CN109655654B - High-current measurement method and device based on bypass shunt technology - Google Patents

Abstract

The utility model provides a large current measuring method and device based on bypass shunt technology, the device comprises a main conductor, a shunt conductor, a current transformer, a temperature sensor and a processor, the device connects the main conductor and the shunt conductor in parallel and then strings into a current loop, and then the transformer is used for sampling the current of the shunt conductor loop, so as to realize the conversion from large current measurement to small current measurement; the method includes switching the high current measurement device into a circuit loop, further comprising: performing intensive discrete shunt experiments to form an experiment engineering database; and calculating a loop current value according to the current value detected by the high-current measuring device and the experimental engineering database. According to the utility model, the influence of external temperature and conductor temperature rise on the conductor resistivity is comprehensively considered, the influence of the temperature rise on the shunt conductor is reduced, the reliability is higher, the error is smaller, the size of the transformer is reduced to a great extent, the measurement dynamic range is improved, the easy saturation of the transformer is reduced, and the purpose of better measurement is achieved.

Description

High-current measurement method and device based on bypass shunt technology

Technical Field

The utility model relates to the technical field of heavy current measurement, in particular to a heavy current measurement method and device based on bypass shunt technology.

Background

With the development of current detection technology, more and more high-current measurement methods have been developed. The current common high-current detection method is a resistive shunt method and a mutual inductor sampling method. The resistive shunt method is to measure the current by using a resistive shunt device such as a precision alloy resistor, a manganese nickel copper alloy resistor rod, a copper strip and the like in a series connection mode by applying ohm law, and has the advantages of high precision and low deviation, and the defects of being incapable of providing power insulation and low temperature drift, and having larger power consumption on the resistor, increasing temperature and possibly burning the device due to transient peak current fluctuation when measuring large current. The mutual inductor sampling method belongs to a detection method based on a magnetic field, and the detection method has the advantages of good isolation, low power loss and the like, so that the mutual inductor sampling method is widely applied to the fields of driving technology and large current, but has the defects of large volume, narrow dynamic range, easy saturation, and unsatisfactory compensation characteristic, linearity and temperature characteristic.

The utility model patent with application number 200920010019.9 discloses an electronic control device for detecting large current by using a small current transformer, which utilizes the existing zero sequence current transformer, residual current transformer and other small current transformers to detect large current, and uses a load wire which is parallel to a load wire with very thin and very short impedance wire to play a role of proportional shunt, and is matched with an electronic control circuit with high sensitivity to output a protection signal. However, since a large current causes an increase in the load temperature, the device of the present utility model does not consider the influence of temperature on the load resistance value, and the measurement accuracy of the large current is not high.

The utility model patent with the application number of 201620763677.5 discloses a high-current measuring circuit with temperature compensation in a high-temperature environment, which comprises a thermocouple temperature measuring module, a step voltage measuring module, an MCU communication and ADC sampling module, an RS485 transmission conversion module, a power module and an upper computer, wherein the MCU communication and ADC sampling module is respectively connected with the thermocouple temperature measuring module and the step voltage measuring module through ADC sampling ports, a serial port transmitting end of the MCU communication and ADC sampling module is connected with a serial port receiving end of the RS485 transmission conversion module, the RS485 transmission conversion module is connected with the upper computer through the serial port transmitting end, and the power module supplies voltage conversion and high-precision low-temperature elegant after the voltage conversion and the high-precision low-temperature elegant conversion to the MCU communication and ADC sampling module. The circuit realizes a high-current measurement technology with a temperature compensation function in a high-temperature environment, improves the measurement accuracy and measurement instantaneity of high current, and has the advantages of reliable data transmission, low cost and easiness in implementation. However, when considering the relationship between the resistance and the temperature, it is assumed that the relationship between the temperature and the resistance is linear, but in reality, the relationship between the temperature and the resistance is not strictly linear, and factors affecting the resistance include not only the resistance temperature but also the current flowing through the resistance, the ambient temperature, and the conductor material, and therefore, the accuracy of the present utility model needs to be further improved.

