CN201364361Y - Variable-frequency harmonic measurement device for power system - Google Patents

Abstract

The utility model relates to a variable-frequency harmonic measurement device for a power system, which comprises a DSP unit, an AC unit, a power supply unit, an input/output unit and a display unit, wherein the power supple unit is directly communicated with other modules; the AC unit performs the conversion of an input AC signal; and the DSP unit is connected with the AC unit, the display unit and the input/output unit. Therefore, the variable-frequency harmonic measurement device achieves the measurement of harmonics of the power system and is characterized by a wide measurement range, high measurement accuracy, good real-time performance, a wide application range, low cost and convenient operation and maintenance.

Description

Frequency-conversion harmonic measuring device of electrical power system

One, technical field

The utility model relates to the frequency-conversion harmonic measuring device that the DSP technology combines with fast Fourier algorithm.Belong to the power system harmonic measurement technical field.

Two, background technology

Existing harmonic measure technology and analytical instrument, part adopts common single-chip microcomputer as CPU, external analog to digital converter, and storer and software formation microcomputer electric power harmonic analysis instrument device, such frequency analysis device precision is low, real-time is relatively poor, can not satisfy the requirement of power industry fast development.Also there is the fractional harmonic surveying instrument to adopt the POWERPC chip, adopted the method for fixed frequency sampling, this scheme cost height, software processes complexity as handling core.

Three, summary of the invention

The utility model is in order to overcome the deficiency that existing harmonic measuring device measuring accuracy is low, real-time is poor, cost is high, and a kind of frequency-conversion harmonic measuring device of electrical power system cheaply that can quick and precisely measure Harmonious Waves in Power Systems is provided.Its technology is achieved in that and comprises the DSP unit, exchanges unit, power supply unit, opens into the structure of leaving unit and display unit, it is characterized in that: its connect adopt DSP unit and power supply unit all respectively with exchange unit, display unit, open into leaving the unit and be connected; It is to adopt DSP to be connected with 16bit BUS that the inside of DSP unit connects, and DSP connects display unit by HPI, and DSP is connected with PC by RS485, and DSP is connected with frequency measurement circuit by external interrupt; 16bit BUS is connected with AD with FLASH, SDRAM; Then filtering is connected AD with Order RC; To the sampling interval of input simulating signal according to the frequency dynamic adjustment that accurately records, i.e. frequency-change sampling; DSP unit, display unit have all adopted the CPU intelligent controller; The CPU of DSP unit is the high-performance embedded dsp processor of low-cost low-power consumption; Carry out communication by the HPI interface between DSP unit, the display unit; Power supply unit has adopted Switching Power Supply; Its data handling procedure is:

(1) by signal conditioning circuit input voltage signal is converted to the standard square-wave signal of answering with dfundamental-harmonic pair, comes accurate survey frequency by the external interrupt of DSP again.Dynamically arrange timer according to the frequency that records, regulate the sampling interval to each road input simulating signal to be measured, DSP samples at interval according to this, and the result is stored in the cyclic buffer; Sampled result is handled, carried out discrete Fourier transform (DFT) then; Calculate harmonic data, show by display unit,

(2) the DSP unit adopts dsp chip as processor, and display unit then adopts independently 8051 single-chip microcomputers,

(3) functions such as analog to digital conversion, Measurement Algorithm calculating, result of calculation storage, communication are finished in the DSP unit; The DSP unit is the core of whole device, based on TMS320VC55X series digit signal processor, external 16 bit A/D converters and high capacity FLASH, SDRAM storer, in real time electric power signal is detected, simultaneously measurement result is done further processing, kept 485 general ports simultaneously, adopt the MODBUS communications protocol, communication between support equipment realizes Long-distance Control;

The interchange unit will be imported the forceful electric power conversion of signals and become amplitude to be ± the interior voltage signal of 5V scope, will import simultaneously with output and do the photoelectricity isolation, send the second order active low-pass filter circuit output signal, deliver to DSP unit AD input end then.

DSP unit software section comprises that frequency measurement, frequency acquisition setting, AD interrupt the communication of collection, image data management, digital signal processor, filtering wave, computational data storage, event report and display unit, the DSP unit keeps 485 ports, needing to realize with the communication of remote platform, support the MODBUS communications protocol

(4) power supply unit input alternating current-direct current 85V--265V, output can supply the working power of other each cell operation,

