CN111965533B - Residual current calculation method, calculation device, storage medium and detection equipment - Google Patents
Residual current calculation method, calculation device, storage medium and detection equipment Download PDFInfo
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Abstract
The invention discloses a method, a device, a storage medium and a detection device for calculating residual current, wherein the calculating method comprises the following steps: obtaining the residual current at the current moment after filtering; delaying the filtered residual current at the current moment for 1/4 period to obtain an orthogonal coordinate signal of the residual current at the current moment; calculating to obtain an effective value of the residual current according to the residual current at the current moment and the orthogonal coordinate signal of the residual current at the current moment; and calculating a real-time value of the residual current according to the effective value of the residual current. The effective value of the residual current is obtained through calculation of the current residual current and the orthogonal coordinate signal of the current residual current, so that the real-time value of the residual current can be obtained in real time, real-time monitoring data are provided for the action state of residual current protection and an action value cloud platform, the digital requirement of the residual current reclosing circuit breaker is met, and the problem that the real-time residual current value of the residual current reclosing circuit breaker cannot be detected at present is solved.
Description
Technical Field
The invention relates to the technical field of low-voltage electrical appliances, in particular to a method for calculating residual current, a calculating device, a storage medium and detection equipment.
Background
The residual current reclosing circuit breaker is used as equipment for protecting the safety of lives and properties of people in a power distribution system, and the reliability and the rapidity of the protection action of the residual current reclosing circuit breaker directly influence the characteristics of the safety protection function of the residual current reclosing circuit breaker. Under the current major trend of electric power internet of things construction, the residual current value of a residual current protector of a terminal power distribution system needs to be detected in real time. However, the real-time residual current value of the residual current reclosing circuit breaker cannot be detected in the prior art.
Disclosure of Invention
Therefore, the technical problem to be solved by the present invention is to overcome the defect that the residual current reclosing circuit breaker in the prior art cannot detect the real-time residual current value, so as to provide a residual current calculation method, a calculation device, a storage medium and a detection device.
In order to achieve the purpose, the invention provides the following technical scheme:
in a first aspect, an embodiment of the present invention provides a method for calculating a residual current, including: obtaining the residual current at the current moment after filtering; delaying the filtered current residual current at the current moment for 1/4 period to obtain an orthogonal coordinate signal of the current residual current at the current moment; calculating to obtain an effective value of the residual current according to the current residual current and the orthogonal coordinate signal of the current residual current; and calculating to obtain a real-time value of the residual current according to the effective value of the residual current.
In one embodiment, the effective value of the residual current is calculated by the following formula:
wherein, delta I rms The residual current is an effective value of the residual current, the delta I is the filtered residual current at the current moment, and the delta I' is an orthogonal coordinate signal of the residual current at the current moment.
In an embodiment, the obtaining the filtered current-time residual current includes: acquiring a primary analog signal of residual current at the current moment; performing analog-to-digital conversion on the native analog signal of the residual current at the current moment, and converting the native analog signal of the residual current at the current moment into a digital quantity signal of the residual current at the current moment; and filtering the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm to convert the digital quantity signal into the filtered residual current at the current moment.
In an embodiment, the filtering, processing and converting the digital quantity signal of the current-time residual current into a filtered current-time residual current through a digital low-pass filtering algorithm includes: filtering the digital quantity signal of the residual current at the current moment by a digital low-pass filtering algorithm; and obtaining the amplitude and the initial phase of the residual current from the filtered digital quantity signal of the residual current at the current moment, and obtaining the filtered residual current at the current moment according to the amplitude and the initial phase.
In a second aspect, an embodiment of the present invention provides a device for calculating a residual current, including: the obtaining module is used for obtaining the filtered residual current at the current moment; the extension module is used for delaying the filtered current residual current at the current moment by 1/4 period to obtain an orthogonal coordinate signal of the current residual current at the current moment; the first calculation module is used for calculating an effective value of the residual current according to the current residual current and the orthogonal coordinate signal of the current residual current; and the second calculation module is used for calculating a real-time value of the residual current according to the effective value of the residual current.
In one embodiment, the effective value of the residual current is calculated by the following formula:
wherein, delta I rms The residual current is an effective value of the residual current, the delta I is the filtered residual current at the current moment, and the delta I' is an orthogonal coordinate signal of the residual current at the current moment.