Disclosure of Invention

In order to solve the technical problems, the utility model provides a high-current measuring method and device based on a bypass shunt technology, which comprehensively consider various factors influencing the resistance of a conductor and have higher measuring precision on high current.

A high-current measurement method based on bypass shunt technology comprises the following steps: the high-current measuring device is connected into the circuit loop, and the method further comprises the following steps:

performing intensive discrete shunt experiments to form an experiment engineering database;

and calculating a loop current value according to the current value detected by the high-current measuring device and the experimental engineering database.

Preferably, the high current measuring device comprises a main conductor, a shunt conductor, a current transformer, a temperature sensor and a processor.

Any of the above-described solutions is preferred in that the main conductor is fixedly connected with the shunt conductor in parallel, the main conductor being connected in series to the circuit loop.

In any of the above aspects, preferably, the current transformer is connected to the shunt conductor, and is configured to collect a current value in the shunt conductor.

Preferably, any of the above aspects, the temperature sensor includes a main conductor temperature sensor, a shunt conductor temperature sensor, and an ambient temperature sensor.

Preferably, in any of the above aspects, the dominant body temperature sensor is fixed in contact with the dominant body for detecting the dominant body temperature.

In any of the above aspects, preferably, the shunt conductor temperature sensor is fixed in contact with the shunt conductor, and is configured to detect the shunt conductor temperature.

Preferably, in any of the above schemes, the ambient temperature sensor is used for detecting ambient temperature, and is arranged far away from the main conductor and the shunt conductor, and is fully contacted with external ambient air, so that the influence of conductor temperature rise on the sensor is reduced.

In any of the above embodiments, it is preferable that the temperature sensor and the current transformer are connected to the processor.

In any of the above embodiments, preferably, the main conductor is a metal conductor with uniform material, and the shunt conductor is the same or different from the main conductor.

In any of the above aspects, it is preferable that the shunt ratio of the shunt conductor to the main conductor is changed by adjusting at least one of the shape, length, cross-sectional area, and material of the shunt conductor.

Preferably, in any of the above aspects, the apparatus for performing dense discrete shunt experiments comprises: a heavy current generator, a temperature instrument, a current transformer, a loop resistance tester and a recording tool.

Preferably, in any of the above schemes, the step of performing intensive discrete shunt experiments to form an experimental engineering database includes the steps of:

s11, selecting a main conductor and a shunt conductor;

s12, connecting the main conductor and the shunt conductor in parallel, and then connecting the main conductor and the shunt conductor with a high-current generator to form a circuit loop;

s13, setting a large current generator to generate a fixed current value;

s14, after detecting that the temperature of the main conductor reaches a steady-state temperature, sampling a current value of the shunt conductor;

s15, measuring the electrical impedance value of the main conductor;

s16, recording data, including the material quality, the conductor outline dimension, the conductor steady-state temperature, the environment temperature, the current generated by the heavy current generator, the current value and the shunt ratio of the main conductor and the shunt conductor, the electrical impedance value of the main conductor and the shunt conductor and the compensation coefficient determined by the data;

s17, changing a fixed current value generated by the heavy current generator, and repeating the steps S14-S16;

s18, changing the main conductor and/or the shunt conductor, and repeating the steps S11-S17;

s19, forming the recorded data into an experimental engineering database.

Either of the above-described schemes is preferred, for the same main conductor and shunt conductor combination, the current value generated by the high current generator should be in the range of 3000A and sampled multiple times within that range.

In any of the above aspects, in step S14, the current transformer is preferably connected to the shunt conductor, and the shunt conductor current value is sampled.

In any of the above embodiments, in step S14, the temperature meter is preferably disposed on the main conductor, and the change in the dominant temperature is preferably detected.

In any of the above embodiments, it is preferable that in step S15, the main conductor electrical impedance value is measured using a loop resistance tester.

In any of the above embodiments, it is preferable that in step S16, the ambient temperature is measured using a temperature meter.

In any of the above embodiments, in step S16, the conductor external dimension preferably includes a conductor length and a cross-sectional area.

Any of the above-described schemes preferably uses the recording tool to record data from a dense discrete shunt experiment.

