WO2009031790A2

WO2009031790A2 - Method and system for tracing trip-cause in industrial plant

Info

Publication number: WO2009031790A2
Application number: PCT/KR2008/005139
Authority: WO
Inventors: Soonsung Lee
Original assignee: Bnf Technologe Inc.; Korea South-East Power Co., Ltd.; Korea South Power Co., Ltd.; Korea East-West Power Co., Ltd.; Korea Western Powor Co., Ltd.; Korea Midland Power Co., Ltd.
Priority date: 2007-09-03
Filing date: 2008-09-02
Publication date: 2009-03-12
Also published as: KR100852718B1; WO2009031790A3

Abstract

Disclosed is a method for tracing an industrial plant trip-cause. In the disclosed system for tra cing a trip-cause, the system including: a trip logic unit including at least one logic operator, which is for receiving a logic input signal and outputting a trip determination signal; a storage unit for storing the logic input signal and internal signals within the trip logic unit; and a tracing unit, when the trip determination signal is determined as a trip value, for tracing back an internal signal changed just before output of the trip value from among signals from an input signal for the trip determination signal to the logic input signal by stages by searching the storage unit, and detecting a trip cause logic input signal, wherein the input signal corresponds to any internal signal having the trip determination signal as an output value, from among the internal signals.

Description

METHOD AND SYSTEM FOR TRACING TRIP-CAUSE IN

INDUSTRIAL PLANT

Technical Field

[1] The present invention relates to a method and system for tracing a trip-cause in an industrial plant. More particularly, the present invention relates to a method and system for tracing a trip-cause, which include the same trip logic as a trip sensing logic within an industrial plant control system, and at the occurrence of a trip, find a trip-cause signal by tracing back the trip logic. Background Art

[2] An equipment trip accident suddenly occurring during normal plant operation results in an enormous loss in production, and causes another loss in restarting. Thus, much damage, such as an economic loss by shutdown and equipment damage by trip impact, occurs. Accordingly, it is required to quickly restart equipment by promptly finding a trip-cause and taking appropriate action, and thus to minimize economic loss caused by plant shutdown.

[3] In general, when a trip occurs in an industrial plant, a trip cause is empirically estimated with reference to event log, an SOE(Sequence Of Event) report, Trend Curve, etc., and as required, a control logic drawing of a plant distributed control system (DCS) sensing trip occurrence, an emergency operation process, etc. are analyzed in detail. All of these processes are manually carried out.

[4] Although DCS performance and advanced control techniques are continuously improved with development of computer and software technologies, there is no system for technically analyzing a trip cause in foreign countries as well as in Korea. At present, in some foreign DCSs, only certain analysis functions are applied. Moreover, analysis on a trip cause is highly dependent on a few professional people or experienced people that are skilled in an equipment operation and an industrial plant control system logic drawing. Thus, when there is no corresponding human resource at the occurrence of a trip, it is impossible to find a problem and take an action with appropriate timing.

[5] Furthermore, when there is no expert or experienced person available, difficulties in quickly finding a cause and taking actions occur, thereby prolonging a stop period of equipment and causing excessive loss in cost by shutdown. Also, even in analysis by an expert or an experienced person, since analysis and corrective actions on a plant DCS control logic drawing, and an SOE report, etc. are manually carried out, accident analysis requires considerable time and labor. Especially, in a trip accident caused by momentary influence, such as lightning surge with no reproducibility, the cause may be analyzed based only on assumption. In this case, it is impossible to quickly find the cause so as to reset equipment, thereby causing a problem of increasing burden on a plant.

