CN210181119U - Three-phase voltage monitoring system - Google Patents

Abstract

The utility model discloses a three-phase voltage monitoring system, which comprises a MCU, a power module, a sampling module and a display module; the power supply module, the sampling module and the display module are all connected with the MCU; the power supply module is used for supplying power to the MCU; the sampling module comprises a voltage transformer, an amplifying circuit and a reference voltage circuit; the number of the voltage transformers is 3, and the voltage transformers are used for respectively acquiring three-phase voltage signals; the amplifying circuit is based on the operational amplifier, the reference voltage circuit provides reference voltage for the operational amplifier, the number of the amplifying circuits is 3, the amplifying circuits are respectively connected with the output ends of 3 voltage transformers, and the output ends of the 3 amplifying circuits are connected with 3 ADC ports of the MCU. The three-phase voltage monitoring system is easy to implement.

Description

Three-phase voltage monitoring system

Technical Field

The utility model relates to a three-phase voltage monitoring system.

Background

Under the background that the human society enters the knowledge and economy era and the information technology is developed at a high speed, the electric power instrument and the measurement control technology thereof are also widely applied day by day, and a good opportunity is provided for the rapid development of the instrument industry. In terms of measurement accuracy, the difference between the existing domestic products and the foreign products is generally 1 order of magnitude.

Therefore, it is necessary to design a three-phase voltage monitoring system.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a three-phase voltage monitoring system is provided, this three-phase voltage monitoring system easy to carry out.

The technical solution of the utility model is as follows:

a three-phase voltage detection system comprises an MCU (microprogrammed control Unit), a power supply module, a sampling module and a display module;

the power supply module, the sampling module and the display module are all connected with the MCU;

the power supply module is used for supplying power to the MCU;

the sampling module comprises a voltage transformer, an amplifying circuit and a reference voltage circuit; the number of the voltage transformers is 3, and the voltage transformers are used for respectively acquiring three-phase voltage signals; the amplifying circuit is based on the operational amplifier, the reference voltage circuit provides reference voltage for the operational amplifier, the number of the amplifying circuits is 3, the amplifying circuits are respectively connected with the output ends of 3 voltage transformers, and the output ends of the 3 amplifying circuits are connected with 3 ADC ports of the MCU.

The reference voltage circuit provides a reference voltage of 1.1V for the operational amplifier.

The reference voltage circuit further includes an operational amplifier based voltage follower.

The output end of the reference voltage circuit is respectively connected with the inverting input ends of the operational amplifiers of the 3 amplifying circuits through resistors R7-R9;

the non-inverting input ends of the operational amplifiers of the 3 amplifying circuits are respectively connected with 3 voltage transformers;

a resistor is connected between the inverting input end and the output end of each operational amplifier in a bridging manner, and 3 resistors are respectively R10, R11 and R12; the output ends of the operational amplifiers of the 3 amplifying circuits are respectively connected with 3 ADC ports of the MUC.

And R10, R11 and R12 are all 10K ohms, and R7-R9 are all 10K ohms, so that through calculation, Vo is 2 × Vref-Vi, Vo is the output voltage of the operational amplifier, and Vi is the voltage signal output by the voltage transformer.

The display module comprises an LED nixie tube, a 74hc138 decoder for controlling bit selection, a 74hc595 device for controlling segment selection and a triode for driving the LED nixie tube; the segment selection means displaying specific numerical values, and the bit selection means which group of nixie tubes are displayed.

Three rows of nixie tubes are adopted, the first row of nixie tubes displays the data of the A phase, the second row of nixie tubes displays the data of the B phase, and the third row of nixie tubes displays the data of the C phase.

74HC595 is an 8-bit shift buffer with serial input and parallel output, and by adopting the device, resources can be saved remarkably.

The three-phase voltage detection system further comprises an alarm module and a communication module. And if the voltage is higher than the threshold value or lower than the threshold value, giving an audible and visual alarm.

The communication module is a wireless communication module and is used for sending the field information to a remote monitoring center or a remote terminal, for example, the remote monitoring center is a server, the remote terminal is a personal device such as a mobile phone, and the wireless communication module is a 3G, 4G or 5G module.

The utility model adopts the voltage transformer to obtain three-phase voltage signals and adopts the amplifier to amplify the voltage signals; an ACD unit in the MCU module converts the amplified signals into digital signals and obtains three-phase voltage data through the existing integral calculation; displaying the three-phase voltage data by using a display module;

a reference voltage circuit is adopted to provide reference voltage for the amplifying circuit; to improve signal detection accuracy.

Has the advantages that:

the utility model discloses a three-phase voltage monitoring system is a three-phase voltage monitoring system and method based on C8051F410 singlechip.

