JPS6073368A - Harmonic wave analyser - Google Patents

Abstract

PURPOSE:To make it possible to accurately measure the phase difference of the fundamental wave of a synchronous signal and a input signal by sampling a power system wave form under a steady state at the multiplied frequency of its frequency to store the same in memory while subjecting the same to Fourier analysis. CONSTITUTION:A harmonic wave analyser permits a pulse delay circuit 11 to delay the rising zero cross signal (g) of a synchronous signal fundamental wave being the output of a comparator 6 over a difinite time and the output pulse (h) of this circuit 11 is inputted not only to a frequency multiplier circuit 7 but also to CPU3. By this method, the rising of the output pulse (h) of the pulse delay circuit 11 is coincided with the rising zero cross point of the fundamental wave component of a synchronous signal (e) prior to being inputted to a fundamental wave passing band pass filter 5 and the frequency multiplier circuit 7 generates a sampling pulse (b) while CPU3 begins to collect data. As a result, the phase difference of an input signal (a) to the fundamental wave of the synchronous signal (e) can be accurately measured.

Description

Detailed Description of the Invention This invention samples a current power system waveform at a frequency that is multiple times its frequency, A/D converts it, stores it in memory, and performs Fourier analysis to improve the harmonics of the waveform. This invention relates to a harmonic analyzer that performs wave analysis.

As shown in FIG. 1, a conventional harmonic analyzer uses an amplifier 1 to adjust the level of an input signal (a power system waveform in a fixed state) to an appropriate level, and then converts the input signal a to an appropriate level using an A/D converter 2. A/D conversion is performed based on San 7°Ringz<bus b. When the sampling pulse b is input, the A/D converter 2 samples the input 1 word 3, performs A/D conversion, and converts the A/D conversion completion signal C to C after the completion of the A/D conversion.
Output to PU 3.

On the other hand, either the input 1i % si or the external synchronization signal d (having a fundamental wave of the same frequency as the power system waveform fundamental wave il) is switched to the Domei signal e (@2
Figure) is selected as the fundamental wave passing bandpass filter 5.
The DC component and harmonics higher than the tiS2 harmonic are removed there, and this fundamental wave passing bandpass filter 5
The output f (Fig. 12) is waveform-shaped by the capacitor 6. When the rising edge of the synchronizing signal fundamental wave, which is the output of the comparator 6, is zero-crossing signal g (see FIG. 2), the frequency multiplier circuit 7 generates a sampling pulse b (see FIG. 2) which is synchronized with the rising zero-crossing signal g (see FIG. 2). All occur.

When the CPU 3 receives the rising zero cross signal g of the synchronizing signal fundamental wave from the comparator 6, it starts collecting data from the wax, and collects A/D conversion data for one cycle of the input signal a (for example, the sampling pulse b). If the frequency is 128 times the fundamental wave, 128 points) are stored in the memory 9 via the data bus 8.

The CPU 3 performs Fourier analysis on the data and outputs the magnitude of each harmonic and the phase difference of the synchronization signal e with respect to the fundamental wave to the printer 10.

FIG. 3 is a flow diagram showing the flow of the operation of the CPU 3. The CPU 3 waits for the rising zero cross signal fg of the synchronization signal fundamental wave to be input, and when it is input, sets the number of data to be acquired, for example 128, in the built-in data acquisition counter, and then the A/D Waiting for the conversion completion signal, and each time it is input, the A/D conversion data is stored in the memory 9 by bending the data bus 8, and the operation of subtracting the value 'f:1 of the data acquisition counter is repeated. conduct,
When the value of the data acquisition counter reaches 0, memory 9
The data stored in is Fourier transformed to determine the content rate and phase of each missing harmonic, and this is output to the printer 10.

However, in such conventional harmonic analyzers,
The synchronization signal e has a waveform consisting only of the fundamental wave component due to the fundamental wave passing bandpass filter 5, but by passing through the fundamental wave passing bandpass filter 5, the phase of the fundamental wave component also changes. , there was a drawback that the phase difference between the input signal a and the fundamental wave of the synchronization signal e could not be accurately measured.

