US1050081A - Line-drop compensator. - Google Patents

Description

V J "PEARSON. LINE DBOP GOMPENSATOR. APPLICATION FILED 001-. 10, 1901.

Patented Jan. 7, 1913.

3 SHEETS-SHEET 1.

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UNITED srarrs ornron JOHN PEARSON, or. SOMERSET; WISCONSIN, ASSIGNOB OF ONE-'THIBD'TOIAHES' E;

WILLIAMSON Ann olvn-six'rn 'ro FRANK. I). MERCHANT, or MINNEARQIJmIMmNE;

sore. mnnmaor COMPENSATOR.

1,050,0 1; Specification of Letters Patent. I Pat te J ,,7,1913;

Application fil ed October 10, 1907; Serial No..396,808l

T all whom it may concern:

Be it. known that I,'JoHN-"PnARsoN, a citizen of the United States, residing at Somerset, in the county of St. CroiX and Statecf Wisconsin, have invented certain new and useful Improvements in Line-Drop Compensators; and Ido hereby declare the following to, be a'full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention has for its object to provide .an eitici'ent compensating means for regu lating an alternating current generator so as to maint-ainconstancy of voltage, was nearly so as possible, at the distributing end of along distance transmission line; and

to this end, my invention consists of the novel means for this purpose hereinafter disclosed and pointed out in the claims.

The desirability of keeping the voltage constant, or as nearly constant. as possible, at the distributing end of an alternating current transmission line has long been well recognized. In practice, however, this has been found to be an extremely difiicult problem. If the transmission line is supplytween current and voltage, onthe line, are

greatly increased, as compared with some other-classes of service. If, for example, the line is supplying simply an-incandescent lighting system, as is common in night service, the power factor will be comparatively highibu't if supplying motors, especially induction motors as is common in day service, the poWer-factor'will be comparatively low. The self-inductance, the capacity of the line, and the ohmic drop or resistance of the line, must also be taken into consideration. Because of all these things taken collectively, practice shows that there is a tendency for. a transmission line to decrease the voltage at the distributing end if the current lags behind the voltage; and to increase the voltage at said distributing end, if the current leads the voltage. The drop in the voltage inci'den'tal to-thelag of thecurrent and ohmic resistance of the line has been most' generally considered, and is generally spoken of as. line drop. So far as I know, no successful means have ever been provided, in the prior art, for the complete compensation of these voltage variations at the dismission line sup lied through a which is of solenoid form and has two coils,-

one for voltage and the other for current, with circuit connections from the main line, and which elements are designed to compensate for I R- losses; or, more loosely stated, they. are intended to compensate for losses due to current and resistance; Thesaid Tirrill regulator does thus take more or less note of variationsin load,;but it does"- not take sufiicient note of power factor changes. The standard Tirrill regulator' will compensate, fairly well, when the, power factor does notvary muchybut, in'cases where the power" factor varies from to percent. the-voltage will vary several percent. at the distributing end of "a transgenerator controlled by a irrill regulator.

I am also aware of the so-called Mers'hoii"v compensator; but where an inductive resistance and ohmic resistance are conn'ectdinparallel, as in the Mershon compensator,

there will be a tendency to increase or decrease the voltage, whenever the frequency changes;- for the reason that, when the fre-.

quency gets higher, more current will pass through the ohmic resistance and less through. the inductive resistance. For this reason, the Mershon compensator cannot, in

'myjudgr'nent, be successfully applied to .'a

Tirrill regulator,- nor to a compound wound exciterg but might possibly be applied to a reading instrument, such, as a' voltmeter, wherein very little current only is needed.

My new compensating means, herein-dis closed, is intended not only to.considerthe PR losses, as in the devices of the prior art, but to takefull note of power factor changes. To this end, I provide means for taking oif current and voltage from the transmission lineand delivering the same at a phase difference increased as compared with the phase difierence on the line, so as to thereby secure a resultant which will be effective for effecting the required compensation, when applied, for example, to the alternating current control magnet of the Tirrill regulator or to third coil on a compound exciter. The said resultant, so secured, may be applied simply to a voltmeter, at the generat mg station, to indicate the voltage at therefer to like parts throughoutthe several 15 views; Figure 1 is a diagram view illus trating my invention as applied to the Tirrill regulator. Fig. 2 is a similar view illustrating my invention as applied to a compound exciter; Fig. 3 is a similar View illustratingla modification as applied simply to a voltmeter and, Fig. 4 1s a phase diagram.

