43 Cristina Ionici

Analele Universitii Constantin Brncui din Trgu Jiu, Seria Inginerie, Nr. 3/2009

Annals of the Constantin Brncui University of Trgu Jiu, Engineering Series, No. 3/2009

387

CONSIDERAII PRIVIND

AMENAJRILOR

HIDROENERGETICE CU

ACUMULARE PRIN POMPAJ

Cristina IONICI, dr.ing.Universitatea Constantin Brncui

Rezumat : n aceast lucrare sunt prezentate avantajelor sistemului de producere a energie n amenajrilor hidroenergetice cu acumulare prin pompaj. Sunt prezentate dou tipuri de circuite de transformare a energie n amenajri existente n lume, artnd diferenele din punct de vedere economic. O astfel de amanajare este n studii i la noi pe rul Tarnia- Lpuneti. Cuvinte cheie: energie, amenajare, ru 1. Sistemul energetic

Amenajrile hidroenergetice cu

acumulare prin pompaj, AHEAP, sunt destinate mbuntirii funcionrii sistemelor energetice. Sunt utilizate pentru reglajul frecven-putere din cadrul graficului de sarcin, fiind obligatorii n cazul existenei n sistem a unui productor care nu are flexibilitate pornire-oprire, central nuclear electric. Acest sistem asigur o frecven unic, alimentarea cu energie electric a tuturor consumatorilor, elimin pagubele pricinuite n producie prin ntreruperile curentului i micoreaz rezerva total n sistem.

n sistemele energetice se ine seama n mod permanent de evoluia productorilor de energie, dezvoltndu-se mereu acele compartimente care corespund n cea mai mare msur creterii consumului i dup un program de amplificare accesibil pentru economia rii.

ntr-un sistem energetic este necesar: rezerva de exploatare sau de sarcin

CONSIDERATIONS ON HYDRO-

ENERGETIC PUMPING

STORAGE ARRANGEMENTS

Cristina IONICI, dr. eng.,

UniversityConstantin Brncui Abstract: In this paper presents the advantages of the energy production with hydropower developments pumped pompaj.Two examples of pumped storage are presented in the world in comparison to our national power system for the need for these works.. Are two types of circuits for conversion of existing accommodation in the world energy, showing differences economically. Such is amanajare and new studies on the river Tarnia-Lpuneti. Keywords: energy, arrangement, river 1. Power system Hydropower accumulation by pompaj, AHEAP, are intended to improve the functioning of energy systems. Are used for frequency-setting power of the load chart and binding in case of a production system that has flexibility-Off, the nuclear power. This system provides a unique frequency, power supply for all consumers, eliminates damages occurred in production due to power interruptions and decreases total reserve in the system Power systems always consider the evolution of power producers, always developing those compartments that correspond to a great extent to consumption increase according to an amplification program accessible for the countrys economy.

A power system requires: Operation or load reserve in order to

maintain the frequency at occasional load peaks exceeding normal maximum values (approximately 5% of the maximum load in large systems and more than 5% in



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pentru meninerea frecvenei la vrfuri de sarcini ocazionale care depesc maximele normale (aproximativ 5% din maximul de sarcin n sistemele mari, i mai mult de 5% la sisteme mici);

rezerva de avarii pentru nlocuirea produciei de energie a agregatelor scoase din funciune n mod neprevzut (10-15% din maximul de sarcin);

rezerva pentru reparaii planificate. Astfel, n cadrul bilanului de energie

al sistemului, la nivelul anilor 2000-2007.

small systems); Faults reserve for replacing aggregates

power production removed from operation unpredictably (10-15% of the maximum load);

Planned repairs reserve. Therefore, in the system power

balance, in 2000-2007, percentage distribution on types of power sources was as follows:

Tabelul 1. Variaia surselor de producere a energiei n perioada 2000- 2007

2000 2007 Termocentrale pe crbune/ Coal steam power plants 39,6% 35,2%

Termocentrale pe hidrocarburi/ Hydrocarbons steam power plants 31,9% 23,8% Hidrocentrale/ Hydroelectric power plants 26,7% 31,3% Centrala nuclear Cernavod/ Nuclear power plant from Cernavoda 2,7% 8,8%

La nivelul anului 1998, investiia

nuclear nceput la Centrala nuclear Cernavod acoperea deja peste 10% din cererea naional de electricitate, n condiiile n care centrala funcioneaz, aa cum se cunoate doar cu prima unitate. La nivelul rii, la o putere electric total instalat de circa 19000 MW, consumul intern a sczut de la 9-10000 MW sub putere medie anual de la nivelul anului 1989, la 6-7000 MW n 2007, i a continuat s scad n continuare, ceea ce a dat posibilitatea selectrii obiectivelor de modernizat n electrocentrale. Costurile de producie n aceste centrale aveau urmtoarea configuraie: termocentrale pe crbuni 42,8

dolari/MWh termocentrale pe hidrocarburi 36,17 dolari /MWh hidrocentrale 4,3 dolari/MWh centrala nuclear Cernavod 28-30

dolari/MWh. 2.ncadrarea centralelor hidro electrice cu acumulare prin pompaj n sistemul energetic

