Voltage ripple control method for electric energy meter and electric energy meter

Abstract

The invention provides a voltage ripple control method for an electric energy meter and the electric energy meter, and relates to the technical field of electric power metering and load control, and the method comprises the following steps: carrying out the sampling of a power grid voltage through an analog-to-digital converter, and obtaining a voltage digital signal containing a ripple signal; performing digital filtering processing on the voltage digital signal, and extracting a ripple signal in a specific frequency range; performing signal feature calculation on the extracted ripple signal, and converting the ripple signal into a digital level signal sequence; analyzing the digital level signal sequence according to a preset ripple control protocol, and identifying a control command; and executing a corresponding control action according to the identified control command. According to the invention, the receiving and decoding functions of the ripple control signal are integrated in the electric energy meter microprocessor, so that the system deployment and maintenance cost is reduced; flexible switching of multiple frequency points is supported; and the maintainability of the system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric power metering and load control, and particularly relates to a voltage ripple control method for an electric energy meter and the electric energy meter. BACKGROUND

[0002] Power companies widely use ripple control systems for load management in power transmission and distribution services. A high-frequency, low-power control signal, i.e., a ripple signal, is superimposed on the normal alternating voltage to control the operation of loads such as street lamps and water heaters or to execute other instructions in a large area. The sending end modulates the control command into a ripple signal of a specific frequency and injects it into the power line, and the receiving end needs to separate the signal of the frequency from the voltage data and parse the control command.

[0003] In the traditional scheme, a dedicated ripple receiver needs to be deployed as a control node in response to the ripple control function. The ripple receiver exists independently of the electric energy meter and is equipped with a special signal processing circuit and a microprocessor for filtering, demodulation and analysis of the ripple signal. This architecture has obvious problems: first, the dedicated hardware increases the system deployment cost, and each control point needs to install additional ripple receiving equipment; second, the maintenance cost of the independent device is high, and fault diagnosis and replacement need to be handled separately; third, the ripple receiver and the smart electric energy meter need to interact through an interface, increasing the system complexity.

[0004] In recent years, the electric energy meter has perfect microprocessor and communication capabilities, but it still acts as a passive device in the ripple control application and fails to fully utilize its computing and communication resources. The existing electric energy meter has configured an AD converter for voltage and current sampling, and the microprocessor has digital signal processing capability, which can theoretically be used for ripple signal extraction and analysis, but there is no mature technical solution to realize this integration.

[0005] The existing ripple receiving technology mainly uses analog filters or simple digital comparators for signal processing. Although the analog filter has fast response speed, it is easily affected by temperature and component aging, and is difficult to adjust after the parameters are fixed, and lacks flexibility in application scenarios that require switching multiple frequency points. The simple voltage comparison or pulse counting method has limited fault tolerance when the signal is weak or there is interference, and fails to fully utilize the advantages of modern digital signal processing technology.

[0006] In addition, the configuration parameters of the traditional ripple receiver are fixed in the hardware or firmware, and on-site adjustment requires manual operation, which cannot adapt to changes in the power grid environment or remote management needs. With the development of smart grids, power companies hope to remotely and flexibly adjust the frequency, protocol type and trigger threshold of the ripple control, but the configurability of the existing scheme is limited by the hardware architecture.

[0007] The Chinese patent document CN107493119B discloses a DC bus carrier communication system based on VPPM using power supply ripple, discloses a technical solution of driving a converter circuit switch tube by a VPPM modulation mode, and loading data to a DC bus ripple signal, which has the technical effects of saving a dedicated modulation line and reducing communication cost, but the solution focuses on signal modulation technology of the sending end, is mainly applied to DC bus carrier communication, and the signal processing method at the receiving end is relatively simple, only a voltage comparator or a hysteresis comparator is used for demodulation, and the filtering precision and anti-interference capability are limited, and the deep integration with the smart electric energy meter and the remote configuration capability are not involved.

[0008] The European patent document EP1555534A1 discloses an electronic electric energy meter with ripple control receiver, discloses a technical solution of implementing a digital filter in a microprocessor of the electric energy meter, and receiving a ripple signal by using an output of a voltage AD converter, which has the technical effects of not needing independent ripple receiver hardware and reducing system cost, but the solution does not make detailed description on the design method and parameter configuration of the digital filter, only mentions frequency-pulse conversion and telegraph template comparison, lacks description on specific filtering algorithm, multi-frequency point support, protocol analysis details and remote configuration function, and the operability of engineering implementation and system flexibility are still insufficient. SUMMARY

[0009] The purpose of the present application is to provide a voltage ripple control method for an electric energy meter, which does not need a dedicated ripple receiver, has low cost, stable and reliable signal processing, and supports remote configuration.

