US1671046A - Hydroelectric installation - Google Patents

Description

May 22, 1928.

A. PFAU HYDRO ELECTRIC INSTALLATION Filed Sept. 6. 1921 2 Sheets-Sheet l May 22, 1928. 1,671,046

A. PFAU HYDRO ELECTRIC INSTALLATION Filed Sept. 6, 1921 2 Sheets-Sheet 2 Patented May 22, 1928.

'l ATENT OFFIC E AR1\TOLD PFAU, 0F MILWAUKEE, W-I'SCQNSIN, ASSIGNOR 'TO ALLIS-CHALMEBS MANU- FAGT'UEING OMPANY, OF MILWAUkEE, Wisconsin, A

"WARE.

CORPORATION OF DELA- HYDROE LEGTRIC INSTALLATION.

Application mease tembere, 1921, Serial no.

This invention relates in generalto power installations, and it has particular re1ation to hydro-electric powerinstallations where the hydraulic machine is operativexunder'or agai'nst a widely varying head.

Turbines of hydraulicpower plants which are subject toa highly variable head such. for instance, as thehigh and low tide of the ocean, suffer a considerable lossin the power developed, This is particularly the case with verylowheads where even a slight change ill the head amounts to quite-a considerable portion of the full normal head. For instance, if the normal net head is 4.5 meters. the highest head 6 meters, and the lowest head t'wo meters, the total average amounts to 4- meters or 88.8% of the normal head. b

It is well known that the; number of revolutions or speed of a turbine varies with the square; root of-th'e net head. For instance, if the revolutions are 100'per minute on'the 16, meters head,it is I-OOdiVided by /fZj-or about 71 revolutions under 8 meters, -andit s 100 divided by or 50 revolutions, that half of theformer amount when the head a: dropped to A of the maximum head.

I aturbine is directly connected to an alternating currentgenerator, it should, alwas operate 'at't he same number of revoluas, otherwise the numberof periods or frequency of the current would change, and this would render parallel operation with other generators impossible. Therefore, if a turbine were normally designed for '100 revolutions under 1 16 meters net head, it would'have to develop under 4 meters-head, not 50 revolutions, buttwice as much, that 100 revolutions,-'in orderto produce 'current of the proper numberof periods or frequency. A turbine operating at a speed which'is 100 per cent *hi'gherthan normal, however, shows such unfavorable hydraulic efficiencies that it becomesuncommercial to still nse a turbine for "such operating conditions.

The speed of the generator could-beimainrained normal by using'in steps belt drives 498,720, and in Switzerland September a, 1920.

or similar devices with proper transmission ratios. This arrangement, however, is impossible'where large units are used and particularly when the turbine'and generator are directly coupled, whichis the'most favorable mechanical solution.

The power developed by the turbine is The capacity or power of the turbine, however, is also subjected to a variation'in the efficiency of the turbine, and this deviates'mo're from thebest value as the number of revolutions or speed is greater or less than the normal speed.

Therefore. if the power or capacity, for instance, under 16 meters net head, is 4000 H. PM. then it is, according-to the above formulae, only 500 H. P. under 4 meters,

and this does not as yet consider the loss of power due to reduced eliiciency. Now, if the turbine must maintain its 100 revolutions,it would have to run twice as fast as is necessary in order to maintain its normal efficiency. Therefore, the efficiency will drop tosnch extent that nothing will be left of the 500 H. P. In other words, the'turbine willproduceno power and, therefore, represents a dead capitalinvestment.

For medium or-high variable heads or, in general, for conditions which permit of the use of horizontal shaft units, the problem of the economical utilization of head can be solved by arranging the hydraulic parts in two separate hydraulic elements, one located on each side of the generator. The Francis turbine which applicant has disclosed in United States Patent No. 1,023,585, dated April 16, 1912, and which is a double overhung Francis turbine, can be employed in such a manner that one side utilizes the high head and the opposite side utilizes the low head. In this case, the absolute number of revolutions of the two turbine sides are naturally the same, whereas the individual capacities of the turbines are selected in accordance with the corresponding heads and quantities of water required to suit the capacity of the generator.

