Sensor signal acquisition circuit for steam turbine monitoring protection instrument
By designing a sensor signal acquisition circuit containing multiple signal processing loops, the problems of insufficient accuracy and high noise in the prior art are solved, and high-precision acquisition of signals in a wide range is achieved to meet the measurement needs of different types of sensor signals.
Patent Information
- Application Number
- CN202411256683.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-09
- Publication Date
- 2024-12-13
AI Technical Summary
The sensor signal acquisition circuit of existing turbine monitoring and protection instruments has problems such as insufficient accuracy, high noise, and signal distortion when processing AC and DC signals, which is difficult to adapt to the measurement requirements of output signals of different types of sensors, and has insufficient signal processing capabilities.
A sensor signal acquisition circuit including signal interface, DC component processing circuit and AC component processing circuit is designed, using amplification and A/D adapter circuit, digital low pass circuit, D/A conversion and amplification circuit, and digital band pass circuit. , frequency signal processing loops, etc., through processing technologies such as amplification, filtering, A/D and D/A conversion, digital filtering, etc., to ensure high accuracy and low noise of the signal.
It realizes high-precision acquisition of signals in a wide range (-22~0~+22VDC, 0~6Vrms, 0~50KHz) with an accuracy of ±0.1%, reducing noise, enhancing small signal processing capabilities, and adapting to different types of sensors signal measurement requirements.
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Figure CN119122633A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of turbine supervisory instruments (TSI instruments for short), and in particular to a sensor signal acquisition circuit for a turbine supervisory instrument. Background Art
[0002] The general usage of turbine supervisory instruments (TSI instruments) is as follows: TSI instruments are one of the key devices to ensure the safe operation of rotating machinery. TSI instruments need to monitor and protect many types of parameter signals. Commonly used physical parameters include: vibration, axial displacement, expansion difference, eccentricity, speed, cylinder expansion, stroke, etc. In order to monitor and measure these parameters, it is necessary to convert the physical parameters into "physical quantity / electric quantity", that is, to use sensors to convert physical parameters into electrical parameters. Different types of sensors need to be selected according to different physical parameters. Different types of sensors will output electrical signals in different forms. Electrical signals are divided into: alternating current signals (AC), direct current signals (DC), and current signals (I), and their signal characteristics are described by the frequency and amplitude of the signal.
[0003] Characteristics of the sensors used for the physical parameters of TSI instruments and the corresponding output electrical signals: 1. The sensor types used for vibration parameters are: eddy current sensor, magnetoelectric sensor, piezoelectric sensor. The corresponding output signal characteristics are described by mathematical formulas: -DC+AC; 0V+AC; +DC+AC.
[0004] 2. The sensor types used for axial displacement and differential expansion parameters are: eddy current sensor and DC LVDT sensor. The corresponding output signal characteristics are described by mathematical formula: DC.
[0005] 3. The sensor type used for the eccentricity parameter is an eddy current sensor. The corresponding output signal characteristics are described by the mathematical formula: -DC+AC.
[0006] 4. The sensor types used for the speed parameter are: eddy current sensor, magnetoresistive sensor, Hall sensor. The corresponding output signal characteristics are described by mathematical formulas: -DC+AC; 0V+AC; +DC+AC.
[0007] 5. The sensor type used for cylinder expansion and stroke parameters is: current type LVDT sensor. The corresponding output signal characteristic is the current signal (I). Usually, when processing in electronic circuits, the current signal is converted into a voltage signal for processing, which is described by the mathematical formula: DC.
[0008] After classifying the above electrical signals, the following conclusions are drawn: the sensor output signals that the monitor system of the TSI instrument needs to process are: alternating current signal (AC), direct current signal (DC), and frequency signal. Among them, the alternating current signal (AC) has an amplitude range of 0 to 6Vrms, the frequency signal has an amplitude range of 0 to 50KHz, and the direct current signal (DC) has an amplitude range of -22 to 0 to +22VDC. The existing technology on the market now usually designs different physical parameters of the TSI instrument into monitors, such as vibration parameters designed as vibration monitors, axial displacement parameters designed as axial displacement monitors, etc., so it is relatively easy to design the sensor signal acquisition circuit, because the sensor signals input by the monitors of different parameters are relatively simple, but the types and varieties of monitors are too many, which is not convenient for reducing costs. There are also many engineers and technicians from professional manufacturers in the market who have tried to design a universal sensor signal acquisition circuit to meet the requirements of processing output signals of different types of sensors. However, when processing AC (alternating current) and DC (direct current) signals, the sensor signal acquisition circuit usually has problems such as insufficient accuracy, high noise, and signal distortion, which may lead to inaccurate monitoring data. Most of the current sensor signal acquisition circuits have the following shortcomings: 1. Noise is easily introduced during AC signal processing, affecting the measurement accuracy of the sensor output signal.
