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St.John's

MINI-HYDRO SYSTEMS USING

INDUCTION GENERATORS

by

°NORRIS EATON

A thesis submittedinpartial fulfillment of the requirements for the degree of

Master of Engineering

Faculty of Engineering and Applied Science Memorial University of Newfoundland

July1997

Newfoundland Canada

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Abstract

Thisstudy has focused on developing and documenting a systems approach toward modem electrical design that minimizes the cost of building and operating a grid<onnectedmini-hydroplant. The thesis applied innovative electrical design to reduce capital costs, lower operating costs, increase efficiency, and maximize revenue. Thiswas achieved by following a multi-diciplined engineering approach, selecting a standard three-phasesquirrelcage induction motor as the grid-connected induction generator, automating and remotely controlling the plant to eliminate the cost of a full-time operator, and incorporating an irmovative diagnostic expert system to quickly assistinisolating the cause of a plant shutdown.

Itwas clearly established that a significant reductioninthe capital cost of electrical equipmentisachievableifthesquirrelcage induction motorisused as the induction generator. The "off-the-shelf' induction motor and standard solid- state motor starter are relatively inexpensiveincomparison to custom induction or synchronous generators. Since standardthree-phase, 575V induction motors have ratings less than 200 kVA, the focus was on grid connected. mini-hydro developmentswithaninstalledcapacity of less than 200 kVA. Stand-alone plants,

li

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considered.

Knowing when to use an induction generator,andthe type of control philosophy to implement,isbasedon the assumption the electrical designer has an understanding of the complete mini-hydro development process, consequently the thesisalsocovered the general design of mini-hydro systems. Whilethis isnot an exhaustive treatment of the subject matter, itisan indication of the level of understanding required for the electrical design.

The thesis documents the theory, performance characteristics, and design considerations associated with an induction generator,inan effort to evaluatethe appropriateness of installing the induction generator atagrid-eonnected location.

Also, a method was presented for selecting the standard squirrel cage induction motor to use as an induction generator. Induction generator protection requirements, utility protection, and mechanical systems protection were investigated, and modem solutions proposed. The PLC wasused.to automate the plant and cost effective remote control options were explored.. An innovative and novel diagnostic expertsystemwasdeveloped and demonstrated. Finally, the systems approach and documentation of modern electrical design and operating methodswasapplied to a practical example, a150 kWinstallation proposed for Nipper'S Harbour.

ill

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Acknowledgement

F~my mostsincereappreciationto Dr.M.A.Rahman for presenting the opportunity to participateinthe Master of EngineeringProgram.. Also,without his encouragement, guidance and unlimited patience over the years, the completion of this course of study would not havebeenpossible.

Aspecial thanksto Dr.L.Lye and Dr. J.E. Quaicoe for their advice and support, to the members of the supervisor committee for their constructive criticisms,toDr.J.I.Sharpefor helping me put the thesisinitsproper perspective from timetotime, and to Moya Crocker for alwaysbeingpleasant when handling thesis logistics.

Last, butcertainly not least, itisonly the unquestioned trust, constant encouragement and sacrifice of myfamilywhichhasmade it possible for me to complete this work. To my wife Marina,thankyou. To mychildren,Allison and Andrew, when times were tough,thanksfor not mentioning the liT" word. Yes,it istrue, the thesisisfinallyfinished!

iv

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92 93 94 4.4.1 SwitchingDevice - Motor Starter (52) . . . . 94 4.4.2 Short-Circuit Protection (50) . . . 96 4.4.3 Overload Protection (51) . . . .. % 4.4.4 Ground Fault Protection(,5OC;) . . • • • . . . .. 98 4.4.5 Phase Unbalance Protection (46) . . . . 99 4.4.6 Over-Speed Protection (12) .. . . • . . . 100

4.4.7 Protection ofMechanical Systems . 100

4.5 UtilityProtection . . . 101

4.5.1 Power Factor Correction Capacitors and Self-Excitation 102

4.5.7 Main Transfonner _ . . . . 105 106 107 108 . . . 104 104 105

4.5.6 lightningArrestors . 4.5.2 Over-Voltage Relay 4.5.3 Under-Voltage Relay

4.5.4 Over/Under Frequency Relay . 4.5.5 ReclosureEffects . . . • . .

4.6 Automation of thePlant viii

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Minimum Automation . . . • . . . • . . . • ••. 110 4.6.2 Full Automation

4.7 Remote Monitoring and Control 4.8 Expert System. Diagnostics

4.8.1 Introduction .

4.8.2 Review ofExpertSystems

4.8.3 ExpertSystem Diagnostics . . . • . . . • . . 4.8.4 Expert System. Example

150 kW Induction Generator Example 5.1 Introduction.

5.2 Induction Generator Selection 5.3 Major Electrical Equipment 5.4 Protection Scheme 5.5 OperationalModes 5.6 Monitoring and Control Scheme 5.7 Special Considerations

112 115 123 123 125 128 130

132 132 133 135 139 141 141 143

6 Summaryand Conclusions 148

References 155

Appendices 164

A Application for Water Use Authorization&Preliminary Licence

~Nipper's Harbour 164

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C EnergyCalculation Spre..dsheet· Nipper's Harbour D Capital Cost Estima.te· Nipper's Harbour E Economic Evalua.tionSpreadsheet -Nipper's Harbour F Swrurwyof Project Fe..tures - Nipper's fhrbour G DebriledSte..dy State Analysis of the Induction M..chine H ExpertSystem Documentation

H.l Hydro Plant Equipment.

H2 Problems and Symptoms H3 DecisionTree

H4 Qualifiers, Variables, andOloices H5 ExpertSystem Ruies

H.6 "HYDR<nEXE"SounEGxle . . . . • • • . . • . . • • . • . . • . • . . H.7 External Interlace

HB Report Generator ..

H.9 CustomScreens .

H.lO System Configuration Options

173 183 189 191 198 202 215 216 217 220 221 228 737 2~

244 245 253

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List of Figures

2.1 Flow Duration Curve - Nipper's Harbour 34

3.1 Induction Motor EquivalentCircuittypicallyusedfor power

calculations . . . 61

3.2 Induction Motor EquivalentCircuit 62

3.3 Induction Motor EquivalentCircuit-ImpedanceDiagram 62 3.4 FallRiver670 HP Induction Machine - Stator Current,It •vs Slip 75 3.5 FallRiver670 HP Induction Machine - Output Power,POt, vs Slip 75 3.6 FallRiver670 HP Induction Machine - Torque vs Slip 76 3.7 FallRiver670 HP Induction Machine - Power Factor,pI;vs Slip. 76 3.8 FallRiver 670 HP Induction Machine - Efficiency,1],vs Slip 'T/

4.1 Remote Monitoring and Control- Option 1 . . . 119 4.2

4.3

Remote MonitoringandControl- Option 2 . . . • • • • . . ..

Remote Monitoring and Control- Option 3 _ . _ . . • . • • • . ..

.120 .121 4.4 Remote Monitoring and Control- Option 4 .

