CELOVITA OBNOVA MALE HIDROELEKTRARNE (PRIMER …

© Acta hydrotechnica 18/29 (2000), LjubljanaISSN 1581-0267

69

UDK: 621.311.212.004.69 UDC: 621.311.212.004.69Strokovni prispevek Professional paper

CELOVITA OBNOVA MALE HIDROELEKTRARNE(PRIMER RUDNIŠKE ELEKTRARNE MEŽICA)

INTEGRAL REFURBISHMENT OF MINI HYDRO POWER PLANTS(CASE STUDY OF A MINE HPP)

Miha PIŠLJAR, Jože TROHA, Darko BENIGAR

Glavni cilj obnove hidroelektrarne po 30 ali več letih obratovanja je, da se oprema elektrarneobnovi tako, da bo zagotavljeno nemoteno obratovanje elektrarne naslednjih 30 ali več let.Istočasno pa je obnova priložnost, da se povečata moč in proizvodnja energije, zmanjšajo stroškidelovanja elektrarne z vgradnjo sistema daljinskega vodenja. V članku je opisan primer celoviteobnove hidroelektrarne v nekdanjem rudniku Mežica. Po petinpetdesetih letih neprekinjenegaobratovanja je bila obnovljena elektrarna z dvema agregatoma. Prva enota je bila v celotizamenjana, medtem ko je bil na drugi razvit nov turbinski rotor, druga strojna oprema pa je bilaobnovljena. Vgrajena sta bila popolnoma nova turbinska regulatorja in dodan nov sistemavtomatike posamezne enote. Obnova malih hidroelektrarn je včasih celovitejši in zahtevnejšiprojekt kot obnova večjih. Izhodiščne točke so enake: boljši izkoristek, večja moč, popolnaavtomatizacija, daljinsko vodenje, minmalno vzdrževanje. Lepi cilji, ampak težko dosegljivi zomejenimi sredstvi namenjenimi obnovi elektrarne.Ključne besede: obnova, orodje CFD, sistem upravljanja, regulator

The purpose of the integral refurbishment of old power plants is to bring the power plants into acondition that will enable them to work for the next 30 or 40 years without needing newexpenditure. At the same time, a refurbished power plant has to produce more energy, operateautomatically and require less maintenance work. A case study of such an integral refurbishment ofthe ex-mine power plant is presented in the article. A two-unit power plant was refurbished after 55years of uninterrupted operation. The first unit was totally exchanged with a new one. On thesecond machine, a new runner was developed and other mechanical equipment was renovated.Also, on both units, new governors were built, and a full automatic system was created.Key words: Refurbishment, CFD tool, Control system, governor

1. UVOD

Glavni namen celovite obnove elektrarn jepodaljšati življenjsko dobo elektrarn za 30 do40 let. Obnova male hidroelektrarne jepodobna obnovi velike hidroelektrarne, vendarz bistveno manj denarja. Polega tega so malehidroelektrarne spremenile svojo vlogo velektroenergetskem sistemu. V času izgradnjeso bile projektirane za vzdrževanje lastnegaelektričnega omrežja, danes pa so pretočne inmorajo optimalno “predelati” razpoložljivovodno energijo

Obnova običajno ni le obnova alizamenjava obstoječe opreme, ampak tudipreprojektiranje agregata. Vsaka obnova semora začeti s kratko študijo o izplačljivostiobnove in preprojektiranja elektrarne. Pri temje treba:

1. INTRODUCTION

The purpose of the integral refurbishmentof old power plants is to bring them intocondition to work for the next 30 or 40 yearswithout any greater later investment. herefurbishment of small hydro units is generallysimilar to the refurbishment of larger ones, butcan be accomplished with a relatively smallerbudget. Small units also change their role inthe electrical system. When they were firstassembled, some 40 or more years ago, theywere relatively large units and very often theyhad to maintain an island net.

Refurbishment today does not mean onlythe renovation of existing electro-mechanicaland hydraulic equipment, but also theredesigning of units. Every refurbishment hasto begin with a short feasibility study in whichthe next points have to be executed:

Pišljar, M., Troha, J., Benigar, D.: Celovita obnova male hidroelektrarne (primer rudniške elektrarne Mežica) -Integral Refurbishment of Mini Hydro Power Plants (Case Study of a Mine HPP)

© Acta hydrotechnica 18/29 (2000), 69-81, Ljubljana

70

− ugotoviti podrobno stanje obstoječeopreme.