In any of the above aspects, it is preferable that the loop current value is calculated based on the current value detected by the high current detection device and the experimental engineering database, and the method includes the steps of:

s31: detecting a current value of a shunt conductor by a current transformer;

s32: searching compensation coefficients in the experimental engineering database according to the materials of the main conductor and the shunt conductor, the outline dimension of the conductor, the temperature rise of the conductor and the environmental temperature;

s33: and carrying the searched compensation coefficient, the conductor size and the temperature rise into a shunt formula, and calculating the shunt ratio to obtain the loop current value.

In any of the above schemes, it is pre-selected in step S23 that the split formula is:

wherein I represents the total current of the circuit loop, I₁ Representing the current split by the split conductor, ρ₁ 、ρ₀ 、T₁ 、L₁ 、S₁ 、α₁ The resistivity, the resistivity at 0 ℃, the steady-state temperature, the length, the cross-sectional area and the compensation coefficient of the shunt conductor are respectively; ρ₂ 、ρ₀ ′、T₂ 、L₂ 、S₂ 、α₂ The main resistivity, the resistivity at 0 ℃, the steady-state temperature, the length, the cross-sectional area and the compensation coefficient, respectively.

Another aspect of the utility model provides a high current measurement device based on bypass shunt technology, comprising a main conductor, a shunt conductor, a current transformer, a temperature sensor and a processor.

Any of the above-described solutions is preferred in that the main conductor is fixedly connected with the shunt conductor in parallel, the main conductor being connected in series to the circuit loop.

In any of the above aspects, preferably, the current transformer is connected to the shunt conductor, and is configured to collect a current value in the shunt conductor.

Preferably, any of the above aspects, the temperature sensor includes a main conductor temperature sensor, a shunt conductor temperature sensor, and an ambient temperature sensor.

Preferably, in any of the above aspects, the dominant body temperature sensor is fixed in contact with the dominant body for detecting the dominant body temperature.

In any of the above aspects, preferably, the shunt conductor temperature sensor is fixed in contact with the shunt conductor, and is configured to detect the shunt conductor temperature.

Preferably, in any of the above schemes, the ambient temperature sensor is used for detecting ambient temperature, and is arranged far away from the main conductor and the shunt conductor, and is fully contacted with external ambient air, so that the influence of conductor temperature rise on the sensor is reduced.

In any of the above embodiments, it is preferable that the temperature sensor and the current transformer are connected to the processor.

In any of the above embodiments, preferably, the main conductor is a metal conductor with uniform material, and the shunt conductor is the same or different from the main conductor.

In any of the above aspects, it is preferable that the shunt ratio of the shunt conductor to the main conductor is changed by adjusting at least one of the shape, length, cross-sectional area, and material of the shunt conductor.

In any of the above schemes, preferably, the processor is provided with the experimental engineering database, and the compensation coefficient is searched in the experimental engineering database according to the material of the main conductor, the shunt conductor, the outline dimension of the conductor, the conductor temperature rise and the environmental temperature, the shunt ratio is calculated, and then the loop current value is calculated according to the current value in the shunt conductor collected by the current transformer.

The high-current measuring method based on the bypass shunt technology comprehensively considers the influence of external temperature and conductor temperature rise on the conductor resistivity, the device connects the main conductor and the shunt conductor in parallel and then strings the main conductor and the shunt conductor into a current loop, and then a transformer is used for sampling the current of the shunt conductor loop, so that the high-current measurement is converted into the low-current measurement. The utility model not only reduces the influence of temperature rise on the shunt conductor, has higher reliability and smaller error, but also reduces the size of the transformer to a great extent, improves the measurement dynamic range, reduces the easy saturation of the transformer and achieves the purpose of better measurement.

Drawings

Fig. 1 is a flow chart of a preferred embodiment of a high current measurement method based on bypass shunt technology according to the present utility model.

Fig. 2 is a flow chart of a preferred embodiment of performing intensive discrete shunt experiments to form an experimental engineering database according to the embodiment of fig. 1 of the high current measurement method based on the bypass shunt technology according to the present utility model.

