Radio current sensor, current detection method and computer program product

Abstract

The application is suitable for the technical field of sensors, and provides a wireless current sensor, a current detection method and a computer program product. The electric field power supply module and the magnetic field power supply module are respectively powered from the alternating electric field and the alternating magnetic field around the to-be-detected power transmission line, and respectively provide the first direct current and the second direct current for the energy storage module, and respectively output the first voltage sampling value and the second voltage sampling value. The processing module determines the electric field power and the magnetic field power of the to-be-detected power transmission line at the current moment according to the first voltage sampling value, the second voltage sampling value, the environmental temperature value and the environmental humidity value at the current moment. The current detection module is controlled to perform current detection based on the current detection strategy matched with the current system working condition according to the electric field power, the magnetic field power, the total harmonic distortion rate, the waveform flat top rate and the wave crest factor of the current detection signal in the current power frequency cycle, so that the current detection module has higher stability and current detection precision under all working conditions.

Description

Technical Field

[0001] This application belongs to the field of sensor technology, and in particular relates to a wireless current sensor, a current detection method, and a computer program product. Background Technology

[0002] To ensure the safe and stable operation of the power grid, wireless current sensors are typically installed on transmission lines to monitor the current values ​​in real time, thereby enabling the monitoring of the overall operating status of the transmission lines. In practical applications, the power supply problem must be solved first to ensure the proper functioning of the wireless current sensors. Traditional power supply methods for wireless current sensors include: photovoltaic power supply (i.e., obtaining electrical energy using photovoltaic power generation); battery power supply; and transmission line magnetic field power supply (i.e., using current transformers to extract power from the magnetic field generated by the transmission line).

[0003] However, photovoltaic power generation equipment is typically large and unsuitable for installation. Battery power, on the other hand, has a limited lifespan, requiring periodic battery replacements and incurring high labor costs. Power supply via the electric field of transmission lines heavily relies on the current generated by the transmission lines. When the current is low, the magnetic field strength generated by the transmission lines is insufficient, preventing the wireless current sensor from obtaining enough power to maintain normal operation and thus hindering current detection under all operating conditions. Based on this, related technologies have provided a wireless current sensor that utilizes the electric field of transmission lines for power generation; however, the power extraction and efficiency of this method are limited, making it impossible for the wireless current sensor to maintain high accuracy and stability in current detection across all operating conditions. Summary of the Invention

[0004] In view of this, embodiments of this application provide a wireless current sensor, a current detection method, and a computer program product to solve the technical problem that traditional wireless current sensors cannot maintain high current detection accuracy and stability under all operating conditions.

[0005] In a first aspect, embodiments of this application provide a wireless current sensor, including an electric field power extraction module, a magnetic field power extraction module, an energy storage module, a current detection module, an environmental sensing module, a processing module, and a wireless communication module;

[0006] The electric field power extraction module is used to couple with the transmission line under test through an electric field to obtain electrical energy from the alternating electric field around the transmission line under test, and output a first DC power to the energy storage module and output a first voltage sampling value to the processing module.

[0007] The magnetic field power extraction module is used to couple with the power transmission line under test through a magnetic field to extract electrical energy from the alternating magnetic field around the power transmission line under test, and output a second DC power to the energy storage module and output a second voltage sampling value to the processing module.

[0008] The energy storage module is used to store the electrical energy provided by the first DC power and / or the second DC power, and to provide operating voltage for the current detection module, the environmental sensing module, the processing module and the wireless communication module;

[0009] The current detection module is used to couple with the transmission line under test through a magnetic field to detect the current of the transmission line under test, and output the corresponding current detection value to the processing module so that the processing module can send the current detection value to the host computer through the wireless communication module.

[0010] The environmental sensing module is used to collect environmental temperature and humidity values, and send the environmental temperature and humidity values ​​to the processing module.

[0011] The processing module is used to: determine the electric field power of the transmission line under test at the current time based on the first voltage sampling value, the ambient temperature value, and the ambient humidity value at the current time; determine the magnetic field power of the transmission line under test at the current time based on the second voltage sampling value and the ambient temperature value at the current time; and determine the total harmonic distortion rate, waveform flat-top rate, and crest factor of the current detection signal within the current power frequency cycle; determine the current system operating condition based on the electric field power, the magnetic field power, the total harmonic distortion rate, the waveform flat-top rate, and the crest factor; and control the current detection module to detect the current of the transmission line under test based on a current detection strategy that matches the current system operating condition.

[0012] In one optional implementation of the first aspect, the processing module is specifically configured to: calculate the electric field power of the transmission line under test at the current moment based on the first voltage sampling value, the ambient temperature value, and the ambient humidity value using the following formula:

[0013] P e = K ep ·( V e / k e )·[1+ α T ( T - T 0)+ α H ( H - H 0)];

[0014] in, P e The electric field power of the transmission line under test at the current moment is... K epThis is the first conversion factor between the pre-calibrated voltage and electric field power. k e The first partial pressure coefficient, V e The first voltage sample value at the current moment. α T This is a temperature correction factor. T The ambient temperature value at the current moment. T 0 represents the calibration temperature. α H This is the humidity correction factor. H The ambient humidity value at the current moment. H 0 represents the calibrated humidity.

[0015] In one optional implementation of the first aspect, the processing module is specifically configured to: calculate the magnetic field power of the transmission line under test at the current moment based on the second voltage sampling value and the ambient temperature value using the following formula:

[0016] P m = K mp ·( V m / k m ) 2 ·[1+ α T ( T - T 0)];

[0017] in, P m The magnetic field power of the transmission line under test at the current moment is... K mp This is the pre-calibrated second conversion factor between voltage and magnetic field power. V m This is the second voltage sample value at the current moment. k m This is the second partial pressure coefficient. α T This is a temperature correction factor. T The ambient temperature value at the current moment. T 0 represents the calibration temperature.

