FR2486144A1 - ADJUSTMENT AND PROTECTION SYSTEM FOR TURBINES - Google Patents

Abstract

THE TURBINE REGULATION AND PROTECTION SYSTEM INCLUDES ONE OR MORE REGULATION VALVES 3 AND A SNAP-CLOSING VALVE FITTED IN THE WORKING FLUID SUPPLY DUCT 2 OF THE TURBINE 1, ROTATION SPEED MEASURING PROBES 9 , 9 AND AN ADJUSTMENT AND PROTECTION DEVICE 11 CONTROLLING THE VALVES 3, FOR THE ADJUSTMENT SYSTEM 3, on the one hand, AND FOR THE PROTECTION SYSTEM, on the other hand, PROVIDED FOR TWO SPEED REGULATORS 11 IDENTICAL BUT INDEPENDENT ONE OF THE OTHER AND OF WHICH ONE IS IN DYNAMIC CONNECTION WITH THE ADJUSTING VALVE (S) 3 WHILE THE OTHER IS IN DYNAMIC CONNECTION WITH THE INSTANT-CLOSING VALVE, WITH EACH REGULATOR 11 BEING ASSOCIATED WITH TWO SPEED SENSORS OF EFFECTIVE ROTATION 9, 9 WHICH ARE INDEPENDENT OF ONE OF THE OTHER.

Description

The present invention relates to an adjustment and protection system

for turbines with one or more

  several regulating valves and a shut-off valve

  instantaneous measurement provided in the supply pipe of the turbine with working fluid, tachometric probes

  to which is connected an adjustment and protection device

  tion controlling the distributors or valves.

  Up to now, it has been customary to adjust the turbines, including the emergency control, by means of mechanical-hydraulic systems. During normal operation, a speed regulator is then provided which actuates the distributors mechanically and hydraulically.

  control. To protect the turbine from over-

  a quick-closing device is provided, which consists essentially of a finger housed in the shaft of the turbine and which, when a certain speed is exceeded, actuates, preferably under the effect of force centrifugal, a ratchet releasing, via an inversion mechanism, the liquid

  hydraulic for controlling inset valves

  tantane. An electromagnetic valve is also provided in the hydraulic fluid supply circuit in order to allow an electrical emergency release, for example, by a generator protection device,

  emergency stop buttons or similar devices

logues.

  This embodiment has a certain name-

  bre of disadvantages. The mechanical parts are, for example-

  full, relatively sensitive and fragile and the function-

  cannot be damaged due to accumulation of dirt, oil resinification, aging

and the fatigue of matter.

  Verification of the proper functioning of these provisions

  Known sitives is also difficult. This verification is carried out either by artificially creating an overspeed by interrupting the operation of the turbine or by simulating an overspeed by suppressing the emergency trip during the operation of the turbine. During this simulation, actual values are measured or the trip due to overspeed is checked by pumping oil under the commanding finger

  instant closing of the valve.

  The command for normal service and the safety command are different with regard to their

  conception and their way of operating which presents the

  agrees that neither of the two commands can perform the function of the other in the event of failure of one of the

devices.

  The cost price of these devices is also high because as a safety measure we are led

frequently to double them.

  It is also known to order a trip device.

  quick stop due to overspeed per track

  electronic-hydraulic. In this case the speed of rota--

  tion of the turbine is measured inductively and sur-

  monitored by an electronic evaluation device, the

  triggering the instant stop is generally com-

  controlled by an electromagnetic valve. In order to be able to check the device during normal operation, it is necessary to protect the turbine from switching

  and put into operation a parallel surveillance system

  lele and put into service at the same time a control circuit. This control circuit has the disadvantage

  to interrupt the trip circuit and a trip

  Safe during operation of the turbine can only be obtained after switching the control circuit back to its normal state which is not

always verifiable.

  Electronic control systems are also known.

  tronic-hydraulic; however these systems are not linked to the protection systems and they act

  only on regulating valves.

