CN2833607Y

CN2833607Y - Multifunctional electric energy metering instrument

Info

Publication number: CN2833607Y
Application number: CN 200520062904
Authority: CN
Inventors: 刘永强
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-08-15
Filing date: 2005-08-15
Publication date: 2006-11-01
Anticipated expiration: 2015-08-15

Abstract

The utility model relates to a multifunctional electric energy metering instrument, which is used for metering load electrical degree parameters. The multifunctional electric energy metering instrument comprises a data acquisition module, a digital signal processing module and a microprocessor module, wherein the data acquisition module is used for analog AC electrical signal acquisition and analog-to-digital conversion; the digital signal processing module is used for harmonic signal decomposition in the data acquisition module and the active and the reactive electrical degree measurement and calculation of a fundamental harmonic and the positive and the negative directions of each harmonic; the microprocessor module comprises a clock, a serial port and an LCD for displaying and controlling. The multifunctional electric energy metering instrument can accurately measure the fundamental harmonic of a supply network and the active and the reactive electrical degrees of the positive and the negative directions of each harmonic according to time intervals, and can accurately measure the reactive electrical degrees under the condition of asymmetric non-sine three-phase loads. Due to the adoption of a multi-position analog-to-digital converter, measured data is more accurate. In addition, the utility model carries out special processing for lightning protection and filtering, and avoids lightning and high-frequency interference.

Description

Multi-function power meter

Technical field

The utility model relates to a kind of electric energy metrical technology, will be referred to a kind of multi-function power meter device particularly.

Background technology

Multi-function watt-hour meter is the electric energy measuring equipment that uses electricity consumption situation in wider a kind of metering user certain hour at present.This class multi-function watt-hour meter is made up of acquisition chip and compute chip.The former gathers the ac signal of supply network according to certain frequency, and utilizes the analog-to-digital conversion device to be converted into digital signal the simulating signal that collects; The digital signal of the latter after to this conversion carried out calculation process, and then determines every index of user load institute consumed power in certain period.

Because the user power utilization loading condition is changeful, the electric current of supply network, voltage are not desirable sines all, contain a large amount of harmonic waves.These harmonic voltages, electric current become branch to user load generation meritorious and idle electric degree forward or backwards.Therefore, the electric degree that these harmonic waves of accurate measurement produce so that accurately determine power consumption, all has crucial economic implications to power supply department and user.

Existing watt-hour meter is not at first because its compositing chip itself has the function of decomposing harmonic components, therefore can't directly calculate the active power that harmonic components causes, but adopt a kind of round-about way to calculate, promptly measure the meritorious electric weight of total active electrical degree and first-harmonic, both algebraic difference is considered as the meritorious electric weight of harmonic wave.This computing method are actually a kind of rough estimation, be with the quantic addition in essence with the meritorious electric weight of each harmonic, thereby fail to distinguish meritorious electric weight of forward harmonic wave and the meritorious electric weight of reverse harmonic wave, cause the meritorious voltameter of total harmonic wave to calculate now error greatly, seriously counted the meritorious electric weight of harmonic wave less, brought loss to Utilities Electric Co.; Secondly, existing watt-hour meter adopts the idle Calculation Method of similar symmetrical sine circuit to carry out reactive measurement, can't correctly measure the idle electric degree under the asymmetric non-sinusoidal situation of three-phase, when electrical load is non-sinusoidal three-phase when asymmetric, bigger deviation can appear in the killovar-hour meter amount.

In order to address the above problem, provide a kind of multi-function power meter very necessary with the shortcoming that overcomes prior art.

The utility model content

The purpose of this utility model is to provide a kind of can accurately measure the forward and reverse meritorious multi-function power meter that reaches the idle electric degree under idle electric degree, the non-sinusoidal three-phase asymmetric load situation of harmonic wave.

The purpose of this utility model is achieved through the following technical solutions: a kind of multi-function power meter, be used to measure load electric degree parameter, it comprises analog alternating current signal sampling and analog-to-digital data acquisition module, the harmonic signal in the data acquisition module is decomposed and digital signal processor module that the positive and negative direction active electrical degree and the idle electric degree of first-harmonic, each harmonic are measured, calculated, contains the microprocessor module that clock, serial ports and LCD show control.The utility model obtains idle electric degree by instantaneous reactive power is carried out integration.

Advantage of the present utility model is: the forward and reverse meritorious and idle electric degree of first-harmonic and each harmonic in the accurate measurement supply network at times, the idle electric degree under can accurate measurement three-phase non-sinusoidal asymmetric load situation.And, owing to adopt the more analog to digital converter of numerical digit, make that the data of measuring are more accurate, in addition, add filter and lightning protection circuit in this gauge, avoided the interference of high frequency interference and thunder and lightning.

Description of drawings

Fig. 1 is the structured flowchart of the utility model multi-function power meter;

Fig. 2 is the local process flow diagram that utilizes structure shown in Figure 1 that signal is handled, in this process flow diagram, also include the photoelectrical coupler between A/D converter and digital signal processor, data buffer between digital signal processor and microprocessor and latch.

