柔性运行对水轮发电机的影响

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柔性运行对水轮发电机的影响

日期:

2021年12月13日

BY:

Davi Squaiella, Senior Generator Electrical Engineer, 黑色的 & Veatch

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柔性运行对水轮发电机的影响

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随着间歇性可再生能源的普及, the number of hydro units moving from base load into flexible operation increases every year. This new operation mode requires frequent starts/stops 和 load changes 和 brings new mechanical challenges for these units with impact to reliability 和 cost of generation. 黑色的 & Veatch has the expertise to evaluate potential risks 和 propose solutions to protect or maintain Owner’s equipment operating in this new regime with a focus on avoiding future forced outages.

转子

转子部件受低周疲劳的影响较大, 包括转子支架, rim, 波兰人, 磁场绕组, 和制动系统.

The 磁场绕组 presents the most common failure mode due to thermal expansion. This coupled with rotor rim growth from centrifugal force leads to fatigue cracking of the connections. A site assessment 和 fatigue analysis can provide a detailed design evaluation that will help identify 和 prevent such failure.

Poles fixed into the rotor rim are susceptible to cracks from significant stresses imposed during cyclic operation. An experienced engineer can perform an FEA that would evaluate the risk of catastrophic failure due to crack expansion.

Designs prior to the 1960’s may have the rotor rim integrally cast with the spider sometimes even with the pole bodies included – 和 are subject to high hoop tensile force on its structure due to centrifugal forces.

启动和停止也会影响制动系统——千斤顶, 刹车垫, 和 brake rings – with cracking in rotor brake rings 和 wear 和 tear of the 刹车垫. Most hydro units were originally designed for one stop every several months or even once a year. Flexible operation sometimes requires the brake system to be used several times each day. This greatly increases the wear 和 reduces the useful life of the brake systems.

在开始和停止之上, load changes 和 partial load increase vibrations that impact the bearings 和 cause fatigue 和 wear of all rotor components.

定子

定子组件也受到启动/停止的影响. 虽然具体的影响可能不太明显, they are primarily affected by temperature change during cyclic operation.

在岩心上劈开, temperature changes from cold to hot with each cycle can cause shifting of the core sections. Displacement can occur at the core split at the bottom of the slot, 给这个槽里的线圈带来了巨大的压力. Depending on the core fixation into the frame, waviness 和 buckling may also occur.

The most common failure mode on this component is the stator winding main insulation damage leading into ground short. 经过几个热循环, 定子绕组可能出现内部分层, creating voids 和 increasing partial discharges that reduces the component service life. A dedicated Inner Corona Protection (ICP) can prevent this failure mode.

Core hot spots at splits require special attention 和 should be tested with a core loop test at full induction levels. An EL-CID test should also be considered to detect shorted core laminations.

Recent studies show that stator windings have a potential service life reduction from 5 up to 10 service hours for every new starting cycle.

布莱克和维奇能帮上忙

灵活的操作给黑色的带来了挑战 & Veatch 理解. 适当的评估和 评估OEM图纸和文件, failure modes can be detected in the inception phase leading to optimal solutions that reduce the risk for forced outages.

电磁与机械有限元分析(Ansys), 专利分析工具, 和来自原始设备制造商的高水平的专业知识, 黑色的 & Veatch can provide specific components analysis with focus on reducing service life impact due to special operation conditions.

The main goal when evaluating components under flexible operation mode is to identify risks by means of FEA, 疲劳评估, 振动的调查, 转子动力学和适用性分析. 黑色的 & Veatch is able to analyze the effected components 和 determine how the potential failure mode – cracks or other indications – impacts the safety margin against short-term fracture 和 long-term fatigue.

Even when additional capacity is available for the unit’s uprate, flexible operation mode brings additional challenges into this scenario. Common questions before the uprate approach are: “What is the maximum power that can be extracted from the available water flow?” 和 “What must be done with the powertrain 和 balance of
plant to achieve this maximum power under flexible operation mode?“黑 & Veatch可以对发电机进行完整的分析, 轴, 励磁系统, 发电机机电元件, 升压变压器, 电源总线, 冷却系统, 定子谐波, 和 rotor dynamics in order to validate the uprate study within this special operation condition.

了解更多beat365app下载布莱克的信息 & Veatch’s experience on flexible operation conditions visit: www.bv.com/hydro