Analog quantity acquisition module and test microcomputer protection device

Abstract

This application relates to an analog signal acquisition module and a microcomputer protection device for testing. The voltage acquisition module and current acquisition module in the analog signal acquisition module are used to acquire voltage signals and current signals at the device under test, respectively. A low-pass filter module is connected to the voltage acquisition module and the current-to-voltage conversion circuit to filter the received first voltage signal and second voltage signal, and outputs the filtered voltage signal to the A / D converter. The A / D converter converts the filtered voltage signal into a digital signal and outputs it to the control module. This application improves the sampling accuracy of the analog signal acquisition module by using a low-pass filter module with a high cutoff frequency, an A / D converter with a high sampling rate, and a control module to avoid the influence of frequency aliasing on the sampling accuracy of higher harmonics.

Description

Technical Field

[0001] This application relates to the field of equipment protection technology, and in particular to an analog quantity acquisition module and a microcomputer protection device for testing. Background Technology

[0002] Microcomputer protection devices acquire the voltage and current outputs from the secondary windings of voltage and current transformers in substations, convert analog quantities into digital signals, and calculate parameters such as voltage, current, and impedance for relay protection. They then perform logical judgments on various relay protection components and determine whether to output a trip command based on the judgment results. However, the analog quantity acquisition module in existing microcomputer protection devices has low sampling accuracy and cannot obtain higher harmonic components in the analog quantities for the development of new relay protection principles with stronger functions, thus affecting the safety of the microcomputer protection device. Utility Model Content

[0003] Therefore, it is necessary to provide an analog quantity acquisition module and a microcomputer protection device for testing that can improve sampling accuracy.

[0004] Firstly, this application provides an analog signal acquisition module, including:

[0005] A voltage acquisition module is connected to the device under test (DUT) to acquire the voltage signal at the DUT and output the first voltage signal.

[0006] The current acquisition module is connected to the device under test (DUT) and is used to acquire the current signal at the DUT and output a second voltage signal.

[0007] The low-pass filter module is connected to the voltage acquisition module and the current acquisition module respectively. The low-pass filter module is used to filter the received first voltage signal and second voltage signal and output the filtered voltage signal.

[0008] An A / D converter, connected to a low-pass filter module, is used to convert the filtered voltage signal into a digital signal.

[0009] The control module connects to the A / D converter and is used to receive digital signals.

[0010] In one embodiment, the voltage acquisition module includes a voltage converter.

[0011] In one embodiment, the current acquisition module includes a non-contact current sensor.

[0012] In one embodiment, the non-electrical contact current sensor is a toroidal Rogowski coil current sensor or a clamp-on current sensor.

[0013] In one embodiment, the low-pass filter module includes multiple low-pass filters, which are connected one-to-one with the voltage acquisition module and one-to-one with the current acquisition module.

[0014] The low-pass filter is a second-order RC low-pass filter circuit.

[0015] In one embodiment, the second-order RC low-pass filter circuit includes a first capacitor, a second capacitor, a first resistor, and a second resistor;

[0016] One end of the first resistor is connected to the output terminal of the voltage acquisition module or the current acquisition module. The other end of the first resistor is connected to one end of the first capacitor and one end of the second resistor, respectively. The other end of the first capacitor is used for grounding. The other end of the second resistor is connected to one end of the A / D converter and one end of the second capacitor, respectively. The other end of the second capacitor is used for grounding.

[0017] In one embodiment, the A / D converter is a 16-bit analog-to-digital converter chip.

[0018] In one embodiment, the cutoff frequency of the low-pass filter is 6.4 kHz.

[0019] In one embodiment, the sampling frequency of the control module is 12.8 kHz.

[0020] Secondly, this application also provides a test microcomputer protection device, which includes a main control and communication module, a switch input module, a switch output module, a trip module and a power supply module. The test microcomputer protection device also includes the above-mentioned analog quantity acquisition module.

[0021] The main control and communication module is connected to the analog quantity acquisition module, the digital quantity input module, and the digital quantity output module, respectively. The digital quantity output module is connected to the trip module, and the power supply module is connected to the main control and communication module, the trip module, the digital quantity input module, and the digital quantity output module, respectively.

