Design and implementation of hybrid Kalman filter for state estimation of power system under unbalanced loads

Abstract

State estimation technique plays a vital role in predicting the stability of the power system and is done by estimating the primary variables (states) of the system. Voltage magnitudes (V) and angles (δ) at network buses define the state of a power system. Supervisory control and data acquisition is used to monitor and control the power system state variables where in accurate state variable estimation is quite complex due to the presence of noise in the measured data. State estimation (SE) using conventional techniques such as weighted least square, regularised least square, Kalman filter predict the state vectors with still random error due to its parametric limitations. This study proposes hybrid Kalman filter based SE where the limitation in efficient handling of more number of variables using Kalman filter is addressed by regularising the state variables with constrains and the results are validated for 62-bus Indian utility system. The simulation results explain the operational efficiency of the hybrid Kalman filtering method under various load variation conditions and the results are compared with SE using conventional Kalman filtering method.

Keywords

• Kalman filters
• power system state estimation
• state vectors
• 62-bus Indian utility system
• supervisory control and data acquisition
• SE technique
• hybrid Kalman filtering method
• power system state variable estimation technique
• power system stability
• power system state variable control
• regularised least square techniques
• weighted least square techniques