A radar electromagnetic flowmeter monitoring management method for urban sewage

Abstract

The present application relates to a kind of radar electromagnetic flowmeter monitoring management methods for urban sewage discharge, belong to sewage measurement technical field.The method first determines global feature according to sewage discharge environment and sewage characteristics and determines the basic excitation frequency for sewage flow detection from it, then determines the medium characteristic adjustment factor and environmental disturbance adjustment factor from the two dimensions of fluid interior and exterior environment respectively Correction basic excitation frequency obtains adaptive excitation frequency, through the real-time given of adaptive excitation frequency, effectively overcome the measurement error of traditional fixed excitation mode used in contact detection mode of radar electromagnetic flowmeter under complex scene such as bubble interference, medium mutation, electromagnetic noise, can be according to the dynamic change of actual working condition, accurately match the measurement demand under different conditions, significantly improve the accuracy and stability of sewage discharge flow monitoring.

Description

Technical Field

[0001] This invention relates to the field of wastewater measurement technology, and in particular to a radar electromagnetic flowmeter monitoring and management method for urban sewage discharge. Background Technology

[0002] In the process of rapid urban development, urban sewage management has become a key link in ensuring the urban ecological environment and the quality of life of residents. Urban sewage systems are vast and complex, encompassing numerous pipes and discharge outlets, making accurate monitoring of sewage flow information crucial. Currently, advanced flow monitoring equipment for urban sewage scenarios has gradually adopted a dual-mode integrated design of "radar + electromagnetic". When the pipe is not full, it uses a 24GHz radar flow meter and a 120-123.5GHz radar water level gauge for non-contact measurement, avoiding interference from air bubbles and sediment. When the pipe is full and flooded, it automatically switches to an electromagnetic flow meter for contact flow measurement, achieving seamless coverage under all operating conditions.

[0003] However, the electromagnetic flowmeter component in these dual-mode devices still uses the traditional "fixed excitation" open-loop mode, just like the single-mode electromagnetic flowmeter. This fixed-frequency excitation parameter setting method cannot be well adapted to urban sewage discharge systems. When faced with complex operating conditions such as sudden changes in the conductivity of the sewage medium, fluctuations in bubble content, and impacts from solid particles in the sewage discharge system, the signal-to-noise ratio of the induced electromotive force generated by the electromagnetic flowmeter component during sewage flow monitoring will decrease significantly, and the signal will jump severely, affecting the measurement accuracy and stability after dual-mode switching.

[0004] In other words, the current contact measurement mode of radar electromagnetic flowmeters has a technical problem of insufficient accuracy in monitoring sewage flow. Summary of the Invention

[0005] In view of this, the present invention provides a radar electromagnetic flowmeter monitoring and management method for urban sewage discharge, so as to solve the technical problem that the contact measurement mode of the radar electromagnetic flowmeter is insufficient for sewage flow monitoring accuracy.

[0006] The present invention provides a radar electromagnetic flowmeter monitoring and management method for urban sewage discharge, comprising:

[0007] Using any radar electromagnetic flowmeter in the urban sewage system as the target flowmeter, when the target flowmeter is in contact detection mode, the basic excitation frequency at the current moment is determined based on the pipe diameter at the location of the target flowmeter, the sewage conductivity at the current moment, and the average sewage flow velocity at the preset recent historical time.

[0008] Based on the current time of the sewage bubble content, sewage solid particle concentration, sewage conductivity change rate, and sewage oil content at the location of the target flow meter, determine the media characteristic adjustment factor at the current time.

[0009] The environmental disturbance adjustment factor at the current moment is determined based on the vibration frequency at the location of the target flow meter at the current moment, the number of pump start-stop times in the preset recent historical period, the temperature change rate at the current moment, and the average humidity inside the junction box of the target flow meter in the preset recent historical period.

[0010] The adaptive excitation frequency is determined based on the basic excitation frequency, the medium characteristic adjustment factor, and the environmental disturbance adjustment factor. The target flow meter then uses the adaptive excitation frequency to detect the sewage flow velocity at the current moment.

[0011] Furthermore, determine the fundamental excitation frequency at the current moment, including:

[0012] The ratio of the difference between the median conductivity of the urban sewage system and the current conductivity of the sewage at the location of the target flow meter, calculated as the preset median conductivity of the urban sewage system, and recorded as the conductivity deviation value, is recorded as the conductivity influence term. The sum of the conductivity deviation value and the constant 1 is recorded as the conductivity influence term.

[0013] The sum of the ratio of the average sewage flow velocity at the location of the target flow meter under the preset recent historical time period to the maximum design flow velocity of the pipeline at the location of the target flow meter and the constant 1 is denoted as the flow velocity influence term;

[0014] The reference excitation frequency is obtained by looking up the table based on the pipe diameter at the location of the target flow meter. The basic excitation frequency at the current moment is determined based on the reference excitation frequency, the conductivity influence term, and the flow velocity influence term. The basic excitation frequency at the current moment is proportional to the reference excitation frequency, the conductivity influence term, and the flow velocity influence term.

