Direct-current electric energy meter self-calibration method and system

Abstract

The invention provides a direct-current electric energy meter self-calibration method and system. The method comprises the following steps: acquiring an internal high-precision low-temperature drift voltage reference signal; converting the voltage reference signal into an analog calibration voltage signal on a sampling resistor by controlling a direct current standard voltage generation circuit according to the voltage reference signal; converting the voltage reference signal into an analog calibration current signal in a current loop by controlling a DC voltage-current conversion circuit according to the voltage reference signal; obtaining a current environment temperature, and calculating a calibration gain at the current temperature according to a preset temperature coefficient; according to a theoretical calibration value, calculating a voltage gain, a current gain and a power gain of the sampling voltage value and the sampling current value, and writing the gains into a memory; and correcting the reference voltage signal according to the obtained temperature calibration gain, and performing temperature compensation.

Description

Technical Field

[0001] The invention belongs to the field of electric energy meters, and in particular relates to a self-calibration method and system for a direct current electric energy meter. Background Art

[0002] With the rapid development of the new energy vehicle industry, high-voltage DC fast charging has been widely installed around the world, and high-voltage and high-current DC energy meters have also been widely used. The calibration of high-voltage and high-current DC energy meters requires a meter body with a high voltage of up to 1500V and a current of 600A-800A. Such high voltage and high current pose great challenges to the production and calibration of energy meters. In addition to the need to provide a high-voltage and high-current platform, there are also requirements for the line diameter of the access product. Providing high voltage and high current to calibrate the DC energy meter has high requirements for equipment, safety, and site. In the actual operation process, the high current will cause the platform and line to heat up, which will also have a certain impact on the measurement accuracy of the meter body.

[0003] When the ambient temperature fluctuates, the characteristics of the electronic components inside the equipment will change, causing performance drift of key components such as voltage reference signals and sampling circuits. This drift will cause systematic errors in the measurement results, causing deviations between the energy metering value and the actual power consumption.

[0004] In addition, the traditional single-point calibration method is difficult to fully cover the error characteristics of the equipment under different temperature and load conditions, which limits the calibration effect. These problems make it impossible for the electric energy meter to maintain stable high-precision measurement performance over the entire temperature range, affecting the reliability and accuracy of the power system measurement. Summary of the invention

[0005] The purpose of the present invention is to address the above-mentioned problems and propose a self-calibration method and system for a DC electric energy meter to realize automatic calibration of the DC electric energy meter, improve the production and adjustment efficiency of the DC electric energy meter, realize self-calibration during operation, improve real-time measurement accuracy, and improve the measurement accuracy of the DC electric energy meter in high and low temperature environments through temperature compensation.

[0006] The technical solution of the present invention is:

[0007] The present invention provides a direct current electric energy meter self-calibration method, comprising:

[0008] S1, generating a reference voltage signal, wherein the reference voltage signal is a circuit-level small signal;

[0009] S2. According to the reference voltage signal, control the DC standard voltage generating circuit and the DC voltage current conversion circuit to convert the reference voltage signal into an analog calibration voltage signal on the sampling resistor and an analog calibration current signal in the current loop respectively;

[0010] S3, obtaining the current ambient temperature, calculating the calibration gain at the current temperature according to the preset temperature coefficient; correcting the reference voltage signal according to the obtained temperature calibration gain, and performing temperature compensation;

[0011] S4, synchronously loading the analog calibration voltage signal and the analog calibration current signal into a signal conditioning circuit to obtain a sampled voltage value and a sampled current value at a current calibration point;

[0012] S5. Calculate the voltage gain, current gain and power gain of the sampled voltage value and the sampled current value according to the theoretical calibration value, and write the gain into a memory;

[0013] S6. Change the loop network resistance in the DC standard voltage generating circuit and the DC voltage-current conversion circuit, simulate multiple calibration points in sequence, and repeat the above steps until the full range calibration is completed.

[0014] Furthermore, the controlling of a DC standard voltage generating circuit according to the reference voltage signal to convert the reference voltage signal into an analog calibration voltage signal on a sampling resistor includes:

[0015] According to the reference voltage signal, the DC standard voltage generating circuit is controlled to generate an analog calibration voltage signal proportional to the amplitude of the reference voltage signal on the sampling resistor.