Horizontal shaft units can not well be employed for widely variable low heads for several reasons; therefore, in such cases the arrangement of twoturbines can not be practically employed, particularly in cases where direct coupling to the generator is required.

The constructions for which patent is herewith applied, includes such as provides a suitable solution of the problem, inasmuch as there are employed, not two different turbines, but rather two diiierent generators. This may be seen from the accompanying drawings, especially Figure 1, the drawings disclosing an embodiment of my invention, various novel features of which will be apparent from the drawings and the description herein considered in connection therewith and will be more particularly pointed out in the claims.

In the accompanying drawings Fig. 1 is a partly sectionalelevation of a hydroelectric installation embodying features of this invention.

Figs. 2 and 3 are schematic showings of a speed-controlling governor and its method of operation.

i a2 poles.

Inaccordance with the disclosure of the drawings, the turbine A is directly coupled with the electric generator unit B, made upof the generator elements B and E and the exciter C. All rotating parts of this unit are carried on the thrust bearing D. The turbine may be automatically controlled by a governor acting on the regulating shaft E.

The generator B consists of a rotor fixed on the main shaft and having two sets of poles B, andB so arranged that the set B,

produces the required number of periods or frequency p at a speed a and a number of poles m, and the other set 13 produces the same number of periods p at aspeed a and Similarly, two separate stator elementsS and S, are provided, corresponding to the two sets of poles l3, and 13,, respectively, the field element B and the stator S constituting the generator B, and the field element 13 and its stator S constituting the generatorB The exciter O is so dimensioned that it furnishes current for either one of the two alternator sets.

Let us now assume that the turbine is to utilize any head between the limits H and H Assuming now that this head is divided in two heads, h and h, in such a way that h varies between the limits H, a maximum, and H a minimum, and it varies between the limits H a maximum, and H, a minimum. For each of these two heads, h and h, the most favorable speed a and n of the turbine is so selected that the desired uniform frequency 7; is obtained with the corresponding even number of poles. For instance, if the best speed of the turbine for head It be 150 and for head it be 120,- then pole set E, has 40 poles and the other pole set E, has 50 poles, if current of a frequency of 50 cycles per second is required.

Under the low head it, the turbine naturally develops less power at full gate than it does under the high head it, therefore, generator B, can be designed for a correspondingly smaller capacity in order to operate at best eficiency.

The speed of the whole unit A BC.D can be held within desirable limits by an automatic governor of known construction. If the governor is driven mechanically, that is, if it is driven from the main shaft directly, then two transmissions must be provided, corresponding to the two diiferent'speeds a and a of the turbine, for instance, two belts with corresponding pulleys and couplings.

Another method for controlling the two speeds n and n can be seen from Figures 2 and 3 and can be accomplished in the manner described hereinbelow. 1

Figure 2 shows schematically a servo-motor M of well known construction, such as is used for controlling the guide-vane openings of turbines. The regulating valve V receives fluid pressure, as indicated at K, and admits same, according to the position of the regulating valve piston V eit-her to a passage K, communicating with the front side of the regulating piston M of the servo-motor M, or to a passage K communicating with the rear side of the regulating piston M The motion of the regulating piston M is transmitted to a relay R. A speed governor P receives its revolutions through a drive T from the turbine shaft and transmits the motion of the shifting collar or stud of the governor to the floating lever V-P-R. As soon as the regulating valve piston V is raised out of its mid position, fluid pressure K reaches the front side K, of theregulating moving the latter until the regupiston M lating valve piston'V is brought back to its former mid position. This is attained by the relay R and the floating lever R-P-V in such a way that the forward mot-ion of the regulating piston M, produces an upward motion of the end R of the floating lever, causing the regulating valve piston V, to be lowered after it had first been raised by the speed governor. I

The corresponding strokes of the collar of is the total length of between the relay valve V.

thespeedgovernor P produce strokes?" and fan the relay in thefol-lowing proportion:

where f and) are strokes of the relayR corrcspondingto strokes and s, respectively,