5.1 Single Line Diagram .

. . . 122 136 5.2 Remote Monitoring and Control - Nipper's Harbour . . . 145 5.2

5.3 A.1

Control Schematic - Nipper's Harbour . PLCLogiCDiagram - Nipper's Harbour . Mapof Nipper's Harbour Drainage Area

. . . • • . . . . 146 . . . • • • . . . 147 .172 H.1 ExpertSystem Decision Tree

xi

. . . • • • • • • . • • • . . . 220

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List of Tables

2.1 Ranking of SiteswithExisting Infrastructure _ _ . . . . • • • • • • _ 30 22 RankingofGreen Sites _

2.3 Hydrology Information - Nipper's Harbour 2.4 Site Parameters - Nipper's Harbour

32 . . • • • • • • • • • . . 33

. . . • . . . . 38 2.5 Preliminary CapitalCost Estimate-Nipper's Harbour 47 2.6 Newfoundland HydroPricingStructure . . . 48 3.1 FallRiverExample -Induction Motor Nameplate Data 63 3.2 Fall River Example - Induction Machine Design Constants . 64 3.3 FallRiverExample - Per Unit (p.U.)BaseValues 65 3.4 Fall River Example - Computed Values of Machine Parameters for

Steady Slate Operation 74

5.1 Specifications forthe200 HP Squirrel Cage Induction Motorusedas

a 150 kW Induction Generator . 135

5.2 Utility; Generator, and Mechanical Protection specified for the

150 kW Nipper's Harbour Mini-Hydro Plant. 140

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Table of Symbols

""

AI C CCA CEA

cr

DA DCS DDE DRD DSG E.

E1S EMAC EX5YS FSL FVNR h HP Hz [, [, I....

ID 1Ft ILl<

1m

lRR kVA kVAba5e kW kWhr LISP LSL

Efficiency

Locked.rotor power factor angle Power factor angle

Synchronous Speed, radians per second Artificiallnlelligence

Cprogramminglanguage CapitalCost Allowance Canadian Electrical Association Current Transformer Drainage Area Distributed Control System Dynamic Data Exchange (Microsoft) Drainage Density

Distribution System Generator Airgap voltage

Environmental Impact Statement Electrical Manufacturers Association of Canada Expertsystem programming shell Full Supply Level

Full Voltage Non-Reversing Head

Horsepower Frequency Stator current Reflected rotor current Base Current Inner Diameter of the Pipe Full load current LockedRotor current Magnetizing current InternalRate of Return Kilo Volt-Ampere BasekVA(3~) Kilowatt Kilowatt-hour

Symbolic programming language LowSupply Level

xiii

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MHz MMI MPU MW n, n.

NUG p P PC pi pfrL pfu>.

Pfwo PIN PINeFL PfN-g<ttl.

PrN-"""arL PLC P.

PriFL Po PoeFf.

P""",, Po.malt>.

P"

PR1.FL P"

PRlOFL

PU PV Q Q- R, R, R", RFP Rm

rpm

Frequency.. megahertz ManMachine Interface Magnetic Pickup Unit Megawatt Normal turbine speed Turbine runawayspeed

Specific speed of the turbine atfulloutput andbestefficiency Non-Utility Generator

Number of poles Power Personal Computer Power factor Full load power factor Locked Rotor power factor Friction,. windage and stray load loss Input power

Full load input power Generator mode input power Motor mode input power Programmable Logic Controller Core 12R loss

Full load core PR loss Output power Full load output power Generator mode output power Motor mode output power Stator I2R loss Full load stator PR loss Rotor FR loss Full load rotor [2R loss Per Unit Present Value Flow rate Average stream flow Stator effective resistance Reflected rotor resistance Rotor Start resistance Request for Proposals Core loss/iron loss resistance Revolutions per minute

xiv

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5 SCADA SF S.

Ss

T~n.

T_..

V

V,.

VAR V"

Vu V.

WSC X, X, Xm Z,., Z....

Z"

Zm 2/Q /,,/

Resistive Temperature Device Slip

Supervisory Control and Data Acquisition Service factor

Rotor Speed, rpm Synchronous Speed, rpm Generator mode torque Motor mode torque Voltage Base Voltage (1<1»

Base Voltage (3<1»

Reactive volt-ampere Full load voltage Line-to-line voltage Base Terminal Voltage Water Survey of Canada Stator leakage reactance Reflected rotor leakage reactance Magnetizing reactance Locked Rotor impedance Base Impedance Locked Rotor Impedance Magnetizingbranchimpedance Total impedance of the induction machine

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Chapter!

Introduction

1.1 Research Rationale

The problem of increasing demand for electricityisbestaddressedby encouragingenergyconservation and the development of alternate energy sources..Theother choiceistocontinuebuildinglargescale thermal, nuclear. and hydroelectricplants,allofwhich have major environmental, social andfinancial costs. Small-scale renewable sources of energy, such as solar, wind, waveand mini-hydro, hold promise. Actual development: of thesesmall scale energy sources depends on the level of advancement of each specific technology, and the climatic and physiographic features of the area where the technologyistobeused.Eastern Canada, especially Newfoundland and labrador, have the precipitation levels and geographic featureswhichfavour small and mini-hydroelectric developments[l].

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called on private companies (NUG's - non-utility generators) tosupplya portion of thegrid-connected electrical demand using alternateenergysources. Developers have responded withproposalsfor cogeneration facilitiesandsmall-hydro projects (greater than1MW).Verylittle attention was given to grid-connected mini-hydro developments (less than 1 MW), mainly because the economies of scale tend to favourthelarger developments.

Mini-hydroisan attractive energy source. Amini-hydro plant uses a renewable energy source whichisenvironmentally benign, thereislittle disroption of fish habitat, no impairment of navigable wate1Ways, and minimal flooding. A mini-hydro developmentcanbebrought onstreammore quickly than larger hydro projects, usually within one construction season. Since no heatisinvolved in theprocess, equipment has a long life,minimalmaintenanceisrequired, and breakdowns arerate.A physical plant lifegreaterthan fifty yearsisnormal. The hydraulic and civil engineering technologies are well-developed and proven, with recent advancesinturbine design and construction methods resultinginincreased efficiency and reduced capital costs.

Thus, an economically viable, grid-connectecl, mini-hydro projectispossible when creative civil, mechanical and electrical designs are used tominimisethe cost of building and operating the plant. Simplified. and standardised design

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be the

approach of custom designingeachhydroelectric plant

The objective of thisthesisis todevelop a systemsapproachand.

documentation of modern electrical designandoperating methods for amini- hydro plant.Thisfocuswilllessen the capital cost of the electricalsystemsand reduce operating costs, contributing to the overall economic viability of themini- hydro development. Further reductioninproject costisachieved when a multi- disciplined engineering approachis used.during the mini-hydro plant design phase. The plantwill begrid-connected, remotely controlled and automated, and willuse a standard induction motor as an induction generator. Specifically, the induction generator significantly reduces the cost of the electrical equipment package,and remote control of the plant eliminates the full-time operator cost.In addition,. anexpertsystem decreases down·time and maintenance costs. The expertsystem quicklydiagnosesthecause of a plant shutdown,. and recommends remedialaction.