Referring to Fig. 1,'A represents a three phase generator, and A A and A the corresponding wires of a long distance transmission line- The field of said generator A is subject to an outside exciter The, exoiter B is subject to a voltage regulator C.' This regulator G is so nearly identical with the structure of the standard Tirrill regulator that it is suiticient to note the only material difference. S This diflerence is due to the modification made to adapt, the Tirrill regulator to my compensating means, as illustrated in Fig. 1; andto this end, the so-called alternating current control magnet of the regulator C employs only a. potential coil C instead of having the customary pair of coils, andthe resultant from my compensator is delivered to th1s poten tial coil C of said regulator C. C is the direct current control magnet of the Tirrill' regulator. v

The primary. feature of my compensator is what lcall a phase transformer,.but pref erably also includesa compensating transformer. These devices, with their proper circuit connections, will now be described in detail. The compensatingv transformer K, shown in Figs. 1 and 2, has a par of coils K and K one for current and 'the other for voltage so connected t-hat'the current travels in opposite directions there-' through, and between the two is placed a third coil K" which delivers the resultant over the wires 8 and 9 tosaidpotential: coil 0 of said regulator C. .As shown. in Figs. 1 and 2, the coil K is a potential or voltage coil, being connected across the main line by, voltage transformer H, and the wires 4 and. 5 leadin therefrom to the said coil K and is terefore adapted to take from the:main line a true proportion of the voltage, in step with the voltage on the mainline and of a certain phase rela-..

will tion to the current on the main line. As shown in said Figs. 1 and 2, the other coil K? is a current coil. connect ed up with the.

main line, through series transformers D and my phase transformer, which, as shown in Fig. 1, is made up of the parts marked E, E, F and G. The part E is a coil wound on an annular laminated core E and this coil E is tapped at three equidistant-points by the three wires or phase leads 1, 2 and 3 leading from said series transformerseD.

"These wires 1, 2 and 3 deliver to said coil E current which holds a true proportion to oted a sectional contact lever G, the outer or end sections of which are insulated from the central section thereof andmay be made to engage with any desired pair or opposlte members of said taps F, by swinging the total main line current, on all the phases, and which is of a certain phase rela- The parts said lever on its pivotal center. The' saidouter ends of said contact lever Ghave off leading wires marked, respectively, 6 and 7. The said device, composed of the-said parts E, E F'and G, is a'dapted'to take from the main transmission line multi-phase current'or voltage and deliver the same in a single phase over the wires 6 and 7. With thefcircuit connections as shown, it takes in multi-phase current and delivers the same in a single phase. The wires 6 and 7 connect with the coil K or current coil of said transformer K, the wire 6' connecting directly therewith, and the wire 7 through a switch button F -and anyselected one ofa' series of leads F brought out from differentpoints along the coil K 7 The purpose of the series of leads F is to vary the strength of the coil K as may be required, depending 'on the amount of ohmic drop in the transmissionline. By changing the contact lever G' from one set or-opposite pair of taps F to anotherv opposite pair of said I taps, the phase of the current taken off over the wires 6 and 7 and delivered to the coil K relative to the voltage delivered over the other circuit to the coil K can be changed so as to increase this phase difference-relative to the phase difi'erence on the main line,

so as to t a resultant in the coil K which will be efictive for compensation; or which consider. effectively power 'factor changes onthe main Line. Assuming that the said contact lever;"G has beenproperly I set to thus secure in'the coil K a single phase current of the proper phase difference relative to the current in the coil K, for due consideration of the power factor changes on the main line, and the switch button 7 has been connected the'proper member of Wires 8 and 9 a resultant to the potential.-

coil C of'the regulator- C,.\vhich will be effective to secure the desired full compenm sat-ion. At no load, the E. El. F. in the coils K and K will-be approximately equal, but as the load-comes on, the current in coil K begins to reduce the E. ill. F. in the re- 'sultant coil K just as the transmission line reduces the E. H. F. at the distributin end thereof; and. this will allow the core of the alternating currentcontrol magnet of the regulator U to drop, with the result that the bus bar' voltage Of'l'll generatorwill be raised under the control of said regulator.

lVhen theload falls oil. the reverse actions, of course, take place.