[0015] Furthermore, determining the base excitation frequency at the current moment based on the reference excitation frequency, the conductivity influence term, and the flow velocity influence term includes:

[0016] The product of the conductivity effect term and the flow velocity effect term is multiplied by the larger of the preset lower limit protection value and the reference excitation frequency to obtain the basic excitation frequency at the current moment; the reference excitation frequency is inversely proportional to the pipe diameter at the location of the target flow meter.

[0017] Furthermore, the adjustment factor for the medium properties at the current moment is determined, including:

[0018] The ratio of the current sewage bubble content at the location of the target flow meter to the historical maximum sewage bubble content at the location of the target flow meter is recorded as the first medium characteristic characterization item.

[0019] The difference between the current concentration of solid particles in the wastewater at the location of the target flow meter and the average concentration of solid particles in the wastewater at the location of the target flow meter over the preset recent historical period is recorded as the solid particle concentration excess. The solid particle concentration excess is 0 when the current concentration of solid particles in the wastewater at the location of the target flow meter is less than the average concentration of solid particles in the wastewater at the location of the target flow meter over the preset recent historical period. The normalized value of the solid particle concentration excess is recorded as the second medium characteristic characterization item.

[0020] The normalized value of the rate of change of sewage conductivity at the current time at the location of the target flow meter is denoted as the third medium characteristic term;

[0021] The ratio of the current sewage oil content at the location of the target flow meter to the historical maximum sewage oil content at the location of the target flow meter is recorded as the fourth media characteristic characterization item.

[0022] The average value of the first medium characteristic characterization item, the second medium characteristic characterization item, the third medium characteristic characterization item, and the fourth medium characteristic characterization item is recorded as the medium characteristic adjustment factor at the current time.

[0023] Furthermore, determine the environmental disturbance adjustment factor at the current moment, including:

[0024] The normalized value of the difference obtained by subtracting the basic excitation frequency from the vibration frequency at the current time at the location of the target flow meter by a preset multiple is recorded as the first environmental disturbance characterization term.

[0025] The normalized value of the ratio of the number of pump start-stop times under the preset recent history duration to the preset recent history duration is denoted as the second environmental disturbance characterization term.

[0026] The ratio between the absolute value of the current temperature change rate at the location of the target flow meter and the absolute value of the historical maximum temperature change rate at the location of the target flow meter is denoted as the third environmental disturbance characterization term.

[0027] The difference between constant 1 and the average humidity inside the target flow meter junction box under the preset recent historical time is recorded as the fourth environmental disturbance characterization term.

[0028] The cumulative product of the mean of the first environmental disturbance characterization term and the second environmental disturbance characterization term with the third environmental disturbance characterization term and the fourth environmental disturbance characterization term is recorded as the environmental disturbance adjustment factor at the current time.

[0029] Further, determining the adaptive excitation frequency includes:

[0030] The sum of constant 1 and the medium characteristic adjustment factor at the current time is denoted as the medium characteristic adjustment coefficient, and the sum of constant 1 and the environmental disturbance adjustment factor at the current time is denoted as the environmental disturbance adjustment coefficient.

[0031] The adaptive excitation frequency is defined as the cumulative product of the current basic excitation frequency, the medium characteristic adjustment coefficient, and the environmental disturbance adjustment coefficient.

[0032] The advantages of this invention compared to the prior art are:

[0033] This invention effectively overcomes the measurement errors of the traditional fixed excitation mode used in the contact detection mode of radar electromagnetic flowmeters under complex scenarios such as bubble interference, medium change, and electromagnetic noise by using adaptive excitation frequency and linkage filtering. It can accurately match the measurement requirements under different conditions according to the dynamic changes of actual working conditions, and significantly improve the accuracy and stability of sewage flow monitoring. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic flowchart of a radar electromagnetic flowmeter monitoring and management method for urban sewage discharge provided in Embodiment 1 of the present invention. Detailed Implementation

[0036] The overall concept of this invention is as follows:

[0037] This invention adaptively adjusts the fixed excitation frequency of a radar electromagnetic flowmeter in contact detection mode. First, a base excitation frequency is obtained based on the three most stable global characteristics: pipe diameter, conductivity, and average flow velocity, serving as the starting point for subsequent adjustments. Then, media adjustment factors and environmental adjustment factors are obtained from both internal and external perspectives. Next, the base excitation frequency is fused with these two adjustment factors to obtain the final adaptive excitation frequency. Finally, the signal excitation of the electromagnetic flowmeter in contact mode is completed based on the adaptive excitation frequency.

[0038] To further illustrate the technical solution of the present invention, specific embodiments are described below.

[0039] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of the invention include a particular feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. Furthermore, a particular feature, structure, or characteristic in one or more embodiments may be combined in any suitable form, and the terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless otherwise specifically emphasized.

