Control method and apparatus for type-b residual current protective device

Abstract

Disclosed in the present invention are a control method and apparatus for a type-B residual current protective device. The control method comprises the following steps: carrying out demodulation and sampling on the waveform of the residual current of a type-B residual current protective device, acquiring a plurality of sampling points of the waveform within a sampling period, carrying out fast Fourier transformation processing on the plurality of sampling points to obtain a plurality of frequency domain components, and forming feature vectors by the plurality of frequency domain components; acquiring a decision tree model, inputting the feature vectors Y into the decision tree model to obtain a target waveform outputted by the decision tree model, and acquiring a protection threshold corresponding to the target waveform; and calculating an effective value X, and when X is greater than the protection threshold, disconnecting the type-B residual current protective device. Therefore, different waveforms can be processed.

Description

Control method for B-type residual current protector and device thereof

[0001] The present application is based on and claims priority to Chinese Patent Application No. 202410474417.5, filed on April 19, 2024, the entire contents of which are hereby incorporated by reference into the present application. TECHNICAL FIELD

[0002] The present application relates to the technical field of residual current protection, and in particular to a control method for a B-type residual current protector and a device thereof. BACKGROUND

[0003] A residual current device (RCD) is an electrical appliance widely used in power distribution systems to protect personal safety and prevent electrical fires and damage to electrical equipment. With the development of electric vehicles and the demand for energy-saving, high-frequency, and precise control of industrial electrical equipment, devices such as motor inverters are being used extensively. These devices generate residual currents, including pure DC residual currents, three-phase rectified residual currents, and high-frequency residual currents. Therefore, the application of B-type residual current circuit breakers is essential and necessary. The national standard GB 22794-2008 "B-type residual current circuit breakers without and with overcurrent protection for household and similar use" clearly specifies the requirements and tests for B-type residual current circuit breakers.

[0004] Therefore, how to enable the B-type residual current protector to process different waveforms has become a problem to be solved.

[0005] Any prior art mentioned in the specification does not mean that it is recognized or suggested that the prior art constitutes part of the common general knowledge in any jurisdiction, or that the prior art can be reasonably expected to be understood, considered relevant, and / or combined with other prior art by those skilled in the art. SUMMARY

[0006] The present application aims to provide a control method for a B-type residual current protector and a device thereof.

[0007] To achieve one of the above-mentioned purposes, an embodiment of the present application provides a control method for a B-type residual current protector, comprising the following steps: demodulating and sampling the waveform of the residual current of the B-type residual current protector, and obtaining 2*Num sampling points of the waveform in one sampling period , performing fast Fourier transform processing on the 2*Num sampling points , and obtaining a plurality of frequency domain components , and selecting a plurality of frequency domain components the feature vector Y is composed of the frequency domain components , wherein Num is a natural number; obtaining a decision tree model, the decision tree model being trained by a plurality of B-type residual currents and a feature vector corresponding to each B-type residual current; inputting the feature vector Y into the decision tree model and obtaining a target waveform output by the decision tree model; obtaining a protection threshold corresponding to the target waveform; calculating the effective value , and when X> the protection threshold, disconnecting the B-type residual current protector.

[0008] As a further improvement of the embodiment of the application, the B-type residual current protector further comprises a coil driving module, an electromagnetic mutual inductor MI and a coil L, the coil L being wound on the electromagnetic mutual inductor, a first end of the coil L being electrically connected to the coil driving module, the coil driving module being used for receiving a PWM signal so as to drive the coil L to complete magnetic modulation of the residual current; the "demodulating and sampling the waveform of the residual current of the B-type residual current protector" specifically comprises: collecting a voltage value of the residual current from a second end of the coil L at a rising edge of the PWM signal, so as to obtain the waveform of the residual current and demodulate and sample the waveform.

[0009] As a further improvement of the embodiment of the application, the plurality of B-type residual currents at least comprise: an AC current, an A0° current, an A90° current, an A135° current, a 2PDC current, a 3PDC current, an SDC current, an F current, an AC150Hz current, an AC400Hz current and an AC1000Hz current.