− raziskati vodne razmere− poiskati in prebrskati obstoječo

dokumentacijo!− izmeriti karakteristike stare turbine!− ugotoviti, pod kakšnimi pogoji je varno

obratovanje elektrarne brez posadke?− kam z obstoječo posadko?− ugotoviti posebnosti posamezne elektrarne,

ki vplivajo na obratovanje, proizvodnjo,..

Če študija da pozitivne odgovore nanavedena vprašanja, potem sledi izdelavaprojekta, ki mora zagotoviti:− boljšo izrabo potencialne vodne energije− varno in zanesljivo delovanje agregatov in

elektrarne− visok in sodoben nivo tehničnih rešitev− za okolje prijazne rešitve− avtomatsko delovanje agregatov in druge

opreme v elektrarni nadzorovano prekosistema daljinskega nadzora.

Danes obnova ne pomeni samo vnovičneizdelave delov, ki so poškodovani aliobrabljeni, temveč je treba upoštevati novaspoznanja in tehnične rešitve s področjahidravličnih strojev in hidroelektrarn. Takooprema ne bo samo obnovljena, ampak sedvigne na višjo tehnično raven. Obstoječivodni potencial je bolje izkoriščen na podlagivišjega izkoristka obnovljene opreme inpovečanega pretoka. Rezultat je večja močagregata kot celote in večja proizvodnjaenergije

Povečan pretok in večja izhodna močagregata zahtevata poglobljeno študijo drugihdelov opreme s stališča hidravličnih,mehanskih in električnih možnosti,stabilnosti,… Sprememba glavnih parametrovagregata ne sme imeti nobenega vpliva navarno in stabilno delo celotnega sistemaagregata in elektrarne.

2. TEHNIČNI PROBLEMIOBNOVE

Obnova izpostavlja množico specifičnih

problemov. Na agregatu se največkratpojavijo problemi z možnimi rešitvami,predstavljenimi v preglednici 1.

− Α detailed examination of the existingequipment condition.

− Ascertain the water power conditions.− Perform a survey of available

documentation!− Measurement of old turbine and generator

characteristics!− Determine how safe the operation of the

power plant will be in the future without astaff?

− Decide how to solve the problem ofemployees after the refurbishment?

− Solve many other case-to-case specificproblems.

If the feasibility study gives the properanswers, the refurbishment of power plantequipment enables:− Better exploitation of water energy

potential− Safe and reliable operation of each unit and

of the entire power plant− Α higher level of particular technical

solutions− Safer technical solutions for the

environment− Units and power plant automation and

remote control operation.

Following the rule of technical updating,new components should not only include theremaking of the old ones, but also feature up-to-date technical achievements in the field ofwater units design and manufacturing. In thisway, the equipment will not be onlyrefurbished, but its technical level will also beupgraded. This leads to better exploitation ofthe existing catchment. Better exploitation isbased on better efficiency and increaseddischarge, which results in higher turbine andunit power output, higher energy productionand a shift of production to the field of peakdemand.

Increased discharge and unit output requiresan intensive investigation of all unit elementsin the sense of hydraulic, mechanical andelectrical ability and stability. A change of oneparameter must not have undesirable resultslimiting the ability and stability of the wholeunit and system.

2. TECHNICAL PROBLEMS OFREFURBISHMENT

The refurbishment of units presents many

specific problems. Within the unit, the nextproblems appear, and possible solutions aregiven in Table 1.



71

Preglednica 1. Pregled delov agregata in dela na njih.

Del agregata Stara oprema ObnovaGonilnik Stari gonilnik je obrabljen,

poškodovan zaradi kavitacije,erozije, pojavljajo se razpoke.

Novi gonilnik ima novo hidravlično obliko.Izpolniti mora vse zahteve po višjemizkoristku in povečanem pretoku.Da se zniža cena, se uporabi poenostavljenaizdelava varjene izvedbe gonilnika.

Turbinska gred Utrujen material, razpoke Nova gred omogoča povečano moč agregataNosilni ležaj Običajno je obrabljen Obnova (bele kovina) ali včasih zamenjavaVodilne lopatice Stare lopatice puščajo (v

zaprtem položaju) in nedovoljujejo povečanega odprtja.

Skrajšane vodilne lopatice (po popravilu)rešijo oba problema.

Gonilnikovlabirint

Relativno velike volumetričneizgube

Zmanjšanje izgub

Drsne puše Stalno mazanje in onesnaževanjevode.