Induction generators,insmallsizes,are lower in cost than synchronous generators, requireless complex: controls, and are simpler in construction.

Standardsquirrelcage induction motors canbe usedas low-voltage induction generators in the smaller grid connected mini-hydro plants (less than 200 kW).

The motors,usedas generators, are significantly cheaper than similarly sized custom induction generators or synchronous generators.

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operator. Asan example, a typical 150 kW run-of-river plant, with a capacity factor of 50%,willgenerate revenues of approximately $40,000peryear, assuming a blended rate for energy and demand of approximately 6 cents/kWhr. Obviously thisplant cannot support afull-timeoperator, andwillnotbeviable without automatic and remote control. Advancesinsmall programmable logic controller (PLC)design, and a corresponding reduction in hardware costs, make it possible to implement automatic and remote control strategies previously only available to larger hydro plants. The ptCisalso used to collect the necessary field data needed as inputs to the diagnosticexpertsystem.

1.2 Literature Review

Now, andinthe past, mini·hydro developmenthasbeen regarded as a good source of hydroelectric power for isolated communities and remote industrial sites, yet grid-eonnected mini-hydro developments were generally not considered tobecost effective. The majority of the mini-hydro plants connected today to the Newfoundland grid started as stand-alone power plants, then were connected as the transmission system expanded. into their geographic area. The exception,. the Morris hydro plant[2], located on the Avalon peninsula in Newfoundland, was conceived as a grid-eonnected. mini-hydro development. Itis part of the Newfoundland Power system. Newfoundland Power originated from

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an amalgamation of isolated hydro plants, many aninstalledcapacity less than1MW.

DuringthepeakhydrodevelopmentyearsinNewfowulJand, the 1960's and.1970's, consumer demand, economies of scale, and a lackofpublic awareness of environmenteffectsencouragedthedevelopment ofthelarger hydroelectric facilities. Grid-connected. mini-hydro developments could not compete. Today, thepublicisaware of the environmental andscxiaIcosts of large scale hydro developments, consequently thereisrenewed interestingrid-connectedmini- hydro. The most recent environmental regulations governing hydro development, specifically inthe province of Newfoundland &::Labrador[3], recognises the environmental attractiveness of mini-hydro. The regulations state that any proposed development lessthan1 MW (mini-hydro), which does not infringe on a special area,isautomatically exempt fromtheenvironmentalreviewprocess.

Even though research and developmenteffortsinthe mini-hydro field focused onmakingstand--alone plants more efficientandcost effective, the resultant improvementsinturbine design. hydrologic analysis andcivilstructures are equally applicable to grid-connected mini-hydro developments. Recent references, including textbooks and design manuals, have increased their effort to document the progression of designchangesapplicabletosmall and mini-hydro systems, regardless of whether the plantisgrid-connected. or stand-alone. Older standard textbooks, H.K Barrows[4] in1943 and W. Creager[S] in 1950,

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concentrated on thelargehydro systems. More recent texis, specifically

J.J.

Fri12[6]

in1984 and J5. Gulliver[7]in1991, dealwith smallhydro developments and the concept of a multi4isc:iplinary approachtodesignanddevelopment. However, thesmaller ofthe small-hydro projects,ormini-hydro,receive supecfluous coveragein thesetexts.

Still, miniandmi~hydrosystems werethe recipients of considerable coveragedwing the1980's,withdocumentation usuallytaking theform of design manuals.A.R.Inversin[8] published. an excellentmi~hydrosourcebookin1986, andin1987, Energy, Mines and Resources Canada commissioned a small/mini hydro handbook for Newfoundland and Labrador[9]. Other reference materials were the result of small hydro workshops, conferences and demonstration projects[10 - 171. However, none of the references view the mini-hydro systems and components fromtheelectricaldesigner's perspective, whichiscritical, since theelectricaldesignerwillbeexpectedto selectthe most appropriate generator type,protection system, and plant controlstrategy.

Recent electricalresearchconcentrated on introducing alternatives to the traditional synchronous generator, the mainstay of stand-alone mini-hydro plants.

Of course, the synchronous generatorhas the abilitytomaintaina constant voltage and frequency under varying loads. The self-excited. single-phase synchronous generator, permanent magnet synchronous generator, and self-excited induction generator havebeenproposed as possible alternatives to the conventional stand-

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electronics and controller hardware made it possible to regulate the voltage and frequency ofthesegeneratorsinstand-alone applications.

In theareaofself-exdted single-phase synchronous generators, steady-state perfonnance analysis technique were introducedbyS. Nonaka[18, 19]. A.M Osheiba and MA. Rahman[201presented a dynamic performanceanalysisofself- excited single-phase synchronous generators, using the d-qaxis simulation technique, which yields Significant improvement over the steady-state approach.

The permanent magnet synchronous generator concept as reviewed by K Binns andA.Kurda1i[21],continuestoreceiveSignificantresearcheffort,with modelling tecluUques recently presented by Rahman and Osheiba[22].

Unfortunately, thethreealternatives mentioned incorporate relatively complex control methods to solve the problem of controllingthesystemvoltageand.

frequency. Such complexityandcostisunacceptableina grid<onnectedmini- hydro application, especially when an induction generator, connecteddirectlyto thegrid,requiresno additionalcircuitrytomaintainacceptable voltage, frequency and phase relationships.

Research inthearea of self-excited induction generators for stand·alone applicationshas resulted. in a better understanding of abnormal operating characteristics, conditions that are also a concern for grid<onnected induction generators. Thefirstanalysisof self-exdted induction generator characteristics

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induction machine, driven mechanically, may become se1f-excitedifcapacitors are connectedacross its terminals. Itwasfortyyears later before practical control of self-exc:itedinduction generators was possible, using static exciters. In1979, M Brennen and A Abbondanti[24] propo<ed,andtested, a static exciter usingfixed capacitors and thyristor controUed inductors. Since then a variety of staticpower control designs, analysis techniques,andtesting methods havebeenpublished in the literature[25 - 34]. Variations on the standard static<ontrolled. induction generator theme have also been presented., asinthe case of R. Bonert and G.

Hoops[35], who proposed an electronic impedance controller to control the voltage and frequency of a stand-alone induction generator. Thestand-alone induction generatorresearch hasindirectl.y made a contribution to grid<onnected induction generator applications, specificallywithrespecttounderstanding over- voltage conditions caused by generator averspeed.

The concept of using an induction machine as an induction generatoris certainly not a new idea. It wasoriginally investigated byH.M.Hobart andE.

