PMU Data Buffering for Power System State Estimators

State estimation (SE) is a critical must run successful unit within energy management system software. This is dictated by the high reliability requirements for system security and control and the need to represent the closest real-time model for market operations. There has been considerable emphasis in bringing phasor measurements into SE to improve performance. However, there are many practical problems in incorporating phasor measurements into SE. The higher reporting rates of phasor measurement units compared with supervisory control and data acquisition devices is one such problem. The disparity of the reporting rates raises the question of whether buffering the phasor measurements helps to improve the state estimates. This buffer is a subset of the entire phasor measurements set relevant to every particular instant at which SE is conducted. This paper describes the design of an optimal buffer, the use of the phasor measurements from that buffer, and the analysis of the impact on SE with the inclusion of these buffered phasor measurements. This hybrid SE, used for analysis purposes, is created from contemporary real-time system data and measurements from a utility in southwest USA.