[0022] In the aforementioned analog signal acquisition module and experimental microcomputer protection device, the voltage acquisition module and current acquisition module in the analog signal acquisition module are both connected to the device under test (DUT) to acquire voltage and current signals from the DUT, respectively. A low-pass filter module is connected to the output terminals of the voltage acquisition module and the current acquisition module to filter the received first and second voltage signals, outputting the filtered voltage signal to the A / D converter. The A / D converter converts the filtered voltage signal into a digital signal and outputs it to the control module. This application, by employing a low-pass filter with a high cutoff frequency, an A / D converter with a high sampling rate, and a control module, can avoid the influence of frequency aliasing on the sampling accuracy of higher harmonics, based on the Nyquist sampling theorem. This improves the sampling accuracy of the analog signal acquisition module, enabling the experimental microcomputer protection device to perform microcomputer protection more accurately and enhancing safety. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a structural block diagram of the analog signal acquisition module in one embodiment;

[0025] Figure 2 This is a schematic diagram of a second-order RC low-pass filter circuit in one embodiment;

[0026] Figure 3 This is a structural block diagram of the analog signal acquisition module in another embodiment;

[0027] Figure 4 This is a structural block diagram of a test microcomputer protection device in one embodiment. Detailed Implementation

[0028] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0030] It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a first resistor, and similarly, a first resistor may be referred to as a first resistor. Both a first resistor and a first resistor are resistors, but they are not the same resistor.

[0031] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0032] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0033] Currently, the protection principle of microprocessor-based protection devices is often based on logical judgment using power frequency quantities. Therefore, an analog low-pass filter is set in the voltage and current sampling circuit of the analog quantity acquisition module to filter out high-frequency components in the voltage and current signals. The loads of electrified railway traction power supply systems are mainly AC-DC and AC-DC-AC electric locomotives or EMUs. Under different operating conditions, the load current contains a certain amount of low-order and high-order harmonics. To reduce hardware and software requirements, the analog low-pass filter circuits in the current electrified railway microcomputer protection devices have low cutoff frequencies and low sampling frequencies, which meet the needs of measuring the 2nd, 3rd, 5th, and 7th harmonics. However, sampling for higher harmonics will result in frequency aliasing, causing data processing distortion. Traditional analog acquisition modules also suffer from low sampling accuracy, affecting the accuracy of the logic judgment of the microcomputer protection device and thus reducing safety. Therefore, the relay protection principle utilizing the characteristics of higher harmonic components of load current cannot be directly implemented in existing microcomputer protection devices. In addition, the current circuit of the experimental microcomputer protection device is directly connected in series with the secondary current circuit of the existing operating substation, which poses certain risks and low safety.

[0034] The analog signal acquisition module provided in this application adopts a low-pass filter module with a high cutoff frequency, an A / D converter with a high sampling rate, and a control module. According to the Nyquist sampling theorem, it can avoid the influence of frequency aliasing on the sampling accuracy of higher harmonics, thereby improving the sampling accuracy. This, in turn, improves the accuracy of the logic judgment of the microcomputer protection device equipped with the analog signal acquisition module, enabling it to perform microcomputer protection more accurately and improving safety.

[0035] In one exemplary embodiment, such as Figure 1 As shown, this application provides an analog signal acquisition module, including:

[0036] Voltage acquisition module 110 is connected to the device under test and is used to acquire the voltage signal at the device under test and output the first voltage signal;

[0037] The current acquisition module 120 is connected to the device under test (DUT) and is used to acquire the current signal at the DUT and output a second voltage signal.

[0038] The low-pass filter module 130 is connected to the voltage acquisition module 110 and the current acquisition module 120 respectively. The low-pass filter module 130 is used to filter the received first voltage signal and second voltage signal and output the filtered voltage signal.

[0039] A / D converter 140 is connected to low-pass filter module 130. A / D converter 140 is used to convert the filtered voltage signal into a digital signal.

[0040] The control module 150 is connected to the A / D converter 140 and is used to receive digital signals.

[0041] The type and number of devices to be tested can be set according to the actual situation, and are not limited in this embodiment.