Knowlton [36] in1912. Their review assumed a grid<ennected induction generator, as opposed to a stand-alone system,. since stand-alone operation was not teclutically feasible at that time. Still, there were few grid<onnected induction generator installations until the 1940's. In1948 farmers and small industries in northern Californiabegan installing engine driven induction generators to

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'Thisspurred Smith[37J,in1950, to develop a method of calculatingthegenerator rating of an induction motor, standard motors thatwerebeingusedas generators by the farmers. Four yearslater,in1954,J.E. Barkleand RW. Ferguson [38] presented a paperdiscussing the theoryof operation of the grid-connected induction generator, the self-excitation problem,andother application problems that should beconsidered when designing an induction generator installation Unfortunately, thereare no further references to induction generatorsinthe literature until 1980, other than those previously mentioned which specifically refer to se1f-excitation and stand-alone induction generators. Thus, during the 1960's and 1970's the induction generator was ignoredbymanufacturers, researchers and industry.

Anenergyshortage intheearly 1970's, due to the Middle East oil cartel, was the cause of renewed interest in the grid-connected induction generator.1bis time,theinduction generator was being considered for waste-heat recovery and cogeneration schemes. Between 1980 and 1983, RL Nallen [39 - 41] wrote a series of articles highlighting the virtues of the induction generator for thistypeof application The petroleum and chemical industries installed induction generators. E.L. Owen [42], in 1983, documentedhisexperiences with a 13,000 HP induction motor/generator installation, while in 1984,

J.R.

Parsons [43] published a paper comparing an induction generator to a similarly sized synchronous machine in atypicalcogeneration scheme. However, there are no references in the

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literature which document similar detailed experiencesinthesmallor minihydro field.L Pererira[44] and L Schafer[45],in1981 and 1982 respectively, did publish articlesinWater Power and Dam Constructionwhichdealtwiththegeneral conceptof induction generators ingrid<onnectedsmall-hydro applications.

Unfortunately, they did notpresent a comprehensive document which would take theinformedreader from thetheoretical analysisof inductionmachines,through toa practical design and implementationofan induction generatorinamini-hydro installation. Aswell, practical operational and installation considerations,with respect to using standard induction motors as induction generators, have notbeen concisely presentedinthe literature.

Asrecognized by R.L Nailen[40], the grid-connected induction machine requires similar protection when operated as a motor or generator. Two excellent articles, one writtenbyH.A.Breedlove[461in1983, and the otherbyJ.D.

Bailey[47Jin1988, review,ingeneral tenns, both thegenerator and utility protection requirements of agrid<onnected induction generator. Recent developmentsinmicroprocessor controlled. motor starters have made it possible to further improve the protection schemes for mini·hydro induction generators.

However, the application of the new protection methodstogrid<onnected induction generators has notbeendocumented.

A mini-hydro plant may not afford a full-time operator, thus implementing automatic monitoring and controlisa key elementinmaking any mini-hydro

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development economically viable. With the proliferation of small, inexpensiveand powerful programmable logic controllers (PLCs), itisnow feasible to automate even the smallest plant. However, actual experienceswithPLCbasedcontrol of mini-hydro plants have not been documentedintheliterature. References found on automatic control generally referto hydro systems inexeess oftoMW.In1989 J.P. Cross[48] described the STS Hydropower(USA) experiencewithimplementing a remote monitoring scheme which, unfortunately,ismuch to costly to be considered for mini-hydro applications. Alsoin1989, S. Isakson[49] reviewed computerbased control systems for hydro power control, but again, the literature focusedon thelargerhydro installations, siteswiththe resources to purchase custom control hardware and software. Standard protection and control strategies for very small hydro generators, ofalltypes, are docwnentedina 1984 CEA Report[SO}. Obviously, the report does not incorporate the significant technological improvements of the last 10 years. Available today are motor starters capable of providing sophisticated generator protection,. and inexpensive PLCs with the ability to be continuously monitored from a remote location.

Remote and automatic control of a grid-connected mini-hydro plant, using Pes and PLCs, introduces an opportunity to use mcpert system diagnostics to quickly identify the source of problems that may cause the plant to shut down.

Expert system technology, as a component of the artificial intelligence field, came to the forefront in the mid 1980's, with subsequent publication of numerous articles

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and texts.Ljohnson[51L and D.A. Waterman[52], in 1985 and 1986 respectively, authored.separate texts describingthedevelopment ofexpertsystems and potential applications inbusiness, medicine andindustry. The software implementations of initial diagnostic expertsystemapplications were writtenin FORTRAN,C,or Turbo Prolog. As interestdeveloped,expertsystemshells appeared on the market, including EX5YS Professional[53]. Theliterature search found diagnosticexpertsystem. papers dealingwith thepower distribution field[54,55],butfewdealingwithhydroelectric plants[56, 57], and no references to diagnostic expert systemsbeingused to improve operationsinsmall ormini- hydroplants.

1.3 Scope of Work

Thestated objectiveistodevelop a systems approachanddocumentation of modem electrical design and operating methods for a grid-connected, remotely controlledandautomatedmini-hydroplant,. one which uses a standard three- phase induction motor as an induction generator. Since standard "off-the--shelf' three-phase, 575V induction motors have ratings less than 200 kVA, thefocusison mini-hydro developments with aninstalledcapacity of less than 200 kVA. Stand- alone plants, similar to those foundinisolated communities and mining sites, are not considered. The electrical design and operating methods presented assume the plantisgrid-<:onnected.

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The electrical system should incorporateallmini-hydro components which affectandinteractwiththe grid system, includingtheprime mover, induction generator, controlsystem,interconnection requirements, and protection scheme.

As well, knowing when to use an induction generator, the appropriate prime

mover to select, and the type of control philosophy to implement,isbased on the assumptiontheelectrical designerhasan understanding of the completemini- hydro development process. Regulatoryissues, environmental regulations, site selection, hydrology, powerandenergy estimates, physical components, and economic evaluationwillimpact on the electrical design and operating methods of the mini-hydro plant. Consequently, Chapter 2 covers thegeneraldesign ofmini- hydro systems. Whilethissectionisnot an exhaustive treatment of the subject matter, itisan indication of the level of understandingrequiredfor the electrical design.

The induction generatorisan obvious choice for a small grid-connected mini-hydro installation. Itisrugged, inexpensive, and simple to protect and control. Chapter 3 introduces the induction generator concept, aswellas selection, protection and control of the standard squirrel cage induction motor used as an induction generator. Thisinduction generating partisnot covered adequatelyin the standard textbook. Also includedisa technical analysis of the induction generator, and performance prediction of the induction motor when run as a generator. Modern electrical design methods are applied and documented to

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produce reliable, cost effective generator and utility protection. The sum of the information presentedisChapter3issufficient to evaluatetheappropriateness of installingan induction generator at a grid-eonnected location.

Automatic operation of a grid-connected mini-hydro plantwilleliminate the annual cost of a full-time operator. Thus, Chapter 4 documents the design process of automating the plant, using cost effective PLCs, Pes, motor starters, power monitoring equipment, man-machine interface(MMI)software, and expert system shells. Modem methods and systems for the protection, control and automatic operation of a mini-hydro plant are researched, selected, and documented. Unfortunately, the lack. of a full-time operator means an on-site expertisnot availabletodiagnose the cause(s) of a plant shutdown, when it occurs.

