CN106680617A - Wireless sampling-based electric energy quality test and analysis device - Google Patents

Abstract

At present, most of the traditional designs of power quality analyzers use industrial computers equipped with data acquisition cards to realize data collection and analysis of power quality, mainly for monitoring steady-state indicators. The real-time performance of the system is difficult to guarantee, and the level of intelligence and networking is not high. . The present invention relates to the field of power quality testing, and provides a power quality testing and analysis device based on wireless sampling. The device includes a wireless sampling unit and a digital power quality analysis unit; the wireless sampling unit is connected to the secondary side of the power system. The synchronous signal of the power quality analysis unit simultaneously sends the collected data to the digital power quality analysis unit via wireless; The data is analyzed and processed, so that the wireless test and analysis of power quality can be realized.

Description

Power quality test and analysis device based on wireless sampling

technical field

The invention relates to the field of power quality testing, in particular to a power quality testing and analyzing device based on wireless sampling.

Background technique

Since the 1980s, some power quality monitors for power systems and power quality analyzers for user terminals have appeared in foreign markets. Most of the traditional designs of power quality analyzers use industrial computers equipped with data acquisition cards to achieve data collection and analysis of power quality, mainly for monitoring steady-state indicators, the real-time performance of the system is difficult to guarantee, and the level of intelligence and networking is not high. With the rapid development and wide application of digital signal processing technology, the use of digital detection of power quality has become a new hotspot in the development of current and future power quality detection technology.

The voltage and current signals required by the current power quality analyzers are directly connected to the power quality analyzer body through the test line. This connection method is reliable and the signal attenuation is small, but the secondary side of the tested object needs to be connected with the power quality analyzer. Direct connection makes it inconvenient to fix the test line. If the test line is not fixed firmly, it will easily cause a short circuit of the secondary voltage or an open circuit of the secondary current, and the safety risk is relatively large during operation. In addition, it is troublesome to connect and disconnect the wires every time during the test. At the same time, it is necessary to use the power cable reel to pull the wires from a long distance to supply power to the power quality analyzer. The long-distance wires are easy to be unplugged or tripped, resulting in test interruption and data loss. At the same time, it is difficult to find a suitable power supply for power quality analyzers in some substations in rural areas. Long-distance cable power supply and test circuit wiring are many and complicated, and the supervision span of the entire test process is difficult.

Contents of the invention

In order to solve the above problems, the present invention provides a power quality test and analysis device based on wireless sampling. The device does not require long-distance cable power supply and the test circuit wiring is simple. The specific technical solution is as follows:

The power quality test and analysis device based on wireless sampling includes a wireless sampling unit and a digital power quality analysis unit; The data is sent to the digital power quality analysis unit through wireless; the power quality analysis unit realizes the synchronous collection of the wireless sampling unit through wireless, and at the same time receives the data with time stamp from the wireless sampling unit for analysis and processing.

Further, the wireless sampling unit includes a voltage/current transformer module, a signal conditioning module, an A/D sampling module, a microprocessor MCU module, a WIFI module, and a power supply module; the voltage/current transformer module is connected to the system secondary The voltage transformer of the side voltage changes into a 10V low-voltage signal, and the current transformer connected to the secondary side current of the system becomes a 10V low-voltage signal. Both signals are output to the signal conditioning module; the signal conditioning module converts the voltage/ The signal transformed by the current transformer module is adjusted to the allowable input range of the A/D chip of the A/D sampling module -2.5~+2.5V, and the signal transformed by the voltage (current) transformer module is filtered. , after the higher harmonics are filtered out and the signal is output to the A/D sampling module; the A/D sampling module samples the output signal from the signal conditioning module; the microprocessor MCU module controls the A/D sampling The module samples and reads data, and sends the sampled data wirelessly to the digital power quality analysis unit through the WIFI module; the WIFI module receives the synchronization signal from the digital power quality analysis unit, and sends the data with time stamp collected by the microprocessor MCU module. Voltage and current data; the power supply module obtains power from the voltage transformer, and provides various voltage levels of power required by the wireless sampling unit through step-down conversion to maintain the work of each chip and processor.

Further, the digital power quality analysis unit includes a working power supply module, a communication interface module, a data processing module, a setting display module, data storage and a real-time clock module; the working power supply module provides various voltages required by the digital power quality analysis unit Grade power supply, used to maintain the work of each chip and data processing module; the communication interface module provides wireless WIFI, Ethernet communication interface, wireless WIFI receives the voltage and current data collected by the wireless sampling unit, and Ethernet is used for digital electric energy The quality analysis unit is connected with the upper computer PC; the data processing module performs Fourier decomposition on the received data to calculate the voltage, current value, each harmonic and total harmonic distortion rate, and three-phase voltage unbalance , flicker value; the setting display module is used for parameter setting, data and indicator display; the data storage and real-time clock module is used for storing statistics, analysis reports and data, real-time display time and synchronous three-phase wireless sampling unit Data sampling.

