An Approximate Method for Transient State Estimation

Voltage dip is a frequently occurring power-quality problem that electricity consumers face. Knowledge of the source and magnitude of the voltage dip is desirable; however, complete monitoring of the power system is prohibitive. State estimation for both fundamental and harmonic frequencies was presented previously. Its ability to utilize limited measurements for system-wide estimation has proven to be very effective. In this paper, the technique is extended further to estimate power system transients. Transient state estimation (TSE) provides an effective and systematic approach in locating and identifying remote fault sources, thus allowing the problem to be addressed more efficiently. The proposed approach formulates the system using state-space theory and results in a system of first-order differential equations which are used to form the measurement system. The estimation is the simultaneous solution of the measurement system equations based on a time sequence of snapshots of the system measurements. Additional measurement information utilizes the voltage and current history measurements where they are approximated using backward Euler integration formula, are also supplied to the TSE algorithm. To evaluate the performance of the proposed TSE, transients caused by a sudden lost of a system load have been simulated on the test system. This paper provides a new methodology to estimate a complete transient profile of a power system.