Showing papers on "Base load power plant published in 1993"

An adaptive neural network approach to one-week ahead load forecasting

Abstract: A neural network approach is proposed for one-week ahead load forecasting. This approach uses a linear adaptive neuron or adaptive linear combiner called Adaline. An energy spectrum is used to analyze the periodic components in a load sequence. The load sequence mainly consists of three components: base load component, and low and high frequency load components. Each load component has a unique frequency range. A load decomposition is made for the load sequence using digital filters with different passband frequencies. After load decomposition, each load component can be forecasted by an Adaline. Each Adaline has an input sequence, an output sequence, and a desired response-signal sequence. It also has a set of adjustable parameters called the weight vector. In load forecasting, the weight vector is designed to make the output sequence, the forecasted load, follow the actual load sequence; it also has a minimized least mean square error. This approach is useful in forecasting unit scheduling commitments. Mean absolute percentage errors of less than 3.4% are presented from five months of utility data, thus demonstrating the high degree of accuracy that can be obtained without dependence on weather forecasts. >

An efficient load model for analyzing demand side management impacts

Abstract: The authors present an efficient technique to model the system load such that the impact of demand-side management (DSM) on the power system can be easily and accurately evaluated. The main objective of implementing DSM in power systems is to change the utility's load shape, i.e., changes in the time pattern and magnitude of the utility's load. Changing the load shape as a result of demand side activities could change the peak load, base load and/or energy demand. Those three variables have to be explicitly modeled into the load curve for properly representing the effects of DSM. The impact of DSM will be manifested as higher or lower reliability levels. The proposed technique to model the load duration curve will facilitate the representation of DSM effects on loss-of-load probability, energy not served, and energy consumption. This will provide an analytical method to study the impact of DSM on capacity requirements. So far iterative methods have been applied to study these effects. The proposed analytical method results in a faster solution with higher accuracy. It takes only 18 s on an 80486 PC to solve each case study involving different peak and base loads, and energy use. >

Water and Power

Abstract: The many ways in which water can be differentially controlled cannot easily be summarized. Water can be managed to increase agricultural production, substitute for labor, provide safety, improve trade and communications, affect health and wellness, and display power. Much of the time, water functions in several of these ways simultaneously, and all kinds of water management offer possibilities to build up inequalities in water access and the benefits that result from it. Flowing through the theme of water management is the fact that water, by nature, can be both persistent and changeable, requiring that the specific temporality of water sources must be mediated by anyone hoping to use them. Water’s fluctuations may be highly predictable or totally unpredictable: dependable events like the annual Nile floods can be harnessed to exacerbate existing social inequalities, while unforeseen events like tsunamis can destabilize existing inequalities or create new ones.

Small battery energy storage system

Abstract: A small battery energy storage (BES) system is proposed. The power circuit of this BES system is simple, since only one current-forced subharmonic PWM switching converter is used. The precise current control is achieved by applying feedforward control. If the utility power is off, the BES system operates in the inverter mode to supply power to the load. A sinusoidal output voltage with low distortion and good regulation is obtained by using instantaneous voltage control and average voltage control techniques. When the utility power recovers, the BES system minimises the power from the utility to the load in the peak load period. Conversely, the power from the BES system is minimised in the medium load period. During the off-peak load period, the utility supplies power to the load and also charges the battery bank. In addition to real power conditioning, the BES system can also compensate the load reactive and harmonic powers. Thus the current waveform and the power factor on the utility grid are much improved. The modelling, design and implementation of the proposed controllers are described and some experimental results are given to show the performance of this BES system.

Electrical energy management in small, and medium size industries

Abstract: There is a general awareness of the opportunities for reducing the cost of electricity consumption in industry, but the progress in implementation has been slow and stagnant, particularly in the small and medium size industries Part of the reason for the slow progress is lack of information on methodologies for the electrical energy management in industries The paper discusses common aspects of electrical energy management in small and medium size industries It contains the finding and the analysis of the results obtained from the electrical energy audit program which is done in various industries The analyses are focused on the load management, power factor management, transformers analysis and motor losses management >

Integrating thermal energy storage in power plants

Abstract: This article describes a system that stores thermal energy in a natural gas-fired cogeneration facility uses a gas turbine, a heat recovery salt heater, and salt-heated steam generator. The National Energy Strategy forecast estimates that 200,000 megawatts-electric (MWe) of new electric-generating capacity will need to be added to the US nationally by the year 2010. Approximately 40 percent of this new generating capacity will be for peak or intermediate loads, with the rest providing continuous baseload power generation. Natural gas-fired combustion turbine technologies, including cogeneration, combined-cycle, and integrated gasification combined-cycle power plants, are becoming the generating options of choice because of their flexibility, relatively low capital cost, reduced environmental impact, and increasing thermal efficiency. Thermal energy storage (TES) for utility applications includes a range of technologies that can further improve the efficiency, flexibility, and economics of gas turbine options.

