CN205139241U - Three -phase harmonic optic fibre electric energy meter based on IEC62056 standard - Google Patents

Abstract

<b>The utility model relates to the technical field of power metering, which is a three-phase harmonic fiber optic energy meter based on the </b><b>IEC62056</b><b> standard, which includes a signal acquisition module, digital signal processing Module, </b><b>MCU</b><b> management unit, communication module, power supply module, the signal output terminal of the signal acquisition module is electrically connected with the signal input terminal of the digital signal processing module; the digital signal processing module The signal output terminal is electrically connected to the signal input terminal of the </b><b>MCU</b><b> management unit; the signal output terminal of the </b><b>MCU</b><b> management unit is connected to the The signal input terminals of the communication module are electrically connected. The utility model has a reasonable and compact structure and is easy to use. It can measure information such as forward and reverse fundamental harmonics, phase separation, phase combination, active and reactive power, and harmonic signal amplitude, frequency, and phase difference of each phase. A variety of events can be recorded, and the above information and events can be stored and displayed, and the three-phase harmonic fiber-optic electricity meter and information centralized center can be realized through the communication module based on the </b><b>IEC62056</b><b> standard Two-way communication between them, and then realize two-way interactive measurement with the information master station. </b>

Description

Three-phase harmonic fiber optic energy meter based on IEC62056 standard

technical field

The utility model relates to the technical field of electric power measurement, which is a three-phase harmonic optical fiber electric energy meter based on the IEC62056 standard.

Background technique

In recent years, with the growth of my country's economy, a large number of civilian electrical equipment and large-scale industrial electrical equipment have been used, which has brought a lot of pollution to the power grid. The harmonic part introduced into the power grid has become an important parameter that cannot be ignored for evaluating the quality of the power grid and for measuring electric energy. Conventional energy metering chips used in traditional methods are difficult to meet today's needs in terms of sampling rate, computing speed, and accuracy. At the same time, algorithms for three-phase electrical harmonic signals are emerging one after another, with higher accuracy and embedded algorithms that are easier to implement, and are more and more accepted by people. Therefore, the design of the new three-phase harmonic energy meter is in a state of rapid development. The IEC62056 standard is the only data exchange standard in the world about electric energy measurement, meter reading, tariff and load control. However, as a relatively advanced and mature standard internationally, the IEC62056 standard is still rarely used in China. Considering its many advantages, the application of the IEC62056 standard will be an important issue. In recent years, power metering systems have become more and more dependent on modern communication technology, and communication technology has always been one of the industry's research priorities. At present, the transmission methods commonly used in my country's market mainly include RS485, low-voltage power line carrier communication technology PLC (Programmable Logic Controller, programmable controller), wireless communication and optical fiber communication. Among them, the RS485 field wiring is relatively complicated, the PLC method has poor information transmission accuracy due to high attenuation, low impedance, harmonic interference and other reasons, and the wireless communication transmission rate is generally slow, so it has fast transmission rate, long transmission distance and anti-interference ability The optical fiber communication method with strong and other advantages is very suitable for application in power metering systems.

Contents of the invention

The utility model provides a three-phase harmonic optical fiber electric energy meter based on the IEC62056 standard, which overcomes the above-mentioned deficiencies in the prior art, and can effectively solve the difficulty in meeting the requirements of the existing electric energy metering chips in terms of sampling rate, operation speed and precision. problems, and the RS485 field wiring in the existing transmission mode is relatively complicated, the information transmission accuracy of the PLC mode is poor due to reasons such as high attenuation, low impedance, and harmonic interference, and the transmission rate of wireless communication is generally slow.

The technical scheme of the utility model is realized through the following measures: a three-phase harmonic fiber optic electric energy meter based on the IEC62056 standard, including a signal acquisition module, a digital signal processing module, an MCU (Main Computational Unit, main computing component) management unit, a communication module, power supply module, and the signal output end of the signal acquisition module are electrically connected to the signal input end of the digital signal processing module; the signal output end of the digital signal processing module is electrically connected to the signal input end of the MCU management unit; the signal output end of the MCU management unit It is electrically connected to the signal input terminal of the communication module; the signal acquisition module, the digital signal processing module, the MCU management unit, and the communication module are respectively electrically connected to the power supply module.

