A novel voltage sag source detection method using TFR technique

Voltage sag is considered as the major power quality disturbance that can disrupt the operation of sensitive equipment. Many power utilities around the world install power quality recorders at strategic sites to monitor the frequency and severity of voltage sags that may affect their customers. The immediate identification of sources of voltage sags is very critical in providing information to customers to resume back their operations. The sources of voltage sags can originate either from upstream or downstream with respect to the monitoring point. This paper presents a novel method to identify the sources of voltage sags using a signal processing technique called the S-transform (ST). An index named S-Transform Disturbance Power (STDP) was developed to identify the origin of the voltage sags. The results of this study showed that the novel method is superior to the other methods in detecting the origin of both symmetrical and asymmetrical voltage sag in actual power systems.