SIST EN 61064:2000
(Main)Acceptance tests for steam turbine speed control systems
Acceptance tests for steam turbine speed control systems
Contains recommendations for the conduct of tests of speed control systems of steam turbines. Applies primarily to constant speed steam turbines but may be applied where appropriate for other types of turbines. The purpose of the tests described in this publication is to verify the criteria guaranteed by the manufacturer and to check compliance with EN 60045-1.
Abnahmeprüfungen für Dampfturbinen-Regelsysteme
Essais de réception des systèmes de régulation de vitesse des turbines à vapeur
Contient des recommandations pour la conduite des essais des systèmes de régulation de vitesse des turbines à vapeur. S'applique essentiellement aux turbines à vapeur à vitesse constante mais peut être appliquée selon le cas à d'autres types de turbines. Le but des essais est de vérifier les critères garantis par le constructeur et la conformité avec la EN 60045-1.
Acceptance tests for steam turbine speed control systems
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 61064:2000
01-junij-2000
Acceptance tests for steam turbine speed control systems
Acceptance tests for steam turbine speed control systems
Abnahmeprüfungen für Dampfturbinen-Regelsysteme
Essais de réception des systèmes de régulation de vitesse des turbines à vapeur
Ta slovenski standard je istoveten z: EN 61064:1993
ICS:
27.040 Plinske in parne turbine. Gas and steam turbines.
Parni stroji Steam engines
SIST EN 61064:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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NORME CEI
INTERNATIONALE IEC
61064
INTERNATIONAL
Première édition
STANDARD
First edition
1991-04
Essais de réception des systèmes de régulation
de vitesse des turbines à vapeur
Acceptance tests for steam turbine
speed control systems
© IEC 1991 Droits de reproduction réservés — Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
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procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in
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Pour prix, voir catalogue en vigueur
• • For price, see current catalogue
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1064©IEC – 3 –
CONTENTS
Page
FOREWORD 7
Clause
1 Scope and object 9
2 Normative reference 9
3 Terms, symbols, definitions and units 11
4 Guiding principles 15
4.1 Matters on which agreement shall be reached 15
4.2 Time of carrying out tests 17
4.3 Preparation for acceptance tests 19
4.4 Instruments 19
4.5 Test report 21
5 Speed governing system tests 21
5.1 Turbine at standstill 21
5.2 Turbine at no-load 21
5.2.1 Overview 21
5.2.2 Test procedure for determination of static characteristics 23
5.2.3 Determination of dead band 25
52.4 Speed range determination 25
5.2.5 Stability 25
5.3 Turbine on load 25
5.3.1 Overview 25
5.3.2 Test conditions 27
5.3.3 Load-steam flow demand relationship 27
5.3.4 Dead band determination - Overview 29
5.3.5 Dead band determination - Method 1 29
5.3.6 Dead band determination - Method 2 31
5.3.7 Determination of steady-state speed regulation - Method 1 31
5.3.8 Determination of steady-state speed regulation - Method 2 33
5.3.9 Determination of incremental speed regulation - Method 1 33
5.3.10 Determination of incremental speed regulation - Method 2 35
5.3.11 Stability 35
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1064©IEC –5
Clause Page
5.4 Dynamic tests of the speed governing system by sudden load rejection
to no-load 35
5.4.1 Overview 35
5.4.2 Operating conditions 35
5.4.3 Test procedure 37
5.4.4 Test results 39
5.4.5 Stability 39
6 Overspeed protection system tests 39
6.1 Turbine at standstill 39
6.2 Turbine at no-load 39
6.3 Turbine on load 41
6.4 Dynamic testing of overspeed protection system by turbine trip from maximum
load 41
6.4.1 Overview 41
6.4.2 Operating conditions 41
6.4.3 Test procedure 41
6.4.4 Test results 41
Annex A - General guidance 45
Figures 50
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1064©IEC
INTERNATIONAL ELECTROTECHNICAL COMMISSION
ACCEPTANCE TESTS FOR STEAM TURBINE
SPEED CONTROL SYSTEMS
FOREWORD
1) The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on
which all the National Committees having a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
2) They have the form of recommendations for international use and they are accepted by the National
Committees in that sense.