Below is the further optimization or/and improvement to above-mentioned utility model technical scheme:

The above-mentioned signal acquisition module includes a voltage sampling circuit, a current sampling circuit, and an analog-to-digital conversion circuit. The two input ends are electrically connected, and the output end of the analog-to-digital conversion circuit is electrically connected to the input end of the digital signal processing module.

Above-mentioned digital signal processing module comprises data processing chip DSP (digitalsignalprocessing, digital signal processing), and data processing chip DSP comprises EMIFB (ExternalMemoryInterfaceB, B class external memory interface) module and MCBSB module, and EMIFB module is externally expanded with SDRAM (SynchronousDynamicRandomAccessMemory, synchronous dynamic random memory), and the EMIFB module is externally connected to a serial Flash (flash memory) chip.

Above-mentioned MCU management unit comprises: the MCU module that can receive the data from data processing chip DSP; Can the LCD (LiquidCrystalDisplay, liquid crystal display) display that the data received come out; Can input the keyboard of order to MCU module; External read-write USB (Universal Serial Bus, Universal Serial Bus) module; EEPROM (Electrically Erasable Programmable Read-Only Memory, Electrically Erasable Programmable Read-Only Memory) capable of storing parameter information and saving internal data.

The above-mentioned communication module is an optical fiber communication module.

The utility model has a reasonable and compact structure and is easy to use. It adopts the structure of signal acquisition module + digital signal processing module + MCU management unit + communication module, and can measure forward and reverse fundamental harmonics, phase separation, phase combination, and active power. , reactive power, and harmonic signal amplitude, frequency, phase difference and other information of each phase, can record a variety of events, and can store and display the above information and events, and realize three-phase harmonics through the communication module based on IEC62056 standard The two-way communication between the fiber-optic meter and the information centralized center, and then realize the two-way interactive measurement with the information master station, which overcomes the complicated field wiring of RS485 and the accuracy of information transmission due to high attenuation, low impedance, harmonic interference and other reasons in PLC mode It has the characteristics of poor reliability and generally slow wireless communication transmission rate, which is safe, labor-saving, simple and efficient.

Description of drawings

Accompanying drawing 1 is the structural block diagram of the preferred embodiment of the present utility model.

Accompanying drawing 2 is the algorithm flow chart of the digital signal processing module in the preferred embodiment of the utility model.

Accompanying drawing 3 is the A-phase voltage conditioning circuit diagram in the best embodiment of the utility model.

Accompanying drawing 4 is the circuit diagram of A-phase current conditioning in the best embodiment of the utility model.

Accompanying drawing 5 is the circuit diagram of sampling module in the utility model preferred embodiment.

Accompanying drawing 6 is the circuit diagram of data processing chip DSP in the utility model preferred embodiment.

Accompanying drawing 7 is the interface circuit diagram of SDRAM in the utility model preferred embodiment.

Accompanying drawing 8 is the interface circuit diagram of serial Flash chip in the utility model preferred embodiment.

Accompanying drawing 9 is the circuit diagram of LCD display in the utility model preferred embodiment.

Accompanying drawing 10 is the interface circuit diagram of USB module in the utility model preferred embodiment.

Accompanying drawing 11 is the circuit diagram of EEPROM in the utility model preferred embodiment.

Accompanying drawing 12 is the circuit diagram of the optical fiber communication module in the preferred embodiment of the utility model.

The codes in the drawings are: 1 is the signal acquisition module, 2 is the digital signal processing module, 3 is the MCU management unit, 4 is the communication module, 5 is the voltage sampling circuit, 6 is the current sampling circuit, 7 is the analog-to-digital conversion circuit , 8 is a data processing chip DSP, 9 is SDRAM, 10 is a serial Flash chip, 11 is an MCU module, 12 is an LCD display, 13 is a keyboard, 14 is a USB module, 15 is EEPROM, I is a three-phase current, U is three-phase voltage.