[0010] To achieve the above purpose, the present application realizes the following technical solution: A voltage ripple control method for an electric energy meter, applied to an electric energy meter including an analog-to-digital converter and a microprocessor, includes the following steps: S1: sampling grid voltage to obtain a voltage digital signal containing a ripple signal; S2: performing digital filtering processing on the voltage digital signal to extract a ripple signal in a specific frequency range; S3: performing signal feature calculation on the extracted ripple signal to convert the ripple signal into a digital level signal sequence; S4: analyzing the digital level signal sequence according to a preset ripple control protocol to output a control instruction.

[0011] Further, the S2 includes: S21: filtering the voltage digital signal by a band-pass filter, and the passband frequency range of the band-pass filter is 100Hz to 1500Hz; S22: adjusting the amplitude of the filtered signal according to a preset proportional coefficient.

[0012] Further, the band-pass filter is an IIR band-pass filter, and the voltage digital signal is filtered by a cascade manner.

[0013] Further, the signal feature calculation on the extracted ripple signal in S3 comprises: S31: calculating the root mean square value of the extracted ripple signal in a preset time window; S32: comparing the root mean square value with a preset threshold, determining high level when the root mean square value is higher than the preset threshold, and determining low level when the root mean square value is lower than or equal to the preset threshold; S33: repeating the above calculation and comparison according to a sampling period of 10ms to 50ms to generate a digital level signal sequence.

[0014] Further, the preset threshold is 0.5% to 5% of the effective value of voltage.

[0015] Further, the digital level signal sequence is parsed according to a preset ripple control protocol in S4, comprising: S41: detecting a start identification signal in the digital level signal sequence; S42: identifying a data segment subsequent to the start identification signal; S43: converting the level duration in the data segment into a bit value according to a preset protocol rule; S44: combining the bit value into a control command.

[0016] Further, the preset protocol rule supports at least one of Decabit protocol and Telenerg protocol, and different protocols define the correspondence between level duration and bit value through corresponding preset time parameters.

[0017] Further, before S1 is executed, further comprising: receiving a remote configuration instruction, and adjusting the filtering frequency of digital filtering processing, the threshold value of signal feature calculation, or the protocol type of protocol parsing according to the remote configuration instruction.

[0018] An electric energy meter for implementing the above method, comprising an analog-to-digital converter and a microprocessor, wherein the microprocessor comprises: a digital filtering module, an input end of the digital filtering module being connected to an output end of the analog-to-digital converter, for performing digital filtering processing on the voltage digital signal to extract a ripple signal in a specific frequency range; a signal determination module, an input end of the signal determination module being connected to an output end of the digital filtering module, for performing signal feature calculation on the extracted ripple signal and converting the ripple signal into a digital level signal sequence. a protocol analysis module, an input end of the protocol analysis module being connected to an output end of the signal determination module, and configured to parse the digital level signal sequence according to a preset ripple control protocol and output a control instruction; a control execution module, an input end of the control execution module being connected to an output end of the protocol analysis module, and configured to receive the control instruction and control a load switch state.

[0019] Further, the microprocessor further comprises: a configuration management module, the configuration management module being connected to a remote communication interface, and configured to receive a remote configuration instruction and adjust a filter parameter of the digital filter module, a threshold value of the signal determination module or a protocol type of the protocol analysis module; an energy calculation module, an input end of the energy calculation module being connected to an output end of the analog-to-digital converter, and configured to calculate an electric energy consumption amount according to sampling data of the analog-to-digital converter.

[0020] Compared with the prior art, the present application has the following beneficial effects: Firstly, the present application integrates the receiving and decoding function of the ripple control signal in the microprocessor of the electric energy meter, and uses the analog-to-digital converter and the microprocessor resource of the electric energy meter to complete the extraction and analysis of the ripple signal, so that the subsequent load operation is directly controlled by the electric energy meter. Compared with the traditional scheme which needs to additionally deploy an independent ripple receiver hardware, the present application does not need to increase special equipment, thereby saving the hardware procurement cost, installation and deployment cost and later maintenance cost.

[0021] Secondly, the present application uses the IIR band-pass filter based on the CMSIS-DSP library for digital filtering, and supports the signal extraction of multiple frequency points in the wide frequency range of 175Hz to 1500Hz. The digital filter is not affected by temperature and component aging, and has high stability. The filter parameter can be adjusted through software programming, and different frequency points can be flexibly supported. Compared with the limitation of the fixed parameter of the traditional analog filter, the adaptability is stronger.

