US2514930A - Speed regulator for hydraulic turbines - Google Patents

Description

July 11, 1950 J. H. BRANHAM 514,930

SPEED REGULATOR FOR HYDRAULIC TURBINES Filed Deo. 27. 1946 Patented July l 1,Y 1950 UNITED STATES PATENT OFFICE SPEED REGULATOR FOR. HYDRAULIC TURBINES James H. Branham, Rockford, Ill., assigner to Woodward Governor Company, Rockford, Ill., a corporation of Illinois Application December 27, 1946, Serial No. 718,533

3 Claims.

ylhis invention relates to governor controlled regulators such as are used for controlling the speed of water turbines for driving electric generators. To prevent hunting under changing load (Cl. Zim- 4.0)

2 of such governors is also hydraulically operated and, as shown, includes a huid filled chamber i9 communicating with a cylinder 2t in which slides a transmitting piston 2l urged inwardly by conditions, the governor of such a regulator in- 5 a spring 22 and moved outwardly through a cable Corporates a so-called compensating mechanism. 3 and linkage 24 in accordance with changing When constructed to provide proper speed control positions of the servo piston vI l. A piston 25 for during idling operation of the turbine, the comreceiving the compensating force slides in a cylinpensating mechanism limits to an objectionable der 25 and applies the vcompensating force degree the speed at which the wicket gates may 10 through a lever 2l to the pilot valve stem Il'. In be moved when the generator load is imposed on response to each movement of the piston 2|, a the turbine. f spring 23 is either tensioned or compressed, and The primary object of the present invention thereafter acts to center the piston 25 as permitis to modify the action of the governor compented by leakage into or out of the chamber I9 eating mechanism automatically in accordance l5 through a needle valve 2li. The restoring force with the changing turbine loads, whereby to adapt initially applied to the pilot valve to produce temthe governor for eicient regulation of the turbine porary speed droop is thus dissipated gradually speed under all conditions. by such leakage, as the turbine speed, following A more detailed object is to provide a compena load change, is brought back to the isochronous sating type turbine governor in which the com- 20 value. pensating eiect is reduced a predetermined The magnitude of the compensating force apamount in response to loading of the turbine by plied to the control valve may be increased or the generator, and is correspondingly increased decreased as desired by closing or opening the by unloading of the turbine, provided that the needle valve 29. Ordinarily the latter is set to turbine gates 21T@ DOSiOIled fOI 11G-10361 ODQIa- 25 provide a substantial amount oi compensation in tion.

The invention also resides in the novel structure of the mechanism used in carrying out the foregoing objects.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure l is a schematic view of a turbine speed regulator embodying the novel features of the present invention.

Fig. 2 is an enlarged vertical cross sectional view oi the governor compensating mechanism.

For purposes of illustration, the invention is shown in the drawings incorporated in a hydraulic governor for controlling the flow of fluid to a servo actuator such as a cylinder I0 and a piston II operating through the usual rod I2 to shift a ring I3 which is connected through arms lll with wicket gates I5 of the hydraulic turbine. The latter drives an electric generator 8 which is rendered operative by closure of the usual remotely controlled power actuated breaker switches indicated generally at S.

The governor includes flyballs le driven by the turbine and operating the stem I 1 of a pilot valve which, together with a relay Valve and associated mechanism indicated at I8, controls the iiow of pressure fluid to and from the servo cylinder I0. The so-called compensating mechanism order to enable the turbine speed to be regulated properly when the turbine is being started or idling with the generator switches 9 open, the flywheel eilect then being comparatively low. However. when the generator has been rendered operative and the iiywheel eect of the system increased correspondingly, such a high compensating efiect slows down to an objectionable degree the rate at which the gates may be moved under the control of the governor.

In accordance with the present invention, provision is made for reducing the compensating eiect automatically, and preferably by a predetermined amount when the generator is rendered operative and then, after the generator has been disabled, increasing the compensating effect to its full original value only after the gates I5 have become substantially closed. In this Way the effect of the compensating mechanism in restricting the gate movement is minimized so that the gates may be moved rapidly whenever the turbine is loaded or when the gates are being closed after disabling the generator.