3) In order to promote international unification, the IEC expresses the wish that all National Committees
should adopt the text of the IEC recommendation for their national rules in so far as national conditions will
permit. Any divergence between the IEC recommendation and the corresponding national rules should, as
far as possible, be clearly indicated in the latter.
This International Standard has been prepared by IEC Technical Committee No. 5: Steam
turbines.
The text of this standard is based on the following documents:
Six Months' Rule Report on Voting
5(CO)30 5(CO)33
Full information on the voting for the approval of this standard can be found in the Voting
Report indicated in the above table.
Annex A forms an integral part of this International Standard.
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1064©IEC - 9 -
ACCEPTANCE TESTS FOR STEAM TURBINE
SPEED CONTROL SYSTEMS
1 Scope and object
This International Standard applies primarily to constant-speed steam turbines driving a.c.
generators at power stations, for testing speed control systems consisting of speed
governing and overspeed protection systems. It may also be used, where appropriate, for
other types of steam turbines.
The purpose of acceptance tests of steam-turbine speed governing and overspeed protec-
tion systems is to verify any criteria quoted in the manufacturer's guarantees. Such tests
will generally be carried out to check compliance with IEC 45-1. The criteria may include:
a) steady-state speed regulation (speed governing droop);
b) steady-state incremental speed regulation (incremental speed governing droop);
c) range of speed at no-load corresponding to the extreme settings of the speed
changer;
d) dead band of the speed governing system;
e) stability of the speed governing system;
ial
f) maximum transient increase of speed following full load rejection and any pa rt
load rejections, with the speed governing system in operation;
g) overspeed trip setting;
h) maximum transient overspeed following full load rejection on the failure of the
speed governing system.
Selection of the tests to be carried out and procedures for other tests not covered by this
specification shall be agreed upon between the manufacturer and the purchaser.
2 Normative reference
The following standard contains provisions which, through reference in this text, constitute
provisions of this International Standard. At the time of publication, the edition indicated
was valid. All standards are subject to revision, and pa rties to agreements based on this
International Standard are encouraged to investigate the possibility of applying the most
recent edition of the standard indicated below. Members of IEC and ISO maintain registers
of currently valid International Standards.
IEC 45: 1991, Steam turbines. Part 1: Specifications.
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1064 ©IEC - 11 -
3 Terms, symbols, definitions and units
Using these rules it is recommended to employ the symbols, definitions and units that are
given in tables 1 and 2 and in figure 1. Table 1 lists basic terms, symbols, and units, while
Table 2 presents terms, symbols, definitions, and units of parameters specific to this
standard. IEC 45-1 definitions are also applicable.
Table 1
Symbol Unit
No. Term
L MW or kW
1 Power or load
p MPa or bar
2 Pressure
e K or °C
3 Temperature
w rad/s
4 Angular speed
n Hz, rev/s
5 Rotational speed
(rev/min)
U V
6 Voltage
7 Current / A
s mm, rad or (°)
8 Position or stroke of servomotors
h mm, rad or (°)
9 Position or stroke of valves
x mm, rad or (°)
10 Position or stroke of pi lots
T s
11 Time constant, characteristic time of element
t s
12 lime as independent variable
or other
13 Speed or load setting point y %
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1064 0 IEC
- 13 -
Table 2
No.