[0042] Specifically, such as Figure 1As shown, the voltage acquisition module 110 may include multiple devices for acquiring voltage signals to acquire voltage signals from each device under test and output a first voltage signal to the low-pass filter module 130; the current acquisition module 120 may include multiple devices for acquiring current signals to acquire current signals from each device under test and output a second voltage signal to the low-pass filter module 130; the low-pass filter module 130 is connected to both the voltage acquisition module 110 and the current acquisition module 120, and filters the received voltage signals to remove high-frequency components from the voltage signals. The low-pass filter module 130 has a high cutoff frequency, which can effectively prevent high-frequency noise and harmonic interference from interfering with the sampling process. The low-pass filter module 130 outputs the filtered voltage signal to the A / D converter 140. The A / D converter 140 converts the filtered voltage signal into a digital signal that the control module 150 can recognize. The control module 150 receives the digital signal and completes the acquisition of data (analog quantity). The A / D converter 140 and the control module 150 have high sampling rates, which expands the frequency range of reliable sampling, effectively avoids the impact of frequency aliasing on the sampling accuracy of higher harmonics, and improves the sampling accuracy of the analog quantity acquisition module.

[0043] The aforementioned analog signal acquisition modules, including the voltage and current acquisition modules, are connected to the device under test (DUT). A low-pass filter module is connected to both the voltage and current acquisition modules. An A / D converter is connected to the low-pass filter module, and a control module is connected to the A / D converter. By employing a low-pass filter module with a high cutoff frequency, an A / D converter with a high sampling rate, and a control module, the influence of frequency aliasing on the sampling accuracy of higher harmonics can be avoided, according to the Nyquist sampling theorem. This improves sampling accuracy and, consequently, enhances the accuracy of the logic judgment of the experimental microcomputer protection device equipped with the analog signal acquisition module, enabling more accurate microcomputer protection and improving safety.

[0044] In one embodiment, the voltage acquisition module includes a voltage converter.

[0045] Specifically, the voltage acquisition module includes a voltage converter for acquiring voltage signals from the device under test. The number of voltage converters can be set according to actual conditions and is not limited in this embodiment.

[0046] For example, taking a voltage acquisition module including 4 voltage converters and a substation voltage transformer as the device under test, the following explanation is given. The input terminal of each voltage converter is directly connected to the secondary circuit of the substation voltage transformer and outputs an AC voltage signal of 0-3.53V. It should be noted that the model of the voltage converter can be ZM-BPT.

[0047] In one embodiment, the current acquisition module includes a non-contact current sensor.

[0048] It should be noted that when verifying the new principle of relay protection during on-site testing, the test microcomputer protection device needs to be connected to the existing operating relay protection system to collect the secondary circuit voltage and current. In order to ensure the safety of the existing relay protection system, the secondary circuit voltage of the test microcomputer protection device adopts the terminal parallel acquisition method, and the secondary circuit current adopts the non-contact induction acquisition method.

[0049] Specifically, the current acquisition module includes a non-electrical contact current sensor for acquiring current signals at the device under test. The number of non-electrical contact current sensors can be set according to actual conditions and is not limited in this embodiment. The non-electrical contact current sensor does not need to be directly connected to the secondary current circuit of the existing substation, which improves safety.

[0050] For example, taking a substation current transformer as the device under test, the primary coil of the non-contact current sensor is electromagnetically coupled to the secondary circuit of the substation current transformer, outputting an AC voltage signal of 0~3.53V. That is, the non-contact current sensor does not need to be connected in series with the secondary circuit of the substation current transformer, and will not cause an open circuit in the existing current secondary circuit of the substation, thus improving the safety of the microprocessor protection device and the substation secondary equipment.

[0051] In this embodiment, a non-contact current sensor is used to collect the current signal at the device under test, which effectively avoids direct connection with the device under test and improves safety.

[0052] In one embodiment, the non-electrical contact current sensor is a toroidal Rogowski coil current sensor or a clamp-on current sensor.