[0018] In one optional implementation of the first aspect, the processing module is specifically configured to: perform a fast Fourier transform on the current detection value sequence within the current power frequency cycle to obtain the frequency domain component sequence corresponding to the current detection value sequence, determine the fundamental amplitude and multiple harmonic amplitudes of the current detection signal within the current power frequency cycle from the frequency domain component sequence, and calculate the total harmonic distortion rate of the current detection signal within the current power frequency cycle based on the fundamental amplitude and all the harmonic amplitudes.

[0019] In an optional implementation of the first aspect, the processing module is specifically configured to: determine, based on all the current detection values ​​within the current power frequency cycle, a target current detection point corresponding to the current peak value within the current power frequency cycle and a peak region corresponding to the target current detection point; calculate the proportion of current detection points within the peak region whose current detection values ​​are greater than a preset current threshold to all current detection points within the peak region; and determine the proportion as the waveform flat-top ratio of the current detection signal within the current power frequency cycle; wherein the preset current threshold is less than the current peak value and greater than 95% of the current peak value.

[0020] In one optional implementation of the first aspect, the processing module is specifically used to: determine the effective value of the current and the peak value of the current within the current power frequency cycle, and determine the ratio of the peak value of the current to the effective value of the current as the crest factor of the current detection signal within the current power frequency cycle.

[0021] In one alternative implementation of the first aspect, the processing module is specifically used for:

[0022] If the waveform flatness ratio is greater than the preset flatness ratio threshold, the current system operating condition is determined to be the sensor current sensing saturation condition.

[0023] If the current system operating condition is not in the sensor current saturation condition, and the total harmonic distortion rate is greater than the preset distortion rate threshold or the crest factor is greater than the preset factor threshold, then the current system operating condition is determined to be the induced current distortion condition.

[0024] If the current system is not in the sensor current saturation condition and is not in the induced current distortion condition, calculate the energy ratio of the electric field power to the magnetic field power; if the energy ratio is greater than a first ratio threshold and the electric field power is greater than a first power threshold, determine the current system operating condition as a light-load condition of the transmission line; if the energy ratio is less than a second ratio threshold, determine the current system operating condition as an overload condition of the transmission line; if the energy ratio is greater than or equal to the second ratio threshold and less than or equal to the first ratio threshold, determine the current system operating condition as a normal load condition of the transmission line.

[0025] In one alternative implementation of the first aspect, the processing module is specifically used for:

[0026] When the current system operating condition is the sensor current sensing saturation condition, the current detection module is controlled to switch from current transformer mode to Rogowski coil mode, and the current detection value output by the current detection module is marked as unreliable. The current of the transmission line under test is estimated based on the electric field-assisted current to obtain the corresponding current estimation value.

[0027] When the current system operating condition is the induced current distortion condition, the current detection module is controlled to perform current detection based on the high sampling rate mode;

[0028] When the current system is operating under the light load condition of the transmission line, the current detection module is controlled to process the induced current signal of the current detection module in a high gain mode, and the current detection value is verified using the electric field power, and the verified current detection value is corrected based on the ambient temperature value.

[0029] When the current system operating condition is the overload condition of the transmission line, the current detection module is controlled to process the current detection value in a low-gain mode and correct the current detection value based on the ambient temperature value.

[0030] When the current system is operating under normal load conditions of the transmission line, the current detection module is controlled to process the current detection value in medium gain mode and correct the current detection value based on the ambient temperature value.

[0031] Secondly, embodiments of this application provide a current detection method applied to a wireless current sensor described in any optional implementation of the first aspect, wherein the current detection method is used to implement the function of the processing module in the wireless current sensor.

[0032] Thirdly, embodiments of this application provide a computer program product, including a computer program that, when run, implements the function of the processing module in the wireless current sensor as described in any optional implementation of the first aspect.

[0033] Implementing the wireless current sensor, current detection method, and computer program provided in the embodiments of this application has the following beneficial effects:

[0034] The wireless current sensor provided in this application embodiment is equipped with both an electric field power extraction module and a magnetic field power extraction module. The two power extraction modules can complement each other under different operating conditions, thus enabling the wireless current sensor to have high stability under all operating conditions. Since the processor can identify the current system operating condition and control the current detection module to use a current detection strategy that matches the current system operating condition for current detection, the wireless current sensor can have high current detection accuracy under all operating conditions. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of a wireless current sensor provided in an embodiment of this application;

[0037] Figure 2 This is a schematic diagram of the structure of a wireless current sensor provided in another embodiment of this application. Detailed Implementation

[0038] The following embodiments are only used to illustrate the technical solutions of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0039] In the description of the embodiments of this application, the technical terms "comprising," "including," "having," and any variations thereof all mean "including but not limited to," unless otherwise specifically emphasized. In the description of the embodiments of this application, unless otherwise stated, the technical term "multiple" refers to two or more, and the technical terms "at least one" or "one or more" refer to one, two, or more than two. The technical terms "first," "second," etc., are only used to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary / secondary relationship of the indicated technical features. The technical term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0040] This application first provides a wireless current sensor. Figure 1 This is a schematic diagram of the structure of a wireless current sensor provided in an embodiment of this application. Figure 1As shown, the wireless current sensor 10 may include an electric field power harvesting module 101, a magnetic field power harvesting module 102, an energy storage module 103, a current detection module 104, an environmental sensing module 105, a processing module 106, and a wireless communication module 107. Wherein:

[0041] The electric field power extraction module 101 is connected to the energy storage module 103 and the processing module 106. The electric field power extraction module 101 is used to couple with the transmission line 20 under test via an electric field to extract electrical energy from the alternating electric field surrounding the transmission line 20, outputting a first direct current to the energy storage module 103 and a first voltage sample value to the processing module 106. The first voltage sample value is a sample value of the actual output voltage of the electric field power extraction module 101. Based on this, the actual output voltage of the electric field power extraction module 101 can be calculated from the first voltage sample value, thereby obtaining the output power of the electric field power extraction module 101 (i.e., the electric field power of the transmission line 20 under test). It should be understood that regardless of whether there is current in the transmission line 20 under test, as long as there is voltage on the transmission line 20 under test, an alternating electric field exists around the transmission line 20 under test, and the electric field power extraction module 101 can extract electrical energy.

