Summary of the invention
The utility model provides a kind of three phase harmonic optical fiber electric energy meter based on IEC62056 standard, overcome the deficiency of above-mentioned prior art, it effectively can solve sampling rate that existing electric energy computation chip exists, arithmetic speed, precision be difficult to the problem that satisfies the demands, and RS485 field wiring is comparatively complicated in existing transmission mode, PLC mode is poor because the cause informations such as height decay, Low ESR, humorous wave interference transmit accuracy, the general slower problem of wireless communication transmissions speed.
The technical solution of the utility model is realized by following measures: a kind of three phase harmonic optical fiber electric energy meter based on IEC62056 standard, comprise signal acquisition module, digital signal processing module, MCU (MainComputationalUnit, main calculating unit) administrative unit, communication module, power module, the signal output part of signal acquisition module is electrically connected with the signal input part of digital signal processing module; The signal output part of digital signal processing module is electrically connected with the signal input part of MCU administrative unit; The signal output part of MCU administrative unit is electrically connected with the signal input part of communication module; Signal acquisition module, digital signal processing module, MCU administrative unit, communication module are electrically connected with power module respectively.
Here is the further optimization and/or improvements to above-mentioned utility model technical scheme:
Above-mentioned signal acquisition module comprises voltage sampling circuit, current sampling circuit, analog to digital conversion circuit, the output terminal of voltage sampling circuit is electrically connected with the first input end of analog to digital conversion circuit, the output terminal of current sampling circuit is electrically connected with the second input end of analog to digital conversion circuit, and the output terminal of analog to digital conversion circuit is electrically connected with the input end of digital signal processing module.
Above-mentioned digital signal processing module comprises data processing chip DSP (digitalsignalprocessing, digital signal processing), data processing chip DSP comprises EMIFB (ExternalMemoryInterfaceB, category-B external memory interface) module and MCBSB module, EMIFB module has extended out SDRAM (SynchronousDynamicRandomAccessMemory, synchronous DRAM), the external serial Flash of EMIFB module (flash memory) chip.
Above-mentioned MCU administrative unit comprises: the MCU module that can receive the data from data processing chip DSP; LCD (LiquidCrystalDisplay, the liquid crystal display) display that the data received can be shown; The keyboard of instruction can be inputted to MCU module; USB (UniversalSerialBus, the USB (universal serial bus)) module of the exterior read-write of data can be realized; Can parameter information and the EEPROM (ElectricallyErasableProgrammableRead-OnlyMemory, EEPROM (Electrically Erasable Programmable Read Only Memo)) preserving internal data.
Above-mentioned communication module is fiber optic telecommunications module.
The utility model reasonable and compact in structure, easy to use, which employs the framework of signal acquisition module+digital signal processing module+MCU administrative unit+communication module, forward can be measured, reverse fundamental, phase-splitting, close phase, meritorious, reactive power and each phase harmonic signal amplitude, frequency, the information such as phase differential, multiple event can be recorded, and can store above-mentioned information and event and show, two-way communication between center is concentrated by realizing three phase harmonic Optical fiber electricity meter and information based on the communication module of IEC62056 standard, and then the two-way interaction realized between information main website is measured, overcome RS485 field wiring comparatively complicated, PLC mode decays due to height, Low ESR, the cause information transmission accuracys such as humorous wave interference are poor, wireless communication transmissions is the general slower problem of speed again, there is safety, laborsaving, easy, efficient feature.
Accompanying drawing explanation
Accompanying drawing 1 is the structured flowchart of the utility model most preferred embodiment.
Accompanying drawing 2 is the algorithm flow chart of digital signal processing module in the utility model most preferred embodiment.
Accompanying drawing 3 is A phase voltage modulate circuit figure in the utility model most preferred embodiment.
Accompanying drawing 4 is A phase current modulate circuit figure in the utility model most preferred embodiment.
Accompanying drawing 5 is the circuit diagram of sampling module in the utility model most preferred embodiment.
Accompanying drawing 6 is the circuit diagram of data processing chip DSP in the utility model most preferred embodiment.
Accompanying drawing 7 is the interface circuit figure of SDRAM in the utility model most preferred embodiment.