'of'the collar of the speed governor-P, and

(PV) is the length of that portion of the floatingulever between thespeed governor P and theregu'lating valve V, and (RV) the floating lever B, and the regulating :To-each position of the collar there corresponds a certain number of revolutions or speed of'the speed governor, if the design of the. latter is static. If we assume that the revolutions or Speed corresponding to the highest'position of the speed governor is m, as shown in the diagram of Figure 3,

that of the mid position u and that ot the lOWVBSUpOSliZ'lOIl n then the value is conventionallytermed the totaldegree of speed variation ofthe speed governor; and f the values where I d is the degree of speed variation between speeds n, and andn or correspond ing positions of the governor collar, and d is; the degree of variation between speeds a and 72,, or corresponding positionsof the governor collar. These values d and (Z then indicatethe corresponding degrees of speed variation of thepart strokes of the collar of the speed governor, or of corresponding relay strokes f and f. WVith reference to the .generally'termed active strokes of the speed governor, that is, the strokes necesregulating piston a By shifting the hand wheel R along the relayrod R in upward or downward direction, these active relay stroke-s f and can be; distributed at will over the whole stroke sa ?y for producing the total stroke of the F, Figure 3. From this it follows that the speeds n and n, or the mid positions of the corresponding active strokes of the speed governor, as indicated in Figure 3, are such that these corresponding mid positions are located within the totalstroke ofth'e speed governor produced y the speeds n and n and this consequently controls the corresponding speeds of the turbine.

, (Figure 2), around the mid position of the relay.

If the total stroke of the collar of the speed governor is selected large, as also-the corresponding difference in the speeds a and n that is, the corresponding degree of variation of the speed governor is thenitispo'ssible to control by the same governor for the speeds wand '12, of the turbine A (Figurel) pertaining tothe two generator units 'B 'and B According'to the selected position of the hand wheel R, we can, therefore, regulate For example: Assume that at l()%, Z"=d=6%, n 150, and 1/ 120: then 1%,, 135 and from formula (3), we obtain )z =15 l-.5, and n =ls 5.5 from formula we obtain n =1 23.{3, and n =1l6.4rfrom formula (1), we obtain m=162, and n =l0S. The spaces 1, 2, 3 and a, indicated in Figure 3, therefore, correspond to differences in numbers of revolutions of 7.5, 10.5, HA, and

tion of the end R of the lever VP'R on therelayrod R a hand wheel R heing the specific means shown for securing the desired result.

The springs of the governor-are ofsuch strength as to produce the desired governing eti'ect through a wide active range, to thereby obtain a regulating effect that produces a plurality of constant speeds of the'turbinc, these speeds corresponding to different settings of the hand wheel R 'on the'rotl'R his desired regulation is such that thefull stroke of the regulating or compensating 'mechanism, such as the valve V, of theservomotor, corresponding to the full stroke f, f in eltherdirect on from such normal speeds, corresponds to only partial stroke of the governor fiy ball device, the effect being such as to 'produc'e constant speed independ entlyof a variation in the load ofthe'tur;

bine between substantially no load the desiredliinit of overload; and in this d'es'red regulation to produce speed'atvariable load is ainabl any one of widely variant operating speeds, such as might correspond to operation of the turbine under conditions of vari ble head. I

Vhile the hydro-electric unit described above finds great utility when connected turbine A and the with aconsumption or distribution circuit whose frequency is definitelyestablished by means other than said unit, nevertheless, it finds considerable utility when it is the only power unit connected to or establishing the frequency of the distribution circuit, for through the means described for maintaining-a plurality of definite operating speeds for the generating element, the unit is readily operative to furnish a supply of elect-rical power to such distribution circuit at the desired definite operating frequency. It may also be remarked that a combination B B C canbe so arranged that A serves as a pump instead of a turbine in which case B, and'B serve astwo corresponding motors instead of generators in such a way that the fact that the electrical part B -B has two different operating speeds permits operation of the pump to produce two different lifts.

It may furthermore be remarked that the generator elements B -B of such a unit'could beso built that A acts'as a turbine, firstrotatingin-a given direction and delivering electrical energy with one of the two generatorsB or B,

transforming such energy, under the speed n or n, respectively into electricenergy of tion opposite the constant number of periods of frequency 1), or that the turbine rotates in a directo the former and operates as a pump absorbing energy which is furnished by the motors 13 -13 formerly operating as generators, the energy supplied to the motors being atthe common frequency but the motors operatingat the different speeds n v and n respectively.

