CN105911318B - A kind of method of electric energy meter calibrating apparatus output harmonic wave, subharmonic and m-Acetyl chlorophosphonazo - Google Patents

Abstract

A method for outputting harmonics, sub-harmonics and simple harmonics of an electric energy meter verification device, including using a first signal source that can output power frequency waveforms and can superimpose power frequency integer multiple harmonics of the electric energy meter verification device. A second signal source that generates only sub-harmonics and inter-harmonics is also added. In the method, the output of the first signal source and the output of the second signal source are superimposed and synthesized through an adder built by an operational amplifier; that is, the power frequency signal of the first signal source, the power frequency integer multiple harmonic signal and the second The sub-harmonic signal and inter-harmonic signal output by the signal source are superimposed and synthesized into a waveform signal; then the synthesized signal is output to the power amplifier for amplification and output. The invention solves the problem that it is difficult to superimpose arbitrary harmonics on a set of signal sources in the traditional method, and is suitable for electric energy meter verification devices that not only output power frequency signals and power frequency integer multiple harmonic signals, but also superimpose or output subharmonics and Inter-harmonics, used to study and analyze the influence of harmonics on electric energy metering.

Description

A method for outputting harmonics, sub-harmonics and inter-harmonics of an electric energy meter verification device

technical field

The invention relates to a method for outputting harmonics, sub-harmonics and simple harmonics by a verification device of an electric energy meter, which belongs to the technical field of measuring and testing equipment.

Background technique

At present, with the rapid development of electronic technology, a large number of non-linear electrical equipment such as electric arc steelmaking furnace, impact load, power electronic frequency modulation, electric locomotive traction, and electric charging equipment are connected to the grid. The access of these loads will cause great interference to the power grid. Not only will it generate interference harmonics that are integer multiples of the power frequency of 50Hz, but also interharmonics with frequencies greater than 50Hz but not integer multiples of the power frequency (such as 79Hz, 63Hz, 111Hz, etc.), may also produce sub-harmonics with a frequency less than 20Hz but not an integer multiple of the power frequency (such as 9Hz, 13Hz, 11Hz, etc.), the existing energy meter verification device can only generate the power frequency required for the verification of the energy meter Output, can also generate or superimpose 2-21 harmonic output on the basis of power frequency output, that is, the existing electric energy meter verification device can only generate or superimpose harmonics that are integer multiples of power frequency, and cannot generate or On the basis of the power frequency, inter-harmonics and sub-harmonics that are integer multiples of non-power frequency frequencies are superimposed.

At present, the principle of power frequency signal output generated by the verification device of the electric energy meter is: to discretize the sine wave waveform of one cycle into N points, taking 3600 points as an example, the difference between every two discrete points is 0.1°. Each discrete point number and the sine value of the corresponding angle are stored in the RAM in one-to-one correspondence, the discrete point number is used as the storage address of the RAM, and the corresponding angle sine value is used as the stored value. For example, the address of point 1 is 0001, and its value is Asin0.1; the address of point k is: 000k, and its value is Asin0.1k. When working, the CPU sends the values stored in the RAM to the D/A in sequence for digital-to-analog conversion into analog signals, that is, the beat frequency at which the discrete point values are sent from the RAM to the D/A is: 50×3600=180000Hz. The analog signal can be used for verification after being output by the power amplifier. The specific work flow is shown in Figure 1, the working diagram of the first signal source of the original electric energy meter verification device.

The first signal source includes CPU, first memory RAM, digital-to-analog converter D/A, first digital-to-analog converter D/A (1), second digital-to-analog converter D/A (2), driving circuit and voltage frequency converter. As shown in Figure 1.

