Introduction

State estimation in power systems is a key element of Energy Management Systems (EMS). A state estimator collects field measurement data from remote terminal units via data transmission networks like Supervisory Control and Data Acquisition (SCADA) systems. Using a set of non-linear equations that relates the measurements of power system states (such as bus voltage and phase angle), the state estimator optimizes the power system state variables by minimizing the sum of the squared residuals. This process is known as the Weighted Least Squares (WLS) method.

The mathematical formulation of the WLS state estimation algorithm for an n-bus power system with m measurements is provided below:

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