In one embodiment, the obtaining module includes: the acquisition submodule is used for acquiring a native analog signal of residual current at the current moment; the conversion submodule is used for carrying out analog-to-digital conversion on the native analog signal of the residual current at the current moment and converting the native analog signal of the residual current at the current moment into a digital quantity signal of the residual current at the current moment; and the filtering submodule is used for filtering the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm and converting the digital quantity signal into the filtered residual current at the current moment.
In one embodiment, the filtering sub-module includes: the first processing unit is used for filtering the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm; and the second processing unit is used for acquiring the amplitude and the initial phase of the residual current from the filtered digital quantity signal of the residual current at the current moment, and obtaining the filtered residual current at the current moment according to the amplitude and the initial phase.
In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, where computer instructions are stored, and the computer instructions are configured to cause a computer to execute the method for calculating a residual current according to the first aspect of the embodiment of the present invention.
In a fourth aspect, an embodiment of the present invention provides a device for detecting a residual current, including: the circuit comprises a residual current transformer, a current/voltage conversion circuit, a low-pass filter, a differential amplification circuit, a voltage follower circuit and a central operation unit, wherein the residual current transformer is used for acquiring a current residual current signal of a circuit to be tested where the circuit breaker is located; the current/voltage conversion circuit is used for converting the residual current signal into a voltage signal; the low-pass filter is used for performing low-pass filtering on the voltage signal; the differential amplification circuit is used for carrying out differential amplification operation on the voltage signal subjected to the low-pass filtering according to a preset differential amplification operation coefficient; the voltage follower circuit is used for carrying out voltage bias on the voltage signal subjected to the differential amplification operation according to a preset boosting parameter to obtain a primary analog signal of the residual current at the current moment, and inputting the primary analog signal of the residual current at the current moment to the central operation unit; the central arithmetic unit includes: the device comprises a memory and a processor, wherein the memory and the processor are connected in communication with each other, the memory stores computer instructions, and the processor executes the computer instructions to execute the method for calculating the residual current according to the first aspect of the embodiment of the invention.
The technical scheme of the invention has the following advantages:
according to the method for calculating the residual current, the filtered current at the current moment is obtained; delaying the filtered residual current at the current moment for 1/4 period to obtain an orthogonal coordinate signal of the residual current at the current moment; calculating to obtain an effective value of the residual current according to the residual current at the current moment and the orthogonal coordinate signal of the residual current at the current moment; and calculating a real-time value of the residual current according to the effective value of the residual current. The effective value of the residual current is obtained through calculation of the current residual current and the orthogonal coordinate signal of the current residual current, then the real-time value of the residual current is obtained through calculation, real-time monitoring data are provided for the action state of residual current protection and an action value cloud platform, the digital requirement of the residual current reclosing circuit breaker is met, and the problem that the real-time residual current value of the residual current reclosing circuit breaker cannot be detected at present is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a flowchart of a specific example of a method of calculating a residual current in the embodiment of the present invention;
fig. 2 is a flowchart of another specific example of the calculation method of the residual current in the embodiment of the present invention;
fig. 3 is a schematic diagram of a residual current reclosing circuit breaker in an embodiment of the invention;
fig. 4 is a flowchart of another specific example of the method of calculating the residual current in the embodiment of the present invention;
fig. 5 is a schematic diagram of a filtered current-time residual current orthogonal transform signal according to an embodiment of the present invention;
fig. 6 is a functional block diagram of a specific example of a computing device for residual current in an embodiment of the present invention;
FIG. 7 is a functional block diagram of a specific example of an acquisition module in an embodiment of the present invention;
FIG. 8 is a functional block diagram of a specific example of a filtering submodule in an embodiment of the present invention;
fig. 9 is a schematic block diagram of a specific example of a device for detecting a residual current in the embodiment of the present invention;
fig. 10 is a block diagram of a specific example of the central arithmetic unit according to the embodiment of the present invention;
fig. 11 is a schematic block diagram of another specific example of the detection device of the residual current in the embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Furthermore, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The embodiment of the invention provides a method for calculating residual current, which is applied to a central arithmetic unit arranged in a residual current reclosing circuit breaker and is used for detecting the residual current value of the residual current in real time and controlling the action of the circuit breaker according to the relation between the residual current value detected in real time and a preset residual current action value. As shown in fig. 1, the method for calculating the residual current includes the following steps:
step S1: and obtaining the filtered residual current at the current moment.