Term Symbol
Definition Unit
1
Rated speed no
The speed at which the turbine is specified to operate Hz
at its rated output rev/s
rev/min
2 Minimum controlled speed
n The speed at no-load corresponding to the lower setting Hz
1
at no-load
of the speed changer rev/s
rev/min
3
Maximum controlled speed n2 The speed at no-load corresponding to the upper setting
Hz
at no-load
of the speed changer rev/s
rev/min
4
Temporary speed rise The
transient increase in turbine speed following a load Hz
rejection, with the speed governing system in operation. rev/s
The rated temporary speed rise applies If the rated output
rev/min
is rejected at rated speed
5 Maximum speed rise
The maximum transient increase in turbine speed Hz
following a load rejection, with the speed governing
rev/s
system inoperative. The rated maximum speed rise rev/min
applies if the rated output is rejected at rated speed
6
Maximum transient speed nm
The maximum transient increase in turbine speed following Hz
rejection of maximum capability by disconnecting the
rev/s
generator from the electrical system (with auxiliary supplies
rev/min
previously disconnected) and the speed governing system
in operation
7
Maximum transient overspeed noes
The maximum rotational speed following rejection of Hz
maximum capability by disconnecting the generator from rev/s
the electrical system (with auxiliary supplies previously rev/min
disconnected) and the speed governing system
inoperative
8
Overspeed trip setting ns Th
e speed at which the overspeed trip is set to operate Hz
rev/s
rev/min
9 Maximum continuous rating
L0 The power output assigned to the turbine-generator
MW
(MCR) (electrical generating
by the supplier, at which the unit may be operated for an
or
set)
unlimited time, not exceeding the specified role, at the kW
specified terminal conditions. This is the rating which will
normally carry
a guarantee of heat rate. The governing
valves will not necessarily be fully open. (Also referred to
as rated output, rated power or rated load)
10 Maximum capability
The
maximum power output that the turbine can produce MW
Lmax
with the governing valves fully open and at the spec
ified or
initi
al steam conditions. (Also referred to as valves-wide- kW
open capability or maximum load)
(Continued on page 15)
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1064 ©IEC
- 15 -
Table 2 (continued)
No. Term Symbol Definition Unit
MW
11 Maximum overload capability Lod The maximum power output that the unit can produce
or
with the governing valves fully open, and with the
kW
terminal conditions specified for overload, e.g. with final
feed water heater bypassed or with increased initial
steam pressure
12 Dead band of the speed E The total magnitude of the change in steady-state speed %
(Dimension-
governing system (expressed as a percentage of rated speed), within which
there is no resultant change in the position of the govern- less)
ing valves. The dead band is a measure of the sensitivity
of the system
13 Steady-state speed regulation & The steady-state speed change, expressed as a per- 9'0
(speed governing droop) centage of rated speed, when the load of an isolated unit (Dimension-
is changed between rated load and zero load, with less)
identical setting of the speed governing system, assuming
a zero dead band
%
14 Steady-state incremental 61 The rate of change of the steady-state speed with respect
speed regulation (incremental to load at a given steady-state speed and load, assuming (Dimension-
less)
speed droop) a zero dead band. The value is the slope of the tangent
to the steady-sate speed/load curve at the load under
consideration
15 MPa
Steam flow demand do The signal generated in the speed governing system
which represents the required steam flow to the turbine V
or
A
16 Fluid pressure in control pc Fluid pressure at different points of the hydraulic control MPa
system
system
17 Stability The capability of the speed governing system to reduce
oscillations of the speed or load resulting from the action
of the governing system to amplitudes within acceptable
limits
4 Guiding principles
4.1
Matters on which agreement shall be reached
a) The parties to the test shall, prior to the tests, reach agreement on the object of the
tests and on the interpretation of the guarantees. Unless otherwise stated in the
contract, the control system functions shall be verified in accordance with 1.2.
b) Agreement shall be reached on the method of operation and on such matters as the
means of maintaining constant steam conditions and output. If the test conditions differ
from those specified in the test program, agreement shall be reached on the methods of
conversion of experimental values.
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1064©IEC - 17 -
c) Methods of testing other than those stated in this standard may be used by mutual
agreement between the parties. For example, the methods given in national codes to
determine steady-state speed regulation, dead band and other characteristics of the
control system may be used. However, comparison of the quality of different control
systems shall be accomplished only by using the methods stated in this standard. In
the absence of such written agreement, it is understood that the provisions of this stan-
dard are to be applied.
d) Agreement shall be reached on the method and responsibilities for calibration of the
instruments.
e) The parties to the test may designate a person to direct the test and another person
to arbitrate in the event of disputes regarding test conditions and procedures, or accu-
racy of measurement and obse
rvations.
f) Accredited representatives of the purchaser and the manufacturer may be present
at the tests to verify that they are conducted in accordance with this standard and the
agreements made prior to the tests.
g) The test results shall be reported as calculated from the test observations, due
account being taken of any corrections resulting from calibration of the instruments.
