水力发电机组注意事项 Precautions for Hydroelectric Generating Units

首先发电机组的概念：发电机组是指能将机械能或其它可再生能源转变成电能的发电设备。一般我们常见的发电机组通常由以下几个：汽轮机、水轮机或内燃机（汽油机，柴油机等发电机）驱动、风能、太阳能、生物质能、海洋能等。柴油发电机的市场最大，主要是由于柴油发电机组的容量较大，可并机运行且持继供电时间长，还可独立运行，不与地区电网并列运行，不受电网故障的影响，可靠性较高。尤其对某些地区常用市电不是很可靠的情况下，把柴油发电机作为备用电源，既能起到应急电源的作用，又能通过低压系统的合理优化，将一些平时比较重要的负荷 在停电时使用。因此在工程中得到广泛的使用。

水力发电机组，是将水的势能转换为电能的机械设备。

水力发电机组的工作原理：河川、湖泊等位于高处具有势能的水流至低处，经水轮机转换成水轮机的机械能，水轮机又推动发电机发电，将机械能转换成电能。

水力发电机组中的水轮发电机由水轮机驱动。发电机的转速决定输出交流电的频率，因此稳定转子的转速对保证频率的稳定至关重要。可以采取闭环控制的方式对水轮机转速进行控制，即采取发出的交流电的频率信号样本，将其反馈到控制水轮机导叶开合角度的控制系统中从而去控制水轮机的输出功率，以达到让发电机转速稳定的目的。

注意事项: 

水力发电机组是实现水的位能转化为电能的能量转换装置，一般由水轮机、发电机、调速器、励磁系统、冷却系统和电站控制设备等组成。

（6）电站控制设备：电站控制设备主要以微机为主，实现水力发电机的并网、调压、调频、功率因数的调节、保护和通信等功能。

（7）制动装置：额定容量超过一定值的水力发电机均设有制动装置，其作用是在发电机组停机过程中，当转速降低到额定转速的30%～40%时，对转子实施连续制动，以避免推力轴承因低转速下油膜被破坏而烧损轴瓦。制动装置的另一作用是在安装、检修和起动前，用高压油顶起发电机的旋转部件。制动装置采用压缩空气进行制动。

Firstly, the concept of a generator set: A generator set refers to a power generation equipment that can convert mechanical energy or other renewable energy into electrical energy. The commonly used generator sets are usually driven by the following: steam turbine, water turbine, or internal combustion engine (gasoline engine, diesel engine, etc.), wind energy, solar energy, biomass energy, ocean energy, etc. The market for diesel generators is the largest, mainly due to the large capacity of diesel generator sets, which can operate in parallel and maintain power supply for a long time. They can also operate independently and are not parallel to the regional power grid. They are not affected by power grid failures and have high reliability. Especially for some areas where the commonly used mains power is not very reliable, using diesel generators as backup power sources can not only serve as emergency power sources, but also optimize the low-voltage system to use some important loads during power outages. Therefore, it has been widely used in engineering.

A hydroelectric generator set is a mechanical device that converts the potential energy of water into electrical energy.

The working principle of a hydroelectric generator set: Rivers, lakes, and other areas with potential energy flow from high places to low places, which are converted into mechanical energy by a water turbine. The water turbine then drives a generator to generate electricity, converting the mechanical energy into electrical energy.

The hydroelectric generator in a hydroelectric power unit is driven by a water turbine. The speed of the generator determines the frequency of the output AC power, so stabilizing the rotor speed is crucial to ensuring frequency stability. The speed of the water turbine can be controlled by closed-loop control, which takes the frequency signal samples of the generated AC power and feeds them back to the control system that controls the opening and closing angle of the turbine guide vanes to control the output power of the water turbine, in order to achieve the goal of stabilizing the generator speed.

matters needing attention:

A hydroelectric generator set is an energy conversion device that converts the potential energy of water into electrical energy. It generally consists of a water turbine, generator, speed controller, excitation system, cooling system, and power station control equipment.

(1) Water turbine: There are two commonly used types of water turbines: impulse type and counterattack type.

(2) Generator: Most generators use synchronous generators with low speeds, generally below 750r/min, and some only have a few tens of revolutions per minute; Due to the low rotational speed, there are more magnetic poles; The structural dimensions and weight are both relatively large; There are two installation forms for hydroelectric power units: vertical and horizontal.

(3) Speed regulation and control device (including speed regulator and oil pressure device): The function of the speed regulator is to regulate the speed of the water turbine to ensure that the frequency of the output electrical energy meets the power supply requirements, and to achieve unit operation (start-up, shutdown, speed change, load increase and decrease) and safe and economical operation. Therefore, the performance of the governor should meet the requirements of fast operation, sensitive response, rapid stability, easy operation, and maintenance. It also requires reliable manual operation and emergency shutdown devices.

(4) Excitation system: Hydroelectric generators are generally electromagnetic synchronous generators. By controlling the DC excitation system, voltage regulation, active power and reactive power can be achieved to improve the quality of output electrical energy.

(5) Cooling system: The cooling of small hydroelectric generators mainly adopts air cooling, which cools the stator, rotor, and iron core surfaces of the generator through a ventilation system. But with the increase of single machine capacity, the thermal load of the stator and rotor continues to increase. In order to improve the output power per unit volume of the generator at a certain speed, large capacity hydroelectric generators adopt direct water cooling of the stator and rotor windings; Alternatively, the stator winding can be cooled with water, while the rotor can be cooled with strong wind.

(6) Power station control equipment: The power station control equipment mainly uses microcomputers to achieve functions such as grid connection, voltage regulation, frequency regulation, power factor adjustment, protection, and communication of hydraulic generators.

(7) Braking device: Hydroelectric generators with a rated capacity exceeding a certain value are equipped with braking devices. Their function is to continuously brake the rotor when the speed drops to 30% to 40% of the rated speed during the shutdown process of the generator set, in order to prevent the thrust bearing from burning the bearing due to oil film damage at low speeds. Another function of the braking device is to use high-pressure oil to lift the rotating parts of the generator before installation, maintenance, and starting. The braking device uses compressed air for braking.