Fire detection method based on two-parameter molded line type flame sensor

Abstract

The invention discloses a fire detection method based on a two-parameter molded line type flame sensor. The method comprises the following steps: 1) carrying out temperature calibration on the two-parameter molded line type flame sensor; 2) collecting capacitance and resistance parameter values of the flame sensor, and transmitting the parameter values to a signal processing module; and 3) the signal processing module processes the collected parameter values, judges the parameter values through a multi-layer logic control algorithm, and outputs an alarm signal or other preset type signals according to a judgment result. Parameter setting of the flame sensor is adjusted according to multiple experimental data, and the problems that a linear flame sensor is low in sensitivity and slow in fire response speed are solved. And an optimization design scheme of software system structure optimization, data structure optimization and algorithm optimization is provided, so that the memory access speed is higher, the data transmission performance and the system reliability are improved, and the false alarm prevention performance of the device is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of fire detection, and in particular to a fire detection method based on a dual-parameter linear flame sensor. Background Art

[0002] A fire detection device is a device used to detect flames and issue an alarm warning. It can monitor fires and carry out fire linkage at the same time, so that the fire situation can be controlled in a timely and effective manner.

[0003] At present, there are three types of linear flame sensors: resistance type, thermocouple type, flexible shell type, dual parameter type, and fiber Bragg grating type. The dual parameter linear flame sensor is highly sensitive to flames and is mainly used to ensure the safe operation of key equipment such as coal chemical gasification furnaces, thermal power air preheaters, polysilicon ingot furnaces, and vehicle power compartments. It is suitable for a variety of fire detection scenarios and has broad application prospects. However, since most of the places where linear flame sensors are used are in harsh environmental conditions, the current linear flame sensors have low sensitivity for fire detection, slow fire alarm response speed, poor anti-interference ability, and are prone to false fire alarms. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a fire detection method based on a dual-parameter linear flame sensor to solve the problems of low sensitivity, slow fire alarm response speed, poor anti-interference ability and easy false fire alarm in the prior art linear flame sensor for fire detection.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a fire detection method based on a dual-parameter linear flame sensor comprises the following steps: 1) Temperature calibration of dual-parameter linear flame sensor; 2) Collect the capacitance and resistance parameter values ​​of the flame sensor and transmit the parameter values ​​to the signal processing module; 3) The signal processing module processes the collected parameter values, judges the parameter values ​​through a multi-layer logic control algorithm, and outputs an alarm signal or other preset type of signal based on the judgment result; Wherein, the multi-layer logic control algorithm includes: 301) using a difference comparison method to compare the acquired parameter value with the normal value range of the flame sensor, and when the difference exceeds a preset value, obtaining a first state flag; 302) extracting the parameter values ​​collected within a preset continuous time period and calculating the change slope of the parameter value, and when the change rate of the slope exceeds a preset value, obtaining a second state flag; 303) Performing a fuzzy logic “AND” operation on the input variable data value to obtain the output variable membership degree, and when the membership degree exceeds a preset value, obtaining a third state flag; 304) If within a preset time, the first state flag, the second state flag, and the third state flag simultaneously meet preset conditions, an alarm signal is output, otherwise other preset type signals are output.

[0006] As an optimization, the temperature calibration of the flame sensor in step 1 includes collecting the experimental values ​​of resistance and capacitance of the sensor at a preset temperature rise rate within a preset temperature range, fitting the nonlinear characteristics of the sensor parameters, and using a software temperature compensation algorithm. Specifically, according to the experimental values, a least squares fitting method is used to calculate at least N+1 data points, and N+1 polynomial fitting is performed to obtain the polynomial coefficient Ai (t), and then at least M+1 coefficients at different temperatures are calculated, and M+1 polynomial fitting is performed. A total of at least N+M+2 polynomial fittings are performed to obtain the coefficient Ai (t) at different temperatures, and the measured value after temperature compensation is obtained to calibrate the parameter value of the flame sensor.

[0007] As an optimization, the preset temperature rise rate is 2°C / min, and the preset temperature range is -50°C-+500°C.