[0016] Further, the converting of the reference voltage signal into an analog calibration current signal in a current loop by controlling a DC voltage-to-current conversion circuit according to the reference voltage signal comprises:

[0017] The DC voltage-to-current conversion circuit is controlled according to the reference voltage signal to generate an analog calibration current signal in the current loop that is proportional to the amplitude of the reference voltage signal.

[0018] Furthermore, the obtaining of the current ambient temperature and calculating the calibration gain at the current temperature according to a preset temperature coefficient includes:

[0019] Acquiring the current ambient temperature through a temperature sensor;

[0020] The calibration gain at the current temperature is calculated according to the current ambient temperature and a preset temperature coefficient.

[0021] Furthermore, the step of synchronously loading the analog calibration voltage signal and the analog calibration current signal to a signal conditioning circuit to obtain a sampled voltage value and a sampled current value at a current calibration point includes:

[0022] Loading the analog calibration voltage signal to a voltage sampling channel, and loading the analog calibration current signal to a current sampling channel;

[0023] The analog calibration voltage signal and the analog calibration current signal are collected through the voltage sampling channel and the current sampling channel respectively to obtain the sampled voltage value and the sampled current value.

[0024] Further, the calculating of the voltage gain, current gain and power gain of the sampled voltage value and the sampled current value according to the theoretical calibration value includes:

[0025] The voltage gain is calculated based on the theoretical calibration value and the sampled voltage value;

[0026] According to the theoretical calibration value and the sampled current value, the current gain is calculated;

[0027] The power gain is calculated based on the voltage gain and the current gain.

[0028] Furthermore, the loop network resistance in the DC standard voltage generating circuit and the DC voltage-current conversion circuit is changed to simulate multiple calibration points in sequence, including:

[0029] By changing the resistance value of the voltage divider resistor in the DC standard voltage generating circuit, multiple voltage calibration points are simulated in sequence;

[0030] By changing the resistance value of the sampling resistor in the DC voltage-to-current conversion circuit, multiple current calibration points are simulated in sequence.

[0031] A direct current electric energy meter self-calibration system, comprising:

[0032] A reference voltage generation module, used for generating a circuit-level small signal as a reference voltage signal;

[0033] A DC standard voltage generating circuit converts the reference voltage signal into an analog calibration voltage signal on a sampling resistor and synchronously loads it to a signal conditioning circuit;

[0034] A DC voltage-to-current conversion circuit converts the reference voltage signal into an analog calibration current signal in a current loop and synchronously loads the signal to a signal conditioning circuit;

[0035] MCU, controls the loop network resistance in the DC standard voltage generating circuit and the DC voltage-to-current conversion circuit, generates analog calibration voltage signals and analog calibration current signals, loads them into the signal conditioning circuit, simulates different calibration points, obtains the sampled voltage value and sampled current value at each calibration point, and calculates the voltage gain, current gain, and power gain;

[0036] The temperature compensation module is used to obtain the temperature calibration gain coefficient at each calibration point, correct the reference voltage, and complete temperature compensation.

[0037] Beneficial effects of the present invention:

[0038] The present invention adds a self-calibration system inside the DC energy meter to realize automatic calibration of the DC energy meter within the full voltage and current range during the production process, which can greatly improve the calibration efficiency of the DC energy meter, reduce the investment in production equipment, reduce safety risks, and improve the measurement accuracy of the DC energy meter.

[0039] The high-precision electric energy metering calibration method of the present invention aims at the problem of measurement error of electric energy metering equipment under different temperature environments. It obtains the internal high-precision low-temperature drift voltage reference signal, converts it into analog calibration voltage and current signals, and performs compensation calibration in combination with the ambient temperature factor.

[0040] The method of the present invention adopts a multi-point calibration strategy, simulates different calibration points by changing the resistance of the loop network, obtains the gain relationship between the sampled value and the theoretical value, and finally combines the temperature compensation factor with the gain calibration result to achieve high-precision calibration in the full range and full temperature.