Disclosure of Invention

Technical Problem

[6] Therefore, the present invention has been made in view of the above-mentioned problems, and the present invention provides a method and system, which include the same trip logic as a trip sensing logic of an industrial plant control system, and at the occurrence of a trip, find a signal causing the trip by tracing back the trip logic. Technical Solution

[7] In accordance with an aspect of the present invention, there is provided a system for tracing a trip-cause in an industrial plant, the system including: a trip logic unit including at least one logic operator, which is for receiving a logic input signal and outputting a trip determination signal; a storage unit for storing the logic input signal and internal signals within the trip logic unit; and a tracing unit, when the trip determination signal is determined as a trip value, for tracing back an internal signal changed just before output of the trip value from among signals from an input signal for the trip determination signal to the logic input signal by stages by searching the storage unit, and detecting a trip cause logic input signal, wherein the input signal corresponds to any internal signal having the trip determination signal as an output value, from among the internal signals.

[8] In accordance with another aspect of the present invention, there is provided a method of tracing a trip-cause by a trip-cause tracing system in an industrial plant, the method including the steps of: (a) sensing a trip of the industrial plant by checking a trip determination signal, setting the trip determination signal as a trace target, and storing the set trace target in a trip route; (b) searching for an input signal for the trace target to detect a current value of the input signal; (c) detecting a previous data value of the input signal by stages in reverse direction based on generation time of the current value of the input signal, comparing the previous data value with the current value of the input signal, and storing an input signal having a previous data value different from a current value, as a route signal in the trip route; (d) outputting the trip route when the route signal is an initial signal; and (e) setting the route signal as the trace target when the route signal is not the initial signal, and proceeding to step (b).

[9] The system and method according to the present invention include the same trip logic as a trip sensing logic within an industrial plant control system. Thus, it is possible to quickly take action on a trip by tracing back the trip logic and finding a trip-cause signal at the occurrence of a trip. Brief Description of the Drawings

[10] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

[11] FIG. 1 shows a control system of an industrial plant and a trip-cause tracing system according to the present invention, the trip-cause tracing system being connected to the control system;

[12] FIG. 2 shows an industrial plant trip-cause tracing system according to an embodiment of the present invention;

[13] FIG. 3 shows, in detail, a conversion unit and a trip logic unit in an industrial plant trip-cause tracing system according to an embodiment of the present invention;

[14] FIG. 4 is a flow diagram illustrating a method of tracing a trip-cause in an industrial plant, according to an embodiment of the present invention;

[15] FIG. 5 illustrates changes of an Al signal and a Bl signal at the time point of occurrence of a trip;

[16] FIG. 6 illustrates changes of a Cl signal and a C2 signal at the time point of occurrence of a trip; and

[17] FIG. 7 shows a trip logic unit including an internal conversion logic.

Mode for the Invention

[18] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawing to refer to the same or like parts. Here, for the convenience of the explanation, the same reference numerals are allotted the corresponding components to those shown in the figures in the above embodiment, and thus a repeated explanation will be omitted.

[19] FIG. 1 shows a control system of an industrial plant and a trip-cause tracing system according to an embodiment of the present invention, the trip-cause tracing system being connected to the control system.

[20] In general, the control of an industrial plant uses a distributed control system (DCS)

102 where control functions on the industrial plant are not centrally located but are distributed throughout the system.

[21] A DCS interface 104 is designed for obtaining a control signal of a DCS, and may be configured as additional hardware or software. The DCS interface 104 may obtain a control signal from a control network or an information network within the DCS 102. The control signal obtained by the DCS interface 104 may be transmitted to a trip- cause tracing system 108 according to an embodiment of the present invention via a communication network 106.

[22] FIG. 2 shows an industrial plant trip-cause tracing system according to an embodiment of the present invention.

[23] As shown in FIG. 2, an industrial plant trip-cause tracing system according to an embodiment of the present invention includes a trip logic unit 204, a storage unit 206 and a tracing unit 208.