  The object of the present invention is to create an adjustment and protection system which is composed from the raising of the effective value up to

  control elements, of identical but independent assemblies

  each other and which offers the possibility of a complete verification of all the functions and this both at standstill and during operation without however harming the latter. The use of identical sets must make it possible to maintain, under certain

  conditions, a rescue service during a failure-

  launches of a circuit or a set of the fact that safety can be ensured without limitation by another circuit. We

  thus obtains high availability (reduction of pro-

  failure babblings) and it is obvious that this system

  must allow adjustment and safety to be ensured

  facts as well as the realization of redundancy systems while offering the possibility of adaptation to others

  regulation and control systems.

  The above problems are solved in accordance with the invention by a system of the type mentioned above and which is characterized in that, on the one hand,

  for the adjustment system and, on the other hand, for the system

  protective tem two substantially identical but independent speed regulators, one of which is in active connection with the regulating valve (s) while the other is in active connection with the instantaneous closing valve and in that two independent devices for measuring the effective speed of rotation

  are associated with each of the regulators.

  The advantage of this embodiment which pre-

  sees, in accordance with the invention, identical systems

  for the adjusting device and the protection device

  tion, lies in the fact that one of the regulators can temporarily take over the function of the other, for example, when a regulator fails. Therefore it is no longer necessary to provide duplicate devices even when the security requirements are the

more severe.

  Various other features of the invention

  moreover emerge from the detailed description which follows.

  Embodiments of the subject of the invention are shown, by way of nonlimiting examples, in

attached drawings.

  Fig. 1 schematically represents a single circuit

cooked turbine setting.

  Fig. 2 is the diagram of a circuit making it possible to check an instantaneous closing valve during the

turbine operation.

  Fig. 3 is the block diagram of a system

  before the invention comprising a cruise control and

  regulators for quick stop and start-up.

  In fig. 1 the turbine bears the reference 1. In the duct 2 supplying the turbine 1 with working fluid,

  for example steam, is (are) mounted the (s)

  adjusting valve (s) 3 which is (are) actuated by a control 6 connected to an adjusting oil pipe 4 and a hydraulic fluid pipe 5. The shaft 7 of the

  turbine 1 carries a disc 8 which has on its circumference

rence of grooves or teeth.

  Two induction measurement probes 9, 9 'which provide

  at each passage of a tooth, an electrical impulse to a regulator 11, via conductors 10, ', are associated with the disc 8. A control current, for example a direct current covering a plate from 0 to about 20 mA and coming from a control regulator (cascade regulator or similar device) can be

applied to regulator 11.

  Thanks to the conductor 13 it is possible to apply an external signal to the regulator 11, that is to say that

  instant stop can also be triggered from the ex-

  such as manually or from a device

  generator protection positive.

  The regulator device 11, intended for adjusting the nominal value, is designated by 14; the keys 16, 17, connected to the regulator II by the conductors 18 and 19, are used for remote adjustment of the nominal value of the speed of rotation. The three conductors 20, 21 and 22 connect the regulator II to indicating devices 23, 24, 25 which display the momentary speed of rotation of the turbine, the nominal value set and the magnitude of the

  regulator output signal. Outputs 26 to 29 con-

  dual towards locking and signaling and trans-

  set the signals for the stop n = 0, the minimum speed nmin 'the maximum speed nmax and signal an instantaneous stop n ,, * The conductor 30 conducting the output signal from the regulator 11 connects the latter to a member adjustment

  pressure 31 which acts as an electrical converter

  tronic-hydraulic and from which the liquid conduit starts

setting 4 already mentioned.

  The speed of rotation is measured by two magnetic induction probes 9, 9 '. The regulator 11 always chooses the most important signal among the signals

  delivered by the probes. The machine can therefore

  keep operating without disturbance even if one of the measurement channels fails (for example

  cut of one of the conductors 10, 10 '). For this reason

  his we chose generators and quilors

  a disturbance or failure may

  see only lower frequency signals.

