CN2700889Y - Real time electrical energy and mass integrated analyzer - Google Patents

Abstract

The utility model discloses a real time electrical energy and mass integrated analyzer, which comprises a DSP processor, a three-phase input of the current and voltage, an A/D converting circuit, an RAM circuit, a filtering and adjusting circuit and a timing circuit. The A, B, C three-phase voltage of the power network and the six path of the current signal are converted into voltage signals with suitable amplitude after sampled by the sensor. A high precision A/D respectively does the sample collection and the data conversion, and then the high precision A/D is input into the DSP. The filtering and adjusting circuit is input into the DSP processor through the timing circuit. The DSP processor uses the Fast Fourier Transform (FFT) arithmetic to do the spectrum analysis of the discrete series of the signal sampling. Hence, the power system frequency and the various harmonic of the signals can be calculated in real time. Then, the computing result can be further used for calculating the active power, the reactive power, etc. The utility model has advantages of high real time performance, high precision and high reliability.

Description

Real-time quality of power supply synthesis analyzer

One, technical field

The utility model relates to real-time quality of power supply synthesis analyzer, especially comprises the quality of power supply synthesis analyzer of sampling analysis calculating mains frequency.

Two, background technology

The frequency quality is one of important indicator of weighing the power supply grid power quality problem.Along with the development of Power Electronic Technique, nonlinear device and equipment obtain application more and more widely on the one hand, and the wave form distortion of electrical network is more and more serious, and harmonic content also significantly increases; Along with various complexity, precision, constantly universal to the consumer of quality of power supply sensitivity, people are more and more higher to the requirement of the quality of power supply, therefore are necessary index implementation monitoring and control to the qualities of power supply such as harmonic wave of electrical network on the other hand.Still there is not at present a kind of real-time sampling analysis to calculate the quality of power supply synthesis analyzer of mains frequency.Certainly, the total voltage amplitude, current amplitude can be calculated meritorious, reactive power, and parameters such as applied power are also extremely important.

Three, summary of the invention

The purpose of this utility model is: propose the quality of power supply synthesis analyzer that mains frequency is calculated in a kind of sampling analysis.The utility model can sampling analysis calculate mains frequency, obtains the total voltage amplitude simultaneously, and current amplitude can be calculated meritorious, reactive power, applied power etc.

The utility model purpose is achieved in that real-time quality of power supply synthesis analyzer, it is characterized in that comprising dsp processor, the three-phase input end of electric current and voltage, the A/D change-over circuit, the RAM circuit, whole ripple of filtering and timing circuit constitute, the A of electrical network, B, C three-phase voltage and current signal six road signals are transformed into the suitable voltage signal of amplitude behind sensor sample, high-precision A/D samples respectively and data-switching, input DSP, the whole wave circuit of filtering is also imported dsp processor behind timing circuit, utilize the fast Fourier transform (FFT) algorithm to carry out the spectrum analysis of the discrete series of signal sampling by dsp processor, thereby calculate mains frequency, the each harmonic of signal, and further utilize result of calculation to gain merit, other calculating such as reactive power.Communicate by letter with PC by interface, carry out operations such as data presentation, storage, printing by the high-level software on the PC, realize the function of virtual instrument.

Improvement of the present utility model is: dsp processor has been reserved the I/O mouth, and its output connects protective relay, provides the outlet signal according to result of calculation and preset threshold value, directly controls the action of protective relay.

The principle of the present utility model and the course of work:

Quality of power supply real time comprehensive analyser is to the monitoring effect of some index parameter of the quality of power supply, six tunnel signal transformations become the suitable voltage signal of amplitude with current signal to A, B, the C three-phase voltage of electrical network, sample respectively and data-switching with high-precision A/D, dsp processor TMS320F206 utilizes the fast Fourier transform (FFT) algorithm to carry out the spectrum analysis of the discrete series of signal sampling, thereby calculate the each harmonic of signal, and further utilize other calculating such as result of calculation is gained merit, reactive power.Owing to reserved the I/O mouth, can provide the outlet signal according to result of calculation and preset threshold value, directly control the action of protective relay.

1. principle

Voltage and current in the electric power transmission line is not desirable 50Hz sinusoidal signal, be subjected to the influence of nonlinear load, the waveform of electrical network can distort, still periodic function after the distortion, and satisfy the Di Liheli condition, can come the stack that resolve into a series of first-harmonics and harmonic wave to voltage and current with Fourier series method.