' quency It should be understood that the invention is not limited to theexact details and construction shown and described, for obvious modifications will occurto one skilled in the art.

It, is claimed and desired to secure by Letters Patent: I

1. A hydro-electric unit for operation under conditions of widelyfvarying head,vcomprising a hydraulic: machine operative at two different normal speeds dependent upon the variable net head,fand an electrical eleinent comprising two alternating current dynamo-electric machines operatively connectible to said hydraulic machine to provide for transfer of energy in either direction between either of said dynamo-electric machines and said hydraulicmachine, said dynamo-electric machines being operable to produce electrical energy ofthe same frewhen each is driven by said hydraulic machine operating at a different one of said two normal operating speeds.

2. A hydro-electric unit for operation under conditions of widely varying head, comprising a hydraulic turbine operative at two speeds.

vdifierent normal speeds dependent upon the variable net head, and an electrical generator element comprising two alternatingcurrent generators operatively connectible to J said hydraulic turbine to be driven thereby, said generators being operable to produce electrical energy of the same frequency when each is driven by said turbine operating at a different one of said two normal operating pump of the rotary impeller type at two different normal speeds dependent upon the variable net head, and an electrical element comprising two machines operable as alternating current motors each of said motors havinga synchronous operating speed different from that of the other and operatively connectible to said hydraulic machines to drive the latter as a pump at one of said two normal speeds.

at. A hydro-electric unit for operation under conditions of widely varying head, comprising a hydraulic machine operative either a turbine or a pump of the rotary impeller type at two different normal operating speeds dependent upon the variable net head, and an electrical element comprising two alternating current dynamo-electric ma chines each operative either as a generator or a motor and operatively connectible to said hydraulic machine to provide for transfer of energy in either direction between said hydraulic machine and either of said dynamo-electric machines, said dynamo-electric machines beingl'operable as generators to produce quency only when each, is driven by said hydraulic two normal operating speeds.

machine at a difierent one of said electrical energy of the same fre- 5. A hydro-electric unit for operation undifferent normal speeds dependent upon the variable'net head, an electrical element C0lI1- lit) prising two alternating current generators operatively connectible to" said hydraulic turbine to be driven thereby, said electrical element being operable. to produce electrical energy of the same frequency when driven by said turbine operating at. different ones of said two normal operating speeds, and a speed-controlling governor'for said turbine having a wide degree of speed variations;

said governor being provided with shiftable collar having a large collar stroke and having associated therewith a compensating servo-motor, the active stroke of said speed governor required for the controlof said compensating servo-motor being only as fraction of the total collar stroke, whereby two active collar strokes maybe utilized di- A head, and the lower part ofthetotal collar stroke forthe region of tlielower speed corcrating speeds of saldgenerators, namely,

the-upper part of the collar stroke for; the region of the higher speed corresponding to operation] of the turbine under th higher responding to operation of the turbine under thelower head. e. a a

6. A hydroselectric :installat-ion for operation under conditions of Widely varyinghfead, comprising a hydraulic machine operative at two different normal speeds dependent upon the-variable not head, and an alternatingcurrentvdynamorelectrie unit openable as motor or generator with different numbers of field-poles;and: operat vely connectible: to said hydraulic machine, said .dy-

nan1o+electric UHiFbGlIlgrOPfiI'ttblQ to pro-- duce electrical energyofthe same frequency when. driven at'diiferent ones of said two normal operating speeds.-

7 The method of operating a hydro-electrio machinehavingaplurality of alternators associatedytherewith, which comprises, utie li'zingone .of'said alternators to maintain predeterminedufrequenoy fora definite range ofspeed :of-said machine, and utilizing another of i said ;alter.nators to maintain the same frequency for a different definite range of speed of said machine:

8: The method of goperating a hydro-elem tric machineprovidedswith arspeed governor having a long range-of regulating motion and having a: plurality, of alternators associated therewith, Which comprises,- vutilizing one-of said. alternatorswh'ile limiting the extent. of active regulating. motion. of said governor: to an increment 0f its; range to produce constant-frequency for said increment variation in speed, andutilizing another of said alternntors. While 'limiting the extent of active regulating motion ofisaid governor to, another increment of .its range to produce the; same frequency for said other 'iincrement variation: in Speed.