Thus, a diagnostic expert systemispresentedinChapter 4, one which constantly monitors the operation of the plant. The expert system assists maintenance personnelindetecting the cause of a plant shut-down, thus minimizing downtime.

Decisions are made based on the status of plant sensors when the shutdown occurred,and maintenance personnel intervention is activated. by modern telecommunications.

Chapter 5 applies the systems approach and documentation of modern electrical design and operating methods. Threepotential grid-connectedmini- hydro sites on the island of Newfoundland are comparedinChapter 2 and one, Nipper's Harbour,selected. for development The detailed. electrical design is

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completed for the Nipper's Harbour site, usingthesystemsapproach documented.

inChapter 3 and Otapter 4. First,theappropriate t:hree-phase induction motor, whichwilloperate as a generator,isspecified. Then, operational procedures are identifiedand.protection and control systems designed.

The summary, conclusions, innovative aspects of the research, and suggestions for future work are presentedinChapter 6.

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Chapter 2 Design of Grid Connected Mini-Hydro Systems

Chapter 2 covers the general design of mini-hydro systems. Knowing when touse an induction generator, and thetype of control philosophy to implement,is based.on the assumption the electricaldesignerhasa good understanding ofall aspects of a mini-hydro development. Urisincludes the regulatory process, environmental issues, site selection, site hydrology, power and energy estimate, rates, and economic evaluation. Whilethissectionisnot an exhaustive treatment of the subject matter, itisan indication of the level of understanding required of the electrical engineer.

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21 The Regulatory Process in Newfoundland

2.1.1 Non-Utility Generators (NUG's)

Any successful grid-connected hydro development must have a buyer for the energy produced, and satisfactorily addressall local, provincial, andfederal regulatory issues. Recent Newfoundland and Labrador legislation (1989) [58]

permitsprivate development ofsmallandminihydro resources, typically sites withaninstalledcapacity of less than 15 MW. 1brough the legislation the private developers, called Non-Utility Generators (NUG's), have access to the water rights of streams located on the island of Newfoundland. Before the legislation, Newfoundland and Labrador Hydro Corporation (N£1d. Hydro) held the exclusive rightstoallhydro developments on the island, regardless of size. Nfld. Hydrowill now waive theirrights to thesmallandminihydro sites. The provincial Department of Environment andLandsregulates the development processby issuingPreliminaryWater Use Authorizationtoqualifying parties.

2.1.2 The Market

Currently, the only buyer for power produced by NUG'sisNfld. Hydro, who issues request for proposals(RFP)when expected. consumer demand exceeds system capacity. The successful bids are awarded a longterm25 year power contract,withan option to renew for an additional25years. Only oneRFP,for50 MW of installed capacity,has beenissuedto date [59].

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21.3 Water Rights

Any NUG interestedindeveloping a mini-hydro siteinNewfoundlandhas to adhere to a specific regulatory process. The developer must first identify the holder of thewater rights of the stream of interest. Onthe island of Newfoundland, water rights are held by Nfld. Hydro, Newfoundland Power,Deer Lake Power Co., and Abitibi-Price Inc.. Developers interestedinwater rights held byNewfoundland Power, Deer Lake Power, or Abitibi-Price. must negotiate directlywiththose companies. WaterRightsheld by N£ld. Hydro are controlled bygovernment legislation, Section 21 oftheDepartment of Environment and l=dsAct, 1989[58].

The legislation states that NOd. Hydro must waive its rights to the development of the hydro potential of any stream,witha capacity of 15 MW or less,ifNfld. Hydrohasno immediate plans to develop that stream. The first NUG to apply to have the water rights waivedwill beaccepted.In themeantime, the NUG must also apply to the Deparbnent of Environment andLands,Water Resources Division, Water Rights Section, and request to have the waived water rights to the stream transferredtothe NUG.This typeof request to the Water Resources Divisioniscalled an Application for Water Use Authorization. An exampleisgiveninAppendix A.

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The specific legislative authority, procedures, and guidelines for Water Use Authorization are giveninthe govemment publication "Guidelines Regarding Application

for

WaterUseAuthorization (Water Use Ucence)farAHydroelectric Project"

[60]. Thepurposeof the water use licenceisto enable the applicant to secure the waterresources at the proposedsitenecessary for the operation of the project,. and togenerate hydroelectric energy for a specific period of time. No other rights to water use are conferred. Asswningequivalent quality of two competing applications for development at the same site, the first proposal submittedwill have precedence.

Apreliminary licenceisissuedfor a one year period, giving the proponent authorization to undertake relevant surveys and field investigationsinthe area, prepare the feasibility study, and undertake environmental impact studies. An application for Water Use Licence mustbefiled. before expiration of the preliminary licence. The issuance of a Water Use Licencewilldepend on the quality of the proposed project,intermsof multiple and optimum utilization of the available water resource, minimal environmental disruption, and land use conflicts. Asmentioned, Appendix A includes the Nipper's Harbour mini-hydro Application for Water Use Authorization, and preliminary licence, as an example.

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22 Environmental Issues

Electricityisanintegralpartof our society, powering ourlights, washers, stoves, and computers. [fwe are not willing tototallyforsake these necessities and conveniences, then we must accept thefact thattherewillalwaysbesome environmental damage causedbypower generation equipment Tominimizethat damage we should first reduce our demand for electricity, then select small-scale, renewable power sources which have the least effect on the environment.

A mini-hydro plant, being asmalldevelopment,isone of the most environmentally sound methods of producingelectricity.Itisinconspicuous, uses a renewable resource, andhasa negligible impact on the environment. Existing ponds areusedfor storage, nolandisflooded, the dams are small concreteand timbercrib structures, anditdoes not disturb the fish habitat. Scheduled salmon rivers are avoided.

While mini-hydroisrecognized asbeingenvironmentally friendly, the proposed developments still must adheretoallregulations and follow the correct regulatory process. Thus, concurrentwithobtaining a waiver from Nfld.Hydro, and applying for Preliminary Water Use Authorization, the proposed project must becleared from the requirements of theEnvironmental Assessment Act, 1980[3]. The Regulations of the Act listallundertakingswhichmustberegistered. All proposed developments, large or small, which involves land use, forests, water or

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n

animallifemustbebrought to the attention of the Minister of the EnvironmentU itisdetermined the project, including mini-hydro developments,willhave a significant impact on the environment, the undertakingwillhave to be registered.

Ifthe undertakingisnot listedinSchedule 1 of the Act,~UndertakingsSubjectto Registration"[3], the projectwill not have toberegistered.

Mini-hydro developmentsOessthan1MW)are not considered to be an undertaking subject to registrationifthe following conditions are met; the plant capacityisless than 1 MW, the area to be floodedisless than 500 hectares, no floodingwilloccurinaspecialarea, no developmentislocatedwithina special area., and no transmission line or roadisto be located at a distance greaterthan500 metres from an existingright-of~way."SpecialAreas" are listedinSchedule 2 of the Regulations[3] and include scheduled salmon rivers, waste disposal sites, wildlife reserve areas, provincial parks, protected water supply areas, and others.

