Synchrophasor based tracking of synchronous generator dynamic states using a fast EKF with unknown mechanical torque and field voltage

Dynamic states of a synchronous machine, i.e. rotor angle and rotor speed, are important variables for power system control, studies and analysis. Availability or estimating of these variables would help us to monitor effectively the stability condition of the power systems in order to develop local or wide-area control loop to improve power system stability and reliability. To estimate the rotor angle or rotor speed of a synchronous machine, availability, measuring or estimating the input signals, i.e. field voltage (E_fd) and input mechanical torque (T_m) is always an issue. To solve this problem, in this paper the Extended Kaiman Filter with Unknown Inputs, known as EKF-UI method, is applied for dynamic state estimation of a synchronous generator using available Phasor Measurement Unit (PMU) signals while we are assuming there are two unknown inputs: E_fd and T_m. Using the employed EKF-UI technique, the unknown input signals of the synchronous machine (E_fd and T_m) are estimated simultaneously along with the states and outputs of the machine.