In all cases. in the coil K sl iifted'in phase more than 3'5 180 de rees in the direction that the main .ci:irrcni; shifts when the mainline current leads, or example, the required shift may be 60 degrees more, in'order to make the proper compensation for the powerfacton so changes on the main line as shown in the phase diagram Fig. 4: of the drawings. In this phase diagraimthe curve T represents the phase of the current in the coil. Kt or the one responding to voltage, and the curve T represents the'phase of the current in the coil 1& or the one responding to cur-- rent. on power factor unity. By reference to this diagram, it will be seen that the phase of thccurrent in coil, K is sixty elec- 4e trical time degrees ahead of the phase hf the current in the coil K and that the two are in opposition to a certain extent. This sixty deg'reesof difference on. power factor I unit-y is-due to the position at which the st'alever G of the phase transformer is set; and it is because of this increase of the said phase difference that the resultant in the coil K is rendered effective. Having thus shown the phase displacement on unity power factor, it can readily be seen that as the main line current lags, thecurrent in coil K will also lag and come more nearlv in opposition to the current in the coil K thereby reducing the strength, of the resultant coil K the resultant coil K These 'are precisely the actions required to secure compen- Rdesiredg. The questmhfthen arises nit be: known which is the proper to cction-to.swingthe contact lever G. The er, is that the phasetransformer 1s s desirable to have currenttestcd outand graduated for that purpose, for the particular line where applied. That this can be readily done, may be understood from the following statements. The field of the core E is rotating. Let it be assumed 7 that this field rotates. counter clockwise; that the phase transformer is connected as shown in Fig. 1, and that the power factor of the line is, at a given instant, 1.00 per cent. 'Then swing the lever G one way or the other, until the core, of the alternating". current control magnet of the'reogulator C drops to its lowest point, and mark the position at which the said-lever G stood on the core E This. for example, may. be the g dotted line position of. said lever, as shown in Fig. l. At this, which might be called the first position for the purpose of graduation. the current in the coils "K and R will be in opposite phase, inasmuch as the power factor is 100 per cent. Next, take a reading of the power factor of the-system when the current lags about 30 degrees, and

shift the lever G again, one way or the other,

until the alternating current magnet core of the regulator C again drops to its lowest point. and mark the then positionof said lever on the core E. This may be called the second graduating DOSltlOlL- Finally, take a reading of the power factor of the systemwhen the current leads, about, 30 degrees, and then shift the lever G again, one way or the other, until the core of thee alternating current control magnet again drops to its lowest point and mark the position of said lever G on thecore Eh This may be called the third position for graduating" purposes. Thereafter, by referring; to these three graduation marks on the core E the operator will know, by the position of the contact lever G, when the current in the coil It? is in opposite phase relative to the current in coil K on power factor 100 per cent; and will further know in which direction from this primary graduation the lever G must move for lap; or lead of the current in the coil K relative to current incoil H dotted line position is the one which said lever G would occupy, in my working system, in order to get the current in 'coils K and K in opposite phase, on power factor l00 per cent.

The lever G being adjustable, the samemay be set for any displacement of phase required to secure complete compensation I it'is not deemed necessary to traceth'e 'andthereby' the desired constancy of voltageat thedistributing end of the line." Some systems require and will standa ig'reat'er The compensator, shown 'i'n..Fi'g. 2,-is1identical with thatxshownin ig'. 1, with the'ex-i ception that the core-EP-Jis how'- provided 'With ,twowindings E and. E the former bei'ng connected-to the leads A A A as in Fig. 1, and the'latter hein in inductiverelation to the said winding sothat the two win-dings E and E, are relatedas primary and; secondary respectively, and the onlydifierence in thea-ction is tha't therebya distinct ind'ucedcurrent is- ,afi'ordedior the" coil K instead of current taken-incredirectlyi' from-the main line. In said'Fig. 2, Z- represents the generator, ,the fieldof which is subject. to a compound e'X'citenV; and this exciter Vis regulated by my compensato'r, through-the so-called rectifier R. k The standard connections from such a compound exciter ,V,.and a rectifier R are Well known,

same in detail. It. is deemed sufiicien-t to note the'additions for connecting in my compensator.- To this end, the compound exciter has athird winding W, in addition" to the old or series Winding'Y and the-shunt Winding. X; and which newwinding W etsits '-ci'1rrent, through the rectifier R, roin the res'ul'tant'coil Kfof my ,coinpen s ating" transformer K. They course of .the

