A Synchronized Lissajous-based Approach to Achieve Situational Awareness Using Synchronized Waveform Measurements

This paper proposes a new method to achieve situational awareness in power distribution systems. The proposed method uses synchronized data from waveform measurement units (WMUs); which are an emerging class of smart grid sensors. WMUs provide GPS-synchronized voltage waveform and current waveform measurements. In the center of the proposed method is to construct synchronized Lissajous curve; where we plot the voltage waveform versus the current waveform measurements. Under normal operating conditions, the synchronized Lissajous curve shows an ellipse; however, once an event occurs in the network, the shape of the Lissajous curve may change. The changes depend on the type of the event, the location of the event, and other characteristics of the event. Therefore, an event can be characterized based on the changes in the synchronized Lissajous curve. These changes, such as in the area of the synchronized Lissajous curve, can be used also to detect an event, even if the duration of the event is very short. Importantly, the proposed method does not require any prior information of the network as it only requires data from as few as only two WMUs. We examine the performance of the proposed method on the IEEE 33-bus test system for the cases of different events including sustained events, such as equipment switching, and temporary events, such as incipient faults.