The system is divided into two parts of hardware and software, and both the hardware and the software adopt a modular design concept. The core processor adopted by the system hardware is a C8051F410 chip of Xinhualong company, and a 12-bit AD module is integrated in the chip, so that the system can conveniently perform analog-to-digital conversion. A power supply module, a signal processing and function control module, a display module and the like are designed around a C8051F410 chip in the hardware part, and the functions of power supply of a direct current stabilized power supply, sampled signal preprocessing and analog-to-digital conversion, data display and the like are respectively realized. The utility model discloses easy to carry out, circuit design is succinct, and the function is abundant, and measurement accuracy is high, is fit for promoting and implements.

Drawings

FIG. 1 is a system hardware block diagram;

FIG. 2 is a schematic diagram of an amplifying circuit;

FIG. 3 is a circuit diagram of a display panel;

FIG. 4 is a main flow diagram;

FIG. 5 is an initialization flow diagram;

fig. 6 is a sampling flow chart.

Detailed Description

The invention will be described in further detail with reference to the following figures and specific embodiments:

example 1: as shown in FIGS. 1-6, the C8051F410 single chip microcomputer of Cygnal corporation in America is just 1 single chip microcomputer which can meet the requirements of complex high-performance instruments and meters. The system adopts a C8051F410 singlechip as a main control chip.

Sampling technique

The system adopts an alternating current sampling technology. The alternating current sampling integral algorithm formula is as follows:

system hardware design scheme

The hardware circuit design in the system adopts the modularized design concept, and the system hardware circuit mainly comprises a power circuit, a signal processing and main control function circuit, a display circuit, a storage circuit and other sub-function circuits. The general block diagram of the system hardware is shown in fig. 1.

The power module adopts a linear power supply, the voltage of 220V is reduced to 10V by using a transformer, the voltage is stabilized to +5V output by a half-wave rectification circuit and a filter circuit through a 7805 three-terminal voltage stabilizing device, and the power supply module supplies power to a main control function circuit, a display circuit and other sub-circuits of the system.

Design of main control function module

The system uses a voltage transformer with the model number of HKPT31FA, the HKPT31FA is a current type voltage transformer, the current transformer is actually a current transformer with the turn ratio of a primary winding to a secondary winding of 1:1, when the system is used, a current limiting resistor needs to be connected in series with a primary winding, the input and the output of the current transformer are both mA currents, the input voltage cannot be directly applied to a primary winding, a current limiting resistor needs to be connected in series to convert a voltage signal into the mA currents, the mA current signals output by the secondary winding are connected in parallel with a resistor or an I/V conversion circuit to convert the current signals into the voltage signals, the secondary circuit does not allow open circuit for use, and the input rated voltage of the HKPT31 FA.

The main control function module is mainly used for sending A, B, C three-phase voltage signals into the single chip microcomputer for alternating current sampling after a series of changes and processing.

Taking the phase a as an example, the large ac signal of the phase a is converted into a small ac signal through a voltage transformer and output, because the HKPT31FA voltage transformer is a current type voltage transformer, the output signal is a current signal, and the system needs to measure the voltage signal, and the current signal needs to be converted into the voltage signal by connecting a 100 ohm resistor to the output terminal of the voltage transformer during the design. Because the output waveform of the alternating current signal is a sine wave, the voltage value in one period has positive and negative values, in order to facilitate the calculation of software, an amplifying circuit is adopted to amplify the signal during the hardware design, namely, the signal is raised and amplified, so that the signal waveform is distributed above a zero point, the negative value operation is avoided during the software calculation, and the amplification factor of the amplifying circuit is 2 times. The alternating voltage signal output by the operational amplifier is directly transmitted to an AD channel in the single chip microcomputer after passing through a protection circuit and a filter circuit. In order to facilitate the sampling calculation of data, a direct current voltage VREF is introduced during the design of system hardware, VREF is a reference voltage (direct current voltage 2.2V) output by a single chip microcomputer, the reference voltage VREF is divided into 1.1V by a resistance voltage dividing circuit, a voltage following circuit is designed for enhancing the stability of the direct current voltage, a direct current signal passing through the voltage following circuit and an A alternating current voltage signal after operational amplification enter a P1.0 port of the single chip microcomputer together, and then analog-to-digital conversion and sampling calculation are carried out by an ADC (analog-to-digital converter) in the chip. B. The processing and conveying processes of the C-phase signals are the same as those of the A-phase signals, and the C-phase signals are respectively sent to the P1.1 pin and the P1.3 pin of the single chip microcomputer, so that the A, B, C three-phase signals are processed, conveyed and sampled. The schematic diagram of the system master control function circuit is shown in fig. 2.

The driving chip of the display module adopts a 74HC595 chip.

