燃氣-蒸汽聯(lián)合循環(huán)發(fā)電機組是當前技術成熟的潔凈型商業(yè)發(fā)電裝置，目前最先進機組的發(fā)電效率已達60%。所謂單軸，是指燃氣輪機、蒸汽輪機和發(fā)電機同在一根軸上。其中，西門子和阿爾斯通（被GE收購)的單軸機組中蒸汽輪機和燃氣輪機及發(fā)電機之間設有連軸器，當汽輪機轉速小于發(fā)電機轉速時連軸器將自動脫開;通用電氣和三菱的單軸機組則是剛性連接的。

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

即配置一臺燃機、(一臺燃機發(fā)電機)、一臺余熱鍋爐和一臺蒸汽輪發(fā)電機機組。單軸或多軸。

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

即配置二臺燃機、二臺燃機發(fā)電機、二臺余熱鍋爐和一臺蒸汽輪發(fā)電機機組。

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

單循環(huán)燃機做功，帶動燃機發(fā)電機發(fā)電，無余熱鍋爐。聯(lián)合循環(huán)

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

燃機及發(fā)電機、余熱鍋爐、蒸汽輪發(fā)電機組。

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

1、聯(lián)合循環(huán)機組電氣安裝的特點

1. Characteristics of Electrical Installation for Combined Cycle Units

若聯(lián)合循環(huán)機組采用多軸布置，則燃機和汽輪機分別配置一臺發(fā)電機。也就是說在一套聯(lián)合循環(huán)機組中要進行兩套發(fā)電機/變壓器的安裝、兩套PT/CT的安裝、兩套出線和封閉母線安裝、兩套發(fā)變組保護的安裝和調試。相對應的發(fā)電機附屬設備和消防設施等都是雙倍的，安裝工作量遠大于同樣容量的常規(guī)火電機組。

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啟動方式。聯(lián)合循環(huán)電廠的起動是從燃氣輪機開始，燃氣輪機是將發(fā)電機用作電動機起動的，電網的供電經變頻器轉變成變頻電源，用來驅動發(fā)電機。在起動程序開始之前，循環(huán)水系統(tǒng)、冷卻塔、閉路冷卻水系統(tǒng)和壓縮空氣系統(tǒng)等輔機系統(tǒng)先投入運行。當燃氣輪機達到10%額定轉速時(此時稱為點火轉速)，供入燃料氣并開始點火，使燃氣輪機加速直到燃機可以維持的轉速(此時稱為自持轉速)。

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).

這時，關斷供向發(fā)電機的變頻電源，燃氣輪機繼續(xù)加速，直至額定轉速。燃氣輪機起動后不久，透平的排氣便開始加熱余熱鍋爐。余熱鍋爐沒有燃氣輪機的排氣旁通煙囪，也不供應輔助蒸汽，所以，整個系統(tǒng)必須同時起動。這就是燃機的SFC啟動，也就是利用發(fā)電機作為啟動馬達，為此，電氣在勵磁系統(tǒng)中需要配備一套大功率的變頻裝置.(在啟動和發(fā)電過程要完成恒流/恒壓轉換)

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: http://www.dgtmcnc.com I hope this article can be helpful to you. Thank you for reading!