【目的】双碳目标下,燃煤机组正由长期带稳定负荷运行转为灵活性运行,深度调峰能力是衡量燃煤机组灵活性运行的一项重要指标。但深度调峰运行会使得发电机热点温度快速变化,导致绕组变形、绝缘磨损、脱壳及槽楔松动等故障。本文针对深度调峰工况下发电机定子端部运行状态展开研究。【方法】基于COMSOL Multiphysics有限元分析软件,建立了电-磁-力多物理场耦合的定子绕组本体模型,分析了快速变负荷与超低负荷两种深度调峰工况下的线棒与槽楔振动位移情况。进一步地,为了加快发电机适应深度调峰运行,提出了两种定子端部结构优化方案。【结果】仿真结果表明,当负荷以5%/min速率变化时,直线段线棒、槽楔和出槽口线棒位移相比于优化前额定工况下的振动幅度分别降低了21.19%、99.7%和59.05%。当发电机处于30%运行工况下,其位移分别降低了72.46%、99.997%和53.85%。【结论】发电机结构优化后处于极端快速变负荷工况下,直线段线棒、槽楔和出槽口线棒位移幅度显著降低,验证了优化结构的有效性。

[Objective] Under the dual-carbon target, coal-fired units are transitioning from operating under long-term stable loads to flexible operation. The deep peak shaving capability has become a critical indicator of the flexibility of coal-fired power units. However, deep peak shaving operations lead to rapid changes in the generator's hotspot temperatures, causing faults such as winding deformation, insulation wear, delamination, and wedge loosening. This paper investigates the operating state of the stator end of generators under deep peak shaving conditions. [Methods] Using COMSOL Multiphysics finite element analysis software, a multi-physics field coupling model for the stator winding was established, integrating electrical, magnetic, and mechanical fields. The vibration displacement of conductor bars and wedges was analyzed under two deep peak shaving conditions: rapid load variation and ultra-low load. Furthermore, to accelerate the adaptability of generators to deep peak shaving operation, two stator end structure optimization schemes were proposed. [Results] Simulation results showed that when the load changed at a rate of 5%/min, the vibration amplitudes of the straight section conductor bars, wedges, and slot exit conductor bars decreased by 21.19%, 99.7%, and 59.05%, respectively, compared to the original structure under rated conditions. When the generator operated at 30% load, the displacement reductions were 72.46%, 99.997%, and 53.85%, respectively. [Conclusion] After structural optimization, the displacement amplitudes of the straight section conductor bars, wedges and slot exit conductor bars under extreme rapid load variation conditions are significantly reduced, confirming the effectiveness of the optimized structure.

中国华电集团有限公司“揭榜挂帅”项目(CHDKJ22-01-108)