[0009] 2. The stability and accuracy of DC signal processing are insufficient and it is easily affected by external interference. Since the input signal range that needs to be collected by DC signals is very large (±22VDC), it is difficult to balance stability and measurement accuracy.
[0010] 3. The bias and gain adjustments are not flexible enough to meet the measurement requirements of different types of sensor output signals.
[0011] 4. Insufficient small signal processing capability, especially for piezoelectric sensors, whose output signal is a millivolt-level AC signal superimposed on +12VDC, which cannot effectively amplify and filter out noise. Summary of the invention
[0012] According to an embodiment of the present invention, a sensor signal acquisition circuit for a steam turbine monitoring and protection instrument is provided, comprising: A signal interface, which is used to receive output signals from external sensors and input signals; A DC component processing circuit, the DC component processing circuit is connected to the signal interface and is used to process the input signal; An AC component processing circuit, the AC component processing circuit is connected to the signal interface and is used to process the input signal; The CPU system is connected to a DC component processing circuit and an AC component processing circuit, and is used to calculate the DC component and the AC component of the input signal.
[0013] Furthermore, the DC component processing circuit includes: An amplification and A / D conversion circuit, the amplification and A / D conversion circuit is connected to the signal interface and is used to amplify and A / D convert the input signal; The digital low-pass circuit is connected with the amplification and A / D conversion circuit and the CPU system, and is used for performing digital low-pass filtering on the signal processed by the amplification and A / D conversion circuit.
[0014] Furthermore, the amplification and A / D conversion circuit includes: A first signal amplifier, connected to the signal interface and used to amplify the input signal; The first A / D converter is connected to the first signal amplifier and the digital low-pass loop, and is used for performing A / D conversion on the signal amplified by the first signal amplifier.
[0015] Furthermore, the AC component processing circuit includes: A D / A conversion and amplification circuit, the D / A conversion and amplification circuit is connected to the CPU system and is used to perform D / A conversion and amplification on the DC component signal calculated by the CPU system; A subtractor, which is connected to the D / A conversion and amplification circuit and the signal interface, and is used to eliminate the DC component in the input signal; PGA, PGA is connected to the subtractor and is used to amplify the signal processed by the subtractor; A second A / D converter, the second A / D converter is connected to the PGA and is used to perform A / D conversion on the signal amplified by the PGA; The digital bandpass loop is connected to the second A / D converter and the CPU system and is used for digital bandpass filtering.
[0016] Furthermore, the D / A conversion and amplification circuit includes: D / A converter, the D / A converter is connected to the CPU system and is used for D / A conversion; The second amplifier is connected with the D / A converter and the subtractor for amplification.
[0017] Furthermore, it also includes: a frequency signal processing circuit, which is connected to the PGA and CPU system and is used to regularize the signal into a standard pulse signal.
[0018] Furthermore, the frequency signal processing circuit includes: Schmitt trigger, the Schmitt trigger is connected to the PGA; A signal conditioning circuit is connected to the Schmitt trigger and the CPU system.
[0019] According to a sensor signal acquisition circuit for a steam turbine monitoring and protection instrument according to an embodiment of the present invention, a high-precision, low-noise sensor signal acquisition circuit for a steam turbine technical protection instrument is designed, which can more effectively analyze and process various types of sensor signals, changing the traditional sensor signal acquisition circuit specially designed according to a certain sensor type. It takes into account a wide range of DC (-22~0~+22VDC), AC (0~6Vrms), and frequency (0~50KHz) input range signals, and the AC and DC signals are superimposed on each other, meeting the acquisition accuracy of the entire measurement range: ±0.1%.