Canadian national power quality survey

Abstract: An increasing number of polluting electrical and electronic loads are being connected to today's electrical distribution systems. With this comes the potential for increased customer complaints about 'alleged' power supply quality problems affecting the performance of 'sensitive' electronic equipment. The Canadian Electrical Association (CEA) is taking a proactive approach to this problem and has started a two year survey of power quality across Canada. The authors present a detailed discussion of what data is being captured for this survey, new techniques being used to analyze the data, and how the results are being displayed to show a comprehensive, high-level summary of the power quality measured at each sample site. The authors also discuss the technical requirements for the power line monitors that were chosen, and the rationale behind the monitor thresholds being used for this survey. A sample survey site report is also shown and discussed.

Bulalo field, Philippines: Reservoir modeling for prediction of limits to sustainable generation

Abstract: The Bulalo geothermal field, located in Laguna province, Philippines, supplies 12% of the electricity on the island of Luzon. The first 110 MWe power plant was on line May 1979; current 330 MWe (gross) installed capacity was reached in 1984. Since then, the field has operated at an average plant factor of 76%. The National Power Corporation plans to add 40 MWe base load and 40 MWe standby in 1995. A numerical simulation model for the Bulalo field has been created that matches historic pressure changes, enthalpy and steam flash trends and cumulative steam production. Gravity modeling provided independent verification of mass balances and time rate of change of liquid desaturation in the rock matrix. Gravity modeling, in conjunction with reservoir simulation provides a means of predicting matrix dry out and the time to limiting conditions for sustainable levelized steam deliverability and power generation.

Energy conditioning converter

Abstract: The paper describes a power electronic convertor for optimal distribution and quality improvement of electrical energy in power networks. The power converter can provide, simultaneously, compensation of slow fluctuations of active power (load levelling), load balancing, as well as the elimination of stochastic distortions and reactive power. >

Energy conservation with chilled-water storage

Abstract: Thermal energy storage (TES) is widely recognized as a demand-side management technology for shifting cooling electrical demand from peak daytime periods to off-peak nighttime and weekend periods when utilities have reserve generating capacity. TES has enabled users to significantly reduce their electricity costs by reducing peak demand and taking advantage of lower off-peak usage rates, often with large utility incentive payments and sometimes with reduced capital costs. It has also enabled utilities to reduce peaks and fill valleys, thereby improving system load factors, reducing reliance on peaking units, increasing utilization of base load units and postponing the construction of additional generating units. Because TES has been so strongly categorized as a demand-shifting technology, its potential for energy conservation has received little recognition. And, certainly, there are many existing TES systems that use more electricity than conventional cooling systems and are beneficial only for shifting demand. However, recent advances in the technology have produced more efficient and better integrated TES systems that use less electricity and natural gas than conventional cooling/heating systems. To apprise engineers of thermal energy storage's potential for energy conservation, this article will study the design and operation of a TES system in one industrial retrofit application.

Development of advanced load conditioner connectible with photovoltaic cells

Abstract: A 'load conditioner' is defined as a small-scale battery energy storage system, which stores night time electricity and provides power for daytime demand. A 5 kW advanced load conditioner has been developed, which is applicable to a single-phase three-wire power line and is connectible with photovoltaic cells. The load conditioner can transfer the excess photovoltaic power either to the power line or to the storage battery. It can not only guarantee a high-quality interconnection with a power line by means of an active filter but can also be a high reliability uninterruptible power supply to specific loads. >

Voltage and reactive power distribution factors for line, transformer and generator outage studies

Abstract: This paper reports the development of a fast and efficient method to calculate a new set of voltage and reactive power distribution factors for line, transformer and generator outage studies. The new distribution factors have been derived using base load flow results and an efficient method exploiting the property of Newton-Raphson load flow (NRLF) Jacobian available at the end of a base load flow. The factors can be used for rapid computation of the post-outage bus voltage magnitudes and outputs of reactive power sources.