Samomazalne puše – ni več potrebnegavzdrževanja in ni onesnaževanja okolja.

Tesnilka Usnjene tesnilke puščajo Nova tesnilka ne puščaRegulacijski

obročDvojni obroč togo povezan zregulatorjem. Omejenoodpiranje

Podaljšan obroč, povezan z novimservomotorjem, delujočim na visokem tlakuolja.

Regulator Običajno dotrajan s težavami privzdrževanju (ni več rezervnihdelov, slaba natančnostregulacije, nizek tlak olja.

Hidravlična naprava z zračnimakumulatorjem, standardnimi hidravličnimielementi, visok obratovalni tlak, procesorskiturbinski regulator vgrajen v opremoavtomatike agregata.

Predturbinskiventil

Pušča, ročno upravljanje Nova tesnila, obnovljen z mehanizmom zaavtomatsko odpiranje/zapiranje.

Generator Izolacije razreda B, izstrošeniležaji

Nova izolacije razreda F omogočapovečanje moči. Obnova ležajev enako kotpri turbinskih ležajih.

Vzbujalnisistem

Dinamični vzbujalnik z ročnoregulacijo napetosti

Novo statično vzbujanje z avtomatskimprimarnim napetostnim regulatorjem..

Mehanskemeritve

Nekaj membranskihmanometrov in termometrov

Novi elektronski pretvorniki za merjenjenivojev, tlakov, temperatur

Električnemeritve

Klasični instrumenti Pretvorniki električnih veličin z instrumentiin signali, pripeljanimi na sistem vodenjaagregata.

Mehanskezaščite

Ni posebnih zaščit Sistem zaščit agregata, ki obsega:− varnostni hitrostnik− merjenje temperatur na ležajih, navitju

generatorja− kontrolo tlakov v oljetlačnem sistemu.

Sistem vodenja Ni sistema vodenja. Ročnoobratovanje

Novi PLC sistem, ki zagotavlja avtomatskizagon in zaustavljanje agregata, turbinskoregulacijo, sekundarno regualcijo faktorjamoči, električne in mehanske meritve,signalizacijo in daljinski nadzor.



72

Table 1. List of the turbine unit parts and measures.

Unit part Old RefurbishRunner Old runner is worn out and

suffers from fatigue crack.New runner has new hydraulic shape. It hasto fulfil new requirements due to efficiencyneeds and greater flow.To lower costs, a simplified construction bywelding the blades between the hub and therim is applied.

Turbine shaft Fatigue problems and damagedshaft.

New turbine shaft also allows greater poweroutput and meets other requirements.

Radial axialturbine bearing

Is usually worn out. Repair, or maybe replacement.

Guide vanes Old guide vanes leak and do notafford an increase in theopening.

Shorter guide vanes (by repair) solve bothproblems.

Runner bandlabyrinth

Relatively large volumetricloses.

Reduces volumetric loses.

Sliding bushes Periodically greasing and greasein water (pollution).

Self-lubricated bushes – no maintenance andno environmental problems.

Shaft seals Leather seals had great leakage. New rubber seals - no leakage.Regulating ring Double arm, connected to

governor. Limiting opening.Extended regulating ring with new actuator,prepared for higher oil pressure.

Governor Usually worn out; difficult tomaintain (no spare parts),inaccurate, low pressure.

High pressure with standard hydraulicelements, hydro pack with air accumulator,digital governor integrated into mainSTART/STOP automation.

Turbine valve Leakage, manual drive. New seals, automated with new hydraulicactuator.

Generator Class B insulation, exhaustedbearings.

New class F insulation, which also allowsgreater output power. Bearing repairn asturbine bearing.

Excitationsystem

Dynamic exciter with manualvoltage control.

New static excitation system with automaticprimary voltage control system. Secondarycontrol from Unit control system.

Mechanicalmeasurement

Some piston manometers. New pressure, level and temperaturetransducers.

Electricalmeasurement

Classical instruments. Transducers for electric values.

Mechanicalprotection

No special protection systems. New overspeed device, level, pressure andtemperature protection in bearing, hydraulicpack and generator stator wire.

Control system No control system. Manualoperation.

New PLC control system, which includesStart/Stop sequence automation, turbinegovernor, secondary reactive power control,electrical and mechanical measurement andannunciation.