  The regulator output signal is applied

  as a current between 0 and 20 mA at the

  pressure regulating valve 31 which converts the electrical signal into an oil pressure pulse which acts

  directly on the control elements in the pre-

  feels the control 6, of the adjustment distributor (s) 3.

  As a pressure regulator

  As an electro-hydraulic converter, you can

  preferably use the electromagnet & plon core

  geur described by patent AT 306,171.

  The oil pressure controlled by the adjusting member 31 is applied as a control variable

  directly to the adjustment devices (command 6).

  An instantaneous stop device is inserted in the adjustment system. This instantaneous stop device causes, through the

  pressure 31 and by removing the auxiliary energy, the ar-

  instant shutdown of the turbine as soon as one of the two measuring channels of the actual value 10 or 10 'signals a

  overspeed or when the two effective values present

  attempt an unacceptable change in time or when an effective value channel is missing and the second effective value is subject to a temporary change

  inadmissible. It is also possible to order the ar-

  instant shutdown from the outside via the con-

conductor 13.

  Thanks to the use of a dynamically controlled electromagnet for the 3Ihon pressure regulating member, it is possible to create the necessary control forces without providing for servo systems. As a result, the response time can be reduced considerably and the often narrow sections of the pre-order systems no longer exist and the danger of fouling resulting therefrom

is deleted.

  The adjustment system includes an instantaneous shutdown system that can be checked during operation of the turbine. The block diagram in fig. 2 shows a system of this type. A control circuit 32, 32 'is connected directly to each of the conductors 10, 10' coming from the two probes 9, 9 '. Each control circuit includes a generator 33, 33 'capable of supplying a train

of pulses.

  The frequency of the pulse trains delivered by the generators 33, 33 ′ is a function of the magnitude of the direct voltage which, coming from a voltage selector 35 equipped with a switch 36, is applied to the

  pulse generators 33, 33 'via -

  conductors 34, 34 '. When the DC voltage has a maximum value, the generators deliver pulse trains of a frequency also maximum. This frequency corresponds to the highest rotational speed that can be processed and which is greater than the rotational speed at which the turbine must stop quickly. The selector switch 36 does not make it possible to connect,

  each time, that one of the conductors 34, 34 '. The interior

  generator (voltage selector 35) can only deliver a DC voltage if the blocking element (for example an AND element with no function), at whose two inputs

  are connected a trip circuit 38 and a

  mutator (control switch 39), outputs a signal

  corresponding to the integrator (voltage selector 35).

  The signal emitted by that of the pulse generators

  sions 33 or 33 ', controlled by the DC voltage, is superimposed on the signal created by the probes 9 and 9'. There is no inversion of the transmitter on "probe?

or "generator".

  The two conductors 10, 10 'are connected to

  measurement converters 40, 40 'which provide a voltage

  continuous and dependent on the frequency of the trains of im

  pulses on the limit value stages 41, 41 '. The outputs of the two limit value stages 41, 41 'trigger, by

  through the elements OR 42 and 43, the instant stop

  tane of the turbine by removing the excitation of relay 48. The instantaneous shutdown can also be controlled by an external signal (conductor 13) or by a system of

  surveillance 45. The proper functioning of the sur-

  monitoring can also be checked using the key

  control 47 and the blocking element 46 AND. -

  For checking the excitation of relay 48

  commanding the instantaneous stop is deleted when the

  appearance of the trigger signal (output of limit value stages 41, 41 'or output of the monitoring system). As a result, the pressure adjusting member 31 no longer receives auxiliary energy and the blocking conductor 38 is supplied with 24 volts. This causes the blocking of the ET elements 46 and 37 and the verification is complete. Relay 48 then returns to its initial position. The output of the comparator circuit 43 is connected to a relay 48 controlling the instantaneous stop and to a relay

  49 which is only used for warning and indication

  cation. Auxiliary energy, for example a direct voltage of 24 volts, is applied to the pressure regulating member 31 via the stop relay

snapshot 48.