Therefore, an object of the present invention is to provide a harmonic analyzer that can accurately measure the phase difference between the fundamental wave of a synchronization signal and an input signal.

An embodiment of the present invention will be described based on FIGS. 4 and 5. As shown in FIG. 4, this harmonic analyzer delays the rising zero cross signal g (FIG. 5) of the Domei signal fundamental wave, which is the output of the comparator 6, by a pulse delay circuit 11 for a certain period of time. The output pulse h (FIG. 5) of the circuit 11 is input to the frequency multiplier circuit 7 and also to the CPU 3, and the other configuration is the same as that of FIG. 1.

The pulse delay circuit 11 compensates for the phase change of the fundamental wave component due to the fundamental wave passing bandpass filter 5,
Specifically, the delay time is adjusted so that the phase delay of the fundamental wave 4 overband bus filter 5 and its own delay time add up to exactly 360 degrees. The above delay time is
This time can be calculated in advance from the fundamental frequency of the power system waveform and the frequency e-phase characteristic of the fundamental wave passing bandpass filter 5.

With this configuration, the rise of the fundamental wave component of the synchronizing signal e (FIG. 5) before the rise of the output pulse h (FIG. 5) of the pulse delay circuit 11 is input to the fundamental wave passing bandpass filter 5. The frequency multiplier circuit 7 synchronizes (synchronizes) with the zero-crossing point of the output pulse h, and the frequency multiplier 7 outputs the sampling pulse b (
5) and the CPU 3 starts data collection, it is possible to accurately measure the phase difference between the input signal a and the fundamental wave of the synchronization signal e.

Note that the other operations are similar to those shown in FIG. Further, in the diagram @5, f indicates the output of the fundamental wave passing bandpass filter 5.

As described above, the harmonic analyzer of the present invention includes an analog-to-digital converter that converts a power grid waveform in a steady state from analog to digital, and a synchronizer having a fundamental wave having the same frequency as the fundamental wave of the power grid waveform. A fundamental wave passing bandpass filter that extracts the fundamental wave of a signal, a waveform shaping circuit that shapes the output of the fundamental wave passing filter, and a waveform shaping circuit that delays the rise of the output pulse of this waveform shaping circuit by a certain period of time. a pulse delay circuit that scatters the rising edge of its own output pulse to the rising zero cross of the fundamental wave of the synchronous signal by dispersing the rising edge of the output pulse of the synchronous signal; a frequency multiplier circuit that generates a sampling pulse with a frequency twice as high as that of the frequency multiplier and supplies it to the analog-to-digital converter;
In response to the rise of the output pulse of the pulse extension circuit, the output data of the analog-to-digital converter is collected once, and the collected data is subjected to Fourier analysis. The fundamental wave of the synchronization signal and the constant scrap that is the input signal:! This has the effect that the phase difference with the current power system waveform can be accurately measured as Q+.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional harmonic analyzer, Fig. 2 is a waveform diagram of each part thereof, Fig. 39 is a flowchart for explaining its operation, and Fig. 4 is a block diagram of an embodiment of the present invention. , FIG. 5 is a waveform chart of each part.

Claims (1)

[Claims] An analog-to-digital converter that converts the power system and shape from analog to digital, located in Takechohaku, and a fundamental wave that extracts the fundamental wave of the Domei signal that has the same frequency as the fundamental wave of the power system waveform. A pass band bus filter, a waveform shaping circuit that shapes the waveform of the output of the basic s i A pulse delay circuit that causes the rise of the fundamental wave of the same amount f1 to coincide with the zero cross, and a pulse delay circuit that synchronizes the rise of the fundamental wave of the same amount f1 with the zero cross, and a pulse delay circuit that synchronizes the rise of the fundamental wave of the same amount f1 with the zero cross direction, a frequency multiplier circuit that generates a sampling pulse with a frequency twice as high as that of the frequency multiplier and supplies it to the analog-digital converter; and a frequency multiplier circuit that generates a sampling pulse with a frequency twice as high as that of the frequency multiplier, and collects output data of the analog-digital converter in response to a rising edge of an output pulse of the pulse delay circuit. A harmonic analyzer equipped with a data collection/processing section that performs Fourier analysis on the acquired data.