An Advanced State Estimation Method Using Virtual Meters

-  Power system state estimation is a central component in energy management systems of power system. The goal of state estimation is to determine the system status and power flow of transmission lines. This paper presents an advanced state estimation algorithm based on weighted least square (WLS) criteria by introducing virtual meters. For each bus of network, except slack bus, a virtual meter is considered, using the concept of KCL law. Regarding virtual meter, an improved state estimation algorithm is obtained with higher accuracy and lower computation burden. In the case study, at first, a simple 6-bus test system is presented and the proposed state estimation algorithm is followed step by step. Then, in order to evaluate the effectiveness and applicability of algorithm, IEEE 30-bus and IEEE 118-bus test systems are also taken into consideration. The obtained results verify the usefulness of the proposed method in large size power systems including thousands of buses

State Estimation – New Models on Power Distribution Networks Based on Weighted Least Squares Method in Line Current Measurements

Calculation of Load Flow distribution is an important tool in Electrical Engineering that involves numerical analysis applied to Power Systems. State Estimation techniques have been developed and applied thoroughly mainly in the levels of generation and transmission. Research in the distribution level remains a challenge due to the intrinsic characteristics of the network. Introducing line current measurements in the state estimation process constitutes an additional issue due to distribution networks characteristics. In order to overcome these difficulties, it is necessary to develop mathematical models that simulate the behavior of those networks. The solution of the problem of state estimation by the least squares method, sometimes presents a bad conditioning of the gain matrix. Solving a badly conditioned problem results in a proximity to the singularity of the coefficient matrix. Also, the use of line current measurements in the state estimation process leads to numeric and observability problems in the systems including the cancelation of elements in the jacobian matrix in the plain state, which means that those measures are useless when starting from plain state. Also, the non-linearity of equations causes convergence difficulties in the iterative process. The proposed work consisted of: (i) developing a state estimator for a determined radial network, (ii) introducing state variables of the developed method, (iii) comparing them with previously published work, (iv) determining the influence of estimating parameters instead of using measured values, and (v) verifying the validity of developed model using PowerWorld simulation software