  When the relay 48 is switched to the position shown in fig. 2, the DC voltage is cut off

  and the valves 3 close (instantaneous closing).

  As shown in fig. 2, both

  speed measurement channels has a monitoring circuit

  launches speed which, when a set limit value is reached, cuts off the auxiliary energy of the pressure regulator via a relay. As a result, the magnet is no longer excited and the pressure of the pulsed oil falls. Steam control valves

  close and the turbine is stopped. Relay 49, branch

  checked in parallel, is available for external control.

  The instant closing system is the most important protection system in a turbine installation. For this reason it is necessary to check the components of this system at regular intervals. The described adjustment system allows active control of all the elements in each service phase without exerting any influence on the speed of rotation of the turbine. For this purpose it is possible to simulate, using each of the measuring probes, a "control speed" with progressive increase. During verification, the second measurement channel is then responsible for the adjustment alone. The protection system reacts

  as soon as the speed of rotation requires instant stop -

  of the turbine is reached. The relay controlling the stop is then switched, that is to say that it is no longer energized, and it cuts the auxiliary energy of the pressure adjusting member. The closing contact of relay 48 signals the triggering of the instantaneous stop. Then the control rotation speed is reduced to zero, the relay 48 is energized again and the pressure adjusting member

resumes its function.

  The excitation of relay 48 is not removed until

  maximum for 20 milliseconds which corresponds to

  bleed to a setting cycle of the magnetic circuit of the pressure setting member 51. This results in the position of the steam setting valves not being

not changed.

  The correct operation of the adjustment valves can be easily checked by slightly modifying the value

nominal speed.

  Very high security and perfect reliability are obtained by virtue of the fact that the instantaneous closing valve

  is also equipped with a cruise control.

  All functional units (regulator, or-

  pressure adjustment valve, adjustment controls) are designed so that the installation stops ("fail-safee" behavior) as soon as the auxiliary energy

  (electric, hydraulic) is missing.

  Fig. 3 schematically represents an installation

according to the invention.

  Turbine 1, its shaft 7 and the transmitting disc

  8 are shown in the same way as in FIG. 1.

  A working machine 50 (in particular a generator or a compressor) is driven by the turbine. In the working fluid supply duct 2 of the turbine

  are successively fitted with a shut-off valve

  tantanum 51 and one or more regulating valves 52.

  These two valves are actuated by control mechanisms 53, 54 which are connected, on the one hand, together or parallel to a source of hydraulic liquid via the conduits 55, a coupling valve 56, a conduit 57 and an emergency stop valve 58 which can be controlled manually, and, on the other hand, to a pressure adjustment member 31 and 31 'by a hydraulic control conduit 60, 61. In the case of 'a stop

  instantaneous the coupling valve directs the hydraulic liquid

  link to valve control mechanisms 53 and 54.

  The system shown in fig. 3 comprises two completely identical regulators, namely the regulator

  instantaneous stop 62 and cruise control 63.

  Each of these two regulators is connected by two conduc-

  ters 10, 10 'each time two probes 9, 9'. An inter-

  emergency switch 65, a locking device 66 and an external control 67 are connected to the two regulators 62, 63 by means of an intermediate circuit 64 (logic combination circuit). An external indication device 68 and also external warning devices 69

  are, moreover, connected to the intermediate circuit 64.

  Each pressure adjusting member 31, 31 ′ can comprise

  ter a 31 "manual control to bring it into

  its end position (open position).

  Each regulator 62, 63 is connected to the pressure adjusting member 31 and 31 ', which is associated with it, by a conductor 30, 30' carrying the output signal. A logical combination 59 between the two regulators has the effect of cutting off the two protection systems when only one system is switched off. In this case the nominal value transmitter of the two regulators

  is controlled to occupy the zero position.