[0042] The magnetic field power extraction module 102 is connected to the energy storage module 103 and the processing module 106. The magnetic field power extraction module 102 is used to couple with the transmission line 20 under test via a magnetic field to extract electrical energy from the alternating magnetic field surrounding the transmission line 20, outputting a second direct current to the energy storage module 103 and a second voltage sample value to the processing module 106. The second voltage sample value is a sample value of the actual output voltage of the magnetic field power extraction module 102. Based on this, the actual output voltage of the magnetic field power extraction module 102 can be calculated from the second voltage sample value, thereby obtaining the output power of the magnetic field power extraction module 102 (i.e., the magnetic field power of the transmission line 20 under test). It should be understood that when there is no current or a small current in the transmission line 20 under test, the magnetic field power extraction module 102 cannot extract electrical energy or cannot extract sufficient electrical energy.

[0043] The energy storage module 103 is also connected to the current detection module 104, the environmental sensing module 105, the processing module 106, and the wireless communication module 107. The energy storage module 103 stores electrical energy provided by the first DC power and / or the second DC power, and provides operating voltage for the current detection module 104, the environmental sensing module 105, the processing module 106, and the wireless communication module 107. It should be understood that the operating voltages of different modules in the wireless current sensor 10 can be the same or different; this embodiment does not limit this.

[0044] The current detection module 104 is also connected to the processing module 106. The current detection module 104 is used to couple with the transmission line 20 under test via a magnetic field to detect the current in the transmission line 20 based on a current detection strategy matching the current system operating conditions. It then outputs the corresponding current detection value to the processing module 106, enabling the processing module 106 to send the current detection value of the transmission line 20 under test to the host computer via the wireless communication module 107. The current detection strategy matching the current system operating conditions can be determined by the processing module 106. The specific determination process can be referred to in the relevant description of the processing module 106 section later, and will not be detailed here.

[0045] The environmental sensing module 105 is also connected to the processing module 106. The environmental sensing module 105 collects environmental temperature and humidity values ​​and sends them to the processing module 106. Optionally, the environmental sensing module 105 may collect environmental temperature and humidity values ​​once every first time interval. The first time interval can be set according to actual conditions, and this embodiment does not limit it.

[0046] The processing module 106 is used to determine the electric field power of the transmission line 20 under test at the current time based on the first voltage sampling value, the ambient temperature value, and the ambient humidity value at the current time; determine the magnetic field power of the transmission line 20 under test at the current time based on the second voltage sampling value and the ambient temperature value at the current time; and determine the total harmonic distortion rate, waveform flattening rate, and crest factor of the current detection signal within the current power frequency cycle; determine the current system operating condition based on the electric field power, magnetic field power, total harmonic distortion rate, waveform flattening rate, and crest factor, and control the current detection module to detect the current of the transmission line 20 under test based on a current detection strategy that matches the current system operating condition.

[0047] Among them, the electric field power of the transmission line 20 under test can be used to reflect the voltage level of the transmission line 20 under test.

[0048] The magnetic field power of the transmission line 20 under test can be used to reflect the current level of the transmission line 20 under test.

[0049] The power frequency period can be used to describe the time required for the alternating current in the transmission line 20 under test to complete one full sine wave change. The current power frequency period can refer to the power frequency period at the current moment, and the current moment can refer to the moment when the processing module 106 determines the current system operating condition.

[0050] The total harmonic distortion rate of the current detection signal within the current power frequency cycle is used to describe the degree of distortion of the waveform of the current detection signal relative to the standard sine wave within the current power frequency cycle. Its magnitude is used to reflect the overall proportion of harmonic components in the waveform of the current detection signal within the current power frequency cycle.

[0051] The waveform flatness ratio of the current sensing signal within the current power frequency cycle is used to describe the flatness of the waveform of the current sensing signal near the peak value within the current power frequency cycle.

[0052] The crest factor of the current detection signal within the current power frequency cycle describes the sharpness of the current detection signal waveform within the current power frequency cycle, and its magnitude reflects the proportional relationship between the peak current value and the effective current value within the current power frequency cycle. The effective current value within the current power frequency cycle refers to the size of a DC circuit that produces the same thermal effect as the alternating current in the transmission line 20 under test within the current power frequency cycle.

[0053] The current system operating condition can refer to the current operating status of the current sensing system composed of the wireless current detection module 104 and the transmission line under test 20. For example, the current system operating condition may include: sensor current sensing saturation condition, induced current distortion condition, light load condition of the transmission line, overload condition of the transmission line, and normal load condition of the transmission line.

[0054] The current sensing saturation condition refers to the condition where the current detection module 104 becomes magnetically saturated due to excessive current in the transmission line 20 under test. Under this condition, the current sensing performance of the current detection module 104 drops sharply, and its output current detection value cannot accurately reflect the current in the transmission line under test.

[0055] Induced current distortion refers to a situation where the current waveform of the transmission line under test (20) is severely distorted and no longer a standard sine wave. This condition is usually caused by nonlinear loads on the transmission line, resulting in a large number of harmonic components in the current waveform of the transmission line under test.

[0056] The light-load condition of the transmission line refers to the condition where the current in the transmission line under test is very small. Under this condition, the energy obtained by the magnetic field power harvesting module 102 from the alternating magnetic field is very small.

[0057] Overload conditions on power transmission lines refer to situations where the current in the power transmission line under test approaches or exceeds its maximum allowable current value for safe operation. This condition carries the risk of overheating of the transmission line or triggering of protective measures.

[0058] Normal load conditions for power transmission lines refer to the condition where the current in the transmission line is expected to be within the normal current range allowed by the design. This is the most common and ideal operating state for power transmission lines.

[0059] It should be understood that different system operating conditions can correspond to different current detection strategies. The processing module 106 can pre-store the correspondence between system operating conditions and current detection strategies.

