Search Results (2)

The converter valve is the core equipment of flexible DC transmission, but it has been severely damaged in previous earthquakes. Therefore, the seismic performance of its structure has a significant impact on the safety and reliability of power transmission. To study the seismic performance of ±500 kV flexible DC converter valves and identify weak links in the supporting valve tower, this article first established a refined finite-element model of a valve tower based on its physical structure; then modal analysis on the valve tower was conducted; finally, time-domain analysis of the valve tower under three seismic excitations, namely Wenchuan, EI Centro, and artificial, was conducted, and the equivalent stress and directional displacement cloud maps of the key parts of the valve tower were obtained. The research results indicate that the dynamic characteristics of the valve tower are relatively complex, with low fundamental frequency and diverse natural vibration modes. Under earthquake action, the predominant frequency of EI Centro waves is close to the fundamental frequency of the valve tower, which is prone to resonance and causes significant damage to the valve structure. The improved design of the valve tower meets the seismic strength requirements of level 8 seismic intensity. Full article

Converter valves are the core equipment of offshore wind power structures. However, they are highly vulnerable to vibration under strong earthquakes, which will affect normal operation of the offshore wind farm. Converter station is an axisymmetric structure with obvious asymmetry in its internal configuration of the superstructure. This study aimed to analyze the dynamic response of a supported converter valve in an offshore converter station under seismic excitation. The coupling model of the supported valve tower group and the converter station were established, and the distribution law of the valve tower dynamic response and foundation settlement were investigated. The dynamic response effect of the modal truncation, valve tower stiffness, and basic size on different areas and foundations of the valve towers were studied. The findings were as follows: (i) the effect of local vibration of the valve tower should not be simplified by using equivalent mass and node condensation; (ii) the structure–equipment coupling analysis method should be used to review the structural design scheme of the offshore converter station in the intensity VII region; (iii) the vertical higher-order modes should be considered during the vibration response calculation and its participation ratio in mass should not be lower than 90%; (iv) the frequency range that minimizes the vibration response is the characteristic frequency range of horizontal vibration, while the best vibration suppression effect cannot be obtained in both the horizontal and vertical directions; and (v) the stiffness of the valve tower itself should be adjusted and different stiffness designs of the valve tower in different positions should be adopted to realize effective vibration response control. Full article