Estimation of electromechanical modes under ambient condition through random decrement technique and PRCE algorithm

An accurate awareness of characteristics of the electromechanical oscillation modes is essential for the secure operation of the power systems. The random decrement technique (RDT) is used with the multi reference point complex index (PRCE) which was formerly applied to analyze the vibration characteristics of mechanism structures to estimating the inter-area electromechanical modes during ambient condition, including the frequencies, damping ratios and the mode shapes. A Monte Carlo simulations were conducted to evaluate the performances of the RDT-PRCE method in a statistical way. Simulation results based on the 16-machine system indicate that the proposed method can provide a more accurate estimated results compared with the RDT-TLS-ESPRIT method and NExT-ERA method, also, the RDT-PRCE method is highly robust against measurement noise. The RDT-PRCE method was also applied to actual measurements from Sichuan power grid of China. The results show that the RTD-PRCE method is valid and fast enough to be implemented in the real-time use.