Minimum information loss based state estimation for power systems

The mathematical base of state estimation (SE) method for power systems is studied based on information theory. A more general SE method based on the minimum information loss (MIL) principle is proposed. The new method is suitable for different probability distributions of measurement errors, it can utilize different types of information including that of analog and digital measurements, and a unified estimation of power flow and network topology can be performed by it. It is proved that weighted least square (WLS) and weighted least absolute value (WLAV) estimation methods are both special cases of the MIL estimation. Based on the MIL method, it is concluded that large magnitude currents are the approximate condition of WLS estimations for current magnitude measurements commonly used in SE's for sub-transmission and distribution networks. A statistical study of a small test case and a numerical experiment in a real power network are carried out