[0040] It should be understood that the sequence number of each step in the following embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0041] Method Implementation Examples:

[0042] See Figure 1 This is a flowchart illustrating a radar electromagnetic flowmeter monitoring and management method for urban sewage discharge, as provided in Embodiment 1 of the present invention. Figure 1 As shown, the method may include the following steps:

[0043] S101, taking any radar electromagnetic flowmeter in the urban sewage system as the target flowmeter, when the target flowmeter is in contact detection mode, the basic excitation frequency at the current moment is determined according to the pipe diameter at the location of the target flowmeter, the sewage conductivity at the current moment, and the average sewage flow velocity at the preset recent historical time.

[0044] Urban sewage systems have a large and complex pipeline network, which uses a large number of related detection devices to detect sewage flow velocity information. Therefore, there are also a large number of dual-mode detection devices such as radar electromagnetic flowmeters. For the sake of convenience in the following discussion, this embodiment will use any radar electromagnetic flowmeter as the target flowmeter for the subsequent analysis.

[0045] To facilitate subsequent analysis, it is first necessary to obtain various relevant data required for the analysis. The following data are all relevant data from the target flow meter, which will not be described in detail.

[0046] Fluid conductivity: Measured and collected in real time by a conductivity sensor to detect changes in conductivity in real time;

[0047] Average flow velocity in the pipeline: The flow velocity is calculated by measuring the induced electromotive force generated by the fluid cutting magnetic lines of force through the electromagnetic flowmeter itself, combined with relevant algorithms. The flow velocity is collected in real time to capture rapid changes in the flow velocity. The average flow velocity is the average flow velocity under the preset recent history time. The preset recent history time can be set according to the detection accuracy requirements. In this embodiment, the value is 1 minute.

[0048] Nominal pipe diameter: Pipe design parameter, input during system initialization;

[0049] Bubble content: Estimated by ultrasonic or conductivity fluctuation method. The ultrasonic method utilizes the reflection and scattering characteristics of ultrasonic waves by bubbles, while the conductivity fluctuation method estimates the bubble content by monitoring the fluctuation of conductivity. Real-time data acquisition is required to promptly capture changes in bubble content.

[0050] Solid particle concentration: The concentration of solid particles is indirectly reflected by measuring the turbidity of the fluid through a turbidimeter or by conductivity noise spectrum analysis. The turbidimeter measures the turbidity of the fluid to reflect the concentration of solid particles, while conductivity noise spectrum analysis estimates the concentration of solid particles by monitoring the noise characteristics of conductivity. Real-time data acquisition is used to track the dynamic changes in the concentration of solid particles.

[0051] Medium temperature: Measured by a PT100 sensor. The PT100 is a commonly used temperature sensor whose resistance changes with temperature. The temperature can be calculated by measuring the resistance value. Real-time data acquisition is used to sense the trend of temperature change.

[0052] Oil content: Estimated by optical or capacitance methods. The optical method utilizes the light absorption or scattering characteristics of oil, while the capacitance method utilizes the difference between the dielectric constant of oil and water to estimate the oil content. Real-time data collection is used to track changes in oil content.

[0053] External electromagnetic interference intensity: Through analysis of the additional coil, the additional coil can sense the surrounding electromagnetic field. The intensity of electromagnetic interference is evaluated by measuring the induced electromotive force in the coil. Real-time acquisition is used to monitor the dynamic changes of electromagnetic interference.

[0054] Pipeline vibration amplitude: Measured by an accelerometer, which can measure the vibration acceleration of the pipeline. The vibration amplitude can be obtained through integration and other calculations. Real-time acquisition is used to accurately capture vibration characteristics.

[0055] Pump start-stop frequency: Identified by changes in current or pressure. Monitoring changes in pump current or pipeline pressure, when significant fluctuations in current or pressure occur, it is determined that the pump is starting or stopping. Real-time monitoring of current or pressure signals is used to accurately identify pump start-stop events. Here, the pump refers to the sewage pump (or lift pump) in the urban sewage pipeline system, which is used to transport sewage from a low place to a high place or to drive the flow of sewage. Since it is difficult to directly identify which pumps are related to the current target flow meter, this embodiment uses the current or pressure change to determine the pump start-stop frequency. It can adaptively determine the relevant pumps or eliminate the need to manually identify which pumps are related to the current target flow meter.

[0056] Ambient temperature and humidity: Calculated by temperature and humidity sensors inside the chassis. The ambient temperature inside the chassis is continuously measured by a temperature sensor and collected in real time to ensure the accuracy of the rate of change calculation. Since this embodiment ultimately achieves adaptive setting of the working parameters of the radar electromagnetic flowmeter, the chassis here refers to the chassis of the radar electromagnetic flowmeter signal processing unit or controller.