[0010] As a further improvement of the embodiment of the application, the B-type residual current protector is provided with a thyristor and a tripping device; the "disconnecting the B-type residual current protector" specifically comprises: making the thyristor conduct, so as to make the tripping device electrified, and the tripping device disconnecting the B-type residual current protector.

[0011] As a further improvement of the embodiment of the application, Num=32.

[0012] The embodiment of the application further provides a control device for a B-type residual current protector, comprising the following modules: a preprocessing module, used for demodulating and sampling a waveform of a residual current of the B-type residual current protector, and obtaining 2*Num sampling points of the waveform in a sampling period , performing fast Fourier transform on the 2*Num sampling points , and obtaining a plurality of frequency domain components , and composing a feature vector Y from the frequency domain components , wherein Num is a natural number; a decision tree processing module, configured to acquire a decision tree model, wherein the decision tree model is trained by a plurality of B-type residual currents and a feature vector corresponding to each B-type residual current; input the feature vector Y into the decision tree model, and obtain a target waveform output by the decision tree model; acquire a protection threshold corresponding to the target waveform; a judging module, configured to calculate an effective value , and when X> the protection threshold, disconnect the B-type residual current protector.

[0013] As a further improvement of the embodiment of the present application, the B-type residual current protector further comprises a coil driving module, an electromagnetic mutual inductor MI and a coil L, wherein the coil L is wound on the electromagnetic mutual inductor MI, a first end of the coil L is electrically connected to the coil driving module, and the coil driving module is configured to receive a PWM signal to drive the coil L to complete magnetic modulation of the residual current; the preprocessing module is further configured to collect a voltage value of the residual current from a second end of the coil L at a rising edge of the PWM signal, thereby obtaining a waveform of the residual current, and demodulating and sampling the waveform.

[0014] As a further improvement of the embodiment of the present application, the plurality of B-type residual currents at least include: an AC current, an A0° current, an A90° current, an A135° current, a 2PDC current, a 3PDC current, an SDC current, an F current, an AC150Hz current, an AC400Hz current and an AC1000Hz current.

[0015] As a further improvement of the embodiment of the present application, the B-type residual current protector is provided with a thyristor and a tripping device.

[0016] The judging module is further configured to make the thyristor conduct, thereby making the tripping device energized, and the tripping device disconnects the B-type residual current protector.

[0017] As a further improvement of the embodiment of the present application, Num=32.

[0018] Compared with the prior art, the application has the beneficial effects that the embodiment of the application discloses a control method for a B-type residual current protector and a device thereof, the control method comprises the following steps: demodulating and sampling a waveform of a residual current of the B-type residual current protector, obtaining a plurality of sampling points of the waveform in a sampling period, performing fast Fourier transform processing on the plurality of sampling points, and obtaining a plurality of frequency domain components, and forming a feature vector by using the plurality of frequency domain components; obtaining a decision tree model, the decision tree model is trained by using a plurality of B-type residual currents and a feature vector corresponding to each B-type residual current; inputting the feature vector Y into the decision tree model, obtaining a target waveform output by the decision tree model, obtaining a protection threshold corresponding to the target waveform; calculating an effective value X, when X> the protection threshold, disconnecting the B-type residual current protector. Therefore, different waveforms can be processed.

[0019] The terms "comprise" and variations of the term, such as "comprises" and "comprised of", "comprising", "including", "containing" as used herein, are not intended to exclude other features, ingredients, components, or steps. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 is a schematic diagram of a B-type residual current protector according to an embodiment of the application;

[0021] Fig. 2 is a flowchart of a control method for a B-type residual current protector according to an embodiment of the application;

[0022] Fig. 3 is a schematic diagram of a decision tree according to an embodiment of the application. DETAILED DESCRIPTION

[0023] The application will be described in detail below with reference to the embodiments shown in the drawings. However, the embodiments do not limit the application, and any changes in structure, method, or function made by those skilled in the art based on the embodiments are included in the protection scope of the application.

