GB2194358A

GB2194358A - Steam turbine control

Info

Publication number: GB2194358A
Application number: GB08716839A
Authority: GB
Inventors: Frantisek Pokorny; Zdenek Bures; Josef Dobias
Original assignee: Skoda kp
Current assignee: Skoda kp
Priority date: 1986-07-17
Filing date: 1987-07-16
Publication date: 1988-03-02
Anticipated expiration: 2007-07-16
Also published as: CS263629B1; DE3723176C2; GB2194358B; CN87105470A; CS544886A1; CH674053A5; FR2605046B1; DE3723176A1; CN1023142C; GB8716839D0; FR2605046A1

Description

GB2194358A 1 SPECIFICATION method comprises a set of regulators, sets of

circuits of introduced values of openings of HP Method for the regulation of a steam tur- and LP valves, a set of electrohydraulic con bine and arrangement for carrying out the verters, a summing element and a set of cir method 70 cuits for manual and automatic control. Ac cording to this invention the valves of the The.invention relates to a method of elecsteam turbine driving the delivery pump are tronic regulation of a steam turbine driving a actuated independently and directly in depen delivery pump and to an arrangement for car- dence on the kind of operation of the main rying out the method. 75 steam turbine. According to a further de velop- The amount of water supplied by a delivery ment a second electrohydraulic converter is pump to the feeding system of a steam genconnected to the control elements of the LP erator is regulated by the variation of the valves and a first electrohydrau lid converter of number of revolutions of the steam turbine. the control circuit is connected to control ele driving the delivery pump. The regulation of 80 ments of the HP valves, one input of said the number of revolutions of the steam turbine circuit is connected to the circuit of the intro driving the delivery pump is accomplished by duced value of opening of HP valves, another its regulation valves. The turbine driving the of its inputs is connected to the circuit of the delivery pump comprises two kinds of regula- introduced value of LP valves, a still other in tion valves: main low pressure valves, or LP 85 put is connected to a pick-up device of revo valves, and substitution high pressure valves lutions and its two remaining inlets are con or HP valves. Each kind of said valve is assonected to a first and second output of a cir ciated with a steam of different quality. The cuit for separation of the signal. The input of HP valves are with live steam entering the the circuit for separation of the 'signal is high pressure part of the main steam turbine 90 thereby connected to the output of'the regula and the LP valves with steam which has al- tor of revolutiong, its first input is connected ready lost a part of its power due to passage to the output of the circuit of the introduced through the high pressure part of the main number of revolutions, whereas its second in steam turbine. From that follows that the HP put is also connected to a pick-up device of valves are used when the main turbine is at 95 the number of revolutions. A circuit for manual standstill or is used to generate only little control of the introduced number of revolu electric power. After the main turbine has fully tions and a circuit for automatic control of the started, the LP valves start their operation in number of revolutions are connected to inputs dependence on increasing amounts of steam of a circuit of the introduced number of revo which has already passed a part of the high 100 lutions, the circuit for automatic control of the pressure part of the main steam turbine. introduced number of revolutions is connected Up to now the extent of opening of both with a regulator of feeding and with a regula- HP and LP valves of the turbine driving deliv- tor of warming, the latter being connected ery pumps has been determined by the pres- with a pick-up device of the temperature of sure of oil controlling said valves which oil is 105 the metal of the turbine. The first input of a supplied as a signal from a hydraulic regulator first change-over switch of the control circuit of revolutions so that in case of an increasing is connected to the oulput of the circuit of the pressure of this oil first the LP valves are introduced value of the opening of HP valves, opened and after their full opening, the openthe outputs of which are connected both to ing of HP valves of the turbine driving the 110 the circuit for manual introduction of the.posi delivery pump is accomplished. This intercon- tion of HP valves and also to the circuit for nection does not change in the course of op- automatic introduction of the positioin of HP eration, which causes a number of difficulties valves, whereas the second input of the sec particularly in the course of passage from one ond change-over switch of the control circuit kind of valve to another one and also does 115 is connected to the output of the circuit of the not enable earlier opening of HP valves, until introduced value of opening of LP valves, the the LP valves are fully opened. The require- inputs of which are connected both to the ment of accurate regulation of revolutions of circuit for manual introduction of the position the turbine within a wide range is rather diffi- of LP valves and also to the circuit for auto cult to solve for a hydraulic regulator and the 120 matic introduction of the position of LP valves.