Any tolerances or deviations from contractual values are a commercial matter between
purchaser and manufacturer, and are not dealt with in this standard. Agreement shall
be reached on the contents and the time period for preparation of the test repo rt.
h) If not specified in the contract, the following items shall be agreed upon between
the purchaser and manufacturer of the turbine, generator and control system:
1) supply of materials and special instrumentation to car ry out the test;
2) provision of access to the necessary measuring points on the turbine, generator
and control system;
3) time allowed for installing, pre-testing and disassembly of the test instrumen-
tation;
4) tests to be carried out at the manufacturer's works and at the power plant;
5) provision of necessary additional personnel and definition of their duties;
6) liability in case of accidents, loss or damage to equipment and instruments;
7) liability for any damage due to testing of the turbine, generator or control
system;
8) liability for any possible interruption of turbine se rvice beyond that necessary to
carry
out the test;
9) insurance against any uncovered risk;
10)
costs of equipment and manpower.
4.2 Time of carrying out tests
a) Any necessary adjustments to the speed governing and overspeed protection
systems shall be completed before performing acceptance tests.
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1064©IEC - 19 -
b) Acceptance tests of the overspeed protection system at no load shall be carried out
as soon as the turbine is put into operation after installation.
c) All other agreed to acceptance tests shall be carried out within the period agreed
between the purchaser and the manufacturer but not later than the end of the warranty
period.
4.3 Preparation for acceptance tests
ies to the tests. The program shall
a) The test program shall be prepared by the pa rt
rties, the oper-
include a list of the tests to be carried out, the responsibilities of the pa
ational conditions and test modes, instructions for the test personnel, safety measures
and test procedures.
Before undertaking the tests, the lists and calibration curves for all instrument
b)
readings used during the tests should be compiled and checked.
c) Any special instruments not supplied for normal operation that are necessary for
carrying out the tests shall be mounted on the unit.
d) When the parties concerned agree to perform tests on the turbine at standstill, the
necessary simulation equipment shall be installed.
4.4 Instruments
a) The instruments used shall have the requisite accuracy and response character-
istics to meet the test parameters and dynamic characteristics of the test processes.
In determining the dead band it is necessary to record the speed of the unit by means
of a device having an accuracy of ±0,02 % and a dead band less than 10 % of the dead
band being measured. Also, the displacement of the servomotor and steam valves, and
the change of the steam flow demand shall be measured with an accuracy of ±0,5 % of
the displacement or change which corresponds to the load change from no-load to ra-
ted load.
A precise frequency meter with a measurement accuracy of ±0,1 % of the speed of the
unit shall be used. Also, the values of the steam flow demand, the displacement of the
main servomotor and the power at the generator terminals (measured or calculated)
shall be obtained with an accuracy of ±1 %. The measurement accuracy of the par-
ameters used for converting the measured generator power to rated conditions (steam
pressure and temperature upstream and within the turbine, steam flow, etc.) shall be
adequate to obtain the above-mentioned accuracy.
b) When carrying out dynamic tests of the speed governing and overspeed protection
systems, the pertinent values shall be recorded by fast recording instruments. The
recording instruments cut-off frequency and chart speed should be suitable to obtain
the required accuracy of the measured variables. For example, the speed measurement
accuracy shall be ±0,1 % for the load rejection test and overspeed protection test at
no-load.
c)
It is preferable to carry out test measurements with special test instruments. If this
is not practicable or convenient, the normal station operational instruments may be cali-
brated and used. If they are used, it is necessary to reach an agreement about the
tolerances for the test results.
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1064©IEC –21 –
4.5 Test report
After completion of the acceptance tests, the test repo rt shall be prepared including the
shall include the follo-
test results. Unless otherwise agreed between the pa rties, the report
wing items:
a) object and scope;
agreements between the test pa rties;
b)
c) test program;
list of measurement points and instruments used, with information about their
d)
accuracy and other characteristics;
plots and tables of calibration and correction factors for the readings of test instru-
e)
ments;
f) test measurements in tabular, graphical or chart form;
g) results of the correction of test measurements to the specified conditions, if the test
conditions differ from those specified:
h) calculations of the speed governing and overspeed protection systems charac-
teristics, and their comparison with specifications and contractual requirements;
i) conclusions about the state of the speed governing and overspeed protection
systems, and appropriate recommendations.