  The supply of the pressure regulating members 31, 31 'with auxiliary electrical energy (if necessary with hydraulic auxiliary energy) is effected by means of the conductors (conduits) 70, 71, 71' which connect a current source (hydraulic fluid source), not shown, to the pressure adjusting members 31, 31't

  via logic combination circuit 64.

  The instantaneous closing valve 51 is controlled

  designed in the same way as the regulating valve or valves 52. The system according to the present invention offers the following advantages: remote start and at controlled speed via the regulator for instant start and stop; operation with emergency adjustment by means of the instant stop regulator upon failure of the speed regulator;

  as a result of the logical combination of the ar-

  instantaneous shutdown of the two regulators, a redundancy is obtained

  Quadruple dance on the side of the signals and a double redundancy on the side of the regulators. As a result, the mechanical device for instantaneous stopping, the presence of which was necessary until this cheek, can be dispensed with; the additional trigger systems for instantaneous shutdown, for example the generator protection device, the emergency detection device and similar devices are integrated into the following system

the invention.

  Consequently, the present invention relates to an electronic system for adjusting the speed and for triggering the instantaneous shutdown of a turbine,

  this system comprising transmitters of the value ef-

  nominal, actual and actual value comparators and regulators for the turbine regulating valves, and this system allows detection

  multiple of the speed limit value.

  Special features are that a second speed control system and

  triggering of the instantaneous stop, completely identical

  tick in the first system, acts on the start valve

  rage (instantaneous closing valve) of the turbine by means of an associated and also identical regulating member, that this second system for speed regulation and triggering of instantaneous shutdown as well as the first system can be checked completely , with regard to their proper functioning, during service and without interrupting or disturbing the operation of the turbine, that the regulating members cut off the supply

  of the turbine in working fluid when the energy

  liary is lacking and / or that the proper adjustment functions can also be performed by the

start setting.

  Additional protection systems can be integrated into the system according to the invention and trigger

also instant shutdown.

Claims (5)

  1 - Adjustment and protection system for turbines which comprises one or more adjustment distributors and an instantaneous closing valve provided in the supply duct of the turbine for working fluid, tachometric probes to which an adjustment device is connected and of protection, controlling the distributors or valves, characterized in that provision is made, on the one hand, for the adjustment system and, on the other hand, for the   protection system two sensitive speed controllers   largely identical but independent of each other and   one of which is in active contact with the distributor (s)   adjustment scorers while the other is in ac-   tive with the instantaneous closing valve and in that two independent devices to measure the speed of   effective rotation are associated with each of the regulators.   2 - System according to claim 1, characterized in that the pressure adjusting members (31, 31 ') comprise a manual control making it possible to bring each time one of the control valves to the position   limit switch (open position).   3 - System according to one of claims 1 and 2,   characterized in that a coupling valve (56) is provided   to cut the auxiliary energy during instantaneous shutdown   liar (hydraulic fluid) supplying the   instant closure and adjustment valves.   4 - System according to one of claims 1 to 3,   characterized in that the pressure adjusting member (31, 31 ') serves simultaneously as an adjusting member and a member   for instant stop, instant stop   This is done by removing the auxiliary energy.   - System according to one of claims 1 to 4,   characterized in that the verification of the instant stop   This is done on the release side and without com-   mutation by superimposing on the speed signal   a control signal and deleting during verification   cation only the actual value signal by the   control signal superimposed while retaining the function   other protection circuits and by interrupting   the supply of auxiliary energy to the regulating member   pressure age (51 or 51 ') and in that the verification   is finished after this interruption and after restoring   auxiliary power supply.   6 - System according to one of claims 1 to   , characterized in that it is integrated, as a secondary system, in a primary adjustment device   (waterfall regulator, equivalence regulator and ana-   logues), the primary control circuits can then be connected both to the regulator of the instantaneous closing valve and to the regulator of the regulating valve; in this case it is possible, for example, to provide, upstream of the speed regulator, a constant speed regulator and upstream of the starting regulator, another regulator intended for the protection of other elements of the installation (pump regulator, charge for a boiler).