Further, the wireless sampling unit contains a magnet.

Further, a grounding resistor is connected before the voltage signal enters the A/D sampling module.

Further, the error range of the signal conditioning circuit is 0-0.1% in amplitude, the output signal is -2.5-+2.5V, and the cut-off frequency of the second-order active low-pass filter is greater than 3kHz.

The wireless sampling-based power quality testing and analysis device provided by the present invention solves the troublesome connection between the voltage and current test terminals of the existing portable power quality analyzer and the analyzer, which causes the risk of electric shock and requires a long-distance cable power supply, which has potential safety hazards. The problem. The voltage of the voltage transformer is not only sampled by the wireless sampling unit, but also provides the main working power for the unit, solving the problem of difficulty in obtaining power for the device. The wireless sampling unit contains magnets, which can be easily fixed in the electrical screen cabinet. The power quality analysis unit realizes the synchronous acquisition between wireless sampling units through wireless, and simultaneously receives and analyzes and processes the data with time scale from each wireless sampling unit. All in all, the power quality analysis device based on wireless sampling can realize the test and analysis of power quality without directly connecting the tested voltage and current signals through the test line.

Description of drawings

Fig. 1 is a schematic structural diagram of a power quality testing and analyzing device based on wireless sampling.

detailed description

The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention, and the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the implementation examples in the invention, all other implementation examples obtained by persons of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

Fig. 1 is a schematic structural diagram of a power quality test and analysis device based on wireless sampling, which includes a wireless sampling unit and a digital power quality analysis unit. Among them, the wireless sampling unit includes a voltage (current) transformer module, a signal conditioning module, an A/D sampling module, a microprocessor MCU module, a WIFI module, and a power supply module; the digital power quality analysis unit includes a working power supply module, a communication interface module, Data processing module, setting display module, data storage and real-time clock module. The wireless sampling-based power quality test and analysis device connects the secondary side voltage and current signals of the power system to the voltage (current) transformer module, adjusts them to the input range allowed by the A/D chip through the signal conditioning module, and sends them to To the A/D sampling module, the microprocessor MCU receives the synchronous signal from the digital power quality analysis unit, the microprocessor MCU controls the A/D chip to start collecting voltage and current signals, and the microprocessor MCU reads the collected band Time-scaled voltage and current data are sent to the digital power quality analysis unit. The digital power quality analysis unit performs Fourier decomposition on the received data to obtain power quality indicators such as voltage, current value, each harmonic and total harmonic distortion rate, three-phase voltage unbalance, and flicker value.

Preferably, the voltage converter in the voltage (current) transformer module adopts the TR1102-2C type detection voltage output type voltage converter, the specifications are Krl=100V/10V, and the current converter adopts the TR0102-2C type detection Use a voltage output type current converter, and the specifications are Kr2=5A/10V.

The signal conditioning module is set to sample 256 points per cycle of the measured signal, that is, the sampling frequency is 12.8ksps. In order to accurately measure the 50th harmonic, it is necessary to filter out the components above 2.5kHz, and determine the overall design goal of the signal conditioning circuit: the error range is 0~0.1% of the amplitude, and the output signal size is -2.5~+2.5V , the low-pass filter cutoff frequency is greater than 3kHz. Preferably, a TLC2272 operational amplifier with low noise and full power supply amplitude is used to condition the input signal to form a second-order active low-pass filter to filter out high-frequency interference signals higher than 3KHz in the sampling signal. This method also has sampling The two functions of filtering and filtering are simple in principle, easy to implement, and have high precision. They can effectively suppress high-frequency interference and better maintain signal purity. In order to prevent the chips in the circuit from being damaged due to a large current flowing through the signal conditioning module, a grounding resistor is connected before the voltage signal enters the A/D sampling module.

Preferably, the A/D sampling module adopts a 16-bit A/D converter AD7665 with low power consumption and low cost, which can perform synchronous sampling of 2 analog signals or asynchronous sampling of 4 analog signals. In this device, there are 1 voltage and 1 current signal in the 1-phase wireless sampling unit, and AD7665 can satisfy the synchronous sampling of 2 analog signals.

Preferably, the microprocessor MCU module adopts the LPC1343 of NXP Company based on Cortex-M3, which has the advantages of high integration and low power consumption, and the USB interface can easily interface the LPC1343 with the WIFI module.

Preferably, the WIFI module is designed with a low-power chip RT5572, supports 2T2R baseband and 2.4GHz/5GHz dual-band, the maximum transmission rate is 300Mbps, and complies with IEEE 802.11a/b/g/n standards.

Preferably, the power supply module in the wireless sampling unit adopts wide voltage input AH7550 chip to generate 5.0V voltage and TPS79533 chip to generate 3.3V voltage.