In a specific embodiment, the filtered current residual current at the current moment is obtained through the steps shown in fig. 2:
step S11: and acquiring a native analog signal of the residual current at the current moment.
In the embodiment of the present invention, as shown in fig. 3, the central processing unit U3 obtains the raw analog signal of the residual current at the current time through the circuit shown in fig. 3, wherein the raw analog signal of the residual current at the current time is a voltage signal. Specifically, the current residual current on the power line is obtained through the induction of the residual current transformer LCT, then the current residual current obtains a voltage signal of the current residual current through the current/voltage conversion function of the detection resistor R4, filtering is performed through the hardware low-pass filter C2, and then the current residual current is input into a differential amplification circuit constructed by the resistors R5, R6, R7 and R8 and the operational amplifier U1A as a detection signal, signal conditioning is performed to reduce common-mode interference signals, and therefore detection precision is improved. The signal output by the operational amplifier U1A is limited by a current limiting resistor Rs to limit the current of the branch in which the current is located, so that the series-connected components are prevented from being burnt out due to overlarge current. In the embodiment of the present invention, the resistance of the current limiting resistor Rs is 100 ohms, which is taken as an example only and not as a limitation. Because the residual current is the commercial power and has a positive and negative part, and the sampling range of the central operation unit U3 is 0-VCC, the voltage signal of the residual current at the current moment needs to be lifted upwards, and the negative part is changed into a positive number so as to meet the sampling requirement of the central operation unit U3. In the embodiment of the invention, the voltage signals after current limiting are all lifted to a positive range through the voltage follower constructed by the resistors R9, R10 and R11 and the operational amplifier U1B, so that the direct-current positive bias operation of the voltage signals is realized, and the sampling requirement of the central operation unit U3 is met. And finally, the voltage signal of the residual current at the current moment after the direct current positive bias calculation is transmitted to a CH1 end of a central operation unit U3, so that the acquisition work of the primary analog signal of the residual current at the current moment is completed. In the embodiment of the present invention, the central processing unit U3 is a single chip, which is taken as an example only and not limited thereto.
Step S12: and performing analog-to-digital conversion on the native analog signal of the residual current at the current moment, and converting the native analog signal of the residual current at the current moment into a digital quantity signal of the residual current at the current moment.
In the embodiment of the present invention, the native analog signal of the current-time residual current transmitted to the CH1 end of the central processing unit U3 needs to be analog-to-digital converted into a digital signal before performing the subsequent signal processing operation. An analog-to-digital conversion circuit is integrated in the central operation unit U3 to realize analog-to-digital conversion. Since the native analog signal of the current-time residual current transmitted to the CH1 of the central operation unit U3 is a voltage signal, what is obtained after the analog-to-digital conversion is a digital quantity signal corresponding to the voltage signal, and then the digital quantity signal corresponding to the voltage signal needs to be converted into a digital quantity signal of the current according to the existing voltage/current conversion formula, that is, into a digital quantity signal of the current-time residual current.
Step S13: and filtering the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm to convert the digital quantity signal into the filtered residual current at the current moment.
In the embodiment of the present invention, through the steps shown in fig. 4, the filtered current residual current at the current moment is obtained:
step S131: and filtering the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm.
Specifically, in the process of acquiring the native analog signal of the current-time residual current, that is, in step S11, the current-time residual current is already filtered by the hardware low-pass filter C2, but since the hardware low-pass filter C2 has a bandwidth limitation, the digital low-pass filtering needs to be performed again in the central operation unit U3. Specifically, the digital low-pass filtering algorithm is as follows:
Y(n)＝ki*X(n)+(1-ki)Y(n-1)
y (n) is the value of the nth digitized low-pass filtering output, Y (n-1) is the value of the nth digitized low-pass filtering output, X (n) is the digital quantity signal of the residual current at the current moment, and ki is the time constant of the digitized low-pass filtering. In the embodiment of the invention, the cut-off frequency of the time constant of the digital low-pass filtering is set to be 3-5 times of the frequency of the original analog signal of the residual current at the current moment converted into the digital quantity signal of the residual current at the current moment by using engineering experience.