[0024] The following description and drawings are illustrative of the specific embodiments herein and are not intended to be limiting. Parts and features of some embodiments can be included or replaced by parts and features of other embodiments. The scope of the embodiments herein includes the entire scope of the claims and all available equivalents thereof. In this document, the terms "first," "second," etc. are used merely as identifiers that distinguish one element from another, and are not intended to signify or imply that the elements so identified must have a particular relationship to one another or be in a particular order, unless otherwise specified and limited. In fact, the first element could be the second element, and vice versa. Also, the terms "comprise," "comprising," or any other variation thereof are intended to cover a non-exclusive inclusion, such that a structure, device, or apparatus that comprises a list of elements is not necessarily limited to only those elements, but can include other elements not expressly listed or inherent to such structure, device, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the structure, device, or apparatus that includes the element. Various embodiments are described with progression in this document, each embodiment emphasizing related aspects that distinguish it from other embodiments. Each embodiment can provide from 1% to 99% or more of the aspects creating a merit to the inventive proceeding. Accordingly, the embodiments described herein are not mutually exclusive, but are to be appreciated separately or in any combination.

[0025] The terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like in the description and in the claims mean the orientation or positional relationship as shown in the drawings, and are used only to facilitate the description of the application and to simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the application. In the description of the present application, unless otherwise specified and limited, the terms "mounting," "connecting," "connection" should be interpreted broadly, for example, they can be mechanical or electrical connections, or internal communication between two elements, and can be direct connection or indirect connection through an intermediate medium, and the specific meaning of the above terms can be understood by those skilled in the art according to the specific circumstances.

[0026] The principle of the B-type residual current protector is as follows: as shown in FIG. 1, an AC-DC module converts 220V DC of input grid voltage into 6V DC, a DC-DC module converts 6V DC into 5V DC and 2.5V DC, 5V DC is used for an MCU (Microcontroller Unit) and a coil drive, 2.5V DC is used for magnetic modulation DC bias. The coil drive increases the current driving capability of the PWM (Pulse Width Modulation) output of the MCU, thereby driving the inductor L1, completing the magnetic modulation of the residual current, converting the modulated residual current into voltage through the resistor R1, and inputting the MCU for ADC (Analog-to-Digital Converter) sampling processing. The MCU control module mainly completes the magnetic modulation PWM waveform output, the ADC sampling of the residual current, and the calculation. According to the calculation result, when the set threshold is exceeded, the tripping device is controlled to trip, so that the circuit breaker is disconnected. The tripping protection module is mainly composed of a thyristor and a tripping device, receives the output control of the MCU, and when the MCU outputs a high level, the thyristor is turned on, so that the tripping device is powered on to work, and the circuit breaker is disconnected.

[0027] The embodiment one of the present application provides a control method for a B-type residual current protector, as shown in FIG. 2, comprising the following steps:

[0028] Step 201: demodulating and sampling the waveform of the residual current of the B-type residual current protector, and obtaining 2*Num sampling points of the waveform in a sampling period , performing fast Fourier transform processing on the 2*Num sampling points , and obtaining a plurality of frequency domain components , the plurality of frequency domain components are composed into a feature vector , wherein Num is a natural number;

[0029] Fig. 1 shows the schematic diagram of the control method, wherein the AC-DC module is used to convert the direct current input from the receiving power grid into direct current, for example, convert the 220V direct current in the power grid into 6V direct current; the DC-DC module is used to change the voltage of the direct current output by the AC-DC module and deliver to the MCU and the coil driving module, for example: convert the 6V direct current into 5V direct current and 2.5V direct current, deliver the 5V direct current to the MCU and the coil driving for use, and the 2.5V direct current is used for the magnetic modulation direct current bias; the coil driving module is used to receive the control signal (for example, PWM signal, the full name of PWM is pulse width modulation, and the Chinese name is: pulse width modulation) output by the MCU, so as to change the current driving ability, thereby driving the inductor L1, completing the magnetic modulation of the residual current, and then converting the modulated residual current into voltage through the resistor R1, inputting the MCU for ADC (Analog-to-Digital Converter, Analog-to-Digital Converter) sampling processing, and the MCU (Micro Controller Unit, Micro Controller Unit) will execute the control method. The MCU can be a HuaDa M4 core HC32F460 chip with a frequency of 200MHz and DSP computing function, which is suitable for B-type residual current FFT calculation and waveform classification identification.