Any mini-hydro undertaking required to register may have to prepare a complete Environmental Impact Statement(EIS)[3}. The cost of an EIS would make most mini-hydro developments uneconomical.

Once the undertakinghasbeencleared from the requirements of the Environmental Assessment Act, 1980, [3} other provincial and municipal authorities are freetograntapprovals asrequired. The federal Department of Fisheries and Oceans mustbecontacted whenever fish habitatisaffectedbythe undertaking. The proponent must submit annApplication for Authorization for

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Works or Undertakings Affecting Fish Habitat"[61] before proceedingwithany work at the site. Stringent regulations apply when the stream of interestisa scheduled salmon river, thus development on these rivers should be avoided. Due to lack of economies of scale for a mini-hydro plant,. the cost of meetingall environmental requirements at such a site are prohibitive.

2.3 Site Selection

The site selection process for amini-hydrodevelopment begins with noting the geographic region where developmentispermitted,listing the desirable characteristics of the ideal location. undertaking a map survey to identify favourable sites, then following up witha site visit. Siteswithexisting infrastructure, typically reservoirs, dams, and pipelines, are scrutinized first. Any site characteristicwhich reduces capital costs, usually easy access, small dams, and short penstocks,willmake the proposed development more appealing.

Desirable physical characteristics of a grid-<:onnected mini-hydro site include medium to high head, sufficient stream flow, close to a suitable transmission line, proximity to passable roads, short penstock length, natural head pond, upstream storage, access to telephone lines or cellular telephone, and located near a gauged stream. Other factors to consider include land ownership, and other users of the stream. Water Rights and environmental concerns mustbeconsidered concurrentlywiththe initial map survey and site visit:. Thereisno pointin

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pursuingtheundertaking at a particular siteifwater rights are not available or obvious environmental issues preclude development.

2.3.1 Map Survey

The map survey shows the obvious, such as the distance of the site from the nearest road, transmission line length, penstock length..grosshead, and drainage area. The data fromthe1:50,000 topographic map surveyissufficient to give an indication of the energy generation capacity of the site, approximate capital cost, and to complete a preliminary feasibility study.

A value for gross head(h)and stream flow (Q)isneeded to calculate the power(p)production capability ofthesite.

P:9.81xphxQ (2.1)

Thegrossheadisthe differenceinelevation between the normal water level at the intake and the water level at the turbine outflow. It does not take into account the losses occurring throughout a hydro generation system. With practice, the gross head estimate taken from the 1:50,000 mapiswithin10% of the surveyed gross head. The accuracy improves as the gross head increases(8]. The stream flow (Q) usuallyisnot available from direct measurement.Itmustbederivedbyprorating the drainage area and MeanAnnualRainfall (MAR), using a nearby gauged stream as the reference. The 1:50,000 mapisusedto findthedrainagearea.

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Themap survey provides preliminary estimates ofpenstock.length and distancefromexistingroads and transmission lines. Thelength of thepenstock shouldbeas short as possible. Asite may have sufficient flowandadequate head, but theriseinelevationisvery gradual,requiringa longpenstock. A long penstockisexpensive anditisthemaincause formaking asiteeconomically unattractive. Also,heavy equipment must have accesstothe site duringthe construction phase. Roads to the powerhouse, intake structure, and along the penstock route are necessary. Obviously, the closer the siteisto any passable road, the less road the developerhasto build. Since powerhastobedelivered to the utilitygrid,the site mustalso beclosetoathreephasedistribution line. Thehigh voltage transmission lineis of no use here, as they require an expensive transformer andswitchyard to make the connection to the low voltage generators (600V) typicalinmini-hydro.Distribution lines are not necessarily shown on the topographic maps, but they nonnally parallel secondary roads that lead tosmall communities. Anysite closetoa communitywillmostlikelyhave access to a distribution line. AcheckwithN£ld. Hydro, or Nfld. Power,willconfirm the type and size of the distribution line in the area of interest.

For maximum energy production, the development requires a method of capturing and storing the excesswaterflowing during thehighrun-offperiods.

During the map survey, look for locations on ponds upstream oftheintake where

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low lying timber crib dams couldbebuilt.Consider that thedamshould block off a naturalbasinand shouldbeeasilyaccessible via road or cat-track.

2.3.2 Site Visit

Assuming the water rights are available, the 1:50,000 topographic map survey resultswillindicate whether a site visitiswarranted. The site visitwill identify factors normally not available from the map survey, which might affect the viability of a development. Those factors include the possibility of the stream beingusedas a municipal water supply, the presence or absence of migratory fish, access to the construction site, the location of the intake dam, land ownership, and potential downstream effects.

Many of the promising streams are located close to communities,mainly because thatisthe mostlikelyplace of finding a three-phase power distribution line. Unfortunately, the stream of interest maybethe community water supply.

According toMinisterialpoticy[60}, applications for Water Use Licence shall have precedenceinthe following order; domestic purposes, municipal purposes, commercial and industrial pwposes, hydroelectric generation purposes, recreational purposes, and other prescribed purposes. U the streamisused as a municipal water supply, the townhasexclusive rights to the complete watershed of that stream. Nothing further canbedone until the permission of the townis secured. The provincial department responsible for Environment cannot overrule

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the municipality. Yet, ahydroplant canbebuilt on the same stream as a municipal watersupply. Iftheplantisdownstream of thewatersupply intakeitwillnot degradethewatersupply_Ifitisupstream of the intake, special precautions have to betaken toensure that the watersupplyis not contaminated during construction or operation ofthemini-hydrodevelopment

A hydropower project cannot interferewithmigratoryfish.beitsalmon..

arctic char, or troutIfthe streamofinterestflows intothesea,checkthe area to seeifafallsblocks the path of themigratoryfish. Next,checkwiththe local people to seeifthey are aware of the type offishthat use the stream.Finally,contact the Federal Department of Fisheries and Oceanstoseeifitisa scheduled river, oris protected.inany way.

While the map surveywillgive an idea of the proximity of the site to a passable road. a site visitwillconfirmthetypeofterrain,the existence of new roads not shown on the map, and theexistenceof any old roads ortracksthat couldeasilybeupgraded. Ifthe terrain does notpermitthebuildingof a road to the intake or powerhouse, consider the additional cost of bringing the equipment inbya winter road, boat, or helicopter. Also, since a short penstockisthe most desirable option, check theterraintoensurethatthepenstockcanbebuilt over the cliffs and steep sections. Perhaps a slightly longer but more accessible route would becheaper to build. As for thedam.select a location thatisina natural basin with a narrow outlet and steep walls.'Thiskeepsthedam short and small, minimizing

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the cost A solidrockfoundationisanother important consideration when selecting adamsite.

