US2179283A

US2179283A - Regulating system for generator driving engines

Info

Publication number: US2179283A
Application number: US218751A
Authority: US
Inventors: Deeg Theodor
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1937-07-16
Filing date: 1938-07-12
Publication date: 1939-11-07
Anticipated expiration: 1956-11-07

Description

Nov. 7, 1939.

T. DEEG REGULATING SYSTEM FOR GENERATOR DRIVING ENGIEJES Filed July 12, 1938 2 Sheets-Sheet 1 INVENTOR 777600 07 2999.

ATTORNEY T. DEEG Nov. 7 1939.

REGULATING SYSTEM FOR GENERATOR DRIVING ENGINES Filed July 12, 1938 2 Sheets-Sheet 2 MEN INVENTOR Theodarfleeg.

WITNESSES:

BY W5 ATTORNEY Patented Nov. 7, 1939 UNITED STATES PATENT OFFHCEI REGULATING SYSTEM FOR GENERATOR DRIVING ENGINES Theodor Deeg, Berlin-Siemensstadt, Germany, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 12, 1938, Serial No. 218,751 In Germany July 16, 1937 12 Claims.

My invention relates to electric ship propulsion systems and more particularly to a system provided with control means for securing continuous stable operation.

Before stating the objects of my invention some explanation of the real problems involved would be appropriate.

The torque of steam turbines is at zero speed of a turbine and rated steam admission (at rated temperature and pressure) substantially equal to twice the turbine torque at rated speed. At approximately twice the rated turbine speed the torque would be equal to zero. Between these three limits of turbine speed the turbine torque plotted against turbine speed follows approximately a straight line.

In ship drives, the turbine torque and its power are determined by the characteristic of the propeller power plotted against propeller speed and the turbine design, (or the selection of the turbine) is, in general, so made as to correspond or fit to the maximum propeller power, namely, to fit the predetermined maximum propeller speed. Any particular ship speed, for mechanical or geared drives, is in general determined by the adjustment of the steam admission, whereby, as long as a speed increase or decrease takes place (with different adjustments of steam admission) up to the rated steam admission, the speed corresponding to the characteristic of the propeller power is obtained.

With turbo-electric drives of ships it is necessary to utilize a governor or rotation regulator which, by reason simply of the magnitude of the rotational speed during reversing of the ship, limits the loading of the damper windings in the propeller motor. Furthermore, the (ship) reversing operation and the synchronization is simplifled by the use of a rotation regulator or governor 40 because the driving machine is at all times immediately available to be interconnected and the attendant need not concern himself with the regulation of the steam admission. After completion of the synchronization the governor speed, or

45 rotation regulator, may, in a simple manner, be used to attain the desired speed. By adjustment or setting of the speed regulator or governor to the desired propeller speed the regulator automatically alters the steam admission to the gen- 50 erator driving machine until the selected propeller speed is secured. The governor moreover maintains this speed always constant regardless of whether the power requirements rise or fall by reason of changes on the propeller resistance 55 caused by the weather or by effects of changes in water head. The governor has the further great advantage of maintaining the rotational speed constant when the motor and generator fall out of step and, therefore, offers an extensive reli ability to the generator driving machine.

The size (or design) of the electric drive is determined by the maximum (propeller) torque occurring at full speed of the ship. Certain possible operating conditions may, however, lead to torques higher than the rated torque and must, therefore, be automatically avoided. Such cases occur, for example, in multi-screw drives when the rudder is moved hard over at full ship speed or at the loss of a propeller at full ship speed. In this case the governor will seek to increase the steam admission of the driving machine until the selected speed is again attained. At such time the danger, however, arises that the maximum permissible torque, the pull-out torque, is exceeded. This danger is eliminated in the invention because the governor for the generator driving machine has a device by reason of which the instantaneous maximum permissible torque may not be exceeded. For measuring the maximum permissible torque an electric instrument is preferably used upon which the actual transmitted torque and the maximum permissible torque act in an opposite sense. The maximum permissible torque may, for example, be measured by a wattmeter instrument, the field of which is influenced by the exciting current of the generator and the armature of which is influenced by the exciting current of the motor. The actual transmitted torque may be indicated by a second wattmeter instrument that is so connected to current and potential transformers of the leads that it is responsive to the expression EIcos) In this expression E represents generator voltage, 1 represents the frequency of the generator voltage, I represents the motor armature current, and the remaining term represents the power factor.

