Intelligent fault-tolerant control method for axial compressor control system

Abstract

The application discloses an intelligent fault-tolerant control method of an axial flow compressor control system, which comprises the following steps: collecting throat differential pressure delta P, exhaust pressure P2 and inlet temperature T1 by adopting three-redundancy design; setting the local maximum temperature as the upper limit of temperature compensation; designing temperature sensor disconnection and automatic correction; and predicting the surge occurrence of the unit according to the change of the exhaust pressure P2 speed vector, and making an intervention action in advance. The intelligent fault-tolerant design method is used to automatically judge, compensate, inhibit, eliminate, correct faults in a combination of hardware fault tolerance and software fault tolerance, so as to ensure that the equipment continues to operate safely, efficiently and reliably, or to ensure that the unit completes the predetermined function within the specified time at the cost of part of the performance of the unit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of axial flow compressor control system, and particularly relates to an intelligent fault-tolerant control method of an axial flow compressor control system. BACKGROUND

[0002] The axial flow compressor is mainly applied to air supply for devices such as metallurgical blast furnace, petrochemical regenerator, pharmaceutical and maleic anhydride reaction tank (hereinafter collectively referred to as device), as a core large-scale air supply equipment, various specifications and models of air supply flow are 1300-10000 Nm 3 / min, and exhaust pressure is 320 KPa(A)-640 KPa(A). Referring to Figure 2 , air passes through an air filter 1, is compressed by an axial flow compressor 2, and then passes through a check valve 3, an air supply valve 4 and a flowmeter 5 to supply air to the device. When the axial flow compressor 2 normally supplies air, an anti-surge valve 6 is closed. When the axial flow compressor 2 fails to operate safely (the safe operation is a self-protection operation state of the axial flow compressor without shutdown, which is a process interlocking protection or a self-protection operation state after artificial misoperation after the axial flow compressor appears surge condition, and belongs to an operation accident of the axial flow compressor), the check valve 3 is fully closed, the air supply valve 4 is fully closed, the axial flow compressor 2 is closed to 22° in the angle of the static vane, the anti-surge valve 6 is opened, and the compressed air passes through the anti-surge valve 6 and is discharged through a discharge muffler 7.

[0003] As a key core equipment for supplying air to the device, whether the axial flow compressor can normally operate is directly related to whether the device can normally produce. In the past axial flow compressor control system, due to the failure of the throat differential pressure transmitter, the exhaust pressure transmitter, the inlet temperature sensor and the bearing temperature sensor of the unit involved in the tripping, the axial flow compressor safety operation or shutdown occurs from time to time. In order to completely solve these problems, the axial flow compressor control system adopts the concept of intelligent fault-tolerant design.

[0004] Referring to Figure 3 , according to the characteristics of the axial flow compressor, when the unit normally operates, the working condition point can only operate in the area between the surge line and the choke line. If the throat differential pressure signal is lost, the working condition point quickly moves to the left and touches the surge line, the conventional anti-surge control program will make the axial flow compressor operate safely, and the unit cannot supply air to the device; if the exhaust pressure P2 signal is lost, the ordinate of the working condition point will drop to 0, that is, the working condition point will be below the choke line, and the unit anti-choking control program will act.

[0005] The temperature measuring sensor of the axial flow compressor is PT100 platinum resistance, and the corresponding relationship between the resistance value and the temperature value of the PT100 platinum resistance is that the greater the resistance value, the higher the temperature. If T1 appears a broken line, the resistance value will be infinite, and the temperature will also become infinite. At this time, the surge line after temperature compensation will move downward until it touches the working condition point, and the anti-surge program control of the axial flow compressor will act to cause the safe operation accident of the unit to occur.