[0008] As an optimization, in step 303, when the degree of membership is greater than 0.5, a third state flag is obtained.

[0009] As an optimization, in step 304, the other preset type signals include normal, overheat, fault, short circuit or open circuit.

[0010] Compared with the prior art, the present invention has the following advantages: The present invention adjusts the parameter settings of the flame sensor according to multiple experimental data, solving the problem of low sensitivity and slow fire alarm response speed of the linear flame sensor. The phase-locked loop technology is adopted, and the reference signal input from the outside of the control circuit is used to control the frequency and phase of the oscillation signal inside the loop, so as to realize the automatic tracking of the output signal frequency to the input signal frequency, so that the frequency and phase of the controlled oscillator maintain a certain relationship, which greatly improves the anti-interference ability of the product. The optimization design scheme of software architecture optimization, data structure optimization and algorithm optimization is proposed, so that the memory access speed is faster, the data transmission performance and system reliability are improved, and the anti-false alarm performance of the device is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a principle block diagram of the present invention. DETAILED DESCRIPTION

[0012] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0013] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0015] Example: See Figure 1The fire detection device for realizing the fire detection method of the present invention is mainly composed of a signal processing module and a linear flame sensor (hereinafter referred to as the sensor), wherein the hardware part of the signal processing module includes an FPGA main control core, an external Flash, an A / D analog-to-digital conversion chip, an analog signal sampling circuit, an optical coupling isolation circuit, a power conversion circuit, an RS485 serial port circuit and a drive alarm circuit. The power conversion circuit converts DC24V to 5V, then 5V to 3.3V, and 3.3V to 1.2V to supply other chips for operation.

[0016] The temperature sensitive part of the sensor is a coaxial cable. The core wire and the outer tube are the positive and negative electrodes of the element respectively. In between is a dense sensitive dielectric material with a positive dielectric temperature coefficient and a negative resistance temperature coefficient. When a flame approaches the sensor, the radiant heat energy of the flame will be absorbed by the sensor, causing the sensor temperature to rise. At the same time, the light radiation of the flame will also be sensed by the sensor. The change in temperature causes the equivalent resistance and capacitance between the sensor core wire and the outer tube to change. The higher the temperature, the smaller the resistance value and the larger the capacitance value. After a series of data processing, the signal processing module outputs an alarm signal.

[0017] The present invention provides a fire detection method based on a dual-parameter linear flame sensor, comprising the following steps: 1) Perform temperature calibration on the dual-parameter linear flame sensor.

[0018] Specifically, the temperature calibration of the flame sensor includes collecting the resistance and capacitance experimental values ​​of the sensor in the temperature range of -50℃-+500℃ with a temperature rise rate of no more than 2℃ / min, fitting the nonlinear characteristics of the sensor parameters, and using the software temperature compensation algorithm. Specifically, according to the experimental values, the least squares fitting method is used to calculate at least N+1 data points, and N+1 polynomial fitting is performed to obtain the polynomial coefficient Ai(t), Ai(t) is an N-order polynomial function, and then at least M+1 coefficients at different temperatures are calculated, and M+1 polynomial fitting is performed. In total, at least N+M+2 polynomial fittings are performed to obtain the coefficient Ai(t) at different temperatures, and the temperature-compensated measurement values ​​are obtained to calibrate the parameter values ​​of the flame sensor. After compensation, the capacitance deviation is ≤±5%; the resistance deviation is lnR≤±10% (R is in ohms). The compensation measurement value has higher accuracy, which improves the reliability of data collection.

[0019] 2) Collecting the capacitance and resistance parameter values ​​of the flame sensor and transmitting the parameter values ​​to the signal processing module. In this embodiment, a multi-point average sampling algorithm is used to collect the resistance and capacitance data values.