[0060] In one specific implementation, the processing module 106 can be used for:

[0061] Based on the current voltage sampling value, the previous ambient temperature value, and the previous ambient humidity value, the electric field power of the transmission line 20 under test at the current moment is calculated using the following formula (1):

[0062] P e = K ep ·( V e / k e )·[1+ α T ( T - T 0)+ α H ( H - H 0)]; formula (1)

[0063] in, P e The electric field power of the transmission line 20 under test at the current moment is... K ep This is the first conversion factor between the pre-calibrated voltage and electric field power. k e The first partial pressure coefficient, V e This is the first voltage sample value at the current moment. α T This is a temperature correction factor. T The ambient temperature value at the current moment. T 0 represents the calibration temperature. α H This is the humidity correction factor. H The current ambient humidity value. H 0 represents the calibrated humidity.

[0064] The first conversion factor between voltage and electric field power can be measured experimentally.

[0065] The first voltage divider coefficient can be determined based on the first resistor voltage divider network at the output terminal of the electric field power extraction module 101. Specifically, the first resistor voltage divider network is used to sample the actual output voltage of the electric field power extraction module 101 and output the corresponding first voltage sample value, which is the ratio of the first voltage sample value to the first voltage divider coefficient. V e / k e This is the actual output voltage of the electric field power extraction module 101. It should be noted that the specific process for determining the first voltage division coefficient can be found in the relevant descriptions in subsequent embodiments, and will not be detailed here.

[0066] The temperature correction factor is used to quantify the impact of changes in ambient temperature on power extraction efficiency. The humidity correction factor is used to quantify the impact of changes in ambient humidity on power extraction efficiency. Both the temperature and humidity correction factors can be obtained experimentally. It should be noted that the specific measurement process for the temperature and humidity correction factors can be found in descriptions in related technologies, and will not be detailed in the embodiments of this application.

[0067] In one specific implementation, the processing module 106 can also be used for:

[0068] Based on the current second voltage sampling value and ambient temperature value, the magnetic field power of the transmission line under test at the current moment is calculated using the following formula (2):

[0069] P m = K mp ·( V m / k m ) 2 ·[1+ α T ( T - T 0)]; formula (2)

[0070] in, P m The magnetic field power of the transmission line under test at the current moment is... K mp This is the pre-calibrated second conversion factor between voltage and magnetic field power. V m This is the second voltage sample value at the current moment. k m This is the second partial pressure coefficient. α T This is a temperature correction factor. T The ambient temperature value at the current moment. T 0 represents the calibration temperature.

[0071] The second conversion coefficient between voltage and electromagnetic power can also be measured experimentally.

[0072] It should be understood that the temperature and humidity at which the first and second conversion coefficients are measured experimentally are the calibration temperature and calibration humidity mentioned above, respectively.

[0073] The second voltage divider coefficient can be determined based on the second resistor voltage divider network at the output terminal of the magnetic field power extraction module 102. Specifically, the second resistor voltage divider network is used to sample the actual output voltage of the magnetic field power extraction module 102 and output the corresponding second voltage sample value, which is the ratio of the second voltage sample value to the second voltage divider coefficient.V m / k m This is the actual output voltage of the magnetic field power extraction module 102. It should be noted that the specific process for determining the second voltage divider coefficient can be found in the relevant descriptions in subsequent embodiments, and will not be detailed here.

[0074] In one specific implementation, the processing module 106 can also be used for:

[0075] A fast Fourier transform is performed on the current detection value sequence within the current power frequency cycle to obtain the frequency domain component sequence corresponding to the current detection value sequence. The fundamental amplitude and multiple harmonic amplitudes of the current detection signal within the current power frequency cycle are determined from the frequency domain component sequence. Based on the fundamental amplitude and all harmonic amplitudes, the total harmonic distortion rate of the current detection signal within the current power frequency cycle is calculated.

[0076] The current detection value sequence consists of all current detection values ​​within the current power frequency cycle. It should be understood that performing a Fast Fourier Transform on the current detection value sequence (i.e., all current detection values) within the current power frequency cycle yields the frequency domain component corresponding to each current detection value within the current power frequency cycle, and the frequency domain component sequence consists of all frequency domain components within the current power frequency cycle. It should be understood that the value of each frequency domain component is a complex number, which is used to describe the amplitude and phase information of the corresponding frequency domain component.

[0077] For example, the processing module 106 can perform modulus-taking and normalization processing on each frequency component in the frequency component sequence to obtain the amplitude of each frequency component; and determine the amplitude of the frequency component corresponding to the fundamental wave as the fundamental wave amplitude of the current detection signal in the current power frequency cycle; and determine the amplitude of the frequency component corresponding to each harmonic as the harmonic amplitude of the current detection signal in the current power frequency cycle. The amplitude of the frequency component is used to quantify the magnitude of the sinusoidal wave component at the corresponding frequency in the original current detection signal.

[0078] After obtaining the fundamental amplitude and harmonic amplitudes of the current detection signal in the current power frequency cycle, the processing module 106 can calculate the total harmonic distortion rate of the current detection signal in the current power frequency cycle using the following formula (3):

[0079] ;Formula (3)

[0080] in, THD The total harmonic distortion (THD) of the current detection signal within the current power frequency cycle. I 1 represents the fundamental amplitude of the current detection signal within the current power frequency cycle. I 2~ I nThese represent the amplitude values ​​of each harmonic of the current detection signal within the current power frequency cycle.

[0081] In one specific implementation, the processing module 106 can also be used for:

[0082] Based on all current detection values ​​within the current power frequency cycle, determine the target current detection point corresponding to the current peak value within the current power frequency cycle and the peak region corresponding to the target current detection point. Calculate the proportion of current detection points within the peak region whose current detection values ​​are greater than a preset current threshold to all current detection points within the peak region, and determine this proportion as the waveform flat-top ratio of the current detection signal within the current power frequency cycle.

[0083] The preset current threshold is less than the peak current and greater than 95% of the peak current.

[0084] The peak region corresponding to the target current detection point can be: a time region extending to the left and right sides for a certain duration from the target current sampling point.

[0085] The preset current threshold is a critical current value used to define whether the top of the waveform is a flat region.

[0086] In one specific implementation, the processing module 106 can also be used for:

[0087] Determine the effective value and peak value of the current within the current power frequency cycle, and determine the ratio of the peak value to the effective value of the current as the crest factor of the current detection signal within the current power frequency cycle.