requirement of an automatic warming of both The second input of the circuit for automatic the turbine proper and of the pump after procontrol of the introduced number of revolu longed standstill is practically impossible to tions is connected with the output of the re solve. gulator of feeding.

It is an object of this invention to reduce 125 The main feature of the invention consists in substantially the above-mentioned drawbacks that the control circuit comprising change-over by utilising the dependence of opening of HP switches, minimum selectors, electrohydraulic and LP valves of the turbine driving the deliv- converters and overtravel regulators has inputs ery pump on the number of revolutions of the of electrohydraulic converters connected to turbine. An arrangement for carrying out this 130 outputs of minimum selectors, one of their 2 GB2194358A 2 inputs being always connected with the output gulation of revolutions with manual introduc of a change-over switch and their second in- tion of the number of revolutions, operation put is connected to the output of an overtrawith regulation of revolutions with automatic vel regulator. The input of the overtravel regu- introduction of the number of revolutions by lator is thereby connected with the input of a 70 the output signal from a superposed feeding summin 9 element and the first input of the regulator, operation with a regulation of revo first change-over switch is.connected to the lutions with automatic introduction of the in output of the circuit of the introduced value of troduced number of revolutions by the output opening of HP valves, whereas the first input signal from the regulator of warming in case of the second change-over switch is con- 75 of starting after a prolonged standstill and nected to the output of the circuit of the in- safeguarding of the aggregate in case of some troduced value of opening of LP valves. The failure causing an increase or an inclination for second input of the first change-over switch is increase of revolutions of the overtravel regu thereafter connected with the first output of lator.

the circuit for separation of the signal and the 80 A practical embodiment of an arrangement second input of the second change-over for regulation of a turbine according to this switch is connected with the second output of invention will now be described, by way of said circuit for separation of the signal. example, with reference to the accompanying An advantage of the method for regulation diagrammatic drawing representing a bloc wir- of a turbine and of the arrangement for execu- 85 ing diagram.

tion of this method is the independent direct According to said embodiment the main ele- control both of the HP and LP regulation ment of the arrangement for regulation of the valves. The acting medium of said valves is turbine is a regulator 1 of revolutions. The again oil, in the case given each of said valves output 113 of a summing element 11 is con has its own circuit. Thus practically any arbi- 90 nected to the input 101 of the regulator 1 of trary combination of their mutual opening and revolutions. The output 123 of a circuit 12 of thus their adjustment to operating conditions the introduced number of revolutions is con of the turbine is enabled. The electronic regu- nected to a first input 111 of the element 11.

lator of revolutions is accomplished as an The output signal from an electronic pick-up adaptive regulator which changes its para- 95 device PR of revolutions is connected to a meters whether it cooperates with HP or LP second input 112 of said element 11. The regulating valves. This method thus secures a output 143 of a circuit 14 for automatic con high constant accuracy of regulation of revolu- trol of the introduced number of revolutions is tions within their whole range and enables connected to the first input 121 of the circuit also to solve problems of automatic warming 100 12 while the output 131 of a circuit 13 for in the course of starting after standstills of manual control of the introduced number of different length. revolutions is connected to the second input The method and the arrangement according 122 of the circuit 12. The output 502 of a to this invention enables the following alterna- regulator 5 of warming up is connected to a tives of Operation of a turbine driving a deliv- 105 first input 141 of the circuit 14, while the ery pump: primarily pn operation using a regu- output signal 810 from a superposed feeding lation of revolutions 'by control of HP and LP regulator 8 is connected to a second input valves by an output signal from the circuit for 142 of the circuit 14. To the input 501 of the separation of the signal, the mutual interconregulator 5 a pick-up device PT of the temper nection of HP and LP valves being adjustable 110 ature of a critical place of the turbine is con in the distributor according to the kind oper- nected.