[0006] Reference Figure 2 and Figure 3 The sudden increase of the pipe network resistance will cause the exhaust pressure P2 of the axial flow compressor to increase sharply, the working condition point will move upward and touch the surge line, thereby causing the safe operation accident of the axial flow compressor to occur, the check valve 3 is fully closed, the air supply valve 4 is fully closed, the anti-surge valve 6 is fully opened, the compressed air is discharged through the exhaust silencer 7, the axial flow compressor cannot supply air to the device, and the production accident of the device occurs. SUMMARY

[0007] The purpose of the present application is to solve the problem that the unit is misoperated due to the failure or malfunction of the sensor itself, thereby affecting the normal production of the device, by providing an intelligent fault-tolerant control method of an axial flow compressor control system.

[0008] To achieve the above purpose, the technical scheme adopted by the present application is:

[0009] An intelligent fault-tolerant control method of an axial flow compressor control system, comprising the following steps:

[0010] S1, three sensors A1, B1 and C1 are used to simultaneously collect the throat differential pressure ΔP, and the output value of the throat differential pressure ΔP is obtained through fault-tolerant judgment;

[0011] S2, three sensors A2, B2 and C2 are used to simultaneously collect the exhaust pressure P2, and the output value of the exhaust pressure P2 is obtained through fault-tolerant judgment;

[0012] S3, three sensors A3, B3 and C3 are used to simultaneously collect the inlet temperature T1, and the output value of the inlet temperature T1 is obtained through fault-tolerant judgment;

[0013] S4, the highest local temperature is set as the upper limit of temperature compensation;

[0014] S5, temperature sensor broken line and automatic correction design are performed;

[0015] S6, according to the change of the velocity vector of the exhaust pressure P2, the surge of the unit is predicted, and the intervention action is made in advance.

[0016] Further, the step S1 specifically comprises:

[0017] If none of the differential pressure sensors A1, B1, C1 fails, the median value of the differential pressure values in the differential pressure sensors A1, B1, C1 is selected as the output value of the throat differential pressure △P;

[0018] If any one of the differential pressure sensors fails, the high value of the differential pressure values in the remaining two differential pressure sensors is selected as the output value of the throat differential pressure △P.

[0019] Further, step S2 specifically includes:

[0020] If none of the pressure sensors A2, B2, C2 fails, the median value of the pressure values in the pressure sensors A2, B2, C2 is selected as the output value of the throat differential pressure △P;

[0021] If any one of the pressure sensors fails, the high value of the pressure values in the remaining two pressure sensors is selected as the output value of the exhaust pressure P2.

[0022] Further, step S3 specifically includes:

[0023] If none of the temperature sensors A3, B3, C3 fails, the median value of the temperature values in the temperature sensors A3, B3, C3 is selected as the output value of the intake temperature T1;

[0024] If any one of the temperature sensors fails, the low value of the temperature values in the remaining two temperature sensors is selected as the output value of the intake temperature T1.

[0025] Further, in step S4, if the temperature of the intake temperature T1 is higher than 40℃, a temperature value of 40℃ is automatically assigned as the highest temperature upper limit.

[0026] Further, in step S4, the axial flow compressor performs atmospheric pressure and temperature compensation for the exhaust pressure P2, which includes:

[0027]

[0028] Wherein, P2 is the temperature-compensated exhaust pressure value; P0 is the local average atmospheric pressure when the axial flow compressor is running; P1 is the exhaust pressure of the axial flow compressor surge test measuring point; T is the average temperature of the intake port when the axial flow compressor is surging; T1 is the current intake temperature of the axial flow compressor; K T is the isentropic index of air.

