US1843724A - Electrical regulating system - Google Patents

Description

Feb. 2', 1932. H NKEN 1,843,724

ELECTRICAL REGULATING SYSTEM Filed April 18, 1930 CURRENT IN COIL AMPERES PHASE VOLTAGE PERCENT. Inventor:

Lawrence H. Juhken,

His Attorney.

Patented Feb. 2, 1932 LA'WBENGE H. J UNKEN G1 HAZDBQnMl na W J ASSIGNOE ELIE-CE TRIO COMPANY, at. GSEK-PQRATL'UEE' {BF NEW Application filed April 18,

My invention relates to electrical regula tors and regulating systems and particularly to voltage regulators which are associated with polyphase systems.

5 Electrical regulators when associated with a a polyphase system were originally connected to the system in such a manner that they were responsive only to variations in the regulated condition occurring in one of the phases. So long as the system was balanced this proved perfectly satisfactory but when the system became unbalanced, as through the occurrence of a single phase short circuit, the regulator might or might not respond in the proper manner de ending upon how the partlcular phase to W ich the regulator was connected might be afiected by the unbalanced condition.

It is well known that a single phase short circuit on a polyphase machine, such as a three phase alternator, will tend to produce conditions of instability. Formerly this was not especially serious but in recent years, due

to the trend toward longer transmission lines and increasing interconnections between systems or for economic reasons, synchronous systems are being operated closer to their limits of steady state stability with the result that the marginal increase in load which may be added to a system without causing the machines to break out of synchronism has been steadily decreasing.

The fact that voltage regulators associated with synchronous machines operate to increase the breakdown torque of these chines, through their action in increasing the excitation and hence the electromagnetic bond between the rotor and stator oi the ma chines, in their effort to maintain constant voltage is also well known. llhus from the point of view of system stability and transient conditions under short circuits it is important that the voltage regulators should respond not only to variations in the voltage of balanced systems, but they should also act to increase the excitation of their associated machines as a result of unbalanced voltage conditions. i

This problem may be attacked in either oi 50 two ways; namely, one, by devising a special 1830. serial no. 2415,4515;

polyphase device which may be connected directly to the polyphase line for actu: the regulator in the proper manner spouse to both balanced voltage variations and single phase variations or, two, by inserting between the ordinary actuating means of the regulator and the polyphase circuit an intermediate network which applies to the ordinary regulator actuating means a voltage which varies in proportion to ballanced variations and which also varies in the proper manner in response to unbalanced conditions of the circuit. My in vention relates to the latter way and accordance therewith i provide means for impressin on the ordinary operating means of a regulator a voltage which is the arithmetical sumcf a plurality of in phase monic voltages which are individually proportional, but not necessarily directly proportional, to the difierent phase voltages of the system.

An object of my invention is to provide a new and improved regulator and regulating system which will produce a proper regulating action, when operated in conjunction with a polyphase circuit and polyphase dynaino electric machine, in response to variations in both the balanced polyphase electrical condition being regulated and single phase variations of said condition.

Another object of my invention is to pro vide new and improved means which when associated with a translating device such as the ordinary operating meanso'f a conventional electricalregulator will cause it to re spond properly to both balanced and unbalanced variations in a condition of a polyphase circuit.

A further object of my invention is to provide a new and improved highly sensitive electrical regulator on which the effect variations in the electrical condition being regulated varies at a greater rate than does the regulated condition itself.

My invention will be better understood from the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

till

In the drawings, Fig. 1 is a diagrammatic showing of an embodiment of my invention.

Fig. 2 is a set of comparison curves for illustratmg balanced polyphase voltage variations of cir-' contact 15 whose movement is governed the increased sensitivity of my regulator and Fig. 3 illustrates another embodiment of my invention.

Referring now to Fig. 1 of the drawings in which I have shown as the polyphase dynamo electric machine to be regulated an alternator 1, although as the description of my invention proceeds it will become obvious to those skilled in the art that my invention is equally applicable to the regulation of other polyphase dynamo electric machines, such as synchronous motors or synchronous condensers. Alternator 1 has an armature 2 which is connected through brushes 3 to a load circuit a on which, for purposes of illustration, it will be assumed that it is desired to hold constant voltage. The field winding 5 of the regulated machine is energized by the usual shunt wound exciter 6 which has an armature 7 and a field winding 8. For varying the excitation of the exciter and hence of the re ulated machine a resistance 9 is connected in t e field circuit of the exciter 6 and is arranged to be controlled by the action of the regulator 10.

