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<p>The electro-hydraulic (EH) system is a critical subsystem of thermal power plant generating units, which regulates the opening of turbine steam valves via solenoid valves. Solenoid valve sticking failure poses a severe threat to the operational safety of generating units. In this study, macroscopic inspection, surface micromorphology analysis, metallographic testing, and hardness measurement were conducted on faulty solenoid valves. The results confirm that valve sticking is induced by three-body abrasive wear. Furthermore, particle composition analysis was performed on oil samples collected from both the EH system oil tank and faulty solenoid valves, verifying that the sticking-causing contaminants are stainless steel particles. Subsequently, the filtration performance of brand-new EH system filter elements was comprehensively evaluated. Micromorphology and microarea composition characterization of the filter element inner wall, as well as composition testing of detached particles, further demonstrates that the stainless steel particles responsible for valve sticking originate from inner-wall shedding of the filter element. Finally, the intrinsic sticking mechanism of the solenoid valve was systematically analyzed. Numerical results show that the maximum frictional resistance generated by a single hard particle is 0.034&#xa0;N, and particle accumulation exceeding 142 particles within the valve clearance will trigger solenoid valve sticking. This study provides a feasible diagnostic method and technical reference for similar solenoid valve faults, facilitating the prevention of sticking failures in EH system solenoid valves in practical engineering.</p>

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Root Cause Analysis of EH System Solenoid Valve Jamming Failure of Thermal Power Plant

  • 期刊论文

  • 发表日期：

    2026年6月2日

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  • Chudong Qin,
  • Shizhong He,
  • Xincong Zhou,
  • Qiuqiu Li,
  • Tao Gu,
  • Jun Liu,
  • Yuhang Luo,
  • Qiuying Li

摘要

The electro-hydraulic (EH) system is a critical subsystem of thermal power plant generating units, which regulates the opening of turbine steam valves via solenoid valves. Solenoid valve sticking failure poses a severe threat to the operational safety of generating units. In this study, macroscopic inspection, surface micromorphology analysis, metallographic testing, and hardness measurement were conducted on faulty solenoid valves. The results confirm that valve sticking is induced by three-body abrasive wear. Furthermore, particle composition analysis was performed on oil samples collected from both the EH system oil tank and faulty solenoid valves, verifying that the sticking-causing contaminants are stainless steel particles. Subsequently, the filtration performance of brand-new EH system filter elements was comprehensively evaluated. Micromorphology and microarea composition characterization of the filter element inner wall, as well as composition testing of detached particles, further demonstrates that the stainless steel particles responsible for valve sticking originate from inner-wall shedding of the filter element. Finally, the intrinsic sticking mechanism of the solenoid valve was systematically analyzed. Numerical results show that the maximum frictional resistance generated by a single hard particle is 0.034 N, and particle accumulation exceeding 142 particles within the valve clearance will trigger solenoid valve sticking. This study provides a feasible diagnostic method and technical reference for similar solenoid valve faults, facilitating the prevention of sticking failures in EH system solenoid valves in practical engineering.