[0030] In the experiment of the control method, the highest frequency of the B-type residual current used by the inventor is 1KHz, and according to the Shannon sampling theorem, the minimum sampling frequency is 2KHz.

[0031] Step 202: obtaining a decision tree model trained by a plurality of B-type residual currents and a feature vector corresponding to each B-type residual current; inputting the feature vector Y into the decision tree model to obtain a target waveform output by the decision tree model, and obtaining a protection threshold corresponding to the target waveform;

[0032] Here, first, the feature vectors of a plurality of B-type residual currents are obtained to form a feature vector database, and then the decision tree model is trained based on the database. In the experiment of the inventor, a plurality of B-type residual currents (at least including: AC current, A0° current, A90° current, A135° current, 2PDC current, 3PDC current, SDC current, F current, AC150Hz current, AC400Hz current and AC1000Hz current). 10000 groups of data are sampled for each current, and 110000 data form a waveform feature database, and the database file is named as wave.csv.

[0033] After that, read the wave.csv file and label the waveform category. Take 80% of the database data to train the decision tree, and use the decision tree maximum entropy and tree depth 4 as the parameter to perform machine learning training to obtain a complete decision tree, and then test the 20% data of the database. In the inventor's experiment, it is carried out in an offline manner, and is realized by using a python language on a notebook computer.

[0034] AC refers to alternating current residual current, A0° refers to residual current with a current lag angle of 0° (or half-wave residual current), A90° refers to residual current with a current lag angle of 90°, A135° refers to residual current with a current lag angle of 135°, 2PDC refers to pulsating direct current residual current generated by a two-phase power supply rectifier circuit, 3PDC refers to pulsating direct current residual current generated by a three-phase power supply rectifier circuit, SDC refers to smooth direct current residual current, F refers to composite residual current, B refers to B-type | F-type residual current, AC150Hz refers to 150Hz alternating current residual current: the waveform feature is alternating current, the frequency is 150Hz, and the corresponding leakage occurs at the output end of the frequency converter, AC400Hz refers to 400Hz alternating current residual current: the waveform feature is alternating current, the frequency is 400Hz, and the corresponding leakage occurs at the output end of the frequency converter, and AC1000Hz refers to 1000Hz alternating current residual current: the waveform feature is alternating current, the frequency is 1000Hz, and the corresponding leakage occurs at the output end of the frequency converter.

[0035] Here, as shown in FIG. 3, the decision tree is a supervised method, and the working principle is: classifying data instances (in the control method of the embodiment, the data instance is the feature vector Y) by traversing a tree structure from the root node to the leaf node. It can be understood that the decision tree is composed of two elements: nodes and edges connecting the nodes. The decision flow is as follows: starting from the root node, selecting an edge at each node, jumping to the next node, until reaching the leaf node, and making a decision. Each node represents a judgment on a specific feature (conditional attribute), and the branch represents various different feature values of the feature.

[0036] In the decision tree model obtained in the inventor's experiment, 5 variables are selected , and the pseudo code of the decision tree model is as follows:

[0037] if z1>=TH1

[0038] if z2>TH2

[0039] Wave=A0° current

[0040] else

[0041] if z5>=TH3

[0042] Wave = F current

[0043] else

[0044] Wave = AC current

[0045] else

[0046] if z2>=TH4

[0047] if z3>=TH5

[0048] Wave = A90° current

[0049] else

[0050] Wave = 2PDC current

[0051] else

[0052] if z5>=TH6

[0053] Wave = AC1000Hz current

[0054] else

[0055] if z4>=TH7

[0056] Wave = AC400Hz current

[0057] else

[0058] if z3>=TH8

[0059] Wave = AC150Hz current

[0060] else

[0061] if z3>=TH9

[0062] Wave = 3PDC current

[0063] else

[0064] if z3>=TH10

[0065] Wave = A135° current

[0066] else

[0067] if z1>=TH11

[0068] if z1>=TH12

[0069] Wave = A0° current

[0070] else

[0071] Wave = SDC current

[0072] else

[0073] Wave = A0° current

[0074] Among them, TH1=52.5, TH2=11.5, TH3=3, TH4=18.5, TH5=9.5, TH6=8, TH7=28.5, TH8=68, TH9=15.5, TH10=11.5, TH11=26.5, and TH12=33.5.

