Sampling precision improving system and method based on amplitude and frequency dimension conversion

Abstract

The invention discloses a sampling precision improving system based on amplitude and frequency dimension conversion. The sampling precision improving system comprises a front-end sampling circuit, a fundamental wave low-pass filter, an MCU controller and a plurality of groups of tunable band-pass filters and V / F conversion circuits, the output end of the front-end sampling circuit is electrically connected with the input ends of the fundamental wave low-pass filter and the plurality of groups of tunable band-pass filters, and the output ends of the fundamental wave low-pass filter and the plurality of groups of tunable band-pass filters are electrically connected with the input ends of different V / F conversion circuits in sequence. The output ends of the V / F conversion circuits are electrically connected with the input end of the MCU controller, and the MCU controller is electrically connected with the tunable band-pass filter. The invention further discloses a sampling precision improving method based on amplitude and frequency dimension conversion. The technical problem that the sampling and measuring precision of voltage, current and the like in an existing power system is low is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a sampling accuracy improvement system and method based on amplitude and frequency dimension conversion. Background Art

[0002] In the operation of modern power systems, voltage and current measurement is a crucial link, and its accuracy directly affects the operating efficiency, safety performance, and power quality assessment of the entire power system. Traditional voltage measurement methods usually rely on analog-to-digital converters for sampling and quantization. However, due to hardware limitations such as sampling frequency, resolution, and bandwidth, as well as the influence of various environmental factors such as electromagnetic interference and power supply noise, it is more difficult to accurately measure voltage. In particular, in situations where high-precision measurement is required, traditional methods often fail to meet the requirements. In addition, high-precision analog-to-digital converters are relatively expensive, resulting in high equipment costs. Therefore, it is urgent to propose a sampling accuracy improvement system and method based on amplitude and frequency dimension conversion to solve the technical problem of low sampling and measurement accuracy of voltage, current, etc. in existing power systems. Summary of the Invention

[0003] The main purpose of the present invention is to propose a sampling accuracy improvement system and method based on amplitude and frequency dimension conversion, aiming to solve the technical problem of low sampling measurement accuracy of voltage, current, etc. in existing power systems.

[0004] To achieve the above objectives, the present invention provides a sampling accuracy improvement system based on amplitude and frequency dimension conversion, wherein the sampling accuracy improvement system based on amplitude and frequency dimension conversion includes:

[0005] A front-end sampling circuit, a fundamental low-pass filter, an MCU controller, and several groups of tunable band-pass filters and a V / F conversion circuit; the output end of the front-end sampling circuit is electrically connected to the input ends of the fundamental low-pass filter and several groups of tunable band-pass filters respectively, the output ends of the fundamental low-pass filter and several groups of tunable band-pass filters are electrically connected to the input ends of different V / F conversion circuits in sequence, the output ends of several groups of the V / F conversion circuits are electrically connected to the input end of the MCU controller, and the MCU controller is electrically connected to the tunable band-pass filters.

[0006] In one of the preferred solutions, the tunable bandpass filter adopts an active second-order bandpass filter with a controllable resonant frequency using a digital potentiometer.

[0007] In one preferred embodiment, the tunable bandpass filter includes a sampling resistor R0, a digital potentiometer R1, a capacitor C1, a capacitor C2, a digital potentiometer R2, and an active operational amplifier U1; one end of the sampling resistor R0 is respectively connected to the front-end sampling circuit and the digital potentiometer R1, the digital potentiometer R1 is respectively connected to the capacitor C1 and the capacitor C2, the other end of the capacitor C1 is respectively connected to the digital potentiometer R2 and the output end of the active operational amplifier U1, the other end of the capacitor C2 is respectively connected to the other end of the digital potentiometer R2 and the negative input end of the active operational amplifier U1, the positive input end of the active operational amplifier U1 and the other end of the sampling resistor R0 are grounded, and the output end of the active operational amplifier U1 is connected to the post-stage V / F conversion circuit.

[0008] In one preferred solution, the digital potentiometer R1 and the digital potentiometer R2 are communicatively connected to the MCU controller via an I2C serial port.

[0009] In one of the preferred solutions, the V / F conversion circuit is composed of a reference voltage source, a V / F conversion chip, a bypass capacitor and a crystal oscillator source.

