水轮发电机的机械特性

方向属于Rotation

旋转方向发电机should suit the prime mover requirements.

大型发电机定子

The stator frame is designed for rigidly and strength to allow it to support the clamping forces needed to retain the stator punching in the correct core geometry. Strength is needed for the core to resist deformation under fault conditions and system disturbances. Also, the core is subjected to magnetic forces that tend to deform it as the rotor field rotates. In some large size machines, this flexing has been known to cause the core to contact the rotor during operation. In one instance, the core deformed and contacted the rotor, the 218 machine was tripped by a ground fault, and intense heating caused local stator tooth iron melting, which damaged the stator winding ground insulation. In machines with split phase windings where the split phase currents are monitored for machine protection, the variation in the air gap causes a corresponding variation in the split phase currents. If the variations are significant, the machine will trip by differential relay action, or the differential relays will have to be desensitized to prevent tripping. Desensitizing the relays will work, but it reduces their effectiveness in protecting the machine from internal faults.

Rotor Assembly Critical Speeds

A rotor dynamic analysis of the entire shaft system should be performed. This analysis should include the prime mover, generator, and any other rotating components. This analysis should include lateral and torsional shaft system response to the various excitations that are possible within the operational duties allowed by the standards. When theturbine发电机是成套购买的，通常制造商应进行此分析。当从不同制造商处购买轴部件时，买方应安排进行此分析。发电机转子组件的临界转速不应在与按照9.3.1.4商定的频率范围相对应的速度范围内导致不合格的运行。发电机转子组件还应在静止和原动机和发电机设计师商定的额定速度之间的速度下，在合理的时间内正常运行。水轮发电机组在运行速度下的轴振动应在ISO:7919-5规定的水力发电和抽水设备机组的限值内。

轴承

The allowable hydraulic thrust provided in standard generator design is satisfactory for use with a Francis runner, but a Kaplan runner requires provision for higher-than-normal thrust loads. It is important that the generator manufacturer have full and accurate information regarding the turbine. Specifications for generators above 10 MW, and for generators in unmanned plants, should require provisions for automatically pumping oil under high pressure between the shoes and the runner plate of the thrust bearing just prior to and during machine startup, and when stopping the machine.

噪声级和振动

在所有的操作条件下,噪声水平发电机should be less than 85-95 dB (A) at a distance of 1 meter radialy & 1.5 m from floor of operating. In order to prevent undue and harmful vibrations, all motors should be statically and dynamically balanced in accordance with IEEE std. C50.12-2005. Test procedure for verification should be based on ISO 3746. Acoustic treatment may be necessary to achieve decreasing sound pressure levels at 90 db.

超速耐受

It is general practice in India to specify allhydro发电机应设计用于全涡轮失控条件（IS:4722-2001，表3第1条）。设计飞逸转速下的应力不应超过屈服点的三分之二。根据陆军工程设计手册，美国惯例如下：低于360rpm和50000 kVA及以下的发电机通常设计为100%超速。

Flywheel Effect

机器的飞轮效应（WR2）表示为旋转部件的重量乘以回转半径的平方。发电机的WR2可通过增加转子轮缘的重量或增加转子直径来增加。增加WR2会增加发电机的成本、尺寸和重量，并降低效率。必须从对电力系统稳定性的影响和对机组调速的影响两个角度分析是否需要高于正常值的WR2。速度调节和调速器计算在涡轮机和调速器。电气系统稳定性考虑在特殊情况下可能要求较高的WR2只是影响系统稳定性的几个可调因素之一，为了达到最低的总成本，系统设计中的所有因素都应该被考虑。必须提供足够的WR2，以防止蛇行，并在负载突然变化时提供稳定性。电力系统计算中使用的发电机的相对稳定性指数是惯性常数H，用每千伏安容量的储存能量表示。计算如下：BETVICTRO伟德

H =kVAkW • s=kVA0.231(WR2 )(r/min)2 ×10−6

低速（低于200 rpm）水轮机的惯性常数在2到4之间发电机。瞬态系统要求的水力研究提供了有关最佳惯性常数的最佳信息，但如果研究数据不可用，必要的WR2可以计算，也可以根据系统上其他单元的行为的知识进行估计。与飞轮效应WR2相比，飞轮效应用惯性矩（GD2）（在印度）表示

（美国/英国）GD2=重量x直径2和WR2=重量x半径2(磅英尺2). 相应地，WR2=4 GD2换算系数，适用于WR2（美国）磅英尺2和GD2（印度）公斤。m2如下：

GD2 = x×5.9=lb. ft 2 ≈6 x lb. ft 2

飞轮效应属于the generator can be increased by adding weight in the rim of the rotor or by increasing the rotor diameter. Increasing the GD2 increases the generator cost, size and weight, and lowers the efficiency. The need for above-normal WR2 / GD2 is analyzed from two standpoints, the effect on power system stability, and the effect on speed regulation of the unit. Speed regulation and governor calculation are discussed in guidelines for turbine selection. Power system stability considerations do not arise in small hydro generators under considerations.