9. A hydro-electric unitfor, generation of alternating currentiof substantially ,constant frequency under conditions of widely varying head on: the turb ne element of {the unit, comprisin allydraulic turbine element operative at. a ,imite plurality of speeds dependent upon-the headtthereon, an electrical supply unit comprising a; dynamo electric said eleetrical supplyinnit is :caused to pro duce electrical fener frequency indepen ently of the particular one bfsaid speeds at which said I turbine of a desired; constant a particular one of said speeds of operation of fixed speed ratio, said generating element being operable to produce electrical energy of a desired constant frequency independe ently o-f the particular one ofsaid speeds at which said primemover operatesto, drive saidgenerating element.

11. A- power'installation for generation of alternating current of substantially con: stantofr'equeney under conditions ofvarying supply of energy available and consequentvaryingspeed, comprising a prime mover operative, atdifi'erent normal speeds dependent upon, the energyavailableat said prime mover, and an alternating current generating unit including means for insure ing operation of said unit with different num-v bers of efiective field poles, said generating unit; being operable to produce, electrical energy of said desired frequency when driven by, said:prime mover operating at saidadiiferent speedsand utilizing appropriate ones ofsaid numbers of poles.

12. A power installation for generation of alternatingcurrent of substantially constant frequency under conditions of widely varying supply of energy, comprising an alternating current generator unit comprising; a synchronous dynamo-electric machine, aprime mover mechanically connected to said-dynamo-electric machine and operable to; drive said dynamo-electric machine at a finiteplurality of-dilferent speeds dependwhich saidprime ,mover drives isaid ldynamo-electric machine.

13. A power installation for production of alternating current of constant frequency under conditions-of variable available supply-of motive energy to said installation, comprising a prime mover operable froma source of variable available supply of energy 7 and operable ,at a finite plurality of speeds, an

alternating current generating: unit including aadynamovelectric machine connected to said prime mover through a driving connecelement operates; said-imeans including de- 1 vices selectively voperative to: maintain a a tionnof fixed speed ratio, and'means for regulating saidprime mover to cause it'to maintain itself in operation at any one of said speeds, said generating unit being capable of producing alternating current of said constant frequency when said prime' mover is operating at different ones of said speeds. I p

14. A power installation for-p roducti on of alternating current of constant frequency under conditions of variable available supply of motive energy to the prime mover of said installation, comprising a prime mover operable from a variable supply of motive energy at a finite plurality of speeds dependent upon the supply of energy available, an alternating current supply unit comprising an alternating current dynamoelectric machine operatively connected to said prime mover to be driven thereby at different predetermined speeds dependent upon the speed of operation of said prime mover, and means for causing the speed of said prime mover to be maintained constant at any one of said speed values, said supply unit being operable to supply alternating current of constant frequency independently of the particular one of said speeds at which said dynamo-electric machine is driven by said prime mover.

15. The method of operating an electrical power installation including a prime mover'operable under conditions of Widely H frequency varying supply of energy therefor, and an alternating current dynamo-electric generating unit arranged for operation by said prime mover with diflerent numbers of field poles, which comprises utilizing said alternating current generating unit under operation with one number of field poles to maintain a predetermined frequency over a definite range of variation in the supply of en ergy' for said prime mover, and utilizing said alternating, current generating unit under' operation with another number of field poles to maintain the same frequency over another definite range of variation in the supply ofenergy for said prime mover.