[0020] It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the technology as claimed. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 The present invention provides an overall framework of a sensor signal acquisition circuit for a steam turbine monitoring and protection instrument according to an embodiment of the present invention. DETAILED DESCRIPTION
[0022] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings to further illustrate the present invention.
[0023] First, combine Figure 1 A sensor signal acquisition circuit for a steam turbine monitoring and protection instrument according to an embodiment of the present invention is described, which is used for collecting high-precision, multi-type sensor signals, and simultaneously accurately measures and calculates three characteristic parameters of the input signal, such as DC voltage, AC voltage, and signal frequency, and has a wide range of application scenarios.
[0024] like Figure 1 As shown, a sensor signal acquisition circuit for a steam turbine monitoring and protection instrument according to an embodiment of the present invention comprises a signal interface 1, a DC component processing circuit, an AC component processing circuit and a CPU system 4.
[0025] Specifically, Figure 1 As shown, the signal interface 1 is used to receive the output signal of the external sensor and input the signal, and divide the input signal into two paths for signal processing, one path for processing the DC component and the other path for processing the AC component.
[0026] Specifically, Figure 1As shown, the DC component processing circuit is connected to the signal interface 1 and is used to process the input signal. The DC component processing circuit includes: an amplification and A / D conversion circuit 21 and a digital low-pass circuit 22. The amplification and A / D conversion circuit 21 is connected to the signal interface 1 and is used to amplify and A / D convert the input signal; the digital low-pass circuit 22 is connected to the amplification and A / D conversion circuit 21 and the CPU system 4 and is used to perform digital low-pass filtering on the signal processed by the amplification and A / D conversion circuit 21. The signal interface 1 connects the input signal to the amplification and A / D conversion circuit 21 and the digital low-pass circuit 22, amplifies and regularizes the input signal, and performs A / D conversion to convert the analog signal into a digital signal. The digital signal is then processed by a digital low-pass filter to filter out high-frequency interference clutter to ensure the stability of the DC signal. Finally, it is received by the CPU system 4, and after quantization processing, the DC component of the input signal is calculated. For receiving eddy current displacement sensor, voltage type and current type LVDT sensor signals, when used as monitor types such as axial displacement, differential expansion, cylinder expansion, stroke, etc., a DC component processing circuit is used. The input signal range of the DC component processing circuit is: -22~0~+22VDC, and the measurement accuracy is: ±0.1% (full scale).
[0027] Further, if Figure 1 As shown, the amplification and A / D conversion circuit 21 includes: a first signal amplifier and a first A / D converter. The first signal amplifier is connected to the signal interface 1 and is used to amplify the input signal; the first A / D converter is connected to the first signal amplifier and the digital low-pass circuit 22 and is used to perform A / D conversion on the signal amplified by the first signal amplifier.
[0028] Specifically, Figure 1As shown, the AC component processing circuit is connected to the signal interface 1 and is used to process the input signal. The AC component processing circuit includes: a D / A conversion and amplification circuit 31, a subtractor 32, a PGA33, a second A / D converter 34 and a digital bandpass circuit 35. The D / A conversion and amplification circuit 31 is connected to the CPU system 4 and is used to perform D / A conversion and amplification on the DC component signal calculated by the CPU system 4; the subtractor 32 is connected to the D / A conversion and amplification circuit 31 and the signal interface 1 and is used to eliminate the DC component in the input signal; the PGA33 is connected to the subtractor 32 and is used to amplify the signal processed by the subtractor 32; the second A / D converter 34 is connected to the PGA33 and is used to perform A / D conversion on the signal amplified by the PGA33; the digital bandpass circuit 35 is connected to the second A / D converter 34 and the CPU system 4 and is used to perform digital bandpass filtering processing. The input signal taken from the sensor signal output, the DC component (digital quantity) measured by the DC component processing circuit and the CPU system 4, is converted into an analog signal through the D / A conversion and amplification circuit 31, and then amplified and regularized, adjusted to a suitable analog signal, and input to the subtractor 32 at the same time as the original input signal. To eliminate the DC component in the original input signal. The bias setting output by the CPU system 4 is dynamically adjusted according to the residual DC component in the AC channel. In this way, even if the DC component in the input signal drifts, the system can still stably and accurately measure the AC component and frequency signal. The AC signal in the sensor output has a large