Fusion estimation for a class of multi-rate power systems with randomly occurring SCADA measurement delays

Abstract

In this paper, the fusion estimation problem is investigated for a class of multi-rate power systems with randomly occurring delays in supervisory control and data acquisition (SCADA) measurements. The power system is measured by the SCADA and the phasor measurement unit (PMU), and the state updating period of the power system is allowed to be different from the sampling periods of the SCADA and the PMU. The phenomenon of the randomly occurring SCADA measurement delays is characterized by a set of Bernoulli distributed random variables. To facilitate the state estimator design, a new approach is developed to transform the multi-rate power system into single-rate one. First, two local state estimators are designed, respectively, based on the SCADA and the PMU measurements such that upper bounds of the local estimation error covariances are guaranteed at each sampling instant, and such upper bounds are subsequently minimized by appropriately designing the gains of both local state estimators. Then, the asynchronous estimates from the local state estimators are fused by recurring to the covariance intersection fusion scheme. Finally, a simulation experiment is carried out on the IEEE 14-bus system to illustrate the effectiveness of the proposed fusion estimation scheme.