AckermannTh. (ed) Wind Power in Power Systems

Подождите немного. Документ загружается.

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 321 – [299–330/32]

20.12.2004 7:46PM

Thus a large variety of features are needed to cover the numerical modelling needs in all

contexts. No single numerical model is able to provide all features, as they often are in

conflict with each other in terms of modelling requirements. This survey of modelling

requirements is based on a review of relevant studies that was carried out as part of an

earlier study (reported by Lundsager et al., 2001).

14.6.1 Requirements and applications

The requirements of the numerical models de pend on the actual application of the

modelling. Many factors influence the layout of a numerical model, and the main

factors include:

the objectives of the simulations;

the time scale of the modelling;

the modelling princi ple (deterministic or probabilistic);

representation of the technical and economic scenarios;

system configurations, including dispersed compared with single system configur-

ations.

The objectives of the simulations depend on whether the simulations are done in a

feasibility study as part of the decision process or as part of the design process. Objectives

may concern:

screening or optimisation of possible system or grid configurations;

the overall annual performance of selected configurations;

supervisory control, including scheduling an d dispatch of generating units ;

grid modelling, stability or load flow.

Several time scales of system modelling are used, depending on the context and purpose

of the simulation. They may focus on:

transient analysis of electrical transients due to switching, or certain power quality

measures: typically a few seconds with a time step of less than 0.001 s;

dynamic analysis of machine dynamics, power quality or grid stability over specific

system state changes: typically around 1 minute with time steps around 0.01 s;

dispatch analysis of supervisory control, including diesel dispatch: typically a few

minutes to an hour at time steps of 0.1 s to 1 s;

logistic analysis of power flows and seasonal and annual energy production: days,

weeks, months, seasons or one year at time steps 10 min to 1 h;

screening models for logistic analysis that give an overall assessment of the perform-

ance of a system, wi thout going into very much detail of the specifics in the operation

of the system.

Probabilistic modelling, based on probability distributions such as load duration

curves or wind speed probability curves, can work directly with the outputs of typical

utility statistics and resul ts from wind resource assessment models such as WAsP

Wind Power in Power Systems 321

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 322 – [299–330/32]

20.12.2004 7:46PM

(Mortensen et al., 1993) but they cannot readily represent ‘memory’ effects such as

energy storage, diesel dispatch strategies and deferrable loads. Time series simulation

can do that, but to obtain the same statistical significance as probabilistic models Monte

Carlo techniques ideally should be applied.

Most models represent technical performance by one year’s performance measures

(fuel savings and so on) and use an economic lifecycle analysis to establish the economic

indicators. This way the technical developments and/or extensions to the system during

its lifetime are neglected. This is in fact inadequate to give a realistic representation of

the (often) rapid development of isolated systems during the entire technical and

economic life of the project, which may be up to 20 years.

A realistic representation of both system configuration and control strategy in the

modelling is essential for a reliable and accurate prediction of system performance.

Several techniques have been applied to facilitate the flexible modelling of system

configuration and connectivity, but the flexible modelling of supervisory control strat-

egy appears to be even more challenging (Pereira et al., 1999).

For dispersed systems, the electric grid becomes part of the system. Deterministic load

flow analysis is well established, but probabilistic load flow modelling is more in line

with the stochastic nature of wind and loads in isolated systems and the associated

probabilistic power quality measures (Bindner and Lundsager, 1994).

Actual grid stability analysis requir es real dynamic electromechanical models, and

such analysis is frequently outside the scope of isolated system analysis.

14.6.2 Some numerical models for isolated systems

In this section a number of numerical modelling techniques and models are reviewed

and, although we do not claim the review is complete, we focus on models for wind

and wind–diesel applications that are used for the assessment of the technical–economic

performance of the system (for a further review, see Baring-Gould et al., 2003; Clausen

et al., 2001; Lundsager et al., 2001). Selected models are briefly described in Table 14.5.

Some of the models are not publicly available, but the references provide details of

valuable experience with modelling concepts and techniques.

Numerical models are available that can han dle practically any requirement for

theoretical modelling of isolated power system projects. Thus the availability of models

is not a limiting factor for development, but the extent of the efforts involved in applying

a complete set of modelling tools for a given isolated community situation may be

considerable if not prohibitive.

14.7 Application Issues

One of the major drivers for retrofitting diesel power systems with renewable technology

is the relatively high cost of producing power with diesel engines. However, a number of

issues have strong influence on the options to be chosen and the success of their

implementation.