Such automatic modication of the compensating mechanism is accomplished in the present instance through use of an auxiliary uid valve 3l which is normally closed by a spring 32 and which, when opened, permits fluid to by-pass the main needle valve 23, the resultant effect being to enlarge the leak restriction in the compensating mechanism.

Preferably the valve 3l is controlled electrically so that it may respond to the desired combination of operating conditions. To this end the valve is of the needle type, with its stem 33 co-nnected to the armature 34 of a solenoid 35 by which the valve may be opened against the action of the spring 32. To enable the flow of fluid through the by-passage 38 to be adjusted, a needle valve 39 is arrangedv in the other end of the passage for adjustment by manual turning of a knob 3l. To open the by-passage 38 automatically when the generator 8 is rendered operative, an energizing circuit 39 for the solenoid 35 is eX- tended through a switch 4!) which is closed and opened simultaneously with the switches 9 by which the generator is thrown intov and out of operation. Thus, during starting ofthe turbine, when a substantial amount of compensation in the governor is required, the by-passage 38 is closed and the needle Valve 29 alone determines the compensating effect. The latter is reduced, however, as soon as the flywheel effect of the generator is applied to the system, thereby permitting the gates to be operated at the desired rate.

Reclosure of the by-passage 38 by deenergizing the solenoid 35 is dependent upon a combination of two conditions; that is, cutting the generator out of operation together withr the approach of the gates I to the highest no-load position likely to be encountered in service. Accordingly, a parallel energizing circuit 4| for the solenoid is extended through a switch 42 which is operated by a cam 43 movable in unison with the gates l5, for example'as by being carried bythe servo piston rod l2. As a result, the solenoid is not deenergized to close the by-passage 3S when the generator is disabled with the gates open a substantial distance. Instead, the by-passage remains open to leave the governor conditioned for rapid closure of the gates to the no-load position, whereupon the switch 42 is opened to increase the compensating eiiect of the governor as required for idle operation of the turbine.

I claim as my invention:

1. For use with a gate controlled turbine for driving an electric generator, the combination of a servo actuator having a member movable back and forth to open and close the turbine gates, a governor controlling said actuator in response to the turbine speed and having mechanism for producing compensation, means by which said compensation may be decreased a predetermined amount, means for maintaining said last mentioned means disabled during idling of said turbine and for actuating the same to decrease the compensation of said governor when said generator is rendered operative, and means for disabling said compensation reducing means when the generator is renderedinoperative and said servo member has been returned to a no-load position.

2. For use with a hydraulic turbine for driving an electric generator, the combination of, a speed regulator for the turbine including a governor having automatically acting compensating mechanism, means for decreasing the compensating eiect of said mechanism automatically as an incident to imposition or" the generator load on the turbine, and means for increasing the compensating effect of said mechanism automatically in response to return of said regulator to noload position after disabling of the generator.

3. For use with a hydraulic turbine for driving an electric generator, the combination ci, a speed regulator for the turbine including a governor having automatically acting compensating mechanism, means by which the compensating effect of such mechanism may be changed, a device responsive to changes in the loading of said turbine, and means operable by said device when the load of said generator is imposed on said turbine to actuate said last mentioned means in a direction to decrease the eiect of said compensating mechanism.

JAMES H. BRANI-EAM.

REFERENCES CETED The following references are of record in the iile of this patent:

UNITED STATES PATElQITS Number Name Date Re. 17,161 Innes Dec. 11, 1928 245,591 Westinghouse, Jr. Aug. 9, 1881 846,897 Benjamin Mar. 12, 1907 1,106,434 Woodward Aug. 11, 1914 1,584,602 Bradshaw et al. May 11, 1926 2,039,507 Woodward May 5, 1936 2,228,153 Pfau Jan. 7, 1941 2,404,968 Leyer July 30, 1945

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