[0022] Thirdly, the present application uses the remote communication function of the electric energy meter, and can remotely adjust all key parameters of the ripple receiving, including the filter frequency, the judgment threshold and the protocol type, without the need of on-site manual operation. When the power grid environment changes or the ripple control protocol needs to be replaced, the configuration update can be completed through the remote instruction, thereby greatly reducing the on-site maintenance workload and improving the flexibility and maintainability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A flow chart of a voltage ripple control method for an electric energy meter is provided for the present application; Figure 2 A structural schematic diagram of an electric energy meter applying the voltage ripple control method is provided for the present application; Figure 3 This invention provides a schematic diagram of the working process of a voltage ripple control method for an electricity meter. Figure 4 This is a schematic diagram of the data frame structure in one embodiment of the present invention; Figure 5 This is a schematic diagram of the Decabit protocol in one embodiment of the present invention; Figure 6 This is a schematic diagram of the Telenerg protocol in one embodiment of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 like Figure 1 and Figure 3 As shown, this invention provides a voltage ripple control method for electricity meters, applied to electricity meters including analog-to-digital converters and microprocessors, comprising the following steps: S1: Sample the grid voltage to obtain a digital voltage signal containing ripple signals; S2: Perform digital filtering on the voltage digital signal to extract the ripple signal within a specific frequency range; S3: Perform signal feature calculation on the extracted ripple signal and convert the ripple signal into a digital level signal sequence; S4: Parse the digital level signal sequence according to the preset ripple control protocol and output control commands. Specifically, such as... Figure 4 As shown, the energy meter uses an HCT5821B chip to convert the input voltage signal into a discrete signal via an ADC. It reads the ADC data output through an SPI interface, processes the read data according to the data frame structure, and repeats the reading process to obtain continuous discrete signal values. The discrete voltage signal is then input to a microprocessor for further processing, completing the entire process from signal acquisition to control execution. Figure 4Specifically, the frame structure of the ADC data output is represented, the first byte is all 0, indicating the start, the next three bytes are the value of ADCA, of which the first two bytes are data and the last byte is 0, and the next three bytes are the value of ADCB, of which the first two bytes are data and the last byte is 0, ADCA and ADCB correspond to voltage and current data respectively, and the last byte is the checksum, which is the sum of ADCA and ADCB and the value of 0x5A. By integrating the reception and decoding function of the ripple control signal, the subsequent load is directly controlled by the electric energy meter, without deploying a dedicated ripple receiver, reducing the deployment cost and maintenance cost.

[0026] In one specific embodiment of the present embodiment, the digital filtering of the voltage digital signal includes filtering the voltage digital signal through a band-pass filter, and the passband frequency range of the band-pass filter is 100Hz to 1500Hz; and the amplitude of the filtered signal is adjusted by a preset proportion coefficient. The frequency range of the ripple signal injected by the power company is usually 100Hz to 1400Hz, and the band-pass filter is set to a passband range of 100Hz to 1500Hz, which can cover all commonly used ripple frequencies. The filtered signal needs to be scaled by a specific proportion coefficient, which is calculated together when calculating the filter parameters. The band-pass filtering separates the ripple signal of a specific frequency from the voltage signal containing the fundamental wave and each harmonic, providing an accurate ripple waveform for subsequent signal determination.

[0027] In one specific embodiment of the present embodiment, the band-pass filter is an IIR band-pass filter, which filters the voltage digital signal in a cascading manner. The IIR band-pass filter is realized based on the CMSIS-DSP library, and the required filter parameters are calculated by the fdatool tool in matlab, thereby obtaining a filter for a specific ripple frequency. Cascaded filtering refers to the use of multiple filters in series to gradually improve the filtering effect. Compared with an analog filter, an IIR filter is not affected by temperature and component aging, and the parameters can be programmed and adjusted to flexibly support multiple frequency switching requirements. Currently, it supports signal filtering for multiple frequencies between 175Hz and 1500Hz.

[0028] In one specific embodiment of this example, the signal feature calculation of the extracted ripple signal includes: calculating the root mean square (RMS) value of the extracted ripple signal within a preset time window; comparing the RMS value with a preset threshold, determining a high level when the RMS value is higher than the preset threshold, and a low level when the RMS value is lower than or equal to the preset threshold; repeating the above calculation and comparison at a sampling period of 10ms to 50ms to generate a digital level signal sequence. The filtered ripple signal is still a series of discrete data, and its RMS value needs to be calculated to obtain the effective value of the ripple signal. The effective value is compared with a set judgment threshold; if it is higher than the threshold, it is determined to be a high level; otherwise, it is a low level. One signal point is acquired in each sampling period, and continuous sampling forms a high-low level sequence. In a specific implementation, the sampling period is set to 20ms, that is, one signal point is acquired every 20ms. Through RMS value calculation and threshold comparison, the analog ripple signal is converted into a high-low level sequence that is easy to digitally process.