Mechanical发电机的特性基于发电机将与之耦合的水轮机数据。Characteristicsregarding speed, flywheel effect have been discussed in guidelines of turbine selection.

Cooling

Losses in a generator appear as heat which is dissipated through radiation and ventilation. The generator rotor is normally constructed to function as an axial flow blower, or is equipped with fan blades, to circulate air through the windings. Small-generators up to 5 MW may be partially enclosed, and heated generator air is discharged into the generator hall, or ducted to the outside. Adequate ventilation of the generator hall preferably thermostatically should be provided in this case.

额定值大于5 MVA的所有现代水轮发电机通常配备水-空冷却器。冷却器位于定子铁芯的外周。配备水-空气冷却器的发电机可以设计成更小的物理尺寸，从而降低发电机的成本。提高发电机定子绕组的运行温度，直接关系到发电机的运行寿命。该系统可以更容易地控制发电机的冷却，保持定子绕组和铁芯通风槽的清洁，降低了定子绕组绝缘系统的劣化率。关闭

systems also permits the addition of automatic fire protection systems, attenuates generator noise, and reduce heat gains that must be accommodated by the powerhouse HVAC system. Normally, generators should be furnished with one cooler than the number required for operation at rated MVA. This allows one cooler to be removed for maintenance without affecting the unit output.The generator cooling water normally is supplied from the penstock via a pressure reducing station or pumped from the tailrace. In either case, automatic self-cleaning filters must be provided in the cooling water supply lines to avoid frequent fouling or plugging of the water-to-air coolers.

灭火系统

All hydroelectric generators greater than 25 MVA should be furnished with either a water deluge or carbon dioxide (CO2) fire extinguishing system, to minimize the damage caused by a fire inside the machine. Generators 25 MVA or below should be evaluated individually to ensure installation of a cost effective system. When total thermo setting insulation system is adopted water sprinkler system may be used. This system is safer for operating staff.

High Pressure Oil Injection System (For Thrust Bearing)

Modern Thrust Bearings have a high-pressure oil lift system, which injects oil into each shoe pad of the bearing during starting and stopping of the unit. This helps establish a hydrodynamic oil film between the rotating (thrust collar) and stationary (bearing shoes or pads) members of the thrust bearing. The presence of the hydrodynamic oil film minimizes bearing wear. Consequently, during a unit start the high pressure oil of lift system is turned on before the unit starts to rotate. It is usually shut off after the unit speed exceeds 75 to 90% of rated speed because, at the higher rotational speeds, the hydrodynamic oil film is self sustaining. On unit shutdown, the high pressure oil lift system is turned on when the unit speed decreases to the 75 to 90% range and maintained until the unit is at stand still. The maximum wear on the bearing pads occurs at slow speeds, when, due to hydrodynamic effects, the oil film is not maintained over the entire bearing surface.

Dynamic Braking System

Modern hydroelectric generators use electrical dynamic braking in addition to the mechanical friction braking system. The electrical dynamic braking system minimizes the wear on the mechanical brake ring and brake pads, prolonging their life. In addition, electrical dynamic braking reduces the duration over which the mechanical brakes are applied during a unit stop sequence, thereby minimizing the amount of brake dust produced by the mechanical brake system. The extended life and reduced brake dust are especially significant for units that are started and stopped several times a day; or units; such as those connected to pelton turbines, which operate at very high rpms.

电动力制动在较高的单位转速下启动，通常为额定转速的50%；并保持到机械摩擦制动器接合。当动态制动与机械制动器一起使用时，机械制动器通常以额定速度的10%至15%施加。现代水力发电机组，尤其是抽水蓄能机组，也利用制动器粉尘真空系统来收集机械摩擦制动器应用时产生的大部分制动器粉尘。