[0010] A method for improving the sampling accuracy of the system based on amplitude and frequency dimension conversion includes the following steps:

[0011] S1. Start the system, and the front-end sampling circuit collects the voltage / current analog sampling signal;

[0012] S2. Convert the voltage / current analog sampling signal to obtain a sampled voltage signal, group the sampled voltage signal according to the number of harmonics, and sequentially control a number of groups of tunable bandpass filters with the same number of groups to process the sampled voltage signal, and output harmonic signals of different harmonic groups;

[0013] S3, performing harmonic conversion through a V / F conversion circuit corresponding to a plurality of groups of tunable bandpass filters, and outputting frequency values of different harmonic groups;

[0014] S4. The MCU controller calculates the amplitude of each harmonic according to the obtained frequency values of different harmonic groups.

[0015] In one preferred solution, the frequency value of step S3 is:

[0016]

[0017] Among them, F out is the frequency value, V int is the initial amplitude of the voltage / current analog sampling signal collected by the front-end acquisition circuit, K1 is the full-scale value of the input voltage of the V / F conversion circuit, and F clock is the reference frequency value.

[0018] In one preferred solution, the amplitude of each harmonic in step S3 is:

[0019]

[0020] Among them, V n is the amplitude of each harmonic, K1 is the full-scale value of the input voltage of the V / F conversion circuit, K2 is the calibration coefficient, F out is the frequency value of different harmonic groups, that is, the frequency value of each harmonic, F clock is the reference frequency value.

[0021] In the above technical solution of the present invention, the sampling accuracy improvement system based on amplitude and frequency dimension conversion includes: a front-end sampling circuit, a fundamental low-pass filter, an MCU controller, and several groups of tunable band-pass filters and a V / F conversion circuit; the output end of the front-end sampling circuit is electrically connected to the input end of the fundamental low-pass filter and several groups of tunable band-pass filters respectively, the output end of the fundamental low-pass filter and several groups of tunable band-pass filters are electrically connected to the input end of different V / F conversion circuits in turn, the output end of several groups of the V / F conversion circuits is electrically connected to the input end of the MCU controller, and the MCU controller is electrically connected to the tunable band-pass filter. The present invention solves the technical problem of low sampling and measurement accuracy of voltage, current, etc. in existing power systems.

[0022] In the present invention, the voltage / current analog sampling signal is converted from the time domain space to the frequency domain space for analysis and processing. In the frequency domain space, the various frequency components of the voltage / current analog sampling signal are clearly displayed. By filtering and extracting specific frequency components, the frequency signal of the grid fundamental voltage is accurately obtained. At the same time, by performing amplitude modulation or demodulation on the voltage / current analog sampling signal, the intensity change of the signal can be effectively converted into a frequency form that is easy to detect and analyze. By utilizing the high-resolution characteristic of frequency, accurate measurement of the voltage amplitude is achieved, reducing the error caused by single-dimensional measurement, and effectively eliminating measurement deviations caused by equipment accuracy limitations and environmental interference.

[0023] In the present invention, the signal of the tunable bandpass filter is converted into a square wave signal with variable frequency, and the frequency value and the signal amplitude are proportionally transformed through an algorithm. The precise amplitude of the voltage / current analog sampling signal can be calculated through the frequency value. Since the frequency resolution can reach 1 / Mhz, which is equivalent to twice, the number of bits of the AD chip or metering chip currently used for electric energy metering is generally 16 bits. The amplitude resolution obtained by the present invention is 16 times that of the AD chip or metering chip, which is an order of magnitude higher, and the cost is low, thereby achieving a significant improvement in the voltage / current measurement accuracy, ensuring effective management of the operating efficiency and safety of the power system, and the cost is much lower than that of the AD chip, thereby reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 This is a first schematic diagram of a sampling accuracy improvement system based on amplitude and frequency dimension conversion according to an embodiment of the present invention;

[0026] Figure 2 This is a second schematic diagram of a sampling accuracy improvement system based on amplitude and frequency dimension conversion according to an embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of a tunable bandpass filter according to an embodiment of the present invention;

[0028] Figure 4 Schematic diagram of a V / F conversion chip according to an embodiment of the present invention;

[0029] Figure 5 This is a first schematic diagram of a method for improving sampling accuracy based on amplitude and frequency dimension conversion according to an embodiment of the present invention;

[0030] Figure 6 This is a second schematic diagram of a method for improving sampling accuracy based on amplitude and frequency dimension conversion according to an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of a flow chart of time-sharing control of a tunable bandpass filter according to an embodiment of the present invention;

[0032] Figure 8 This is a flow chart of a method for accurately identifying the frequency of an IO port signal according to an embodiment of the present invention.