The method of outputting or superimposing the integer multiple frequency harmonics of the power frequency is the same as above, and the waveform of 1 power frequency cycle is still discretized into 3600 points. Each discrete point number and its corresponding function value are stored in the RAM in one-to-one correspondence, the discrete point number is used as a storage address of the RAM, and its corresponding function value is used as a stored value. The value of point i is:

Mi: the function value of the i-th point of the function

Ak: Amplitude of the kth harmonic

The above function represents the formula for calculating the function value of the i-th point of the composite waveform, which is to add the values of the i-th point of each harmonic that needs to be superimposed. Since the frequency of the integer multiple harmonics of the power frequency is an integer multiple of the frequency of the power frequency signal, the cycle of the envelope curve of the synthesized waveform is the same as that of the power frequency waveform, that is, the synthesized waveform can be fully and accurately represented by 3600 discrete points. This method is very effective for harmonics of integer multiples of power frequency, but it is difficult to achieve harmonics of integer multiples of non-power frequency frequencies. For example, to superimpose harmonics with a frequency of 77Hz on the basis of the power frequency output, then the envelope period of the two frequency sine waves is the least common multiple of the two frequency sine wave periods, namely: T=20×(1000/ 77)=259.74026ms, which is 1000/77=12.99 times of the period of the power frequency waveform. If it is also necessary to ensure that the interval of each sampling point of the power frequency output waveform is 0.1°, the number of stored points must be: 3600×12.99=46753.267, Moreover, the higher the frequency of the superimposed waveform, the more points need to be stored, and the higher the requirements for the calculation amount of the CPU and the storage space of the RAM. The key is that many cycles may be infinite decimals or recurring decimals, so it cannot be realized.

Therefore, it is necessary to find a method for outputting harmonics, sub-harmonics and inter-harmonics of the electric energy meter verification device, so that the electric energy meter verification device can not only output the power frequency and superimpose the integer multiple harmonics of the power frequency, but also output the inter-harmonic, subharmonic. It is used to detect and evaluate the comprehensive error of the electric energy meter, and provides a theoretical basis for studying the influence of inter-harmonic and sub-harmonic on electric energy measurement.

Contents of the invention

The purpose of the present invention is, in order to solve the situation that the energy meter verification device cannot superimpose output sub-harmonics and inter-harmonics on the basis of power frequency output by traditional methods, that is, when there are superimposed sub-harmonics and inter-harmonics in the traditional method, Due to the large envelope period of the synthesized waveform, the period is uncertain, and it may be a non-integer or an infinite cycle of decimals, the present invention proposes an electric energy meter verification device that outputs harmonics, sub-harmonics and simple harmonics. way of waves.

The technical solution of the present invention is that a method for outputting harmonics, sub-harmonics and simple harmonics of an electric energy meter verification device in the present invention retains the original output power frequency waveform of the electric energy meter verification device and can superimpose power frequency integer multiple harmonics The part is called the first signal source, and another sub-harmonic signal source circuit is added, which is called the second signal source. The second signal source only generates sub-harmonics and inter-harmonics.

In the method of the present invention, the output of the first signal source and the output of the second signal source are superimposed and synthesized through an adder built by an operational amplifier; that is, the power frequency signal of the first signal source, the power frequency integer multiple harmonic signal and the second The sub-harmonic signal and inter-harmonic signal output by the signal source are superimposed and synthesized into a waveform signal; then the synthesized signal is output to the power amplifier for amplification and output.

The second signal source includes a main circuit, an amplitude modulation circuit and a frequency modulation circuit.

The main circuit includes a CPU, a second memory RAM (2), and a third digital-to-analog converter D/A (3). When working, the CPU discretizes the sub-harmonic or inter-harmonic signal of one period into 3600 points, each interval is 0.1°; each discrete point number and the sine value of the corresponding angle are stored in the second memory in one-to-one correspondence In RAM (2), the discrete point number is used as the storage address of the second memory RAM (2), and its corresponding angle sine value is used as the stored value; the CPU sends the values stored in the second memory RAM (2) to the third The digital-to-analog converter D/A (3) performs digital-to-analog conversion into an analog signal; the initial phase angle setting and adjustment of the output waveform are also realized through the main circuit; the electric energy meter verification device needs to output three-phase voltage and three-phase current with a total of 6 phases The output, A, B, and C have a phase difference of 120°, and these 6 phases share the data in the third memory RAM (3), but the starting address for reading the data in the second memory RAM (2) is different.