[0075] Step 203: Calculate effective value , when X>the protection threshold, disconnect the type B residual current protector.

[0076] In this embodiment, the type B residual current protector further includes: a coil driving module, an electromagnetic transformer MI, and a coil L, wherein the coil L is wound around the electromagnetic transformer, and a first end of the coil L is electrically connected to the coil driving module, and the coil driving module is used to receive a PWM signal, thereby driving the coil L to complete magnetic modulation of the residual current;

[0077] The "demodulating and sampling the waveform of the residual current of the type B residual current protector" specifically includes: collecting the voltage value of the residual current from the second end of the coil L at the rising edge of the PWM signal, thereby obtaining the waveform of the residual current, and demodulating and sampling the waveform.

[0078] Here, the PWM signal may be output by an MCU. Optionally, the frequency of the PWM signal is 3.2 kHz, and the demodulation sampling frequency is also 3.2 kHz, thereby obtaining the residual current sampling values ​​X1, X2, ..., X64 with a 50 Hz cycle of 20 ms.

[0079] In this embodiment, the multiple B-type residual currents include at least:

[0080] AC current, A0° current, A90° current, A135° current, 2PDC current, 3PDC current, SDC current, F current, AC150Hz current, AC400Hz current, and AC1000Hz current.

[0081] In this embodiment, the B-type residual current protector is provided with a thyristor and a trip unit;

[0082] The "disconnecting the B-type residual current protector" specifically includes: making the thyristor conduct, thereby making the tripping device energized, and the tripping device disconnects the B-type residual current protector.

[0083] In the embodiment, Num=32.

[0084] The embodiment two of the present application provides a control device for a B-type residual current protector, comprising the following modules:

[0085] A preprocessing module is configured to demodulate and sample a waveform of residual current of the B-type residual current protector, and obtain 2*Num sampling points of the waveform in a sampling period , perform fast Fourier transform on the 2*Num sampling points , and obtain a plurality of frequency domain components , and compose a feature vector from the plurality of frequency domain components , wherein Num is a natural number.

[0086] A decision tree processing module is configured to obtain a decision tree model, wherein the decision tree model is trained by a plurality of B-type residual currents and a feature vector corresponding to each B-type residual current, input the feature vector Y into the decision tree model, obtain a target waveform output by the decision tree model, and obtain a protection threshold corresponding to the target waveform.

[0087] A judging module is configured to calculate an effective value , and disconnect the B-type residual current protector when X is greater than the protection threshold.

[0088] In the embodiment, the B-type residual current protector further comprises a coil driving module, an electromagnetic mutual inductor MI and a coil L, the coil L is wound on the electromagnetic mutual inductor, a first end of the coil L is electrically connected to the coil driving module, and the coil driving module is configured to receive a PWM signal, thereby driving the coil L to complete magnetic modulation of residual current.

[0089] The preprocessing module is further configured to collect a voltage value of residual current from a second end of the coil L at a rising edge of the PWM signal, thereby obtaining a waveform of the residual current, and demodulating and sampling the waveform.

[0090] In the embodiment, the plurality of B-type residual currents at least include:

[0091] AC current, A0° current, A90° current, A135° current, 2PDC current, 3PDC current, SDC current, F current, AC150Hz current, AC400Hz current and AC1000Hz current.

[0092] In the embodiment, the B-type residual current protector is provided with a thyristor and a tripping device.

[0093] The judging module is further configured to make the thyristor conduct, so that the tripping device is energized, and the tripping device disconnects the B-type residual current protector.

[0094] In the embodiment, Num=32.