current is over the Wires Sand. 9, brushes 10,"

slipiringszll' and 12 of the rectifier, thence through the leads 13 andl l, to the commuta-' tor 15, and thence over the wires 16 and 17 to said coil of the eXciter-V. The wind-'- 'ings X, Y and W, of said compound exciter,v are all Wound in' 'the same direction on a common core; .and consequently each winding ishe'lping theother'to raise or lower the V01 tage of the exoiter'; and h'ence, of the alternator andtransmission-line.- With these connections, therefore, the-coil \V will cooperate With the 'coilsiX' ancPY of said' compoun exciter, so as 'to efiiect compensation .for the voltage changes at: the 'distributmg end of the transmission' line, to thesame effect as the. resultant from the compensator acts through the Tirrill regulator in Fig. 1, assuming that the speed of the generator'Z s constant. Otherwise stated, when the -co1l V is add'edto the' said compound excit er and'connected up with the other parts-otmy compensator through the. rectifier, the said compound excitcr' becomes a w'oltage regulator for the generator Z and 1s prop-. erly compensated'as described.

Referring to Fig. 3,, a modification is 1 there illustrated,wherein the connections ires 6 and L 1s substituted for cooperation with the ant 'n'ularcore Bend the coil E .the'reon.. "1fhe v 1; core L,=with 1ts coil M, may he swung so as to span any desired diameter of thecore E, just as could the contact; 'lever' Ga in the other ..view.' The Wires 1f2 and-'3'. are, in Fi 3, connectedga'cross the main line to, 5

fv'o tage transformers H? instead of to series I transtormers, as in the other' v ews; and

the wires sand 5 are now connected with. the main line through a series transformer 1 2 e d f acro s the -,ma1n line through voltage tran'sformer's,-a'si-n Figs." l and -2. \Vith this" cons truction, the winding 11 on the; pivoted core L delivers current over the. 7' topoints of junction with the wires land 5, and thence the resultant, is taken over the wires 8- and -9' tothe taps S of the voltmeter N. It will thus be seen that the voltmeter N, the secondary o'f-transformer'D and the coil M are in parallel, so

that the-effective volt-age passing through 109 the voltmeter N will be the resultant of the voltages from the transformer D and the coil M. .'I nthis modificatiomafl true propor 'tion' of the voltageiwill" be taken from all. j the phase leads of the transmission line, and

.be transformed and delivered by the a phase transformer in 'a-single phase volta over the Wires 6 and .7, and the phase di ere'nce' of this'volta-ge relative-to t ecu-rrent sup 'pl ied' over the-gwires [-tan d 5 will be in [-110 creased, relative to the base-difference of the-main.line,..a nd may varied, by shi ft. ing the position of said core L, so .as. to get a resultant from said. two circuits: which will be eflectiv e whndelivered through tria wires 8 and 9, either for the pllrposes of compensation or for indicating the voltage at the distributing end of the transmission line. If connected "to "the voltmeter, as s'hown,'the rading'isfgivelr; but the wires 1 S and 9 could be run-to the potential coil C of the Tirrill regulator,'-as shown in Fig. 1, and be used" for regulating purposes.

It will be understood, of course, that it is a great advantage-to know, at the generating station, what 'the voltage is at the distrihuting station. The deviceconnectcd up as shown ,1 Fig. 3 W111 give this reading.

was connected to 'take the resultant from the 0011 K as there shown.

It should be further noted, that the com- I pensating transformer K, shown iii-Figs. 1

and 2, coul d be dispensed with, and the two pairs of wires (4 and 5) and (6 and/7) be applied, respectively, tothe pair of oppositely wound coils of the A. C..control magnet of the standard Tirrill regulator; and theresultant, from the. sald two circuits from the main line, would then take effect on the core of that magnet and give the compensat1onrequired. It is an advantage,

however, to have the compensating trans, former K; because, otherwise the coils of a be located in the. circuit which takes voltage from the main line.

What I claim is:

1. A compensator having two circuits from niulti-phase transmission line, one for voltage and the other for current, and having in the current circuit a phase transformer taking a. true proportion of the cur-- rent of the main line and delivering the same in a single phase, of a phase difference,

relative to the current of the other circuit, n'creased as compared with the phase difference on the, main line. substantially as described.