Step S132: and obtaining the amplitude and the initial phase of the residual current from the filtered digital quantity signal of the residual current at the current moment, and obtaining the filtered residual current at the current moment according to the amplitude and the initial phase.
Specifically, the amplitude and the initial phase of the residual current are obtained from the digital quantity signal of the filtered residual current at the current moment, and an expression Δ I = Asin (ω t + θ) of the filtered residual current is established according to the amplitude and the initial phase, where Δ I is the filtered residual current at the current moment, a is the amplitude, ω is the angular frequency, and θ is the initial phase, and the filtered residual current at the current moment is obtained according to the expression of the filtered residual current.
Step S2: delaying the filtered residual current at the current moment for 1/4 period to obtain an orthogonal coordinate signal of the residual current at the current moment.
In one embodiment, as shown in fig. 5, 1 is the filtered current residual current at the current time, and 2 is the orthogonal coordinate signal of the current residual current at the current time. Delaying the filtered current residual current at the current moment by 1/4 period to obtain an orthogonal coordinate signal of the current residual current, namely delaying Δ I = Asin (ω T + θ) by 1/4 period to obtain Δ I '= Asin (ω (T-T/4) + θ), wherein Δ I' is the orthogonal coordinate signal of the current residual current. In the embodiment of the present invention, the angular frequency ω is set to
Δ I' = Acos (ω t + θ) is available,
and step S3: and calculating to obtain the effective value of the residual current according to the residual current at the current moment and the orthogonal coordinate signal of the residual current at the current moment.
In one embodiment, a modulus operation is performed according to the current-time residual current and the orthogonal coordinate signal of the current-time residual current, and an effective value of the residual current is obtained through calculation. In the embodiment of the present invention, the effective value of the residual current is calculated by the following formula:
wherein, delta I rms And the delta I is an effective value of the residual current, the delta I is the filtered residual current at the current moment, and the delta I' is an orthogonal coordinate signal of the residual current at the current moment.
Specifically, the angular frequency ω is set to
At this time, Δ I = Asin (ω t + θ), Δ I' = Acos (ω t + θ), and Δ I = Asin (ω t + θ) is calculated rms And (d) = a. The effective value of the residual current at this time is a, which is the amplitude of the filtered residual current at the current time in the expression Δ I = Asin (ω t + θ).
And step S4: and calculating a real-time value of the residual current according to the effective value of the residual current.
In one embodiment, the amplitude of the residual current is obtained according to the relation between the amplitude and the effective value
Will receive an amplitude of the residual current->
Expression substituted into a residual current pickup>
Where I is the real-time value of the residual current. And then, owing to the amplitude of the residual current>
The angular frequency ω and the initial phase θ are both known quantities, so that a real-time value of the residual current can be obtained.
In practical applications, the steps S1 to S4 can be implemented by the central operation unit U3 shown in fig. 3, and specifically, hardware circuits and corresponding algorithm programs for implementing the steps can be integrated in the central operation unit U3, so that the real-time value of the residual current is directly output to the external device terminal through the central operation unit U3.
According to the method for calculating the residual current, the filtered current at the current moment is obtained; delaying the filtered residual current at the current moment for 1/4 period to obtain an orthogonal coordinate signal of the residual current at the current moment; calculating to obtain an effective value of the residual current according to the residual current at the current moment and the orthogonal coordinate signal of the residual current at the current moment; and calculating a real-time value of the residual current according to the effective value of the residual current. The effective value of the residual current is obtained through calculation of the current residual current and the orthogonal coordinate signal of the current residual current, then the real-time value of the residual current is obtained through calculation, real-time monitoring data are provided for the action state of residual current protection and an action value cloud platform, the digital requirement of the residual current reclosing circuit breaker is met, and the problem that the real-time residual current value of the residual current reclosing circuit breaker cannot be detected at present is solved.
In one embodiment, the action of the residual current reclosing circuit breaker is controlled according to the relation between the real-time value of the residual current and the preset residual current action value.
