【作者】 陈秀娟；

【导师】 唐贵基； 向玲；

【作者基本信息】 华北电力大学 ， 机械电子工程， 2011， 硕士

【摘要】 随着电力系统的发展,汽轮发电机组轴系扭振问题越来越突出。电力系统故障和运行方式改变都可能产生较大的电网冲击,激起机组轴系扭振。分析电网冲击下的机组轴系扭振响应特性对保证机组的安全运行有十分重要的意义。以东方300MW汽轮发电机组轴系扭振物理模拟机为研究对象,建立了模拟机轴系的多段集中质量模型。对Riccati传递矩阵法进行了改进,采用改进后算法和Holzer法计算了轴系扭振固有特性,结果与实测结果相吻合。采用Newmark-β增量法与Riccati传递矩阵法相结合求解轴系扭振响应。针对Newmark-β法在时间步长内的线性假设,提出消除线性累积误差的方法,建立了轴系扭振瞬态响应求解模型,得到模拟机在几种典型电网冲击下的扭振响应特性。分析结果表明:几种典型电网冲击均能不同程度激起轴系扭振固有频率;在整个轴系扭振响应上,发电机转子和低压缸转子处的响应较大,而发电机转子处最为严重;不能单纯确定哪种电网冲击引起轴系扭振的响应更大,响应的大小与轴段位置有关,应视不同轴段具体分析。论文分析了扭振机电系统的机、电、网各部分模型,建立扭振的机电统一模型。利用EMTP-RV仿真软件进行了电网冲击下的扭振响应仿真分析,所得响应结果与用Newmark-β增量法和Riccati传递矩阵相结合的方法计算结果吻合,为机组轴系扭振的进一步研究提供了理论依据。更多还原

【Abstract】 With the development of electric power, the problem of shaft Torsional Vibration on turbine generators has drawn broad attention. Power system fault and operating mode changes may have a greater impact on the power network. These conditions may result in shaft torsional vibration. So it is greatly practical and significant for safe and stable operation units to analyze the response characteristics of torsional vibration with power network impact.Taking an example of torsional vibration simulator on DongFang 300MW turbine generators, the multi-spring mass model of whose shaft is established. Then the inherent characteristics of shaft torsional vibraion are calculated by algorithm of improved Riccati traditional matrix and by that of Holzer. These tesults are consistent with the test results.A new method of Riccati traditional matrix combined with Newmark-βincremental method is put forward to solving shaft response of nonlinear torsional vibration system. But there will be a linear suppose in the time-step when using this method, a method is proposed to eliminate cumulate error from this suppose. Then another model for response of torsional vibration is established. On this model, the response characteristics of shaft torsional vibration are calculated and analyzed under several typical impacts of power network. Thus, we can conclude that from this paper, the response characteristics can be described as following: all these impacts can stimulate inherent frequencies on different degrees; for the whole shaft, the responses of low pressure cylinder rotor and of generator rotor are stronger, especially of generator rotor; the same section of shaft have different response to different impacts, so we can not simply to determine which impacts will cause a stronger response and should analyze problems depending on the actual situation.Torional electromechanical systems is composed of mechanic、electric and network. Submodels of every part are introduced in this paper, then the Model unified electric and mechanic is set up. On the EMTP-RV (which is an electro -magnetic transient simulation software), the typical power network impacts are simulated, and the response of shaft torsional vibration are gained again. The response results are consistent with above results used the new method. It provides a reference for further research on the actual units.更多还原