Fig. 3 is the control program process flow diagram of the microprocessor among Fig. 1.

Embodiment

Fig. 1 is the structured flowchart of the utility model multi-function power meter, as seen from the figure, this multi-function power meter comprises data acquisition module 1, digital signal processor module 2, display module 3, microprocessor module 4, multiprocessor interface module 5, communication module 6 and power module 7.

This data acquisition module 1 is used for gathering the alternating current voltage and the current analog signal of delivery network (not shown), and simulating signal is converted into digital signal.It comprises that A/C phase current sampling circuit 12, AB/CB line voltage sampling circuit 14, low pass filtered involve amplifying circuit 16, filtering zero cross detection circuit 18, A/D converter 13, phase-locked loop circuit 15 and lightning protection circuit (figure does not show).Phase current and line voltage in A/C phase current sampling circuit 12,14 pairs of supply networks of AB/CB line voltage sampling circuit are sampled, acquired signal involves amplifying circuit 16 through low pass filtered again radio-frequency component is wherein filtered, this filtering zero cross detection circuit 18 detects the zero crossing of AB/CB line voltage in sampling process, i.e. a complete voltage cycle.By A/D converter 13 simulating signal is converted into digital signal afterwards.In above-mentioned sampling process, for guaranteeing to reflect without distortion measured signal, sample frequency must be greater than the frequency of twice measured signal, consider that measured signal contains harmonic wave, when considering 32 subharmonic, sample frequency is taken as 32 * 2f (f is supply network electric voltage frequency, i.e. power frequency), i.e. sampling 64 points in the one-period.

In addition, for sample frequency can be changed from motion tracking and with the measured signal frequency change, introduced phase-locked loop circuit 15 in this data acquisition module 1, it comprises phase comparator (figure does not show), voltage controlled oscillator (figure does not show), reaches low-pass filter (figure does not show).Phase differential between these phase-locked loop circuit 15 comparator input signals and the voltage controlled oscillator output signal, thus cause that error voltage adjusts the frequency of voltage controlled oscillator, to reach output signal and input signal with frequently.

The digital signal that forms after A/D converter 13 conversions by data acquisition module 1 is carried out digital processing by digital signal processor 2.In this stage, digital signal processor 2 utilizes rapid fourier change (FFT) to voltage, and the each harmonic of electric current decomposes, and obtains first-harmonic and forward and reverse meritorious, the idle electric degree of each harmonic by instantaneous power, instantaneous reactive power being carried out integration.In the utility model, this digital signal processor 2 is comparatively common TMS320LF2407 chip.

Microprocessor module 4 is connected with display module 3, multiprocessor interface module 5, communication module 6 and real-time clock 11, and power module 7 then provides suitable operating voltage to above-mentioned each module.Handle by microprocessor module 4 again through the signal after digital signal processor 2 processing.Above-mentioned module is common realize to the positive and negative direction active electrical degree of first-harmonic, harmonic wave and idle electric degree measurement, show and and function such as external unit communication.This real-time clock 11 realized with actual time synchronously so that can realize time-sharing measurement and charge according to " peak, paddy, the flat " time of load.This display module 3 is LCD (LCD) in the utility model, is used to show load electricity consumption situation, for manual metering.This communication module 6 comprises infrared interface, RS245 interface, MODEM (modulator-demodular unit) and GPRS (GPRS (General Packet Radio Service)) four parts.Wherein infrared interface is used for being connected with meter reader, realizes the function of automatic data logging; The RS245 interface is realized carrying out communication with external unit such as computing machine; MODEM and GPRS partly are used for radio communication, and various continuous datas are sent to relevant departments.And above-mentioned various communication is duplex signaling.In an embodiment of the present utility model, this microprocessor module 4 is the PIC16F877A chip, and multiprocessor interface module 5 then is the IDT7134 chip.

Fig. 2 is the local process flow diagram that utilizes structure shown in Figure 1 that signal is handled.As seen from the figure, between the A/D converter 13 of data acquisition module 1 and digital signal processor 2, be provided with a photoelectrical coupler 8, play buffer action on the one hand, on the other hand inappropriate operating voltage is become suitable operating voltage.Be provided with data buffer 9 and latch 10 between digital signal processor 2 and the microprocessor 4.Because this multi-functional gauge is to adopt the variable period sampling, and the sampling period is determined by digital signal processor 2, so digital signal is through after the various control algolithm conversion, except entering into data buffer 9, some feeds back to A/D converter 13 and controls sampling instant outward.Simultaneously, because digital signal processor 2 there are differences with microprocessor 4 data processing speeds, in general therefore the former arithmetic speed exists the problem that data are lost easily here greater than the latter.And in this gauge, adopted data buffer 9 (in the utility model embodiment, being dual port RAM) and latch 10 for head it off, wherein the main effect of data buffer 9 is that data are stored, and the effect of latch 10 is to control from the come out sequential of data of data buffer 9, avoids taking place the sequential confusion.