Least-cost planning in developing countries

Abstract: The electric power industry in developing countries, as in the rest of the world, faces least-cost planning problems characterized by a range of supply-side and demand-side options, multiple conflicting objectives, and pervasive uncertainty. Two recent least-cost planning studies were sponsored by the World Bank and carried out by utilities in Hungary and Costa Rica. Although the circumstances in the two countries are very different, and the studies were carried out by different teams, they reached similar conclusions. First, both studies concluded that availability of capital was a key ingredient in developing least-cost plans. This conclusion is particularly important for developing countries since their capital requirements for power supply expansion are huge, thus indicating the need for seekin new ways of mobilizing financial resources and the adoption of policies to encourage more efficient production and end use of power. Second, both utilities were able to do thorough multi-objective and risk analyses. Third, both studies found that the multi-objective and risk analyses led to some conclusions which differed from those reached by traditional optimization, and included some surprises. In particular, the Hungarian analysis pointed to more gas turbine capacity than was previously envisaged, and found that electricity imports were an attractive option.more » Implementation of load management was also a winner, at least as a hedge. The Costa Rican analysis concluded that varying the power supply mix was not desireable: the utility should continue its reliance on hydro, with minor additions of thermal capacity, but eschewing baseload coal or heavy geothermal development, and with diesels preferred to gas turbines.« less

Planning distribution systems considering thermal capacities of power cables

Abstract: Today, load forecasts urge the planner of electrical power supply networks to take extension measures according to common planning practice. To postpone or even avoid those decisions which are often based on too restrictive assumptions or too simple models is the main target of this study. This can lead to enormous savings in investment cost. Looking at the ageing process of energy cables in medium voltage (MV) networks possible transmission reserves are pointed out which are of main practical importance. The potential of these reserves can be quantified by using the authors' method to calculate the possible thermal cable capacity.

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.

Optimizing the power system impacts of demand-side management

Abstract: With an increasing emphasis on demand-side management (DSM) as an alternative to more traditional power system expansion methods, utility planners are required to conduct more comprehensive analyses in order to achieve a satisfactory integration of supply-side and demand-side technologies. DSM impacts are typically manifested in varying degrees at each level of the power system. Thus, the complexity of optimizing an electrical power system is increased under the DSM option. The authors discuss the fundamental issues of DSM impacts, particularly with respect to the transmission and distribution portions of the power system. The nature of the characteristic differences of the customer classes, the importance of DSM market penetration, and the utilization of system reconfiguration are emphasized with regard to achieving maximum system benefits.

Simulation analysis and optimization of a finite-time gas power plant

Abstract: The power output of a simple, finite-time closed gas-turbine power plant is modeled and analyzed. The model adopted is a reversible Brayton cycle coupled to a heat source and a heat sink by heat transfer. Both the heat source and the heat sink may have either finite or infinite heat-capacity rates. A mathematical expression is derived for the power output of the irreversible power plant. The maximum power output of the power plant is found by computer simulation. The maximum bound provides the basis for designing a real closed gas-turbine power plant and for a performance comparison with existing power plants

Electricity from coal and gas-a cost comparison

Abstract: The EC Large Combustion Plant Directive requires the UK power generating companies to reduce emissions of SO2 by 60% by the year 2003 (based on 1980 SO2 emission levels). At present, coal provides approximately 60% of the UK power generating capacity and has a high sulphur content relative to other major sources of electrical energy in the UK. While both oil and orimulsion can potentially emit large quantities of SO2 neither is currently in widespread use within the UK power generation sector. Gas-fired power stations emit negligible quantities of SO2 if burning sweet (or treated) gas. Emissions of SO2 from nuclear and hydroelectricity generating capacity are negligible. Coal combustion in power stations is therefore the largest source of SO2 in the UK.

