Li Zhang

The operational reliability of shaft systems in hydropower units has become increasingly critical as these units are frequently engaged in grid regulation under new power systems. This paper presents a sensor-driven method for operational status assessment and trend prediction of Francis turbine generator unit shaft systems using vibration and swing signals. Time domain features are extracted from the sensor-acquired signals to construct a multi-dimensional quantitative index system for characterizing the operational state, and a combined Entropy Weight–Coefficient of Variation–TOPSIS model with dynamic health thresholds is established for adaptive condition assessment. To address the nonlinear and non-stationary characteristics inherent in such signals, a decomposition–prediction–reconstruction fusion framework is developed, incorporating Variational Mode Decomposition (VMD) for signal decomposition and noise reduction, iTransformer for capturing global multi-variable interactions, and Bidirectional Long Short-Term Memory (BiLSTM) for bidirectional temporal feature extraction. The hybrid model achieves a coefficient of determination R² of 0.9845 on complex vibration and swing signals, demonstrating its superior prediction capability. Based on the prediction results, health scores and dynamic thresholds are calculated to perform trend analysis and health early warning. A case study is conducted using real-world monitoring data from a 306 MW Francis turbine unit. The results demonstrate that the proposed method effectively characterizes the shaft system operational state, achieving a closed-loop integration from condition monitoring to fault diagnosis and predictive maintenance. The operational status assessment and trend prediction analyses are in good agreement with actual operating conditions, providing reliable technical support for the intelligent health management of hydropower units.

To address the limited adaptability of fixed thresholds and the inherent drawbacks of single weighting methods in bearing state assessment, this paper proposes a bearing health evaluation model that integrates the entropy weight method, the variation coefficient method, and TOPSIS. Firstly, multi-dimensional time-domain features are extracted from bearing vibration signals to serve as health indicators. Then, indicator weights are determined by combining the entropy weight and variation coefficient methods, and Kendall’s coefficient of concordance is used to examine the agreement between the two weighting schemes. A comprehensive health score is subsequently computed using TOPSIS, and a dynamic health threshold is established based on the 3σ rule, enabling quantitative assessment of bearing health. Finally, the proposed approach is validated using the IEEE PHM 2012 bearing degradation dataset. Experimental results demonstrate that the method effectively tracks the full-lifecycle degradation of bearings from healthy operation through rapid deterioration to ultimate failure. The health score curve remains smooth during the healthy stage, the onset of degradation is accurately identified, and the overall evaluation performance surpasses that of single weighting methods. This paper provides valuable technical support for bearing health assessment and predictive maintenance.

Accurate identification of the rotational moment of inertia of a top drive system is essential for dynamic modeling, control design, and performance optimization in drilling operations. However, the strong coupling between the drive motor, transmission components, and drill string makes direct inertia measurement challenging under field conditions. To address this issue, this study proposes a moment of inertia identification method based on dynamic response analysis of the top drive system. A simplified torsional dynamic model is established by representing the top drive and drill string assembly as an equivalent lumped inertia system. By applying controlled torque excitation under no-load conditions, the system’s angular velocity response is measured and analyzed in both time and frequency domains. The relationship between applied torque and angular acceleration is utilized to identify the equivalent rotational inertia through parameter estimation. Experimental results indicate that low-frequency excitation provides more favorable conditions for reliable and accurate inertia identification, yielding improved stability and reduced estimation error compared with higher-frequency inputs. In addition, frequency response characteristics are investigated to validate the consistency and robustness of the identified inertia across different excitation frequencies. Experimental results obtained from a top drive test rig demonstrate that the proposed method can reliably estimate the equivalent moment of inertia with good repeatability under controlled experimental conditions. The identified inertia shows good agreement with theoretical calculations and exhibits stable behavior over a wide frequency range. The proposed approach avoids the need for additional sensors or structural modifications and is well suited for practical engineering applications. This study provides an effective and experimentally validated method for inertia identification of top drive systems, offering valuable support for dynamic modeling, control parameter tuning, and vibration analysis in drilling engineering.

As fundamental prerequisites for the operation and maintenance (O&M) of hydroelectric units, situation awareness and health management have emerged as research hotspots in recent years. Bioinspired intelligence, with advantages such as high efficiency, environmental adaptability, robust performance, and transferability, provides new research ideas, methods, and applications for the O&M of hydroelectric units, especially in situation awareness and health management. This paper reviews the prospects, current applications, and technical challenges of bioinspired intelligence in situation awareness and health management of hydroelectric units from the perspective of reliability-centered maintenance (RCM). First, the technical requirements and features of situation awareness and health management for hydroelectric units in RCM are elucidated. Next, the technical frameworks of hydroelectric units are reviewed from the perspective of bioinspired intelligence. A detailed discussion is then provided regarding the relevant implementation strategies in multiple domains, including real-time monitoring, multi-source signal fusion, state characteristic extraction, intelligent health diagnostics, maintenance decision-making optimization, and smart O&M systems. Finally, future trends and development opportunities in applying bioinspired intelligence to situation awareness and health management of hydroelectric units are proposed: integrating the advantages of bioinspired intelligence with the engineering requirements of RCM and innovating approaches for intelligent O&M, which would provide further support for safe, reliable, and efficient energy systems.

Southwestern China has abundant hydropower networks, wherein neighboring cascade hydropower stations within the same river basin are typically connected to the power system in a chain-structured configuration. However, when such chain-structured cascade hydroelectric power plants (CC-HPPs) participate in automatic voltage control (AVC), problems such as reactive power interactions among stations and unreasonable voltage gradients frequently arise. To address these issues, this study proposes an optimized multi-station coordinated response control strategy based on sensitivity analysis and hierarchical AVC. Firstly, based on the topology of the chain-structured hydropower sending-end network, a reactive power–voltage sensitivity matrix is constructed. Subsequently, a regional-voltage-coordinated regulation model is developed using sensitivity analysis, followed by the establishment of a mathematical model, solution algorithm, and operational procedure for multi-station AVC-coordinated response optimization. Finally, case studies based on the actual operational data of a CC-HPP network validate the effectiveness of the proposed strategy, and simulation results demonstrate that the approach reduces the interstation reactive power pulling up to 97.76% and improves the voltage gradient rationality by 16.67%. These results substantially improve grid stability and operational efficiency while establishing a more adaptable voltage control framework for large-scale hydropower integration. Furthermore, they provide a practical foundation for future advancements in multi-scenario hydropower regulation, enhanced coordination strategies, and predictive control capabilities within clean energy systems.