16. A hydro-electric installation for'the generation of alternating current of constant under conditions of variable availablehead and varying speed of turbine incident thereto, comprising an alternating current dynamo-electric generating unit, a sourcelof water supply of variable available head and a hydraulic turbine operable from said source to furnish energy for driving the rotary magnetic element of said dynamo electric unit at a controlled speed dependent upon the available head of said source, and

means for insuring thesupply of electrical energy by said dynamo-electric unit at a predetermined fixed frequency independently of the particular one of said speeds at which the rotary magnetic element of said dynamo-electric unit operates, said latter means including devices selectively operative to maintain any particular one of said oper ating speeds. Y c '17; A hydro electric installation for'operation'under conditions of substantially cone stant frequency and Widely varying head, comprising a hydraulic machine operable at diiierent predetermined normal speeds dependent upon the head on said machine, a synchronous alternatingcurrent dynamoel'ectric unit the rotatable magnetic element of which is operatively connected to said hydraulicmachine for operation therewith, a distribution circuit the frequency of WhOSQ: current is definitely established-by means other than said unit, and means for insuringthe operation of-the rotatable magneticvelement of said dynamo-electric unit at a plurality of synchronous speeds while said dynamo-ele'ctric unit is connected in power relation with said distributioncircuit.

' 18. A power installation for the production of alternating currentlof constant fre. quency under conditions of widelyvarying supply ofenergy and varying speed-of prime mover consequent thereto, comprising a' synchronous alternating current generator unit, a prime moveran'echanically;con nected to the rotatable magnetic element of said unit and operable to drive said magnetic element at different speeds dependent upon the supply of energy available, a distribution circu t carrying current of a frequency definitely established by means other than said generator unit, and means operative to insure the supply of electrical energy from said generator unit to said distribution circuit at the frequency of the latterindependently of the particular one of said speeds at'which the rotatable magnetic element of said generator unit is driven by said prime mover.

19. The method of regulating a hydroelectric installation comprislng a hydraulic turbine, an alternating current generatmg unit,- and a speed governor having a long range of regulatingmotion, which comprises limitingthe extent of active regulating motion of said governor to'an increment'of its range to produce a predetermined controlled speed of operation of said turbine, and limiting the extent of active regulating motion of said governor to another increment of its a second controlled speed range to produce of operation of said turbine, andchanging from one to another of said-particular ranges of regulatingwmotion in accordance with variations in a predetermined condi tion attendant upon the operation of said turbine. r

20. The method of controlling a hydroelectric unit comprising a'hydraulic turbine subject towidely varying head to cause said turbineto operate at any one of a plurality of substantially constant speeds independently of variations in load on said turbine, which comprises utilizing a speed governor of Wide eifective speed range, and compensating for the operating efiect of said governor to cause the maintenance of any one of said constant speeds during a relatively small part of the total range of said governor, and changing from one to another of said speeds of operation of said turbine in accordance with variations in the available head on said turbine.

In testimony whereof, the signature of the inventor is afixed hereto.

ARNOLD PFAU.

CERTIFICATE 0F eemmenem.

Patent No! lie/wee.

ARNOLD PFAU.

It is hereby certified that etros apgaears in me minted s 2 above numbered paient requiring eorreetien as ieilews: Page 4 e 3, for the Wfiid "machines" teed "machine"; same page, Eiee the Word "variatiees" reed "variation"; page 5, line 57 word "thereby" strike out the comma; page 6, Zine "head" insert a. cemma; and that the said Letters Peeee these cerreetions therein that the same may cenfem m tie reeer in the Patent Office.

. Signed and sealed this 3;"; day of July, A. D: wee.

Iii, 3. lvieere (Seal) Acting fiemmissieszer 0:? Fefieets.

CERTIFICATE OF eeRREeneN.

Patent No, tfevtees. Granted May 1928, to

ARNOLD PFAU.

It is hereby eettitied that error aegreers in the etinted seeeifiee of the above numbered patent requiring eorreetien follows: Page tin; elaim 3, for the ward "maehines" reed "machine"; same page time 32th *in the word "variatiens" read "variation"; page 5, time 57, eieim 9 word "thereby" strike out the comma; page 6, time 54, elaim 16, atte "head" insert e comma; and that the said Letters Pateet sheetd he with these eerreetions therein that the same may conferm te the reeefe 0f the ease in the Patent flffieee Signed and sealed this 3rd day of July, A. D2 1928.

er the the word M. J. MOQIE, (Seal) Acting Gemmiseioner of .Jeteets.

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