Protection method for preventing sudden change of temperature measurement value based on DCS (Distributed Control System)

Abstract

The invention discloses a DCS system-based protection method for preventing sudden change of a temperature measurement value, and relates to the technical field of thermal power plant DCS logic protection. In the prior art, if a temperature measurement value fluctuates greatly or a temperature measurement point is damaged, electric power production is influenced, and even logic protection action is triggered, so that normal operation of equipment is influenced. According to the method, various DCS logic blocks are configured, sudden change of a temperature measurement value is prevented logically, and meanwhile, quality judgment can be carried out. The problem of temperature measurement in the power production process is solved. Aiming at the judgment problems that the sudden change of the temperature measurement value cannot be prevented and the quality is lack of response in the prior art, the temperature measurement logic protection for preventing the sudden change of the temperature measurement value and carrying out quality judgment is realized.

Description

Technical Field

[0001] The invention relates to the technical field of DCS logic protection of thermal power plants, in particular to a protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system. Background Art

[0002] In power generation, automation technology is increasingly being applied. This improves production efficiency while reducing manual errors and enhancing the stability of equipment. Distributed computer control systems (DCS) are widely used in power generation process control. Temperature measurement points (such as thermocouples and RTDs) are often required in power generation processes. These temperature measurement points transmit the measured temperature values ​​as analog quantities to the DCS system, which then processes the data. DCS systems typically include comparison function blocks that convert analog quantities into switching values, triggering logical protection actions.

[0003] Temperature measurement plays an important role in the power production process. If the temperature measurement value fluctuates greatly or the temperature measurement point is damaged, it will affect the power production and even affect the normal operation of the equipment, triggering the logic protection action, and then causing a safety accident. In the power production process, it is necessary not only to ensure the normal operation of the temperature measurement point and timely feedback the real working conditions of the power generation equipment, but also to prevent the sudden change of the temperature measurement value from triggering the logic protection action to avoid causing unplanned shutdown of the power equipment. In the existing technology, only the temperature measurement value is supported to trigger the logic protection action through the comparison function block of the DCS system. The sudden change of the temperature measurement value and the lack of response to the quality judgment pose a safety hazard in the power production process. Therefore, it is necessary to find a temperature measurement logic protection method that can prevent the sudden change of the temperature measurement value and perform quality judgment. Summary of the Invention

[0004] The purpose of the present invention is to address the shortcomings of the above-mentioned technology, that is, to provide a protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system, in order to solve the problems that the existing technology cannot prevent sudden changes in temperature measurement values ​​and lacks responsive judgment of quality, so as to realize temperature measurement logic protection that prevents sudden changes in temperature measurement values ​​and can perform quality judgment.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system, the specific configuration process and method of which are as follows:

[0006] Step 1: Build a TRANSPORT analog delay function block and a DBEQUALS analog high-low value comparison function block in the DCS system. The analog temperature value serves as the input of the TRANSPORT analog delay function block, and the output of the TRANSPORT analog delay function block serves as one input of the DBEQUALS analog high-low value comparison function block; the analog temperature value serves as the other input of the DBEQUALS analog high-low value comparison function block. The DBEQUALS analog high-low value comparison function block compares the two input values ​​and obtains an output;

[0007] Step 2: Build an OR gate function block and a QUALITYMON quality judgment function block in the DCS system. The analog temperature value serves as the input of the QUALITYMON quality judgment function block, and the output of the QUALITYMON quality judgment function block serves as one input of the OR gate function block; the output of the DBEQUALS analog high and low value comparison function block serves as the other input of the OR gate function block;

[0008] Step 3: Build a HIGHMON high limit function block, a NOT gate function block, and an AND gate function block AND1 in the DCS system. The NOT gate function block includes a NOT gate function block N1, a NOT gate function block N3, and a NOT gate function block N3. The analog temperature value in step 1 serves as the input of the HIGHMON high limit function block, the output of the HIGHMON high limit function block serves as the input of the NOT gate function block N1, and the output of the NOT gate function block N1 serves as an input of the AND gate function block AND1; the output of the DBEQUALS analog high and low value comparison function block in step 1 serves as the input of the NOT gate function block N2, and the output of the NOT gate function block N2 serves as an input of the AND gate function block AND1; the output of the QUALITYMON quality judgment function block in step 2 serves as the input of the NOT gate function block N3, and the output of the NOT gate function block N3 serves as an input of the AND gate function block AND1;

[0009] Step 4: Build the FLIPFLOP function block and the ONESHOT signal conversion function block in the DCS system. The output of the OR gate in step 2 serves as the SET input of the FLIPFLOP function block. The output of the AND gate function block AND1 in step 3 serves as the input of the ONESHOT signal conversion function block. The output of the ONESHOT signal conversion function block serves as the RESET input of the FLIPFLOP function block. The output of the FLIPFLOP function block serves as the input of the temperature measurement value sudden change alarm function block.