[0057] Since radar electromagnetic flowmeters are not affected by media interference such as bubbles and silt, or by environmental interference, when in non-contact detection mode, this embodiment only adaptively adjusts the excitation frequency of the radar electromagnetic flowmeter when in contact detection mode. Therefore, it is first determined whether the current target flowmeter is in contact detection mode, and subsequent analysis is performed if it is determined to be in contact detection mode. Furthermore, to conserve computational resources, all relevant data required for the aforementioned analysis are only collected when the current target flowmeter is in contact detection mode.

[0058] In urban sewage discharge scenarios, pipe diameter, conductivity, and average flow velocity are extremely stable and critical global characteristics. Pipe diameter determines the size of the fluid flow space within the pipe. Large-diameter and small-diameter pipes differ significantly in signal sensing time; large-diameter pipes require a higher fundamental frequency to ensure sufficient signal integration time, while small-diameter pipes do the opposite. Therefore, pipe diameter is a crucial factor in determining the fundamental frequency. Conductivity directly affects the signal generation of the electromagnetic flowmeter. Fluids with different conductivity require different excitation frequencies; high-conductivity fluids can be excited at low frequencies, while low-conductivity fluids require high-frequency excitation to enhance the signal. Average flow velocity affects the signal bandwidth; at high flow velocities, the signal spectrum expands to higher frequencies, necessitating a higher frequency to capture rapid fluctuations. Calculating the fundamental excitation frequency based on these three stable characteristics provides a stable and conventional benchmark value for subsequent adjustments, ensuring a reasonable starting point for the entire adaptive control process.

[0059] Therefore, when the target flow meter is in contact detection mode, the basic excitation frequency at the current moment can be determined based on the pipe diameter at the location of the target flow meter, the current sewage conductivity, and the average sewage flow velocity over a preset historical period, including:

[0060] The ratio of the difference between the median conductivity of the urban sewage system and the current conductivity of the sewage at the location of the target flow meter, calculated as the preset median conductivity of the urban sewage system, and recorded as the conductivity deviation value, is recorded as the conductivity influence term. The sum of the conductivity deviation value and the constant 1 is recorded as the conductivity influence term.

[0061] The sum of the ratio of the average sewage flow velocity at the location of the target flow meter under the preset recent historical time period to the maximum design flow velocity of the pipeline at the location of the target flow meter and the constant 1 is denoted as the flow velocity influence term;

[0062] The reference excitation frequency is obtained by looking up the table based on the pipe diameter at the location of the target flow meter. The basic excitation frequency at the current moment is determined based on the reference excitation frequency, the conductivity influence term, and the flow velocity influence term. The basic excitation frequency at the current moment is proportional to the reference excitation frequency, the conductivity influence term, and the flow velocity influence term.

[0063] Furthermore, to avoid the wastewater conductivity at the target flow meter location being too high at the current moment, which would result in an insufficiently calculated basic excitation frequency and prevent the target flow meter from functioning properly, the preferred basic excitation frequency is:

[0064]

[0065] in, This represents the basic excitation frequency of the target flow meter at time i. This indicates the reference excitation frequency obtained by looking up a table based on the pipe diameter at the location of the target flow meter. In this embodiment, looking up the table preferably refers to determining which preset pipe diameter range the current pipe diameter falls into. For example, when the pipe diameter is ≤ 300 mm, 75 Hz is used; when 300 mm < pipe diameter ≤ 800 mm, 50 Hz is used; and when the pipe diameter > 800 mm, 25 Hz is used. That is, the reference excitation frequency is inversely proportional to the pipe diameter at the location of the target flow meter. This represents the preset median conductivity of wastewater in the urban sewage system. It can be determined based on the median of all possible conductivity values ​​for the current urban sewage system, or it can be determined empirically. In this embodiment, a preferred value is 500 μS / cm. This represents the conductivity of the wastewater at the location of the target flow meter at time i. This means that high-conductivity fluids can be energized with lower-frequency excitation, while low-conductivity fluids require high-frequency excitation to enhance the signal. This represents the average flow velocity in the pipeline at the location of the target flow meter at the i-th moment, which is also the average flow velocity of sewage over the most recent historical time period (e.g., 1 minute) prior to the i-th moment (calculated from the flow velocity detected by the target flow meter itself). This indicates the maximum design flow velocity in the pipe at the location of the target flow meter, typically taken as 5 meters per second. This indicates that the signal spectrum expands to higher frequencies under high flow rates, requiring an increase in frequency to capture rapid fluctuations. Simultaneously, due to the reference excitation frequency... Since the lower limit is set according to the pipe diameter, there is no need to further reduce the excitation frequency at low flow rates, otherwise it would lead to a deterioration in the signal-to-noise ratio. Instead, the excitation frequency only needs to be adjusted upwards at high flow rates to capture high-frequency fluctuations. Therefore, this item is set to a value of not less than 1. This represents the lower limit protection value, used to ensure that the final obtained basic excitation frequency does not get too close to 0, which could cause the target flowmeter to malfunction subsequently. Its preferred value is 0.3. This indicates taking the maximum value.

