CN106526379A - Method for implementing power quality test analysis based on wireless sampling - Google Patents

Abstract

Power quality is tested and analyzed by using a power quality analyzer at present, this method needs long-distance stayed power supply and many and complex test circuit wires, and the supervision span of the whole test process is difficult. The invention relates to the field of power quality test, and particularly to a method for implementing power quality test analysis based on wireless sampling. The method specifically comprises the steps of: a wireless sampling unit connecting voltage and current of the secondary side of a power system, receiving a synchronous signal from a digital power quality analysis unit, and simultaneously wirelessly sending the acquired data to the digital power quality analysis unit; the digital power quality analysis unit wirelessly implementing synchronous acquisition of the wireless sampling unit, simultaneously receiving data carrying time scales from the wireless sampling unit, analyzing and processing the data, thus realizing power quality test analysis. The method does not need long-distance stayed power supply, is simple in test circuit wire connection and disconnection and low in time consumption and improves the working efficiency, and the whole test process is small in supervision span and easy to realize.

Description

A Method of Realizing Power Quality Test and Analysis Based on Wireless Sampling

technical field

The invention relates to the field of power quality testing, in particular to a method for realizing power quality testing and analysis based on wireless sampling.

Background technique

At present, the power quality analyzer is used to test and analyze the power quality. This method needs to directly connect the voltage and current signals to the power quality analyzer body through the test line. Although this connection method is reliable and the signal attenuation is small, the secondary side of the tested object It needs to be directly connected to the power quality analyzer, which is inconvenient to fix the test line. If the test line is not fixed firmly, it will easily cause the secondary voltage short circuit or the secondary current open circuit. The safety risk is relatively large during operation. It is more troublesome. At the same time, it is necessary to use the power cable reel to pull the wire from a long distance to supply power to the power quality analyzer. The long-distance pull wire is easy to be unplugged or tripped, resulting in test interruption and data loss. The power supply for the power quality analyzer. This test method has the disadvantages of needing long-distance cable power supply, many and complicated test circuit wiring, and difficulty in monitoring the entire test process.

Contents of the invention

In order to solve the above problems, the present invention provides a method for testing and analyzing power quality based on wireless sampling. The specific technical solutions are as follows:

The wireless sampling unit is connected to the voltage and current of the secondary side of the power system, receives the synchronization signal from the digital power quality analysis unit, and at the same time sends the collected data to the digital power quality analysis unit through wireless, and the digital power quality analysis unit realizes wireless sampling through wireless The synchronous acquisition of the unit, simultaneously receiving and analyzing and processing the time-marked data from the wireless sampling unit, includes the following steps:

(1) Sampling unit connection: connect the voltage clamp to the secondary side of the voltage transformer, and the current clamp to the secondary side of the current transformer, turn on the power switch of the wireless sampling unit, and wait for the wireless pairing connection;

(2) The digital power quality analysis unit is connected with the sampling unit: turn on the digital power quality analysis unit, connect the power supply, start the machine, and establish a connection with the wireless sampling unit;

(3) Setting parameters: set parameters such as voltage and current transformation ratio, and compare the voltage, current, active and reactive values and phases with the actual voltage, current, active and reactive values to ensure that the wiring and transformation ratio settings are correct;

(4) Start the test: check whether the wireless sampling unit has been fixed, and start the formal measurement;

(5) End the test: After the test is completed, first stop the digital power quality analysis unit, then turn off the power of the wireless sampling unit, remove the wireless sampling unit, perform preliminary data analysis, and check the data integrity;

(6) Restore the site and end this test: remove the power cord and network cable of the digital power quality analysis unit, pack the digital power quality analysis unit and wireless sampling unit, restore the site, and end the test.

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 , the numerical value of the flicker value; the setting display module is used for parameter setting, data and index 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 The unit's data samples.

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 module 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 beneficial effects of the present invention are: the method for realizing power quality testing and analysis based on wireless sampling does not require long-distance cable power supply, the test circuit connection and disconnection are simple and not time-consuming, the work efficiency is improved, and the supervision span of the whole test process is small and easy to implement.

Description of drawings

Fig. 1 is a flow chart of the steps of a method for realizing power quality testing and analysis based on wireless sampling;

Fig. 2 is a structural diagram of a device for testing and analyzing power quality based on wireless sampling.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

The wireless sampling unit is connected to the voltage and current of the secondary side of the power system, receives the synchronization signal from the digital power quality analysis unit, and at the same time sends the collected data to the digital power quality analysis unit through wireless, and the digital power quality analysis unit realizes wireless sampling through wireless The synchronous acquisition of the unit, at the same time receive the data with time scale from the wireless sampling unit and analyze and process it. Specifically, it performs Fourier decomposition to calculate the voltage, current value, each harmonic and total harmonic Value of voltage unbalance, flicker value. The method includes the following steps:

(1) Sampling unit connection: connect the voltage clamp to the secondary side of the voltage transformer, and the current clamp to the secondary side of the current transformer, turn on the power switch of the wireless sampling unit, and wait for the wireless pairing connection;

(2) The digital power quality analysis unit is connected with the sampling unit: turn on the digital power quality analysis unit, connect the power supply, start the machine, and establish a connection with the wireless sampling unit;

(3) Setting parameters: set parameters such as voltage and current transformation ratio, and compare the voltage, current, active and reactive values and phases with the actual voltage, current, active and reactive values to ensure that the wiring and transformation ratio settings are correct;

(4) Start the test: check whether the wireless sampling unit has been fixed, and start the formal measurement;

(5) End the test: After the test is completed, first stop the digital power quality analysis unit, then turn off the power of the wireless sampling unit, remove the wireless sampling unit, perform preliminary data analysis, and check the data integrity;

(6) Restore the site and end this test: remove the power cord and network cable of the digital power quality analysis unit, pack the digital power quality analysis unit and wireless sampling unit, restore the site, and end the test.