The amplitude modulation circuit includes a CPU, a fourth digital-to-analog converter D/A (4) and a second drive (2) circuit. The amplitude modulation circuit is responsible for adjusting the reference voltage of the third digital-to-analog converter D/A(3) of the main circuit by controlling the amplitude of the DC signal output by the third digital-to-analog converter D/A(3) of the main circuit. A characteristic of the third digital-to-analog converter D/A (3) in the main circuit is that the amplitude of its output signal is proportional to the size of the reference voltage, and the required amplitude digital value is sent to the fourth digital-analog converter through the CPU. Converter D/A (4); the fourth digital-to-analog converter D/A (4) converts the digital value into a reference voltage output as the reference voltage of the third digital-to-analog converter D/A (3) of the main circuit, so That is, the reference voltage of the third digital-to-analog converter D/A (3) can be changed by changing the output voltage of the fourth digital-to-analog converter D/A (4) through the CPU, so as to realize amplitude control of the output signal.

The frequency modulation circuit includes a CPU, a fifth digital-to-analog converter D/A (5) and a second voltage-to-frequency converter V/F (2) conversion circuit. The frequency modulation circuit is responsible for controlling the frequency of the output waveform of the third digital-to-analog converter D/A (3) of the main circuit. Another characteristic of the third digital-to-analog converter D/A (3) is that the frequency of its output signal is proportional to the conversion beat, and the frequency digital value to be set is sent to the fifth digital-to-analog converter D/A ( 5). The fifth digital-to-analog converter D/A (5) converts the digital value into an analog voltage and outputs it to the second voltage-frequency converter V/F (2) conversion circuit, and the second voltage-frequency converter V/F (2) converts The circuit converts the voltage into a frequency signal and outputs it to the second memory RAM (2) and the third digital-to-analog converter D/A (3) as the second memory RAM (2) and the third digital-to-analog converter D/A (3) The number of sending and conversion beats, so that the output voltage of the fifth digital-to-analog converter D/A (5) can be changed by the CPU, and then the third digital-to-analog converter can be changed through the conversion of the second voltage-frequency converter V/F (2). The output frequency of the converter D/A (3) realizes the frequency control of the output signal.

Both the second signal source and the first signal source are controlled by the CPU of the first signal source.

Said adder superimposes and synthesizes using a 2-stage operational amplifier circuit, wherein the first stage adopts an inverse addition circuit, and the second stage adds an inverter.

The adder superposition synthesis circuit is as follows: after the second signal source generates inter-harmonic and sub-harmonic outputs, the output signals of the first signal source and the second signal source are added, wherein the first signal source The signal output of the signal source is connected to the "-" end of the adder through the resistor R1, the other is connected to the resistor Rf, and then connected to the output end of the adder through the resistor Rf; the output of the second signal source is connected to the "-" end of the adder through the resistor R2 , input to the addition circuit; the "+" end of the adder is grounded; one output end of the adder is connected to the "-" end of the inverter through the resistor Rs; the other output end of the adder is connected to the output of the inverter through the resistor Rf terminal; the "+" terminal of the inverter is grounded. Wherein, V1 is the output voltage of the first signal source; V2 is the output voltage of the second signal source.

The specific working principle of the present invention is shown in Fig. 2, a working schematic diagram of power frequency, harmonic, sub-harmonic and inter-harmonic signal generation.

The working principle of the second signal source is: the CPU discretizes the sub-harmonic or inter-harmonic of one cycle into 3600 points, and stores each discrete point number and the sine value of the corresponding angle in the second memory RAM2 Among them, the discrete point number is used as the storage address of the second memory RAM2, and its corresponding angle sine value is used as the stored value. For example, the address of point 1 is 0001, and its value is Asin0.1; the address of point k is: 000k, and its value is Asin0.1k. When working, the CPU sends the values stored in the second memory RAM2 to the third digital-to-analog converter D/A (3) in order for digital-to-analog conversion into analog signals, and the second signal source realizes sub-harmonic or inter-harmonic The key is that the CPU controls the second memory RAM2 to send data to the third digital-to-analog converter D/A (3) and the frequency of the third digital-to-analog converter D/A (3) to perform digital-to-analog conversion to achieve sub-harmonic or intermittent Harmonic frequency.