difference in amplitude depending on the type of sensor used. For some sensors, such as piezoelectric sensors, the signal characteristic is that a smaller AC signal is superimposed on the basis of +12VDC DC, and the effective value of the AC signal is almost in the order of millivolts; while for some sensors, such as eddy current sensors, the signal characteristic is that a larger AC signal is superimposed on the basis of -10VDC DC, and the effective value of the AC signal is almost in the order of several volts. The difference between the two is about 1000 times. For this purpose, a gain control module, namely PGA33 (programmable gain amplifier), is required. The amplifier gain can be programmed according to the amplitude of the input signal to accurately amplify the signal and meet the amplification requirements of different signal amplitudes. PGA33 (programmable gain amplifier) uses a high-precision programmable instrument amplifier. This amplifier has low offset voltage, close to zero offset and gain drift, extremely low 1 / f noise, and a digitally controllable gain range of 1 / 8~1024. Due to the use of a high-precision low-noise amplifier and noise filtering technology, the processing capability of weak signals is enhanced.The AC signal processed by various methods is sent to the second A / D converter 34 for A / D conversion, and the analog signal is converted into a digital signal. The digital signal is filtered by digital bandpass to filter out high-frequency interference and clutter and low-frequency beat signals generated during the digital processing process to ensure the stability of the AC signal. The digital signal is received by the CPU system 4, and after quantization processing, the AC component of the input signal is calculated. When receiving eddy current sensor, magnetoelectric sensor and piezoelectric sensor signals and used as vibration, eccentricity and other monitor types, the AC component processing circuit is used. The input signal range of the AC component processing circuit is: 0~6Vrms, and the measurement accuracy is: ±0.1% (full range).
[0029] Furthermore, in this embodiment, the D / A conversion and amplification circuit 31 includes: a D / A converter and a second amplifier. The D / A converter is connected to the CPU system 4 for performing D / A conversion; the second amplifier is connected to the D / A converter and the subtractor 32 for amplification.
[0030] Specifically, Figure 1 As shown, the CPU system 4 is connected to a DC component processing circuit and an AC component processing circuit, and is used to calculate the DC component and AC component of the input signal.
[0031] Further, if Figure 1 As shown, a sensor signal acquisition circuit for a steam turbine monitoring and protection instrument in an embodiment of the present invention further includes: a frequency signal processing circuit, which is connected to PGA33 and CPU system 4 and is used to regularize the signal into a standard pulse signal. The frequency signal processing circuit includes: a Schmitt trigger 51 and a signal regularization circuit 52. The Schmitt trigger 51 is connected to PGA33; the signal regularization circuit 52 is connected to the Schmitt trigger 51 and the CPU system 4. The output signal taken from the PGA33 (programmable gain amplifier) is shaped into a pulse signal by the Schmitt trigger 51, and output to the signal regularization circuit, and the pulse signal is modulated into a pulse signal matching the CPU system 4. The CPU system 4 receives the pulse signal, performs quantization processing, and calculates the frequency of the input AC signal. For receiving eddy current sensor, magnetoresistive sensor and Hall sensor signals, when used as a speed, key phase and other monitor types, the frequency signal processing circuit is used, and the input signal range of the frequency signal processing circuit is: 0~50KHz, and the measurement accuracy is: ±0.1% (full scale).
[0032] Working principle: The original output signal of the sensor is input to the signal interface 1, and then the input signal is divided into two paths for signal processing, one of which processes the DC component and the other processes the AC component.
[0033] DC component processing: One of the input signals is adjusted to the optimal value of the first A / D converter input by the first amplifier, and then output to the first A / D converter for analog-to-digital conversion. The standardized analog signal is converted into the original digital quantity, and then digital low-pass filtered and output to the CPU system 4. The DC component of the input signal is calculated by the CPU system 4.
[0034] AC component processing: The DC component signal calculated by the CPU system 4 is D / A converted, amplified and regularized, and then input to the subtractor 32 together with another input signal to eliminate the DC component in the input signal. The signal after the subtractor 32 passes through the PGA33 (programmable gain amplifier) to achieve accurate signal amplification to meet the amplification requirements of different signal amplitudes. After the signal is adjusted to the optimal value input by the second A / D converter 34, it is input to the second A / D converter 34 for A / D conversion, converting the standardized analog signal into the original digital quantity, and then performing digital bandpass filtering processing, and inputting it to the CPU system 4, and the AC component of the input signal is obtained after calculation.
