The Research Of One Method For Voltage Sag Source Location In The Power Grid

With the extensive use of new technology in industrial and rapid development ofnew kinds of load, the request of customers to power quality has been increasinglyhigh. As the main cause of production faults of sensitive load, voltage sag has becomeone of the most outstanding problems. The accurate location of voltage sag source notonly provides criterion to the quantitative assessment of responsibility for powerquality problems, but also contributes to ifnd and solve the voltage sag events, whichcan help the market participants to improve adverse effects using targeting measuresto obtain better economic beneifts.Most voltage sag source location methods focus on the position relative tomonitoring device. The one based upon disturbance power and energy influencesother new ways most. The improvement and priority of disturbance energy based onClarke’s components to original method has been tested by simulation experiment,which provide the theoretical basis for voltage sag source location in terms of thewhole grid.The number of existing methods to find the accurate location use a limitednumber of monitoring equipments in a power grid is not very high compared to theones that identify the relative positions. This paper presents one new way to track thevoltage sag source in a power system based on branch current measurements anddisturbance energy. Firstly, voltage sag monitoring placement optimization is beendetermined by the analysis of grid dip region and system fault-current sensitivity. Themost influenced nodes are chosen as monitored ones，in the request of observability ofthe ’whole system. Secondly, the norm deviation index of each branch currentsClark,es components is used to characterize the current change before and atfer thesag, which can track the disturbance source location within an area, confined by thedisturbance energy directions of the top-priority branches. The IEEE30-bus testsystem with voltage sag events caused by various faults in different load nodes is used to illustrate the usefulness of the proposed method. Simulation results obtained by theproposed method show that it is efifcient and accurate, especially in a large systemwith numerous nodes. Because it can track the source area of voltage sags quickly,which only consists of several nodes. The capacitor switching is also one commonpower quality disturbance. The simulation and its results analysis of capacitorswitching disturbance in the mentioned system has proved that the voltage sag sourcelocation method based on branch current deviation and disturbance energy is alsoapplied to find the location of shunt capacitor switching transients.