Study On The Detection Of Voltage Sags And Its Compensation Methods

The improvement of power quality in power system has attracted more and more attentions of people in the field of scholar, power apartments and users both domestic and abroad. Voltage sags has been the most serious problem in power quality. So,the exact detection of the characteristics of voltage sags and fast voltage compensation can bring tremendous economic benefit. It is important to research the subject about voltage sags.In this paper,firstly, methods of distinguishing interruption course resulted in voltage sags are given compendiously. The following content is the core of this paper—studying on the detection methods of voltage sags. Above all,the paper analyzed the merits and defaults of all kinds of present methods to detect voltage sags, and compared one with another. Then, at the basis of newest detection method namedαβtransformation method applied on single phase,this paper proposes an improved detection method of voltage sags characteristics which uses differential coefficient instead of phase delay that is employed inαβtransform method for the voltage sags detection. The improved method achieves fast and accurate detection of voltage sags characteristics, which not only accelerates the detection speed, but also overcomes short-time disturbance appearing in the detection waveform caused by phase delay inαβtransform method. So, the improved method presented in this paper enhances the detection accuracy and speed which is very useful for the following compensation device (DVR). The simulation results verify the validity of the method proposed for DVR.In this paper, the most serious power quality problem-voltage sags-is introduced comprehensively, form its conception, courses and results to distinguishing its interruption courses, detecting its characteristics, studying on its compensation methods and introducing the structures of its compensation equipment. It can provide the profound basis for the future research on this subject.