$u\left(t\right)=U_0+\underset{n=1}{\overset{\∞}{\mathrm{\Σ}}}{U}_n\sin (\mathrm{n\ωt}+{\mathrm{\α}}_n),$ $i\left(t\right)=I_0+\underset{n=1}{\overset{\∞}{\mathrm{\Σ}}}{I}_n\sin (\mathrm{n\ωt}+{\mathrm{\β}}_n)$

In the formula, U ₀, I ₀Be the DC component of voltage, electric current, Un, In are the peak value of each harmonic amplitude.The difference of α n and β n is humorous angle.

Cycle continuous time signal to electrical network carries out real-time sampling, and discrete sample sequence is carried out the time-frequency domain conversion with fft algorithm, can analyze the amplitude and the phase place situation of first-harmonic and each harmonic very easily, realizes the monitoring of harmonic wave.In addition, there is phase differential between the phase voltage on each road and the phase current in the electrical network, to voltage and current signal Synchronization sampling and carry out the FFT conversion, just can calculates the humorous angle of each harmonic, measure gaining merit and reactive power of each harmonic accurately.In fact, fft algorithm is to calculate the idle method the most accurately of electric network active.And calculate for FFT, if the end points of sampled data set is discontinuous, just need to introduce window function during calculating, thereby increase the fussy degree of calculating.And satisfying the correlated sampling principle, and the data point set of sampling just in time is under the situation of complete cycle, the sampled data set two-end-point is continuous, just can regard the sampled signal sequence as infinite periodic signal, FFT is calculated become simple.The method of sampling that satisfies the correlated sampling principle should satisfy following formula.

$\frac{M}{N}=\frac{F_T}{F_S}$

Herein: M: the sampling period number is necessary for odd number.

N: total sampling number, for example the fft algorithm for base 2 is necessary for 2 power.

FT: the fundamental frequency of input simulating signal.

FS: sample frequency.

The FFT butterfly computation itself requires sampled point numerical value when being 2 power, calculates the fastest; For obtaining best testing efficiency and minimizing test duration, M and N require and can not reduce.In fact, the M=1 that gets when we calculate, N=1024, promptly the phase is realized 1024 point samplings weekly, sample frequency is 1024 times of fundamental frequency like this.Because be subjected to the influence of load, mains frequency is not the 50Hz that fixes, can fluctuation up and down about 50Hz.Therefore on hardware is realized, cannot use fixed frequency sampling, but will adjust sample frequency in real time according to the frequency of electrical network.

FFT calculates the complex representation of each time electric current and voltage harmonic wave, has therefore comprised the amplitude and the phase information of voltage and current.U _i=U _i∠ φ _i, I=I _i∠ φ _i, total voltage amplitude then ${\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="Y20042002422400081.png"\; state="\{\{state\}\}">U</figure-callout>}}^2={U_0}^2+\underset{i=1}{\mathrm{\&Sigma;}}{{\mathrm{<figure-callout\; id="2"\; label="U\; i"\; filenames="Y20042002422400081.png"\; state="\{\{state\}\}">U</figure-callout>}}_i}^2,$ Current amplitude $I^{}$ ${}^2={I_0}^2+\underset{i=1}{\mathrm{\&Sigma;}}{I_i}^2,$ Can calculate meritorious, reactive power p=∑ Re (U thus again _iI _i),

$Q=\underset{i}{\mathrm{\&Sigma;}}\mathrm{Im}\left(U_i{I}_i\right),$ Applied power: S=UI.

High-precision A/D samples respectively and data-switching, input DSP, the whole ripple of filtering is taken a sample to mains frequency after timing circuit is also imported dsp processor, utilize the fast Fourier transform (FFT) algorithm to carry out the spectrum analysis of the discrete series of signal sampling by dsp processor TMS320F206, thereby calculate the each harmonic of signal, and further utilize other calculating such as result of calculation is gained merit, reactive power.Owing to reserved the I/O mouth, can provide the outlet signal according to result of calculation and preset threshold value, directly control the action of protective relay.

The function that the software that moves on the dsp processor is finished is as follows: control A/D sampling, and carry out FFT and calculate, calculate meritorious, reactive power, harmonic wave and power monitoring also provide the outlet signal, transmit result calculated by interface to PC.

Characteristics of the present utility model are:

1. real-time

Frequency analysis equipment in the past is not owing to adopt dsp processor, and the computing execution time is too slow, so basic in fact not to the real-time monitoring capability of harmonic wave.Adopt the dsp processor TMS320F206 of TEXAS company on the power quality analyzer hardware that we will do now, dsp processor is because fast operation, it is the high speed device that is specifically applied to digital signal processing, can carry out FFT fast calculates, calculate the frequency spectrum of signal, thereby realize real real-time monitoring.