While the watershed area ofthedevelopmentisusuallycrown land,the power-houseisoften located close to a community, and maybeon privately owned land. Acquiring private landisdifficult, not because of cost, but because of the problems tracing ownership and obtaining clear title. One method of avoiding private landistohave the penstock. route parallel the stream-bed. Earlyland grantsleft a narrow strip of land along the banks of the stream.. Recent grants have a wider buffer zone, 15 metres, along each bank. Check the provincial Crown Landsand Registry of Deeds to see how much landisavailable along the banks of the streaminquestion.. and whether penstocks can be built onthisland. Also, beware ofbuildinga hydro plant upstream of a coaununity or farm. Ifflooding does occur, the owner of the plant maybeblamed for the flooding, evenifthe hydro plant was not responsible for such flooding.

23.3 SitewithExisting Infrastructure

Asan illustration of the site selection process, the author focused on the island of Newfoundland, where legislation (1989) [58] now permits private development of hydroelectric sites less than 15 MW. Only mini-hydro sites, 1 MW or less, areconsidered..

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Aspertheselection processes outlined previously,initialinvestigations focusedon identifyingsiteswithexistinginfrastructure.. Threeinteresting sites surfaced.specifically;the Marble Mountainskiarea mow-making water-line, whichiscapable of developing 120 kW of outputpowerwhennot beingusedto makesnow; the now defunct ERCO (Long Harbour) phosphoruswatersupply system. includingclam.. reservoir, andpenstock.whichcouldbeconvertedtoa 500 kW mini-hydroplant; andfinally,the excess capacity of the Comer Brook Pulp&:

Paper Ltd.millwater supply (Glynmilllnn Pond), capable of generating 250 kW.

Whileall of these sites are economically attractive, none havebeen developed because of water rights issues, uncertainty about infrastructure ownership, and conflicts between multiple users. 'TheMarble Mountain site developmenthasnot progressed because the waterrightsare heldbyDeerLake Power, and thereisconcern aoout theeffectthe plantwillhave on theSteady Brook municipalwatersupply. Boththe watersupply and hydro plant would drawwaterfrom the same stream.The ERCOwater supply site holds promise, andiscurrentlybeinginvestigated by a number of companies. While thewater rights to the EReO site appear to have been settled, ownership of the infrastructureisstill an issue, consequently no developmenthas takenplace. The GlynmillInnPond site would have tobe a joint effort between Deer Lake Power andtheinterested party, since the water rights are heldbyDeerLake Power and

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the damisownedbyCorner BrookPulp &:PaperCompany Ltd.. No known activityor developmentisplannedfor this site.

TIlefavourable sitesselectedmustberanked to determinethepreferred development. A spreadsheetwasusedto implement a ranking system. and to ascertain whichsite{s)has the best chanceofbeingdeveloped. The sites were rated onallissues, including technical, environmental, regulatory and operational. The resultsof the rating process for sites with existing infrastructure are shownin Table 2.1.

The ERCO water supplyisobviously the most attractive site,mainly because of the existing dam and penstock, and excellent long term storage. The spread between the

ERea

site and the remainder of the sitesisnot as great as one would expect. The uncertainty associatedwiththe ERCO -Land/Facilities Ownership· and -Other Users/Interests- categories kept its overall rating down.

While the

ERea

site shouldbepursued, the developer mustbeaware of the risk of notgainingaccess to the infrastructure.

Inreferencetothe information giveninTable 2.1 and Table 2.2,. the -RANK- column assigns a weight(0-5)to each category. The higher number reflects the relative importance of each category,withrespect toallother categories. Aswell, each categoryisrated according to it's effect on each individual project. The NRATING" can range from

a

^to10. Ratings greater than 5 areusedto account for existing infrastructure or unusual circumstances.Asan

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example, an undeveloped site requiring a very shortpenstockwould receive a rating of 5, while a sitewithan existingpenstockmight receive a rating of 9.

Table 21: Ranking of SiteswithExisting Infrastructure

EKCO MAIlBL£ GLYNMILLI:NN

WATER SUPPLY MOUNTAIN POND

500kW 120kW 2SOkW

pTAGORY RANI( RATING TOTAL RATINGTOTAL RATING TOTAL

(O-S) (0-10) (0-10) (0-10)

PENSTOCK LENGTH S 7 3S to 50 3 IS

DAM LENGTH

, ·

³⁶

·

³⁶ ^to

^"

~ANSMISSIONACCESS TO INTAKEUN£ LENGTH 33 to3 30

. ·

to

^"

30 10

^,

¹⁸30

....CCESS TO POWERHOUSE 3 to 30 10 30

.

⁷¹

ACCESS TO PENSTOCK ROUTE 3

· ^"

^to ³⁰ ¹⁰ ³⁰

WINTER ACCESS 3

,

18 8

"

⁸

"

WATER, RIGHTS S 7 3S 2 10 2 10

ENVIRONMEl'ITAL APPROVAL S

· ^"

⁷ ^3S ³ ^IS

MIGRATORY FISH

,

8 32 10

"

³ ¹²

STORAGE

,

10

"

² ⁸

,

"

FLOW VARIABILITY 2 10 2Il

·

¹⁸ ³

^,

WINTER OPERAnON 2 7

"

⁸

"

⁷

"

INT'ERCONNECTlON COSTS

,

3 12 8 32 S 2Il

REMOTE CONTROL COSTS 3

,

12 S IS 7 21

LAND/FAClUTIESOWNERSHlP 5 2 to 2 10 2 to

ISIBILITY 2 8 16 3

. ^,

⁸

0TI-fERtJSERS/tNTERESTS

,

2 8 2 8 2 8

TOTAL POINTS 429 i l l 332

PRIORrrY 1 2 3

2.3.4 Green Site

While the sites with existing infrastructure are very attractive, the complications caused by water rights and ownership issues usually mean the siteis

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not available for developmentbyprivate individuals or companies. Thus the site selection focus must shift to sites where the water rights are ownedbythe provincial government and available tobetransferredto private developers.

Usually these sites are called green sites, sites where no civil structures are currently in place. Based on the map survey criteria outlined, three of the most favourable grid-eonnected mini-hydro sites on the island of NewfoWldland were selected. They include Western BrookandEasternBrook near Uttle Coney Arm, and Nipper's Harbour. All have good access via road, medium tohighhead, short penstocklength, and are close to a distribution line. None were located on scheduled salmon rivers, or near municipal water supplies. The results of the ranking process for the green sites are giveninTable 22.

Nipper's Harbouristhe bestgreen site alternative available, where water rights and access are not an issue. The site has a number of attractive physical features, including no other users of the water supply, no salmon or sea trout migration, short penstock length, natural head-pond, extremely small dam required, existing road access to powerhouse and lower penstock, short transmission line (0.7 km), direct connection to the N£ld. Hydro system, access to telephone line, and proven energy potential and drainage basin characteristics.

The major disadvantages of the site are the difficult access to the upper penstock route and minimal long-term storage. The Nipper's Harbour sitewillcontinue to

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be usedas an example throughout Chapter2.Asummaryof the project features of the Nipper's Harbour siteis listed inAppendix F.