For limiting the maximum permissible torque, in the practical embodiment of the invention, a movable stop may, for example, be used which limits the steam admission to the driving machine. My control instrument may, of course, be designed so as to operate automatically on the governor adjustment instead of on the position of the stop limiting the opening of the steam admission valve. The instrument may also operate to actuate the governor adjustment means indirectly,

One broad object of my invention is to maintain stable operation between a generator and a motor in a power system where the motor is large enough to take the major portion of the generator load.

Another object of my invention is to so control the operation of a prime mover driving a generator that conditions of unstable operation between the generator and a motor coupled to the generator do not arise.

A broad object of my invention in a power system embodying a generator, a prime mover for driving the generator, and a motor is to alter the speed of the prime mover as a function of the diiierence between the pull-out torque of the motor and the transmitted torque.

A still further object of my invention is to control the turbine speed of a turbo-electric ship propulsion drive as a function of the maximum permissible torque and the transmitted torque.

The foregoing statements of the objects of my invention are not an exhaustive recitation of objects but merely illustrative. Other objects and advantages will become more apparent from a study of the following specification and the accompanying drawings, in which:

Figure 1 is a schematic showing of an embodimerit of my invention operating on the adjustment of the steam admission valve;

Fig. 2 is a schematic showing of my invention in which the control is effected by operation on the governor adjustment directly; and

Fig. 3 is a schematic fragmentary showing of my invention in which the control is effected by an indirect operation on the governor adjustment.

A regulating device of the first-named type is schematically illustrated in Figure l. A twogear gear-Wheel pump 3, the supply amount of which varies as is known approximately proportional to the rotational speed, is driven from the turbine shaft I through a spur gear drive 2. For the constant outflow cross-section, as, for instance, the fixed opening 6, the supply pressure increases with the rotational speed and, therefore, in proportion to the increased supply of power. This pressure is used for rotational speed regulation. The pump supplies fluid flow through the space 4 in the opening 5 of one of the pump well shafts and through the slot or fixed opening 6 into the open. The governor adjustment may, however, be varied by adjusting the sectional area of opening 6. This is accomplished by rotation of the cam 4'! to act on the sleeve 48. Further, the liquid pressure arrives through the opening '5 of the second pump well shaft in the space 8 and holds the slide bushing 9 against the pressure of the spring ii] in equilibrium. Theslide bushing 9 covers with its piston parts normally, the channels II and I2 so that no oil may penetrate from the external oil conductor l3 into these canals. The oil conductor I3 is fed by the main constant pressure control oil pump 26 of the turbine set which, at the same time is used for the supply of the power means for the movement of the steam admission valve.

If, for example, the rotational speed of the shaft 9 increases on unloading of the turbine, the oil pressure in space 8 increases and displaces the bushing 9 against the spring l0 until a new equilibrium condition is attained between the oil pressure and the spring force. At the same time the pressure 011 is released from the conductor i3 by the entrance of liquid or oil into the canal i i and the oil may penetrate from there through the hole Hi into the space above the piston it. At the same time, the slider bushing 9 opens the exit of the oil from the underside of the piston iii over the canals l5 and 62 into the open. The auxiliary piston It moves downward and takes with it the pulling stick if and with it the wedge or cam [8. This wedge at the same time displaces the system spring plate is, spring iii and bushing 9 opposite to the introduced regulating movement until the canals H and ii are again covered by the bushing ii, and on the occur-- rence of this, the regulating process is brought to rest. The steam admission to the turbine (not shown) is varied by this regulating process through the levers 2i] and 2| and the controi slider the spring 22 operating a rigid member (this only holds for the opening process), because its spring tension is larger than the small resist-- ance in the stick. In the above-described process, the downward movement of the pulling stick i! effects an upward movement of the control slider 22 since the lever 21 at first has its pivot point on the valve spindle 25 as pivot. As the slider 22 is moved upwardly, pressure oil enters from the conductor is in the upper side of the force piston 24 and simultaneousy the oil from the under side of the force piston flows away, so that the steam valve 23 of the turbine closes. The valve comes to rest when the spindle 25 is led through the lever ii of the control slider 22 again to the center position.

On a decrease of the turbine rotational speed by reason of the loading, the above-described regulating process takes place in the reverse sense. The degree of nonuniformity of the regulator is determined by the selection of the hubs and lever lengths, as well as by the inclination of the wedge l 8. The construction and the operation of the regulator in accordance with this description is known.

