CN113551792A - Anti-interference capability improving method for PLC temperature module - Google Patents
Anti-interference capability improving method for PLC temperature module Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
- G01K1/20—Compensating for effects of temperature changes other than those to be measured, e.g. changes in ambient temperature
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Abstract
The invention discloses an anti-interference capability improving method for a PLC temperature module, which comprises the steps of collecting a temperature signal A by using a resistance temperature detector; designing a filter based on a Gaussian low-pass filter, and optimizing the filter by combining a Chebyshev function; removing sine wave interference in the temperature signal by using the optimized filter to obtain a temperature signal B; filtering the low-frequency signal in the temperature signal B through an F-P filter; according to the invention, the anti-interference capability of the PLC temperature acquisition module is improved by optimizing the resistance temperature detector and the filter, and the improved PLC temperature acquisition module has the advantages of wide measurement range, strong practicability, high precision and high reliability.
Description
Technical Field
The invention relates to the technical field of signal filtering, in particular to an anti-interference capability improving method for a PLC temperature module.
Background
The thermal resistor is generally applied to temperature measurement in medium and low temperature areas in industrial production, thermal resistors made of different materials correspond to different temperature measurement ranges, and most of temperature acquisition modules adopted on site adopt three-wire Pt100 temperature measurement resistor signals. However, when the grid-connected operation of the unit is close to the maximum power generation power, the irregular jumping of a plurality of stator windings and main transformer oil temperature measuring points of the unit is found, jumping measuring point channels are respectively arranged in different temperature measuring modules of different disk cabinets, the jumping amplitude and the jumping frequency are increased along with the increase of the load of the unit, and the jumping phenomenon disappears after the unit is disconnected. Meanwhile, interference exists on an external connection line of a channel which is not jumped, and basic noise is irregular and is accompanied by accidental pulse interference.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The present invention has been made in view of the above-mentioned conventional problems.
Therefore, the invention provides a method for improving the anti-interference capability of a PLC temperature module, which can solve the problem of interference caused by the fact that the grid-connected operation of a machine set is close to the maximum generated power.
In order to solve the technical problems, the invention provides the following technical scheme: the method comprises the steps of collecting a temperature signal A by using a resistance temperature detector; designing a filter based on a Gaussian low-pass filter, and optimizing the filter by combining a Chebyshev function; removing sine wave interference in the temperature signal by using the optimized filter to obtain a temperature signal B; and filtering the low-frequency signal in the temperature signal B through an F-P filter.
As an optimal scheme of the method for improving the anti-interference capability of the PLC temperature module according to the present invention, the method includes: the resistance temperature detector comprises a magnetic ring arranged in an input line of the resistance temperature detector.
As an optimal scheme of the method for improving the anti-interference capability of the PLC temperature module according to the present invention, the method includes: designing the filter includes employing a butterworth low pass filter as the filter, and setting a specification of the filter based on the low pass filter.
As an optimal scheme of the method for improving the anti-interference capability of the PLC temperature module according to the present invention, the method includes: the technical indicators include bandwidth, rejection height at low stopband, and in-band return loss.
As an optimal scheme of the method for improving the anti-interference capability of the PLC temperature module according to the present invention, the method includes: and the optimization filter comprises the steps of selecting the Chebyshev function as an approximation function of the filter, determining the number of resonant cavities according to the approximation function, and finishing the optimization of the filter.
As an optimal scheme of the method for improving the anti-interference capability of the PLC temperature module according to the present invention, the method includes: the Chebyshev function includes a transfer function S11：
Reflection function S21：
Wherein, M is zero point number, k is time delay weight, omega is time frequency variable, epsilon is equal ripple constant of omega + -1, FN(ω)、FN(ω)、PNAnd (ω) is a characteristic polynomial of the chebyshev function.
As an optimal scheme of the method for improving the anti-interference capability of the PLC temperature module according to the present invention, the method includes: the filtering process may include the steps of,
wherein, F (e)jω) For the filtered signal spectrum, ejωIs a complex exponential sequence, q is a frequency shift quantity, omega1Is the angular frequency corresponding to the frequency band of the filtered baseband signal.
As an optimal scheme of the method for improving the anti-interference capability of the PLC temperature module according to the present invention, the method includes: the F-P filter is composed of two self-focusing lenses.
The invention has the beneficial effects that: according to the invention, the anti-interference capability of the PLC temperature acquisition module is improved by optimizing the resistance temperature detector and the filter, and the improved PLC temperature acquisition module has the advantages of wide measurement range, strong practicability, high precision and high reliability.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
fig. 1 is a schematic diagram illustrating a response process of a filter of an interference rejection capability improving method for a PLC temperature module according to a first embodiment of the present invention;
fig. 2 is a schematic diagram of low-frequency interference filtering of an interference rejection capability improving method for a PLC temperature module according to a first embodiment of the present invention;
fig. 3 is a schematic diagram of an interference triangular wave of a simulated power plant site for an interference rejection capability improving method of a PLC temperature module according to a second embodiment of the present invention;
fig. 4 is a schematic diagram of a filtering result of an interference rejection capability improving method for a PLC temperature module according to a second embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, and it is apparent that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention, shall fall within the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
The present invention will be described in detail with reference to the drawings, wherein the cross-sectional views illustrating the structure of the device are not enlarged partially in general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected and connected" in the present invention are to be understood broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected; they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
Referring to fig. 1 to 2, a first embodiment of the present invention provides a method for improving interference rejection capability of a PLC temperature module, including:
s1: and acquiring a temperature signal A by using a resistance temperature detector.
A magnetic ring is arranged in an input line of the resistance temperature detector to weaken high-frequency interference coupled on the input line.
S2: and designing a filter based on a Gaussian low-pass filter, and optimizing the filter by combining a Chebyshev function.
