| In recent decades, with the rapid development of the power-related industry, the higherrequirements for the power supply quality are put forward. As the technology improvingconstantly, large number of equipments for the daily life and industrial production have beenapplied widely, which are sensitive to the variation of power source.The power qualityproblems such as electromagnetic interference, which caused by the impact and nonlinearload in power system, make tremendous effect and harm to the manufacturing enterprises andgeneral users. In order to solve the problems rising from the modern power grid and the newtype load, one of the best effective methods is the comprehensive and scientific monitoringfor the power quality.In this paper, based on deeply discussing with the research content of power quality, thetype of power quality can be divided into steady and transient events by alternativephenomena. Steady-state measurements are defined and explained according to the nationalstandard, as well as the calculation methods and limits. Various types of mathematicalanalysis methods are summarized and compared, expecially focusing on FFT.As the part ofmain designed program, it is applied to the steady-state calculation. At the same time, themethod of transient disturbance detection using the difference arithmetic is also investigated,and the software implements are also designed for identifying the initial and the end time.In the condition of depth study with modern power quality monitoring system structureand standard, the hardware structure of DSP and ARM is proposed for the monitoringdevice.In addition, the chip model, DSP peripheral circuit, sampling circuit,signal processingcircuit are also selected and designed.This paper mainly completes the design of DSPinterface circuit, signal processing circuit and ADC sampling module, and describes theprinciples of signal condition, frequency detection, sampling control process. The wholeoperation of DSP is also designed after the hardware circuit design completes, so that the DSPcan realize the whole process from the initialization to each subroutine.Matching the ADsampling procedure, the DSP can implement the main operated function entirely.In order to make the excellent task management function of ARM, the linux operationsystem has been transplanted. The whole transplantation includes the bootloader, kernel andfile system. For the features of open source and free flow, the linux OS can execute thefunction cutting and flexibe configuration, and add the essential supporting documentsaccording to the needs of the device. All that can make linux has a real-time capability, so tomeet the demand of power quality monitoring device. The equipment has been tested in the laboratory, and some suggestions have been put forward for improving the system. |
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