2. A compensator having two circuits from a multiphase transmission line, one

- for volt-age and the other for current, and

having-in said current circuit a phase trans former taking a true proportionof the current of the mainline and delivering the same in a singlephase, of aphase difference, relative to the current of the other circuit increased to any desired extent, as compared with the phase difference *on the main line, substantially as described. a coil in each of said circuits supplied with current by the circuit to which it is connected, which coils are arranged to act magnetically in opposition to each other, means for adjusting the strength of one coil with respect to the strength of the other, and means for utilizing the resulting magnet-ism to operate a regulating device.

8; A compensator having two circuits from a multi-phase main line, one for voltage and. the other for current. a phase transformed in said current circuit taking a true proportion of the current from the main line'in all. its phases and delivering the same in a single phase, of a phase difference,

relative to' the current of the other circuit,

increased flS-COHIPQI'QCl with the phase difference. on the main line, said phase transformer being adjustable to cause the current to lead orlag to the necessary extent, and means for rendering'the resultant of said two circuits available for indicating or regu; lating purposes, substantially as described.

i. A compensator having two circuits from a inulti-phase main line, one for voltage and the other for current, a phase transformer in one of said circuits taking a true proportion .of the current from the. main line in all its phases and delivering the same in a .dering the resultantof said two circuits available for operative purposes, substan tially as described.

5. The combination with a multi-phase generator, a transmission line and a voltage regulator for said generator,'of two circuits from the transmission line, onefor voltage and the other for current, one of which circuits includes a phase transformer taking a true proportion of the current or the voltage from the main line, in all its phases, and de livering the same in a single phase, of a difference, relative to the current or voltage from the other circuit increased asconipared with the phase difference on the mainline, means for .adjusting said phase transformer to cause the current to lead or lag to the necessary extent, anda compensating transformer having two coils fed from said two circuits respectively, and having also a third coil delivering the resultant of theothe'r two coils to the voltage regulator of said generator, substantially'as described.

6. The combination with a multi-phase generator and transmission line, and 21 voltage regulator for said' generator, of'two circuits from the transmission line,one for volt age and the other for current, one of which circuits includes a phase transformertaking a true proportion of thecurrent from the main line in all its phases, and delivering the same in'a single phase, of a difference,

member of which two coils has a series of leads through any selected one of which theline connections can be made, and which compensating transformer has also a third coil delivering the resultant of said two coils to the voltage regulator of said generator, substantially as and for the purposes setforth.

.7. A compensator. for multiphase trans m ssion systems,-' comprising two clrcuits from the 'main transmission line one for .voltaige and theother for c'urrent,a phase transformer in said current circuit, said phase transformer ncluding an annular core, a coil thereon, and a rotary adjustable member within theannular core, and means forrendering the resultant of-said two circuits available for operative purposes; I

, 8. A compensator for multiphase transmission-systems, comprising two circuits" from the main transmission line one for voltage'and the other for current-,a phase transformer 1 in one of "said circuits, said.

phase transformer o including an 'annular core, a coil-thereon, and. a rotary adjustable -meinberwithin the annular core, and a compensat-ing transformer having two oppo-' sitely Wound coils'fed from -saidtwo circuits,

respectively, and a :third coil'delivering the resultant, of said two coils for regulating effects.

9. The combination with a multiphase generator 'and'tran'smission line and a .voltage regulat r for said generator, of two compensating.-.zircu its from the main tIfiIlS-u mission line, one for Volta I I for current, -a phase transformer n' one of and the other said-circuits, said phase transformer including an annular core, a coil'thereon'and a rotary adjust-able member Within theannular core, and a' compensatlng.transformer halv ing two; oppositely Wound coils fed from. saidtwo'circuits respectively, and a third rent, a phase transformer in the currentcir-' cuit, said. phase transformer including an annular'core havlng a coil thereon, a ser es of co-nductlng-tapson sa1 d co1l-,a rotary ad juistable conductor, arm cooperating with said taps and having leads extending there; from, and a compensating transformer having two oppositely wound coils, one fed fromthe' voltage circuit'and the other from the rotary conductor arm of the voltage transformer, and a third .coil delivering. the

resultant "of said two coils to theyoltage regulator of the generator.

' In testimony whereof I affix mysignatur e in presence oft-W0. witnesses.

JOHN PEARSON.

ltvitnesses M. Roma's,- H. D. KIL'G'ORE.

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