ation; it enables furthermore an operation of The output 102 of the regulator 1 of revolu- the turbine by regulation of revolutions by tions is connected to the input 151 of a cir control of HP valves by an output signal from cuit 15 for separation of the signal from the the circuit for separation of the signal and of 115 regulator 1 of revolutions. A first output 152 LP valves from the circuit of the introduced of the circuit 15 for separation of the signal i value of opening of LP valves; furthermore connected to a second input 232 of the first ( also an operation of the turbine by regulation change-over switch 23, the output 203 of a of revolutions by control of LP valves by an circuit 2 of the introduced value of opening of output signal and in addition an operation of 120 HP valves being connected to its first input the turbine by regulation of the revolutions by 231. The output 211 of a circuit 21 for man control of LP valves by an output signal from ual introduction of the position of HP valves is the circuit for separation of the signal and of connected to a first input 201 of the circuit 2.

HP valves from the circuit of the introduced The output 221 of a circuit 22 for automatic value of opening of HP valves; in addition they 125 introduction of the position of HP valves is enable control of the position of HP valves connected to a second input 202 of the cir from the circuit of the introduced opening of cuit 2.

HP valves and LP valves from the circuit of The output 233 of the first change-over the introduced value of opening of LP valves; switch 23 is connected to a first input 411 of they enable furthermore an operation with re- 130 a first minimum selector 41, to the second 3 GB2194358A 3 input 412 of which the output 402 of an when starting.

overtravel regulator 4 is connected. The out

Claims

put 413 of the first minimum selector 41 is CLAIMS connected to the input

601 of an electrohy- 1. Method for the regulation of a steam draulic converter 6 for HP valves. 70 turbine, utilising the dependence of the degree The second output 153 of the circuit 15 for of opening of high pressure and low pressure separation of the signal is connected to the valves of the turbine driving a delivery pump first input 331 of a second change-over on the number of its revolutions, wherein the switch 33, the output 303 of the circuit 3 for valves of the steam turbine driving the deliv control of the position of LP valves being con- 75 ery pump are adjusted independently and di nected to its second input 332. the output rectly in dependence on the kind of operation 311 of the circuit 31 for manual introduction of the main steam turbine.

