燃气-蒸汽联合循环发电机组是当前技术成熟的洁净型商业发电装置，目前最先进机组的发电效率已达60%。所谓单轴，是指燃气轮机、蒸汽轮机和发电机同在一根轴上。其中，西门子和阿尔斯通（被GE收购)的单轴机组中蒸汽轮机和燃气轮机及发电机之间设有连轴器，当汽轮机转速小于发电机转速时连轴器将自动脱开;通用电气和三菱的单轴机组则是刚性连接的。

Gas steam combined cycle power generation units are currently mature and clean commercial power generation devices, and the power generation efficiency of the most advanced units has reached 60%. The so-called single shaft refers to the gas turbine, steam turbine, and generator being on the same shaft. Among them, Siemens and Alstom (acquired by GE) have a coupling between the steam turbine, gas turbine, and generator in their single shaft units. When the turbine speed is lower than the generator speed, the coupling will automatically disconnect; The single axis units of General Electric and Mitsubishi are rigidly connected.

一拖一

One drag one

即配置一台燃机、(一台燃机发电机)、一台余热锅炉和一台蒸汽轮发电机机组。单轴或多轴。

Configure one gas turbine, one gas turbine generator, one waste heat boiler, and one steam turbine generator unit. Single axis or multi axis.

二拖一

Two drag one

即配置二台燃机、二台燃机发电机、二台余热锅炉和一台蒸汽轮发电机机组。

Configure two gas turbines, two gas turbine generators, two waste heat boilers, and one steam turbine generator unit.

单循环燃机做功，带动燃机发电机发电，无余热锅炉。联合循环

A single cycle gas turbine does power, drives the gas turbine generator to generate electricity, without a waste heat boiler. combined cycle 

燃机及发电机、余热锅炉、蒸汽轮发电机组。

Gas turbine and generator, waste heat boiler, steam turbine generator set.

1、联合循环机组电气安装的特点

1. Characteristics of Electrical Installation for Combined Cycle Units

若联合循环机组采用多轴布置，则燃机和汽轮机分别配置一台发电机。也就是说在一套联合循环机组中要进行两套发电机/变压器的安装、两套PT/CT的安装、两套出线和封闭母线安装、两套发变组保护的安装和调试。相对应的发电机附属设备和消防设施等都是双倍的，安装工作量远大于同样容量的常规火电机组。

If the combined cycle unit adopts a multi shaft layout, the gas turbine and steam turbine are respectively equipped with one generator. That is to say, in a combined cycle unit, two sets of generators/transformers, two sets of PT/CT, two sets of outgoing lines and enclosed busbars, and two sets of generator transformer protection installation and commissioning need to be carried out. The corresponding generator ancillary equipment and fire protection facilities are double, and the installation workload is much greater than that of conventional thermal power units with the same capacity.

SFC启动方式。联合循环电厂的起动是从燃气轮机开始，燃气轮机是将发电机用作电动机起动的，电网的供电经变频器转变成变频电源，用来驱动发电机。在起动程序开始之前，循环水系统、冷却塔、闭路冷却水系统和压缩空气系统等辅机系统先投入运行。当燃气轮机达到10%额定转速时(此时称为点火转速)，供入燃料气并开始点火，使燃气轮机加速直到燃机可以维持的转速(此时称为自持转速)。

SFC startup method. The start-up of a combined cycle power plant starts with a gas turbine, which uses the generator as an electric motor for starting. The power supply from the grid is converted into a variable frequency power supply through a frequency converter to drive the generator. Before starting the program, auxiliary systems such as the circulating water system, cooling tower, closed-loop cooling water system, and compressed air system should be put into operation. When the gas turbine reaches 10% of the rated speed (referred to as ignition speed), fuel gas is supplied and ignition begins, causing the gas turbine to accelerate until it can maintain a speed (referred to as self-sustaining speed).

这时，关断供向发电机的变频电源，燃气轮机继续加速，直至额定转速。燃气轮机起动后不久，透平的排气便开始加热余热锅炉。余热锅炉没有燃气轮机的排气旁通烟囱，也不供应辅助蒸汽，所以，整个系统必须同时起动。这就是燃机的SFC启动，也就是利用发电机作为启动马达，为此，电气在励磁系统中需要配备一套大功率的变频装置.(在启动和发电过程要完成恒流/恒压转换)

At this point, turn off the variable frequency power supply to the generator, and the gas turbine continues to accelerate until the rated speed is reached. Shortly after the start of the gas turbine, the exhaust of the turbine begins to heat the waste heat boiler. The waste heat boiler does not have a gas turbine exhaust bypass chimney and does not supply auxiliary steam, so the entire system must be started simultaneously. This is the SFC starting of the gas turbine, which uses the generator as the starting motor. Therefore, the electrical system needs to be equipped with a high-power variable frequency device in the excitation system (Complete constant current/constant voltage conversion during startup and power generation)

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This article is provided with assistance from gas generator set accessories. For more related content, please click: https://www.huannengpower.cn I hope this article can be helpful to you. Thank you for reading!