To limit the maximum permissible moment at any instant, a piston serves which adjusts a stop 32 that cooperates with the lever system 2i in such manner that the opening of the steam admission valve 23 for the turbine is limited by the stop 32. The piston 3i is controlled by the control slider 33 which is set through the levers tit, 35 by a regulating instrument 3% recording the maximum permissible torque. The regulating instrument has two wattmeter systems 3'! and 38 operating opposite to each other which act on a common shaft 39. The system 31 measures the rotational moment transferred from the generator iil to the motor M. This device has a field coil 42 which is connected to a current transformer 63 and is excited in proportion with the stator current. The deflecting coil M is connected through the choke 45 to the potential transformer The potential transferred by the potential transformer is displaced in phase byilO" with reference to the operating current portion of the current. Since the choke coil, if it is very large in comparison to the ohmic impedance of the measuring mechanism, effects a displacement of the current flowing therethrough of 90, the current flowing in the frame is in phase with the work current portion of the machine stator current. The measuring mechanism 37 accordingly produces a torque on shaft 39 proportional to E I cos 0 i which is proportionately equal to the transmitted torque.

The maximum permissible torque is dependent on the exciting current of the machines operating on each other. This value is measured by the wattmeter system 38, the field winding 51 of which is supplied with current proportional to the generator exciting current and the deflecting coil 53 of which is supplied with current proportional to the motor exciting current. Accordingly, by this system a torque is produced on shaft proportional to the product of the generator and motor exciting currents. By comparing the torques opposite to each other of the two

wattmeter systems

38 and 31 with the aid of the common shaft 39, the resulting torque which is present is measured so that, accordingly, the stop it? may, at any time, be so set that the maximum permissible rotational movement is never exceeded.

The electrical regulating instrument which indicates the deviation from the maximum permissible torque may also be permitted to act on the control device in another manner. In Fig. 2, an exemplary embodiment is illustrated in which the instrument 36 influences the outflow cross-section of the gear-wheel and pump 3. The shaft 39 of the instrument in this arrangement displaces a slider 5i which acts to choke off the flow of the control oil into the open. For this purpose the control slider which sets the slot 6 in dependence upon the curve disk 4"! of the rotational speed displacement is here arranged in a chamber 52 to which an oil conductor 53 leading into the open is connected. On the attainment of the maximum permissible rotational moment, the oil conductor it is choked off by the slider 5! so that in this manner an effect on the control of the steam admission in the sense of a limitation is attained. In the embodiment illustrated in Fig. the separate stop 32 illustrated in the Fig. l apparatus and the associated control apparatus Lil, 33 may be omitted.

The regulating instrument which measures the permissible maximum rotational moment may also be permitted to act on the lever which serves for setting the curved disk 4i and an exemplary embodiment of this is schematically indicated in Fig. 3. Here only the slider 48 of the gear wheel pump 3 is illustrated of the device for the control of the driving means supplied to the turbine. The curved disk 4'5 is displaced with the aid of the levers (5i, (i2, 63, B4, 65, 65. Here 64 identifies a control lever which is displaced in correspondence with the desired governor adjustment that is the desired turbine rotational speed, for example, by hand in the direction of the arrow upwardly or downwardly. On this displacement, the lever 63 rotates about the pivot point 61 fixed by the piston 88 and correspondingly displaces the ourved disk 41. The instrument 36 which measures the maximum permissible rotational speed engages at the right hand end of the lever 66 and displaces this lever upwardly or downwardly in accordance with the measured value, the lever 86 also then turning about the point iii. In this displacement of. the lever 55, the control slider 59 is displaced in such a sense that the piston 68 is lifted or dropped. The consequence of this is that the pivot point Ell of the stick is thrust upwardly or downwardly. On the attainment of the maximum permissible rotational moment, this pivot point is so set that the curved disk il is displaced in the sense of a decrease of the rotational speed to the value of the permissible turbine rotational moment.

Obviously, the given limiting device is not limited to the case treated in the example of a Thoma liquid regulator shown, but may of course be used also in other regulator devices, for example, spring regulators.

I am, of course, aware that others, particularly after having had the benefit of the teaching of my invention, may devise still other systems of control falling within the spirit of my invention. I, therefore, wish to be limited only by the scope of. the claims hereto appended and such prior art as may be pertinent.

