CN106054110A - Intelligent electric energy meter harmonic influence testing method - Google Patents

Abstract

The invention discloses an intelligent electric energy meter harmonic influence testing method. A testing system is composed of a computer, a general control center, a meter position function testing module, a programmable power supply, a standard electric energy meter, a harmonic generator, a carrier box, and an even harmonic matching device. The testing system automatically switches testing wires for a basic error test and DC and even harmonic tests. The programmable power supply is adopted to provide testing current I1 and voltage U1 of a tested meter and testing current I2 and voltage U2 needed by the standard electric energy meter. The current harmonic generator is equipped for realizing harmonic output needed by electric energy detection. The carrier box is equipped for realizing carrier communication by the device. The DC even harmonic matching device is adopted to automatically match current two ends of a load to meet testing conditions of the DC even harmonic test. The method of the invention has the advantages of simplicity, accurate testing result and strong operability.

Description

A test method for harmonic influence of smart electric energy meter

technical field

The invention relates to a method for testing the harmonic influence of an intelligent electric energy meter.

Background technique

Industrial production equipment with high-power power electronic devices are widely used in the field. Because the power electronic devices directly change the waveform of the current, the harmonic current component exceeds the standard, and the harmonic current generated by the load end passes through the internal resistance of the wire and the internal resistance of the transformer. Resistance, resulting in harmonic voltage, resulting in distortion of the original sinusoidal voltage waveform. This kind of harmonic source load not only affects the operation safety of the power grid, but also generates corresponding active power loss due to the existence of harmonic current and harmonic voltage, which affects the accuracy of electric energy measurement of the power grid. This influence is mainly reflected in the fact that the main theoretical basis of the current electric energy meter, the power triangle equation (active square + reactive square = apparent square), is no longer valid in the case of harmonics. In terms of metering, when the on-site load injects harmonics into the grid, the harmonic voltage and harmonic current will generate active energy, which will be offset to the fundamental active energy, resulting in undercounting of the full wave energy. When the grid power supply itself has harmonics, the generated harmonic active energy will be superimposed on the fundamental active energy, resulting in overcounting of the full wave energy. More and more attention has been paid to the characteristics of smart energy meters affected by harmonics.

Contents of the invention

In order to solve the above problems, the present invention provides a test method capable of testing the degree of influence of harmonics on smart electric energy meters.

Technical scheme of the present invention:

A method for testing the influence of harmonics on an intelligent electric energy meter. The test system is composed of a computer, a master control center, a meter function test module, a program-controlled power supply, a standard electric energy meter, a harmonic generator, a carrier box, and an even-order harmonic matching device. The above test system automatically converts the test wiring of the basic error test, DC and even harmonic test; the program-controlled power supply is used to provide the test current I1 and voltage U1 of the meter under test and the test current I2 and voltage U2 required by the standard electric energy meter, equipped with current The harmonic generator realizes the harmonic output required for electric energy detection, and is equipped with a carrier box to realize the carrier communication of the device, and adopts a DC even-order harmonic matching device to automatically match the current at both ends of the load to meet the test conditions of the DC even-order harmonic test.

Beneficial effects of the present invention:

The method is simple, the test result is accurate, and the operability is strong.

Description of drawings

Fig. 1 system structure block diagram;

Figure 2 is a schematic diagram of generating electric energy harmonics;

Fig. 3 produces the waveform diagram of direct current even order harmonic;

Figure 4 shows the waveform diagram of subharmonic generation;

Figure 5 shows the waveform of odd harmonics;

Figure 6. Measured diagram of DC even harmonics;

Figure 7: Harmonic measured graph;

Figure 8 Odd harmonic measured graph;

Figure 9 The actual measurement diagram of the odd harmonic rising edge.

detailed description

As shown in Figure 1, a test method for the influence of harmonics on a smart electric energy meter, the test system consists of a computer, a master control center, a meter function test module, a program-controlled power supply, a standard electric energy meter, a harmonic generator, a carrier box, an even harmonic The test system is composed of a wave matching device, and the test system automatically converts the test wiring of the basic error test, DC and even-order harmonic test; the program-controlled power supply is used to provide the test current I1 and voltage U1 of the meter under test and the test current I2 required by the standard electric energy meter , Voltage U2, equipped with a current harmonic generator to realize the harmonic output required for electric energy detection, equipped with a carrier box to realize the carrier communication of the device, and adopting a DC even-order harmonic matching device to automatically match the current at both ends of the load to meet the DC even-order harmonic test Test Conditions.

Under the control of the computer, the standard electric energy meter sends the power standard electric energy pulse to the meter function test module, and the meter function test module simultaneously collects the meter pulse and calculates the error. The industrial CAN bus is uploaded to the master control center. The master control center monitors, manages and uploads the data to the computer for processing on the surface data monitoring interface; the master control center mainly completes button processing, computer data processing, multi-function meter 485 communication, standard meter data processing (voltage, current, power, Phase, frequency, etc.), surface error data collection, voltage and current output control, temperature and humidity data collection, power consumption data collection, various functional test control, etc.; at the same time, the collected data is sent to the computer for comprehensive management.

As shown in Figure 2, the harmonic influence test is divided into four tests: high-order harmonics of voltage and current loops, direct current and even-order harmonics of current loops, odd-order harmonics, and sub-harmonics. The high-order harmonics of the voltage and current circuit are generated by the program-controlled power supply. The computer sends the required harmonic order, harmonic content, harmonic phase and other parameters to the program-controlled power supply. The program-controlled power supply calculates the full-wave waveform and outputs it to the detected Meter and standard meter, the error calculator compares the pulse of the standard meter with the pulse of the tested meter to calculate the error of the tested meter under such harmonics. Under the control of the computer, the program-controlled power supply can generate a variety of high-order harmonic combinations for error verification, and can also be compared with pure fundamental wave errors to calculate the impact of high-order harmonic errors.