[0029] Further, step S6 specifically includes:

[0030] When the operating point moves from point A to point B, the change in exhaust pressure is:

[0031] P2差 = P 2B - P 2A

[0032] The throat differential pressure change difference is:

[0033] △P 差 = △P A - △P B

[0034] Wherein, P 2差 is the exhaust pressure difference value when the working condition point changes, P 2A is the exhaust pressure before the working condition point changes, P 2B is the exhaust pressure after the working condition point changes, △P 差 is the throat differential pressure difference value when the working condition point changes, △P A is the throat differential pressure value before the working condition point changes, △P B is the throat differential pressure value after the working condition point changes;

[0035] According to the value of △P 差 , the motion trajectory of the exhaust pressure P2 is judged, if the motion trajectory is close to the surge line, the speed vector judgment premise of the exhaust pressure P2 is established, if the motion trajectory is away from the surge line, the speed vector judgment premise of the exhaust pressure P2 is not established;

[0036] When the speed vector judgment premise is established:

[0037] P 2V = P 2差 / 50ms

[0038] Wherein, P 2V is the exhaust pressure speed vector;

[0039] When P 2V is greater than the set value, it is judged that the unit will surge, and intervention action needs to be taken.

[0040] Further, the intervention action includes:

[0041] The anti-surge valve calculates the compressed gas flow required to be released according to the flow characteristic curve of the valve, opens the anti-surge valve by a certain angle, releases the sudden increase part of the exhaust pressure to the atmosphere through the anti-surge valve and the exhaust silencer, and the working condition point falls back to point A from point B, away from the surge line, realizing early intervention to prevent the unit from surging.

[0042] The intelligent fault-tolerant control method of the axial flow compressor control system provided by the application has the following beneficial effects:

[0043] The application adopts fault-tolerant control method, sets multiple sensors, collects and controls several key measurement parameters in the operation process of the axial flow compressor, including inlet temperature T1, throat differential pressure ΔP and exhaust pressure P2, prevents the unit from malfunctioning due to sensor failure or malfunction, and affects the normal production of the device.

[0044] In the operation process, before one or more key components fail or are about to fail, the method of intelligent fault-tolerant design is used to automatically judge, compensate, suppress, eliminate and correct the fault in a combination of hardware fault tolerance and software fault tolerance, so as to ensure the safe, efficient and reliable operation of the equipment, or at the cost of part of the performance of the unit, to ensure that the unit completes its predetermined function within the specified time.

[0045] The application adopts fault-tolerant design, can realize early intervention of axial flow compressor surge, keeps the working condition point of the axial flow compressor in the safe operation area, avoids the occurrence of axial flow compressor safety operation or shutdown accidents caused by faults or errors of key detection components, realizes online replacement of the throat differential pressure sensor, the exhaust pressure sensor and the inlet temperature sensor, and reduces economic losses caused by axial flow compressor fault shutdown or stopping of air supply to the device. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 It is an intelligent fault-tolerant content diagram of the axial flow compressor control system of the application;

[0047] Figure 2 It is an intelligent fault-tolerant P&ID diagram of the axial flow compressor control system;

[0048] Figure 3 It is an axial flow compressor operation performance curve diagram;

[0049] Figure 4 It is a throat differential pressure ΔP three-redundancy intelligent fault-tolerant block diagram of the application;

[0050] Figure 5 It is an inlet and exhaust pressure P2 three-redundancy intelligent fault-tolerant block diagram of the application;

[0051] Figure 6 It is an inlet temperature T1 three-redundancy intelligent fault-tolerant block diagram of the application;

[0052] Figure 7 It is a speed vector control intelligent fault-tolerant curve diagram of the application. DETAILED DESCRIPTION

[0053] The specific embodiments of the present application are described below to facilitate the understanding of the present application for those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.