[0066] S102, determine the media characteristic adjustment factor at the current moment based on the sewage bubble content, sewage solid particle concentration, sewage conductivity change rate, and sewage oil content at the current location of the target flow meter.

[0067] While the aforementioned steps yielded the basic excitation frequency, urban sewage treatment conditions are complex and variable, and relying solely on the basic excitation frequency is insufficient to handle various interferences. The reason is:

[0068] Regarding the internal characteristics of the medium, factors such as bubble content and solid particle concentration directly affect signal quality. For example, bubbles can obscure the electrodes, and solid particles can generate noise by impacting the electrodes. These issues require adjusting the excitation frequency to optimize the signal. External environmental disturbances are also significant. External electromagnetic interference and pipeline vibration can interfere with the excitation magnetic field or generate false signals. If external electromagnetic interference coincides with the excitation frequency, the signal will be overwhelmed.

[0069] Calculating the adjustment factor from both the internal and external dimensions of the medium allows for a comprehensive and detailed quantification of the impact of different factors on the excitation frequency, making the adjustment more targeted and accurate, and providing a key basis for obtaining a precise adaptive excitation frequency.

[0070] Among them, the medium characteristic adjustment factor focuses on the influence of the fluid's composition, phase state, and chemical properties on the excitation frequency.

[0071] First, the bubble content is a key factor. Bubbles are easily entrained in urban sewage, and as insulators, they can block the effective area of ​​the electrodes, causing signal jumps. The higher the bubble content, the more the excitation frequency needs to be increased to increase the number of samplings. Data is recovered using the effective signals generated by bubble bursting. Therefore, this factor increases positively when the bubble content is high. Second, the concentration of solid particles cannot be ignored. Mud and sand impacting the electrodes will generate spike noise. High-frequency excitation can disperse the noise spectrum, making it easier for digital filtering to remove, while reducing the impact of particle shielding. Therefore, this factor will also adjust positively at high concentrations. At the same time, the rate of change of conductivity reflects sudden changes in the medium. When the change is drastic, the frequency needs to be temporarily increased significantly to track quickly and avoid measurement lag. Finally, when the grease content is high, low-frequency excitation has difficulty penetrating the oil film, while high-frequency excitation obtains signals through capacitive coupling. Therefore, this factor increases significantly when the grease content is high.

[0072] Therefore, it is possible to set, based on the current sewage bubble content, sewage solid particle concentration, sewage conductivity change rate, and sewage oil content at the location of the target flow meter, to determine the media characteristic adjustment factor at the current moment, including:

[0073] The ratio of the current sewage bubble content at the location of the target flow meter to the historical maximum sewage bubble content at the location of the target flow meter is recorded as the first medium characteristic characterization item.

[0074] The difference between the current concentration of solid particles in the wastewater at the location of the target flow meter and the average concentration of solid particles in the wastewater at the location of the target flow meter over the preset recent historical period is recorded as the solid particle concentration excess. The solid particle concentration excess is 0 when the current concentration of solid particles in the wastewater at the location of the target flow meter is less than the average concentration of solid particles in the wastewater at the location of the target flow meter over the preset recent historical period. The normalized value of the solid particle concentration excess is recorded as the second medium characteristic characterization item.

[0075] The normalized value of the rate of change of sewage conductivity at the current time at the location of the target flow meter is denoted as the third medium characteristic term;

[0076] The ratio of the current sewage oil content at the location of the target flow meter to the historical maximum sewage oil content at the location of the target flow meter is recorded as the fourth media characteristic characterization item.

[0077] The average value of the first medium characteristic characterization item, the second medium characteristic characterization item, the third medium characteristic characterization item, and the fourth medium characteristic characterization item is recorded as the medium characteristic adjustment factor at the current time.

[0078] The formula for the medium property adjustment factor is as follows:

[0079]

[0080] in, This represents the adjustment factor for the medium characteristics of the target flow meter at time i. This represents the bubble content at the location of the target flow meter at time i. This indicates the historical maximum concentration of air bubbles in wastewater at the location of the target flow meter. This indicates that the factor increases positively when the bubble content is high. This represents the concentration of solid particles in the wastewater at the location of the target flow meter at time i. This represents the average concentration of solid particles in wastewater at the location of the target flow meter up to the i-th time point, within the preset recent history duration (e.g., 1 minute). It is easy to understand that this preset recent history duration can also be different from the aforementioned preset recent history duration. This indicates that the greater the current solid particle concentration exceeds the recent average, the more necessary it is to positively adjust the excitation frequency. Physically, however, positive adjustment should not be made when the solid particle concentration is below the average. If the value is negative, then take 0 directly. This represents the conductivity of the wastewater at the location of the target flow meter at time i. This represents the conductivity of the wastewater at the location of the target flow meter at time i-1. This represents the difference in conductivity between the current moment and the previous moment, divided by the time interval between the two moments, i.e., the rate of change of conductivity. The larger this value, the more necessary it is to temporarily and significantly increase the frequency for rapid tracking. This indicates the oil and grease content of the wastewater at the location of the target flow meter at time i. This indicates the historical maximum oil and grease content in wastewater at the location of the target flow meter. This indicates that the higher the grease content, the more likely a high-frequency excitation should be used to obtain the signal through capacitive coupling, since low-frequency excitation has difficulty penetrating the oil film. Therefore, this factor increases significantly when the grease content is high. This indicates that the data within parentheses has been normalized to its maximum and minimum values ​​based on all data collected since the start of monitoring.