[0041] The present invention solves the problem of measurement accuracy of traditional electric energy metering equipment in a temperature-changing environment, significantly improves the accuracy and reliability of electric energy metering, and provides technical guarantee for accurate metering of power systems.

[0042] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0044] Figure 1 The block diagram of the self-calibration system of a DC electric energy meter of the present invention is shown. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0046] Example 1

[0047] The present invention provides a direct current electric energy meter self-calibration method, comprising:

[0048] S1, generating a reference voltage signal, wherein the reference voltage signal is a circuit-level small signal;

[0049] S2. According to the reference voltage signal, control the DC standard voltage generating circuit and the DC voltage current conversion circuit to convert the reference voltage signal into an analog calibration voltage signal on the sampling resistor and an analog calibration current signal in the current loop respectively;

[0050] S3. Obtain the current ambient temperature and calculate the calibration gain at the current temperature according to the preset temperature coefficient; obtain the current ambient temperature value through the temperature sensor and convert the temperature value into a digital signal. According to the obtained digital signal temperature value, query the preset temperature-temperature coefficient comparison table to obtain the calibration gain KT corresponding to the current temperature; according to the obtained temperature calibration gain, correct the reference voltage signal and perform temperature compensation;

[0051] S4, synchronously loading the analog calibration voltage signal and the analog calibration current signal into a signal conditioning circuit to obtain a sampled voltage value and a sampled current value at a current calibration point;

[0052] S5. Calculate the voltage gain, current gain and power gain of the sampled voltage value and the sampled current value according to the theoretical calibration value, and write the gain into a memory;

[0053] S6. Change the loop network resistance in the DC standard voltage generating circuit and the DC voltage-current conversion circuit, simulate multiple calibration points in sequence, and repeat the above steps until the full range calibration is completed.

[0054] Furthermore, the loop network resistance in the DC standard voltage generating circuit and the DC voltage-current conversion circuit is changed to simulate multiple calibration points in sequence, including simulating multiple voltage calibration points in sequence by changing the voltage divider resistance in the DC standard voltage generating circuit; and simulating multiple current calibration points in sequence by changing the sampling resistance in the DC voltage-current conversion circuit.

[0055] In this embodiment, a low-temperature drift and high-precision reference voltage signal is generated by controlling the reference voltage generation module. The signal is a small circuit-level signal. The DC standard voltage generation circuit is controlled to convert the calibration precision signal Un into a calibration signal on the sampling resistor. The DC voltage-current conversion circuit is controlled to realize the precision signal In of the current loop. The voltage and current signals are synchronously loaded into the conditioning circuit to realize the use of the internal circuit to generate the calibration signal.

[0056] Example 2

[0057] Figure 1 The block diagram of the self-calibration system of a DC electric energy meter of the present invention is shown.

[0058] A direct current electric energy meter self-calibration system, comprising:

[0059] A reference voltage generation module, used for generating a circuit-level small signal as a reference voltage signal;

[0060] A DC standard voltage generating circuit converts the reference voltage signal into an analog calibration voltage signal on a sampling resistor and synchronously loads it to a signal conditioning circuit;

[0061] A DC voltage-to-current conversion circuit converts the reference voltage signal into an analog calibration current signal in a current loop and synchronously loads the signal to a signal conditioning circuit;

[0062] MCU, controls the loop network resistance in the DC standard voltage generating circuit and the DC voltage-to-current conversion circuit, generates analog calibration voltage signals and analog calibration current signals, loads them into the signal conditioning circuit, simulates different calibration points, obtains the sampled voltage value and sampled current value at each calibration point, and calculates the voltage gain, current gain, and power gain;

[0063] The temperature compensation module is used to obtain the temperature calibration gain coefficient at each calibration point, correct the reference voltage, and complete temperature compensation.