detailed description

The utility model is not limited by the following examples, and the specific implementation manner can be determined according to the technical scheme 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, the three-phase harmonic fiber optic energy meter based on the IEC62056 standard includes a signal acquisition module 1, a digital signal processing module 2, an MCU management unit 3, a communication module 4, a power supply module, and the signal output of the signal acquisition module 1 end is electrically connected to the signal input end of the digital signal processing module 2; the signal output end of the digital signal processing module 2 is electrically connected to the signal input end of the MCU management unit 3; the signal output end of the MCU management unit 3 is connected to the signal input of the communication module 4 The terminals are electrically connected; the signal acquisition module 1, the digital signal processing module 2, the MCU management unit 3, and the communication module 4 are respectively electrically connected to the power supply module. The utility model adopts the architecture of signal acquisition module + digital signal processing module + MCU management unit + communication module, which can measure forward and reverse fundamental harmonics, phase separation, phase combination, active and reactive power and harmonics of each phase Signal amplitude, frequency, phase difference and other information can record a variety of events, and can store and display the above information and events, through the communication module 4 based on the IEC62056 standard to realize the communication between the three-phase harmonic fiber optic meter and the information centralized center Two-way communication, and then realize two-way interactive measurement with the information master station, overcome the complexity of RS485 field wiring, the PLC method has poor information transmission accuracy due to reasons such as high attenuation, low impedance, harmonic interference, and wireless communication transmission. The problem of generally slow speed.

According to actual needs, the above-mentioned three-phase harmonic fiber optic energy meter based on IEC62056 standard can be further optimized or/and improved:

As shown in accompanying drawing 1, above-mentioned signal acquisition module 1 comprises voltage sampling circuit 5, current sampling circuit 6, analog-to-digital conversion circuit 7, the output end of voltage sampling circuit 5 is electrically connected with the first input end of analog-to-digital conversion circuit 7, The output terminal of the current sampling circuit 6 is electrically connected to the second input terminal of the analog-to-digital conversion circuit 7 , and the output terminal of the analog-to-digital conversion circuit 7 is electrically connected to the input terminal of the digital signal processing module 2 . Signal acquisition module 1 mainly includes three parts: voltage sampling circuit 5, current sampling circuit 6, and analog-to-digital conversion circuit 7. The sampling chip of signal acquisition module 1 uses a 6-channel 16-bit high-speed, high-precision synchronous analog-to-digital conversion Chip ADS8556, voltage sampling circuit 5, and current sampling circuit 6 are composed of current-limiting resistors, sampling resistors, high-precision voltage transformers, high-precision current transformers, operational amplifiers, limiting diodes, and low-pass filters. 1 Accurate sampling and conversion of three-phase electrical signals can be realized.

As shown in accompanying drawing 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 is externally expanded with SDRAM9, and EMIFB module is externally connected serial Flash chip 10. The digital signal processing module 2 mainly includes a data processing chip DSP8, the model is TMS320C6745 floating-point DSP, and the data processing chip DSP8 has an MCBSP module, which can realize SPI communication with the signal acquisition module 1 and the MCU management unit 3, and the implementation method is relatively simple. The data processing chip DSP8 has a very strong digital computing ability, and can perform a large amount of data computing in a very short time. Through the EMIFB module of the data processing chip DSP8, the SDRAM9 can be expanded externally, and at the same time, the serial Flash chip 10 is externally connected to the Operational data and programs are stored. At the same time, the design of the utility model adopts the bispectral line interpolation FFT harmonic analysis algorithm based on the KN interconvolution window, through which the algorithm can effectively overcome the influence of the fundamental frequency fluctuation and white noise on the harmonic analysis. When the test signal is truncated with a non-integer period, the relative error of the phase detection of the fundamental wave and each harmonic of the signal is <5×10 ^-5 %, and the relative error of the amplitude detection is <9×10 ^-9 %. In turn, accurate measurement of various parameters of the signal can be realized.