[0088] The effective current value in the previous power frequency cycle can be the root mean square of all current detection values ​​in the current power frequency cycle. The peak current value in the previous power frequency cycle can refer to the maximum current detection value in the previous power frequency cycle.

[0089] In one specific implementation, the processing module 106 can also be used for:

[0090] If the waveform flattening rate is greater than the preset flattening rate threshold, the current system operating condition is determined to be the sensor current sensing saturation condition.

[0091] If the current system operating condition is not in the sensor current saturation condition, and the total harmonic distortion rate is greater than the preset distortion rate threshold or the crest factor is greater than the preset factor threshold, then the current system operating condition is determined to be the induced current distortion condition.

[0092] If the current system is not in a state of sensor current saturation or induced current distortion, calculate the energy ratio of electric field power to magnetic field power. If the energy ratio is greater than a first ratio threshold and the electric field power is greater than a first power threshold, determine the current system operating condition as a light-load condition for the transmission line. If the energy ratio is less than a second ratio threshold, determine the current system operating condition as an overload condition for the transmission line. If the energy ratio is greater than or equal to the second ratio threshold and less than or equal to the first ratio threshold, determine the current system operating condition as a normal load condition for the transmission line.

[0093] The preset flat-top ratio threshold is used to describe the maximum flat-top ratio that the waveform of the current detection signal can tolerate. For example, the preset flat-top ratio threshold can range from 20% to 30%.

[0094] The preset distortion rate threshold is used to describe the maximum harmonic contamination value that the waveform of the current detection signal can tolerate. For example, the preset distortion rate threshold can range from 5% to 10%.

[0095] A preset factor threshold can be used to describe the maximum peak value that the waveform of the current detection signal can tolerate. For example, the preset factor threshold can be in the range of 2.0 to 2.5.

[0096] The first ratio threshold can be used to describe the maximum energy ratio of electric field power to magnetic field power under normal load conditions of a transmission line, and the second ratio threshold can be used to describe the minimum energy ratio of electric field power to magnetic field power under normal load conditions of a transmission line. For example, the value range of the first ratio threshold can be 1.5 to 2.5, and the value range of the second ratio threshold can be 0.3 to 0.6.

[0097] The first power threshold is used to describe the minimum electric field power required for the wireless current sensor to function properly.

[0098] Optionally, the processing module 106 can use the formula R = P e / ( P m + δ Calculate the energy ratio of electric field power to magnetic field power. Wherein, R Energy ratio P e Electric field power P m For magnetic field power, δ It is a very small positive number used to ensure that the denominator in the formula is not zero.

[0099] To further illustrate the technical solutions provided in the embodiments of this application, Figure 2A schematic diagram of a wireless current sensor according to another embodiment of this application is also shown. For ease of explanation, only the parts relevant to the embodiments of this application are shown.

[0100] like Figure 2 As shown, the electric field power extraction module 101 may include an electric field coupler 1011, a first voltage doubler rectifier circuit 1012, and a first voltage sampling circuit 1013. The electric field coupler 1011 is used to couple its electric field with the transmission line 20 under test to extract electrical energy from the alternating electric field surrounding the transmission line 20. The extracted electrical energy is rectified by the first voltage doubler rectifier circuit 1012 and output as a first direct current to the energy storage module 103. For example, the electric field coupler 1011 may be a barrel-shaped ion capacitor.

[0101] The first voltage sampling circuit 1013 can be used to acquire the actual output voltage of the electric field power extraction module 101 and output the corresponding first voltage sampling value to the processing module 106. It should be understood that the first voltage sampling circuit 1013 is the aforementioned first resistor voltage divider network. For example, the first voltage sampling circuit 1013 may include a first resistor R1 and a second resistor R2, which can be connected in series between the output terminal of the first voltage doubler rectifier circuit 1012 and ground. Based on this, the aforementioned first voltage divider coefficient can be... r 2 / ( r 1+ r 2), where, r 1 represents the resistance value of the first resistor R1. r 2 represents the resistance value of the second resistor R2.

[0102] like Figure 2 As shown, the magnetic field power harvesting module 102 may include a magnetic field coupler 1021, a second voltage doubler rectifier circuit 1022, and a second voltage sampling circuit 1023. The magnetic field coupler 1021 is used to magnetically couple with the transmission line 20 under test to harvest electrical energy from the alternating magnetic field surrounding the transmission line 20. The harvested electrical energy is rectified by the second voltage doubler rectifier circuit 1022 and output as a second direct current to the energy storage module 103. For example, the magnetic field coupler 1021 may be a current transformer or a Rogowski coil, etc.

[0103] It should be understood that the second voltage sampling circuit 1023 is the aforementioned second resistor voltage divider network. For example, the second voltage sampling circuit 1023 may include a third resistor R3 and a fourth resistor R4, which can be connected in series between the output terminal of the second voltage doubler rectifier circuit 1022 and ground. Based on this, the aforementioned second voltage divider coefficient can be... r 4 / ( r 3+ r 4), of which, r 3 represents the resistance value of the third resistor R3.r 4 represents the resistance value of the fourth resistor, R4.

[0104] like Figure 2 As shown, the current detection module 104 may include a current transformer 1041, a Rogowski coil 1042, a first electronic switch 1043, a second electronic switch 1044, and a signal conditioning circuit 1045. The current transformer 1041 can be connected to the input terminal of the signal conditioning circuit 1045 via the first electronic switch 1043, and the Rogowski coil 1042 can be connected to the input terminal of the signal conditioning circuit 1045 via the second electronic switch 1044. The current transformer 1041 and the Rogowski coil 1042 can be used to sense the current in the transmission line 20 under test and output the corresponding induced current signal to the signal conditioning circuit 1045.

[0105] For example, the signal conditioning circuit 1045 may include a current sampler, a variable gain amplifier, and a filter, etc., for sampling, amplifying, and filtering the induced current signal to output a current detection value to the processing module 106. The current detection value can be used to describe the magnitude of the current in the transmission line 20 under test.

[0106] Optionally, the processing module 106 can control the gain of the variable gain amplifier or the sampling frequency of the current sampler according to the system operating conditions.