[24] The trip logic unit 204, which includes at least one logic operator, receives a logic input signal and outputs a trip determination signal. In the present embodiment, the logic operator refers to a binary logic operator, and the logic input signal refers to a binary logic signal. 'Binary' refers to containing the digits 0 and 1. When the control signal generated from the DCS 102 is detected by the DCS interface 104 and transmitted via the communication network 106, the trip logic unit 204 receives the control signal. Herein, when a control signal to be received is not a binary value available in the trip logic unit 204, the trip logic unit 204 may allow a conversion unit 202 additionally connected thereto to convert the control signal into a logic signal according to a predetermined conversion condition so as to generate a logic input signal. In other words, the control signal, when a binary value, may be directly input to the trip logic unit 204 as a logic input signal, and on the other hand, the control signal, when not a binary value, is converted into a binary value by the conversion unit 202 and then may be input to the trip logic unit 204 as a logic input signal.

[25] The conversion condition indicates a condition for converting an input control signal into a binary value by defining a trip set point so that any one of 1 or 0 can be output. For example, if a conversion condition for a control signal transmitted from a temperature sensor is defined as "for input of 3O⁰C or more, output a logic input signal of 1, and for input of less than 3O⁰C, output a logic input signal of 0", for a control signal (transmitted from the temperature sensor) of 3O⁰C or more, ' 1 ' is output as a logic input signal, and for a control signal of less than 3O⁰C, '0' is output as a logic input signal. Herein, the conversion condition may include several conversion conditions to be successively applied, as well as only one conversion condition. For example, in addition to a conversion condition for integrating a transmitted control signal, an additional conversion condition, "for input of 3O⁰C or more, output a logic input signal of 1, and for input of less than 3O⁰C, output a logic input signal of 0" may be attached.

[26] The storage unit 206 stores a logic input signal together with an internal signal of the trip logic unit 204.

[27] Meanwhile, the trip logic unit 204 may include an internal conversion logic for receiving an internal signal and outputting the signal based on a predetermined condition. For example, the internal conversion logic may be realized as a timer logic for allowing any one internal signal within the trip logic unit 204 to be output after 3 seconds.

[28] FIG. 7 shows a trip logic unit including an internal conversion logic.

[29] As shown in FIG. 7, within the trip logic unit 204, besides an AND gate 721 and an

OR gate 723, an internal conversion logic such as a timer logic 722 may exist, and logic input signals 711, 712 and 713 are input to the trip logic unit. Herein, when a predetermined condition "output after 3 seconds" is given to the timer logic 722, the same logic signal as a first internal signal 714 is output as a second internal signal 715 after a delay time of 3 seconds from the time point at which the first internal signal 714 is input to the timer logic 722.

[30] Meanwhile, in FIG. 7, signals stored in the storage unit 206 include the logic input signals 711, 712 and 713 together with the first internal signal 714 and the second internal signal 715 as internal signals.

[31] When the trip determination signal 704 is determined as a trip value, the tracing unit

208 checks from an input signal for the trip determination signal 704 (from among internal signals within the trip logic unit 204, an internal signal having a trip determination signal as an output value) to a logic input signal by stages in reverse direction by searching the storage unit 206, and detects a trip cause logic input signal.

[32] The process in which the tracing unit 208 checks a trip determination signal output from the trip logic unit 204 and detects the trip cause logic input signal will be described in detail with reference to FIG. 3.

[33] FIG. 3 shows, in detail, the conversion unit 202 and the trip logic unit 204 in an industrial plant trip-cause tracing system according to an embodiment of the present invention.

[34] As shown in FIG. 3, in an industrial plant trip-cause tracing system according to an embodiment of the present invention, five control signals for monitoring the occurrence of a trip are input to the conversion unit 202, and the conversion unit 202 includes a first conversion unit 331, a second conversion unit 332, a third conversion unit 333, a fourth conversion unit 334, and a fifth conversion unit 335 having conversion conditions for input control signals, respectively. Also, as shown in FIG. 3, the trip logic unit 204 may be configured to include an AND gate, an OR gate, etc. In the present embodiment, the trip logic unit 204 includes a first AND gate 321, a second AND gate 322, a first OR gate 323 and a second OR gate 324.

