ISA TR77 30 01-2015 Power Plant Control System Dynamic Performance Test Methods and Procedures.pdf

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1、 TECHNICAL REPORT A Technical Report prepared by ISA and registered with ANSI ANSI/ISA-TR77.30.01-2015 Power Plant Control System Dynamic Performance Test Methods and Procedures Approved 5 July 2015 Copyright 2015 ISA. All rights reserved. ANSI/ISA-TR77.30.01-2015 Power Plant Control System Dynamic

2、Performance Test Methods and Procedures ISBN: 978-1-941546-68-0 Copyright 2015 by ISA. All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic mec

3、hanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher. ISA 67 Alexander Drive P.O. Box 12277 Research Triangle Park, North Carolina 27709 - 3 - ANSI/ISA-TR77.30.01-2015 Copyright 2015 ISA. All rights reserved. Preface This preface, as well as all foot

4、notes and annexes, is included for information purposes and is not part of ANSI/ISA-TR77.30.01-2015. This document has been prepared as part of the service of ISA toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subjec

5、t to periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fax (919) 549-8288; E-mail: s

6、tandardsisa.org. The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits

7、to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce SI-acceptable metric units in all new and revised standards, recommended

8、practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (SI): The Modern Metric System, published by the American Society for Testing ramp test, V-notch test, and step test. Based on the users test objective for a load change test, the

9、appropriate test method can be defined in the test plan. Regardless of the load change test method used, the same test method must be used when determining any control performance improvements. Repeating the same test method will ensure that the corresponding parameter deviation will provide a good

10、index when computing the degree of control improvement. 7.3.1 Ramp tests A ramp test ramps the load setpoint up and down (or down and up) between two steady load points at the desired unit ramp rate. The initial load ramp direction can be up or down based on the needs of the unit. Figure 7.1 illustr

11、ates a load setpoint profile for a ramp test. The user needs to define the following ramp test parameters: 1) Initial load setpoint: The initial load setpoint is an arbitrary setpoint but should not be at the minimum or maximum unit load limits. - 23 - ANSI/ISA-TR77.30.01-2015 Copyright 2015 ISA. Al

12、l rights reserved. 2) Ending load setpoint: The load range of the ramp should be large enough to cause all process variables to exceed their normal deviation band limits, typically greater than 10% of the maximum load of the unit. If the desired test is to verify tuning within a load range then the

13、end load setpoint may be 10% of maximum load above the starting load point. If the desired test is to verify the controllability with the fuel delivery turndown then the end load setpoint can be calculated based on the fuel delivery capacity. If the designed test is to verify the controllability whe

14、n pulverizers are added or removed from service then the end load setpoint can be calculated based on the pulverizer capacity. Normally the upper end point of the load ramp test is not at the units high load limit. However, on some units it may be desirable to document the control system performance

15、 as the unit ramps into the high load limit. Some control systems have logic which reduces the load rate of change as the units high load limit is approached and this test would be useful for verifying that such logic is operating properly. Because overfiring is required during a load increase, the

16、load ramp end point should be slightly below the full load capability of the unit. 3) Load rate of change: The load rate of change is determined by the plants desired operating ramp rate or contract specified ramp rate. The type of fuel, fuel delivery system, and process dynamics will be a factor in

17、 the actual operating ramp rate. 4) Process settling time: The largest process settling time is typically the steam temperature variable. The steam temperature settling time will vary as a function of load and magnitude of the load ramp. t 1 t 2 t 3 t 4 t 5 t 6X 1X 2Figure 7-1 Ramp test profile ANSI

18、/ISA-TR77.30.01-2015 - 24 - Copyright 2015 ISA. All rights reserved. The test method is as follows: 1) Manually set load setpoint to a desired unit load (X1) (start data collection). 2) Hold load setpoint for a period of the largest process settling time (t2). 3) Set new load setpoint (X2) and ramp

19、at the desired ramp rate. 4) Hold load setpoint for a period of the largest process setting time (t4). 5) Set new load setpoint (X1) at the desired ramp rate. 6) Hold load setpoint for a period of the largest process settling time (t6). Stop data collection. The plant equipment turndown capabilities