In 1998, the nuclear investment

initiated at Cernavoda Nuclear Plant already covered over 10% of the national power demand, if the plant operated, as known for the first unit. At the level of the country, from a total electric power of 9-10000 MW annual average power in 1989 to 6-7000 MW in 1997 and continued to decrease which allowed to select the objectives to be modernized in power plants. Production costs in these plants had the following configuration: Coal steam power plants 42,8

dollars/MWh Hydrocarbons steam power plants 36,14

dollars/MWh Cernavoda nuclear plant 28-30

dollars/MWh 2.Hydroelectric power plants inclusion with pumping storage in the power system



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Centralele hidroelectrice cu acumulare

prin pompaj se regsesc n literatura de specialitate sub denumirea de AHEAP sau transformatoare hidroenergetice (The). Acestea primesc la primar energie electric de baz E1 kWh, (P1 - kW) i produc la secundar E2 (P2) de vrf. Transformarea energiei electrice i nmagazinarea ei n rezervoare sau lacuri, pe cale complex electric, mecanic, hidraulic, justific denumirea de The. Necesitatea construirii The provine din nevoile acoperirii consumului electric variabil n timp i anume: iarna, consumul energetic este cu 30-50%

mai mare dect vara; n zilele lucrtoare consumul depete

cu 50- 80% pe cel de duminica i srbtori legale;

n orele zilei consumul la vrful de dimineaa i seara depete pe cel de noapte (golul curbelor de sarcin, cnd exist excedent de energie) cu aproximativ 60-80%.

Variaia n timp a sarcinii electrice P=f(t) impune anumite moduri de ncadrare n sistem a diferitelor categorii de centrale electrice: centralele nuclearo-electrice funcioneaz

la baza inferioar a graficului sarcinilor cu Tu=7000-8000 h/an, unde Tu=E/Pi

centralele termoelectrice cu arderea de lignit i crbune inferior funcioneaz la baza a doua, cu Tu=5500-6500 h/an;

centralele cu arderea de gaze se ncadreaz la semibaz, Tu=5000 h/an;

centralele hidroelectrice fluviale i cele cu cderi H mici, debite Q mari i volume utile n lacuri Vu foarte reduse se ncadreaz la semibaz sau semivrf, cu Tu=3500-5500 h/an;

centralele hidroelectrice gravitaionale, cu lacuri i cderi mari, funcioneaz la vrful graficului sarcinii, cu Tu=1500-2500 h/an;

transformatoarele hidroenergetice (The) sunt utile i economice la vrfuri nalte i

Pumped storage hydroelectric plants are found in the specialty literature under the name of hydroenergetic transformers (The). They primarily receive main electric power E1 kWh (P1 kW) and secondarily produce top E2 (P2). Power transformation and its storage in tanks or lakes in a complex electric, mechanic, hydraulic way justifies the name of The. The need to build The comes from the needs to cover variable electric consumption, namely: In winter, power consumption is 30-50%

higher than in summer; During business days, consumption

exceeds that of Sunday and legal holidays by 50-80%.

During the day, morning and evening peak consumption exceeds the night one (load curves hole, when there is power excess), by approximately 60-80%

Electric load variation in time P=f(t) requires various methods for including electric plants in the system: Nuclear-electric plants operate at the

lower base of loads charts with Tu=7000-8000 h/year, where Tu=E/P

Lignite and inferior coal burning steam power plants operate at the second base, with Tu=5500-6500 h/year

Gas burning plants are included in the semi-base, Tu=5000 h/year

Fluvial hydroelectric plants and those with small falls H, large flows Q and useful volumes in small lakes Vu are included in the semi-base or the semi-top, with Tu=3500-5500 h/year

Gravitational hydroelectric plants, with big lakes and falls operate at the peak of the load chart, with Tu=1500-2500 h/year

Hydroenergetic transformers (The) are useful and economic at high short-period peaks, with Tu below 1500 h/year

Power transformations cycle is complex: electric-mechanic-hydraulic and consists of two distinct phases: Primary phase (pumping), where power is

sampled from the electric network,



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de scurt durat, cu Tu sub 1500 h/an. Ciclul transformrilor energetice este

complex electric-mecanic-hidraulic i const din dou faze distincte: faza primarului (pomparea), n care din reeaua electric se prelev puterea, prin transformatorul cobortor al tensiunii, electromotorul antreneaz pompa i debiteaz apa n rezervorul superior sau n lac; faza secundarului (turbinarea) ncepe dup un anumit timp, n care apa pompat rmne nmagazinat n rezervor, apoi este golit prin turbina care antreneaz generatorul, a crui putere se restituie reelei, din nou prin transformatorul de ridicare al tensiunii electrice.

through voltage decreasing transformer, electric engine drives the pump and discharges water in the higher tank or in the lake;

Secondary phase (wheeling) begins after a while, while water remains stored in the tank, then it is emptied through the generator driving turbine, whose power is given back to the network, again through the electric voltage increasing transformer.