FIG. 3 is a schematic diagram of a preferred embodiment of the dense discrete shunt experimental setup of the embodiment shown in FIG. 1 according to the high current measurement method based on the bypass shunt technique of the present utility model.

Fig. 4 is a schematic structural view of a preferred embodiment of a high current measuring device based on the bypass shunt technology according to the present utility model.

Detailed Description

The utility model will be described in more detail with reference to specific examples.

Example 1

As shown in fig. 1, a high current measurement method based on bypass shunt technology includes the steps of:

s1, performing intensive discrete shunt experiments to form an experiment engineering database;

s2, connecting the high-current measuring device into a circuit loop;

s3, calculating a loop current value according to the current value detected by the large electric quantity measuring device and the experimental engineering database.

In general, the resistivity of a conductor varies linearly with temperature within a range where the temperature variation is not large, i.e., ρ=ρ₀ (1+at), where t is the temperature in degrees Celsius, ρ₀ The electrical resistivity at 0 ℃ is a temperature coefficient of electrical resistivity, but for a conductor with a large current flowing through, the power consumption on the conductor is high, the temperature rise is changed from a simple linear relationship to a nonlinear relationship, and the temperature rise of the conductor has close relationship with the material of the conductor, the magnitude of the current flowing through the conductor and the fluctuation of the ambient temperature, so that the nonlinear relationship between the electrical resistivity of the conductor and the temperature of the conductor is more complex for the conductor with the large current flowing through. To determine as precisely as possible the relationship between the conductor resistivity and the conductor material, the ambient temperature, the value of the current flowing and the temperature rise of the conductor, intensive discrete shunt experiments were performed.

As shown in fig. 2 and fig. 3, in step S1, the apparatus for performing the intensive discrete shunt experiment includes a large current generator, a temperature instrument, a current transformer, a loop resistance tester and a recording tool, where the temperature instrument includes a main conductor temperature instrument and an ambient temperature instrument, and performs the intensive discrete shunt experiment to form an experimental engineering database, and the specific process is as follows:

s11, selecting a main conductor and a shunt conductor;

s12, connecting the main conductor and the shunt conductor in parallel, and then connecting the main conductor and the shunt conductor with a high-current generator to form a circuit loop; the main conductor is fixedly connected with the main body temperature meter, and is used for collecting the temperature rise condition of the main body in the experimental process, connecting the current transformer with the shunt conductor and detecting the current value passing through the shunt conductor; the environment temperature instrument is far away from the main conductor and is used for monitoring the experimental environment temperature;

s13, setting a large current generator to generate a fixed current value;

s14, after the temperature of the dominant body reaches a steady-state temperature through the temperature meter of the dominant body, sampling a current value of a shunt conductor by using the current transformer;

s15, measuring the electrical impedance value of the main conductor by adopting a loop resistance tester;

s16, recording data by using the recording tool, wherein the data comprise conductor materials, conductor external dimensions (including the length and the sectional area of a conductor), conductor steady-state temperature, environment temperature, current values generated by a large current generator, current values and shunt ratios of a main conductor and a shunt conductor, electrical impedance values of the main conductor and the shunt conductor and compensation coefficients determined by the data;

s17, changing a fixed current value generated by the heavy current generator, and repeating the steps S14-S16;

s18, changing the main conductor and/or the shunt conductor, and repeating the steps S11-S17;

and S19, integrating the recorded data to form an experimental engineering database.

For the same main conductor and shunt conductor combination, the current value generated by the heavy current generator should be in the range of 3000A, and multiple samples are performed within the range, for example, 1A and/or 3A and/or 5A and/or 10A are used as sampling intervals, and experiments are performed. And recording parameters such as temperature rise conditions of different conductor materials under different current values, current values and shunt ratios of the main conductor and the shunt conductor, electrical impedance values of the main conductor and the shunt conductor and the like. Analysis of a large amount of experimental data shows that the conductor temperature rise and the impedance are obviously changed along with the increase of discrete current values and the fluctuation of ambient temperature, and the shunt ratio error is also increased along with the increase of the discrete current values, so that the shunt relation between the shunt conductor and the main conductor is changed from the linear state when the current is low to the nonlinear state when the current is high, the resistances of different conductor materials at different steady-state temperatures are determined according to the experimentally recorded data, the compensation coefficients of different conductors at different steady-state temperatures are further determined, and all recorded data including the compensation coefficients are formed into an experimental engineering database.