73

Vsaka obnova opreme je povezana zmnogimi problemi in vprašanji, posebno vpovezavi z omejitvami stroškov, časa, prostoragradbenimi deli. Optimizacija med vsemiomejitvami, željami, možnostmi je edennajpomebnejših korakov v procesu obnovehidroelektrarne.

3. OBNOVA STROJNE OPREME

Strojna oprema agregata zajemapredturbinski ventil, turbino s špiralo, sesalnocevjo, vodilnikom in gonilnikom ter turbinskiregulator. V članku je predstavljen postopekizračuna novega gonilnika, numerična analizatoka in zamenjava regulatorja.

3.1 NOVI GONILNIK

Geometrijske danosti stare opreme vključnos hidravličnimi oblikami (špirala spredvodilnikom, vodilnik, premer, spodnjiturbinski pokrov in sesalna cev) so omejitvepri hidravličnem projektiranju novegagonilnika. Splošna priporočila so:− Poveča se vstopni premer. Na ta način se

zmanjša vstopni kot.− Podaljša se dolžina venca, tako se posredno

podaljša lopatica. Zmanjša se okavitacijskaobčutljivost.

− Manjši vstopni kot in daljše lopaticeobičajno dajejo boljše lastnosti.

− Po pravilu ostaneta višina vodilnika invstopni premer sesalne cevinespremenjena.

Oblikovanje površine lopatice je izvedenoz navidezno tridimenzijsko inverzno metodo(Q3D). Lopatice so oblikovane s konstantnodebelino na prveh dveh tretjinah površine, nazadnji tretjini pa se tanjšajo. Stari in predlog zanovi gonilnik sta se analizirala z uporaboorodij numerične analize (CFD). Na podlagianalize toka skozi vodilne lopatice in gonilnik,je bil optimiran vstopni kot lopatic gonilnika.

Any refurbishment of the equipment isconnected with many problems and questions,particularly due to the limitations of cost, time,space, and civil works. Optimising among allthe limitations is the most important step in theprocess of refurbishment of the power plant.

3. MECHANICAL EQUIPMENTREFURBISHMENT

The mechanical equipment of the hydro

unit consists of a valve, a turbine with a spiralcase, a draft tube, and a wicket gate andrunner. In the paper, we present the procedurein more detail, with new runner calculations, anumerical flow analysis and a change of thegovernor.

3.1 REDESIGN OF RUNNER

The geometrical constraint of the oldhydraulic shape (a spiral case with stay vanes,guide vanes, a pitch diameter and controlmechanism, a bottom turbine cover and a drafttube inlet) limits the possibilities of the freehydraulic design of the spare runner. Ingeneral, the following is recommended:− Increase the inlet diameter. It reduces the

inlet angles according to an up-to-datepraxis.

− Extend the length of the rim, andconsequently, the length of blade. It reducesthe cavitational susceptibility.

− Smaller inlet angles and longer bladesusually give better results.

− As a rule, the guide vane height and drafttube inlet diameter remain unchanged.

The design of the blade surface is obtained

by using a quasi three dimensional (Q3D)inverse method. The blade is profiled withconstant thickness over the first two thirds, andthinning is profiled in the last third. The oldrunner and the proposals for the up-gradedrunner are analysed using the CFD tool. Onthe basis of flow analyses through the guidevanes and runner, inlet angles of the blade areadjusted. Other modifications are feasible aswell, but all of them have to be verified byusing a CFD tool.



74

3.2 NUMERIČNA ANALIZA TOKA

Priporočljiva je analiza vseh turbinskihdelov: špirale s predvodilnikom, vodilnika,gonilnika in sesalne cevi pri različnih pretokih-odprtjih vodilnih lopatic. V opisanem primeruje bil uporabljen program TASC FLOW.

Glavni namen analize je bil predvidetipretočne razmere in izgube v vsakem delutubine in zagotoviti mejne vrednosti zanadaljnje izračune.

Natočne razmere na vodilnik so določene zaobliko špirale. Nova oblika vodilnih lopatic pazagotavlja boljše pogoje za natok na gonilnik.

Novo oblikovani gonilnik se primerja sstarim. Najprej se analizira stari gonilnik prirazličnih odprtjih vodilnika. Nato pa določinovi in analizira pri istih odprtjih, tako da seprimerjajo primerljivi rezultati.

Rezultat pretočnih preračunov so prostorskerazporeditve hitrosti, tlakov in vektorji hitrostivzolž lopatice.