As shown in accompanying drawing 1, above-mentioned MCU management unit 3 comprises: the MCU module 11 that can receive the data from data processing chip DSP8; 13; a USB module 14 capable of external reading and writing of data; an EEPROM 15 capable of storing parameter information and saving internal data. The core management chip of the MCU management unit 3 of the three-phase harmonic fiber-optic energy meter based on the IEC62056 standard adopts MK60DN512VLQ10, which is responsible for receiving data from the data processing chip DSP8, and displays the data on the LCD display 12 of the three-phase harmonic energy meter. Moreover, the data can be sent to the master station through the optical fiber communication method based on the IEC62056 communication protocol, and at the same time, the instructions sent by the master station can also be accepted; in addition, the MCU management unit 3 expands the button module to access the general IO port of the chip, which can be accessed through the keyboard 13 Write the terminal service program and respond to the user's key operation in real time; the USB module 14 can realize the external reading of data, and can read the data into the U disk; the EEPROM 15 can store various parameter information while internally saving data.

As shown in FIG. 1 , the above-mentioned communication module 4 is an optical fiber communication module. Optical fiber has the characteristics of large communication capacity, long transmission distance, small signal interference, and good confidentiality performance.

The above technical features constitute the best embodiment of the utility model, which has strong adaptability and best implementation effect, and non-essential technical features can be increased or decreased according to actual needs to meet the needs of different situations.

The use process of the most preferred embodiment of the utility model:

As the core of data processing, the data processing chip DSP8 will receive the digital signal sampled from the signal acquisition module 1, and then use the bispectral interpolation FFT harmonic analysis algorithm based on the K-N interconvolution window inside the data processing chip DSP8 to obtain the sampled signal. The amplitude A, frequency f and phase angle φ of the signal, as shown in Figure 2, can be carried out according to the following steps:

Step 101, signal interception to obtain a sampling sequence;

Step 102, using K-N inter-convolution window weighting to obtain a new sequence;

Step 103, performing discrete Fourier transform to obtain discrete frequency spectrum X(k);

Step 104, finding the largest spectral line K1 and the next largest spectral line K2;

Step 105, calculating ratio coefficients β and α;

Step 106, the function α=g(β) of α about β can be obtained from the spectrum function;

Step 107, α is obtained by least square method;

In step 108, the frequency f _h , amplitude A _h , and phase angle φ _h of the hth harmonic are obtained through α.

Specifically:

First, select the sampling length N and sampling frequency f _s , intercept the sampled discrete signal to obtain a sampling sequence, and use the KN interconvolution window to weight the sequence to obtain a new sequence;

Then, the discrete Fourier transform is performed on it to obtain the discrete spectrum Find the largest spectral line k ₁ and the second largest spectral line k ₂ near the peak point k of frequency f _N in the discrete spectrum, and the corresponding spectral amplitudes are │X _w (k ₁ )│ and │X _w (k ₂ )│, At the same time, the following parameters are specified α=kk ₁ -0.5, that is, the value range of α is [-0.5,0.5], which can be obtained from the expression of X _w (k)

Finally, the value of α is calculated by the least squares polynomial approximation method, and then the hth harmonic frequency is obtained into the entire calculation process of the algorithm.

As shown in Figure 3, the three-phase harmonic fiber optic energy meter based on the IEC62056 standard uses high-precision voltage transformers and high-precision current transformers for three-phase voltage and current sampling, and uses I-V conversion circuits. Specifically as shown in accompanying drawings 3 and 4. Among them, accompanying drawing 3 and accompanying drawing 4 are the voltage of phase A in the three-phase electricity, and R4 and R5 in the current conditioning circuit convert the voltage signal into a current signal; PT is a current-type voltage transformer of 2mA/2mA; PT secondary side The current signal passes through the I-V conversion circuit, in which R1 and C2 are connected in parallel to compensate its phase; C4, C5, and R6 form a low-pass filter, which can effectively filter out the high-frequency part of the sampling signal and reduce spectrum aliasing; The function of D1 and D2 is to prevent some high-frequency signals on the secondary side of the transformer from generating a large voltage after passing through the coil. When the voltage is greater than the conduction voltage of D1 and D2, D1 or D2 conducts to play the role of clamping protection. Accompanying drawing 4 is a current signal conditioning circuit, and its working principle is basically consistent with accompanying drawing 3. The signal conditioning circuit of the two-phase voltage and current of B and C is consistent with the parameters of the circuit.