[0033] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0036] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of these features.

[0037] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] See also Figures 1-4 According to one aspect of the present invention, the present invention provides a sampling accuracy improvement system based on amplitude and frequency dimensional conversion, wherein the sampling accuracy improvement system based on amplitude and frequency dimensional conversion includes: a front-end sampling circuit, a fundamental low-pass filter, an MCU controller, and several groups of tunable band-pass filters and a V / F conversion circuit; the output end of the front-end sampling circuit is electrically connected to the input end of the fundamental low-pass filter and several groups of tunable band-pass filters respectively, the output ends of the fundamental low-pass filter and several groups of tunable band-pass filters are electrically connected to the input ends of different V / F conversion circuits in turn, the output ends of several groups of the V / F conversion circuits are electrically connected to the input end of the MCU controller, and the MCU controller is electrically connected to the tunable band-pass filter.

[0039] Specifically, in this embodiment, the bottom layer of the sampling accuracy improvement system based on amplitude and frequency dimension conversion is the voltage and current sampling layer. The secondary signal of the front-end sampling circuit is first converted into a voltage signal through a sampling resistor. If the front-end sampling circuit adopts a current transformer, the signal needs to be converted into a voltage signal. If the front-end sampling circuit adopts a voltage transformer, the sampling resistor is not required to convert the signal into a voltage signal. The signal is filtered out of high-frequency interference and EMC protection through a bidirectional transient suppressor and an RC filter circuit, mainly filtering out interference above 20 kHz. Several tunable band-pass filters and a fundamental low-pass filter are connected in parallel after the front-end sampling circuit. The tunable band-pass filters are controlled by an MCU and output harmonics of different orders in a time-sharing manner. Then, a V / F conversion circuit is designed for each tunable band-pass filter. The MCU controller has multiple IO ports, and the IO ports have external interrupt functions. The MCU controller has a timer and interrupt functions inside, which can count the pulse signals on the IO ports. The MCU controller has an IIC communication function.

[0040] Specifically, in this embodiment, see Figure 3 The tunable bandpass filter adopts an active second-order bandpass filter with a controllable resonant frequency of a digital potentiometer; the tunable bandpass filter includes a sampling resistor R0, a digital potentiometer R1, a capacitor C1, a capacitor C2, a digital potentiometer R2, and an active operational amplifier U1; one end of the sampling resistor R0 is respectively connected to the front-end sampling circuit and the digital potentiometer R1, the digital potentiometer R1 is respectively connected to the capacitor C1 and the capacitor C2, the other end of the capacitor C1 is respectively connected to the digital potentiometer R2 and the output end of the active operational amplifier U1, the other end of the capacitor C2 is respectively connected to the other end of the digital potentiometer R2 and the negative input end of the active operational amplifier U1, the positive input end of the active operational amplifier U1 and the other end of the sampling resistor R0 are grounded, and the output end of the active operational amplifier U1 is connected to the post-stage V / F conversion circuit.

[0041] Specifically, in this embodiment, the digital potentiometer R1 and the digital potentiometer R2 are connected to the MCU controller through the I2C serial port, and receive the instructions for adjusting the R value from the MCU controller in a time-sharing manner. The R value is adjustable, thereby changing the resonance point of the entire filter, thereby achieving the purpose of time-sharing measurement of different harmonics.

[0042] Specifically, in this embodiment, see Figure 4The V / F conversion circuit consists of a reference voltage source, a V / F conversion chip, a bypass capacitor, and a crystal oscillator source; the V / F conversion chip is internally composed of an integrator, a comparator, an AND gate, a trigger, a latch, and a square wave transmission gate switch tube; the analog voltage / current signal enters the V / F control chip, where it is stored and shaped by Rin and Cin, maintained in state by the integrator, and then compared with the comparator for output. At the beat of an external rated reference frequency, the signal enters the trigger, which, based on the external rated reference frequency, superimposes and outputs a carrier square wave signal with the amplitude characteristics of the external measured voltage.