The combination of once-through Fischer-Tropsch with baseload IGCC Technology

Abstract: Integrated Gasification Combined Cycle (IGCC) is an emerging technology for electric power generation from coal with minimum impact on the environment. Power is generated efficiently by a combination of syngas-driven gas turbines and steam turbines. Studies have shown that the capital cost of an IGCC plant is relatively high when compared to a natural-gas-fired combined cycle plant while its variable operating costs are comparatively low because coal is a lower priced fuel. Favorable IGCC economics thus require high capacity utilization as well as the high availability and reliability normally required for utility industry power plans. A base load plant will meet these criteria if adequate attention is paid to gasifier reliability. In a study sponsored by Florida Power and Light Company (FPL) and the Electric Power Research Institute (EPRI), Bechtel investigated the addition of an operating spare gasification train with methanol co-production from the syngas in order to improve the reliability of a base load electric power plant. As shown, the net result was an improved plant availability along with the co-production of a valuable by-product which paid for the addition of the spare gasifier. Co-production of hydrocarbons via Fischer-Tropsch (F-T) technology is a logical alternative to methanol co-production becausemore » it can offer the similar synergistic effects on the power plant similar to the methanol co-production scheme. Bechtel is currently carrying out a Baseline Design/Economics Study for Department of Energy, Pittsburgh Energy Technology Center (DOE/PETC) on indirect coal liquefaction using advanced F-T technology.« less

Effect of operational parameters on reliability of composite using sequential simulation