Designing a display circuit: the LED nixie tube has high cost performance, is widely applied to a common single chip microcomputer system, and displays the acquired voltage signal by using the LED nixie tube. The display module adopts three rows of four-in-one sharing-positive nixie tubes to display, the 74hc138 decoder controls bit selection and the 74hc595 decoder controls segment selection, the first row of nixie tubes displays data of an A phase, the second row of nixie tubes displays data of a B phase, and the third row of nixie tubes displays data of a C phase. Because the signal from the singlechip generates a certain voltage drop after passing through the decoder, the triode is used for driving the nixie tube to display in consideration of the problem of display effect. The system display panel circuit diagram is shown in fig. 3.

Designing a storage module: the system uses a serial EEPROM model AT24c02, conforming to the I2C bus protocol.

The key circuit is mainly used for setting menu parameters, K1 is a confirmation key, K2 is an addition key, K3 is a subtraction key, the key input adopts a static scanning inquiry working mode, the low level is effective, the user menu setting is entered by pressing the K1 key (5 s) for a long time, and the system automatically stores data after the parameters are set. Wherein K1 is linked to the P0.2 port of the single chip microcomputer, K2 is linked to the P0.1 port of the single chip microcomputer, and K3 is linked to the P0.0 port of the single chip microcomputer.

The sampling module performs a series of operations such as A/D conversion, AD integration, waveform processing and sampling signal processing on the voltage signal sent to the singlechip. The program flow chart is shown in fig. 6.

The designed system has strong practicability, low cost and small risk, and can be widely applied to control systems, energy management systems, community electric power monitoring systems and various automatic control systems. The system has the following characteristics:

(1) the true effective value measures three-phase voltage parameters, namely RMS measurement, and the precision grade is 0.5;

(2) the input and the output are fully isolated, the anti-interference capability is strong, and the stability is good;

(3) the environmental adaptability is strong: the temperature is-10 to 55 ℃, and the humidity can work normally within the range of less than 85 percent.

However, due to knowledge limitation, the system needs to be optimized in actual operation, the operation stability of the system is improved, and the system is implemented, produced and applied by adopting industrialized standards.

The utility model discloses characteristics:

(1) the power module is manufactured by adopting a half-wave rectification technology, and is stabilized to 5v through 7805 to supply power to a system, so that the design requirement is met;

(2) the design of the main control function, the commercial power signal is converted into an alternating current small signal in proportion through a voltage transformer, then the signal is lifted in a proper amount through an LM324, and the alternating current small signal is transmitted to a single chip microcomputer through a filtering, voltage stabilizing and protecting circuit to carry out alternating current synchronous measurement, so that the system can monitor the voltage in real time;

(3) the design of the display module adopts a nixie tube dynamic display technology, and can realize the real-time display of the sampling calculation result;

the system is a three-phase voltage monitoring system based on a C8051F410 single chip microcomputer, completely meets design requirements in function, is applied to practical situations, is low in cost and high in precision, has remarkable practicability, and is suitable for popularization and implementation.

Claims (1)

1. A three-phase voltage monitoring system is characterized by comprising an MCU, a power supply module, a sampling module and a display module;

the power supply module, the sampling module and the display module are all connected with the MCU;

the power supply module is used for supplying power to the MCU;

the sampling module comprises a voltage transformer, an amplifying circuit and a reference voltage circuit; the number of the voltage transformers is 3, and the voltage transformers are used for respectively acquiring three-phase voltage signals; the amplifying circuit is based on the operational amplifier, the reference voltage circuit provides reference voltage for the operational amplifier, the number of the amplifying circuits is 3, the amplifying circuits are respectively connected with the output ends of 3 voltage transformers, and the output ends of the 3 amplifying circuits are connected with 3 ADC ports of the MCU;

the reference voltage circuit provides a reference voltage of 1.1V for the operational amplifier;

the reference voltage circuit further comprises an operational amplifier based voltage follower;

the output end of the reference voltage circuit is respectively connected with the inverting input ends of the operational amplifiers of the 3 amplifying circuits through resistors R7-R9;

the non-inverting input ends of the operational amplifiers of the 3 amplifying circuits are respectively connected with 3 voltage transformers;

a resistor is connected between the inverting input end and the output end of each operational amplifier in a bridging manner, and 3 resistors are respectively R10, R11 and R12; the output ends of the operational amplifiers of the 3 amplifying circuits are respectively connected with 3 ADC ports of the MUC;

the display module comprises an LED nixie tube, a 74hc138 decoder for controlling bit selection, a 74hc595 device for controlling segment selection and a triode for driving the LED nixie tube;

adopting three rows of nixie tubes, wherein the first row of nixie tubes displays the data of the phase A, the second row of nixie tubes displays the data of the phase B, and the third row of nixie tubes displays the data of the phase C;

the device also comprises an alarm module and a communication module;

the communication module is a wireless communication module.

Images