I claim as my invention:

1. In a ship propulsion system, in combination, a generator, a motor, a turbine for driving the generator, and means, responsive to the ratio of the maximum permissible motor torque to the transmitted torque adapted to control the steam admission to the turbine.

2. In a turbo-electric ship propulsion system, in combination, a turbine, a generator, having field windings, driven by the turbine; a motor, having field windings, coupled to the propeller to drive the propeller and connected to the generator to be supplied with electric energy; and means, responsive to the excitation currents in the field windings of both generator and motor and responsive to the power transmitted from the generator to the motor, adapted to control the fluid admission to the turbine.

3. In a power system the combination of, a prime mover, means for controlling the speed and thus the torque of the prime mover, a generator coupled to the prime mover, a motor connected to the generator, and means, responsive to the ratio of the maximum permissible torque of the motor and the torque transmitted, adapted to control the means for controlling the speed of the prime mover.

4. In a power system the combination of, a prime mover, means for altering the speed of the prime mover, a generator coupled to the prime mover to be driven by the prime mover, a motor electrically connected to the generator, and means, responsive to the ratio of the power transmitted from the generator to the motor to the product of the frequency of. the generator and the field currents of the motor and generator, adapted to modify the operation of the means for altering the speed of the prime mover.

5. In an electric power system, including a generator, a variable speed prime mover for operating the generator, a motor connected to the generator, of means, jointly responsive to voltage of the generator, the armature circuit of the motor, the field currents of the motor and generator, the speed of the generator and the power factor, adapted to alter the operating characteristic of the prime mover.

6. In a power system including a variable speed prime mover, a generator driven by the prime mover, a motor electrically connected to be operated by the generator, means for controlling the speed of the prime mover, and means, jointly responsive to the torque transmitted by the motor and the maximum permissible torque, adapted to alter the operating effect of the means for controlling the speed of the prime mover.

7. In a power system including a variable speed prime mover, a generator driven by the prime mover, a motor electrically connected to be operated by the generator, and means responsive to a predetermined change in the difference between the pull-out torque of the motor and the actual torque transmitted by the motor adapted to alter the speed of the prime mover.

8. In a turbo-electric ship propulsion system, in combination, a turbine, a governor for the turbine adapted to maintain the turbine speed constant, governor adjusting means adapted to select the speed at which the turbine is to operate, a generator driven by the turbine, a motor connected to the generator adapted to drive the ship propeller, means responsive to the pull-out torque of the motor, means responsive to the torque transmitted by the motor, and means responsive to the differential effect of said last two means adapted to change the adjustment of the governor adjusting means.

9. In a turbo-electric ship propulsion system, in combination, a turbine, a governor for the turbine adapted to maintain the turbine speed constant, governor adjusting means adapted to select the speed at which the turbine is to operate, a generator driven by the turbine, a motor connected to the generator adapted to drive the ship propeller, means responsive to the pull-out torque of the motor, means responsive to the torque transmitted by the motor, and means responsive to the difierential efiect of said last two means adapted to jointly with said governor control the speed of the turbine.

10. In a turbo-electric ship propulsion system, in combination, a turbine, a governor for the turbine adapted to maintain the turbine speed constant, governor adjusting means adapted to select the speed at which the turbine is to operate, means for varying the turbine speed in spite'oi' the governor operation, a generator driven by the turbine, a motor connected to the generator adapted to drive the ship propeller, means responsive to the pull-out torque of the motor, means responsive to the torque transmitted by the motor, and means responsive to the diflerential eifect of said last two means adapted to operate said speed varying means.

11. In a turbo-electric ship propulsion system, in combination, a turbine, a governor for the turbine adapted to maintain the turbine speed constant, governor adjusting means adapted to select the speed at which the turbine is to operate, means for varying the turbine speed in spite of the governor operation, a generator driven by the turbine, a motor connected to the generator adapted to drive the ship propeller, means responsive to the pull-out torque of the motor, means responsive to the torque transmitted by the motor and means responsive to the diiferential effect of said last two means adapted to control the operation of the speed varying means whereby the governor and speed varying means jointly alter the speed of the turbine.

12. In a ship propulsion system, in combination, an engine, means for varying the speed of the engine, a generator coupled to the engine, a motor coupled to the propeller, means responsive to the torque transmitted by the motor, means responsive to the pull-out torque of the motor, and means responsive to the differential effect of said last two means adapted to vary the speed of said engine.

THEODOR DEEG.