On-line Power Quality Monitoring System Design Based On DSP And Embedded Platform

As the power quality of industrial processes have become increasingly demanding,transient power quality detection and treatment cause more and more attention. Powerquality disturbances are transient voltage spikes, voltage gap, high-frequencyinterference, voltage sag, voltage swell and voltage interruption, etc. Transient powerquality disturbance detection methods include Fourier transform, S-transform, discretecosine transforms and wavelet transform and so on. Wavelet transform, a branch ofapplied mathematics, and developed in the late1980s, enjoy the "mathematicalmicroscope" reputation. Fast Fourier transform (FFT) and Discrete Fourier Transform(DTFT) have already used in some of the foreign enbeded system products forimplementing power quality online measure. Such products are often consisting ofcomplex algorithms, expensive hardware, therefore, the cost of such product areusually higher as well. But in the real use, only certain frequencies need to extractinformation, to identenfy the type of power quality disturbances.In recent years, with the computer and integrated circuit technology becomingmore and more matured, the development of embedded systems is rapid. With reliable,more powerful, small size, flexibility and low cost hardware and softwareconfigurations, embedded systems are ideal for low-level (or site) system applications,such as robots, mining equipment, distribution multi-agent communication systems.The emergence of embedded systems for power quality monitoring system designed toprovide the necessary intelligent hardware platform. In power quality analysis systems, DSP system is mainly used in data processing, while ARM embedded processor act asthe system’s main CPU, which is responsible for the data, transmission and controlfunctions such as human-computer interaction ensuring the real-time and reliability ofthe system under the premise, as far as possible to reduce costs, considered a shortdevelopment cycle. At present, the international dual-core ARM+DSP combinationhas a certain structure of the application, and has appeared ARM core and DSP corewill be integrated. Whether international or domestic, based on ARM+DSPevaluation board hardware system is not ready-made a lot. Research and to build sucha dual-core platform, has some research value. This design platform based ondual-core power quality detection analyzer, mainly to complete the following research:1. Choose the method of wavelet transform for power quality monitoring. In thispaper, based on various types of power quality analysis and comparison of existingmethods to determine on the basis of the status of embedded systems, selection can beimplemented in the existing implementation, which has a relatively high efficiency ofjudgment. So that using the wavelet transform method is with the advantage comparedwith other methods. And selecting mother wavelet, determining the frequency of thewavelet decomposition level and transforming are the three steps. The Haar wavelettransform method can achieve power quality analysis. Finally, by way of Matlabsimulation of a number of samples, the feasibility of the algorithm can be verified.2. Design embedded hardware implementation platform. According to theprinciple of wavelet transform analysis, the appropriate hardwares are selected as theimplementation platform. Integrate the hardware platform for the realization of thevarious power quality monitor functions and modules, as well as specific hardwaremodule implementation process. And to choose has to achieve the DSP+ARM as coreof the system. Around the DSP+ARM core computing and control, the ADC chip, theHall device, graphics chips, GPRS transmission module and other major peripheral chips are selected, and related circuit are designed. Complete the various modules tomeet real-time computing requirements of the hardware design platform solutions.3. Design embedded software implementation platform. Based on DSP+ARMarchitecture, functionality and requirements analysis for power quality analyzer, andwith the DSP integrated development environment, ARM integrated developmentenvironment, and Qtopia development environment, we achieved starting DSP, startingARM, algorithmic programming, the algorithm efficiency improvment, AD sampling,GPRS transmission and LCD display system software implementation. Byimplementing each of the above software modules, the system can be running. DSPmakes the system able to provide the best possible use of hardware resources andcomputing power to complete real-time wavelet calculations. While ARM has theoperating system uClinux embedded in the system to achieve the convenience ofinterpersonal interaction.