The test report shall be signed by those persons directing the tests and confirmed by the
parties to the contract.
5 Speed governing system tests
Tests are carried out with three different operating conditions of the turbine:
a) turbine at standstill;
b) turbine at no-load;
c) turbine on load.
5.1 Turbine at standstill
The tests on the turbine at standstill demonstrate in advance whether the speed governing
system is in its proper state, and allow for checking all the instruments and training the
operating staff. With the exception of the test for obtaining the servomotor stiffness charac-
teristic, all tests are for information only and should not be considered as acceptance
tests. The servomotor stiffness characteristic is required for measuring the dead band by
the method described in 5.3.5. The test procedure is described in A.1 of annex A.
5.2 Turbine at no-load
5.2.1 Overview
Tests are carried out with the generator disconnected from the network, and with the tur-
bine speed and parameters set as listed subsequently.
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1064©IEC - 23 -
Tests are carried out to determine:
a) the dependence of the steam flow demand and valve position on changes in the
controlled parameters;
b) the dead band of the speed governor;
c) the dead band of the speed governing system with negligible or minimum steam for-
ces on the control valves;
d) the range of speed corresponding to the extreme settings of the speed changer;
e) stability.
5.2.2 Test procedure for determination of static characteristics
All parameters, which in changing their values may affect the test results, should be
a)
stabilized as closely as possible prior to the test. This condition should be maintained
during the whole test with the accuracy defined by the equipment specifications or by
the appropriate manuals. Possible acceptable deviations from the specified values are
to be agreed by the pa rties prior to the tests.
b) Determination of the dependence of both the steam flow demand signal (for
example, fluid control pressure) and the control valve position (or the position of the
main servomotor actuating the valve) upon controlled parameter changes is carried out
for three settings of the speed changer corresponding:
1) to turbine no-load at rated speed;
2) to turbine no-load at an increased speed between 1,03 n o and 1,05 no;
3) to turbine no-load at a decreased speed between 0,96 n o and 0,98 no.
c) When determining the static characteristics of the speed governing system at
turbine no-load, the rated speed no is initially set by adjusting the speed changer and
then, without changing this setting, the turbine steam flow is slowly decreased by one
of the methods described in A.2 of Annex A. This causes a speed reduction, following
which the automatic action of the speed governing system causes the turbine control
valves to open. Recording the steam flow demand signal and the positions of all the
links of the speed governing system as a function of speed, the following functions of
"n"
are obtained for decreasing speed:
dc2 (n), s2 (n), and also, as supplementary data:
172 (n) and x2 (n).
The appropriate curves are shown in figure 2.
The test is continued until the maximum possible valve stroke is reached, in most cases
exceeding the rated valve stroke h o which corresponds to rated loading. Subsequently,
the steam admission to the turbine is increased and the speed starts to rise. The same
measurements are recorded as with speed decreasing and the following functions of
"n" are obtained for speed rising:
dc1 (n), s1 (n), and also, as supplementary data:
(n) x1 (n).
and
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1064©IEC - 25 -
d) When determining the dead band of the speed governor and of the speed governing
system it is necessary to recognize that the displacement of any amplifying stage lags
behind the control signal. Therefore, the changing of speed should be carried out slo-
wly enough to exclude any distortion associated with the response time of the speed
governing system.
5.2.3 Determination of dead band
a) The dead band of the speed governor is defined as:
Ani9
£ -9
no
whereAn. is the difference of speed at the same values of steam flow demand
between the two directions of speed change (see figure 2a).
The dead band of the speed governing system with the turbine at no-load (with
b)
negligible or minimum steam forces on the control valves) will be:
An.
£-
no
is the difference of speed at the same values of the servomotor final link
where Ant
position between the two directions of speed change (see figure 2b).
5.2.4 Speed range determination
In order to determine the speed range at no-load, corresponding to the extreme settings of
the speed changer, the rotational speed is changed by adjusting the speed changer from
its lower extreme setting point to the upper extreme setting point. The minimum (n1 ) and
maximum (n2) values of the rotational speed, at which the turbine speed is controlled by
the speed governing system, are recorded (see figure 3).