In the embodiment of the present invention, according to the schematic diagram of the residual current reclosing circuit breaker shown in fig. 3, it can be known that the specific operating principle is as follows: a double-power-supply loop consisting of a switching power supply and a linear power supply supplies power for the residual current reclosing circuit breaker. And controlling the action of the residual current reclosing circuit breaker by judging whether the real-time value of the residual current exceeds a preset residual current action value or not. When the residual current exceeds the preset residual current working value, the action of a release of the residual current reclosing circuit breaker is controlled (such as the function of an F2 protection release in figure 3), so that the residual current reclosing circuit breaker is disconnected. The central operation unit U3 is in communication connection with an external terminal device through a 485 serial port, and drives the residual current reclosing circuit breaker to open or reclose according to a control signal sent by the terminal device (for example, the F1 reclosing driving function in fig. 3). The operating mode of the residual current circuit breaker can be a manual operating mode or an automatic operating mode (e.g. F5 manual/automatic in fig. 3), when the operating mode is the manual operating mode, the user manually controls the circuit breaker to be reclosed, and when the operating mode is the automatic operating mode, the user controls the central operation unit U3 to drive the circuit breaker to be reclosed through an external terminal device. By providing a clock circuit (e.g., the F4RTC clock circuit in fig. 3) connected to the central processing unit U3, when a leakage phenomenon occurs, it is convenient for a user to know when the leakage occurs.
An embodiment of the present invention further provides a device for calculating a residual current, as shown in fig. 6, including:
and the obtaining module 10 is configured to obtain the filtered current residual current at the current moment. For details, refer to the related description of step S1 in the above method embodiment, and are not repeated herein.
And the prolonging module 20 is used for delaying the filtered residual current at the current moment by 1/4 period to obtain an orthogonal coordinate signal of the residual current at the current moment. For details, refer to the related description of step S2 in the above method embodiment, and are not described herein again.
The first calculating module 30 is configured to calculate an effective value of the residual current according to the current residual current and the orthogonal coordinate signal of the current residual current. For details, refer to the related description of step S3 in the above method embodiment, and are not repeated herein.
And the second calculating module 40 is configured to calculate a real-time value of the residual current according to the valid value of the residual current. For details, refer to the related description of step S4 in the above method embodiment, and are not described herein again.
The device for calculating the residual current provided by the invention applies the method for calculating the residual current, and the method for calculating the residual current provided by the invention obtains the filtered residual current at the current moment; delaying the filtered residual current at the current moment for 1/4 period to obtain an orthogonal coordinate signal of the residual current at the current moment; calculating to obtain an effective value of the residual current according to the residual current at the current moment and the orthogonal coordinate signal of the residual current at the current moment; and calculating a real-time value of the residual current according to the effective value of the residual current. The effective value of the residual current is obtained through calculation of the current residual current and the orthogonal coordinate signal of the current residual current, and then the real-time value of the residual current is obtained through calculation, real-time monitoring data are provided for the action state and the action value cloud platform of residual current protection, the digital requirement of the residual current reclosing circuit breaker is met, and the problem that the real-time residual current value of the residual current reclosing circuit breaker cannot be detected at present is solved.
In one embodiment, the effective value of the residual current is calculated by the following formula:
wherein, delta I rms The residual current is an effective value of the residual current, the delta I is the filtered residual current at the current moment, and the delta I' is an orthogonal coordinate signal of the residual current at the current moment. For details, refer to the related description of step S3 in the above method embodiment, and are not described herein again.
In one embodiment, the obtaining module 10, as shown in fig. 7, includes:
the acquisition submodule 101 is configured to acquire a native analog signal of a residual current at a current time. For details, refer to the related description of step S11 in the above method embodiment, and are not described herein again.
The conversion submodule 102 is configured to perform analog-to-digital conversion on the native analog signal of the residual current at the current time, and convert the native analog signal of the residual current at the current time into a digital quantity signal of the residual current at the current time. For details, refer to the related description of step S12 in the above method embodiment, and are not repeated herein.
And the filtering submodule 103 is configured to perform filtering processing on the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm to convert the digital quantity signal into a filtered residual current at the current moment. For details, refer to the related description of step S13 in the above method embodiment, and are not repeated herein.
