Real-time Estimation of Multi-port Thevenin Equivalents for Power Systems with Non-accessible Parameters

In this paper, a novel method is proposed for the real-time estimation of multi-port Thevenin equivalent circuit parameters of power systems with non-accessible parameters using synchronized measurements from capacitive voltage transformers (CVT) and power analyzer. The core of the proposed approach is founded on simultaneous measurements at boundary buses, enabling real-time Thevenin equivalent circuit estimation, bus voltage phasor determination, and calculation of power flow across interconnecting lines. The key innovation in the proposed method is the accurate and continuous modeling of the inaccessible network based on the accurate instantaneous calculation of the variable transmission line impedance. Also, to reduce the impact of measurement noise, additional measurements and the least squares equation solving technique are used, which consequently increases the modeling accuracy to a great extent. Furthermore, to prevent misleading results caused by significant error magnitudes, the method incorporates a disturbance tracking algorithm to identify the direction and minimal intensity of disturbance sources. The effectiveness of the proposed methodology has been validated through simulations conducted in Dig-SILENT power factory application. The high accuracy of the proposed method in comparison with literature is shown by applying them to the IEEE ۳۹-bus power system. In comparing the values obtained from their estimation and use of load distribution under different conditions, the maximum relative error rate of the best previous method is ۹.۹%, while the error of the presented method without using PMU and RTU is less than ۵%.

کلیدواژه ها:

Capacitive voltage transformers measurement ، non-accessible parameters ، Power analyzer measurement unit ، Power system estimation ، Real-time estimation ، Synchronized measurement ، Thevenin equivalent circuit