20、 determine the maximum load change magnitude during the load ramp. In practically all cases, the ramp magnitude is large enough to change the energy inventory within the boiler. Thus, the test will validate the feedforward as well as the feedback control strategies. Dispatchers often prefer the ramp

21、 test rather than the V-notch test because the ramp test creates less grid frequency upset. Furthermore, operators find the ramp test easier to perform. 7.3.2 V-notch ramp test A V-notch ramp test begins at a steady load point from which the load is ramped either up or down as desired. When the load

22、 setpoint reaches the end point of its first ramp, the load setpoi nt is immediately ramped in the opposite direction until the end point of that ramp is reached. This ramping cycle may be repeated again if desired. The last ramp segment brings the load setpoint back to the starting load point where

23、 it is held until the transient has settled out. Figure 7-2 illustrates the load setpoint profile for a V-notch test. The user needs to define the following ramp test parameters: 1) Initial load setpoint: The initial load setpoint is typically mid value within a load area where tuning is to be verif

24、ied. 2) Upper and lower ramp load setpoints: The load deviation setpoint should be large enough to cause all process variables to exceed its normal deviation band limits. The load deviation setpoint should not exceed the turndown/capacity of plant equipment. 3) Load rate of change: The load rate of

25、change is determined by plants desired operating ramp rate or contract specified ramp rate. The type of fuel, fuel delivery system, and process dynamics will be a factor in the actual operating ramp rate. 4) Process settling time: The largest process settling time is typically the steam temperature

26、variable. The steam temperature settling time will vary as a function of load and magnitude of end loading setpoint change. - 25 - ANSI/ISA-TR77.30.01-2015 Copyright 2015 ISA. All rights reserved. X 1X 2X 3t 1 t 2 t 3 t 4 t 5 t 6 t 7 t 8 Figure 7-2 V-notch ramp test profile The test method is as fol

27、lows: 1) Manually set load setpoint to a desired unit load (X1) (start data collection). 2) Hold load setpoint for a period of the largest process settling time (t2) 3) Set new load setpoint (X2) and ramp at the desired ramp rate 4) When load setpoint reaches X3, set new load setpoint (X2) and ramp

28、at the desired ramp rate. 5) When load setpoint reaches X2, set new load setpoint (X3) and ramp at the desired ramp rate. 6) When load setpoint reaches X3, set new load setpoint (X1) and ramp at the desired ramp rate. 7) Hold load setpoint for a period of the largest process settling time (t8). Stop

29、 data collection. Depending on the V-notch magnitude, the calculated control system performance will differ. Loops with short time constants tend to have large deviations because the derivatives and kickers tend to cause overshoot in the controls. Processes with longer time constants (e.g., temperat

30、ure) tend to have smaller deviations, because the process delays tend to average the fluctuations in the load demand. In some plants, a small V-notch magnitude change will look more like a large disturbance rather than a load change. These small V-notch changes often are not large enough in magnitud

31、e to significantly change the energy inventory within the boiler. Thus, the test is not validating the feedforward of the control strategy since the load change is not of sufficient magnitude or duration to change the energy inventory within the boiler. Therefore, the V-notch test should be used to

32、mimic a load dispatchers cyclic demand but not a sustained load change. 7.3.3 Step test The step test toggles the load setpoint up and down (or down and up) between two steady load points with no unit ramp rate. Figure 7.3 illustrates the load setpoint profile for a step test. The user needs to defi

33、ne the following ramp test parameters: 1) Initial load setpoint The initial load setpoint is an arbitrary setpoint not near (i.e., 10%) the minimum or maximum unit load limits. 2) Ending load setpoint The ending load setpoint should be large enough to cause all process variables to exceed its normal

34、 deviation band limits. The load deviation setpoint should not exceed the turndown/capacity of plant equipment. ANSI/ISA-TR77.30.01-2015 - 26 - Copyright 2015 ISA. All rights reserved. 3) Process settling time The largest process settling time is typically the steam temperature variable. The steam t

35、emperature settling time will vary as a function of load and magnitude of end loading setpoint change. X 1X 2t 1 t 2t 3 t 4t 5 t 6 Figure 7-3 Step test profile The test method is as follows: 1) Manually set load setpoint to a desired unit load (X1). (Start data collection). 2) Hold load setpoint for