[0010] Step 5: Build the ONDELAY delay function block, AND gate function block AND2, and NOT gate function block N4 in the DCS system. The output of the HIGHMON high limit function block in step 3 serves as the input of the ONDELAY delay function block, and the output of the ONDELAY delay function block serves as one input of the AND gate function block AND2. The output of the FLIPFLOP function block in step 4 serves as the input of the NOT gate function block N4, and the output of the NOT gate function block N4 serves as the other input of the AND gate function block AND2. The output of the AND gate function block A2 serves as the input of the temperature measurement value sudden change protection function block.

[0011] Furthermore, the input value and output value of the TRANSPORT analog delay function block are consistent. By setting the delay time, the TRANSPORT analog delay function block has a delay function and will output the value after the delay time.

[0012] Furthermore, the DBEQUALS analog high / low comparison function block has two analog inputs and a switch output. When the absolute value of the difference between the two analog input signals is greater than the deadband value, the DBEQUALS analog high / low comparison function block outputs a switch value of "1." When the absolute value of the difference between the two analog input signals is less than the absolute value of the difference between the deadband value and the return value, the DBEQUALS analog high / low comparison function block outputs a switch value of "0." If one of the input values ​​is an invalid real number, the output value is also invalid and its quality is set to BAD. If all input values ​​are valid, the output value is also valid, and the quality of the input value difference is passed to the output.

[0013] Furthermore, a quality type field can be selected in the QUALITYMON quality judgment function block. When the quality of the input value is the same as the selected quality type field, the QUALITYMON quality judgment function block outputs a switch signal "1"; when the quality of the input value is different from the selected quality type field, the QUALITYMON quality judgment function block outputs a switch signal "0".

[0014] Furthermore, the input data type of the HIGHMON high limit function block is analog, and the output type is switch. The HIGHMON high limit function block is set with a high limit value. When the input value is greater than the high limit value, the HIGHMON high limit function block outputs a switch value of "1", and when the input value is less than the high limit value, the HIGHMON high limit function block outputs a switch value of "0".

[0015] Furthermore, the FLIPFLOP function block has two switch inputs: a SET input and a RESET input, and a switch output. When the SET input is "1," the FLIPFLOP function block outputs "1," and when the RESET input is "1," the FLIPFLOP function block outputs "0."

[0016] Furthermore, the ONESHOT signal conversion function block has a switching input type and a switching output type. When the input changes from "0" to "1," the OUT output is enabled and time accumulation begins until the accumulated time equals the pulse time TARGET, at which point the OUT output stops. If the OUT output accumulated time does not reach the pulse time TARGET and the input changes from "0" to "1" again, the block starts counting from the last input change from "0" to "1" and continues outputting until the pulse time TARGET is reached.

[0017] Furthermore, the ONDELAY delay function block has a switch input type and a switch output type. When the input changes from "0" to "1," time accumulation begins. When the accumulated time equals TARGET, the OUT output is activated. When the input changes from "1" to "0," the OUT output ends.

[0018] The advantages of the present invention are that: by configuring a variety of DCS logic blocks, temperature measurement logic protection that prevents sudden changes in temperature measurement values ​​and can perform quality judgment is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of DCS configuration of the method of the present invention.

[0020] In the figure: 1. Analog temperature value; 2. TRANSPORT analog delay function block; 3. TRANSPORT analog high and low value comparison function block; 4. QUALITYMON quality judgment function block; 5. OR gate function block; 6. HIGHMON high limit function block; 7. NOT gate function block N1; 8. NOT gate function block N2; 9. NOT gate function block N3; 10. AND gate function block AND1; 11. ONESHOT signal conversion function block; 12. FLIPFLOP function block; 13. NOT gate function block N4; 14. ONDELAY delay function block; 15. AND gate function block AND2; 16. Temperature value sudden change alarm block; 17. Temperature measurement value sudden change protection function block. DETAILED DESCRIPTION

[0021] To facilitate a clear understanding of the technical solutions of the present invention by those skilled in the art, the present invention is further described below in conjunction with the accompanying drawings of the embodiments disclosed herein. The configuration structures of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are intended to explain the present invention and are not to be construed as limiting the present invention.