Da se dobi optimalna oblika lopatice se zarazlične modifikacije gonilnika ponovi analiza,dokler se ne dosežejo željeni parametri(izkoristek in kavitacija).

Sesalna cev se običajno ne spreminja.

3.3 REGULATOR

V starih agregatih so mehanskicentrifugalni regulatorji, ki jih je nemogočevključiti v avtomatsko obratovanje agregata,poleg tega jih je vedno teže vzdrževati in nezagotavljajo kakovostnega obratovanja.Modernizacija starih regulatorjev je mogočana dva načina:1. Samo z obnovo obstoječega centrifugalnega

regulatorja, ki se obnovi, opremi zelektromotorji in električnimi merilnimipretvorniki ter s senzorji. Servomotorostane isti. Regulator še vedno regulirahitrost, vendar je mogoče z njim upravljatipreko nadzornega sistema upravljanjaagregata. Običajno v takem primeruregulator regulira frekvenco do uspešnesinhronizacije, zatem pa prevzameregulacijo moči ali nivoja sistemupravljanja agregata.

3.2 NUMERICAL FLOW ANALYSIS

Analysing all turbine parts isrecommended: the spiral case with stay vanes,different openings of guide vanes, the runnerand draft tube. In the Turboinstitut, acomputer code TASC flow is used.

The main purpose of the flow analysis is topredict the flow properties and losses in eachpart of the turbine and to obtain boundaryconditions for further calculations.

The shape of the spiral case dictates theinlet angle to the distributor. A new guide vaneprofile has to provide the improved runnerinlet conditions.

The newly designed runners are comparedwith the old ones. First, a flow through the oldrunner is analysed for several operating pointspertaining to the appropriate guide vaneopenings.

The result of the flow calculation is a fully3D-velocity vector field, and streamlining andpressure distribution along the blade,predicting the runner cavitational behaviour.

To obtain a better runner design, theproposed new runner blade is modified wherenecessary and numerically analysed for thesame operating points. The procedure isrepeated more times until a runner with therequired performances (efficiency andcavitation) is obtained.

Usually the draft tube remains unchanged.

3.3 GOVERNOR

Existing governors on old hydro powerplants are generally still centrifugalmechanical governors without the possibilityof being included in the remote control systemand they have numerous accuracy andmaintenance problems. Modernisation of theold governors is possible in two ways:1. Refurbishing only the existing centrifugal

governor and furnishing it withelectrometers and sensors. The actuatorremains the same. The governor stillcontrols the unit speed, but it is possible tomanipulate it with the remote controlsystem. Usually the governor controlsspeed only during the synchronisationperiod. After synchronisation, the remotecontrol system controls the unit power orwater intake level.



75

2. Zamenjava regulatorja in servomotorja znovo oljetlačno napravo, zračnimakumulatorjem in novim visokotlačnimservomotorjem. Nova oljetlačna naprava jeskupna tudi za krmiljenje druge opremeagregata - predturbinski ventil, zavoro.Digitalni turbinski regulator je lahkosamostojna enota, pri manjših agregatih paje elektronska oprema skupna s sistemomvodenja agregata. Novi regulator morazadostiti naslednjim zahtevam:− Zanesljivost - vsi elementi morajo biti

zanesljivi. Zanesljivost se poveča zzmanjševanjem vgrajenih elementov(integrirani sistem vodenja).

− Uporaba standardnih industrijskihelementov hidravlike, merilnihpretvornikov, PLC. Na ta način seznižajo stroški vzdrževanja, ki mora bitihitro in preprosto.

− Uporaba visokih tlakov- danes seobratovalni tlaki hidravličnih napravgibljejo od 60 do100 barov. Z višanjemobratovalnega tlaka se manjšajodimenzije ventilov, povezovalnih cevi indruge opreme.

− Za vse uporabnike v okviru agregata enasama oljetlačna naprava- vodilnik,predturbinska loputa, obtočni ventil,zavora,..

− Nizka poraba energje - zračniakumulator se polni le občasno, ko padetlak v sistemu.

− Vzdrževanja je malo in je preprosto. Zdigitalnim regulatorjem in elektronskimipretvorniki se zgradi sistem, ki nezahteva posebnih nastavitev.

− Inteligentni komunikacijski vmesniki, kizagotavljajo komunikacijo z nadzornimsistemom. Ni več potrebnih posebnihkoncentratorjev signalov.