[0020] 3) The signal processing module processes the collected parameter values, judges the parameter values ​​through a multi-layer logic control algorithm, and outputs an alarm signal or other preset type of signal based on the judgment result; Wherein, the multi-layer logic control algorithm includes: 301) Using the difference comparison method, the size of the collected parameter value is compared with the normal value range of the flame sensor. If the absolute value of the difference with the normal value is greater than S, a preliminary judgment of fire or non-fire is made, and the first state flag Q1 is obtained; 302) extracting N parameter values ​​collected within a continuous time of every 200ms, and calculating the change slope of the parameter value. When the change rate of the slope exceeds K, it is determined that an abnormal situation such as fire or overheating may occur within the continuous time, and a second state flag Q2 is obtained; 303) Performing a fuzzy logic “AND” operation on the input variable data value to obtain the output variable membership u. When the membership exceeds 0.5, a third state flag Q3 is obtained; 304) If the status flags Q1>0&&Q2>0&&Q3>0 are met at the same time within a time period of less than 5 seconds, it is judged as a fire alarm, and the alarm warning is delayed for ≥10 seconds and the fire extinguishing device is controlled to start. Otherwise, other preset status warnings such as normal, overheating, fault, short circuit, open circuit, etc. are reported.

[0021] In summary, the present invention adjusts the parameter settings of the flame sensor according to multiple experimental data, solving the problem of low sensitivity and slow fire alarm response speed of the linear flame sensor. The phase-locked loop technology is adopted, and the reference signal input from the outside of the control circuit is used to control the frequency and phase of the oscillation signal inside the loop, so as to realize the automatic tracking of the output signal frequency to the input signal frequency, so that the frequency and phase of the controlled oscillator maintain a certain relationship, which greatly improves the anti-interference ability of the product. The optimization design scheme of software architecture optimization, data structure optimization and algorithm optimization is proposed, which makes the memory access speed faster, improves the data transmission performance and system reliability, and greatly improves the anti-false alarm performance of the device.

[0022] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A fire detection method based on a dual-parameter linear flame sensor, characterized in that: The following steps are included: 1) Temperature calibration of dual-parameter linear flame sensor; 2) Collect the capacitance and resistance parameter values ​​of the flame sensor and transmit the parameter values ​​to the signal processing module; 3) The signal processing module processes the collected parameter values, judges the parameter values ​​through a multi-layer logic control algorithm, and outputs an alarm signal or other preset type of signal based on the judgment result; Wherein, the multi-layer logic control algorithm includes: 301) using a difference comparison method to compare the acquired parameter value with the normal value range of the flame sensor, and when the difference exceeds a preset value, obtaining a first state flag; 302) extracting the parameter values ​​collected within a preset continuous time period and calculating the change slope of the parameter value, and when the change rate of the slope exceeds a preset value, obtaining a second state flag; 303) Performing fuzzy logic "AND" operation on the input variable data value to obtain the output variable membership degree, and when the membership degree exceeds the preset value, obtaining the third state flag; 304) If within a preset time, the first state flag, the second state flag, and the third state flag simultaneously meet preset conditions, an alarm signal is output, otherwise other preset type signals are output.

2. A fire detection method based on a dual-parameter linear flame sensor according to claim 1, characterized in that: The temperature calibration of the flame sensor in step 1 includes collecting the experimental values ​​of resistance and capacitance of the sensor at a preset temperature rise rate within a preset temperature range, fitting the nonlinear characteristics of the sensor parameters, and specifically, using a software temperature compensation algorithm, using a least squares fitting method according to the experimental values, calculating at least N+1 data points, performing N+1 polynomial fitting, obtaining the polynomial coefficient Ai(t), and then calculating at least M+1 coefficients at different temperatures, performing M+1 polynomial fitting, and performing at least N+M+2 polynomial fittings in total to obtain the coefficient Ai(t) at different temperatures, and obtaining the temperature compensated measurement value to calibrate the parameter value of the flame sensor.

3. A fire detection method based on a dual-parameter linear flame sensor according to claim 2, characterized in that: The preset temperature rise rate is 2°C / min, and the preset temperature range is -50°C-+500°C.

4. A fire detection method based on a dual-parameter linear flame sensor according to claim 1, characterized in that: In step 303, when the degree of membership is greater than 0.5, a third state flag is obtained.

5. A fire detection method based on a dual-parameter linear flame sensor according to claim 1, characterized in that: In step 304, the other preset type signals include normal, overheat, fault, short circuit or open circuit.

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