As shown in Figure 5, the three-phase electrical voltage and current signals after signal conditioning are sampled by the ADC, and the sampling rate of the ADC is controlled by the data processing chip DSP. The utility model sets the HW/SW pin of the ADC to high level through the data processing chip DSP to make it work in the software mode. The CONVST_A, CONVST_B, and CONVST_C pins of the chip are connected in parallel, and then connected to the PWM output of the DSP.

As shown in accompanying drawings 6, 7, and 8, the core chip in the digital signal processing module adopts a floating-point data processing chip DSP, and the model is TMS320C6745. Accompanying drawing 6 is the minimum system circuit diagram of the chip, including the power management and reset circuit composed of MAX708S, the clock circuit adopts active crystal oscillator, JTAG circuit and filter circuit. MT48LC16M16A2 chip is selected for external expansion SDRAM, and the circuit connection is shown in Figure 7. SST25F016B chip is selected as the external Flash, and the circuit connection is shown in Figure 8. Both of them communicate with the data processing chip DSP through SPI.

As shown in accompanying drawings 9, 10, and 11, the core management chip of the MCU management unit adopts the MK60DN512VLQ10 chip, and the main functional modules of the entire management unit include LCD display, USB module and EEPRPM storage circuit. Among them, the LCD display adopts the serial port transmission mode, and communicates with the LCD through the UART port of MK60DN512VLQ10. MK60DN512VLQ10 supports the OTG function of the USB2.0 interface, so that the two USB peripherals can directly transmit data without being separated from the PC. Attachment 10 is the interface circuit diagram. The power switch chip MIC2026 can provide 5V external voltage when using the OTG function.

As shown in Figure 12, the optical fiber communication module is mainly composed of an IEC62056 standard protocol stack, a communication port, an application process module and a logic device unit. The optical fiber communication protocol in the design refers to the IEC62056 standard, including the physical device driver, logical connection management, application layer encoding and decoding, and data link layer frame assembly and analysis for the communication of the master station of the system, which constitutes the standard communication interface of the master station; the communication port part Provide the driver of the physical medium or communication mode of the harmonic meter optical fiber for communication, and provide the communication channel; the application process module completes the data management, event reporting and management of the three-phase harmonic energy meter through the coordination of each logical device in the logical unit Work. At the same time, the energy meter and the master station are managed through the scheduling of the communication protocol stack; in the IEC6256 standard protocol, the logical device unit is composed of several logical devices, and each logical device is composed of several COMSEM interface objects, through several different COSEM objects cooperate with each other to complete a specific function.

The above technical features constitute the best embodiment of the utility model, which has strong adaptability and best implementation effect, and non-essential technical features can be increased or decreased according to actual needs to meet the needs of different situations.

Claims (9)

1. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard, it is characterized in that comprising signal acquisition module, digital signal processing module, MCU 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.

2. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard according to claim 1, it is characterized in that 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.

3. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard according to claim 1 and 2, it is characterized in that digital signal processing module comprises data processing chip DSP, data processing chip DSP comprises EMIFB module and MCBSB module, EMIFB module has extended out SDRAM, the external serial Flash chip of EMIFB module.

4. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard according to claim 1 and 2, is characterized in that MCU administrative unit comprises: the MCU module that can receive the data from data processing chip DSP; The LCD display that the data received can be shown; The keyboard of instruction can be inputted to MCU module; The USB module of the exterior read-write of data can be realized; Can parameter information and the EEPROM preserving internal data.

5. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard according to claim 3, is characterized in that MCU administrative unit comprises: the MCU module that can receive the data from data processing chip DSP; The LCD display that the data received can be shown; The keyboard of instruction can be inputted to MCU module; The USB module of the exterior read-write of data can be realized; Can parameter information and the EEPROM preserving internal data.

6. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard according to claim 1 and 2, is characterized in that communication module is fiber optic telecommunications module.

7. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard according to claim 3, is characterized in that communication module is fiber optic telecommunications module.

8. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard according to claim 4, is characterized in that communication module is fiber optic telecommunications module.

9. the three phase harmonic optical fiber electric energy meter based on IEC62056 standard according to claim 5, is characterized in that communication module is fiber optic telecommunications module.