[35] As shown in FIG. 3, the five control signals (that is, a first control signal 341, a second control signal 342, a third control signal 343, a fourth control signal 344, and a fifth control signal 345) are converted into logic input signals (that is, a Cl signal 311, a C2 signal 312, a C3 signal 313, a C4 signal 314, and a C5 signal 315) through the first conversion unit 331, the second conversion unit 332, the third conversion unit 333, the fourth conversion unit 334, and the fifth conversion unit 335, respectively, and are input to the trip logic unit 204. Herein, from among control signals, a signal transmitted as a binary value capable of being input to the trip logic unit 204 may be directly transmitted to the trip logic unit 204 by bypassing the conversion 202. In this case, a conversion condition may be "for input of 1, output a logic input signal of 1, and for input of 0, output a logic input signal of 0."

[36] Also, in the storage unit 206, an Al signal 301 output from the first AND gate 321, an A2 signal 302 output from the second AND gate 322, and a B 1 signal 303 output from the first OR gate 323 are stored as internal signals, and also the Cl signal 311, the C2 signal 312, the C3 signal 313, the C4 signal 314, and the C5 signal 315 are stored as logic input signals.

[37] In FIG. 3, it is assumed that when the trip determination signal 304 output from the trip logic unit 204 is 1, the value is a trip value.

[38] When the trip determination signal is determined as a trip value, the storage unit 206 is searched so as to check from an input signal for the trip determination signal, which has been changed just before the trip value is output, to a logic input signal by stages in reverse direction and then a trip cause logic input signal is detected. Herein, in checking from the input signal for the trip determination signal to the logic input signal by stages in reverse direction, other internal signals positioned on a checking route are also checked. In other words, as shown in FIG. 3, signals are checked by stages in sequence of the trip determination signal 304, the Al signal 301, and the C2 signal 312.

[39] The process of tracing the C2 signal 312 is as follows. If logic input signals, such as the Cl signal 311 = 1, the C2 signal 312 = 0, the C3 signal 313 = 0, the C4 signal 314 = 0 and the C5 signal 315 = 0, are input to the trip logic unit 204, internal signals of the trip logic unit may include the Al signal 301 = 0, the A2 signal 302 = 0, and the Bl signal 303 = 0. Accordingly, the trip determination signal 304 may be 0, which is not a trip value, but a normal value.

[40] Herein, it is assumed that the value of the second control signal 342 has been changed so that the C2 signal 312 was changed from 0 to 1. Then, the Al signal 301, one of the internal signals, is changed to 1, thereby changing the trip determination signal 304 output from the second OR gate 324 to 1. In other words, the trip determination signal 304 has a trip value.

[41] If the trip determination signal 304 has a trip value, the tracing unit 208 traces back a logic of the trip logic unit 204 with reference to data (including previous data) stored in the storage unit 206, and traces a trip cause signal.

[42] Accordingly, when the trip determination signal 304 has a trip value, the tracing unit

208 may detect the most recently changed input signal from among signals input to the second OR gate 324, and thus detect that the Al signal 301 was changed from 0 to 1 just before occurrence of a trip. Also, subsequently, the tracing unit 208 may detect the most recently changed input signal from among signals input to the first AND gate 321 by tracing back the Al signal 301, and thus detect that the C2 signal 312 was changed from 0 to 1 just before the occurrence of the trip. Herein, since there is no previous internal signal of the detected C2 signal 312 in the trip logic unit 204, the C2 signal 312 is determined to be an initial signal, and equipment which has generated a second control signal (corresponding to the C2 signal 312 before logic input signal conversion) is determined to be trip cause equipment. In tracing back trip-cause equipment after the occurrence of a trip as described above, a method of searching and tracing data of the storage unit 206 will be described in detail with reference to FIG. 4 illustrating an industrial plant trip-cause tracing method according to an embodiment of the present invention.