Accompanying drawing 8 is the interface circuit figure of serial Flash chip in the utility model most preferred embodiment.
Accompanying drawing 9 is the circuit diagram of LCD display in the utility model most preferred embodiment.
Accompanying drawing 10 is the interface circuit figure of USB module in the utility model most preferred embodiment.
Accompanying drawing 11 is the circuit diagram of EEPROM in the utility model most preferred embodiment.
Accompanying drawing 12 is the circuit diagram of fiber optic telecommunications module in the utility model most preferred embodiment.
Coding in accompanying drawing is respectively: 1 is signal acquisition module, and 2 is digital signal processing module, and 3 is MCU administrative unit, 4 is communication module, and 5 is voltage sampling circuit, and 6 is current sampling circuit, 7 is analog to digital conversion circuit, and 8 is data processing chip DSP, and 9 is SDRAM, 10 is serial Flash chip, and 11 is MCU module, and 12 is LCD display, 13 is keyboard, and 14 is USB module, and 15 is EEPROM, I is three-phase current, and U is three-phase voltage.
Embodiment
The utility model by the restriction of following embodiment, can not determine concrete embodiment according to the technical solution of the utility model and actual conditions.
Below in conjunction with embodiment and accompanying drawing, the utility model is further described:
As shown in Figure 1, should comprise signal acquisition module 1, digital signal processing module 2, MCU administrative unit 3, communication module 4, power module based on the three phase harmonic optical fiber electric energy meter of IEC62056 standard, the signal output part of signal acquisition module 1 is electrically connected with the signal input part of digital signal processing module 2; The signal output part of digital signal processing module 2 is electrically connected with the signal input part of MCU administrative unit 3; The signal output part of MCU administrative unit 3 is electrically connected with the signal input part of communication module 4; Signal acquisition module 1, digital signal processing module 2, MCU administrative unit 3, communication module 4 are electrically connected with power module respectively.The utility model have employed the framework of signal acquisition module+digital signal processing module+MCU administrative unit+communication module, forward can be measured, reverse fundamental, phase-splitting, close phase, meritorious, reactive power and each phase harmonic signal amplitude, frequency, the information such as phase differential, multiple event can be recorded, and can store above-mentioned information and event and show, two-way communication between center is concentrated by realizing three phase harmonic Optical fiber electricity meter and information based on the communication module 4 of IEC62056 standard, and then the two-way interaction realized between information main website is measured, overcome RS485 field wiring comparatively complicated, PLC mode decays due to height, Low ESR, the cause information transmission accuracys such as humorous wave interference are poor, wireless communication transmissions is the general slower problem of speed again.
According to actual needs, the above-mentioned three phase harmonic optical fiber electric energy meter based on IEC62056 standard can be made further optimization and/or improvements:
As shown in Figure 1, above-mentioned signal acquisition module 1 comprises voltage sampling circuit 5, current sampling circuit 6, analog to digital conversion circuit 7, the output terminal of voltage sampling circuit 5 is electrically connected with the first input end of analog to digital conversion circuit 7, the output terminal of current sampling circuit 6 is electrically connected with the second input end of analog to digital conversion circuit 7, and the output terminal of analog to digital conversion circuit 7 is electrically connected with the input end of digital signal processing module 2.Signal acquisition module 1 mainly comprises voltage sampling circuit 5, current sampling circuit 6, analog to digital conversion circuit 7 three part, wherein the sampling A/D chip of signal acquisition module 1 employs high speed, the high-precise synchronization modulus conversion chip ADS8556 of a 16,6 passage, the composition of voltage sampling circuit 5, current sampling circuit 6 comprises current-limiting resistance, sampling resistor, high-accuracy voltage mutual inductor, high precision current transformer, operational amplifier, limiter diode, low-pass filter, can be realized accurate sampling and the conversion of three-phase electricity signal by signal acquisition module 1.