For example, to realize the sub-harmonic output of 20Hz, the cycle of the sub-harmonic of 20Hz is 50ms, within the cycle of 50ms to realize 3600 points to complete the digital-to-analog conversion, then the CPU controls the second memory RAM2 to the third digital-to-analog converter D /A (3) sends 3600 points to the third digital-to-analog converter D/A (3) for digital-to-analog conversion, and the conversion frequency is: f=3600/50=72Hz.

Similarly, when the 80Hz interharmonic output is to be realized, the period of the 80Hz interharmonic is 12.5ms, and the digital-to-analog conversion of 3600 points must be completed within 12.5ms, that is, the CPU controls the second memory RAM2 to the third digital-to-analog The converter D/A (3) sends numbers, and the frequency of the third digital-to-analog converter D/A (3) for digital-to-analog conversion is: f=3600/12.5=288Hz.

After the inter-harmonic and sub-harmonic outputs are generated, the output signals of the first signal source and the second signal source are added, wherein the signal output of the first signal source is connected to the V1 terminal of Figure 3 and input to the addition circuit; The output of the second signal source is connected to the V2 terminal in FIG. 3 and input to the adding circuit. The specific circuit of the adder is shown in Figure 3: a schematic diagram of the synthesis of power frequency and harmonic signal sources and sub-harmonic and inter-harmonic signal sources. The adder circuit uses a two-stage operational amplifier circuit, of which the first stage uses The output of the reverse addition circuit is Vo=-Vi, so an inverter is then added.

R1=R2=Rf=Rs in Fig. 3, Vo=-Rf/Rs[(-Rf/R1)×V1+(-Rf/R2)×V2]. Therefore, the final output of the adder is Vo=V1+V2.

The beneficial effect of the present invention is that the present invention adds a set of sub-harmonic or inter-harmonic signal generators on the basis of the original power frequency output and power frequency integer multiple harmonic output of the electric energy meter verification device, and then 2 channels The signals are added and synthesized by the adder built by the operational amplifier circuit and then output, which solves the problem that it is difficult to superimpose any harmonics on a set of signal sources in the traditional method.

The invention is applicable to the verification device of the electric energy meter not only to output power frequency signals and power frequency integer multiple harmonic signals, but also to superimpose or output sub-harmonics and inter-harmonics for researching and analyzing the influence of harmonics on electric energy measurement.

Description of drawings

Fig. 1 is a working schematic diagram of the signal source of the original electric energy meter verification device;

Figure 2 is a schematic diagram of the generation of power frequency, harmonic, sub-harmonic and inter-harmonic signals;

Fig. 3 is a schematic diagram of synthesizing work of power frequency and harmonic signal sources and sub-harmonic and inter-harmonic signal sources.

Detailed ways

The specific embodiment of the present invention is as follows:

The composition and working principle of the signal source of power frequency, harmonic, sub-harmonic and inter-harmonic in this embodiment are shown in Figure 2. The second signal source of sub-harmonic and inter-harmonic includes main circuit, amplitude modulation circuit and frequency modulation circuit.

The main circuit of the second signal source of the present embodiment includes a CPU, a second memory RAM (2) and a third digital-to-analog converter D/A (3). During work, the CPU converts a cycle of sub-harmonic or inter-harmonic signals Discrete into 3600 points, each interval is 0.1°. Store each discrete point number and the sine value of the corresponding angle in the second memory RAM (2) in one-to-one correspondence, the discrete point number is used as the storage address of the second memory RAM (2), and the corresponding angle sine value is used as the stored value . For example, the address of point 1 is 0001, and its value is Asin0.1; the address of point k is: 000k, and its value is Asin0.1k. When working, the CPU sends the values stored in the second memory RAM (2) to the third digital-to-analog converter D/A (3) in sequence for digital-to-analog conversion into analog signals. The setting and adjustment of the initial phase angle of the output waveform is also realized through the main circuit. For example, if the initial phase angle of the output waveform is set to 30°, then the CPU can start from the 300th point to fetch data from the first RAM. The watt-hour meter verification device needs to output three-phase voltage and three-phase current, a total of 6-phase output, A, B, C each have a difference of 120°, these 6 phases share the data in the third memory RAM (3), and only read the second memory The start addresses of data in RAM (2) are different.

