The Development Of Power Quality Terminal Detection Source

With the wide application of power electronic devices in the power grid,especially the proportion of non-linear loads has increased,resulting in a large number of harmonics and inter-harmonic pollution in the power grid,which causes power quality degradation,affecting the safe operation of the power system.In view of this situation,power quality detectors have been developed both at home and abroad to realize real-time monitoring of the status of the power grid.After the detector is connected to the network,it must be regularly tested to ensure that the performance of the detector is up to standard.The power quality terminal detection source developed in this project can provide a standard signal source for the performance test of the detector.The power quality terminal detection source can output three-phase voltage and three-phase current signals at the same time.The output of fundamental wave,harmonics,and interharmonic signals can be used for the static performance test of the detector.The amplitude modulated wave signal can be used for dynamic performance testing.The device uses the 1PPS generated by the GPS module as the synchronous signal,adopts the architecture of three-ARM and the meter-source integration design.The data exchange between the ARMs is realized through the SPI(Serial Peripheral interface)communication interface with the DMA(Direct Memory Access)function,it realizes the characteristics of fast transmission speed and high reliability,and ensures the real-time and accuracy of the output signal.The device is composed of the communication control part,the waveform output part,the sampling processing part,each part chooses the STM32F407ZGT6 microprocessor based on the CORTEX-M4 kernel.The communication control part receives the GPS message acquisition time information through the serial port,realizes the range automatic switching through the control circuit,realizes the human-computer interaction through the touch-sensitive screen,has the function of the real-time monitoring of the fault,the fault protection,the coefficient adjustment,the data processing and the computation.The waveform output part generates basic wave,harmonic,interharmonic,and amplitude modulated waveform data through querying a 360000-point high-capacity cosine table and using the waveform synthesis algorithm,and then outputs the small signal of voltage and current synchronized with 1PPS by the 16-bit dual-channel D/A chip DAC8822 with high-speed and high-precision performance,through high-speed power amplifier circuit for small-signal power amplification and output,,it has amplitude and phase fine-tuning function,and can realize accurate adjustment of output signal.The sample processing part synchronously samples the output signal through 16-bit high-speed and high-precision A/D chip ADS8568,and the signal amplitude and phase are obtained by FFT operation of the sampled data.This paper first introduces the research background and significance of the subject,compares the present research situation at home and abroad,then explains the main research contents of this subject,and expounds the content arrangement of each chapter briefly.According to the requirements of the main functions and performance indicators of the device,the generation methods of each waveform signal and the simulation implementation process of the corresponding algorithm are introduced in turn.Then,the two parts of the device’s hardware design and software design are introduced in turn through circuit diagrams and flow charts.Then the hardware and software of the device are combined to debug and adjusts the coefficient of the device using a standard meter RD-33 of 0.01 grade,perform functional test,record the test data,analyze the error reason and put forward the improvement method,the test result shows that the performance index of the device is standard.Finally,the paper summarizes and forecasts the design.