36、 a period of the largest process settling time (t2). 3) Set new load setpoint (X2). 4) Hold load setpoint for a period of the largest process setting time (t4). 5) Set new load setpoint (X1). 6) Hold load setpoint for a period of the largest process settling time (t6). Stop data collection. Step tes

37、t method is a simple way to evaluate the closed loop response of a control loop. It can also be used to quantify a units ability to respond to sudden changes in system frequency. Since step changes are not a normal dispatch or operator load change, the step test is not commonly used to test coordina

38、ted mode control performance. - 27 - ANSI/ISA-TR77.30.01-2015 Copyright 2015 ISA. All rights reserved. 7.4 Runbacks Runback tests are used to verify the control system operation and performance upon a loss of a major piece of auxiliary equipment and the reduction of load to a predetermined value. Th

39、e test is used to verify the automatic operation of the runback and to quantify the controllable parameter variance from setpoint. Figure 7.4 illustrates the load setpoint profile for a runback test. The user needs to define the following ramp test parameters: 1) Initial load setpoint The initial lo

40、ad setpoint is a value that exceeds the capacity of a limited number of auxiliary equipment. 2) Final load setpoint The load deviation setpoint is a value that the unit can operate at with a limited number of auxiliary equipment. 3) Load rate of change The load rate of change is determined based on

41、the coast down time constant for a major piece of equipment. 4) Process settling time: The largest process settling time is typically the steam temperature variable. The steam temperature settling time will vary as a function of load and magnitude of end loading setpoint change. X 1X 2t 1 t 2 t 3 t

42、4 Figure 7-4 Runback test load profile ANSI/ISA-TR77.30.01-2015 - 28 - Copyright 2015 ISA. All rights reserved. 7.4.1 Boiler runbacks A boiler runback is initiated when any of the major boiler auxiliary equipment is lost: ID fan, FD fan, PA, fan, BFP, pulverizer, etc. Boiler runback can be tested in

43、 coordinated mode. The test method is as follows: 1) Manually set load setpoint to a desired unit load (X1). The desired load should achieve a 30% rate load runback. (Start data collection). 2) Hold load setpoint for a period of the largest process settling time (t2). 3) Trip major auxiliary equipme

44、nt from service. 4) The runback operation should rapidly reduce load setpoint to a load with reduced equipment operation. 5) Hold load setpoint for a period of the largest process settling time (t6). Stop data collection. 7.4.2 Turbine runback A turbine runback is initiated when any of the major tur

45、bine auxiliary equipment is lost: stator cooling temperature, electrical disruption. Turbine runback can be tested in coordinated mode. The test method is as follows: 1) Manually set load setpoint to a desired unit load (X1). The desired load should achieve a 30% rate load runback. (Start data colle

46、ction). 2) Hold load setpoint for a period of the largest process settling time (t2). 3) Trip major auxiliary equipment from service. 4) The runback operation should rapidly reduce load setpoint to a load with reduced equipment operation. 5) Hold load setpoint for a period of the largest process set

47、tling time (t6). Stop data collection. 7.5 Rundowns Rundown tests are used to verify the control system automatic operation upon a constraint in the capacity of a major piece of equipment. A load rundown is a function within the control system front end that automatically ramps the boiler firing rat

48、e (fuel and air demands) down in response to an excessive error in one or more of the boiler major sub-loop controllers (i.e., fuel, air). The rundown continues until the excessive error condition clears. Different control systems might have been configured differently depending on the philosophy of

49、 the control system designer. Determine the mode the control system goes to or stays in during a rundown. The test method is as follows: 1) Manually set load setpoint to a desired unit load (X1). Unit must be in coordinated mode. (Start data collection). - 29 - ANSI/ISA-TR77.30.01-2015 Copyright 2015 ISA. All rights reserved. 2) Hold load setpoint for a period of the largest process settling time (t2). 3) Interlock airflow demand to hold in place. 4) Increase load setpoint to generate an airflow error. The rundown operation should slowly reduce load setpoint to a load with reduce