− Možnost ročnega upravljanja s turbino.− Vgrajene mehanske zaščite- visoka

temperatura, nizek tlak. previsoka hitrost

2. Changing of the governor and actuator witha new hydraulic pack, an air accumulatorand a new high-pressure servomotor. An oilhydraulic pack and a digital governorcontrol the other governor equipment. Insmaller units, a digital governor can be apart of the software in the Unit PLC. Thenew governor has to fulfil followingrequirements:− High reliability - all elements have to

have high reliability. Reliability alsoincreases if the number of elementsdecreases (integrated unit controlsystem).

− Use of standard hydraulic, sensor andcontrol elements. The term “standard”means market wide spread elements. Inthis case, maintenance is simple andcheap.

− High-pressure hydraulics - todayutilised oil pressure is normally 60 bars,but for smaller units, can be also 100bars. When the pressure is higher, alldimensions of pipes and actuators arereduced.

− Same hydraulic pack for all actuators ofthe unit – by-pass valve, main turbinevalve, brake, and wickets gate.

− Low power consumption-airaccumulator needs only intermittentpump work and has lower energyconsumption.

− Simple maintenance and simpleadjusting procedure. Standard elementsallow simple and infrequentmaintenance. With a digital governorand new transmitters it is also possible tobuild a governor with no adjustment.

− Direct connection with remote controlsystem and supervising system. A stand-alone governor has to have a standardintelligent interface with all data, and beprepared to transmit and to receivecommands from the Unit control system.

− Possibility of manual operation with theunit.

− Integrated mechanical protections -level, pressure temperature, etc.



76

4. OBNOVA SISTEMAUPRAVLJANJA

Upravljanje s starimi elektrarnami je

zaslužilo svoje ime - res se je rokovalo – vsese je upravljalo ročno. Meritve, signalizacijasta bila izvedena s klasičnimi instrumenti in zžarnicami. Sinhronizacija je izključno ročna.Stalna prisotnost posadke je bila obvezna.

Novi sistemi upravljanja pa mora imetivgrajene nasledne funkcije:− popolni avtomatski zagon/zaustavljanje

agregata− vgrajen mora biti merilni sistem za merjenje

mehanskih in električnih veličin.− sistem signalizacije− komunikacija na nadzorni sistem− avtomatska sinhronizacija (z možnostjo

ročne).

Sodobni PLC sistemi z ustreznoprogramsko opremo omogočajo realizacijovseh zgoraj naštetih zahtev v okviru enegasamega integriranega sistema upravljanja. Zamanjše enote je lahko vgrajen tudi turbinskiregulator v isto strojno opremo. Takšen sistemje:− zanesljiv− preprost za uporabo in vzdrževanje− cenovno ugoden− zagotavljati mora delovanje brez posadke.

Pri projektiranju obnove elektro-strojneopreme, je pomebno, da se predvidijo vsapotrebna dela za pripravo agregata zaavtomatizacijo:− vgrajeni morajo biti vsi senzorji in merilni

pretvorniki− predvideni morajo biti vsi izvršni elementi

(motorji, ventili,…).

V integrirani sistem PLC vsak signal vstopasamo enkrat. Informacija se potem uporabi vveč namenov - enkrat za zagon/zaustavitev, zaturbinsko regulacijo, signalizacijo, daljinskisistem vodenja,...

Električne zaščite generatorja so ločene indelujejo neposredno na generatorsko stikalo.Nekatere mehanske zaščite so izvedene prekoPLC (na primer temperatura ležajev,generatorskega navitja,)...

Izhodni signali- ukazi delujejo neposrednona elektromehanske člene.

Ročno upravljane je omogočeno v dvehrežimih - testnem, kjer se deluje neposredno naizvršne člene, in ročnem, kjer se upravljapreko PLC sistema posredno.

4. CONTROL EQUIPMENTRENOVATION

Old small (and also larger) hydro units have

only manual or perhaps a sort of semi-automatic control system. Other functionssuch as measurement and annunciation wererealised with stand-alone instruments, panellamps. Synchronisation is, in most cases, onlymanual. A permanent staff is required.

A new control system has to realise the nextfunctions:− start/stop unit completely automated− electrical and mechanical measurement

system− annunciation system− communication interface to remote

supervision system− automatic synchronisation

Recent PLC systems, with proper software,carry out all upper functions in only a singlehardware system-integrated control system.For small units, the turbine governor can alsobe incorporated in the same hardware. Such asystem is:− highly reliable− simple to use and maintain− simple to adjust− price/performance optimal− allows a no-staff power plant operation

When designing the unit refurbishment, it isimportant to provide all the necessary work toprepare the unit for full automation:− All sensors and transducers have to be built

in.− Control elements, such as motors and

solenoid valves have to be prepared.

