Research On Harmonic Suppression And Forewarning System Of Electric Power Grid Based On DSP

The abnormal phenomenon of the electrical and the electronic devices, which caused by the decline of power quality due to harmonics on the electric power grid, has brought to people’s attention as early as the start of the electric power supply. With the improvement of living standards and the expansion of industrial scales, the electric power consumption in all departments has been on great increase. Besides, the new types of power electronic products have been widely used. All of these have brought very tremendous influence to the distortion of the electrical power wave, which makes the harmonic suppression become more difficult. This paper namely takes the harmonic suppression scheme as the object of study, concerns about harmonic detection, analysis and compensation, and thus constructs a set of harmonic suppression and forewarning system.Generally, harmonic suppression can be achieved by two steps. The first is to determine the ingredients of harmonic and the second is to decide the method of harmonic compensation. The first step mainly focuses on harmonic detection and analysis, and this paper will propose an algorithm called Siding-Pruning-FFT. It bases on the FFT algorithm and combines the characteristics of harmonic analysis on electric power, which improves the applicability and the efficiency of FFT algorithm. This algorithm will be realized on the high performance DSP. As for the harmonic compensation method in second step, the traditional passive filter can not meet the demand of fast and dynamic compensation. So the active power filter with excellent reliability, remarkable dynamic performance and high precision becomes the trends of harmonic compensation method. This paper combines the advantages of passive filter and active power filter, proposes a hybrid active power filter based on the intelligent power module, which increases the compensation precision, the dynamic performance and the capacity.Besides, the system also has the function of forewarning. It can detect the over voltage and over current fault of the electric power grid as well as under voltage and short circuit fault of the intelligent power module, and provide the forewarning signal along with protection operation. The detection and forewarning message will be shown on LCD. The system has reserved the RS232 interface to communicate with computer.The hardware as well as the software design is on the principle of modularization and encapsulation. The hardware is divided into DSP smallest system board, data collection board, power drive board, and man-machine interface board, which can reduce the debugging difficulty, the development cycle, and enhance the stability. The commonly used code is also encapsulated into a module, which improves the reusability of the code. Meanwhile, some program interface has been reserved on the software design for further renewal.This paper will start with the background of harmonic suppression, and then give the detail introduction of the design principle and the process of hardware and software design. After that, the experiment result of the system will be shown and analyzed. At the end of the paper is the conclusion and further study direction.