Regulator 10 has been shown as of the conventional vibratory contact Tirrill type, but any regulator which has a main control element such as an electromagnet or. contact making voltmeter is suitable for use with my invention. This regulator includes the usual vibratory contacts whose movement is governed by the antihunting coil 12 through the usual system of levers 13. Anti-huntin coil 12 is connected across the exciter 6 an its pull is balanced by the usual system of springs which are represented by spring 14. Theother contact his main control 16 through the usual system of levers 17. Dashpot 18 serves to dampen the motion of this contact.

The usual practice, as already referred to, is to connect coil 16 directly across one of the phases of circuit 4 when it is desired to regulate voltage. However, as previously pointed out the regulator is then responsive to only one of the voltages of the circuit with the result that the re ulator may fail to increase the excitation o the regulated machine when a severe unbalanced single phase load is thrown on it.

In order to make coil 16 responsive to single phase voltage variations, as well as to cuit 4 I provide a network 19 which in the embodiment of my invention illustrated comprises essentially a polyphase iron core transformer having a primary winding 20 and a secondary winding 21 which is open mesh connected, or, as circuit 4 is a three phase circuit, more specifically open delta connected. It is material to my invention in its broadcomprising contact 11.

. ages of est aspects whether primary winding 20 is mesh connected or star connected, but it is important that the transformer be so de-- parting from my invention. in its broader aspects. Operating coil 16 is connected across the open terminals of secondary winding 21. A. condenser 22, which may or may not be adjustable as desired is connected in the circuit of core 16 and an adjustable resistance 23 is connected across the condenser 22 for reasons to be explained hereinafter.

In describlng the operation of my invention I will first describe the operation of network 19. Assume that alternator 1 is operating in a normal manner to impress a balanced three phase voltage on circuit 4 and that this circuit is supplying a balanced load. Under these circumstances each of the phase windings of the secondary windin 21 will have induced in it a voltage which is numerically equal to the voltage induced in each of the other phase windings but which makes a phase angle of 120 degrees with each of the other voltages. However, as the core of the transformer becomes magnetically saturated during at least the peaks of the cycle of the impressed voltage the flux wave will beflat top ed even if the impressed voltage is smuso1 al. This is because as the core becomes saturated its permeability decreases so that the rate of change of flux per unit change in instantaneous impressed voltage becomes less, which is merely another way of saying that the slope of the flux wave becomes flatter at the top. As the voltage induced in each secondary phase windin is produced by the rate of chan e of flux in the core this voltage will also be fiat topped.

It is well known that a flat topped voltage wave contains a marked third harmonic. Each of the phase voltages of the secondary winding 21 may therefore be considered as comprising two component sinusoidal volt- Fundamental and triple or third harmonic frequency respectively. As the fundamental frequency phase winding are in phase with their res ective resultant phase volta es it is cleart at their vector sum around the delta is zero for it is fundamental in vector notation that the vector sum of any number of vectors making a closed loop is zero. The triple frequency or third harmonic components in each phase winding are, however, all in phase so that their vector sum around the loop of the delta is equal to their arithmetiare in phase with each other in a three phase system is obvious for if the three fundamencomponents in each a cal sum. Thatthe third harmonic voltages it will drop with the result that the total third harmonic voltage across the opening in the delta will decrease as the voltage is equal to the arithmetical sum of all the third harmonic voltages. This third harmonic voltage, if applied to a regulator will thereforeact in the proper manner to increase the ex citation of a regulated machine in response to single phase voltage variations on the circuit as well as to cause the regulator to act properly in response to balanced voltage variations.

An important consequence of the use of a saturating transformer is that the rate of change of third harmonic voltage in the open delta is greater than the rate of change of voltage on line 4 with the result that any regulator or regulating system employing this -voltage has an increased sensitivity. This may readily be seen by referring to Fig. 2, in which curve 1 shows how the current in main control coil 16 varies with variations in phase voltage whenthe coil is connected directly across one of the phases of circuit t while curve 2 shows the same relation of coil current and phase voltage when coil 16 is connected across the opening in secondary winding 21. At one hundred percent phase voltage curve 2 is considerably steeper than curve 1 thus showing that for equal changes in phase voltage the changes in coil current are much greater when apparatus embodying the principle of my invention is used than when the regulator is connected in the ordinary manner. Curve 1 is a straight line through the origin of the coordinate axes, which of course is as it should be, as it is merely a graphical representation of the single order equation symbolizing ohms law. Curve 2 resembles in shape the magnetization curve of iron with the coordinates reversed. This also is as it should be theoretically, is a measure of the coil current, varies with the saturation of the transformer core which, of course, varies with variations in the magnitude of the peaks of the phase voltage.