Abstract: Rcliability assessments are a n integral part of power system studies in order to assist decisions to improvc or maintain quality and adequacy of tlic systcm. The studics reportcd in this paper arc the application of models bctscd on Monte Carlo simulation for assessing the reliability ol composite gcncration atid trmsmission systen~s containing mixed hydro tlietrnal gencrating uiiiLs. The primary objective of this paper is to perform a rangc of scnsitivity analyses regarding the opcrational and nianagcmcnt paratiictcrs of such systems using tlic sequcntial simulation approacli. Tlicse are achieved using the New Brunswick Power System (NIWS) [ I ] as tlic liytlro thermal conipositc system under study. This study is the extension of tlie work reported earlier [2]. It is Iio~xccl that it will lead cvcntually to an improved reprcsentation aid undcrstandirig of tlic system by taking into account tlic randomness associated with eiiergy limitation of tlic hydro units. INTRODUCTION Assessing the required anioimt of gcncratioii capacity to ensure adequacy of supply is an i n ip r t a i i t considcrntion in both the planning and tlie opcration stages of a powcr systcm. This adequacy assessmcnt can be clotie, in part, by using rcliability evaluation tccliniques. Tlicre are two basic approachcs [3-51; die :irialytical approach and the stocliastic simulation approach. An analytical nietliod uses basic matliematical models anti gaicr:illy enumcratcs and combines the probabilities and frequciicics of systcni states to calculate ttic reliability indices but is usually restricted to the evaluation of expcctcd valucs only and somctinics to a limited range of system paranetcrs. On tlic other liarid simulation tccliniqucs, commonly known cis Moritc Carlo simulation, trcat tlic problctii as a serics of 'real' cxpcrimcnts. Outcome oC tlicsc cxpcrimcnls dci)cnd on the operating cliaractcristics of the comporicnt.. and of tlie systcm. Monte Carlo sinnilations c m bc citlicr non-scqucntial (random) or sequential. Tlic sequcntial siniulation approacli is particularly suitablc wlicri tlic system states at ;my given point in time are partially detcmiincd by the historical cvolution of Uic systcm. This is often tlic case with hydro elccttic systcnis because the availablc power and energy are dcpcndcnt on w:itcr flows, opcrational policies and historical evolution of load. Tlic tncrits o l making planning decisions only on cxpcctctl v:ilues is vcry qucstionnblc. There is frequently a nccd to know tlic likcly raiigc of rcliability indices, tlic likelihood of ccrtairi valucs bcing cxcccdcd, anti otlicr similar paranictcrs. Tlicsc can only bc asscsscd from a knowledge of the distribution dint is wrapped aroutid tlic cxpcctcd value, and this is easily accomplished using scqueritial appro:icli t~ccausc it travcrscs tlirough time chronologically. 'I'licrcforc, this approach c m rcprcscnt, not o d y most contingencies arid opcrating cliaractcristics inl~crcnt in the system, but also provides the most coti~~~r~licrisivc r:uige or reliability indices. Tlic COMPositc systcin Asscssriicnt using Scquciiti.il Simulation (COMPASS) program is I):isctl on :i scclitcdal Montc Carlo siinulatioii tccliriiquc 1i:ivirrg options t o inclutlc all tlie~n~:il, all Paper APT IS-312 iiivitcd for p~cseiitntioii at tlie IEEE/NTUA Atliciis Power Tech C o h m n c e : "Planning, Operation and Coiitiol of Today's Electric Power Systcms", Athens, Greece, Sept. 5-S, 1993. liydro or mixed hydro thermal generating units at the HL I or HL I1 hicrarcliical levels [GI. The models used are described in detail in [681. Tlic main cmpliasis in this paper is to relate the effect that various opcrational parameters and water tnuiagement constraints have on the behaviour o l mixed hydro l l v " composite systems. This is acllieved by pcrforniing sensitivity analyses using the COMPASS niodcls on tlic New Brunswick Power System (NBPS) [ 11. Previously 121 all three liydro units of tlie NBPS are modelled as energy abundant units but now a realistic reservoir exploitation scheme is included IO model tliem. IIYDRO SYSTEhl MODELLING Tlie generating output in a hydro system depends on the past history of water inflows into the rcscrvoirs, tlie operating and water managenlent policies and the evolution of the load up to the instant bcing analysed. Operating deficiencies in these systems may bc caused by an energy deficit due to limits on tlic water storage of the hydro plan& or by power deficit due to limits on the maximum capacity of the hydro plnnts or by a forced outage of a generating unit. All tlircc hydro generating units of tlie NnPS are assumed to be 100% rcliablc in Ihese studies but a forced outage and repair modcl c" also lx uscd. The inflow into a reservoir depends upon the amount the water released from upstreani reservoirs, tributary inflows and water losses in tlie incoming flows, which in turn is determined by tlic amount of rainfall and any gcographical connections between rivers. All tliree reservoirs in h is particular study are considcrcd to belong to tlic same hydrological area. However it should be noted that there are no conceptual limitations on using any multiple number of rivcr arr:uigcments and my number of Iiydrologicd area in COMPASS [G81. It can also simulatc any numbcr of pumped storage plants. The conccptual models of the hydro plant including water inflows, reservoirs and tlie turbine-generator are described in detail in 16-81. Dilfcrcnt operating and water management policies can be followed in a mixed hydro dicmial generating system. The principle for operating an energy limited system is to use die available energy in tlic best possible way during the period in which it is available. Tlic operating policies determine what tliernial generation atid what liytlro plants should be committed. In HL I1 evaluation tlie trnsniission systcm constraints arc taken into account and conscqucntly rcdispatcli atid load shedding is ncedcd if overloads aplxar in any linc. ~l'liesc algoritluns are also part of the opcrating policies. An opcratitig policy can be based on eitlier a pure safety policy wlicrc ottly system reliability is of interest or a mixcd cconoriiy-sdcty p l i c y when reliability as well as running costs are considered 191. 'Ilic mixed economy-safety policy is applied in order tliat tlic availablc hydro gcncration is uscd not only to reduce loss-oflo:d but also to substitute tlicriiial gcticration on economic grounds. ' l l c opmiting policy niodcl of COMPASS recognises tlic factors nCfccting die actual dispntcli of gciicrating units, e.g. fuel cost, cricrgy stiitc of rcscrvoirs, rcstriction in use of water. energy uscd to pitnip watcr mid pcrlornis dispatcli in tlie following order: TFIA (tlicrnial base gcncration) lIYA (hydro avoids spillage) THB (thermal economic gencration) MY11 (hydro economic gcncration) TIIC (tlicrrnal expnsive generation) TI ID (thcrmal peaking generation) IIYC (Iiydro emergcncy gcncration)

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.

Conjunctive Operation of Hydroelectric and Thermal Power Plants

Abstract: A dynamic programming model has been reviewed and extended for the optimization of a mixed hydro-thermal power system consisting of only one reservoir, several run-of-the-river type and thermal power plants. The objective function of the model is taken as maximization of on peak firm energy generation on an annual basis treating the output of the run-of-the-river type and thermal power plants as a parameter. This model can easily handle the complexity caused by presence of the thermal and run-of-the-river type power plants without creating any difficulty in computer time and space. Comparison of combined and separate operation of reservoir with run-of-the-river type and thermal power plants shows that combined operation is advantageous. In this study the model is used to determine the optimal operational policy of Kulekhani reservoir and corresponding performance of the existing power generation facilities in Nepal.