to too many variables not encountered in many other generating systems. With most of the hydroelectric potential in the country already developed, the future generating system will require large, baseload thermal generation. It is a power system in transition.

Training Simulators For Power System Operation In Power Utilities Of Japan

Abstract: Present si tuation of dispatcher training simulators for power system operation i n Japan is surveyed. Simulatoraided education/training programs now widely implemented i n power companies a re a l so referred. Specifically, t h i s paper presents Japan's recent s t a t u s of power sysLem opera t ion , objective of a training simulator, simulation models of power system dements , man-machine in t e r f ace , layout of t ra in ing simulator f a c i l i t i e s , t ra in ing/educa t ion programs, fu tu re challenges i n power companies, and s o forth.

Norwegian Power Market: Uniform transmission tariffs seek to improve the effciency of Norway's electric supply

Abstract: he power transmission networks are operated as one physically integrated transport system on which any seller or buyer of power can get the power transported from any point of input to any point of delivery based on uniform transmission tariffs subject to control by the government regulatory agency. The objective of the new energy act is to improve the efficiency of the electricity supply in the country. One basic feature of the new act is that all customers, regardless of the size of their consumption, have a real opportunity to negotiate a contract of power supply from any power trader in the country. Power supply has become subject to free competition thanks to the management of the electric transmission networks.

A Practical Approach To Evaluating The Marginal Outage Costs In Generating Systems

Abstract: ( i h s t r n c t This paper presents a fornialized and p ra c t i ca I iii a r gi n a I outage costs in generating systems for the piirposes o f spot pricing. The proposed iiictliod Involves cstiniating tlic economic costs incurred by custoniers due to various outage lcvcls aiid the cffccts of load cliangcs on the probabilit ics that these costs will actually be incurred. The utilization of tiie proposed nietliod I n calciilating the marginal outage costs of a slngle generating system Is i l lustrated using the I E E E -Rel iabi l i ty Test Systein. A nuniber o f si i n pl i fy i n g assu i n p ti on s a re a Iso d i sc ussctl i n tli is p:ipcr i n order to sliow how the proposed iiicthod can I)c tailorcd to practical systeni applications. Tlic b:1sic nlct l lodology i s tl1cn cxtencled to two i II t cr con nect cd genera t iiig s ys tcm s i n ordcr to show the iinpact of capacity assistance on the iiiargiiial on1age cost. a p p roach for ca Icu 1 a t i 11 g t 11 c

A Canadian Cost Of Interruption Study

Abstract: &tract This paper outlines the procedures and presents summary results of a recent Canadian study funded by the Natural Sciences and Engineering Research Council and seven Canadian electrical utilities. The main objectives of this study are to identify and delineate more completely the characteristics, variables and criteria associated with customer costs of electric service interruptions which are considered a surrogate measure of the worth of electric power system reliability. The study utilizes the customer survey approach as its basic methodology on the basis that customers are in the best position to understand and assess how supply interruptions impact their activities. This paper presents survey results obtained from the residential, commercial, and industrial sectors.

Time-of-day electricity pricing using optimal mix of generation system

Abstract: A systemic pricing method for power systems has been developed to obtain the time-of-day price for generation plant operation assessment and the time-of-day tariffs for consumer bill. The method presented by the authors is an hourly time-of-day pricing system based on the optimal mix of generation system. By means of time-of-day pricing, power plants are encouraged to follow peak load and consumers are guided to shift their peak demand to off-peak time of system. >

Estimates of outage costs of electricity in Pakistan

Abstract: This article estimates outage costs of electricity for each of the four provinces in Pakistan (Punjab, North-West Frontier Province, Baluchistan, and Sind). The term {open_quotes}power outage{close_quotes} refers to all problems associated with electricity supply, such as voltage drops (brownouts), power failures (blackouts), and load shedding. The most significant of these in Pakistan is load shedding when power supply to different consumers is shut off during different times of the day, especially during peak hours when the pressure on the system is the highest. Power shortages mainly arise during the low-water months when the effective capacity of hydropower plants drops significantly. This decline in power supplied by hydro plants cannot be made up by operating thermal power plants because of the limited availability of gas and the high cost of alternative fuels required for the operation of gas turbines.

Application of Distributed Scada System in Electric Power Plant

Abstract: The early development of Supervisory Control And Data Acquisition (SCADA) systems has been related to the implementation of remote monitoring and control functions in power system dispatch centers. Prior to the use of the digital computers, different SCADA functions were performed by separate hardware systems each of which had its own dedicated Man Machine Interface (MMI). Thus, the first digital implementation of SCADA functions was an emulation of the hard-wired analog systems in the digital coniputers using a common MMI subsystem. This phase of development is characterized with the centralized SCADA configuration where all data processing is performed at the power system dispatch center, while power plant control system participate only as input/output (110) facilities, usually without even local processing capabilities. The centralized SCADA configuration became obsolete with the advancement of computer technology and the availability of high performance 32-bit microprocessors at dramatically reduced prices in the mid 1980's. Since that time, the major challenge for SCADA systems is the distribution of various functions among a group of interconnected computers. This led to the application of distributed control systems in power plants and their incorporation into the distributed SCADA system at the level of power system dispatch centers. The benefits of such distributed SCADA processing include the improvements in SCADA performance, greater fault tolerance, easier maintenance, extensions and upgrading, as well as life-cycle cost reductions. This paper presents an evolutionary concept of distributed SCADA system development and application at the level of electric power plant. The proposed concept is under consideration for application at several hydropower plants in Yugoslavia.