[0054] In the embodiment 1, the intelligent fault-tolerant control method of the axial flow compressor control system, the method of the embodiment can achieve that before one or more key detection components of the unit fail or are about to fail during operation, the fault is automatically compensated, suppressed, eliminated, corrected by using the theory and method of intelligent fault-tolerant control, so as to ensure that the axial flow compressor continues to operate safely, efficiently and reliably, or at the cost of part of the performance loss, the axial flow compressor can effectively supply air to the device, and the specific steps include the following steps:

[0055] Step S1, three sensors of differential pressure sensors A1, B1 and C1 are used to collect the throat differential pressure ΔP at the same time, and the output value of the throat differential pressure ΔP is obtained through fault-tolerant judgment;

[0056] Specifically, referring to Figure 4 If none of the differential pressure sensors A1, B1 and C1 fails, the median value of the differential pressure values in the differential pressure sensors A1, B1 and C1 is selected as the output value of the throat differential pressure ΔP;

[0057] If any one of the differential pressure sensors fails, the high value of the differential pressure values in the remaining two differential pressure sensors is selected as the output value of the throat differential pressure ΔP; for example, if sensor C1 fails, the high value of the sensors A1 and B1 is selected as the output value; and the same is true for Figure 4 As shown.

[0058] Step S2, three sensors of pressure sensors A2, B2 and C2 are used to collect the exhaust pressure P2 at the same time, and the output value of the exhaust pressure P2 is obtained through fault-tolerant judgment;

[0059] Specifically, if none of the pressure sensors A2, B2 and C2 fails, the median value of the pressure values in the pressure sensors A2, B2 and C2 is selected as the output value of the throat differential pressure ΔP;

[0060] If any one of the pressure sensors fails, the high value of the pressure values in the remaining two pressure sensors is selected as the output value of the exhaust pressure P2; for example, if sensor C2 fails, the high value of the sensors A2 and B2 is selected as the output value; and the same is true for Figure 5 As shown.

[0061] Step S3, three sensors A3, B3, C3 are used to collect the intake temperature T1 simultaneously, and the output value of the intake temperature T1 is obtained through fault-tolerant judgment;

[0062] Specifically, if none of the temperature sensors A3, B3, C3 is faulty, the median of the temperature values of the temperature sensors A3, B3, C3 is selected as the output value of the intake temperature T1.

[0063] If any one of the temperature sensors is faulty, the low value of the temperature values of the remaining two temperature sensors is selected as the output value of the intake temperature T1; for example, if the sensor C3 is faulty, the high value of the sensors A3, B3 is selected as the output value; and the like. Figure 6

[0064] Step S4, set the local maximum temperature as the upper limit of temperature compensation;

[0065] Specifically, the maximum temperature compensation limit is set to prevent the surge line after compensation from moving down indefinitely. According to the exhaust pressure P2 temperature compensation formula, it can be known that when the surge test is performed, the intake temperature T and the exhaust pressure P1 are constant, the larger the intake temperature T1 of the unit during operation, the smaller the exhaust pressure P2, and the surge line after compensation will move down, in order to prevent the surge line from moving down indefinitely and touching the working condition point to cause the unit to run safely. In order to prevent the unit from running safely, the local maximum temperature (such as 40℃) is set as the upper limit of temperature compensation.

[0066] When the intelligent fault-tolerant judgment T1 temperature of the embodiment is higher than 40℃, 40℃ is automatically assigned as the maximum temperature limit, and the surge line after temperature compensation will not move down after reaching the surge line compensated by 40℃, which ensures the safety of the unit. The atmospheric pressure and temperature compensation of the axial flow compressor is the compensation of the exhaust pressure P2, and the calculation method is:

[0067]

[0068] Wherein, P2 is the exhaust pressure value after temperature compensation; P0 is the local average atmospheric pressure during operation of the axial flow compressor; P1 is the exhaust pressure of the axial flow compressor at the test point; T is the average temperature of the intake port of the axial flow compressor during the surge test; T1 is the current intake port temperature of the axial flow compressor; K T The isentropic index of air is a constant 1.4.

[0069] Step S5, design of temperature sensor wire breakage and automatic correction;

[0070] ​Specifically, this step is for the breakage of PT100 platinum resistance temperature sensor and automatic correction, solves the problem that the unit measuring point temperature is higher than HH (false signal) due to the breakage of the temperature sensor, and the unit is shut down.