[0064] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A self-calibration method for a DC electric energy meter, characterized in that: include: S1, generating a reference voltage signal, wherein the reference voltage signal is a circuit-level small signal; S2. According to the reference voltage signal, control the DC standard voltage generating circuit and the DC voltage current conversion circuit to convert the reference voltage signal into an analog calibration voltage signal on the sampling resistor and an analog calibration current signal in the current loop respectively; S3, obtaining the current ambient temperature, calculating the calibration gain at the current temperature according to the preset temperature coefficient; correcting the reference voltage signal according to the obtained temperature calibration gain, and performing temperature compensation; S4, synchronously loading the analog calibration voltage signal and the analog calibration current signal into a signal conditioning circuit to obtain a sampled voltage value and a sampled current value at a current calibration point; S5. Calculate the voltage gain, current gain and power gain of the sampled voltage value and the sampled current value according to the theoretical calibration value, and write the gain into a memory; S6. Change the loop network resistance in the DC standard voltage generating circuit and the DC voltage-current conversion circuit, simulate multiple calibration points in sequence, and repeat the above steps until the full range calibration is completed.

2. The self-calibration method for a DC electric energy meter according to claim 1, characterized in that: The method of controlling a DC standard voltage generating circuit according to the reference voltage signal to convert the reference voltage signal into an analog calibration voltage signal on a sampling resistor comprises: According to the reference voltage signal, the DC standard voltage generating circuit is controlled to generate an analog calibration voltage signal proportional to the amplitude of the reference voltage signal on the sampling resistor.

3. The self-calibration method for a DC electric energy meter according to claim 1, characterized in that: The method of converting the reference voltage signal into an analog calibration current signal in a current loop by controlling a DC voltage-to-current conversion circuit according to the reference voltage signal comprises: The DC voltage-to-current conversion circuit is controlled according to the reference voltage signal to generate an analog calibration current signal in the current loop that is proportional to the amplitude of the reference voltage signal.

4. The self-calibration method for a DC electric energy meter according to claim 1, characterized in that: The obtaining of the current ambient temperature and calculating the calibration gain at the current temperature according to a preset temperature coefficient include: Acquiring the current ambient temperature through a temperature sensor; The calibration gain at the current temperature is calculated according to the current ambient temperature and a preset temperature coefficient.

5. The self-calibration method for a DC electric energy meter according to claim 1, characterized in that: The step of synchronously loading the analog calibration voltage signal and the analog calibration current signal to a signal conditioning circuit to obtain a sampled voltage value and a sampled current value at a current calibration point includes: Loading the analog calibration voltage signal to a voltage sampling channel, and loading the analog calibration current signal to a current sampling channel; The analog calibration voltage signal and the analog calibration current signal are collected through the voltage sampling channel and the current sampling channel respectively to obtain the sampled voltage value and the sampled current value.

6. The self-calibration method for a DC electric energy meter according to claim 1, characterized in that: The step of calculating the voltage gain, current gain and power gain of the sampled voltage value and the sampled current value according to the theoretical calibration value comprises: The voltage gain is calculated based on the theoretical calibration value and the sampled voltage value; According to the theoretical calibration value and the sampled current value, the current gain is calculated; The power gain is calculated based on the voltage gain and the current gain.

7. The self-calibration method for a DC electric energy meter according to claim 1, characterized in that: The loop network resistance in the DC standard voltage generating circuit and the DC voltage-current conversion circuit is changed to simulate multiple calibration points in sequence, including: By changing the resistance value of the voltage divider resistor in the DC standard voltage generating circuit, multiple voltage calibration points are simulated in sequence; By changing the resistance value of the sampling resistor in the DC voltage-to-current conversion circuit, multiple current calibration points are simulated in sequence.

8. A DC electric energy meter self-calibration system, characterized in that: include: A reference voltage generation module, used for generating a circuit-level small signal as a reference voltage signal; A DC standard voltage generating circuit converts the reference voltage signal into an analog calibration voltage signal on a sampling resistor and synchronously loads it to a signal conditioning circuit; A DC voltage-to-current conversion circuit converts the reference voltage signal into an analog calibration current signal in a current loop and synchronously loads the signal to a signal conditioning circuit; MCU, controls the loop network resistance in the DC standard voltage generating circuit and the DC voltage-to-current conversion circuit, generates analog calibration voltage signals and analog calibration current signals, loads them into the signal conditioning circuit, simulates different calibration points, obtains the sampled voltage value and sampled current value at each calibration point, and calculates the voltage gain, current gain, and power gain; The temperature compensation module is used to obtain the temperature calibration gain coefficient at each calibration point, correct the reference voltage, and complete temperature compensation.

Images