322 Isolated Systems

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 323 – [299–330/32]

20.12.2004 7:46PM

Table 14.5 Overview of computer models for technical–economical assessment

Model Description Source Availability

HOMER HOMER is a fast and comprehensive

off-grid and distributed micro-power

system screening and configuration

optimization model. It is widely used and

provides a user friendly interface. This

model is the state-of-the-art for initial

system conceptual analysis.

Lilienthal, Flowers

and Rossmann, 1995

Publicly available

from NREL,

www.nrel.gov/homer

INSEL INSEL offers almost unlimited flexibility

in specifying system configurations by

allowing the user to specify the

connectivity on a component level. It is

intended as an out-of-house-model.

Renewable Energy

Group, 1993

Not publicly

available

HYBRID2 HYBRID2 is the state-of-the-art time

series model for prediction of technical–

economical performance of hybrid wind–

photovoltaic systems. It offers very high

flexibility in specifying the connectivity of

systems and is quite widely used.

Baring-Gould, 1996 Publicly available

from the University

of Massachusetts,

www.ecs.umass.edu/

mie/labs/rer

SIMENERG SIMENERG is the only model so far with

a very high degree of flexibility in the

control and dispatch strategy, using a

‘market square’ approach, where the

economically optimal subset of power

sources that satisfy the power demand is

dispatched in each time step.

Briozzo et al., 1996

WINSYS WINSYS is a spreadsheet (QPW) based

model implementing probabilistic

representations of resources and demands.

WINSYS incorporates the anticipated

technical expansions during its lifetime in

the technical performance measures,

combined with a traditional economic

lifecycle cost assessment. Thus WINSYS

presents a more realistic lifecycle cost

analysis than most other models.

Hansen and Tande,

1994

Not commercially

available

WDLTOOLS WDLTOOLS was developed by

Engineering Design Tools for Wind Diesel

Systems and is a package containing seven

European logistic models: SOMES (The

Netherlands), VINDEC (Norway),

WDILOG (Denmark), RALMOD (UK)

and TKKMOD (Finland). Although

somewhat outdated it also includes the

modular electromechanical model

JODYMOD.

Infield et al., 1994 Not publicly

available

RPM-Sim RPM-Sim is a model that uses the

VisSim

visual environment and allows

for the dynamic analysis of wind, PV and

diesel systems. Researchers at NREL’s

National Wind Technology Center

developed the model.

Bialasiewicz et al.,

2001

Not publicly

available

(continued overleaf)

Wind Power in Power Systems 323

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 324 – [299–330/32]

20.12.2004 7:46PM

14.7.1 Cost of energy and economics

The cost of electricity in isolated systems, where existing power supply is typically from

diesel power plants, varies over a very wide range, from a low of US$0.20 per kWh to a

high of over US$1.00 per kWh.

Clearly, the cost of electricity in existing isolated systems is typically many times

higher than in large utility grids, where net production cost of electricity is of the order

US$0.04 per kWh. Additionally, the cost for stora ge of diesel fuel in areas that may

receive limited fuel shipments each year may also increase the c ost of providing power to

remote areas (Clausen et al., 2001).

The cost of electricity from grid-connected wind turbines has decreased to approach-

ing US$0.04 per kWh in large grids and twice to three times this amount for smaller

turbines fit for rural applications. The main parameter influencing the COE from wind

turbines of a given size is the annual average wind speed.

Electricity production costs from wind–diesel systems are not well documented, and they

cover a very wide range. Furthermore, COE from a wind–diesel system may be difficult to

ascertain precisely, as the task may be outside the scope of small-scale projects. Therefore,

the economic viability of a system will often be assessed by comparing the COE from the

wind turbine (including costs of any support technology) with the avoided costs of fuel and

diesel service in the existing diesel system. In the case of a retrofit installation of an

Table 14.5 (continued)

Model Description Source Availability

MatLAB This software uses Simulink

and the

MatLAB

Power System Blockset to

analyse the dynamic response of wind–

diesel applications. It was developed by

the Hydro-Quebec Research Institute

— Available through

MathWorks, http://

www.mathworks.com/

PROLOAD PROLOAD is a probabilistic load flow

analysis code, using Monte Carlo

techniques, developed in cooperation with

an electrical utility for the dimensioning of

distribution systems with wind turbines.