Table22; Rankingof Green Sites

NIPPal~ WESTDN

...

KARIlOUR BROOK BROOK

6SOkW 600kW SOOkW

pTAGORY RANK RATING TOTAL RATING TOTAL RATING TOTAL

(O-S) (1)-10) (0-10) (1)-10)

PENSfOCK LENGrH

, · ^'" ^,

¹⁵

· ^'"

DAMlENGTII

· ·

^{I '}

^,

¹² ²

^•

TRANSMlSSION LINE LENGTH

,

2

• ·

¹²

^,

¹⁵

ACCESS TO INTAKE

,

2

• ·

²⁶ ² ⁶

ACCESS TO POWERHOUSE

,

7 21

·

¹²

^,

^{I '}

ACCESS TO PENSI"OCK ROtJ'TE

,

2

• ^, ^,

²

·

WINTER ACCISS

,

·

¹² ¹

^, ^• ^,

WATERRIGHrS

,

10 50

,

2S

,

2S

ENVIRONMENTAL APPROVAL

, ,

2S

,

2S

,

2S

~~~RYFlSH

· · ^, ^, ^'"

¹²

^, ^,

¹²

· ·

¹ ^{I '}

·

FlOW VARlABII.JlY 2

,

6

,

6

, ·

WINTER OPERATION 2

· ^•

²

^· ^, ^·

lNTERCONNECTlON COSTS

· ·

^{I '} ^I

^·

^I

·

REMOTE CONTROLCOSTS

, ,

15 I

,

t

,

1.AND/FAaunES OWNERSHIP

, · ^'" · ^'" ^,

¹⁵

"""'UTY

²

,

10

· · · ^•

OTHER USERSjlNlnESlS

· ·

^{I '}

^,

¹² ²

·

rorAL POINTS 285

21.

189

PRIORITY 1 2 3

2.4 Site Hydrology

The site hydrology informationis usedtoselecttheinstalledcapacity of the turbine and generator, and to predict the average annual energy production of the

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plant 1hen the energy estimate,inconjunctionwitha capital and operating cost estimate derived£rom theinstalled capacity,isusedtoperform an economic evaluationof theproposed project Completing theinitial hydrology workin- house.usingavailable manpowerandapplication software, significantly reduces project costs. Italsogivesthedeveloper more control over thetypeof prime mover, generator, and controlsystemtoselect to ensure maximumenergy production. The authorhasresearched methods of performing a simplified and cost effective hydrologic analysis of a mini-hydro site. Public domain literature, historical stream flow data. and software are used throughout. The processis documentedinAppendix B, usingtheNipper's Harbour site as a working example.Asummary ofthehydrology dataisgiveninTable23.

Table 2.3: Hydrology Infonnation - Nipper's Harbour

Nipper's Harbour Hydrology Information Summary Drainage Area

AnnualMean Flow Mean Annual Run-off 100-Year Design Flood 10-Year Diversion Flood Est 2-Year 7-0ay Low Flow Est.lO-Year 7-0ayLowFlow Forebay Pondage

33.8km²

o.m

ml/s 7W ami

25 rolls 19rolls 0.066 rolls 0.005ml/s 38,700 ro^l

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24.1 Flow Duration Curve

I I I I

~1I1IIJUuuJwu.uu,u ...u._..._••• J

Figure 21: Flow Duration Curve - Nipper's Harbour

Energycalculationsrequireknowledge of the mean flow of the stream and the shape of the flow duration curve. The curve indicatestheexpectedfrequency ofallflow rates,high.average and low included, at the siteselectedfor mini-hydro development Ofcourse, a constant flow rate atalltimesisnot the nann, unless significant storageisavailable. thus flow rates vary and depend on the season, weather patterns, physiographic features and site characteristics. The hydrological

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analysis isused to calculatetheannual mean flow, derive the flow duration curve, and estimate flood flowand low flow.

The historical flow records published by Environment Canada are essential tocalculating themean flow and flow duration curve for a particular site. The Water Survey of Canada Streamflow Toolkit [68] software was used togenerate theflow duration curvedata table for Nipper's Harbour. The curve was defined.

using100 points, one for eachpercentage of flow exceedence. The flow duration curve data filewasexported. to a spreadsheet, tobeused laterinan analysis of the power and energy available at the site.

2.4.2Flow Synthesis

II the mini-hydro siteison a gauged stream the hydrological analysisis straightforward. However.ifitislocated on an unguaged stream.. the critical step iscreating synthesized flow records. Synthesized flow records for an unguaged stream are createdusingeither of the two methods recommendedina series of studies completedin1988byAcres International for the Inland Waters Directorate, Environment Canada [62, 63J. TIle methods are proration on Drainage Areaand Mean Annual Run.-of{ (MAR), and Regional Non-dimensional Flow Duration Cwves. The Nipper's Harbour example, described.inAppendix 5, generates the synthesized time series ofdailyflowsbyprorating on drainage area and mean annualrun-off(MAR). Boththe gauged and ungauged siteisassumedtohave

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similar physiographic features and site characteristics.Ifthis istrue, and both sites are relatively dosetoeachother,thenbothhave a similarMAR.1heMAR of the gaugedstream..giveninmillimetres(nun).iscaLculateddirectlyfromtheannual mean flow(m'/s)anddrninagearea(km'). Drainageareaisdeterminedby planimettyfromthe1050.000scale maps. The hydrologyn!SUltsdescribedin Appendix Bindicate the MAR for the Nipper'S Harbour mini-hydro siteis725mm and the drainage areais33.8km2.The closest gauged streamisSouth West Brook.

Station No. 02.YMOO3 of the Water Survey of Canada, andis90 miles away.

2.4.3 Flood Flow Estimate

Estimates of flood flows mustbedetermined to assistinthe safe design of the dam and to reduce the risk of damage caused.byflooding. The design flood and diversion flood.returnperiods areselectedbased on the perceived risk. The Nipper'S Harbour siteisclassified as lowrisk,. sincethereisno risk ofdamageto downstream property or loss of Life, the timber-crib dam canbesafelyovertopped..

and reconstruction costs would not be excessive. Thus,therecommended design flood returnperiodis100years,andthe recommended diversionfloodreturn periodis10years. The designfloodand diversionfloodfor Nippers Harbour were estimated using the procedures and software outlined.inthe report~Regional

Flood F..quency Arudysis

for

the Island of Newftrnndland"[64]. The report recommends using regional flood frequencyanalysisat ungauged sites and single

UMI Dc

UMI

MINI-HYDRO SYSTEMS USING

INDUCTION GENERATORS

•••

~i~=as:rviceS

a

Canada

Abstract

Acknowledgement

Contents

List of Figures

List of Tables

Table of Symbols

""

cr

V,.

Chapter!

Introduction

1.1 Research Rationale

1.2 Literature Review

J.J.

J.R.

1.3 Scope of Work

Chapter 2

Design of Grid Connected Mini-Hydro Systems

21 The Regulatory Process in Newfoundland

for

22 Environmental Issues

n

2.3 Site Selection

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