Research On The Application Of Digital Signal Processing In The Detection And Analysis Of Power Quality

With the rapid development of our country's industry and economy, the sharp increase of load, especially the incessant increase of impulsive and nonlinear loads, power quality problems, such as voltage flicker and harmonic, often occur. These power quality problems bring impact on our manufacture and life. Thus, it becomes more and more important to take measures to improve power quality. Nevertheless the detection and analysis of power quality is the primary problem to solve. The thesis focuses on the subject of power quality.Firstly, the domestic and overseas research situations, concepts and standards relevant to power quality are introduced. And the classifications of power quality problems are generalized. Then, voltage flicker is referred with emphasis in three aspects- basic concepts, detection methods and flickermeter. Therefore the foundation of later research is established.On the basis of filter theory, both the analogical system and digital system of IEC flickermeter are devised, according to IEC's and national standard. In the mean time, different statistical methods are adopted to calculate short time flicker value (P_st ), based on the statistic of instantaneous flicker sensation level. In terms of the verification of digital flickermeter system, the digital flickermeter system devised in the thesis meets IEC's and national standards.Based on wavelet transform theory, a novel method -integration of wavelet transform and simulating synchronous signal, is adopted for the detection of voltage flicker signal. And the fundamental, harmonics, emergence time, end time, magnitude and frequency of voltage flicker signal are precisely detected. Moreover, wavelet transform is utilized for the analysis of voltage harmonics, transient voltage disturbance pulse and voltage halt. Then, the harmonics, disturbance pulse, halt time of voltage signal is acquired accurately.In the end, COM technique is introduced. The development strategy, development platform, system function and system structure of power quality analysis software are presented. And the design of power quality analysis software is accomplished in the way of calling Matlab COM component by VC++. Then, the software is applied to analyze the recorded data from traction substation. Consequently, the application in project proves the practicability of the software.