As shown in Figure 1, above-mentioned digital signal processing module 2 comprises data processing chip DSP8, and data processing chip DSP8 comprises EMIFB module and MCBSB module, and EMIFB module has extended out SDRAM9, the external serial Flash chip 10 of EMIFB module.Digital signal processing module 2 mainly comprises data processing chip DSP8, model is TMS320C6745 floating type DSP, data processing chip DSP8 has MCBSP module, and can realize the SPI communication with signal acquisition module 1, MCU administrative unit 3, implementation is comparatively simple.Data processing chip DSP8 has extremely strong digital operating ability, a large amount of data operations can be performed in very short time, can expand SDRAM9 outward by the EMIFB module of data processing chip DSP8, external serial Flash chip 10, is respectively used to store operational data and program simultaneously.Simultaneously, the utility model designs, have employed the double spectral line interpolation FFT algorithm of harmonics analysis based on the mutual convolution window of K-N, the impact that fundamental frequency fluctuates and white noise produces frequency analysis effectively can be overcome by this algorithm, and when carrying out non-integer to test signal and blocking, to the first-harmonic of signal and equal <5 × 10 of phase-detection relative error of each harmonic
-5%, equal <9 × 10 of amplitude detection relative error
-9%.And then can realize signal parameters Measurement accuracy.
As shown in Figure 1, above-mentioned MCU administrative unit 3 comprises: can receive the MCU module 11 from the data of data processing chip DSP8; The LCD display 12 that the data received can be shown; The keyboard 13 of instruction can be inputted to MCU module 11; The USB module 14 of the exterior read-write of data can be realized; Can parameter information and the EEPROM15 preserving internal data.Hard core control chip based on the MCU administrative unit 3 of the three phase harmonic optical fiber electric energy meter of IEC62056 standard adopts MK60DN512VLQ10, be responsible for receiving the data from data processing chip DSP8, data are shown in the LCD display 12 of three phase harmonic electric energy meter, and send the data to main website by the optical fiber communication mode based on IEC62056 communication protocol, also can accept the instruction that main website sends simultaneously; In addition, MCU administrative unit 3 extends key-press module access chip universal I/O port, writes terminal server by keyboard 13, and real-time response user key-press operates; The outside that USB module 14 can realize data is read, and data can be read into USB flash disk inside; EEPROM15 can store various parameter information, inner preservation data.
As shown in Figure 1, above-mentioned communication module 4 is fiber optic telecommunications module.Optical fiber has the advantages that message capacity is large, long transmission distance, signal disturbing are little, security performance is good.
Above technical characteristic constitutes most preferred embodiment of the present utility model, and it has stronger adaptability and best implementation result, can increase and decrease non-essential technical characteristic according to actual needs, meet the demand of different situations.
The use procedure of the utility model most preferred embodiment:
Data processing chip DSP8 as the core of data processing can receive and sample the digital signal obtained from signal acquisition module 1, then the amplitude A of sampled signal, frequency f and angle phi is obtained by the double spectral line interpolation FFT algorithm of harmonics analysis based on the mutual convolution window of K-N of data processing chip DSP8 inside, as shown in Figure 2, can perform according to following step:
Step 101, signal intercepts and obtains sample sequence;
Step 102, adopts the mutual convolution window weighting process of K-N, obtains new sequence;
Step 103, carries out discrete Fourier transformation, obtains discrete spectrum X (k);
Step 104, finds maximum spectral line K1 and secondary large spectral line K2;
Step 105, ratio calculated factor beta and α;
Step 106, can obtain the function alpha=g (β) of α about β by frequency spectrum function;
Step 107, just goes out α by least square method;
Step 108, obtains the frequency f of h subharmonic by α
h, amplitude A
h, angle phi
h.
Be specially:
First, sampling length N and sample frequency f is chosen
s, sample variance signal is intercepted, obtains sample sequence, adopt the mutual convolution window of K-N to sequence weighting process, obtain new sequence;
Then, discrete Fourier transformation is carried out to it and obtain discrete spectrum
find discrete spectrum medium frequency f
nthe maximum spectral line k of amplitude near peak point k
1and secondary large spectral line k
2, corresponding spectrum amplitude is respectively │ X
w(k
1) │ and │ X
w(k
2) │, meanwhile, provide as follows parameter
α=k-k
1-0.5, i.e. α span [-0.5,0.5], by X
wk the expression formula of () can obtain
Finally, calculate the value of α with least square polynomial approximation method, and then obtain h subfrequency
become whole algorithm computation process.