Preferably, the external input power supply of the working power module in the digital power quality analysis unit is AC 220V. After rectification and step-down conversion, the AE2596 chip is used to generate 5V, the AS1117M3-3.3 chip is used to generate 3.3V and the AS1117M3-1.8 is used to generate 1.8V. Three voltage levels.

Preferably, the communication interface module adopts low-power Ethernet PHY chip DM9161, which is compatible with 10M/100M, TI's RF transceiver CC2520, realizes the physical layer of Ethernet, has selectivity/coexistence and excellent link budget function characteristics , to meet the requirements of proprietary wireless systems in various applications, and provides a wide range of hardware support, including packet processing, data buffering, burst transmission, data encryption, data authentication, clear channel assessment, link quality indication and packet timing information etc.

Preferably, the data processing module adopts the high-performance ARM9 processor AT91SAM9260 of ATMEL Company as the core, and has rich interfaces such as Ethernet MAC, dedicated LCD interface, and USB.

Preferably, the display module is set to use a 7-inch TFT LCD capacitive screen with a resolution of 800x480.

Preferably, the data storage and real-time clock module adopts the K9F2G08 chip for the external 256M Nand FLASH, the HY57V64162 chip for the external 64M SDRAM, and the PCF8563 chip produced by PHILIPS for the real-time clock. Low-power multi-function clock/calendar chip, with multiple alarm functions, timer functions, clock output functions and interrupt output functions, can complete various complex timing services and even provide watchdog functions for ARM9 Internal clock circuit and The internal oscillation circuit, internal low voltage detection circuit, and I2C bus communication method not only make the peripheral circuit extremely simple but also improve the reliability of the chip. At the same time, the embedded word address register will automatically increase after each read and write data.

Claims (6)

1. The power quality test and analysis device based on wireless sampling is characterized in that: it includes a wireless sampling unit and a digital power quality analysis unit; synchronous signal, and at the same time, the collected data is sent to the digital power quality analysis unit wirelessly; the digital power quality analysis unit realizes the synchronous collection of the wireless sampling unit through wireless, and simultaneously receives and analyzes the data with time stamp from the wireless sampling unit and processing. 2. The power quality testing and analysis device based on wireless sampling according to claim 1, wherein the wireless sampling unit includes a voltage/current transformer module, a signal conditioning module, an A/D sampling module, and a microprocessor MCU Module, WIFI module, power module; the voltage/current transformer module connected to the voltage transformer of the secondary side voltage of the system changes into a 10V low voltage signal, and the current transformer connected to the secondary side current of the system becomes a 10V low voltage signal signal, both signals are output to the signal conditioning module; the signal conditioning module adjusts the signal transformed by the voltage/current transformer module to the allowable input range of the A/D chip of the A/D sampling module -2.5~+2.5 Within V, at the same time, the signal transformed by the voltage (current) transformer module is filtered, and the high-order harmonics are filtered out and the signal is output to the A/D sampling module; the A/D sampling module The output signal of the signal conditioning module is sampled; the microprocessor MCU module controls the A/D sampling module to sample and read data, and the sampled data is wirelessly sent to the digital power quality analysis unit through the WIFI module; the WIFI module receives data from Digitalize the synchronous signal of the power quality analysis unit, and send the voltage and current data with time scale collected by the microprocessor MCU module; A power supply of various voltage levels is used to maintain the work of each chip and processor. 3. The power quality testing and analyzing device based on wireless sampling according to claim 1, characterized in that: the digital power quality analysis unit includes a working power supply module, a communication interface module, a data processing module, a display module, data storage and A real-time clock module; the working power supply module provides various voltage level power supplies required by the digital power quality analysis unit to maintain the work of each chip and data processing module; the communication interface module provides wireless WIFI, Ethernet communication interface , the wireless WIFI receives the voltage and current data collected by the wireless sampling unit, and the Ethernet is used for connection between the digitized power quality analysis unit and the upper computer PC; the data processing module performs Fourier decomposition calculation on the received data to obtain Voltage, current value, each harmonic and total harmonic distortion rate, three-phase voltage unbalance, and flicker value; the setting and display module is used for parameter setting, data and index display; the data storage and real-time clock module It is used to store statistics, analyze reports and data, display time in real time and synchronize data sampling of three-phase wireless sampling units. 4. The wireless sampling-based power quality testing and analyzing device according to claim 1, characterized in that: said wireless sampling unit contains a magnet. 5. The wireless sampling-based power quality testing and analyzing device according to claim 1, wherein a grounding resistor is connected before the voltage signal enters the A/D sampling module. 6. The wireless sampling-based power quality testing and analyzing device according to claim 1, characterized in that: the error range of the signal conditioning module is 0-0.1% in amplitude, and the output signal is -2.5-+2.5V, The cut-off frequency of the second-order active low-pass filter is greater than 3kHz.