[0107] Based on this, in a specific implementation, the processing module 106 can also be used for:

[0108] When the current system is in the sensor current sensing saturation condition, the control current detection module 104 switches from the current transformer mode to the Rogowski coil mode, and marks the current detection value output by the current detection module 104 as unreliable. The current magnitude of the current of the transmission line under test is estimated according to the electric field-assisted current estimation model to obtain the corresponding current estimation value.

[0109] Under the current system operating condition of induced current distortion, the control current detection module performs current detection based on a high sampling rate mode.

[0110] Under the current system operating condition of light load on the transmission line, the control current detection module uses a high-gain mode to process the induced current signal of the current detection module, uses electric field power to verify the current detection value, and corrects the successfully verified current detection value based on the ambient temperature value.

[0111] Under the current system operating condition of power transmission line overload, the control current detection module uses low gain mode to process the current detection value and corrects the current detection value based on the ambient temperature value.

[0112] Under the current system operating conditions of normal transmission line load, the control current detection module processes the current detection value in medium gain mode and corrects the current detection value based on the ambient temperature value.

[0113] For example, when the current system is in a sensor current sensing saturation state, the processing module 106 can control the current detection module 104 to switch from current transformer mode to Rogowski coil mode by controlling the first electronic switch 1043 to turn off and the second electronic switch 1044 to turn on.

[0114] For example, the electric field-assisted current estimation model can be trained using a deep learning algorithm based on a preset sample set. The preset sample set can include multiple sample data points, each of which can include an electric field power collected by the wireless current sensor during normal operation and a corresponding transmission line current value. When training the electric field-assisted current estimation model, the electric field power in each sample data point can be used as the model input, and the transmission line current value in each sample data point can be used as the model output, thereby enabling the electric field-assisted current estimation model to learn the correspondence between the electric field power and the transmission line current value. Based on this, the processing module 106 can input the electric field power of the transmission line 20 to be measured at the current moment into the electric field-assisted current estimation model for processing, thereby obtaining the corresponding current estimation value, which is the current detection value under the corresponding system operating condition.

[0115] For example, the current sampler in the signal conditioning circuit 1045 of the current detection module 104 can have a high sampling rate mode and a low sampling rate mode. The current detection frequency in the high sampling rate mode is higher than the current detection frequency in the low sampling rate mode. Based on this, when the current system operating condition is an induced current distortion condition, the processing module 106 can control the current sampler to switch to the high sampling rate mode, so that the current detection module performs current detection based on the high sampling rate mode.

[0116] For example, the variable gain amplifier in the signal conditioning circuit 1045 of the current detection module 104 can have a high-gain mode, a medium-gain mode, and a low-gain mode. The gain in the high-gain mode is greater than the gain in the medium-gain mode, and the gain in the medium-gain mode is greater than the gain in the low-gain mode. Based on this, when the current system operating condition is a light-load condition for the transmission line, the processing module 106 can control the variable gain amplifier to switch to high-gain mode, so that the current detection module 104 amplifies the induced current signal with a higher gain. Furthermore, to improve current detection accuracy, the processing module 106 can also input the electric field power of the transmission line 20 under test at the current moment into the aforementioned electric field-assisted current estimation model for processing, obtaining the corresponding current estimation value, and verifying the current detection value based on this current estimation value. For example, if the difference between the current detection value and the current estimation value is less than a preset difference threshold, the processing module 106 can determine that the verification is successful; if the difference between the current detection value and the current estimation value is greater than or equal to the preset difference threshold, the processing module 106 can determine that the verification fails.

[0117] It should be noted that the specific process of verifying the current detection value based on the ambient temperature value can be found in the description in the relevant technology, and will not be described in detail in the embodiments of this application.

[0118] For example, when the current system operating condition is a power transmission line overload condition, the processing module 106 can control the variable gain amplifier to switch to a low gain mode, so that the current detection module 104 amplifies the induced current signal with a lower gain. When the current system operating condition is a power transmission line normal load condition, the processing module 106 can control the variable gain amplifier to switch to a medium gain mode, so that the current detection module 104 amplifies the induced current signal with a moderate gain. This enables the wireless current sensor to have high current detection accuracy under all operating conditions.

[0119] As can be seen, the wireless current sensor provided in this application embodiment is equipped with both an electric field power extraction module and a magnetic field power extraction module. The two power extraction modules can complement each other under different operating conditions, thus enabling the wireless current sensor to have high stability under all operating conditions. Since the processor can identify the current system operating condition and control the current detection module to use a current detection strategy that matches the current system operating condition for current detection, the wireless current sensor can have high current detection accuracy under all operating conditions.

[0120] Optionally, in other embodiments, to ensure sufficient energy storage in the energy storage module while reducing the power consumption of the current sensor, the energy storage module 103 may specifically include a third electronic switch, a fourth electronic switch, and an energy storage capacitor (not shown). The electric field power extraction module 101 can be connected to the positive terminal of the energy storage capacitor via the third electronic switch, and the magnetic field power extraction module 102 can be connected to the positive terminal of the energy storage capacitor via the fourth electronic switch. The negative terminal of the energy storage capacitor can be grounded. The switching on or off of the third and fourth electronic switches can both be controlled by the processing module 106.

[0121] Based on this, the processing module 106 can also be used to: obtain the remaining power of the energy storage module 103 at the current moment, and calculate the energy efficiency index of the electric field power extraction module 101 according to the remaining power of the energy storage module 103 at the current moment, the electric field power of the transmission line under test at the current moment, the ambient temperature value at the current moment, the ambient humidity value at the current moment, and the calibration temperature, using the following formula (4):

[0122] ;Formula (4)

[0123] in, EBI e-field The energy efficiency index of the electric field power extraction module 101, w e As the fundamental weight of the electric field, P e The electric field power of the transmission line under test at the current moment is... T The ambient temperature value at the current moment. T 0 represents the calibration temperature. α H This is the humidity correction factor. H The current ambient humidity value. C remain This represents the remaining power of the energy storage module 103 at the current moment. w c As a weight for penalties related to energy storage risks, R rick As a risk factor.