of the position of LP valves is connected to
2. Arrangement for the regulation of a the first input 301 of the circuit 3 of the steam turbine comprising a control circuit (01), introduced value of opening of LP valves and 80 wherein a first electrohydraulic converter (6) of the output 321 of the circuit 32 for automatic the control circuit (01) is connected to control introduction of the position of LP valves is elements of high pressure valves and a sec connected to its second input 302. ond electrohydraulic converter (7) of a control The output 333 of the second change-over circuit (01) is connected to control elements switch 33 is connected to a first input 421 of 85 of low pressure valves and wherein one input a second minimum selector 42, to the second of said control circuit (01) is connected to a input 422 of which the output 402 of the circuit (2) of the introduced value of opening overtravel regulator 4 is connected. The out- of high pressure valves, one input is con put 423 of the second minimum selector 42 nected to a circuit (3) of the introduced value is connected to the input 701 of an electrohy- 90 of opening of low pressure valves, one input draulic converter 7 for LP valves. is connected to a pick-up device of revolu- One of the main features of operation of the tions and further inputs are connected to a arrangement for regulation of a turbine accord- first and a second output (152, 153) of a ing to this invention is the separation of the circuit (15) for separation of the signal, the control of the position of HP and LP valves to 95 input (151) of which is connected to the out two independent parts. The position of HP put (102) of a regulator (1) of revolutions and valves is determined by the output signal from the input (101) of the regulator (1) of revoluti a first electrohydraulic converter 6 and the po- ions is connected with the output (113) of a sition of. LP valves is determined by the out- summing element (11), a first input (111) of put signal from a second electrohydrautic con- 100 which is connected to the output (123) of a verter 7. Each of said converters 6, 7 is in circuit (12) of the introduced number of revo principle controlled in three ways: by the outlutions, whereas its second input (112) is also put signal from circuits 2, 3 of the introduced connected with the pick- up device of revolu value of opening of valves, or by the output tions, while to inputs (121, 122) of the circuit signal from the regulator 1 of revolutions or 105 (12) of the introduced number of revolutions a finally by the output signal of an overtravel circuit (13) for manual control of the intro regulator 4 in dependence on conditions of duced number of revolutions and a circuit (14) operation and on needs of the attendant. for automatic control of the introduced number The circuits 2, 3 of the introduced value of of revolutions are connected, the latter being opening of valves can be controlled either 110 connected to a feeding regulator (8) and to a manually or automatically, the automatic con- regulator (5) of warming, the output (502) of trol of the position of the respective regulation which is connected with a pick-up device of valves is used in case of a change-over from the temperature of metal of the turbine and control of the position to the regulator of also a first input (231) of a first change-over revolutions in order to safeguard this change- 115 switch (23) of the control circuit (01) is con over without shocks. The introduced number nected to the output (203) of the circuit (2) of of revolutions can also be changed manually the introduced value of opening of high pres or automatically. The arrangement for regula- sure valves, the inputs (201, 202) of which tion of the turbine enables both the valves to are connected both to a circuit (21) for man be operated in series by.signals from the re- 120 ual introduction of the position of high pres gulator 1 of revolutions, it also enables any of sure valves and also to a circuit (22) for auto said valves to be changed over to manual matic introduction of the position of high pres control while the other valve is controlled by sure valves, whereas the second input (332) the regulator 1 of revolutions. If the intro- of a second change-over switch (33) of the duced number of revolutions is at conditions 125 control circuit (3) of the introduced value of 11 automatic-, it is changed either by the outopening of low pressure valves is connected put signal from the feeding regulator 8 or by to the output (303) of the circuit of the intro the output signal from the regulator 5 of duced value of opening of low pressure warming. The regulator 5 of warming ensures valves, the inputs (301, 302) of which are that the allowed heat stress is not surpassed 130 connected both to a circuit (32) for automatic 4 GB2194358A 4 introduction of the position of low pressure valves and whereby the second input (142) of the circuit (14) for automatic control of the introduced number of revolutions is connected with the output (801) of a feeding regulator (8).
3. Arrangement according to Claim 2, wherein the inputs (601, 701) of electrohy draulic converters (6, 7) are connected to out puts (413, 423) of minimum selectors (41, 42), always one of their first inputs (411, 42 1) of said minimum selectors (41, 42) is connected with one output (23.3, 332) of change-over switches (23, 33) and their sec- r.

ond input (412, 422) is connected to the out put (402) of an overtravel regulator (4), the input (401) of which is connected with the second input (112) of the summing element (11) and the first input (231) of the first change-over switch (23) is connected to the output (203) of the circuit (2) of the intro duced value of opening of high pressure valves, whereas the first input (331) of the second change-over switch (33) is connected to the output (303) of the circuit (3) of the introduced value of opening of low pressure valves and the second input (232) of the first change-over switch (23) is connected with the first output (152) of the circuit (15) for separ ation of the signal and the second input (332) of the second change-over switch (33) is con nected with the second output (153) of said circuit (15) for separation of the signal.
4. Method for the regulation of a steam turbine substantially as herein described with reference to the accompanying drawing.
5. Arrangement for the regulation of a steam turbine constructed, arranged and adapted to operate substantially as herein de scribed with reference to, and as shown in, the accompanying drawing.

Published 1988 atThe Patent Office, State House, 66/71 High Holborn, London WC I R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD.

Printed by Burgess & Son (Abingdon) Ltd. Can. 1/87.