Fig. 3 is the control program process flow diagram of the microprocessor among Fig. 1.At first microprocessor 4 is resetted; Secondly microprocessor 4 is postponed 0.01 second; To judge then whether the outside has the people checking meter, if any just with infrared transmission transmission data, if nobody just picks up counting in the words of checking meter, if time accumulative total reaches three minutes data that just refresh automatically in the display module, here we wait for three minutes be since usually the variation of power system load all be more slowly, if the time of refresh interval too weak point can cause display miss.Need after refreshing to wait for 0.01 second again, repeat above-mentioned process.

When total electric degree, when first-harmonic electric degree parameter is known, harmonic wave electric degree parameter just can obtain indirectly; The electric degree parameter of flat phase just can be determined after total electric degree and peak, the electric degree parameter of paddy phase are determined.Following form is the demonstration situation of display module.

Show 1: peak phase forward active electrical degree;	Show 13: maximum forward active power
Show 1: peak phase forward active electrical degree;	Show 13: maximum forward active power	Show 2: peak phase forward first-harmonic active electrical degree	Show 14: maximum reverse active power
Show 3: reverse active electrical degree of peak phase;	Show 15: the idle electric degree of forward		Show 14: maximum reverse active power
Show 3: reverse active electrical degree of peak phase;	Show 15: the idle electric degree of forward	Show 4: reverse first-harmonic active electrical degree of peak phase	Show 16: reverse idle electric degree
Show 5: paddy phase forward active electrical degree	Show 17a:ab line voltage		Show 16: reverse idle electric degree
Show 5: paddy phase forward active electrical degree	Show 17a:ab line voltage	Show 6: paddy phase forward first-harmonic active electrical degree;	Show 17b:bc line voltage
Show 7: reverse active electrical degree of paddy phase	Show 17c:ca line voltage		Show 17b:bc line voltage
Show 7: reverse active electrical degree of paddy phase	Show 17c:ca line voltage	Show 8: reverse first-harmonic active electrical degree of paddy phase	Show the 18a:a phase current
Show 9: the total active electrical degree of forward;	Show the 18b:b phase current		Show the 18a:a phase current
Show 9: the total active electrical degree of forward;	Show the 18b:b phase current	Show 10: forward first-harmonic active electrical degree;	Show the 18c:c phase current
Show 11: oppositely total active electrical degree;	Show 19: the maximum current aberration rate	Show 10: forward first-harmonic active electrical degree;	Show the 18c:c phase current
Show 11: oppositely total active electrical degree;	Show 19: the maximum current aberration rate	Show 12: reverse first-harmonic active electrical degree;	Show 20: the last power down time

Annotate: phase three-wire three tabulation meter display line voltage; Three four-wire system table meters show phase voltage

This gauge is the forward and reverse meritorious and idle electric degree of first-harmonic and each harmonic in the accurate measurement supply network at times, idle electric degree under can accurate measurement non-sinusoidal three-phase asymmetric load situation, and owing to adopt the more analog to digital converter of numerical digit, make that the data of measuring are more accurate, in addition, add filter in this gauge, avoided high frequency interference.

Claims

1. multi-function power meter, be used to measure load electric degree parameter, it is characterized in that comprising: analog alternating current signal sampling and analog-to-digital data acquisition module, be connected with this data acquisition module and the harmonic signal in the data acquisition module is decomposed and signal processor module that the positive and negative direction active electrical degree of first-harmonic, each harmonic is measured, calculated with idle electric degree, is connected and contains the microprocessor module of clock, serial ports and liquid crystal display LCD control with this signal processor module.

2. multi-function power meter as claimed in claim 1 is characterized in that: described signal processor module utilizes fast fourier transform FFT that electric current and voltage is carried out the harmonic wave decomposition.

3. multi-function power meter as claimed in claim 1 is characterized in that: idle electric degree employing is carried out integration to instantaneous reactive and is obtained.

4. multi-function power meter as claimed in claim 1 is characterized in that also comprising the display module, multiprocessor interface module, communication module and the power module that are connected with microprocessor module.

5. multi-function power meter as claimed in claim 1 is characterized in that: this data acquisition module comprises A/C phase current sampling circuit to phase current sampling, be connected with this phase current sampling circuit and to the AB/CB line voltage sampling circuit of line voltage sample, be connected with AB/CB line voltage sampling circuit and this low pass filtered to the radio-frequency component filtering in phase current, the line voltage involves amplifying circuit, filtering and zero cross detection circuit, analog to digital converter and phase-locked loop circuit, lightning protection circuit.

6. multi-function power meter as claimed in claim 2 is characterized in that: this display module is a LCD.

7. multi-function power meter as claimed in claim 2 is characterized in that: this communication module is infrared interface or RS245 interface or modem or GPRS (General Packet Radio Service) GPRS.

8. multi-function power meter as claimed in claim 1 or 2 is characterized in that: this digital signal processor module is connected with a real-time clock.

9. multi-function power meter as claimed in claim 1 or 2 is characterized in that also including the photoelectrical coupler that is connected between analog to digital converter and the digital signal processor.

10. multi-function power meter as claimed in claim 1 or 2 is characterized in that also including the data buffer and the latch that are connected between digital signal processor and the microprocessor.