[0081] S103, determine the environmental disturbance adjustment factor at the current moment based on the vibration frequency at the location of the target flow meter at the current moment, the number of pump start-stops over the preset recent historical period, the temperature change rate at the current moment, and the average humidity inside the junction box of the target flow meter over the preset recent historical period.

[0082] The environmental disturbance adjustment factor mainly considers the interference and compensation requirements of external mechanical, electromagnetic, and climatic environmental factors on the excitation frequency.

[0083] First, regarding the amplitude of pipeline vibration, low-frequency vibration can cause false electromotive force due to relative electrode movement. If the excitation frequency is close to the vibration frequency, the beat effect will amplify the error. A frequency more than three times higher than the vibration frequency should be selected. The greater the vibration, the more positive adjustment this factor needs to be. Second, the pump start-up and shutdown frequency affects the flow state. At the moment of start-up and shutdown, it is necessary to switch to the highest excitation frequency to capture the transient waveform. The higher the start-up and shutdown frequency, the larger the average factor. In addition, the rate of change of ambient temperature will cause the circuit component parameters to drift, affecting the accuracy of the excitation frequency. When the rate of change is large, dynamic compensation is required. The adjustment amount is related to the absolute value of the rate of change. Finally, when the humidity inside the junction box of the electromagnetic flowmeter sensor is high, the insulation of the junction box decreases, introducing leakage current noise. High-frequency excitation is more sensitive. At this time, the excitation frequency should be appropriately reduced to reduce the impact of leakage.

[0084] Therefore, an environmental disturbance adjustment factor can be set based on the vibration frequency at the current location of the target flow meter, the number of pump start-stop cycles over the preset recent historical period, the temperature change rate at the current moment, and the average humidity inside the target flow meter junction box over the preset recent historical period. This factor includes:

[0085] The normalized value of the difference obtained by subtracting the basic excitation frequency from the vibration frequency at the current time at the location of the target flow meter by a preset multiple is recorded as the first environmental disturbance characterization term.

[0086] The normalized value of the ratio of the number of pump start-stop times under the preset recent history duration to the preset recent history duration is denoted as the second environmental disturbance characterization term.

[0087] The ratio between the absolute value of the current temperature change rate at the location of the target flow meter and the absolute value of the historical maximum temperature change rate at the location of the target flow meter is denoted as the third environmental disturbance characterization term.

[0088] The difference between constant 1 and the average humidity inside the target flow meter junction box under the preset recent historical time is recorded as the fourth environmental disturbance characterization term.

[0089] The cumulative product of the mean of the first environmental disturbance characterization term and the second environmental disturbance characterization term with the third environmental disturbance characterization term and the fourth environmental disturbance characterization term is recorded as the environmental disturbance adjustment factor at the current time.

[0090] The formula for the environmental disturbance adjustment factor is as follows:

[0091]

[0092] in, This represents the environmental disturbance adjustment factor of the target flow meter at time i. This represents a preset multiplier; in this implementation, a value of 3 is preferred. This indicates the vibration frequency at the current moment at the location of the target flow meter. This represents the fundamental excitation frequency of the target flowmeter at time i, a preferred value based on a preset multiple. This indicates that the greater the current vibration frequency (3 times the base excitation frequency) is above the base excitation frequency, the more the base excitation frequency should be adjusted positively. This indicates the number of times the water pump has started and stopped within the preset recent historical time (1 minute). The preset recent historical time is also specified. This indicates the recent pump start-up and shutdown frequency. The higher this frequency, the more positively the excitation frequency should be adjusted. It's easy to understand that the pump start-up and shutdown frequency can also be obtained based on the most recent time period of other durations. This represents the slope value of the first-order fit of temperature data over a preset historical time period, which is also the recent rate of temperature change. This indicates taking the absolute value. This represents the absolute value of the historical maximum rate of temperature change at the location of the target flow meter, used to eliminate dimensions. This indicates that the greater the recent temperature change rate, the more positively the excitation frequency should be adjusted. It also indicates the average humidity inside the target flowmeter junction box over the most recent historical period (1 minute), expressed as a humidity ratio (ranging from 0 to 1). Higher humidity leads to decreased junction box insulation, introducing leakage current noise, and making high-frequency excitation more sensitive. In this case, the excitation frequency should be appropriately reduced to minimize leakage effects. In a straightforward manner, this average humidity value can also be obtained based on the most recent time period of other durations. This indicates that the data within parentheses has been normalized to its maximum and minimum values ​​based on all data collected since the start of monitoring.