5.2.5
Stability
The speed stability can be checked with the turbine at no-load by initiation of any practi-
cable perturbation, for example:
step deviations on the speed changer, or
connecting and disconnecting of auxiliaries on the generator.
The quantitative evaluation of the stability shall be agreed between the manufacturer and
purchaser.
5.3 Turbine on load
5.3.1 Overview
Tests on the turbine on load are carried out in order to determine:
a)
the dependence of the generated load on changes in steam flow demand or in the
position of the main servomotor final link;
b)
the dead band of the speed governing system taking account of the influence of
steam forces on the control valves;
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1064 ©IEC - 27 -
c) steady-state speed regulation;
d) incremental steady-state speed regulation;
e) stability.
5.3.2 Test conditions
When carrying out tests the following shall be observed:
a) The tests shall be carried out in strict compliance with the manufacturer's manuals.
b) The turbine shall be warmed up properly (preliminary operation at or near rated load
until thermal equilibrium is achieved).
c) Main and exhaust steam conditions shall be as near as practicable to the rated
values. No corrections to test results are required if the deviation of the main steam
pressure does not exceed ±1 % of the rated value and if the deviations of the main
steam temperature and the temperature upstream of the reheat stop valves do not
exceed ±5 °C.
d) The feedwater heating system shall be in operation as specified in the manu-
facturer's manual.
e) The feedwater flow shall be maintained approximately the same as the main steam
flow.
f) The thermal cycle of the turbine shall correspond to normal operation conditions.
g) The electrical network shall be substantially constant in frequency, except for tests
5.3.6 and 5.3.10.
5.3.3 Load-steam flow demand relationship
L(dc) between the generated
a) With the turbine operating on load, the relationship
load and the steam flow demand signal, and the relationship L(s) between the gener-
ated load and the position of the main servomotor final link (or the position of servo-
motors in the case of several servomotors for the turbine) are determined. See figure 4.
b) During the above test a), the load is changed by steps of approximately 0,05 Lo
from rated load to the lowest practicable load.
An additional measurement may be made at minimum load at the highest temperature and
pressure attainable by the steam supply system.
After attaining the next load level and the necessary steam conditions, the unit operational
conditions shall be kept constant for 5 min to 10 min before the test. The observations
shall be made at intervals of 2 min to 3 min. At each electrical load, 3 to 5 sets of obser-
vations shall be made.
The above tests shall be repeated with the turbine load increasing from lowest load to
rated load. It may be desirable to carry out tests at electrical loads around the opening
points of each turbine control valve.
If it is possible to maintain stable thermal steam conditions the tests may also be per-
formed by continuously varying the load and simultaneously recording the indicated
parameters.
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1064©IEC - 29 -
For both methods all the parameters needed for correcting the results of the tests to the
rated conditions shall be recorded.
5.3.4 Dead band determination - Overview
The dead band of the whole speed governing system, taking into account the effect of
steam forces on the control valves can be determined by two different methods:
- method 1 is based on the measurements of the individual dead bands of the speed
governor when the turbine is at no-load (5.2.3a) and of the servomotor when the turbine
is on load;
- method 2 is based on the direct measurement of the total dead band between fre-
quency and load when the turbine is on load.
Method 1 may be used for all ty
pes of speed (frequency) governing systems. For systems
with closed loop load control, the integral load governor shall be taken out of operation.
This method gives the possibility of obtaining the speed governing systems' dead band for
the whole steady state regulation range.
5.3.5 Dead band determination - Method 1
a)
The main servomotor dead band, taking into account the effect of steam forces, is
determined with the turbine operating on load. With increasing load set point at several
load levels (including the points of opening of each valve) the cylinder fluid pressure (or
the fluid pressure on each side of the piston in the case of a double-acting servomotor)
is recorded. The procedure is then repeated with decreasing load set point. The
positions of the servomotor and the valve are simultaneously recorded. The dead band
of the servomotor at any position (in absolute units) is the difference
(Os) between the
cylinder pressure values at this position for increasing and decreasing the load set
points (the sum of the absolute values of such pressure differences on both sides, in
case of the double-acting servomotor) (figure 5). The servomotor dead band percent is
the ratio of the steam flow demand change Ad
s necessary to attain the above-
mentioned pressure difference Aps
with the motionless position, to the steam
...
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