The amplitude modulation circuit of the second signal source in this embodiment is composed of CPU, the fourth digital-to-analog converter D/A (4) and the second drive (2) circuit. The amplitude modulation circuit is responsible for controlling the third digital-to-analog converter D/A of the main circuit. A(3) outputs the amplitude of the DC signal to adjust the reference voltage of the third digital-to-analog converter D/A(3) of the main circuit. A characteristic of the third digital-to-analog converter D/A (3) in the main circuit is that the amplitude of its output signal is proportional to the size of the reference voltage. The present invention sends the required amplitude digital value to the fourth through the CPU. Digital-to-analog converter D/A (4), the fourth digital-to-analog converter D/A (4) converts the digital value into a reference voltage output as the reference voltage of the third digital-to-analog converter D/A (3) of the main circuit , so that the CPU can change the output voltage of the fourth digital-to-analog converter D/A (4) to change the reference voltage of the third digital-to-analog converter D/A (3), so as to realize the amplitude control of the output signal.

The frequency modulation circuit of the second signal source in this embodiment includes CPU, the fifth digital-to-analog converter D/A (5) and the second voltage-frequency converter V/F (2) conversion circuit part, and the frequency modulation circuit is responsible for controlling the third frequency of the main circuit. The frequency of the digital-to-analog converter D/A (3) output waveform. Another characteristic of the third digital-to-analog converter D/A (3) is that the frequency of its output signal is proportional to the conversion beat. The present invention sends the required frequency digital value to the fifth digital-to-analog converter D/A through the CPU. A(5), the fifth digital-to-analog converter D/A(5) converts the digital value into an analog voltage and outputs it to the second voltage-frequency converter V/F (2) conversion circuit, the second voltage-frequency converter V/ The F (2) conversion circuit converts the voltage into a frequency signal and outputs it to the second memory RAM (2) and the third digital-to-analog converter D/A (3) as the second memory RAM (2) and the third digital-to-analog converter D /A(3) sending number and conversion beat, so that the output voltage of the fifth digital-to-analog converter D/A(5) can be changed by the CPU, and then transformed by the second voltage-frequency converter V/F(2) to The output frequency of the third digital-to-analog converter D/A (3) is changed to realize the frequency control of the output signal.

This embodiment is divided into two sets of signal sources. The first signal source is responsible for outputting power frequency signals and integer multiple harmonics of the power frequency; the second signal source is responsible for outputting sub-harmonics and inter-harmonics. The working principle of the second signal source is basically the same as that of the first signal source, and the output of harmonics of different frequencies can be realized through the frequency modulation circuit as mentioned above. The output waveforms of the first signal source and the second signal source are added and synthesized by the adder constructed by the operational amplifier, and then output through the inverter and realized that the electric energy meter verification device can output power frequency, power frequency integer multiple harmonics, sub Harmonics and interharmonics. For details, please refer to attached drawing 3: a schematic diagram of the synthesis of power frequency and harmonic signal sources and sub-harmonic and inter-harmonic signal sources.