[0053] Specifically, taking a current acquisition module consisting of four clamp-on current sensors and a substation voltage transformer as an example, each clamp-on current sensor senses the secondary circuit current of the substation current transformer and outputs an AC voltage signal of 0~3.53V. It should be noted that the model of the clamp-on current sensor can be FR008.

[0054] In one embodiment, the low-pass filter module includes multiple low-pass filters, which are connected one-to-one with the voltage acquisition module and one-to-one with the current acquisition module.

[0055] The low-pass filter is a second-order RC low-pass filter circuit.

[0056] Specifically, the number of low-pass filters in the low-pass filter module can be set according to the actual situation, as long as it can meet the requirement that each voltage and current acquisition module is connected to a low-pass filter. The low-pass filter can be a second-order RC low-pass filter circuit with a high cutoff frequency, which can effectively prevent high-frequency noise and harmonic interference from interfering with the sampling process.

[0057] For example, the low-pass filter can also be a first-order RC low-pass filter circuit with a high cutoff frequency.

[0058] It should be noted that frequency aliasing is a type of signal distortion that can occur during digital signal sampling. Frequency aliasing occurs when the sampling frequency is less than twice the highest frequency component in the signal (according to the Nyquist sampling theorem). Low-pass filters with high cutoff frequencies can significantly attenuate frequency components above the Nyquist frequency, i.e., pre-suppress high-frequency noise and prevent sampling distortion caused by higher harmonics.

[0059] It is understood that the low-pass filter described above can also take other forms, and is not limited to the forms mentioned in the above embodiments, as long as it can achieve the function of filtering the received voltage signal.

[0060] In this embodiment, by setting a second-order RC low-pass filter circuit with a high cutoff frequency, according to the Nyquist sampling theorem, the influence of frequency aliasing on the sampling accuracy of higher harmonics can be avoided, thereby improving the sampling accuracy.

[0061] In one embodiment, such as Figure 2 As shown, the second-order RC low-pass filter circuit includes a first capacitor C1, a second capacitor C2, a first resistor R1, and a second resistor R2.

[0062] One end of the first resistor R1 is connected to the current-to-voltage conversion circuit. The other end of the first resistor R1 is connected to one end of the first capacitor C1 and one end of the second resistor R2. The other end of the first capacitor C1 is used for grounding. The other end of the second resistor R2 is connected to the A / D converter and one end of the second capacitor C2. The other end of the second capacitor C2 is used for grounding.

[0063] Specifically, such as Figure 2 As shown, the second-order RC low-pass filter circuit includes a first capacitor C1, a second capacitor C2, a first resistor R1, and a second resistor R2 to filter the received voltage signal and output the filtered voltage signal to the A / D converter.

[0064] For example, such as Figure 2As shown, the first resistor R1 and the second resistor R2 can both be set to 910Ω, the first capacitor C1 and the second capacitor C2 can both be set to 0.01μF, and the cutoff frequency f is set to 6.4kHz. This is used to filter out noise interference signals in the voltage signal, while also meeting the requirement of collecting power frequency current from the fundamental wave to the 64th higher harmonic component, avoiding the impact of frequency aliasing on the sampling accuracy of higher harmonics, thereby improving the sampling accuracy.

[0065] In one embodiment, the A / D converter is a 16-bit analog-to-digital converter chip.

[0066] Specifically, the sampling range of the 16-bit analog-to-digital converter chip is AC 0-5V, and it has 8 channels of synchronous sampling and analog-to-digital conversion functions. The model of the 16-bit analog-to-digital converter chip can be ADS8688IDBT, and the sampling bit width is 16 bits.

[0067] It should be noted that by using a 16-bit analog-to-digital converter chip to convert the filtered voltage signal into a digital signal, quantization error can be reduced, signal reconstruction accuracy can be improved, and the spectral characteristics of complex signals can be captured and reconstructed more accurately, thereby effectively suppressing the adverse effects of frequency aliasing on the sampling accuracy of higher harmonics.

[0068] In this embodiment, a 16-bit analog-to-digital converter chip is used to convert the filtered voltage signal into a digital signal. Through more refined signal quantization, the spectral characteristics of complex signals can be captured and reconstructed more accurately, thereby effectively suppressing the adverse effects of frequency aliasing on the sampling accuracy of higher harmonics and improving sampling accuracy.