[43] FIG. 4 is a flow diagram illustrating an industrial plant trip-cause tracing method according to an embodiment of the present invention.

[44] In the same manner as FIG. 3, the flow diagram of FIG. 4 illustrates the method by giving an example in which, when input signals, such as a Cl signal 311 = 1, a C2 signal 312 = 0, a C3 signal 313 = 0, a C4 signal 314 = 0 and a C5 signal 315 = 0 are input to a trip logic unit 204, the C2 signal 312 is changed from 0 to 1, thereby causing a trip.

[45] When detecting a trip of an industrial plant by checking a trip determination signal

304 of the trip logic unit 204 in step S402, a tracing unit 208 of a trip-cause tracing system sets the trip determination signal 304 as a trace target, and stores the setting in a trip route in step S404.

[46] After setting the trace target, the tracing unit 208 checks all input signals for the trace target by searching a storage unit 206, and detects current values of all the input signals in step S406. In other words, the tracing unit 208 checks input signals of the trip determination signal 304, that is, internal signals such as an Al signal 301 and a Bl signal 303, and then detects current values (the Al signal = 1, and the Bl signal = 0).

[47] After detecting the current values of all the input signals, the tracing unit 208 detects previous data values of the current values of all the input signals by checking the storage unit 206, in which, based on the generation time of the current values, the previous data values are detected by stages in reverse direction. Herein, when an input signal having previous data values different from the current values is found, the step of setting the input signal as a route signal is performed. This will be described with reference to FIGs. 5 and 6.

[48] FIG. 5 illustrates changes of the Al signal 301 and the Bl signal 303 at the time point of occurrence of a trip. [49] In the present embodiment, a time interval for detecting a trip determination signal and an internal signal was assumed to be 100ms. As shown in FIG. 5, when it is assumed that the Al signal and the Bl signal were changed with the passage of time at the time point of occurrence of a trip, the trip occurred at 12:00:00.000, that is, at 12 o'clock, and herein, current values are as follows: the Al signal = 1, and the Bl signal = 0.

[50] In this case, after detecting previous data values of the current values in step S408, data values (the Al signal = 0, and the Bl signal = 0) occurred at 11:59:59.900 are detected. Accordingly, as an input signal having previous data values different from the current values (the Al signal = 1, and the Bl signal = 0), the Al signal 301 is detected in step S410, and then the detected Al signal is stored as a route signal in a trip route in step S414.

[51] After storing the Al signal 301 as the route signal, it is checked if the Al signal 301 is an initial signal or not in step 416. Since the Al signal is not an initial signal, the Al signal is set as a trace target in step S420. Then, all input signals on the trace target are checked by searching the storage unit 206 and current values of all the input signals are detected in step S406. In other words, input signals for the Al signal 301 (a Cl signal 311 and a C2 signal 312) are checked so as to detect the current values (the Cl signal = 1, the C2 signal = 1).

[52] After detecting the current values of the all the input signals, previous data values of the current values of all the input signals are detected by checking the storage unit 206, in which, based on the generation time of the current values, the previous data values are detected by stages in reverse direction. Herein, when an input signal having previous data values different from the current values is found, the step of setting the input signal as a route signal is performed.

[53] FIG. 6 illustrates changes of the Cl signal and the C2 signal at the time point of occurrence of a trip.

[54] As shown in FIG. 6, when it is assumed that the Al signal and the Bl signal were changed with the passage of time at the time point of occurrence of a trip, the trip occurred at 12:00:00.000, that is, at 12 o'clock, and herein, current values are as follows: the Cl signal = 1, and the C2 signal = 1.

[55] In this case, after detecting previous data values of the current values in step S408, data values (the Cl signal = 1, and the C2 signal = 1) occurred at 11:59:59.900 are detected. Accordingly, when an input signal having previous data values different from the current values (the Cl signal = 1, and the C2 signal = 1) is checked in step S410, it is determined that there is no input signal having different values.