(5) display unit provides man-machine interface; display unit and DSP unit carry out communication according to certain agreement by the HPI port; show measurement result in real time, can reach different defencive functions by the selection setting measurement parameter of button simultaneously, and parameter is kept in the ferroelectric memory.Advantage and the effect implemented after this technology are: measurement range is wide: realize harmonic measure based on discrete Fourier transform (DFT), the amplitude that comprises each harmonic, electric current, voltage, frequency, power, electric degree, power factor, requirement etc., be applicable to that simultaneously input signal fundamental frequency scope can be at 10Hz-100Hz: accuracy height: adopt 16 high-speed AD, sampling 256 points in phase weekly, sample frequency is benchmark with the signal frequency, under sample frequency and the asynchronous situation of signal frequency, can in time proofread and correct sample frequency, signal harmonic is carried out accurate tracking measurement, independent single-chip microcomputer is adopted in the display part simultaneously, the HPI communication does not take the DSP time substantially, do not influence the DSP computing: real-time is good: DSP dominant frequency 300MHZ, have paired multiplier, can measure in real time 31 subharmonic, provide additional functions simultaneously: applied widely: adopt Switching Power Supply, be applicable to the input of wide region power of alterating and direct current: cost is low: TMS320VC55X is the high digital processing chip of a cost performance, remaining chip is low such as equal costs such as SDRAM: convenient operating maintenance: the single-chip microcomputer in the display unit is as auxiliary processor, carry out communication according to certain agreement and DSP unit, have keyboard and LCD, for this device provides perfect human interface function.

Four, description of drawings

Fig. 1 is a harmonic measuring device general structure synoptic diagram;

Fig. 2 is a DSP cellular construction synoptic diagram;

Wherein, 1-DSP unit, 2-interchange unit, 3-power supply unit, 4-open into leaving unit, 5-display unit, 6-DSP, the filtering of 7-Order RC, 8-AD, 9-frequency measurement circuit, 10-FLASH, 11-SDRAM, 12-16bit BUS, 13-PC machine;

Five, embodiment:

Below in conjunction with accompanying drawing the utility model is further specified:

See accompanying drawing 1,2, the connection of harmonic measuring device be adopt DSP unit (1) and power supply unit (3) all respectively with interchange unit (2), display unit (5), open into leaving unit (4) and be connected.It is to adopt DSP (6) to be connected with 16bit BUS (12) that the inside of DSP unit connects, and DSP (6) connects display unit (5) by HPI, and DSP (6) is connected with PC (13) by RS485, and DSP (6) is connected with frequency measurement circuit (9) by external interrupt; 16bit BUS (12) is connected with AD (8) with FLASH (10), SDRAM (11); AD (8) then is connected with Order RC filtering (7).

See accompanying drawing 1,2, in electric system, need protection and the occasion of observing and controlling under, three-phase voltage and electric current incoming transport unit (2), be converted to the voltage signal in the AD sample range after, enter the Order RC filtering and the AD passage of DSP unit (1), finish sampling; And display unit (5) is selected overtone order and other various measurement data by panel, reads the result of calculation of DSP unit (1) from the HPI interface, and is presented on the liquid crystal display.

Simulating signal is delivered to AD (8) by Order RC filtering (7), deliver to frequency measurement circuit (9) simultaneously, DSP (6) records the fundamental frequency of input signal according to external interrupt, dynamically adjust sample frequency according to this frequency values, control AD (8) and read sampled result by 16bit BUS (12), sampled result and operation result are kept at the middle DSP (6) of SDRAM (11) by HPI and display unit (5) communication, real time data is shown by display unit (5), and display unit (5) can be given DSP (6) with definite value is set by the button setting; PC (13) can read real time data by communication, also the definite value setting can be given DSP (6); DSP (6) is kept at it among FLASH (10) after checking that definite value is errorless, and the middle while of FLASH (10) is the saved system program also.

Claims (6)

1. frequency-conversion harmonic measuring device of electrical power system, comprise DSP unit (1), exchange unit (2), power supply unit (3), open, it is characterized in that into the structure of leaving unit (4) and display unit (5): its connect adopt DSP unit (1) and power supply unit (3) all respectively with interchange unit (2), display unit (5), open into leaving unit (4) and be connected; It is to adopt DSP (6) to be connected with 16bit BUS (12) that the inside of DSP unit connects, and DSP (6) connects display unit (5) by HPI, and DSP (6) is connected with PC (13) by RS485, and DSP (6) is connected with frequency measurement circuit (9) by external interrupt; 16bit BUS (12) is connected with AD (8) with FLASH (10), SDRAM (11); AD (8) then is connected with Order RC filtering (7).

2. frequency-conversion harmonic measuring device of electrical power system according to claim 1 is characterized in that: to the sampling interval of input simulating signal according to the frequency dynamic adjustment that accurately records, i.e. frequency-change sampling.

3. frequency-conversion harmonic measuring device of electrical power system according to claim 1 is characterized in that: DSP unit (1), display unit (5) have all adopted the CPU intelligent controller.

4. frequency-conversion harmonic measuring device of electrical power system according to claim 1 is characterized in that: the CPU of DSP unit (1) is the high-performance embedded dsp processor of low-cost low-power consumption.

5. frequency-conversion harmonic measuring device of electrical power system according to claim 1 is characterized in that: DSP unit (1), display unit carry out communication by the HPI interface between (5).

6. frequency-conversion harmonic measuring device of electrical power system according to claim 1 is characterized in that: power supply unit (3) has adopted Switching Power Supply.

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