During the test, the harmonic generation control circuit receives computer control instructions, controls the closing and opening of K1, K2, and K3, and controls the electronic switch to be turned on and off according to the set sequence. The automatic matching control circuit changes the resistance value of the variable resistor according to the current on the current sampling resistor to adjust the currents of the two loops to be equal. During the non-harmonic test, K1 is closed, K2 and K3 are disconnected, and the full-wave current of the program-controlled power supply passes through the tested meter and the standard meter. This connection method is exactly the same as the conventional calibration table. This method requires that the trigger signal to control the electronic switch is synchronized with the current source, and the control point is accurate.

As shown in Figure 3 and Figure 6, during the DC and even-order harmonic tests, there is a large error when the standard meter current detection circuit is directly connected to the even-order harmonic current, so the standard meter is connected to the full-wave current. K2 is closed, K1 and K3 are disconnected. Under the control of electronic switch 1 and electronic switch 2, the positive half cycle of the current source current flows through the electric energy meter under test, and the negative half cycle flows through the matching resistance circuit. A standard energy meter returns current to a current source. Due to the transient response problem of the program-controlled current source, when the resistance of the tested meter loop and the matching loop are unbalanced, the currents of the checked meter loop and the matching loop will be unequal, causing system errors. Here, an automatic matching circuit (DC even harmonic Automatic matching instrument), the current sampling resistors are set on the two circuit loops inside the even-time matching box, and the variable resistors are set on the matching loops. The automatic matching control circuit adjusts the variable resistors according to the current on the two sampling resistors to make the two currents equal, thereby eliminating systematic errors caused by matching. The error calculator sets the constant of the tested meter to 1/2 of the nominal value during the even-order harmonic calibration, and calculates the value of the tested meter under DC even-order harmonics by comparing the pulse of the standard meter with the pulse of the tested meter. Error, this error is compared with the full-wave error under the same current to obtain the influence of DC even-order harmonic error. The waveform diagram of DC even-order harmonics is shown in Figure 3. In the waveform diagram, the abscissa represents the period (ms), and the ordinate represents the magnification of the waveform (the same below).

As shown in Figure 4 and Figure 7, during the sub-harmonic test, the current detection circuit of the standard meter is also connected to the sub-harmonic current. At this time, K3 is closed, K1 and K2 are disconnected, and under the control of electronic switch 1 and electronic switch 2 Next, the first two cycles of every four cycles of current flow through the matching circuit, and the last two cycles flow through the tested meter and the standard meter circuit. The error calculator calculates the error of the inspected meter under the sub-harmonic by comparing the pulse of the standard meter with the pulse of the inspected meter, and compares this error with the full-wave error under the same current to obtain the influence of the sub-harmonic error. The waveform diagram generated by the sub-harmonic is shown in Figure 4.

As shown in Figure 5, Figure 8 and Figure 9, during the odd harmonic test, the current detection circuit of the standard meter is also connected to the odd harmonic current. At this time, K3 is closed, K1 and K2 are disconnected, and the electronic switch 1 and Under the control of electronic switch 2, the first 1/4 cycle and the third 1/4 cycle of each cycle flow through the matching circuit, and the second 1/4 cycle and the fourth 1/4 cycle flow through the tested meter and Standard meter loop. The error calculator calculates the error of the inspected meter under odd harmonics by comparing the pulse of the standard meter with the pulse of the inspected meter, and compares this error with the full-wave error under the same current to obtain the influence of the odd harmonic error.

As shown in Table 1, during the test, the voltage waveform distortion of the system device is 0.3%, the current waveform distortion is 0.2%, the power stability is 0.04%/120s, the frequency output range is 45Hz-65Hz, and the voltage output adjustment range 0-120%, the current output adjustment range is 0-120%, and the frequency adjustment fineness is 0.01Hz.

The test system can not only perform routine tests, but also realize the power consumption measurement of voltage loop, current loop power consumption test, harmonic influence test, event active reporting test, communication module interchangeability test, communication module interface load capacity test, etc. The test of the newly added project, in which the following data are obtained through the harmonic test:

In the range of 0-50Hz, 50-100KHz, and 100-150 KHz, the content of DC harmonics is 83%, 60%, and 8% respectively; in the range of 37.5HZ, 62.5Hz, the content of sub-harmonics is 81.3%. , 59.0%, when the odd harmonic times are 3rd, 5th, 7th, 9th, 11th, 13th, and 15th, the harmonic content is 54.2%, 19.5%, 17.3%, 13.2% %, 11.1%, 8.1%, 8.2%. It meets the requirements of the national standard GB/T17215.321-2008 (12-level static active energy meter) for current DC even-order harmonics, sub-harmonics, and odd-order harmonic waveforms.

Table 1 Harmonic experiment results

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (1)

1. an intelligent electric energy meter harmonic effects method of testing, it is characterised in that: test system is by computer, overall control center, table Bit function tentative module, programmable power supply, standard electric energy meter, harmonic oscillator, carrier wave case, even-order harmonic coalignment form, institute State test system and automatically change elementary error test, direct current and the test connection of even-order harmonic test；Employing programmable power supply provides Test current I2, voltage U2 needed for test current I1, voltage U1 and the standard electric energy meter taken temperature, is equipped with current harmonics and occurs Device realizes the harmonic wave that electric energy detection needs, and is equipped with carrier wave case and realizes the carrier communication of device, uses direct current even-order harmonic The equipped electric current at Auto-matching load two ends of putting is to meet direct current even-order harmonic experimental test condition.