[0071] Table 1

[0072]

[0073]

[0074] As shown in Table 1, in the case of self-failure of the PT100 platinum resistance sensor, the PT100 measurement resistance increases, and if there is no intelligent fault-tolerant system, the bearing temperature HH will be interlocked and the unit will be shut down. The intelligent fault-tolerant system can determine whether the PT100 is in a breakage condition according to the size and mutation value of the measured resistance. If it is determined that the platinum resistance is in a breakage condition, the intelligent fault-tolerant system will read the temperature value before the breakage as the measurement value of the point and issue an alarm prompt "PT100 appears to be broken, please handle it in time". In this way, the unit shutdown accident caused by the self-failure of the measuring component is avoided.

[0075] Step S6, according to the change of the speed vector of the exhaust pressure P2, the occurrence of the surge of the unit is predicted, and the intervention action is made in advance.

[0076] This step can predict whether the unit will surge and make an intervention action in advance to ensure that the unit maintains its specified function, or sacrifices part of the performance to ensure that the unit continues to work within an acceptable range.

[0077] Specifically, when the axial flow compressor normally supplies air to the device, the axial flow compressor will be required to increase / decrease the pressure or flow according to the production demand of the device, and the operating point will move up and down or left and right by a small range. However, if the external pipe network resistance suddenly increases, it will cause the exhaust pressure P2 of the axial flow compressor to suddenly increase, and the unit is prone to surge. The anti-surge control program of the unit will close the check valve 3 and the air supply valve 4, and open the anti-surge valve 6 to ensure the safety of the unit operation. However, for the device, if the axial flow compressor stops supplying air to the device, the production loss of the device will be fatal.

[0078] In order to ensure that the unit can normally or reduce the performance to supply air to the device under the condition of sudden increase of the exhaust pressure of the axial flow compressor caused by the external pipe network, the intelligent fault-tolerant system designs a speed vector control system, which is as follows:

[0079] When the operating point moves from point A to point B, the change difference of the exhaust pressure is:

[0080] P 2差 =P 2B -P 2A

[0081] Laryngeal differential pressure change difference:

[0082] △P 差 =△P A -△P B

[0083] By△P 差 The value size determines whether the exhaust pressure P2 trajectory is close to or away from the surge line. If it is close to the surge line, the exhaust pressure P2 speed vector judgment premise is established; if it is away from the surge line, the exhaust pressure P2 speed vector judgment premise is not established, as shown in Figure 7 .

[0084] When the vector judgment premise is established, it is concluded that:

[0085] P 2V =P 2差 / 50ms

[0086] Wherein, 50ms is the control system acquisition scanning period.

[0087] When P 2V is greater than a certain value, it can be predicted that the unit will surge, and the intelligent fault-tolerant algorithm needs to be intervened.

[0088] At this time, the anti-surge valve 6 will calculate the required compressed gas flow according to the flow characteristic curve of the valve, and then quickly open the anti-surge valve 6 to a certain angle. The sudden increase in exhaust pressure is released to the atmosphere through the anti-surge valve 6 and the exhaust silencer 7. In this way, the working point will fall back from B point to A point, away from the surge line, and the unit will not surge. The check valve 3 and the air supply valve 4 can be closed, and the axial flow compressor 2 can still supply normal air to the device.

[0089] Although the specific embodiments of the invention are described in detail with reference to the accompanying drawings, it should not be understood as limiting the scope of protection of the patent. Various modifications and variations made by those skilled in the art within the scope described in the claims are still within the scope of protection of the patent.