It is interesting to note that the slope of curve 2 becomes flatter towards the top. This is thought to be because as the phase voltage increases the knee of the saturation curve is really passed at the beginning of the voltage Wave instead of at the peaks only so that the flux wave becomes less flat topped with the result that the third harmonic voltage decreases.

Although the voltage across the opening of the open delta connect-ed secondary winding 21 may be made to operate a regulator satisfactorily when directly connected thereto, an improved operation is secured through the adjustment of condenser 22 and resistance 23 so as to partially neutralize the third harmonic inductive react-ance of the operating coil circuit. This has the double adfor the third harmonic voltage, whichvantage fundamental frequency which might tend to flow in the circuit under unbalanced conditions.

Keeping in mind that coil 16 is energized by a voltage which varies in proportion, but not in direct proportion, to variations in the balanced voltage of circuit 4 and which decreases when the voltage of one or more of the phases of circuit 4 decreases I will now describe the operation of my regulating system as a whole. First, however, it should be noted that although I have shown and described an arrangement by which coil 16 is responsive to voltage conditions of circuit 1 my invention is not so limited and that it cannot but occur to those skilled in the art that primary winding 20 might be connected to circuit 4 in many other ways so as to be responsive to other electrical conditions of that circuit, such as current, through the use of a suitable polyphase current transformer, without departing from my invention in its broader aspects. Returning now to the operation of my system as a whole and assuming that conditions in circuit a are stable it will be seen that antihunting contact 11 is vibrating rapidly for the following reasons. When contacts 11 of making the impedance of the cirand 1.5 are in engagement part of resistance a 9 is short-circuited thereby increasing the lield current of exciter 6 and raising its terminal voltage. This in turn causes the pull oi": coil 12 to increasewith the result that lever system 13 causes contact 11 to become disengaged from contact 15. This reinserts the resistance 9 in the shunt circuit of field winding 8 with the result that the exciter voltage falls, causing the pull of magnet 12 to decrease so that contacts 11 and 15 reen gage. This action, as is well known, is ver rapid. and does not produce appreciable pu sations in the current of the alternator held 5. It now the energization of main control coil 16 varies, in response to variations in voltage on circuit 4, contact 15 will be moved up or down by the lever system 17. Thus if the energization of magnet 16 decreases as a result of either a balanced or a single phase fall in voltage of circuit 4 contact 15 will rise, thereby reducing the ratio of time open to time closed of contacts 11 and 15 and increasing the. average excitervoltage and hence the average excitation of machine 1. Likewise, if contact 15 descends this ratio is increased to decrease the average excitation of the exciter and alternator.

While I have shown and described particular embodiments of my invention it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. In an electrical regulating system, a polyphase circuit, electromagnetic means connected to said circuit and electromagnetic means, inductively coupled with said first mentioned electromagnetic means/ for producing a voltage for regulating purposes which is equal to thesum of as many, component voltages as there are phases of said cir cuit, each of said component voltages having a harmonic frequency of the fundamental frequency of said circuit.

2. In an electrical regulating system, a polyphase circuit, electromagnetic means connected to said circuit and electromagnetic means inductively coupled with said first mentioned means for producing a voltage for regulating purposes, said voltage having as many components as said circuit has phases and all of said components having a frequency which is equal to the harmonic frequency of the fundamental of said circuit which is in base in said circuit.

3. In com ination, a polyphase circuit, a regulator, and means interposed between said circuit and-said regulator for. energizing said regulator in accordance with the magnitude of a predetermined harmonic voltage of said circuit.

4. In combination, a polyphase circuit, an electrical regulator, including an operating element, andmeans connecting said circuit andsaid operating element, said means producing a voltage which is proportional to the sum of the in phase harmonic voltages of said circuit.

5. In combination, a polypha'se circuit, an electrical regulator including a voltage responsive operating means and means connecting said circuit and said operating means, said connecting means applying a voltage to said operating means which is equal to the sum of a plurality of in phase harmonic voltages of the fundamental voltage of said cir cuit, each of said harmonic voltages being proportional in magnitude to the regulated electrical condition in a different one of the phases of said circuit. a

6. In combination, a polyphase circuit, an electrical regulator including an electromagnetically operated main control means and electromagnetic inductive means connecting said circuit and said operating means, said connecting means applying to said main control means a voltage which is equal to the arithmetical sum of a plurality of voltages which are harmonics of the fundamental voltage of said circuit, each of said harmonic voltages being proportional to a difieren phase voltage of said circuit.

