Phase 1 of this project, namely the Phasor Measurement Unit (PMU) applications state-of-the art assessment, was completed and reported in August 2012. In the present report, the completed activities of Phase 2 are explained.
The idea pursued in this phase is the innovative application of PMUs for generation shedding (also known as generation rejection). In other words, appropriate voltage magnitudes and angles (to be obtained from properly located PMUs) will be processed to derive the right amount of generation shedding required for every relevant contingency and under all applicable conditions. The equal-area criterion concept is examined for utilization wherever possible, but is rejected wherever it is inadequate. The application is demonstrated on a BC Hydro case and its variations, which are modified and tailored to facilitate the simulations for the purposes of this study, as well as keeping the case generalized for application to other systems.
The main focus is on the fast generation shedding required for transient security, namely transient stability, acceptable transient voltage dips, and proper damping of oscillations. Slower shedding, however, is also addressed from other points of view, such as voltage stability, branch overloads, and selection of proper margins. The whole process developed in this phase of the project is divided into four stages: locating PMUs, developing the algorithms for fast and slow generation shedding, deriving fast generation shedding rules, and deriving slow generation shedding rules.
The developed PMU placement process, the algorithms for shedding estimations, and the rules drawn for fast and slow shedding requirements are not only innovative, but also possess the necessary robustness without being excessively complex. The proposed scheme provides significant potential cost savings as it projects the required generation shedding using the conditions at hand rather than on prior assumptions of worst-case conditions. Moreover, the procedures are kept general so that they can easily be applied to other systems using any commercially-available transient-stability simulation package.
Keywords: Phasor Measurement Unit (PMU), Angle Difference, Equal-Area Criterion (EAC), Critical Clearing Time (CCT), Generation Shedding/Rejection, Transient Security, Voltage Security