Tande et al., 1999 Not publicly available

RETScreen RETScreen is a spreadsheet (Microsoft

Excel) based analysis and evaluation tool

for the assessment of the cost-effectiveness

of potential projects with renewable

energy technologies. The software

package consists of a series of worksheets

with a standardised layout as well as an

online manual and a weather and cost

database. The tool is developed by

CEDRL.

RETScreen, 2000 Publicly available

from the CEDRL

website at

www.retscreen.net

Note: CEDRL ¼CANMET Energy Diversification Research Laboratory; NREL ¼ National

Renewable Energy Laboratory (USA).

324 Isolated Systems

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 325 – [299–330/32]

20.12.2004 7:46PM

additional wind turbine in an existing wind–diesel system, this may be a fair assessment;

however, in the planning phase of a new isolated system the comparison should be based

on total cost of electricity including the capital cost of the alternatives analysed.

14.7.2 Consumer demands in isolated communities

From a consumer’s point of view, an isolated power system with wind power should

satisfy the same demands as conventional power system solut ions. Wind power should,

as such, be treated as just another option in accordance with priorities of relevant

policies and plans. Since wind energy is resource-driven, in order to be able to assess

wind power in comparison with conventional options such as diesel, a supplementary set

of information describing the community will most often be necessary.

The feasibility of wind power in small isolated power systems may be particularly

sensitive to issues of grid interconnection costs, electricity demand development and

diurnal consumer patterns, whether the system supplies electricity 24 hours a day or less.

Furthermore, costs for consultants for special studies or power system design add to the

investment cost, which may be unacceptable for small communities.

Using Egypt as an example, it was attempted in a study (reported by Lundsager et al.,

2001) to acquire a general overview of the potential types of systems in which wind

power could be an option. Table 14.6 shows an overview, splitting the commun ities in

three categories.

Hurghada in Egypt has operated as a medium to high wind energy penetration system

since 1998, and it has provided demonstration for Egypt of this technology.

14.7.3 Standards, guidelines and project development approaches

A major key to success is the development and application of proper guidelines and

standards for these systems. As a market develops, so does the need for de veloped

standards and guidelines for system design, implementation and commissioning.

The difference between standards and guidelines are illustrated by the two types of

Table 14.6 Overview of isolated power systems in Egypt

Category Description Estimated number

in Egypt

1 Micro grids currently not electrified or nongrid communities

that get electricity from buying or charging batteries or

from individual household systems

>100

2 Village power and island power systems, presently powered

by diesel systems of sizes between 50–1000 kW

3 Island and large interconnected power systems – isolated or

end-of-line systems with 1–150 MW installed capacity of diesel

or gas turbine supplied loads

5–10

Source: Lundsager et al., 2001, reproduced with permission.

Wind Power in Power Systems 325

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 326 – [299–330/32]

20.12.2004 7:46PM

documents that are now being developed in the framework of the International Electro-

technical Commission (IEC), described below.

Standards deal with the specific technical elements of energy (DRE) systems and are

the responsibility of individual technical committees in the national and international

standardisation framework that include the IEC, the Comite

Europe

en de Normal-

isation Electrotechnique (CENELEC) and other bodies. The standards are unique, and

all project implementation guidelines should refer to one and the same set of renewable

energy system standards. This set-up is adopted in the development of the IEC/publicly

available specification (PAS) guidelines IEC PAS 62111 (IEC, 1999) for small DRE

systems for rural electrification in third world countries. This document is currently

being developed into an IEC guideline under the title of ‘Recommendations for Small

Renewable Energy and Hybrid Systems for Rural Electrification’, IEC 62257 (IEC,

0.000). The development of this standard, however, focuses on smaller power systems,

typically under 50 kW total output power, and is thus not applicable to larger wind–

diesel applications.

In ‘Isolated Systems with Wind Power – An Implementation Guideline’, by Clausen

et al. (2001), a unified and generally applicable approach to project implementation is

attempted to support a fair assessment of the technical and economical feasibility of

isolated power supply systems with wind energy.

General guidelines and checklists on which information and data are needed to carry

out a project feasibility analysis are presented as wel l as guidelines of how to carry out

the project feasibility study and environmental analysis. The main process detailed by

Clausen et al. (2001) includes:

fact finding;

project feasibility analysis;

environmental impact analysis;

institutional and legal framework;

financing;

implementation.