[0069] In one embodiment, the cutoff frequency of the low-pass filter is 6.4 kHz.

[0070] Specifically, the low-pass filter consists of resistors and capacitors, with a cutoff frequency set to 6.4kHz. Based on the Nyquist sampling theorem, it meets the requirement of collecting power frequency current from the fundamental wave to the 64th higher harmonic component, so as to avoid the influence of frequency aliasing on the sampling accuracy of higher harmonics, thereby improving the accuracy of logic judgment of the microcomputer protection device, enabling more accurate microcomputer protection and improving safety.

[0071] In one embodiment, the sampling frequency of the control module is 12.8 kHz.

[0072] The type of control module can be set according to the actual situation. In this embodiment, the control module is an FPGA module as an example.

[0073] Specifically, the sampling frequency of the FPGA module is 12.8kHz, and the model of the FPGA module can be XC7Z010-2CLG400I.

[0074] In this embodiment, the sampling frequency of the control module is 12.8kHz. The high sampling frequency can significantly expand the frequency range of reliable sampling, reduce the probability of frequency aliasing, and effectively suppress the adverse effects of frequency aliasing on the sampling accuracy of higher harmonics. This improves the accuracy of the logic judgment of the microcomputer protection device, enables more accurate microcomputer protection, and enhances safety.

[0075] To facilitate understanding by those skilled in the art, the analog signal acquisition module will be explained below with reference to a specific example, such as... Figure 3 As shown, the low-pass filter module can be an analog low-pass filter circuit 3, the A / D converter can be an A / D conversion circuit 4, and the control module can be an FPGA module 5.

[0076] like Figure 3 As shown, the analog acquisition module includes a voltage converter 1, a non-electrical contact current sensor 2, an analog low-pass filter circuit 3, an A / D conversion circuit 4, and an FPGA module 5.

[0077] The input terminal of voltage converter 1 is directly connected to the output of the secondary circuit (device under test) of the voltage transformer in the substation, and is used to output an AC voltage signal of 0-3.53V. The output terminal is connected in parallel with the low-pass filter circuit 3.

[0078] The non-electrical contact current sensor 2 is an external device of the microcomputer protection device for testing. It is a component of the analog quantity acquisition module. The primary side of the non-electrical contact current sensor 2 is electromagnetically coupled to the secondary circuit of the current transformer in the substation, and outputs an AC voltage signal of 0-3.53V. The output terminal is connected in parallel with the low-pass filter circuit 3.

[0079] The analog low-pass filter circuit 3 consists of resistors and capacitors, with a cutoff frequency set to 6.4kHz. Based on the Nyquist sampling theorem, it meets the requirement of collecting power frequency current from the fundamental wave to the 64th higher harmonic component. The input terminal of the analog low-pass filter circuit 3 is electrically connected to the output of the voltage converter 1 and to the output terminal of the non-contact current sensor 2. The output terminal of the analog low-pass filter circuit 3 is electrically connected to the input terminal of the A / D conversion circuit 4.

[0080] The A / D conversion circuit 4 has a sampling bit depth of 16 bits. Its input terminal is electrically connected to the output terminal of the analog low-pass filter circuit 3, which is responsible for converting analog signals into digital signals. The digital output circuit of the A / D conversion circuit 3 is electrically connected to the FPGA module 5.

[0081] FPGA module 5 outputs control signals to A / D conversion circuit 4, with the sampling frequency set to 12.8kHz, and receives the digital output from A / D conversion circuit 4.

[0082] The DC power supply for the A / D conversion circuit 4 and the FPGA module 5 comes from the power supply module of the microcomputer protection device for the test.

[0083] The analog signal acquisition module provided in this application features an analog low-pass filter circuit with a high cutoff frequency, an A / D conversion circuit with a high sampling rate, and an FPGA module. According to the Nyquist sampling theorem, the influence of frequency aliasing on the sampling accuracy of higher harmonics can be avoided, thus improving the sampling accuracy of the analog signal acquisition module. At the same time, by using a non-contact current sensor, which does not need to be connected in series with the secondary circuit of the substation current transformer, the existing current secondary circuit of the substation will not be opened, thus improving the safety of the microprocessor protection device and the substation secondary equipment.

