Real-time Detection Of Power Quality

With the rapid increase of non-linear load capacity specially widely-used power electronic devices, power pollution becomes more and more serious. On the other hand, all sorts of complex and precise apparatuses ,which are sensitive to power quality, are increasingly connecting to the Power Net, therefore customers demand much higher power quality for their apparatuses. How to improve power quality (PQ ) to supply the customers with High-Quality Power has become a research focus both at home and abroad.Firstly, the thesis summarized the causes and hazards of PQ problem and measures and steps for harnessing the problem. It also contained latest development of PQ measurement. Secondly, in terms of PQ Standard, algorithms for measuring major PQ index were discussed in length. Through simulations and comparison, extensive research was made on several algorithms applicable for Real-time PQ measurement, which laid the solid theory ground for the design of Real-Time PQ Instrument. PQ Disturbance is another crucial indicator of PQ. Fortunately wavelet analysis provides a powerful tool for detecting PQ disturbances. In this thesis, different types of PQ disturbances were analyzed using wavelet and merits and faults of different wavelets in detecting disturbances were discussed in detail. Finally a Fuzzy Evaluation System was adopted for classifying the PQ.Based on the algorithms discussed above, the author developed the core circuit for Real-Time PQ measurement using a DSP, a CPLD and other peripheral devices. Test results showed: l)The circuit can meet the need of Real-Time measurement for several PQ index. 2) The frame structure based on DSP and CPLD is a foreseeable proposal for Real-Time PQ measurement.