At the initial stage of development this can be summarised in an appro ach where the

following are combined in the project preparation:

site evaluation based on resource assessment modelling;

technical assessments based on logistic modelling techniques;

economic evaluations based on lifecycle costing principles.

These three basically computational techniques should be coupled to a thorough ana-

lysis of nontechnical (institutional) issues.

As is commonly stated, the key to success in the application of wind power in isolated

power supply systems is proper project preparation. In this chapter we have described

some of the factors related specifically to isolated systems; other facto rs, such as wind

resource assessment, wind turbine characteristics and grid integration issues, are dealt

with in other chapters of this book.

326 Isolated Systems

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 327 – [299–330/32]

20.12.2004 7:46PM

14.8 Conclusions and Recommendations

A number of issues have been identified that should be considered when developing a

wind power project as part of an isolated power system, be it a small system of a few

kilowatts or a large megawatt-size system. A successful project will often have the

following characteristics:

It will use updated versions of relevant international standards, including the that for

decentralised power systems with renewable energies now in progress within the IEC.

Best practice guidelines for project implementation will be applied, including common

references and relevant experience from recent projects.

The wind power project in the isolated system in question will be part of a concerted

action in a national and international programme rather than an individual project.

The wind power technology applied in a small to medium-size system will follow

simple and proven approaches, for instance by repeating and/or scaling pilot and

demonstration systems with positive track records, which may have been developed

from filtering down from large-scale systems any technological achievements adapt-

able to smaller systems.

Small systems will be developed to apply rugged technology suitable for remote

communities.

No experimental systems will be installed at rural remote communities unless pre-

viously thoroughly tested and documented at test benches dedicated to serve as

experimental facilities. Any pilot or proof-of-concept system should be implemented

only with the consensual understudying that the system will likely need higher levels

of support for the life of the system, not only the life of the expected research project.

Ownership will be well defined, with a built-in interest identified to ensure long-term

interest and funding of operation, maintenance and reinvestments when needed.

An organisation will be established with the necessary capacity and capability for

implementation, operation and maintenance, preferably including the backup from a

relevant national or regional knowledge centre.

A sufficiently detailed feasib ility study will have been performed.

Modelling assumptions, input data and methodology applied for the feasibility study

and system design will reflect the true hardware reality for the types of systems in

question.

The technical capacity to design, build and operate isolated power systems with a high

penetration of wind power exists, but the mature product and the market have not yet

met. Nevertheless, there is today an industry offering small wind turbines (10–300 kW)

and associated equipment for hybrid system applications with a long-term commitment.

This indicates a belief that a market is emerging and that interest from some large wind

turbine manufacturers can be expected.

However, the main barrier is the lack of a positive, well-documented track record for

isolated systems with wind power. Some of this has been a result of early technical

failures in complex systems but, more generally, the technology has yet to supply

enough successful examples to be accepted by the mainstream markets. Therefore, in

Wind Power in Power Systems 327

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 328 – [299–330/32]

20.12.2004 7:46PM

addition to, of course, ensuring that any system implemented in an isolated community

works reliably and economically, it is important also to ensure that proper follow-up

and monitoring of system performance is carried out. Only then will a proper and well-

documented track record be established. Additionally, in order for this potential market

to develop, a simple approach should be found that can be applied at low cost and at a

risk comparable to the risk involved when designing a diesel-powered system.

The above recommendations are seen as steps that could open and extend access to

electricity for the benefit of, for example, small rural communities but, in a broader

scope, the process could lead in the direction of an increased use of wind power in the

whole range of isolated power systems from a few kilowatts to several megawatts.

References

[1] Allderdice, A., Rogers, J. H. (2000) ‘Renewable Energy for Microenterprise’, booklet, Report BK-500-

26188, National Renewable Energy Laboratory, Golden, Co.

[2] Baring-Gould, E. I. (1996) ‘Hybrid2: The Hybrid System Simulation Model’, Report TP-440-21272,

National Renewable Energy Laboratory, Golden, Co.

[3] Baring-Gould, E. I., Castillo, J. Flowers, L. (2003) ‘The Regional Replication of Hybrid Power Systems in

Rural Chile’, in Proceedings of the 2003 AWEA Conference, Austin, TX, May, 2003, American Wind

Energy Association.

[4] Baring-Gould, E. I., Barley, C. D. Drouilhet, S., Flowers, L., Jimenez T., Lilienthal, P., Weingart, J.