Due to the integrated system, each input(digital or analogue) enters into the PLC onlyonce. Information is later used for all thenecessary purposes - start/stop automation, thegovernor, annunciation, supervision, etc.Electrical generator protections are separatedand act directly on the generator circuitbreaker. Some mechanical protections, such asthe bearing and winding temperature arerealised with the PLC system.

Output commands act upon the properelectromechanical actuators.

Manual control is also possible in test andnormal manual mode.



77

5. ELEKTRARNE V OPUŠČENEMRUDNIKU SVINCA MEŽICA

Leta 1940 je lastnik rudnika svinca vMežici začel izkoriščati vodni potencial rekeMeže. Med vojno, leta 1941, je bila vgrajenaprva enota - dvojna Francis turbina ingenerator, ki sta bila izdelana pri Ganzu vBudimpešti. Drugi agregat - Francis turbina jebila izdelana pri Voithu, medtem ko jegenerator Brown Boveri začel obratovati leta1948 (slika 1, preglednica 2).

5. HYDRO POWER PLANTS OFTHE LEAD MINE MEŽICA

In 1940 an owner of the Mežica mine »TheCentral European Mines Ltd« beganprojecting for the exploitation of the Mežastream. During the war in 1941, the first unit –a twin Francis turbine and generator - weremanufactured by Ganz, Budapest, and installed(PE1/1). The second unit - a Francis turbinemade by Voith St. Poelten in 1942 and agenerator Brown Boveri - were installed afterthe war in 1948 (Figure1, Table 2).

Preglednica 2. Parametri stare in nove turbine.Table 2. Parameters of old and new turbines.

PE1/1 Prej / Old Potem / NewPadec / Head 65 m 65 mPretok / Flow 1.3 m3/s 1.5 m3/sHitrost / Speed 750 rpm 750 rpmMoč / Power 1100 kW 1450 kWLeto izdelave / Year of erection 1943 1998

PE1/2 Prej / Old Potem /NewPadec / Head 65 m 65 mPretok / Flow 0.7 m3/s 0.8 m3/sHitrost / Speed 750 rpm 750 rpmMoč / Power 700 kW 800 kWLeto izdelave / Year of erection 1948 1998

Slika 1. Enota PE2/1 (izdelava Voith/Brown Boveri) pred obnovo.Figure 1. Unit PE2/1 (produced by Voith/Brown Boveri) before refurbishment.



78

Oba turbinska regulatorja sta bila izdelanapri VOITH St. Poelten. Zaradi nezanesljivostidelovanja, oteženega vzdrževanja inpredvidene popolne avtomatizacije elektrarneje bila potrebna celotna zamenjavaregulatorjev.

Na obeh agregatih sta bila turbinskaregulatorja zamenjana. Slika 2 prikazujehidravlično shemo obeh regulatorjev. Zaradibližine obeh turbin je bila izbrana ena samaoljetlačna naprava, s skupnim zračnimakumulatorjem, vendar z ločenim nizomkrmilnih ventilov. Za krmiljenje vodilnika jebil izbran proporcionalni ventil. Elektronskidel regulatorja je bil vgrajen v PLC sistemupravljanja. PLC sistem z ustreznoprogramsko opremo zagotavlja, avtomatskodelovanje agregata, turbinsko regulacijo,merjenje, regulacijo nivoja, moči in pretoka terkomunikacijo z nadzornim sistemom. Vsipodatki in zahtevani parametri so dostopni nazaslonu, vgrajenem na prednjih vratihupravljalne omare.

Na generatorju ni bilo potrebnih posebnihdel. Sam generator je bil obnovljen nekaj letpred obnovo. Stari ročni sistem vzbujanja jezamenjal novi statični vzbujalni sistem zelektronskim regulatorjem napetosti.

Obnova prvega agregata je bila uspešna, Nasliki 3 sta prikazani krivulji izkoristka in močistare in nove turbine. Fotografija na sliki 4 paprikazuje novi agregat.

VOITH St. Poelten made all threemechanical governors. In spite of permanentmaintenance, the turbine equipment neededextensive refurbishment. The owner’s goal - tointroduce remote control - has dictatedconsiderable modernisation.