The high-current measuring device is connected into the circuit loop to measure the current of the circuit loop. As shown in fig. 4, the device comprises a main conductor, a shunt conductor, a current transformer, a main conductor temperature sensor, a shunt conductor temperature sensor, an ambient temperature sensor and a processor, wherein the main conductor and the shunt conductor are fixedly connected in parallel, the main conductor is connected in series to a circuit loop, the main conductor is a metal conductor with uniform material, and the shunt conductor and the main conductor are made of the same or different materials; the current transformer is connected with the shunt conductor and is used for collecting current values in the shunt conductor; the main body temperature sensor is in contact fixation with the main body and is used for detecting the main body temperature, the shunt conductor temperature sensor is in contact fixation with the shunt conductor and is used for detecting the shunt conductor temperature, the environment temperature sensor is used for detecting the environment temperature, is far away from the main conductor and the shunt conductor and is fully in contact with external environment air, and the influence of conductor temperature rise on the environment temperature sensor is reduced; the main body temperature sensor, the shunt conductor temperature sensor, the environment temperature sensor and the current transformer are all connected with the processor. The processor is provided with the experimental engineering database.

The current transformer sends the collected current value in the shunt conductor to the processor, the main temperature sensor, the shunt conductor temperature sensor and the environment temperature sensor send the collected temperature information to the processor, and the processor searches compensation coefficients in the experimental engineering database according to the received shunt conductor current value and the received temperature information and the materials of the main conductor and the shunt conductor and the overall dimension of the conductor, compensates the resistivity of the main conductor and the shunt conductor, further calculates the shunt ratio, and obtains a loop current value according to the current value in the shunt conductor collected by the current transformer. The said placeThe processor is based on the formulaCalculating the shunt ratio and the loop current value, wherein I represents the total current of the loop, I₁ Representing the current split by the split conductor, ρ₁ 、ρ₀ 、T₁ 、L₁ 、S₁ 、α₁ The resistivity, the resistivity at 0 ℃, the steady-state temperature, the length, the cross-sectional area and the compensation coefficient of the shunt conductor are respectively; ρ₂ 、ρ₀ ′、T₂ 、L₂ 、S₂ 、α₂ The main resistivity, the resistivity at 0 ℃, the steady-state temperature, the length, the cross-sectional area and the compensation coefficient, respectively.

In the process of measuring the large current of the circuit loop, the shunt ratio of the shunt conductor to the main conductor can be changed by adjusting at least one of the shape, the length, the sectional area and the material of the shunt conductor, the large current measurement is converted into the small current measurement, and the current flowing through the shunt conductor is in the range of the measuring range of the current transformer.

Example 2

The high-current measuring method and the device based on the bypass shunt technology can be applied to detection of high current in a medium-low voltage distribution network, and the high-current measuring device based on the bypass shunt technology has the advantages that the main conductor is a metal conductor with uniform material, the impedance and the temperature rise change conditions of the conductor under different current values need to be determined in advance, and the resistivity compensation coefficients under different conditions are determined. When high-current measurement is carried out, the main conductor is connected in series into a power grid loop. Because the current transformer does not need to be transmitted to the main conductor, the shape of the main conductor is not strictly limited, the volume of the measuring device can be reduced to a certain extent, the miniaturization of the measuring device is realized, and the space utilization rate is improved. The shunt conductor is the same material or different materials as the main conductor, is connected in parallel with the main conductor, changes the shunt ratio of the shunt conductor to the main conductor by adjusting at least one of the shape, the length, the sectional area and the material of the shunt conductor, can convert the high-current measurement into the low-current measurement in time as long as the resistance value of the shunt conductor is larger than that of the main conductor by adjusting, and can obtain the current value of the whole power grid loop by directly measuring the low-current in the shunt conductor through the current transformer penetrating the shunt conductor.