(1997). ‘Diesel Plant Retrofitting Options to Enhance Decentralized Electricity Supply in Indonesia’, in

Proceedings of the 1997 AWEA Conference, Austin, TX, June 1997, American Wind Energy Association.

[5] Baring-Gould, E. I., Flowers, L., Lundsager, P., Mott, L., Shirazi, M., Zimmermann, J. (2003) ‘World

Status of Wind Diesel Applications’, in Proceedings of the 2003 AWEA Conference, Austin, TX, American

Wind Energy Association.

[6] Baring-Gould, E. I., Newcomb, C., Corbus, D., Kalidas, R. (2001) ‘Field Performance of Hybrid Power

Systems’, Report CP-500-30566, National Renewable Energy Laboratory, Golden, Co.

[7] Bialasiewicz, J. T., Muljadi, E., Nix, R. G., Drouilhet, S. (2001) ‘Renewable Energy Power System

Modular Simulator: RPM-SIM User’s Guide (Supersedes October 1999)’, Report TP-500-29721,

National Renewable Energy Laboratory, Golden, Co.

[8] Bindner, H., Lundsager, P. (1994) ‘On Power Quality Measures for Wind–Diesel Systems: A Conceptual

Framework and a Case Study’, paper presented at European Wind Energy Conference, Thessaloniki,

Greece, June 1994.

[9] Briozzo, C., Casaravilla, G., Chaer, R., Oliver, J. P. (1996) ‘SIMENERG: The Design of Autonomous

Systems’, pp. 2070–2073. in Proceedings of the World Renewable Energy Congress III, Reading, UK, 11–16

September 1994, pp. 2070–7073.

[10] Clausen, N-E., Bindner, H., Frandsen, S., Hansen, J.C., Hansen, L.H., Lundsager, P. (2001) ‘Isolated

Systems with Wind Power – An Implementation Guideline’, publication R-1257 (EN), June 2001, Risø

National Laboratory, Roshilde, Denmark.

[11] Corbus, D., Newcomb, C., Baring-Gould, I., Friedly, S. (2002) ‘Battery Voltage Stability Effects on Small

Wind Turbine Energy Capture’, preprint, Report CP-500-32511, National Renewable Energy Labora-

tory, Golden, Co.

[12] Cotrell, J., Pratt, W. (2003) ‘Modeling the Feasibility of Using Fuel Cells and Hydrogen Internal

Combustion Engines in Remote Renewable Energy Systems’, Report TP-500-34648, National Renewable

Energy Laboratory, Golden, Co.

[13] Cramer, G., Reekers, J., Rothert, M., Wollny, M. (2003) ‘The Future of Village Electrification: More

than Two Years of Experience with AC-coupled Hybrid Systems’, in Proceedings of the 2nd European PV

Hybrid and Mini-Grid Conference, Kassel, Germany, pp. 145–150, Boxer, Germany.

[14] DOE/AWEA/CanWEA (2002) Proceedings of the 2002 DOE/AWEA/CanWEA Wind–Diesel Workshop,

http://www.eere.energy.gov/windpoweringamerica/wkshp_2002_wind_diesel.html.

328 Isolated Systems

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 329 – [299–330/32]

20.12.2004 7:46PM

[15] Engler, A., Hardt, C., Bechtel, N., Rothert, M. (2003) ‘Next Generation of AC Coupled Hybrid Systems:

3 Phase Paralled Operation of Grid Forming Battery Inverters’, in Proceedings of the 2nd European PV

Hybrid and Mini-Grid Conference, Kassel, Germany, pp. 85–90, Boxer, Germany.

[16] Hansen, J. C., Tande, J. O. G. (1994) ‘High Wind Energy Penetration Systems Planning’, paper presented

at the European Wind Energy Conference, Thessaloniki, Greece, June 1994.

[17] Hansen, J. C., Lundsager, P., Bindner, H., Hansen, L., Frandsen, S. (1999) ‘Keys to Success for Wind

Power in Isolated Power Systems’, paper presented at the European Wind Energy Conference, Nice,

France, March 1999.

[18] Hansen, L. H., Helle L., Blaabjerg F., Ritchie E., Munk-Nielsen S., Bindner, H., Sørensen, P., Bak-Jensen, B.

