Study On Voltage Flicker Detection Methods

Five items, with frequency, harmonics, voltage deviation and voltage fluctuation and flicker respectively, are included in the state standards of energy quality. With the development of power electronic technology, much nonlinear, impactive and imbalance load emerges in power system. As a result, power quality has deteriorated. The problem of voltage fluctuation and flicker, one issue of power quality, becomes more and more serious. To solve the problem and improve power quality, effective supervision and exact measurement is primary. However, compared with frequency, harmonics, voltage deviation, unbalance of three phases, voltage fluctuation and flicker are more complex to be detected, its research is relative to scarce, and the measuring devices are much less. Hence, some further research on measuring voltage fluctuation and flicker has been done in the paper.As an important index to assess the energy quality, voltage flicker reflects the power supply quality more directly and quickly. The basic concepts and character values of voltage fluctuation and flicker are introduced firstly, and then the common methods of suppress the voltage fluctuation are discussed. Further more, the process of extracting voltage fluctuation signal and calculating flicker values is analyzed, and the principle of detecting voltage fluctuation and flicker is detailed. The analog system of the IEC flicker meter is simulated. Then the algorithm of digital system is studied and the digital design result is presented subsequently. In the paper three methods of calculating Short term flicker severity—P_st that is the flicker evaluation index are discussed. The result proved that the algorithm and method presented to be correct and acceptable. This makes it possible to continue the supervisory and measuring device.