[0022] like Figure 1 The DCS configuration diagram shown in the figure is as follows:

[0023] Step 1: Build the TRANSPORT analog delay function block 2 and the DBEQUALS analog high and low value comparison function block 3 in the DCS system. The analog temperature value 1 is used as the input of the TRANSPORT analog delay function block 2. The delay value of the TRANSPORT analog delay function block 2 is 1. The output of the TRANSPORT analog delay function block 2 is used as an input of the DBEQUALS analog high and low value comparison function block 3. The analog temperature value 1 is used as the input of the DBEQUALS analog high and low value comparison function block. Another input of energy block 3, DBEQUALS analog high and low value comparison function block 3 compares the two input values ​​and obtains the output; the dead zone value of DBEQUALS analog high and low value comparison function block 3 is 3, and the return value is 0.2. When the absolute value of the difference between the two analog input signals is greater than the dead zone value, DBEQUALS analog high and low value comparison function block 3 outputs the switch value "1". When the absolute value of the difference between the two analog input signals is less than the absolute value of the difference between the dead zone value and the return value, DBEQUALS analog high and low value comparison function block 3 outputs the switch value "0".

[0024] Step 2: Build an OR gate function block 5 and a QUALITYMON quality judgment function block 4 in the DCS system. A quality type field, such as BAD, FAIR, Not GOOD, or GOOD, can be selected in the QUALITYMON quality judgment function block 4. The default is BAD. When the quality of the input value is the same as the selected quality type field, the QUALITYMON quality judgment function block 4 outputs a switch signal "1." When the quality of the input value is different from the selected quality type field, the QUALITYMON quality judgment function block 4 outputs a switch signal "0." In step 1, the analog temperature value 1 serves as the input of the QUALITYMON quality judgment function block 4, and the output of the QUALITYMON quality judgment function block 4 serves as one input of the function block 5. In step 1, the output of the DBEQUALS analog high and low value comparison function block 3 serves as another input of the OR gate function block 5.

[0025] Step 3: Build HIGHMON function block 6 and NOT function block N17 in the DCS system 、 NOT gate function block N39 and NOT gate function block N28, and AND gate function block AND110. For example, if the high limit value of the HIGHMON high limit function block 6 is 115, when the input value is greater than the high limit value, the HIGHMON high limit function block 6 outputs a switch value "1", and when the input value is less than the high limit value, the HIGHMON high limit function block 6 outputs a switch value "0"; in step 1, the analog temperature value 1 serves as the input of the HIGHMON high limit function block 6, the output of the HIGHMON high limit function block 6 serves as the input of the NOT gate function block N17, and the output of the NOT gate function block N17 serves as an input of the AND gate function block AND110; in step 1, the output of the DBEQUALS analog high and low value comparison function block 3 serves as the input of the NOT gate function block N28, and the output of the NOT gate function block N28 serves as an input of the AND gate function block AND110; in step 2, the output of the QUALITYMON quality judgment function block 4 serves as the input of the NOT gate function block N39, and the output of the NOT gate function block N39 serves as an input of the AND gate function block AND110.

[0026] Step 4: Build the FLIPFLOP function block 12 and the ONESHOT signal conversion function block 11 in the DCS system. The FLIPFLOP function block 12 has two switch inputs, SET and RESET. When the SET input is "1," the FLIPFLOP function block 12 outputs "1." When the RESET input is "1," the FLIPFLOP function block 12 outputs "0." The pulse time TARGET of the ONESHOT signal conversion function block 11 is 2. When the input transitions from "0" to "1," the OUT output is enabled and begins accumulating time until the accumulated time equals the pulse time TARGET, at which point the OUT output stops. If the OUT output accumulated time does not reach the pulse time TARGET and another input transitions from "0" to "1," the output will resume counting from the last input transition from "0" to "1" until the pulse time TARGET is reached. The output of the OR gate function block 5 in step 2 serves as the SET input of the FLIPFLOP function block 12. The output of the AND gate function block AND110 in step 3 serves as the input of the ONESHOT signal conversion function block 5. The output of the ONESHOT signal conversion function block 11 serves as the RESET input of the FLIPFLOP function block 12. The output of the FLIPFLOP function block 12 serves as the input of the temperature measurement value sudden change alarm function block 16.