(2001) ‘Conceptual survey of Generators and Power Electronics for Wind Turbines’, publication R-1205

(EN), Risø National Laboratory, Roskilde, Denmark.

[19] Hunter, R., Elliot, G. (Eds) (1994) Wind–Diesel Systems, Cambridge University Press, Cambridge, UK.

[20] IEC (International Electrotechnical Committee) (1999) ‘Publicly Available Specifications on ‘‘Decentra-

lised Renewable Energy Systems’’ (DRES)’, IEC PAS 62111, July 1999, IEC, Geneva, Switzerland.

[21] IEC (International Electrotechnical Committee) (in development) ‘Recommendations for Small Renew-

able Energy and Hybrid Systems for Rural Electrification’, IEC 62257, Geneva, Switzerland.

[22] Infield, D., Scotney, A., Lundsager, P., Bindner, H., Pierik, J., Uhlen, K., Toftevaag, T., Falchetta, M.,

Manninen, L., Dijk, V. V. (1994) ‘WDLTools – Engineering Design Tools for Wind Diesel Systems’,

Energy Research Unit, Rutherford Appleton Laboratory.

[23] Jimenez, A. C., Lawand, T. (2000) ‘Renewable Energy for Rural Schools’, booklet, Report BK-500-

26222, National Renewable Energy Laboratory, Golden, Co.

[24] Lilienthal, P., Flowers, L., Rossmann, C. (1995) ‘HOMER: The Hybrid Optimization Model for Electric

Renewable’, in Windpower ’95 – Procedings, American Wind Energy Association, pp. 475–480.

[25] Lundsager, P., Madsen, B. T. (1995) ‘Wind Diesel and Stand Alone Wind Power Systems’, final report,

May 1995, BTM Consult and Darup Associates ApS.

[26] Lundsager, P., Bindner, H., Clausen, N-E., Frandsen, S., Hansen, L. H., Hansen, J. C. (2001) ‘Isolated

Systems with Wind Power – Main Report’, publication R-1256(EN), June 2001, Risø National Laboratory,

Roskilde, Denmark.

[27] Lundsager, P., Bindner, H. (1994) ‘A Simple, Robust, and Reliable Wind–Diesel Concept for Remote

Power Supply’, paper presented at the World Renewable Energy Congress III, Reading, UK, 11–16

September 1994.

[28] Mortensen, N.G., Petersen, E. L., Frandsen, S. (1993) ‘Wind Atlas Analysis and Application Program

(WAsP), User’s Guide’, Risø National Laboratory, Roskilde, Denmark, http://www.wasp.dk/.

[29] Newcomb, C., Baring-Gould, I., Corbus, D., Friedly, S. (2002) ‘Analysis of Reduced Energy Capture

Mechanisms for Small Wind Systems’, in Proceedings of the 2002 AWEA Conference, June 3–5, 2002,

Portland, Oregon, USA, American Wind Energy Association.

[30] Pereira, A. de Lemos, Bindner, H., Lundsager, P., Jannerup, O. (1999) ‘Modelling Supervisory Controller

for Hybrid Systems’, paper presented at the European Wind Energy Conference, Nice, March 1999.

[31] Pereira, A. de Lemos (2000) Modular Supervisory Controller for Hybrid Power Systems, PhD thesis,

publication R-1202 (EN), June 2000, Risø National Laboratory, Roskilde, Denmark.

[32] Renewable Energy Group (1993) ‘INSEL Reference Manual’, version 4.80 ed., Department of Physics,

University of Oldenburg, Oldenburg.

[33] RETScreen (2000) ‘Pre-feasibility Analysis Software’, CANMET Energy Diversification Research

Laboratory (CEDRL), www.retscreen.gc.ca.

[34] Shirazi, M., Drouilhet, S. (2003) ‘Analysis of the Performance Benefits of Short-term Energy Storage in

Wind–Diesel Hybrid Power Systems’, Report CP-440-22108, National Renewable Energy Laboratory,

Golden, Co.

[35] Tande, J. O. G., Palsson, M. Th., Toftevaag, T., Uhlen, K. (1999) ‘Power Quality and Grid Connection of

Wind Turbines. Part 1: Stationary Voltages’.

Wind Power in Power Systems 329

//INTEGRAS/KCG/P AGIN ATION/ WILEY /WPS /FINALS_1 4-12- 04/0470855088_ 15_CHA14 .3D – 330 – [299–330/32]

20.12.2004 7:46PM