2. high precision

The A/D of our employing is 14 max125 of high speed, not only realizes high-speed data acquisition, and has realized high-precision measurement.

3. high reliability

Adopt phaselocked loop that the first-harmonic frequency multiplication is started the A/D conversion on the frequency analysis device design in the past, and the poor anti jamming capability of phase-locked loop circuit, the reliability of circuit is not enough.The counting frequency division has also been avoided the use of phaselocked loop, can improve the reliability of equipment performance greatly.And the dsp chip antijamming capability of 5v is strong.

Four, description of drawings

Fig. 1 is a hardware block diagram

Fig. 2 software flow pattern

Fig. 3 is the utility model circuit diagram

Five, embodiment

The hardware block diagram of DSP and PC as shown in Figure 1, software block diagram and process flow diagram are as shown in Figure 2.

As shown in Figure 3, the core processor of the utility model circuit adopts 16 fixed DSP processor TMS320F206 of texas, and F206 is a kind of dsp processor that extensively is used in Industry Control, maximum operation frequency 40MHz, 4 grades of pipeline depth have the flash of two 16k in the sheet.A/D adopts 14 high-speed a/ds, the 8 passage max125 of MAXIM, and each passage switching time is 3 μ s only.Circuit on the plate is a core with dsp processor TMS320F206 mainly, and sheet has been expanded two RAM CY7C199, NVRAM DS1644 outward.Peripheral circuit comprise A/Dmax125, timing circuit 82C54, liquid crystal interface (JP2) partly, keyboard interface (JP1) part.GAL20V8 produces peripheral chip selection signal.Six tunnel switching signals are imported A/D through amplifier, and wherein one tunnel process filtering (max291) shaping (max903) back access 82C54 carries out frequency counting.The interface circuit of DSP and PC is that max232.74HC273 connects optocoupler for exporting signal.

The utility model has following function, the test frequency deviation:

Because the influence of load in the electrical network, mains frequency can fluctuate up and down about 50Hz, and the IF harmonic analysis instrument can test out the fundamental frequency of electrical network accurately.

Frequency analysis:

Frequency analysis comprises the calculating and the analysis of voltage, current harmonics.

Frequency analysis equipment in the past is not owing to adopt dsp processor, and the computing execution time is too slow, so basic in fact not to the real-time monitoring capability of harmonic wave.Adopt dsp processor on the harmonic analysis instrument hardware that we will do now, dsp processor is the high speed device that is specifically applied to digital signal processing, thereby realizes real real-time monitoring.And the employing of high-speed, high precision A/D not only reaches weekly the high-speed sampling of 1024 in ripple easily, and measuring accuracy can reach 1 ‰ at least, also is higher than the measuring accuracy of harmonic analysis instrument in the past.

Power detection:

Obtain just can and then gain merit behind the each harmonic, the calculating of idle and applied power.Meritorious and the reactive power test that utilizes the electrical network that fft algorithm calculates is a method of testing the most accurately.Meritorious and the reactive power of the IF harmonic analysis instrument that we will do is calculated precision and can be reached 1 ‰ at least.

The harmonic wave monitoring:

This IF harmonic analysis instrument is by external computing machine, with high-level software equipment carried out program control, exchanges data and monitoring etc.And reserve the I/O mouth on the plate, external exit relay can be by being provided with the monitoring function of realizing harmonic wave.

The voltage three-phase imbalance:

Because the threephase load reason of unbalanced of electrical network, three-phase voltage vector sum is not 0.Utilize the first-harmonic of three-phase voltage and harmonic amplitude and phase angle can calculate imbalance of three-phase voltage.

Claims (2)

1, real-time quality of power supply synthesis analyzer, it is characterized in that comprising dsp processor, the three-phase input end of electric current and voltage, the A/D change-over circuit, the RAM circuit, whole ripple of filtering and timing circuit constitute, the A of electrical network, B, C three-phase voltage and current signal six road signals are transformed into the suitable voltage signal of amplitude behind sensor sample, high-precision A/D samples respectively and data-switching, input DSP, the whole wave circuit of filtering is also imported dsp processor behind timing circuit, utilize the fast Fourier transform (FFT) algorithm to carry out the spectrum analysis of the discrete series of signal sampling by dsp processor, thereby the real-time mains frequency that calculates, the each harmonic of signal, and further utilize result of calculation to gain merit, reactive power is calculated.

2, by the described real-time quality of power supply synthesis analyzer of claim 1, it is characterized in that dsp processor reserved the I/O mouth, its output connects protective relay.

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