7 In combination, a three phase circuit, an electrical regulator including a main control means, means connecting said main control proportional to a different one of the phase voltages of said circuit.

8. In combination, a polyphase circuit, an electrical regulator includin a main control element, a polyphase trans ormer having a mesh connected secondary winding, means connecting the primary winding of said transformer to said circuit and means connecting said main control element across the opening in said secondary winding.

9. In combination, a three phase circuit, an electrical regulator including a main control coil, 3. three phase transformer having an open delta connected secondary winding, means connecting the primary winding of said transformer to said circuit so that the phase voltages of said winding are responsive to variations in the re ulated condition in their respective phases 0 said circuit, and means connecting said coil across the opening insaid secondary winding.

it In combination, a polyphase circuit, an electricai regulator includin a main control eiement which is adapted 110%)6 responsive to variations in an electrical condition of said circuit, a polyphase iron core transformer having its secondary winding mesh connected, means connecting the primary winding of said transformer to said circuit so that the voltage across each phase winding is proportional to the magnitude of the regulated condition in a different phase of said circuit, said main control element being connected in series in the mesh-connected secondary winding, the magnetizing current of said transformer being high enough to saturate the iron core.

11. Means for producing a voltage for reguiatory purposes of polyphase systems which varies in the proper manner for both balanced and unbalanced variations in the magnitude of the regulated condition and which aiso varies at a rate greater than the rate of variation of said regulated condition comprising a polyphase transformer having a no load magnetizing current sufficient to at least partially saturate its core and an open mesh connected secondary winding across which opening appears said regulatory voltage.

Means for producing a. voltage for regulatory purposes which varies in proportion to variations in the arithmetical sum of the phase voltages of a three phase circuit but at a greater rate than said variations comprising a three phase transformer having a no load magnetizing current sufficient to at least partially saturate its core and an open delta connected secondary winding, said voltage appeering across the opening in said delta.

13. In a regulating system, a polyphase circuit, a dynamo-electric machine connected thereto, a' regulator for controllingsaid dynamo-electric machine, and means interposed between said regulator and said polyhase circuit for energizing saidregulator in accordance with the magnitude of a predetermined harmonicvoltage of said circuit.

14. In a regulating system, in combination, a polyphase dynamo electric machine, a polyphase circuit connected thereto, a regulator associated with said dynamo electric machine, means connecting said regulator to'said circuit, said means including .a polyphase transformer having an open mesh connected secondary windin 15. In a re ulating system, in combination, a polyphase ynamo electric machine, a polyphase circuit connected thereto, a regulator associated with said dynamo electric machine,

means connecting said regulator to said circuit, said means including a polyphase transformer having its primary winding connected to be responsive to an electrical condition of said circuit, an 0 enmesh connected sec-' ondary winding, an 'an iron core which becomes saturated during at least a portion of the cycle of its magnetlzing current.

16. In a regulating system, in combination, a three phase alternatona three phase circuit connected thereto, "a voltage regulator associated with said alternator, said regulator including a main controlmeans, means conent phases of said circuit, said components differing in frequency from the fundamental frequency of said circuit, and means connected to be responsive to said quantity.

20. In combination, a poly hase circuit, means connected to said circuit or producing an electricalflquantity whose frequency is a multiple of the fundamental frequency of said circuit and whose magnitude is equal to necting said control means to said circuit ineluding a three phase transformer having its primary winding connected across said line and its secondary winding open delta connected, said main control means beingconnected across said open delta.

17. In a regulating system, in combination, a three phasealt'ernator, a three phase circuit connected thereto, a voltage re 'ciated with said alternator, said regulator including a main control means, means con necting said main control means to said circuit including a three hase transformer havlator assoing its primary win ing connected to said circuit, its secondary winding delta connected with said main control meansconnected in said delta, and its ma netizing current sufiicient to at least partially saturate, its core.

18. In combination, a polyphase circuit, a translatin device, and means for causing said trans ating device to respond to an electrical uantity whose frequency is difierent from t e frequenc of the fundamentalof sad circuit and w ose m 'tude varies in response to variations in a spondi electrical conditionsof a plurality of the ,p ases of-said circuit.

19. In combination, a l

producing an electrical quantity consisting of I, hase circuit, :means connected to said c rcuit, sald means ction of correa plurality of components, eac of said com-.

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