In one embodiment, the filtering sub-module 103, as shown in fig. 8, includes:
and a first processing unit 1031, configured to perform filtering processing on the digital quantity signal of the residual current at the current time through a digital low-pass filtering algorithm. For details, refer to the related description of step S131 in the above method embodiment, and are not repeated herein.
The second processing unit 1032 is configured to obtain the amplitude and the initial phase of the residual current from the filtered digital quantity signal of the residual current at the current time, and obtain the filtered residual current at the current time according to the amplitude and the initial phase. For details, refer to the related description of step S132 in the above method embodiment, and are not repeated herein.
An embodiment of the present invention provides a device for detecting a residual current, as shown in fig. 9, including: the circuit breaker testing device comprises a residual current transformer 50, a current/voltage conversion circuit 60, a low-pass filter 70, a differential amplification circuit 80, a voltage following circuit 90 and a central operation unit 100, wherein the residual current transformer 50 is used for acquiring a current-time residual current signal of a circuit to be tested where the circuit breaker is located; a current/voltage conversion circuit 60 for converting the residual current signal into a voltage signal; a low-pass filter 70 for low-pass filtering the voltage signal; a differential amplification circuit 80, configured to perform differential amplification operation on the low-pass filtered voltage signal according to a preset differential amplification operation coefficient; the voltage follower circuit 90 is configured to boost the voltage signal after the differential amplification operation according to a preset boost parameter to obtain a native analog signal of the residual current at the current time, and input the native analog signal of the residual current at the current time to the central operation unit 100.
In the embodiment of the invention, the preset differential amplification operation coefficient and the preset boosting parameter can be determined according to an internal circuit of the residual current detection equipment. According to the circuit shown in fig. 3, the obtained preset differential amplification operation coefficient is determined by the resistors R5, R6, R7 and R8, and the preset boosting parameter is determined by the resistors R9 and R10.
As shown in fig. 10, the central processing unit 100 includes: a processor 101 and a memory 102, wherein the processor 101 and the memory 102 may be connected by a bus or other means, and fig. 10 illustrates the connection by the bus as an example.
The processor 101 may be a Central Processing Unit (CPU). The Processor 101 may also be other general purpose processors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or combinations thereof.
The memory 102, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as the corresponding program instructions/modules in embodiments of the present invention. The processor 101 executes various functional applications and data processing of the processor, i.e. implementing the calculation method of the residual current in the above method embodiments, by running non-transitory software programs, instructions and modules stored in the memory 102.
The memory 102 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor 101, and the like. Further, the memory 102 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, memory 102 may optionally include memory located remotely from processor 101, which may be connected to processor 101 via a network. Examples of such networks include, but are not limited to, the internet, intranets, mobile communication networks, and combinations thereof.
One or more modules are stored in the memory 102 and, when executed by the processor 101, perform the method of calculating the residual current as in the embodiment shown in fig. 1-5.
The details of the computer device can be understood by referring to the corresponding descriptions and effects in the embodiments shown in fig. 1-5, and are not described herein again.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program that can be stored in a computer-readable storage medium and that when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD), a Solid State Drive (SSD), or the like; the storage medium may also comprise a combination of memories of the kind described above.
In an embodiment, the device for detecting a residual current, as shown in fig. 11, further includes: the reclosing circuit comprises a reclosing drive circuit 110, a release protection circuit 120, a 485 serial port communication circuit 130, an RTC clock circuit 140 and a manual/automatic switching circuit 150, wherein the reclosing drive circuit 110 is used for driving a residual current reclosing circuit breaker to open or reclose according to a control signal sent by an external terminal device; the tripper protection circuit 120 is used for controlling the tripper action of the residual current reclosing circuit breaker to disconnect the residual current reclosing circuit breaker when the real-time value of the residual current exceeds the preset residual current working value; the 485 serial port communication circuit 130 is used for communication connection of external terminal equipment; the RTC clock circuit 140 is used for synchronizing time, and when a leakage phenomenon occurs, a user can know when the leakage occurs conveniently; the manual/automatic switching circuit 150 is used for switching the operating mode of the residual current circuit breaker, and may be a manual or automatic operating mode.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (8)
1. A method for calculating a residual current, comprising:
obtaining the residual current at the current moment after filtering;
delaying the filtered residual current at the current moment for 1/4 period to obtain an orthogonal coordinate signal of the residual current at the current moment;
calculating to obtain an effective value of the residual current according to the current residual current and the orthogonal coordinate signal of the current residual current;
calculating to obtain a real-time value of the residual current according to the effective value of the residual current;
the effective value of the residual current is calculated by the following formula:
wherein, delta I rms Is the effective value of the residual current, and is the residual current at the current moment after filtering ′ Is an orthogonal coordinate signal of the residual current at the current moment.