Claims (3)

1. a kind of method of electric energy meter calibrating apparatus output harmonic wave, subharmonic and monochromatic wave, including use electric energy meter calibration dress Set original the first signal source that can export power frequency waveform, stackable power frequency integer harmonics, which is characterized in that the method also increases Add a signal source for only generating subharmonic and m-Acetyl chlorophosphonazo, is second signal source；The method by the output of the first signal source with The output in second signal source is superimposed synthesis by the adder that operational amplifier is built；First can be believed the power frequency of signal source Number, power frequency integer harmonics signal and second signal source output rd harmonic signal, m-Acetyl chlorophosphonazo Signal averaging synthesize a waveform Signal；Composite signal is output to power amplifier amplification output again；

The second signal source includes main circuit, modulation circuit and FM circuit；

The main circuit includes CPU, second memory, third digital analog converter；When work CPU by the subharmonic in 1 period or M-Acetyl chlorophosphonazo signal discrete is divided into 0.1 ° at 3600 points between each；One by one by the sine value of each discrete period and its corresponding angle Correspondence is stored in second memory, storage address of the discrete period as second memory, corresponding angle sine value conduct Store numerical value；The numerical value being stored in second memory is sent to third digital analog converter and carries out digital-to-analogue conversion change by CPU in order At analog signal；The starting phase angle of output waveform is arranged and adjustment is realized also by main circuit；Electric energy meter calibrating apparatus needs defeated Going out three-phase voltage totally 6 mutually to export with three-phase current, A, B, C respectively differ 120 °, this 6 phase all shares the data in third memory, The initial address for only reading data in second memory differs；

The modulation circuit includes CPU, the 4th digital analog converter and the second driving circuit；The modulation circuit is responsible for passing through control The amplitude of main circuit third digital analog converter output direct current signal adjusts the benchmark electricity of main circuit third digital analog converter to realize Pressure；One characteristic of third digital analog converter in main circuit be exactly its output signal amplitude and reference voltage size at just Than the amplitude digital value of required setting being sent to the 4th digital analog converter by CPU, the 4th digital analog converter is by the digital value Reference voltage of the reference voltage output as main circuit third digital analog converter is converted to, CPU can be passed through in this way and change the 4th The output voltage of digital analog converter changes the reference voltage of third digital analog converter, realizes the amplitude control of output signal；

The FM circuit includes CPU, the 5th digital analog converter and second voltage frequency converter；The FM circuit is responsible for control The frequency of main circuit third digital analog converter output waveform processed；Another characteristic of third digital analog converter is exactly its output signal Frequency it is directly proportional to conversion beat, the frequency digital value of required setting is sent to by the 5th digital analog converter by CPU, the 5th The digital value is converted to analog voltage and is output to second voltage frequency converter, second voltage frequency converter by digital analog converter It is converted to frequency signal and is output to second memory and third digital analog converter as second memory and third digital analog converter Send number and conversion beat, the output voltage of the 5th digital analog converter can be changed by CPU in this way, then through second voltage frequency Converter transform changes the output frequency of third digital analog converter, realizes the FREQUENCY CONTROL of output signal.

2. a kind of method of electric energy meter calibrating apparatus output harmonic wave, subharmonic and monochromatic wave according to claim 1, feature Be, adder superposition synthesis has used 2 grades of operational amplification circuits, the wherein first order using reversed add circuit, The second level adds a phase inverter again.

3. a kind of method of electric energy meter calibrating apparatus output harmonic wave, subharmonic and monochromatic wave according to claim 1, feature It is, the adder superposition combiner circuit is as follows：

After the second signal source produces m-Acetyl chlorophosphonazo and subharmonic output, then by the output of the first signal source and second signal source Signal is added, wherein the signal output of the first signal source connects the "-" end of adder by mono- tunnels resistance R1, another way connects Resistance Rf, then the output end by resistance Rf connection adders；The output in second signal source 2 connects adder by resistance R2 "-" end, is input to add circuit；The "+" end of adder is grounded；The output end of adder is reversed by resistance Rs connections all the way The "-" end of device；The output end that the another way of the output end of adder passes through resistance Rf connection reversers；The "+" of reverser terminates Ground；R1=R2=Rf=Rs, Vo=-Rf/Rs [(- Rf/R1) × V1+ (- Rf/R2) × V2]；Therefore the final output of adder As a result it is Vo=V1+V2；

Wherein, V1 is the first signal source output voltage；V2 is second signal source output voltage.