[0029] In one specific embodiment of this example, the preset threshold is 0.5% to 5% of the effective voltage value. The amplitude of the ripple signal is typically 1% to 5% of the grid voltage. Setting the judgment threshold to 1% of the effective voltage value can effectively identify the presence of the ripple signal. A threshold value that is too low will lead to false triggering, while a threshold value that is too high will lead to missed detection. The range of 0.5% to 5% can accommodate the ripple signal intensity under different grid environments.

[0030] In one specific embodiment of this example, parsing a digital level signal sequence according to a preset ripple control protocol includes: detecting a start identifier signal in the digital level signal sequence; identifying data segments following the start identifier signal; converting the level duration in the data segments into bit values ​​according to preset protocol rules; and combining the bit values ​​into a control command. The ripple control protocol represents control commands through specific high and low level combinations. The start identifier signal is used to mark the beginning of a command. After identifying the start identifier, subsequent data segments are parsed according to the timing rules specified in the protocol. Different durations of high and low levels correspond to different bit values; combining the parsed bit values ​​in sequence yields a complete control command. By repeatedly executing the above steps, continuous ripple high and low level signals can be obtained. Control commands are then parsed according to the protocol, and the energy meter performs corresponding actions based on the command content agreed upon in the protocol.

[0031] In one specific implementation of this embodiment, such as Figures 5-6As shown, the preset protocol rule supports at least one of Decabit protocol and Telenerg protocol, and different protocols define the correspondence between the level duration and the bit value through corresponding preset time parameters. In the Decabit protocol, 600 ms high level indicates the start of the control command, and the subsequent 600 ms signal is 1 bit, 600 ms high level is bit 1, and 600 ms low level is bit 0. A command is 10 bits long, and 600 ms low level indicates the end of the command. In the Telenerg protocol, 1650 ms high level and 600 ms low level indicate the start of the control command, and the subsequent 1000 ms signal is 1 bit, the first 400 ms is high level and the last 600 ms is low level, indicating bit 1, and 1000 ms low level indicates bit 0. By supporting multiple protocols, the watt-hour meter can adapt to the ripple control standards used by different power companies.

[0032] In one specific embodiment of the present embodiment, before step 1 is performed, it further includes receiving a remote configuration instruction, and adjusting the filter frequency of the digital filter processing, the threshold value of the signal feature calculation, or the protocol type of the protocol analysis according to the remote configuration instruction. The watt-hour meter itself supports remote communication, and can remotely adjust the ripple reception configuration as needed. The remote configuration content includes switching ripple control function, changing reception frequency, changing ripple protocol, adjusting signal strength threshold, etc. After receiving the remote configuration instruction, the microprocessor updates the corresponding parameter settings, and the subsequent ripple detection is performed according to the new configuration. The remote configuration function makes the watt-hour meter flexible to adapt to different application scenarios, and the parameter adjustment can be completed without on-site operation, improving the maintainability of the system.

[0033] Embodiment 2 As Figure 2 As shown, the present application provides a watt-hour meter for implementing the above method, which includes an analog-to-digital converter and a microprocessor. The microprocessor includes: a digital filter module, the input end of the digital filter module being connected to the voltage sampling output end of the analog-to-digital converter; a signal judgment module, the signal judgment module being connected to the output end of the digital filter module; a protocol analysis module, the protocol analysis module being connected to the output end of the signal judgment module; and a control execution module, the control execution module being connected to the output end of the protocol analysis module. The digital filter module implements a band-pass filter function to extract the ripple signal from the voltage sampling data. The signal judgment module calculates the root mean square value of the ripple signal and compares it with the threshold to generate a high-low level sequence. The protocol analysis module analyzes the high-low level sequence according to the preset protocol rule to identify the control command. The control execution module executes the corresponding action according to the control command, such as pulling the relay or closing the relay. By integrating the above functional modules in the microprocessor of the watt-hour meter, the integration of ripple control and electric energy metering is realized, and a dedicated ripple receiver does not need to be additionally deployed.