As shown in Figure 3, should based on the three phase harmonic optical fiber electric energy meter of IEC62056 standard, its three-phase voltage, current sample have employed high-accuracy voltage mutual inductor and high precision current transformer, and adopt the mode of I-V change-over circuit.Specifically as shown in accompanying drawing 3,4.Wherein accompanying drawing 3 and accompanying drawing 4 are the voltage of A phase in three-phase electricity respectively, voltage signal is converted into current signal by R4 and R5 in current regulating circuit; PT is the current mode voltage transformer (VT) of 2mA/2mA; PT secondary side current signal is through I-V change-over circuit, and wherein R1 and C2 in parallel is to compensate its phase place; C4, C5, R6 constitute low-pass filter device, can HFS in effectively filtering sampled signal, reduce spectral aliasing; The effect of D1 and D2 is to prevent some high-frequency signal of mutual inductor secondary side from producing large voltage after coil, and when voltage is greater than D1 and D2 forward voltage, D1 or D2 conducting, plays the effect of clamped protection.Accompanying drawing 4 is current signal conditioning circuit, its principle of work and accompanying drawing 3 basically identical.The signal conditioning circuit of B, C two phase voltage, electric current is consistent with this circuit parameter.
As shown in Figure 5, the three-phase electricity voltage after signal condition, current signal are sampled by ADC, by the sampling rate of data processing chip DSP control ADC.The HW/SW pin of ADC is set to high level by data processing chip DSP by the utility model, makes it to be operated in software pattern.CONVST_A, CONVST_B, CONVST_C tri-pins in parallel of chip, are then connected with the PWM output terminal of DSP.
As shown in accompanying drawing 6,7,8, in digital signal processing module, acp chip adopts real-coded GA process chip DSP, and model is TMS320C6745.Accompanying drawing 6 is the minimum system circuit diagram of this chip, and comprise power management and the reset circuit of MAX708S formation, clock circuit adopts active crystal oscillator, jtag circuit and filtering circuit.Extend out SDRAM and select MT48LC16M16A2 chip, circuit connects as shown in Figure 7.External Flash selects SST25F016B chip, and circuit connects as shown in Figure 8.Both are all communicated by the mode of SPI with between data processing chip DSP.
As shown in accompanying drawing 9,10,11, the hard core control chip of MCU administrative unit adopts MK60DN512VLQ10 chip, and the main functional modules of whole administrative unit comprises LCD display, USB module and EEPRPM memory circuit and forms.Wherein LCD display adopts Serial Port Transmission mode, is communicated with LCD by the UART mouth of MK60DN512VLQ10.MK60DN512VLQ10 supports the OTG function of USB2.0 interface, and make 2 USB peripheral hardwares directly can transmit data in the situation departing from PC, accompanying drawing 10 is its interface circuit figure, and power switch chip MIC2026 can externally provide 5V voltage when using OTG function.
As shown in Figure 12, fiber optic telecommunications module forms primarily of IEC62056 standard protocol stack, communication port, application process module and logical device unit.In design, optical-fibre communications agreement is with reference to IEC62056 standard, comprises physical equipment drivings to the end communication of system main website, logic connection management, the assembling of application layer encoding and decoding and data link layer frame and parsing, formation main website standard communication interface; PORT COM part provides the physical medium of harmonic meter optical fiber for communication or the driving of communication modes, provides communication channel; Application process module is by completing the data management of three phase harmonic electric energy meter, event report and management work to the coordination of logical device each in logical block.Simultaneously by managing electric energy meter and main website to the scheduling of communication protocol stack; In IEC6256 standard agreement, logical device unit is made up of several logical device, and each logical device is made up of several COMSEM interface class objects again, have been cooperatively interacted certain specific function by some different COSEM objects.
Above technical characteristic constitutes most preferred embodiment of the present utility model, and it has stronger adaptability and best implementation result, can increase and decrease non-essential technical characteristic according to actual needs, meet the demand of different situations.