Fig. 1 Grafic de funcionare a centralelor/ Plants operating chart

Durata ciclurilor, compus din cele dou faze, difer dup gradul compensrii sarcinilor, ca: ciclu zilnic, ciclu sptmnal, ciclu sezonier i foarte rar, anual. Cel mai frecvent este ciclul zilnic n care se compenseaz sarcinile de vrf cu cele ale golului de noapte. 3. Tipuri de circuite transformatoare

Construciile hidrotehnice i echipamentele electromecanice, ca i debitele Q, cderile H, puterile P, determin dou tipuri de circuite, fiecare cu dou subtipuri, i anume:

- AHEAP n circuit nchis sau deschis: - pur, V turbinare=V pompare

- mixt, Vturbinare= V pompare+ Vaf n continuare se prezint calculul

Cycles duration, consisting in the two phases, differs depending on loads compensation, as: daily cycle, weekly cycle, season cycle and rarely annual cycle. The most frequent is the daily cycle where peak loads are compensated by the night hole. 3.Types of transforming circuits

Hydrotechnic buildings and

electromechanic equipments as well as Q debits, H falls, P powers cause two types of circuits, each with two subtypes, namely:

-AHEAP, closed circuit - mixed

We next describe the economic calculation for the closed circuit.



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economic pentru circuitul nchis: 3.1. Transformatorul hidroenergetic (The) cu circuit nchis pur

Acesta const din rezervorul superior Rs, rezervorul inferior Ri, conduct, galerie sau pu forat i centrala cu echipamente electromecanice. Circuitul este caracterizat prin:

V1= V2=V, avnd volumul pompat V1 (m3/ciclu) egal cu V2 turbinat;

Hb1= Hb2= Hb , cderi brute egale Hmaxim, H minim; H1 > H2, cderi nete cu H1 = Hb+hr1 , i H2 = Hb-hr2 ; Qi1 < Qi2 , debite instalate, datorit P1 < P2 ;

E2 = E1 - energia produs, ce este mai mic dect energia consumat la pompare E1. randamentul global, unde indicii

reprezint randamente pariale:

3.1.Hydroelectric transformer (The) with closed-pure circuit

It consists of the upper tank Rs, lower tank Ri, pipe, gallery or forced shaft and electromechanic equipments plant. The circuit is characterized by:

V1=V2=V, with pumped volume V1

(m3/cycle) equal to wheeled V2; Hb1=Hb2=Hb, equal gross falls,

maximum H, minimum H H1>H2, net falls with H1=Hb+hr1, and

H2=Hb-hr2; Qi1



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n schema de funcionare se introduce volumul V (m3/ciclu), provenit din precipitaiile de pe versani ce nconjoar rezervorul sau din captarea unor aflueni, pe cale gravitaional. Se numete circuit mixt deoarece V2 = V1 + V > V1 , caz n care pierderea de energie ntr-un ciclu este:

(m3/cycle) resulted from precipitations from mountainsides surrounding the tank or by gravitationally collecting certain affluent. It is called mixed circuit, because V2=V1+ V>Vt, where the power loss in a cycle is:

+==

1121 V

V11EEEE kW/h (4)

la un randament de aproximativ 0,65, V

trebuie s fie: V = 0,54 V1. Dac coeficientul este mai mare dect 0,54 The devine supraportant i deci se ctig energie. 4. Concluzii

Dezvoltarea energeticii ca ramur duce att la creterea consumului de energie ct i la creterea puterilor la vrf. n perspectiv un rol important l vor avea centralele nuclearo-electrice, centrala Cernavod, care vor asigura energia necesar sistemului iar pentru vrfurile de sarcin trebuie construite transformatoarele hidroeneretice. S-au nceput cercetrile n acest sens pe Tarnia-Lpuneti, construcia fiind obligatorie la intrarea n funciune a grupului 2 al centralei nuclearelectrice de la Cernavod.

BIBLIOGRAFIE [1]. Dorin Pavel - Hidrotehnica vol. 17 nr. 5 / 1972 Bucureti. [2]. Creu Gheorghe, Preluschek Ervin Economia Apelor [3]. Water Power & Dam Construction february 1991 [4]. Site Apele Romne.

therefore, at an approximately 0,65 output, V has to ve: V=0.54V1. If the coefficient is greater than 0.54 The becomes over-carrying and power is gained. 2. Conclusions The further development of electrification results not only in the growth of power consumption and in the growth of peak values as well. In the future, Cernavoda nuclear-electric plant will continue to provide main power, with the operation of the 2nd unit and steam power plants will operate less and less due to limited classic fuels. For the semi-peak and peak of the load chart, gravitational hydroelectric plants will be used with big lakes and high falls, as well as fluvial plants and for the most pronounced load peaks hydroenergetic transformers have to be built, both with closed circuit and open circuit. They began this research in the Tarn-Lpuneti, construction is required in operation group 2 of the Cernavoda plant Nuclearelectrica. BIBLIOGRAPHY [1]. Dorin Pavel - Hidrotehnica vol. 17 nr. 5 / 1972 Bucureti. [2]. Creu Gheorghe, Preluschek Ervin Economia Apelor [3]. Water Power & Dam Construction february 1991 [4]. Site Apele Romne.

43 Cristina Ionici

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