[0034] In one specific embodiment of the present embodiment, the microprocessor further comprises a configuration management module connected to the remote communication interface, configured to receive remote configuration instructions and adjust the filtering parameters of the digital filtering module, the threshold value of the signal determination module or the protocol type of the protocol analysis module; and an energy calculation module configured to calculate the power consumption according to the sampling data of the analog-to-digital converter. The configuration management module receives the configuration instructions through the remote communication interface, analyzes the instruction content and modifies the parameters of the corresponding module. The energy calculation module realizes the basic metering function of the electric energy meter, and calculates the power consumption according to the voltage and current sampling data. The configuration management module and the energy calculation module are integrated in the same microprocessor as the ripple control related modules, realizing the integration of metering and control functions, improving the equipment integration and resource utilization.

[0035] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent transformation or modification made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A method for voltage ripple control on an electric energy meter, characterized by: The method comprises the following steps: S1: sampling the grid voltage to obtain a voltage digital signal containing a ripple signal; S2: performing digital filtering processing on the voltage digital signal to extract a ripple signal in a specific frequency range; S3: performing signal feature calculation on the extracted ripple signal to convert the ripple signal into a digital level signal sequence; S4: parsing the digital level signal sequence according to a preset ripple control protocol to output a control instruction.

2. A method for voltage ripple control on an electric energy meter according to claim 1, characterized in that: The digital filtering processing on the voltage digital signal in S2 comprises: S21: filtering the voltage digital signal through a band-pass filter, wherein the passband frequency range of the band-pass filter is 100 Hz to 1500 Hz; S22: performing amplitude adjustment on the filtered signal according to a preset proportion coefficient.

3. A method for voltage ripple control on an electric energy meter according to claim 2, characterized in that: The band-pass filter is an IIR band-pass filter, and the voltage digital signal is filtered through a cascade mode.

4. A method for voltage ripple control on an electric energy meter according to claim 1, characterized in that: The signal feature calculation on the extracted ripple signal in S3 comprises: S31: calculating the root mean square value of the extracted ripple signal in a preset time window; S32: comparing the root mean square value with a preset threshold, and determining a high level when the root mean square value is higher than the preset threshold, and determining a low level when the root mean square value is lower than or equal to the preset threshold; S33: repeating the above calculation and comparison according to a sampling period of 10 ms to 50 ms to generate a digital level signal sequence.

5. A method for voltage ripple control on an electricity meter as claimed in claim 4, wherein: The preset threshold is 0.5% to 5% of the voltage effective value.

6. A method for voltage ripple control on an electric energy meter as claimed in claim 1, wherein: The parsing of the digital level signal sequence according to the preset ripple control protocol in S4 comprises: S41: detecting a start identification signal in the digital level signal sequence; S42: identifying a data segment subsequent to the start identification signal; S43: converting the level duration in the data segment into a bit value according to a preset protocol rule; S44: combining the bit value into a control command.

7. A method for voltage ripple control on an electricity meter as claimed in claim 6, characterized in that: The preset protocol rule supports at least one of a Decabit protocol and a Telenerg protocol, and different protocols define the correspondence between the level duration and the bit value through corresponding preset time parameters.

8. A method for voltage ripple control on an electric energy meter as claimed in claim 1, wherein: Before S1 is performed, the following step is further included: receiving a remote configuration instruction, and adjusting the filtering frequency of the digital filtering processing, the threshold value of the signal feature calculation, or the protocol type of the protocol parsing according to the remote configuration instruction.

9. An electric energy meter implementing the method of any one of claims 1 to 8, comprising an analog-to-digital converter and a microprocessor, characterized in that, The microprocessor comprises: a digital filtering module, an input end of the digital filtering module being connected to an output end of an analog-to-digital converter, for performing digital filtering processing on the voltage digital signal to extract a ripple signal in a specific frequency range; a signal determination module, an input end of the signal determination module being connected to an output end of the digital filtering module, for performing signal feature calculation on the extracted ripple signal and converting the ripple signal into a digital level signal sequence; a protocol parsing module, an input end of the protocol parsing module being connected to an output end of the signal determination module, for parsing the digital level signal sequence according to a preset ripple control protocol and outputting a control instruction; a control execution module, an input end of the control execution module being connected to an output end of the protocol parsing module, for receiving the control instruction and controlling the load switch state.

10. The electric energy meter of claim 9, wherein, The microprocessor further comprises: A configuration management module is connected with the remote communication interface, and is used for receiving remote configuration instructions and adjusting filter parameters of the digital filter module, threshold values of the signal determination module or protocol types of the protocol analysis module. An energy calculation module is connected with the output end of the analog-digital converter, and is used for calculating the electric energy consumption according to the sampling data of the analog-digital converter.

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