Grid Modernization: Seamless Integration of Protection, Optimization and Control

The objectives of smart grid and grid modernization are to increase automation and seamlessly integrate data, models, protection, optimization and control of the power grid. This effort is affected by technological advances. One such technology is the numerical relay which has increased its domination to the point that today has almost completely displaced electromechanical and solid state relays and the most recent technology of merging units that has separated the data acquisition function from protective relays and SCADA systems. The capabilities of the numerical relays are not fully utilized today, specifically, by and large, they simply mimic the logics that were developed for the electromechanical relays but with much more flexibility. Recent developments towards substation automation are utilizing the numerical relays for SCADA, communications and in general an integrated system for protection and control. These approaches indicate the recognition that numerical relays offer much more than simply mimicking protection functions of the past. They also offer the ability to form the basic infrastructure towards a fully automated power system, the subject of this paper. In previous work, we presented a new protection scheme that is a generalization of differential protection. The approach is based on dynamic state estimation. Specifically, the protection scheme is based on continuously monitoring terminal voltages and currents of the component and other possible quantities such as tap setting, temperature, etc. as appropriate for the component under protection. The monitored data are utilized in a dynamic state estimation that continuously provides the dynamic state of the component. The dynamic state is then used to determine the health of the component. Tripping or no tripping is decided on the basis of the health of the component. The present paper takes the above concept one step further. Using the dynamic state estimation of a protection zone as the basic technology, it builds an integrated automation system that performs the protection functions, validates models, transmits the models to the control center, integrates monitoring and control, enables optimization and provides automated disturbance playback capabilities. The system provides the infrastructure and real time models for any application along the spatial extend of the power system.