[0093] S104, the adaptive excitation frequency is determined based on the basic excitation frequency, the medium characteristic adjustment factor, and the environmental disturbance adjustment factor, and the target flow meter completes the sewage flow velocity detection at the current moment based on the adaptive excitation frequency.

[0094] The base excitation frequency provides a benchmark for the entire control system under normal operating conditions, but it does not consider complex dynamic disturbances. The medium characteristic adjustment factor and the environmental disturbance adjustment factor, from the perspectives of the internal fluid environment and the external environment, respectively, quantify the degree to which various disturbance factors cause the excitation frequency to deviate from the base value. Integrating the base excitation frequency with these two adjustment factors allows for a comprehensive consideration of both basic operating conditions and actual disturbances, resulting in an adaptive excitation frequency that conforms to both conventional sewage discharge characteristics and adapts to complex and variable actual operating conditions.

[0095] Specifically, after obtaining the basic excitation frequency and the two adjustment factors from the above content, the final adaptive excitation frequency can be obtained by fusing them:

[0096]

[0097] in, This represents the adaptive excitation frequency of the target flow meter at time i. This represents the basic excitation frequency of the target flow meter at time i. This represents the adjustment factor for the medium characteristics of the target flow meter at time i. This represents the environmental disturbance adjustment factor of the target flow meter at time i. This indicates that the base excitation frequency increases as the two adjustment factors increase.

[0098] In addition, to ensure that the calculated adaptive excitation frequency conforms to the actual operating conditions, it is necessary to... Limit the amplitude, that is, if If the calculated result is less than the minimum allowable frequency, the minimum allowable frequency is taken; if it is greater than the maximum allowable frequency, the maximum allowable frequency is taken; otherwise, the original value is retained. In this embodiment, the minimum allowable frequency is preferably 5 Hz, which is used for special scenarios where the conductivity is extremely low or the vibration is strong and low-frequency resonance needs to be avoided. The maximum allowable frequency is preferably 150 Hz, which is used for scenarios where the bubble content is high or the highest sampling rate is required at the moment of pump start-up and shutdown.

[0099] After obtaining the final adaptive excitation frequency according to the above steps, the radar electromagnetic flowmeter system first outputs this frequency to the excitation drive circuit, generating an alternating excitation current of the corresponding frequency to drive the excitation coil of the electromagnetic flowmeter to establish an alternating magnetic field. Simultaneously, the cutoff frequency of the digital low-pass filter is updated according to the linkage rules, typically set to 0.4 times the final excitation frequency. The filter order is adjusted based on the frequency: at higher frequencies, the order is appropriately reduced to maintain response speed, while at lower frequencies, the order is increased to improve noise suppression. Subsequently, the induced electromotive force signal is acquired through electrodes, pre-amplified, and converted from analog to digital before being fed into a digital filter with a set cutoff frequency for real-time filtering. The filtered signal is converted into instantaneous flow velocity according to Faraday's law of electromagnetic induction, i.e., the induced electromotive force divided by the product of the instrument coefficient, magnetic field strength, and pipe diameter. The magnetic field strength is determined by the excitation current and coil parameters. The instantaneous flow velocity is multiplied by the pipe cross-sectional area and integrated over time to obtain the cumulative flow rate. Finally, the system uploads instantaneous flow rate, cumulative flow rate, current adaptive excitation frequency, and various adjustment factors to the urban sewage monitoring center via the communication interface. At the same time, it stores the measurement data of the current window in the local cache, slides the window with a one-second window length and a 0.2-second step size, and repeats all the steps to achieve continuous, adaptive, and high-precision monitoring of sewage pipeline flow.

[0100] This invention, through adaptive excitation frequency and linked filtering, effectively overcomes the measurement errors of the traditional fixed excitation mode used in the contact detection mode of radar electromagnetic flowmeters under complex scenarios such as bubble interference, medium abrupt changes, and electromagnetic noise. It can accurately match the measurement requirements under different conditions according to the dynamic changes of actual working conditions, significantly improving the accuracy and stability of sewage flow monitoring, overcoming the limitations of the traditional fixed excitation mode, and providing reliable protection for flow monitoring in various complex scenarios.

[0101] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A radar electromagnetic flowmeter monitoring and management method for urban sewage discharge, characterized in that, The method includes: Using any radar electromagnetic flowmeter in the urban sewage system as the target flowmeter, when the target flowmeter is in contact detection mode, the basic excitation frequency at the current moment is determined based on the pipe diameter at the location of the target flowmeter, the sewage conductivity at the current moment, and the average sewage flow velocity at the preset recent historical time. Based on the current time of the sewage bubble content, sewage solid particle concentration, sewage conductivity change rate, and sewage oil content at the location of the target flow meter, determine the media characteristic adjustment factor at the current time. The environmental disturbance adjustment factor at the current moment is determined based on the vibration frequency at the location of the target flow meter at the current moment, the number of pump start-stop times in the preset recent historical period, the temperature change rate at the current moment, and the average humidity inside the junction box of the target flow meter in the preset recent historical period. The adaptive excitation frequency is determined based on the basic excitation frequency, the medium characteristic adjustment factor, and the environmental disturbance adjustment factor. The target flow meter then uses the adaptive excitation frequency to detect the sewage flow velocity at the current moment.