[0027] Step 5: Build the ONDELAY delay function block 14, the AND gate function block AND215, and the NOT gate function block N413 in the DCS system. The accumulated time TARGET of the ONDELAY delay function block 14 is 3. When the input of the ONDELAY delay function block changes from "0" to "1", it starts to accumulate time until the accumulated time equals TARGET, and the OUT output is started. When the input changes from "1" to "0", the OUT output ends. In step 3, the output of the HIGHMON high limit function block 6 serves as the input of the ONDELAY delay function block 14, and the output of the ONDELAY delay function block 14 serves as the input of the AND gate function block AND213. In step 4, the output of the FLIPFLOP function block 12 serves as the input of the NOT gate function block N413, and the output of the NOT gate function block N413 serves as another input of the AND gate function block AND215. The output of the AND gate function block AND215 serves as the input of the temperature measurement value sudden change protection function block 17.

[0028] Example: Protection against sudden changes in temperature measurement values ​​during steam turbine operation

[0029] When the steam turbine is operating normally, when the temperature change of the turbine thrust bearing is greater than 3℃ / s or the quality of the turbine thrust bearing temperature is BAD, the FLIPFLOP function block 12 is activated and the turbine thrust bearing temperature mutation alarm 16 is activated; when the turbine thrust bearing temperature is lower than 115℃, the input of the HIGHMON high limit function block 6 in step 3 is lower than the high limit value, and the HIGHMON high limit function block 16 is not triggered. After 2 consecutive seconds, the FLIPFLOP function block 12 is reset and the turbine thrust bearing temperature mutation alarm 16 disappears.

[0030] The steam turbine operates normally. When the temperature of the turbine thrust bearing is lower than 115°C, the input of the HIGHMON high limit function block 6 in step 3 is lower than the high limit value, and the HIGHMON high limit function block 6 does not trigger the action. Subsequently, the thrust bearing high temperature protection trip output by the ONDELAY delay function block 14 and the AND gate function block AND110 does not operate.

[0031] During normal steam turbine operation, when the turbine thrust bearing temperature is no less than 115°C, the input of HIGHMON high-limit function block 6 in step 3 is no less than the high limit, triggering HIGHMON high-limit function block 6. If the continuous cumulative time of ONDELAY delay function block 14 is less than 3 seconds, ONDELAY delay function block 14 does not trigger, and the thrust bearing high temperature protection trip output by AND gate function block AND110 does not operate. If the continuous cumulative time of ONDELAY delay function block 14 reaches 3 seconds, ONDELAY delay function block 14 triggers, and one input of AND gate function block AND110 meets the conditions.

[0032] When the turbine is operating normally, when the temperature of the turbine thrust bearing is not lower than 115℃, and the temperature change is less than 3℃ / s and it is not a bad quality, it will trigger the ONESHOT signal conversion function block 11 to send a 2s pulse signal, which serves as the RESET input of the FLIPFLOP function block 12. After passing through the NOT gate function block N413, the other input of the AND gate function block AND110 meets the conditions.

[0033] From the above, it can be seen that when the thrust bearing temperature of a turbine that is not of poor quality is not lower than 115°C and the change in temperature value is less than 3°C / s, the thrust bearing high temperature protection tripping action will be triggered after 3s.

