Study Of Voltage Sag Source Location In Distribution Network

As an important aspect of power quality, voltage sag has become one of the most concern problems. Voltage sag source location is of great significance to improve quality power and reduce the economic loss. This paper first discusses the theory and characteristics of the existing location methods, according to the locating principle and characteristics and other content, the existing locating methods are classified into five categories. Four methods of two categories are compared based on simulation mainly, the locating effect is discussed in details under the function of symmetry and asymmetric faults using the four methods. Slope of the system trajectory method and real current component method are modified against the insufficiency, which improve the location effect. Aiming at the insufficiency of the distance relay method, an improved voltage sag source location method is proposed based on the change rate of impedance magnitude and increment of impedance angle, the simulation and application in actual system indicates that the proposed improved method can impove the testing precision.Different types of short-circuit fault can lead to different sag phenomena. Combined with seven basic types of voltage sag and amplitude variation characteristics and the effect of transformer and load connection as well as different characteristics of sequence components of different sag types, a method of short-circuit fault type recognition based on judging the voltage sag type is proposed, which applies symmetrical component method and information of sag amplitude, the feasibility of this method is demonstrated through simulation analysis.