[0035] Frequency signal processing: The input signal passes through the subtractor 32, and the AC signal with the DC component eliminated passes through the PGA33 (programmable gain amplifier), and then is input into the Schmitt trigger 51 and the signal conditioning circuit 52, which condition the signal into a standard pulse signal and input it into the counter of the CPU system 4. After calculation, the frequency of the input signal is obtained. The frequency measurement function is added to ensure the accurate acquisition and processing of the frequency signal.
[0036] Above, refer to Figure 1 A sensor signal acquisition circuit for a steam turbine monitoring and protection instrument according to an embodiment of the present invention is described. A high-precision, low-noise sensor signal acquisition circuit for a steam turbine technical protection instrument is designed, which can more effectively analyze and process various types of sensor signals, changing the traditional sensor signal acquisition circuit designed specifically for a certain sensor type. It takes into account a wide range of DC (-22~0~+22VDC), AC (0~6Vrms), and frequency (0~50KHz) input range signals, and the AC and DC signals are superimposed on each other, meeting the acquisition accuracy of the entire measurement range: ±0.1%.
[0037] It should be noted that, in this specification, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprises..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.
[0038] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.
Claims
1. A sensor signal acquisition circuit for a steam turbine monitoring and protection instrument, characterized in that: Include: A signal interface, the signal interface is used to receive output signals of external sensors and input signals; A DC component processing circuit, the DC component processing circuit is connected to the signal interface and is used to process the input signal; An AC component processing circuit, the AC component processing circuit is connected to the signal interface and is used to process the input signal; A CPU system, the CPU system is connected to the DC component processing circuit and the AC component processing circuit, and is used to calculate the DC component and the AC component of the input signal; The DC component processing circuit comprises: an amplification and A / D conversion circuit, the amplification and A / D conversion circuit being connected to the signal interface and used for amplifying and A / D converting the input signal; A digital low-pass circuit, which is connected to the amplification and A / D conversion circuit and the CPU system, and is used for performing digital low-pass filtering on the signal processed by the amplification and A / D conversion circuit; The AC component processing circuit comprises: A D / A conversion and amplification circuit, the D / A conversion and amplification circuit is connected to the CPU system and is used to perform D / A conversion and amplification on the DC component signal calculated by the CPU system; A subtractor, the subtractor is connected to the D / A conversion and amplification circuit and the signal interface, and is used to eliminate a DC component in an input signal; PGA, the PGA is connected to the subtractor and is used to amplify the signal processed by the subtractor; a second A / D converter, the second A / D converter being connected to the PGA and configured to perform A / D conversion on the signal amplified by the PGA; A digital bandpass loop is connected to the second A / D converter and the CPU system and is used for performing digital bandpass filtering.
2. The sensor signal acquisition circuit for a steam turbine monitoring and protection instrument as claimed in claim 1, characterized in that: The amplification and A / D conversion circuit comprises: A first signal amplifier, connected to the signal interface and used to amplify an input signal; A first A / D converter is connected to the first signal amplifier and the digital low-pass loop, and is used for performing A / D conversion on the signal amplified by the first signal amplifier.
3. The sensor signal acquisition circuit for a steam turbine monitoring and protection instrument as claimed in claim 1, characterized in that: The D / A conversion and amplification circuit comprises: A D / A converter, the D / A converter is connected to the CPU system and is used for performing D / A conversion; A second amplifier is connected to the D / A converter and the subtractor for amplification.
4. The sensor signal acquisition circuit for a steam turbine monitoring and protection instrument as claimed in claim 1, characterized in that: It also includes: a frequency signal processing circuit, which is connected to the PGA and the CPU system and is used to regularize the signal into a standard pulse signal.
5. The sensor signal acquisition circuit for a steam turbine monitoring and protection instrument as claimed in claim 4, characterized in that: The frequency signal processing circuit comprises: A Schmitt trigger connected to the PGA; A signal conditioning circuit is connected to the Schmitt trigger and the CPU system.