[0043] According to another aspect of the present invention, see Figure 5 The present invention provides a method for improving sampling accuracy based on amplitude and frequency dimension conversion, wherein the method for improving sampling accuracy based on amplitude and frequency dimension conversion comprises the following steps:

[0044] S1. Start the system, and the front-end sampling circuit collects the voltage / current analog sampling signal;

[0045] S2. Convert the voltage / current analog sampling signal to obtain a sampled voltage signal, group the sampled voltage signal according to the number of harmonics, and sequentially control a number of groups of tunable bandpass filters with the same number of groups to process the sampled voltage signal, and output harmonic signals of different harmonic groups;

[0046] S3, performing harmonic conversion through a V / F conversion circuit corresponding to a plurality of groups of tunable bandpass filters, and outputting frequency values of different harmonic groups;

[0047] S4. The MCU controller calculates the amplitude of each harmonic according to the obtained frequency values of different harmonic groups.

[0048] Specifically, in this embodiment, the frequency value of step S3 is:

[0049]

[0050] Among them, F out is the frequency value, V int is the initial amplitude of the voltage / current analog sampling signal collected by the front-end acquisition circuit, K1 is the full-scale value of the input voltage of the V / F conversion circuit, and F clock is the reference frequency value.

[0051] Specifically, in this embodiment, the voltage / current amplitude of each harmonic in step S3 is:

[0052]

[0053] Among them, V nis the amplitude of each harmonic, K1 is the full-scale value of the input voltage of the V / F conversion circuit, K2 is the calibration coefficient, F out is the frequency value of different harmonic groups, that is, the frequency value of each harmonic, F clock is the reference frequency value.

[0054] Specifically, in this embodiment, see Figure 7 , the total number of measured harmonics is divided into a range. If the harmonics within 50 times (excluding even harmonics) are measured according to the requirements, the number of harmonics to be measured will be divided into 5 groups according to 3-11 times, 13-21 times, 23-31 times, 33-41 times, and 43-51 times. Each group measures 5 harmonics. The divided groups are set as N1, N2, N3, N4, and N5 in sequence. Each group has an independent hardware measurement channel, that is, a group of tunable band-pass filters and a group of V / F conversion circuits are set accordingly. The five groups of hardware channels are connected in parallel to the input of the signal after high-frequency filtering, and the signal is detected at the same time. The I2C ports of the two digital potentiometers of the tunable band-pass filters of each group are connected to the same I2C port of the MCU controller. The address of each digital potentiometer is different. If there are more than 8 addresses, the MCU controller allocates two I2C ports. The MCU controller will time-share each I2C line according to the address. Send instructions to the corresponding digital potentiometer according to the address. For example, send commands to the addresses of digital potentiometers R1 and R2, adjust digital potentiometers R1 and R2, so that the filter is located at the 3rd resonance point, and then query the interrupt register of IO1 to see if the received data has been updated. If not, execute the instruction again. If so, send commands to the addresses of digital potentiometers 1 and 2, adjust resistors 1 and 2, so that the filter is located at the 5th resonance point, and so on, and execute the 3rd to 11th harmonic sampling in sequence; the time-sharing interval of each digital potentiometer is 200ms, so the total sampling time of each group of 5 digital point devices is 1s, and a cycle is performed every 1s, and sampling is performed continuously. The fixed-frequency sampling time of each digital potentiometer is 200ms, 10 cycles, and every 10 cycles represents the fixed sampling time of a harmonic, ensuring accurate analysis of each harmonic data, and the update time of the measurement data is 1s.

[0055] Specifically, in this embodiment, see Figure 8The sampling signal is filtered at high frequency and given to 5 parallel tunable band-pass filters and 1 fundamental low-pass filter. It is divided into fundamental wave and 3-51 harmonics, and the harmonic signals of different orders are collected in time-sharing order. Then, they are converted to the corresponding V / F conversion circuit. The pulses of each group of digital signals after conversion are transmitted to the MCU controller through the IO port. The MCU controller calculates each channel, every 10 cycles, and each harmonic through interrupts and counters. The MCU controller calculates the amplitude of each harmonic by high-precision identification of the IO port signal frequency value; the MCU controller calls the measurement data storage register and queries the measurement data storage register n to see whether the received data has been updated. If not, the instruction is executed again. If so, the measurement data calculation Vn is called, and then the voltage and current measurement data are identified, compared, stored, and uploaded. This process is repeated to complete the calculation, identification, comparison, storage, and upload of the fundamental wave and 3-51 harmonic measurement data.

[0056] Specifically, in this embodiment, see Figure 6 First, the time-sharing control tunable band-pass filter is called to control the five parallel tunable band-pass filters in turn. The six IO ports are set to external interrupt mode. The interrupt registers of IO0-IO5 can be queried at the same time to see if the received data has been updated. When the data is updated and received, the V / F conversion circuit and MCU controller are called again to calculate, identify, compare, store and upload the voltage and current measurement data. After completion, the next round of data sampling and processing is carried out.