New governors were created on both units.Figure 2 shows the hydraulic scheme of boththe hydraulic parts of the governors. There isonly one oil reservoir and one air accumulatorwith two separate sets of control valves. Aproportional valve is used for wicket gatecontrol. The electronic digital part of thegovernor was realised as a part of an integratedPLC control system. The PLC, with propersoftware, executes all start/stop automationfunctions, level and power control, speedcontrol, and measurement of all electricalparameters. All information is presented on anMMI monitor on the front cubicle doors.

There were no special works on thegenerator, except excitation. There was a newstatic excitation system.

Refurbishment of first unit was verysuccessful. Figure 3 shows the old and the newefficiency and power results. On Figure 4, theupgrading unit is shown.

Slika 2. Hidravlična shema regulatorja.Figure 2. Hydraulic scheme of governor.



79

0

10

20

30

40

50

60

70

80

90

100

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8Discharge Q (m3/s)

Effic

ienc

y η ηηη

(%)

0

100

200

300

400

500

600

700

800

900

Turb

ine

pow

er P

t (kW

)

η - new

η - old

Pt - new

Pt - old

Slika 3. Karakteristike stare in nove turbine.Figure 3. Old and new runner characteristics.

Slika 4. Povečani agregat PE1/1.Figure 4. Upgraded and refurbished unit PE2/1.



80

Slika 5. Novi agregat PE1/1 moči 1.45 MW.Figure 5. New unit PE1/1 of 1.45 MW.

Stari agregat PE1/1 je imel večje poškodbena ležajih in gredi. Turbinska oprema je biladotrajana, generator pa ni dovoljevalpovečanja moči. Stari agregat je bil v celotizamenjan z novo horizontalno Francis turbino,s sinhronim generatorjem z drsnimi ležaji,predturbinsko loputo z avtomatskimupravljanjem in z varnostno utežjo zazapiranja. Turbina nima lastnih ležajev, pač paje rotor turbine prevesno nameščen na

Unit PE1/1 suffered serious injuries on itsbearings and shafts. The turbine equipmentwas worn out and the generator did not allowfor upgrading. The old Unit was substitutedwith a modern single Francis unit with ahorizontal axis spiral a Frances turbine, asynchronous generator with slide bearings, abutterfly valve with an 0,8 m diameter, and abifurcation of 1,4/0,8 m diameter, a flywheeland an over-speed device. The turbine does nothave its own bearings. The runner is directly



81

podaljšano gred generatorja. Turbinskiregulator je v celoti nov. Sistem upravljanja jeenak sistemu upravljanja obnovljenegaagregata PE1/2. Na sliki 5 je prikazan noviagregat.

mounted on the generator shaft. The governoris completely new. The control system is thesame as in the refurbished unit PE2/1. It is alsoa voltage control system. Figure 5 shows thenew unit.

5. ZAKLJUČKI

Obnova in povečanje moči malihhidroelektrarn je zahteven poseg, tako kot privelikih elektrarnah. Obnova malehidroelektrarne je lahko temeljitejša kotobnova velikih enot. Dosežki pri povečanjuizkoristka so opazni in uporaba CFD orodijdaje uporabne rezultate. Izkušnje in rezultatimodelnih raziskav in preizkusov ter CFDorodje skupaj dajeta dobro in zanesljivonapoved povečanja izkoristka.

Turbinski regulatorji, sistemi vodenja,napetostni regulatorji predstavljajo opremo, kimora biti zamenjana. Sodobni sistemi sozanesljivejši, potrebujejo manj vzdrževanja inomogočajo daljinski nadzor.

5. CONCLUSIONS

The upgrading and refurbishment of a smallhydro plant is as considerable as that of largerones. The refurbishment of a small hydro plantcan be more radical than a large one. Theachievement in efficiency and power isnotable. Experiences with CFD tools aregood. Together with experience and supportfrom the existing model, experiments givereliable and good results.

Equipment such as the governor, controlsystem, and voltage control must be changed.Recent technology and development enable anew, effective, reliable approach in the field ofcontrol and hydraulics. New systems have tobe more reliable, simple to operate, able to bemaintained infrequently and supervisedremotely.

Naslov avtorjev - Authors' Address

mag. Miha PIŠLJARJože TROHA

Darko BENIGARTurboinštitut

Rovšnikova 7, SI - 1120 Ljubljana

Documents

CELOVITA OBNOVA MALE HIDROELEKTRARNE (PRIMER …