It should be noted that the above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; while the foregoing embodiments are illustrative of the present utility model in detail, those skilled in the art will appreciate that: the technical scheme described in the foregoing embodiments may be modified or some or all of the technical features may be replaced with equivalents, which do not depart from the scope of the technical scheme of the present utility model.

Claims (4)

1. A high-current measurement method based on bypass shunt technology comprises the following steps: the high-current measuring device is connected into a circuit loop, and is characterized in that: further comprises:

performing intensive discrete shunt experiments to form an experiment engineering database;

calculating a loop current value according to the current value detected by the high-current measuring device and the experimental engineering database;

the high-current measuring device comprises a main conductor, a shunt conductor, a current transformer, a temperature sensor and a processor, wherein the main conductor and the shunt conductor are fixedly connected in parallel, the main conductor is connected in series to a circuit loop, and the current transformer is connected with the shunt conductor and is used for collecting current values in the shunt conductor;

the device for carrying out the intensive discrete shunt experiment comprises: the device comprises a heavy current generator, a temperature instrument, a current transformer, a loop resistance tester and a recording tool;

performing intensive discrete shunt experiments to form an experiment engineering database, comprising the following steps:

s11, selecting a main conductor and a shunt conductor;

s12, connecting the main conductor and the shunt conductor in parallel, and then connecting the main conductor and the shunt conductor with a high-current generator to form a circuit loop;

s13, setting a large current generator to generate a fixed current value;

s14, after detecting that the temperature of the main conductor reaches a steady-state temperature, sampling a current value of the shunt conductor;

s15, measuring the electrical impedance value of the main conductor;

s16, recording data, including the material quality, the conductor outline dimension, the conductor steady-state temperature, the environment temperature, the current generated by the heavy current generator, the current value and the shunt ratio of the main conductor and the shunt conductor, the electrical impedance value of the main conductor and the shunt conductor and the compensation coefficient determined by the data;

s17, changing a fixed current value generated by the heavy current generator, and repeating the steps S14-S16;

s18, changing the main conductor and/or the shunt conductor, and repeating the steps S11-S17;

s19, forming the recorded data into an experimental engineering database;

according to the current value detected by the heavy current detection device and the experimental engineering database, calculating a loop current value, comprising the following steps:

s31: detecting a current value of a shunt conductor by a current transformer;

s32: searching compensation coefficients in the experimental engineering database according to the materials of the main conductor and the shunt conductor, the outline dimension of the conductor, the temperature rise of the conductor and the environmental temperature;

s33: the searched compensation coefficient, the conductor size and the temperature rise are brought into a shunt formula, and the shunt ratio is calculated to obtain a loop current value;

in step S33, the shunting formula is:wherein I represents the total current of the circuit loop, I₁ Representing shunt conductorsDivided current ρ₁ 、ρ₀ 、T₁ 、L₁ 、S₁ 、α₁ The resistivity, the resistivity at 0 ℃, the steady-state temperature, the length, the cross-sectional area and the compensation coefficient of the shunt conductor are respectively; ρ₂ 、ρ₀ ′、T₂ 、L₂ 、S₂ 、α₂ The main resistivity, the resistivity at 0 ℃, the steady-state temperature, the length, the cross-sectional area and the compensation coefficient, respectively.

2. The bypass shunt technology-based high current measurement method according to claim 1, wherein: the temperature sensor comprises a main conductor temperature sensor, a shunt conductor temperature sensor and an environment temperature sensor.

3. The bypass shunt technology-based high current measurement method according to claim 2, wherein: the main body temperature sensor is fixed in contact with the main body and is used for detecting the main body temperature; the shunt conductor temperature sensor is fixed in contact with the shunt conductor and is used for detecting the temperature of the shunt conductor; the environmental temperature sensor is used for detecting the environmental temperature, is far away from the main conductor and the shunt conductor and is fully contacted with external environmental air, so that the influence of conductor temperature rise on the sensor is reduced.

4. The bypass shunt technology-based high current measurement method according to claim 1, wherein: the main conductor is a metal conductor with uniform material, and the shunt conductor and the main conductor are the same or different in material.