[56] Then, previous data values at one-step previous stage are detected in step S408.

Herein, data values (the Cl signal = 1, the C2 signal = 0) occurred at the time of 11:59:59.800 prior to the time of 11:59:59.900 are detected in step S408. Accordingly, as an input signal having previous data values different from the current values (the Cl signal = 1 and the C2 signal = 1), the C2 signal is detected in step S410, and then the detected C2 signal 312 is stored as a route signal in a trip route in step S414.

[57] After storing the C2 signal as the route signal, it is checked if the C2 signal is an initial signal or not in step 416. Since the C2 signal is an initial signal in a trip logic, a trip route is output in step S418 and the process is finished.

[58] Herein, the output trip route includes a trip determination signal 304, the Al signal

301 and the C2 signal 312.

[59] Accordingly, when the trip route is traced back in this manner, it is determined that the second control signal 342 (corresponding to the C2 signal 312 before conversion) caused a trip, and also, equipment generating the second control signal 342 corresponds to trip-cause equipment.

[60] In the present invention, since analysis information on a trip cause is provided, even an unskilled operator can easily determine the trip cause and can take a quick and appropriate action at occurrence of a trip. Through development of a new technology on such trip-cause trace, it is expected that equipment management efficiency and the working ratio of an industrial plant are improved and also for trip cause analysis and corrective actions which are highly problematic in home industries, the rate of dependence on experts is reduced. Industrial Applicability

[61] As described above, the present invention is applied to a method and system for tracing a trip-cause in an industrial plant control system. In the method and system according to the present invention, the same trip logic as a trip sensing logic of an industrial plant control system is included, and at occurrence of a trip, a trip-cause signal is found by tracing back the trip logic. Thus, through the present invention, it is possible to quickly take corrective action on a trip.

[62] Although several exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Thus, it is intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, which are intended to define the scope of this invention.

Claims

[1] A system for tracing a trip-cause in an industrial plant, the system comprising: a trip logic unit comprising at least one logic operator, which is for receiving a logic input signal and outputting a trip determination signal; a storage unit for storing the logic input signal and internal signals within the trip logic unit; and a tracing unit, when the trip determination signal is determined as a trip value, for tracing back an internal signal changed just before output of the trip value from among signals from an input signal for the trip determination signal to the logic input signal by stages by searching the storage unit, and detecting a trip cause logic input signal, wherein the input signal corresponds to any internal signal having the trip determination signal as an output value, from among the internal signals.

[2] The system as claimed in claim 1, wherein the tracing unit detects a previous data value of the input signal by stages in reverse direction based on generation time of a current value of the internal signal, compares the previous data value with the current value of the internal signal, and traces an internal signal having a previous data value different from a current value, as the internal signal changed just before the output of the trip value.

[3] The system as claimed in claim 1, further comprising a conversion unit for receiving a control signal within the industrial plant, converting the control signal into a logic input signal based on a predetermined conversion condition, and outputting the logic signal.

[4] The system as claimed in claim 1, wherein the trip logic unit comprises an internal conversion logic for receiving the internal signal and outputting the internal signal based on a predetermined condition.

[5] A method of tracing a trip-cause by a trip-cause tracing system in an industrial plant, the method comprising the steps of:

(a) sensing a trip of the industrial plant by checking a trip determination signal, setting the trip determination signal as a trace target, and storing the set trace target in a trip route;

(b) searching for an input signal for the trace target to detect a current value of the input signal;

(c) detecting a previous data value of the input signal by stages in reverse direction based on generation time of the current value of the input signal, comparing the previous data value with the current value of the input signal, and storing an input signal having a previous data value different from a current value, as a route signal in the trip route;

(d) outputting the trip route when the route signal is an initial signal; and

(e) setting the route signal as the trace target when the route signal is not the initial signal, and proceeding to step (b).