Research Of Voltage Sag On-Line Inspection Device

With the continuous development of the national economy and the increasing need of electricity, more and more sensitive devices used in power system, These devices bring great convenience to people's lives. For these sensitive devices only several cycles of Voltage sig and interruption are the main reason for the sensitive devices working abnormal. We have a lot of difficult in researching, but we have not yet had national standard for voltage sig and voltage interruption, it has brought a lot difficult on researching.In consideration of the study state in and outside China, According to IEEE and IEC definition of voltage sag, this paper first details on voltage sag and it's characteristic quantities definition. And then the most-used arithmetic is introduced, including RMS calculation method, fundamental component method, d-q transformation method, instantaneous reactive power method and wavelet transform analysis. At last through the analysis and comparison of various algorithms, based on the national standard of on-line detection device of power quality at present, the RMS calculation method is chose as the voltage sag detection algorithm. Programmed by C language and assembly language, including hardware system initialization subroutine, the algorithm process, voltage sag characteristics of judgments and the amount of testing procedures, using Code Composer Studio 2.0 integrated development environment for debugging software.This device is based on the TI TMS320vc5402DSP to expand power quality inspection device of Henan Enpri Company, and it will be able to detect voltage sag. Expansion of the circuit including 2×64KRAM, provides the operating environment for DSP program,1×4K dual-port RAM is used as data storage area, and to transfer data with power quality detection device PQW-M05; DSP peripheral circuit is also including the simulation interface, power supply and reset circuit.After the hardware and software debugged over and over again, so that the device not only can achieve rapidly detection of voltage sag, but also can detect voltage swell and voltage interruption.