2. The method for calculating the residual current according to claim 1, wherein the obtaining the filtered current-time residual current comprises:
acquiring a primary analog signal of residual current at the current moment;
performing analog-to-digital conversion on the native analog signal of the residual current at the current moment, and converting the native analog signal of the residual current at the current moment into a digital quantity signal of the residual current at the current moment;
and filtering the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm to convert the digital quantity signal into the filtered residual current at the current moment.
3. The method for calculating the residual current according to claim 2, wherein the step of performing filtering processing on the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm to convert the digital quantity signal of the residual current at the current moment into the filtered residual current at the current moment comprises:
filtering the digital quantity signal of the residual current at the current moment by a digital low-pass filtering algorithm;
and obtaining the amplitude and the initial phase of the residual current from the filtered digital quantity signal of the residual current at the current moment, and obtaining the filtered residual current at the current moment according to the amplitude and the initial phase.
4. A device for calculating a residual current, comprising:
the obtaining module is used for obtaining the filtered residual current at the current moment;
the extension module is used for delaying the filtered residual current at the current moment by 1/4 period to obtain an orthogonal coordinate signal of the residual current at the current moment;
the first calculation module is used for calculating an effective value of the residual current according to the current residual current and the orthogonal coordinate signal of the current residual current;
the second calculation module is used for calculating a real-time value of the residual current according to the effective value of the residual current;
the effective value of the residual current is calculated by the following formula:
wherein, delta I rms Is the effective value of the residual current, and is the residual current at the current moment after filtering ′ Is an orthogonal coordinate signal of the residual current at the current moment.
5. The device for calculating the residual current according to claim 4, characterized in that the acquisition module comprises:
the acquisition submodule is used for acquiring a native analog signal of residual current at the current moment;
the conversion submodule is used for carrying out analog-to-digital conversion on the native analog signal of the residual current at the current moment and converting the native analog signal of the residual current at the current moment into a digital quantity signal of the residual current at the current moment;
and the filtering submodule is used for filtering and converting the digital quantity signal of the residual current at the current moment into the filtered residual current at the current moment through a digital low-pass filtering algorithm.
6. The device for calculating the residual current according to claim 5, characterized in that said filtering submodule comprises:
the first processing unit is used for filtering the digital quantity signal of the residual current at the current moment through a digital low-pass filtering algorithm;
and the second processing unit is used for acquiring the amplitude and the initial phase of the residual current from the filtered digital quantity signal of the residual current at the current moment, and obtaining the filtered residual current at the current moment according to the amplitude and the initial phase.
7. A computer-readable storage medium storing computer instructions for causing a computer to execute the method of calculating a residual current according to any one of claims 1 to 3.
8. A device for detecting a residual current, comprising: a residual current transformer, a current/voltage conversion circuit, a low-pass filter, a differential amplification circuit, a voltage follower circuit and a central arithmetic unit, wherein,
the residual current transformer is used for acquiring a current-time residual current signal of a circuit to be tested where the circuit breaker is located;
the current/voltage conversion circuit is used for converting the residual current signal into a voltage signal;
the low-pass filter is used for performing low-pass filtering on the voltage signal;
the differential amplification circuit is used for carrying out differential amplification operation on the voltage signal subjected to the low-pass filtering according to a preset differential amplification operation coefficient;
the voltage follower circuit is used for carrying out voltage bias on the voltage signal subjected to the differential amplification operation according to a preset boosting parameter to obtain a primary analog signal of the residual current at the current moment, and inputting the primary analog signal of the residual current at the current moment to the central operation unit;
the central arithmetic unit includes: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the method of calculating a residual current according to any one of claims 1 to 3.
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