[0057] Specifically, in this embodiment, the system of the present invention does not need to be equipped with an AD chip or a metering chip. Compared with the conventional measurement method using a metering chip or an AD chip, the present invention can improve the measurement accuracy by 1-2 orders of magnitude, from a 0.5-level metering accuracy to a 0.05 to 0.005-level metering accuracy, and reduces the requirements for key core components, reduces costs, and at the same time, improves the measurement accuracy of voltage and current amplitudes.

[0058] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present description and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A sampling accuracy improvement system based on amplitude and frequency dimension conversion, characterized in that: include: A front-end sampling circuit, a fundamental low-pass filter, an MCU controller, and several groups of tunable band-pass filters and a V / F conversion circuit; the output end of the front-end sampling circuit is electrically connected to the input ends of the fundamental low-pass filter and several groups of tunable band-pass filters respectively, the output ends of the fundamental low-pass filter and several groups of tunable band-pass filters are electrically connected to the input ends of different V / F conversion circuits in sequence, the output ends of several groups of the V / F conversion circuits are electrically connected to the input end of the MCU controller, and the MCU controller is electrically connected to the tunable band-pass filters.

2. A sampling accuracy improvement system based on amplitude and frequency dimension conversion according to claim 1, characterized in that: The tunable bandpass filter adopts an active second-order bandpass filter with a controllable resonant frequency using a digital potentiometer.

3. The sampling accuracy improvement system based on amplitude and frequency dimension conversion according to claim 2 is characterized in that: The tunable bandpass filter includes a sampling resistor R0, a digital potentiometer R1, a capacitor C1, a capacitor C2, a digital potentiometer R2, and an active operational amplifier U1; one end of the sampling resistor R0 is respectively connected to the front-end sampling circuit and the digital potentiometer R1, the digital potentiometer R1 is respectively connected to the capacitor C1 and the capacitor C2, the other end of the capacitor C1 is respectively connected to the digital potentiometer R2 and the output end of the active operational amplifier U1, the other end of the capacitor C2 is respectively connected to the other end of the digital potentiometer R2 and the negative input end of the active operational amplifier U1, the positive input end of the active operational amplifier U1 and the other end of the sampling resistor R0 are grounded, and the output end of the active operational amplifier U1 is connected to the post-stage V / F conversion circuit.

4. The sampling accuracy improvement system based on amplitude and frequency dimension conversion according to claim 3 is characterized in that: The digital potentiometer R1 and the digital potentiometer R2 are connected to the MCU controller via an I2C serial port.

5. A sampling accuracy improvement system based on amplitude and frequency dimension conversion according to any one of claims 1 to 4, characterized in that: The V / F conversion circuit is composed of a reference voltage source, a V / F conversion chip, a bypass capacitor and a crystal oscillator source.

6. A method comprising a sampling accuracy improvement system based on amplitude and frequency dimension conversion according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Start the system, and the front-end sampling circuit collects the voltage / current analog sampling signal; S2. Convert the voltage / current analog sampling signal to obtain a sampled voltage signal, group the sampled voltage signal according to the number of harmonics, and sequentially control a number of groups of tunable bandpass filters with the same number of groups to process the sampled voltage signal, and output harmonic signals of different harmonic groups; S3, performing harmonic conversion through a V / F conversion circuit corresponding to a plurality of groups of tunable bandpass filters, and outputting frequency values of different harmonic groups; S4. The MCU controller calculates the amplitude of each harmonic according to the obtained frequency values of different harmonic groups.

7. The method for improving sampling accuracy based on amplitude and frequency dimension conversion according to claim 6, characterized in that: The frequency value of step S3 is: Among them, F out is the frequency value, V int is the initial amplitude of the voltage / current analog sampling signal collected by the front-end acquisition circuit, K1 is the full-scale value of the input voltage of the V / F conversion circuit, and F clock is the reference frequency value.

8. The method for improving sampling accuracy based on amplitude and frequency dimension conversion according to claim 6, characterized in that: The amplitude of each harmonic in step S3 is: Among them, V n is the amplitude of each harmonic, K1 is the full-scale value of the input voltage of the V / F conversion circuit, K2 is the calibration coefficient, F out is the frequency value of different harmonic groups, that is, the frequency value of each harmonic, F clock is the reference frequency value.

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