Design Of Power Quality Analyzer Based On Dual Embedded Controller

There have been plenty of power quality problems with the development of distributed electricity generation technologies and applications of nonlinear time-varying topology load power electronics. These problems have posed a threat to the security and reliability of the power supply system and become an important research topic of smart grid construction. Real-time monitoring of power quality is very important as a basis for smart grid construction.China has developed a number of national standards of power quality, but because of the late start on power quality research, there is still a certain gap with Western developed countries, especially in the development and application of power quality monitoring products. Therefore, the subject designed a online real-time monitoring power quality analyzer in accordance with the relevant requirements of the national standards, combined with the requirements of analyzer’s performance, referring to the advantages of similar products.This paper described the relevant national standards of power quality, referring to the relevant literature, summed up the overall functional requirements of power quality analyzer, and choose dual embedded controller to achieve them. Then, the paper analyzed common power quality problems, summarized the power signal waveform characteristics and identification method when different types of power quality problems occur and then proposed using wavelet transform and fast Fourier transform algorithm in combination for power quality analysis.Electric power quality parameters can be measured by the quality analyzer is divided into steady state parameters, transient disturbance events and SOE information. The analyzer has a data storage module for storing the electric energy quality data, it also has the operation monitoring function and over limit alarm function, the alarm threshold can be set by the user according to the actual needs, alarm data also can be stored. In order to provide the time stamp information which is required by the data storage, the clock circuit is designed. The clock circuit can operate independently and the time also can be set through the communication. This power quality analyzer can be interconnected with other intelligent electronic devices through Ethernet interface conforms to IEC61850protocol for the real-time transmission of data.According to the specific algorithm and function demand of this analyzer, this analyzer used DSC+ARM dual embedded controller. ADSP-CM408, with built-in float point unit, was choosen as digital signal controller and mainly responsible for electrical signal acquisition, FFT transform, wavelet transform and communication with ARM etc.Based on the analyzer’s hardware design, software design is as follows:DSC does not use embedded operating system. ARM use open source operating system μC/OS-II, it will need to complete a reasonable division of functions for different tasks, the operating system is responsible for switching tasks when the program is running.In order to verify the performance of this power quality analyzer, this paper finally carried out plenty of testing, proved that the analyzer can meet the requirements of this design. Finally, this paper analyzed the deviations of test results and proposed corresponding solutions.