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The thyristor converter is a core equipment for AC/DC hybrid power grids of high‐voltage direct current (HVDC) where overheating does harm to its reliability. In reality, overheating is closely related to the broken three‐phase symmetry when the AC side is disturbed. Particularly, when commutation failures occur, the valve forced to reconduct will suffer from severe short‐circuit current for a long period, risking the overheating damage. Therefore, the accurate measurement of valve current is fundamental to acquire valve temperature. This paper adopts a real‐time virtual measurement scheme, which is based on temporal features of the converter terminal current, to calculate valve current fundamental for the calculation of valve loss under the transient state. Then, an equivalent circuit model is built based on the actual heat‐flow path of the converter valve, considering the high thermal sensitivity of the heat source material layer. Next, a monitoring system for transient valve temperature is established. Finally, the proposed method is tested in CIGRE HVDC benchmark model. The simulation results indicate that the proposed method can reflect the actual valve state, and model the actual heat transfer process more accurately compared to the Foster network, which can support the basic configuration of the overheat protection. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a time-varying model-based method for estimating earthquake-induced displacement responses of building structures using limited acceleration data. First, a time-varying model which considers the variability of stiffness by a time-variant story local stiffness reduction factor and the variability of damping by formulating the Rayleigh damping model with a time-variant mass coefficient was developed. Then, a displacement estimation algorithm was derived on the basis of the state space representation of the time-varying model and the unscented Kalman filter. The effectiveness of the proposed method is numerically verified through nonlinear responses of a ten-story building model where the hysteretic restoring force is simulated by the Bouc–Wen model. In addition, numerical results indicated that a few sensors with low noise are more desirable for the measurement strategy. Finally, the applicability to realistic seismic monitoring of buildings was investigated through a 1∶3-scale 18-story steel frame test at the E-Defense shaking table facility, which tested collapse behavior and realistic damage of high-rise steel buildings constructed in the 1990s in Japan. [ABSTRACT FROM AUTHOR]