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. 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 Voltage output type current converter, 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 the present invention, there are 1 voltage and 1 current signal in the 1-phase wireless sampling unit, and the 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, with a maximum transmission rate of 300Mbps, and complies with IEEE802.11a/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.

The digital power quality analysis unit includes a working power supply module, a communication interface module, a data processing module, a setting display module, a data storage and a real-time clock module. 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 ATMEL company's high-performance ARM9 processor AT91SAM9260 as the core, with 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.

The present invention is not limited to the specific implementation manners described above. The above descriptions are only preferred implementation examples of the present invention, and are not intended to limit the present invention. Any modifications and equivalents made within the spirit and principles of the present invention Replacement and improvement, etc., should be included within the protection scope of the present invention.

Claims (6)

1. A method for realizing power quality testing and analysis based on wireless sampling, characterized in that: the wireless sampling unit is connected to the voltage and current of the secondary side of the power system, receives a synchronous signal from a digital power quality analysis unit, and simultaneously passes the collected data through Send wirelessly to the digital power quality analysis unit, and the digital power quality analysis unit realizes the synchronous acquisition of the wireless sampling unit through wireless, and simultaneously receives and analyzes and processes the data with time scale from the wireless sampling unit, including the following steps: (1) Wireless sampling unit connection: connect the voltage clamp to the secondary side of the voltage transformer, clamp the current clamp to the secondary side of the current transformer, turn on the power switch of the wireless sampling unit, and wait for the wireless pairing connection; (2) The digital power quality analysis unit is connected with the sampling unit: turn on the digital power quality analysis unit, connect the power supply, start the machine, and establish a connection with the wireless sampling unit; (3) Setting parameters: set voltage and current transformation ratio parameters, compare the voltage, current, active and reactive values and phases with the actual voltage, current, active and reactive values to ensure that the wiring and transformation ratio settings are correct; (4) Start the test: check whether the wireless sampling unit has been fixed, and start the formal measurement; (5) End the test: After the test is completed, first stop the digital power quality analysis unit, then turn off the power of the wireless sampling unit, remove the wireless sampling unit, perform preliminary data analysis, and check the data integrity; (6) Restore the site and end this test: remove the power cord and network cable of the digital power quality analysis unit, pack the digital power quality analysis unit and wireless sampling unit, restore the site, and end the test. 2. A method for realizing power quality testing and analysis 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, a micro Processor MCU module, WIFI module, power supply module; the voltage transformer connected to the system secondary side voltage of the voltage/current transformer module changes into a 10V low voltage signal, and the current transformer connected to the system secondary side current becomes 10V low-voltage 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 Within ~+2.5V, filter the signal transformed by the voltage/current transformer module at the same time, filter out the high-order harmonics and output the signal to the A/D sampling module; the A/D sampling module Sampling the output signal from the signal conditioning module; the microprocessor MCU module controls the A/D sampling module to sample and read data, and wirelessly sends the sampled data to the digital power quality analysis unit through the WIFI module; the WIFI module Receive the synchronization signal from the digital power quality analysis unit, and send the voltage and current data with time scale collected by the microprocessor MCU module; the power module obtains power from the voltage transformer, and provides the wireless sampling unit with the Power supplies of various voltage levels required to maintain the work of each chip and processor. 3. A method for realizing power quality testing and analysis based on wireless sampling according to claim 1, characterized in that: said digitized 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 real-time clock module; the working power supply module provides various voltage level power supplies required by the digital power quality analysis unit for maintaining the work of each chip and data processing module; the communication interface module provides wireless WIFI, Ethernet The communication interface, the wireless WIFI receives the voltage and current data collected by the wireless sampling unit, and the Ethernet is used for the connection between the digitized power quality analysis unit and the upper computer PC; the data processing module performs Fourier decomposition on the received data Calculate the values of 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 The storage and real-time clock module is used to store statistics, analysis reports and data, display time in real time and synchronize data sampling of the three-phase wireless sampling unit. 4. A method for testing and analyzing power quality based on wireless sampling according to claim 1, characterized in that: said wireless sampling unit contains a magnet. 5. A method for testing and analyzing power quality based on wireless sampling according to claim 2, wherein a grounding resistor is connected before the voltage signal enters the A/D sampling module. 6. A method for testing and analyzing power quality based on wireless sampling according to claim 2, characterized in that: the error range of the signal conditioning module is 0-0.1% in amplitude, and the output signal size is -2.5~+ 2.5V, the cut-off frequency of the second-order active low-pass filter is greater than 3kHz.