Claims

1. An intelligent fault-tolerant control method of a control system of an axial compressor, characterized in that, It comprises the following steps: S1, three sensors A1, B1, C1 are used to collect the throat differential pressure △P simultaneously, and the output value of the throat differential pressure △P is obtained through fault-tolerant judgment; S2, three sensors A2, B2, C2 are used to collect the exhaust pressure P2 simultaneously, and the output value of the exhaust pressure P2 is obtained through fault-tolerant judgment; S3, three sensors A3, B3, C3 are used to collect the inlet temperature T1 simultaneously, and the output value of the inlet temperature T1 is obtained through fault-tolerant judgment; S4, the local maximum temperature is set as the upper limit of temperature compensation; S5, the temperature sensor disconnection and automatic correction design are carried out; S6, according to the change of the exhaust pressure P2 speed vector, the surge of the unit is predicted, and the intervention action is taken in advance; The step S1 specifically comprises: If none of the differential pressure sensors A1, B1, C1 fails, the median value of the differential pressure values in the differential pressure sensors A1, B1, C1 is selected as the output value of the throat differential pressure △P; If any one of the differential pressure sensors fails, the high value of the differential pressure values in the remaining two differential pressure sensors is selected as the output value of the throat differential pressure △P; The step S2 specifically comprises: If none of the pressure sensors A2, B2, C2 fails, the median value of the pressure values in the pressure sensors A2, B2, C2 is selected as the output value of the throat differential pressure △P; If any one of the pressure sensors fails, the high value of the pressure values in the remaining two pressure sensors is selected as the output value of the exhaust pressure P2; The step S3 specifically comprises: If none of the temperature sensors A3, B3, C3 fails, the median value of the temperature values in the temperature sensors A3, B3, C3 is selected as the output value of the inlet temperature T1; If any one of the temperature sensors fails, the low value of the temperature values in the remaining two temperature sensors is selected as the output value of the inlet temperature T1; The step S6 specifically comprises: When the operating point moves from point A to point B, the differential change of the exhaust pressure is: P 2差 =P 2B -P 2A The differential change of the throat differential pressure is: ΔP 差 = ΔP A - ΔP B wherein P 2差 is the exhaust pressure difference value when the operating point changes, P 2A is the exhaust pressure before the operating point changes, P 2B is the exhaust pressure after the operating point changes, ΔP 差 is the throat differential pressure difference value when the operating point changes, ΔP A is the throat differential pressure value before the operating point changes, ΔP B is the throat differential pressure value after the operating point changes. According to ΔP 差 The movement trajectory of the exhaust pressure P2 is judged, if the movement trajectory is close to the surge line, the exhaust pressure P2 speed vector judgment premise is established; if the movement trajectory is away from the surge line, the exhaust pressure P2 speed vector judgment premise is not established; When the speed vector judgment premise is established: P 2V =P 2差 / 50ms where P 2V is the exhaust pressure velocity vector; 50 ms is the control system acquisition scan period; When P 2V If the value is greater than a set value, it is predicted that the unit will surge and intervention is required. The intervention action comprises: The anti-surge valve opens a certain angle according to the calculated compressed gas flow required by the flow characteristic curve of the valve, and the sudden increase part of the exhaust pressure is released to the atmosphere through the anti-surge valve and the exhaust silencer, so that the operating point falls back to point A from point B, away from the surge line, and the surge of the unit is prevented in advance.

2. The intelligent fault-tolerant control method of the axial compressor control system according to claim 1, characterized in that: In the step S4, if the inlet temperature T1 is higher than 40℃, the temperature value of 40℃ is automatically assigned as the maximum temperature limit.

3. The intelligent fault-tolerant control method of the axial compressor control system according to claim 2, characterized in that: In the step S4, the atmospheric pressure and temperature compensation of the axial flow compressor is carried out to compensate the exhaust pressure P2, which comprises: Wherein, P2 is the temperature-compensated exhaust pressure value; P0 is the local annual average atmospheric pressure when the axial flow compressor is running; P1 is the exhaust pressure of the axial flow compressor surge test measuring point; is the average temperature of the inlet of the axial flow compressor during the surge test; is the current inlet temperature of the axial flow compressor; is the isentropic index of air.

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