Application Of Intelligent Active Power Filter In Electrified Railways Based On DSP

Electrified railways have been rapidly developed; however, the non-linear characteristic (harmonic), the non-symmetry (negative sequence) and increasing volatility of power grid have attracted a lot of unusual incidents, because of the growing pollution of AC-DC electric locomotive to power quality. Therefore, it's necessary to deal with the tram power grid harmonics. But because of the inherent drawbacks, the traditional passive filter can not meet the requirements. Active power filter is capable of reactive power compensation and harmonics filtering, but without the effect of system changes, so it is an ideal scheme. The purpose of this study is to develop APF for harmonics treatment of electrified railway and promote the application and research of APF on electrified railway.This paper studies a kind of digital, modular and high-performance APF, which uses DSP as the core processor and uses highly integrated intelligent power module instead of the traditional discrete components. The APF has two major functions. In addition to the reactive power compensation and harmonic filtering function, it is also used to monitor the operation of the tram power grid. Power grid parameters of real-time detection, including voltage, current, reactive power, active power, power factor, are shown on LCD and transmitted to the PC through PC serial communications. They are also stored in the computer. Intelligent circuits can also dectect several kinds of power grid faults, which include missing phrase, phrase error, overvoltage, undervoltage, overcurrent and so on. In fact, all the work is done by one dedicated energy measurement IC, which not only simplifies the hardware design and reduces the computation load of DSP, but also simplifies the software design and improves the measurement accuracy.This paper first discusses the background of this study, the current research and research significance. The second chapter discusses the structure and working principle of the APF in detail. Instantaneous reactive power theory is also mentioned. On this basis, the third chapter talks about the various components of the circuit design with the TMS320LF2407A as the core processor, according to the APF structure. The whole circuit consists of two main components. Intelligent monitoring system is one part and the active power filter is another. Chapter IV provides the detailed description of the control system software design based on hardware of chapter III. Chapter V covers various optimization measures, because of the inadequate performance of existing APF. These measures including optimizing both the hardware and software significantly improve the performance of the filter. In Chapter VI, the experimental devices are introduced and the results are analyzed. Chapter VII, the final chapter of this paper is a summary of the text. It also gives the direction of further study.