[0124] electric field fundamental weights w e It can be obtained through experimental measurement. For example, the fundamental weight of the electric field. w e Specifically, this can be achieved by measuring the first maximum power that the electric field power extraction module 101 can generate under an ideal, controlled laboratory environment. P emax The second maximum power that the magnetic field power extraction module 102 can generate P mmax and willP emax / ( P emax + P mmax ) is determined as the fundamental weight of the electric field w e .

[0125] For example, energy storage risk penalty weight w c It can be dynamically adjusted based on the current system operating conditions. For example, its functions can be selected when the current system operating conditions are light-load or normal-load conditions of the transmission line, and the energy storage risk penalty weight can be adjusted accordingly. w c The value can be 0, in which case no risk penalty is applied; under the current system operating condition of induced current distortion, the energy storage risk penalty weight is... w c The value can be 0.5; under the current operating condition of sensor current saturation, the energy storage risk penalty weight... w c The value of can be 1.

[0126] For example, risk factors R rick It can be calculated according to the following formula (5):

[0127] R rick =max(THD, pdl / pdl th ); formula (5)

[0128] in, THD The total harmonic distortion (THD) of the current detection signal within the current power frequency cycle. pdl This represents the waveform flat-top ratio of the current detection signal within the current power frequency cycle. pdl th This is the preset flat-top ratio threshold.

[0129] The processing module 106 can also be used to: calculate the energy efficiency index of the magnetic field power extraction module 102 based on the remaining power of the energy storage module 103 at the current time, the magnetic field power of the transmission line under test at the current time, the ambient temperature value at the current time, the calibration temperature, and the ambient humidity value at the current time, using the following formula (6):

[0130] ;Formula (6)

[0131] in, EBI m-field The energy efficiency index of the magnetic field power extraction module 102; w mThe magnetic field base weight is used to balance the initial benefits of the magnetic field power extraction module 102; P m The magnetic field power of the transmission line to be measured at the current moment; β 1 is the basic loss factor. β 2 represents the temperature sensitivity coefficient, and r represents the temperature decay rate. T The ambient temperature value at the current moment. T 0 represents the calibration temperature; C remain This represents the remaining power of the energy storage module 103 at the current moment.

[0132] Magnetic field fundamental weight w m It can be obtained through experimental measurement. For example, the fundamental weight of a magnetic field. w m The first maximum power that the electric field power harvesting module 101 can generate can be obtained in an ideal, controlled laboratory environment by means of the following method: P emax The second maximum power that the magnetic field power extraction module 102 can generate P mmax and will P mmax / ( P emax + P mmax ) is determined as the fundamental weight of the magnetic field. w m .

[0133] Basic loss coefficient β 1 can be used to describe the inherent minimum power loss of the magnetic field power extraction module 102 at a rated temperature. Temperature sensitivity coefficient. β 2 can be used to describe the sensitivity of the power loss of the magnetic field power extraction module 102 to the deviation of the current temperature value from the calibrated temperature. Temperature decay rate r This can be used to describe the exponential increase in power loss of the magnetic field power extraction module 102 as temperature deviates. These three factors together constitute the nonlinear temperature loss term in formula (6). This is used to ensure the accuracy of the energy efficiency index calculation for the magnetic field power extraction module 102. For example, the base loss factor... β 1. Temperature sensitivity coefficient β 2 and temperature decay rate r All of these can be obtained through experimental measurement.

[0134] Based on this, the processing module 106 can also be used to calculate the difference between the energy efficiency index of the electric field power extraction module 101 and the energy efficiency index of the magnetic field power extraction module 102, and when the difference is less than the preset efficiency threshold, control the third electronic switch and the fourth electronic switch to be turned on, so that the energy storage module 103 can simultaneously obtain electrical energy from the electric field power extraction module 101 and the magnetic field power extraction module 102.

[0135] Specifically, the processing module 106 can also be used to, when the above difference is greater than or equal to a preset benefit threshold, if the energy efficiency index of the electric field power extraction module 101 is greater than the energy efficiency index of the magnetic field power extraction module 102, control the third electronic switch to be turned on and the fourth electronic switch to be turned off, so that the energy storage module 103 obtains electrical energy only from the electric field power extraction module 101; if the energy efficiency index of the electric field power extraction module 101 is less than the energy efficiency index of the magnetic field power extraction module 102, control the third electronic switch to be turned off and the fourth electronic switch to be turned on, so that the energy storage module 103 obtains electrical energy only from the magnetic field power extraction module 102.

[0136] As can be seen from the above, this embodiment adopts a method based on... EBI The model's intelligent power supply scheduling ensures uninterrupted operation and minimized power consumption of the current sensor under all operating conditions.

[0137] This application also provides a current detection method, applied to the wireless current sensor described in any of the foregoing embodiments, for implementing the function of the processing module in the wireless current sensor.

[0138] This application also provides a computer program product, including a computer program that, when run, implements the function of the processing module in the wireless current sensor as described in any of the foregoing embodiments.

[0139] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, refer to the relevant descriptions of other embodiments.

[0140] It should be noted that, unless otherwise specified, all technical terms used in the embodiments of this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The technical terms used in the embodiments of this application are only used to explain specific embodiments of this application and are not intended to limit this application.

[0141] The term "embodiment" as used in the description of embodiments in this application means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0142] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0143] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 this application, and should all be included within the protection scope of this application.