[0034] Although one embodiment of the present invention has been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system, characterized in that: Using DCS system configuration, the process and methods include: Step 1: Set up the TRANSPORT analog delay function block and the DBEQUALS analog high-low comparison function block in the DCS system. The analog temperature value serves as the input of the TRANSPORT analog delay function block, and the output of the TRANSPORT analog delay function block serves as one input of the DBEQUALS analog high-low comparison function block; the analog temperature value serves as the other input of the DBEQUALS analog high-low comparison function block. The DBEQUALS analog high-low comparison function block compares the two input values ​​and obtains an output. Step 2: Build an OR gate function block and a QUALITYMON quality judgment function block in the DCS system. The analog temperature value serves as the input of the QUALITYMON quality judgment function block, and the output of the QUALITYMON quality judgment function block serves as one input of the OR gate function block; the output of the DBEQUALS analog high and low value comparison function block serves as the other input of the OR gate function block; Step 3: Build a HIGHMON high limit function block, a NOT gate function block, and an AND gate function block AND1 in the DCS system. The NOT gate function block includes a NOT gate function block N1, a NOT gate function block N2, and a NOT gate function block N3. In step 1, the analog temperature value 1 serves as the input of the HIGHMON high limit function block 6, the output of the HIGHMON high limit function block serves as the input of the NOT gate function block N1, and the output of the NOT gate function block N1 serves as an input of the AND gate function block AND1; in step 1, the output of the DBEQUALS analog high and low value comparison function block 3 serves as the input of the NOT gate function block N2, and the output of the NOT gate function block N2 serves as an input of the AND gate function block AND1; in step 2, the output of the QUALITYMON quality judgment function block 4 serves as the input of the NOT gate function block N3, and the output of the NOT gate function block N3 serves as an input of the AND gate function block AND1; Step 4: Build the FLIPFLOP function block and the ONESHOT signal conversion function block in the DCS system. The output of the OR gate in step 2 serves as the SET input of the FLIPFLOP function block. The output of the AND gate function block AND1 in step 3 serves as the input of the ONESHOT signal conversion function block. The output of the ONESHOT signal conversion function block serves as the RESET input of the FLIPFLOP function block. The output of the FLIPFLOP function block serves as the input of the temperature measurement value sudden change alarm function block. Step 5: Build the ONDELAY delay function block, AND gate function block AND2, and NOT gate function block N4 in the DCS system. The output of the HIGHMON high limit function block in step 3 serves as the input of the ONDELAY delay function block, and the output of the ONDELAY delay function block serves as one input of the AND gate function block AND2. The output of the FLIPFLOP function block in step 4 serves as the input of the NOT gate function block N4, and the output of the NOT gate function block N4 serves as the other input of the AND gate function block A2. The output of the AND gate function block A2 serves as the input of the temperature measurement value sudden change protection function block.

2. The protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system according to claim 1, characterized in that: The input value and output value of the TRANSPORT analog delay function block are consistent. By setting the delay time, the TRANSPORT analog delay function block has a delay function and will output the value after the delay time.

3. The protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system according to claim 1, characterized in that: The DBEQUALS analog high / low comparison function block has two analog inputs and a switch output. When the absolute value of the difference between the two analog input signals is greater than the deadband value, the DBEQUALS analog high / low comparison function block 3 outputs a switch value of "1." When the absolute value of the difference between the two analog input signals is less than the absolute value of the difference between the deadband value and the return value, the DBEQUALS analog high / low comparison function block outputs a switch value of "0." 4. The protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system according to claim 1, characterized in that: A quality type field can be selected in the QUALITYMON quality judgment function block. When the quality of the input value is the same as the selected quality type field, the QUALITYMON quality judgment function block outputs a switch signal "1"; when the quality of the input value is different from the selected quality type field, the QUALITYMON quality judgment function block outputs a switch signal "0".

5. The protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system according to claim 1, characterized in that: The HIGHMON function block has an analog input and a digital output. It has a high limit. When the input value is greater than the high limit, the block outputs a "1"; when the input value is less than the high limit, the block outputs a "0." 6. The protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system according to claim 1, characterized in that: The FLIPFLOP function block has two switch inputs: a SET input and a RESET input. Its output is also a switch. When the SET input is "1," the FLIPFLOP function block outputs a "1." When the RESET input is "1," the FLIPFLOP function block outputs a "0." 7. The protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system according to claim 1, characterized in that: The ONESHOT signal conversion function block has a switch input and a switch output. When the input changes from "0" to "1", the OUT output is enabled and time accumulation begins. When the accumulated time equals the pulse time TARGET, the OUT output stops. When the OUT output cumulative time does not reach the pulse time TARGET, and an input quantity changes from "0" to "1", it will be calculated from the time when the last input quantity changes from "0" to "1" and continue to output until the pulse time TARGET.

8. The protection method for preventing sudden changes in temperature measurement values ​​based on a DCS system according to claim 1, characterized in that: The ONDELAY function block has a switch input and a switch output. When the input transitions from "0" to "1," it begins accumulating time until the accumulated time reaches TARGET, at which point the OUT output is activated. When the input transitions from "1" to "0," the OUT output ends.

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