[0084] In one exemplary embodiment, this application also provides a test microcomputer protection device, such as... Figure 4 As shown, the test microcomputer protection device includes a main control and communication module, a digital input module, a digital output module, a trip module, and a power supply module. The test microcomputer protection device also includes the aforementioned analog quantity acquisition module. The main control and communication module is connected to the analog quantity acquisition module, the digital input module, and the digital output module, respectively. The digital output module is connected to the trip module, and the power supply module is connected to the main control and communication module, the trip module, the digital input module, and the digital output module, respectively.

[0085] Among them, such as Figure 4 As shown, the functions and specific structures of the main control and communication module, the digital input module, the digital output module, the trip module, and the power supply module are existing technologies and can be set according to actual conditions. They will not be described in detail in this embodiment.

[0086] Specifically, such as Figure 4 As shown, the experimental microcomputer protection device includes the aforementioned analog quantity acquisition module, which improves the accuracy of the logical judgment of the experimental microcomputer protection device, enabling it to perform microcomputer protection more accurately, thereby improving safety.

[0087] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0088] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0089] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An analog signal acquisition module, characterized in that, include: A voltage acquisition module is connected to the device under test (DUT) and is used to acquire the voltage signal at the DUT and output a first voltage signal. A current acquisition module is connected to the device under test (DUT) and is used to acquire the current signal at the DUT and output a second voltage signal. A low-pass filter module is connected to the voltage acquisition module and the current acquisition module respectively. The low-pass filter module is used to filter the received first voltage signal and the second voltage signal and output the filtered voltage signal. An A / D converter is connected to the low-pass filter module, and the A / D converter is used to convert the filtered voltage signal into a digital signal. A control module is connected to the A / D converter, and the control module is used to receive the digital signal.

2. The analog signal acquisition module according to claim 1, characterized in that, The voltage acquisition module includes a voltage converter.

3. The analog signal acquisition module according to claim 1, characterized in that, The current acquisition module includes a non-contact current sensor.

4. The analog quantity acquisition module according to claim 3, characterized in that, The non-electrical contact current sensor is a toroidal Rogowski coil current sensor or a clamp-on current sensor.

5. The analog signal acquisition module according to claim 1, characterized in that, The low-pass filter module includes multiple low-pass filters, each of which is connected to the voltage acquisition module in a one-to-one correspondence, and each of which is also connected to the current acquisition module in a one-to-one correspondence. The low-pass filter is a second-order RC low-pass filter circuit.

6. The analog quantity acquisition module according to claim 5, characterized in that, The second-order RC low-pass filter circuit includes a first capacitor, a second capacitor, a first resistor, and a second resistor. One end of the first resistor is connected to the output terminal of the voltage acquisition module or the current acquisition module. The other end of the first resistor is connected to one end of the first capacitor and one end of the second resistor, respectively. The other end of the first capacitor is used for grounding. The other end of the second resistor is connected to the A / D converter and one end of the second capacitor, respectively. The other end of the second capacitor is used for grounding.

7. The analog quantity acquisition module according to claim 5, characterized in that, The cutoff frequency of the low-pass filter is 6.4 kHz.

8. The analog signal acquisition module according to claim 1, characterized in that, The A / D converter is a 16-bit analog-to-digital converter chip.

9. The analog signal acquisition module according to claim 1, characterized in that, The sampling frequency of the control module is 12.8 kHz.

10. A microcomputer protection device for testing, characterized in that, The test microcomputer protection device includes a main control and communication module, a digital input module, a digital output module, a trip module, and a power supply module. The test microcomputer protection device also includes an analog quantity acquisition module as described in any one of claims 1 to 9. The main control and communication module is connected to the analog quantity acquisition module, the digital quantity input module and the digital quantity output module, respectively. The digital quantity output module is connected to the trip module. The power supply module is connected to the main control and communication module, the trip module, the digital quantity input module and the digital quantity output module, respectively.

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