A Butterworth low-pass filter is adopted as the filter, and the technical index of the filter is set based on the low-pass filter.
Wherein the technical indicators include bandwidth, rejection height at a low-end stop band, and in-band return loss; the bandwidth is set to 800 MHz; the suppression height at the low-end stop band is set to 30 dB; the in-band return loss is set to 30 dB.
Further, a Chebyshev function is selected as an approximation function of the filter, the number of resonant cavities is determined according to the approximation function, and optimization of the filter is completed.
Wherein the Chebyshev function comprises:
(1) transfer function S11：
(2) Reflection function S21：
Wherein, M is zero point number, k is time delay weight, omega is time frequency variable, epsilon is equal ripple constant of omega + -1, FN(ω)、FN(ω)、PNAnd (ω) is a characteristic polynomial of the chebyshev function.
The number of resonators is determined to be 5 according to an approximation function.
S3: and removing sine wave interference in the temperature signal by using the optimized filter to obtain a temperature signal B.
The response of the output of the filter to the input signal requires at least 5 sampling periods, fig. 1 demonstrates the response process of the filter, where T is the sampling period of the filter, and the calculation formula of the sampling period is:
T＝(4*32*Fs+T1)/fclk
wherein Fs is the temperature data output frequency, when FsWhen 1, T1When F is 61s>1 hour, T1＝95，fclkIs the frequency of the filter clock signal.
S4: and filtering the low-frequency signal in the temperature signal B through an F-P filter.
It should be noted that the F-P filter is composed of two self-focusing lenses, and avoids the diffraction loss of light in the air gap.
The signal spectrum obtained after the filtering processing of the F-P filter is as follows:
wherein, F (e)jω) For the filtered signal spectrum, ejωIs a complex exponential sequence, q is a frequency shift quantity, omega1Is the angular frequency corresponding to the frequency band of the filtered baseband signal.
Preferably, the F-P filter has a good suppression effect on 50Hz (+/-1 Hz) power frequency interference signals, fig. 2 shows the filtering effect of the filter of the thermal resistance module on low frequency interference, and the attenuation of the filter can reach 120dB for 50Hz power frequency interference.
Example 2
In order to verify and explain the technical effect adopted in the method, the embodiment performs a simulation experiment on the temperature measurement module to verify the real effect of the method.
According to the interference waveform measured in the power plant, a triangular wave (refer to fig. 3) with the same period is adopted in a laboratory for simulation, the filtering effect of the method on the interference of the power plant is tested, and the result is shown in fig. 4; in fig. 3, the artificially simulated interference signal is a triangular wave superimposed with a high-frequency signal, the peak value of the triangular wave peak is about 2.4V, and the period is 20 ms; as can be seen from FIG. 4, the temperature jitter after the interference signal is filtered by the method is within +/-0.3 ℃, and the expected effect is achieved by simulating the interference test.
Furthermore, the precision of the PLC temperature acquisition module is tested.
(1) The resistance box qualified in verification is connected into the resistance temperature detector of the method, and numerical values are recorded on a touch screen of the PLC temperature acquisition module, and the results are shown in Table 1.
Table 1: and (5) static test results.
(2) The new RTD sensor with similar long line is connected in parallel with a resistance temperature detector, and the reading is carried out at room temperature and under the condition of heating by a dry type checking furnace respectively.
Table 2: and (6) dynamically testing the result.
As can be seen from tables 1 and 2, the filtering effect of the method is remarkable, and the temperature jump is within the range of +/-0.11 ℃.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (8)
1. The utility model provides a method for PLC temperature module interference killing feature promotes which characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
acquiring a temperature signal A by using a resistance temperature detector;
designing a filter based on a Gaussian low-pass filter, and optimizing the filter by combining a Chebyshev function;
removing sine wave interference in the temperature signal by using the optimized filter to obtain a temperature signal B;
and filtering the low-frequency signal in the temperature signal B through an F-P filter.
2. The method of claim 1 for improving immunity to interference for PLC temperature modules, wherein: the resistance temperature detector comprises a resistance temperature detector which comprises a resistor,
a magnetic ring is arranged in an input line of the resistance temperature detector.
3. The interference rejection capability enhancement method for PLC temperature modules of claim 1 or 2, wherein: the design of the filter includes the steps of,
a Butterworth low-pass filter is adopted as the filter, and the technical index of the filter is set based on the low-pass filter.
4. The method of claim 3 for interference rejection of a PLC temperature module, wherein: the technical indicators include bandwidth, rejection height at low stopband, and in-band return loss.
5. The interference rejection capability enhancement method for PLC temperature modules of claim 1 or 2, wherein: the optimization filter comprises a filter-out unit,
and selecting the Chebyshev function as an approximation function of the filter, determining the number of resonant cavities according to the approximation function, and finishing the optimization of the filter.
6. The method of claim 5 for interference rejection capability enhancement of PLC temperature modules, wherein: the chebyshev function includes a function of,
transfer function S11：
Reflection function S21：
Wherein, M is zero point number, k is time delay weight, omega is time frequency variable, epsilon is equal ripple constant of omega + -1, FN(ω)、FN(ω)、PNAnd (ω) is a characteristic polynomial of the chebyshev function.
7. The method of claim 1 for improving immunity to interference for PLC temperature modules, wherein: the filtering process may include the steps of,
wherein, F (e)jω) For the filtered signal spectrum, ejωIs a complex exponential sequence, q is a frequency shift quantity, omega1Is the angular frequency corresponding to the frequency band of the filtered baseband signal.
8. The method of claim 7 for interference rejection capability enhancement of PLC temperature modules, wherein: also comprises the following steps of (1) preparing,
the F-P filter consists of two self-focusing lenses.
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