Estimation and control in electric energy systems based on time-stamped signals

Electric power systems are among most spatially extended engineered systems. Their stable operation in the presence of disturbances and outages is made possible by real-time control over communication networks. Communication delay is one of the unavoidable side-effects of using a computer network to interconnect sensors, actuators and control centers/nodes. We propose here a delay canceling approach based on time-stamping of transmitted signals, which can successfully mitigate the destabilizing effects of delay. Time stamping is enabled by the availability of precise time signals derived from the Global Positioning System (GPS) in various nodes of the power system. Such signals are part of Phasor Measurement Units (PMUs) that are increasingly being deployed as a key ingredient of system-wide monitoring and control. We show that our time-stamping-based delay canceling method makes it possible to overcome very large delays in the estimation-control loop while avoiding adverse effects on the stability of the system.