[0095] It should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the specification is described in this way only for clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

[0096] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present application, and are not intended to limit the protection scope of the present application, and equivalent embodiments or changes made without departing from the spirit of the present application should be included in the protection scope of the present application.

Claims

1. A control method for a type B residual current protector, characterized in that, comprising the following steps: Demodulate and sample the waveform of the residual current of the type B residual current protector, and obtain 2*Num sampling points of the waveform in a sampling period For 2*Num samples performing a fast Fourier transform process and obtaining a number of frequency domain components a number of frequency domain components composition feature vector wherein Num is a natural number; obtaining a decision tree model, the decision tree model being trained by a plurality of B-type residual currents and a feature vector corresponding to each B-type residual current; inputting the feature vector Y into the decision tree model, and obtaining a target waveform output by the decision tree model, and obtaining a protection threshold corresponding to the target waveform; Computing effective values when X>the protection threshold, disconnecting the B-type residual current protector.

2. The control method according to claim 1, wherein: the B-type residual current protector further comprises a coil driving module, an electromagnetic transformer MI, and a coil L, the coil L being wound on the electromagnetic transformer MI, a first end of the coil L being electrically connected to the coil driving module, and the coil driving module being configured to receive a PWM signal to drive the coil L to complete magnetic modulation of the residual current; the "demodulating and sampling the waveform of the residual current of the B-type residual current protector" specifically comprises: collecting a voltage value of the residual current from a second end of the coil L at a rising edge of the PWM signal, thereby obtaining the waveform of the residual current, and demodulating and sampling the waveform.

3. The control method according to claim 1, characterized by, The plurality of B-type residual currents at least comprises: AC current, A0° current, A90° current, A135° current, 2PDC current, 3PDC current, SDC current, F current, AC150Hz current, AC400Hz current, and AC1000Hz current.

4. The control method according to claim 1, wherein: the B-type residual current protector is provided with a thyristor and a tripping device; the "disconnecting the B-type residual current protector" specifically comprises: making the thyristor conductive, thereby making the tripping device conductive, and the tripping device disconnecting the B-type residual current protector.

5. The control method according to claim 1, wherein: Num=32.

6. A control device for a type B residual current protective device, characterized in that, comprising the following modules: A preprocessing module is configured to demodulate and sample a waveform of a residual current of the B-type residual current protector, and obtain 2*Num sampling points of the waveform in a sampling period For 2*Num samples a process of fast Fourier transform is performed, and a number of frequency domain components are obtained a number of frequency domain components composition feature vector wherein Num is a natural number; a decision tree processing module, configured to obtain a decision tree model, the decision tree model being trained by a plurality of B-type residual currents and a feature vector corresponding to each B-type residual current; inputting the feature vector Y into the decision tree model, and obtaining a target waveform output by the decision tree model, and obtaining a protection threshold corresponding to the target waveform; determining module, configured to calculate the effective value when X>the protection threshold, disconnecting the B-type residual current protector.

7. The control device according to claim 6, wherein: the B-type residual current protector further comprises a coil driving module, an electromagnetic transformer MI, and a coil L, the coil L being wound on the electromagnetic transformer MI, a first end of the coil L being electrically connected to the coil driving module, and the coil driving module being configured to receive a PWM signal to drive the coil L to complete magnetic modulation of the residual current; the preprocessing module is further configured to collect a voltage value of the residual current from a second end of the coil L at a rising edge of the PWM signal, thereby obtaining the waveform of the residual current, and demodulating and sampling the waveform.

8. The control device of claim 6, wherein The plurality of B-type residual currents at least comprises: AC current, A0° current, A90° current, A135° current, 2PDC current, 3PDC current, SDC current, F current, AC 150 Hz current, AC 400 Hz current, and AC 1000 Hz current.

9. The control device according to claim 6, characterized in that, A silicon controlled rectifier and a tripping device are arranged in the B-type residual current protector. The judging module is further configured to turn on the silicon controlled rectifier, so that the tripping device is energized, and the tripping device disconnects the B-type residual current protector.

10. The control device according to claim 6, characterized in that, Num = 32.

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