2. The radar electromagnetic flowmeter monitoring and management method for urban sewage discharge according to claim 1, characterized in that, Determine the base excitation frequency at the current moment, including: The ratio of the difference between the median conductivity of the urban sewage system and the current conductivity of the sewage at the location of the target flow meter, calculated as the preset median conductivity of the urban sewage system, and recorded as the conductivity deviation value, is recorded as the conductivity influence term. The sum of the conductivity deviation value and the constant 1 is recorded as the conductivity influence term. The sum of the ratio of the average sewage flow velocity at the location of the target flow meter under the preset recent historical time period to the maximum design flow velocity of the pipeline at the location of the target flow meter and the constant 1 is denoted as the flow velocity influence term; The reference excitation frequency is obtained by looking up the table based on the pipe diameter at the location of the target flow meter. The basic excitation frequency at the current moment is determined based on the reference excitation frequency, the conductivity influence term, and the flow velocity influence term. The basic excitation frequency at the current moment is proportional to the reference excitation frequency, the conductivity influence term, and the flow velocity influence term.

3. The radar electromagnetic flowmeter monitoring and management method for urban sewage discharge according to claim 2, characterized in that, Determining the base excitation frequency at the current moment based on the reference excitation frequency, the conductivity influence term, and the flow velocity influence term includes: The product of the conductivity effect term and the flow velocity effect term is multiplied by the larger of the preset lower limit protection value and the reference excitation frequency to obtain the basic excitation frequency at the current moment; the reference excitation frequency is inversely proportional to the pipe diameter at the location of the target flow meter.

4. The radar electromagnetic flowmeter monitoring and management method for urban sewage discharge according to claim 1, characterized in that, Determine the medium property adjustment factor at the current moment, including: The ratio of the current sewage bubble content at the location of the target flow meter to the historical maximum sewage bubble content at the location of the target flow meter is recorded as the first medium characteristic characterization item. The difference between the current concentration of solid particles in the wastewater at the location of the target flow meter and the average concentration of solid particles in the wastewater at the location of the target flow meter over the preset recent historical period is recorded as the solid particle concentration excess. The solid particle concentration excess is 0 when the current concentration of solid particles in the wastewater at the location of the target flow meter is less than the average concentration of solid particles in the wastewater at the location of the target flow meter over the preset recent historical period. The normalized value of the solid particle concentration excess is recorded as the second medium characteristic characterization item. The normalized value of the rate of change of sewage conductivity at the current time at the location of the target flow meter is denoted as the third medium characteristic term; The ratio of the current sewage oil content at the location of the target flow meter to the historical maximum sewage oil content at the location of the target flow meter is recorded as the fourth media characteristic characterization item. The average value of the first medium characteristic characterization item, the second medium characteristic characterization item, the third medium characteristic characterization item, and the fourth medium characteristic characterization item is recorded as the medium characteristic adjustment factor at the current time.

5. The radar electromagnetic flowmeter monitoring and management method for urban sewage discharge according to claim 1, characterized in that, Determine the environmental disturbance adjustment factor at the current moment, including: The normalized value of the difference obtained by subtracting the basic excitation frequency from the vibration frequency at the current time at the location of the target flow meter by a preset multiple is recorded as the first environmental disturbance characterization term. The normalized value of the ratio of the number of pump start-stop times under the preset recent history duration to the preset recent history duration is denoted as the second environmental disturbance characterization term. The ratio between the absolute value of the current temperature change rate at the location of the target flow meter and the absolute value of the historical maximum temperature change rate at the location of the target flow meter is denoted as the third environmental disturbance characterization term. The difference between constant 1 and the average humidity inside the target flow meter junction box under the preset recent historical time is recorded as the fourth environmental disturbance characterization term. The cumulative product of the mean of the first environmental disturbance characterization term and the second environmental disturbance characterization term with the third environmental disturbance characterization term and the fourth environmental disturbance characterization term is recorded as the environmental disturbance adjustment factor at the current time.

6. The radar electromagnetic flowmeter monitoring and management method for urban sewage discharge according to any one of claims 1 to 5, characterized in that, Determining the adaptive excitation frequency includes: The sum of constant 1 and the medium characteristic adjustment factor at the current time is denoted as the medium characteristic adjustment coefficient, and the sum of constant 1 and the environmental disturbance adjustment factor at the current time is denoted as the environmental disturbance adjustment coefficient. The adaptive excitation frequency is defined as the cumulative product of the current basic excitation frequency, the medium characteristic adjustment coefficient, and the environmental disturbance adjustment coefficient.

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