Claims

1. A wireless current sensor, characterized by The power supply module comprises an electric field power supply module, a magnetic field power supply module, an energy storage module, a current detection module, an environment sensing module, a processing module and a wireless communication module. The electric field power supply module is configured to couple with a to-be-tested power transmission line through an electric field to obtain electric energy from an alternating electric field around the to-be-tested power transmission line and output first direct current to the energy storage module and output a first voltage sampling value to the processing module. The magnetic field power supply module is configured to couple with the to-be-tested power transmission line through a magnetic field to obtain electric energy from an alternating magnetic field around the to-be-tested power transmission line and output second direct current to the energy storage module and output a second voltage sampling value to the processing module. The energy storage module is configured to store electric energy provided by the first direct current and / or the second direct current and provide operating voltage for the current detection module, the environment sensing module, the processing module and the wireless communication module. The current detection module is configured to couple with the to-be-tested power transmission line through a magnetic field to detect current of the to-be-tested power transmission line and output a corresponding current detection value to the processing module, so that the processing module sends the current detection value to an upper computer through the wireless communication module. The environment sensing module is configured to collect an environment temperature value and an environment humidity value and send the environment temperature value and the environment humidity value to the processing module. The processing module is configured to determine electric field power of the to-be-tested power transmission line at a current time according to the first voltage sampling value, the environment temperature value and the environment humidity value at the current time, and determine magnetic field power of the to-be-tested power transmission line at the current time according to the second voltage sampling value and the environment temperature value at the current time. The processing module is configured to determine total harmonic distortion rate, waveform flat top rate and wave crest factor of a current detection signal in a current power frequency cycle. The processing module is configured to determine current system working condition according to the electric field power, the magnetic field power, the total harmonic distortion rate, the waveform flat top rate and the wave crest factor, and control the current detection module to detect current of the to-be-tested power transmission line based on a current detection strategy matched with the current system working condition.

2. The wireless current sensor of claim 1, wherein, The processing module is configured to calculate the electric field power of the to-be-tested power transmission line at the current time according to the first voltage sampling value, the environment temperature value and the environment humidity value at the current time by the following formula: P e = K ep ·( V e / k e )·[1+ α T ( T - T 0)+ α H ( H - H 0)]； wherein, P e is the electric field power of the power transmission line to be measured at the current moment, K ep is a first conversion coefficient between the voltage and the electric field power calibrated in advance, k e is a first voltage division coefficient, V e is the first voltage sampling value at the current moment, α T is a temperature correction coefficient, T is the ambient temperature value at the current moment, T 0 is a calibration temperature, α H is a humidity correction coefficient, H is the ambient humidity value at the current moment, H 0 is a calibration humidity.

3. The wireless current sensor of claim 1, wherein, The processing module is configured to calculate the magnetic field power of the to-be-tested power transmission line at the current time according to the second voltage sampling value and the environment temperature value at the current time by the following formula: P m = K mp ·( V m / k m ) 2 ·[1+ α T ( T - T 0)]； wherein, P m is a magnetic field power of the to-be-tested power transmission line at the current moment, K mp is a second conversion coefficient between the voltage and the magnetic field power pre-calibrated, V m is the second voltage sampling value at the current moment, k m is a second voltage division coefficient, α T is a temperature correction coefficient, T is the ambient temperature value at the current moment, T 0 is a calibration temperature.

4. The wireless current sensor of claim 1, wherein, The processing module is configured to perform fast Fourier transform on a current detection value sequence in the current power frequency cycle to obtain a frequency domain component sequence corresponding to the current detection value sequence, determine fundamental wave amplitude and a plurality of harmonic amplitudes of the current detection signal in the current power frequency cycle from the frequency domain component sequence, and calculate the total harmonic distortion rate of the current detection signal in the current power frequency cycle according to the fundamental wave amplitude and all the harmonic amplitudes.

5. The wireless current sensor of claim 1, wherein, The processing module is specifically configured to: determine a target current detection point corresponding to a current peak value in a current power frequency cycle and a peak value region corresponding to the target current detection point according to all the current detection values in the current power frequency cycle, and calculate a proportion of current detection points in the peak value region where the current detection values are greater than a preset current threshold in all current detection points in the peak value region, and determine the proportion as a waveform flat top rate of the current detection signal in the current power frequency cycle; and the preset current threshold is less than the current peak value and greater than 95% of the current peak value.

6. The wireless current sensor of claim 1, wherein, The processing module is specifically configured to: determine a current effective value and a current peak value in a current power frequency cycle, and determine a ratio of the current peak value to the current effective value as a wave crest factor of the current detection signal in the current power frequency cycle.

7. The wireless current sensor of any one of claims 1-6, wherein, The processing module is specifically configured to: determine that the current system condition is a sensor current induction saturation condition when the waveform flat top rate is greater than a preset flat top rate threshold; determine that the current system condition is an induced current distortion condition when the total harmonic distortion rate is greater than a preset distortion rate threshold or the wave crest factor is greater than a preset factor threshold while the current system condition is not in the sensor current induction saturation condition; calculate an energy ratio of the electric field power to the magnetic field power when the current system condition is not in the sensor current induction saturation condition or the induced current distortion condition; determine that the current system condition is a power transmission line light load condition when the energy ratio is greater than a first ratio threshold and the electric field power is greater than a first power threshold; determine that the current system condition is a power transmission line overload condition when the energy ratio is less than a second ratio threshold; determine that the current system condition is a power transmission line normal load condition when the energy ratio is greater than or equal to the second ratio threshold and less than or equal to the first ratio threshold.

8. The wireless current sensor of claim 7, wherein, The processing module is specifically configured to: control the current detection module to switch from a current transformer mode to a Rogowski coil mode and mark the current detection values output by the current detection module as being unreliable when the current system condition is the sensor current induction saturation condition, and estimate the current of the power transmission line to be measured according to an electric field auxiliary current to obtain corresponding current estimation values; control the current detection module to perform current detection based on a high sampling rate mode when the current system condition is the induced current distortion condition; control the current detection module to adopt a high gain mode to process an induced current signal of the current detection module and use the electric field power to verify the current detection values and correct the current detection values that pass the verification based on the ambient temperature value when the current system condition is the power transmission line light load condition; control the current detection module to adopt a low gain mode to process the current detection values and correct the current detection values based on the ambient temperature value when the current system condition is the power transmission line overload condition. In a case where the current system working condition is a normal load working condition of the power transmission line, the current detection module is controlled to process the current detection value in a medium gain mode, and the current detection value is corrected based on the ambient temperature value.

9. A current detection method characterized by, The current detection method is applied to the wireless current sensor as claimed in any one of claims 1-8 to realize the function of the processing module in the wireless current sensor.

10. A computer program product, characterised in that, The computer program is included, and the computer program is run to realize the current detection method as claimed in claim 9.

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