The reverse power protection of diesel generator is used to protect the steam turbine. When the main steam valve is closed by mistake or the turbine boiler protection action closes the main steam valve and the outlet switch of the generator does not trip, the generator becomes the motor running state. At this time, the generator absorbs active and reactive power from the system. This working condition has no impact on the generator. However, due to the loss of blast, the tail blade of the gas turbine may overheat and damage the tail blade, resulting in steam turbine accident. Therefore, large units are not allowed to operate for a long time under this condition, only for a few minutes.

我國自行設(shè)計的發(fā)電機，以往不裝設(shè)逆功率保護，但采取以下措施：

In the past, generators designed by our country were not equipped with reverse power protection, but the following measures were taken:

(1)采用聯(lián)鎖方法。當主汽門關(guān)閉后，用主汽門輔助接點，經(jīng)延時切除發(fā)電機。上述方法雖然可行，但有不足之處，因為都不能正確地反映主汽門關(guān)閉情況。為了及時發(fā)現(xiàn)逆功率的異常工況，歐洲一些國家在發(fā)電機上配置有逆功率保護。逆功率保護其核心元件是逆功率繼電器。逆功率繼電器和功率方向繼電器相似，只是在功率方向相反時動作，及時發(fā)出信號或延時動作切機。

(1) Adopt interlocking method. When the main throttle valve is closed, use the auxiliary contact of the main throttle valve to cut off the generator after delay. Although the above methods are feasible, they have shortcomings, because they can not correctly reflect the closing condition of main steam valve. In order to find the abnormal working condition of reverse power in time, some European countries have configured reverse power protection on generators. The core component of reverse power protection is reverse power relay. The reverse power relay is similar to the power direction relay, but acts when the power direction is opposite, sends a signal in time or delays the action to cut off the machine.

(2)主汽門關(guān)閉后，在控制室內(nèi)發(fā)信號，如主汽門誤關(guān)閉，檢查之后可迅速恢復供汽，使機組正常運行，如幾分鐘恢復不了，可由值班員斷開發(fā)電機出口開關(guān)。

(2) After the main throttle valve is closed, send a signal in the control room. If the main throttle valve is closed by mistake, the steam supply can be quickly restored after inspection to make the unit operate normally. If it cannot be restored in a few minutes, the operator on duty can turn off the outlet switch of the development motor.

1．供油時間過早

1. The oil supply time is too early

當柴油發(fā)電機活塞向上運動還沒達到規(guī)定的噴油位置，噴油器就開始噴油，使燃油燃燒提前，氣缸內(nèi)的高壓燃氣沖擊活塞，發(fā)出有節(jié)奏的“嗒、嗒”的清脆敲缸聲，減小油門，敲缸聲很明顯。

When the piston of the diesel generator moves upward and hasn't reached the specified injection position, the fuel injector starts to inject fuel to advance the fuel combustion. The high-pressure gas in the cylinder strikes the piston and makes a rhythmic "Da, Da" crisp cylinder knocking sound. Reduce the throttle and the cylinder knocking sound is obvious.

排除方法是：調(diào)整供油提前角，即增加噴油泵與齒輪箱之間的墊片使供油時間延遲至符合規(guī)定的噴油時間。墊片每增加0.1毫米，供油提前角可延遲1.3-1.7。

The troubleshooting method is: adjust the fuel supply advance angle, that is, increase the gasket between the fuel injection pump and the gearbox to delay the fuel supply time to the specified fuel injection time. The oil supply advance angle can be delayed by 1.3-1.7 for every 0.1mm increase in the gasket.

2．燃油燃燒不良

2. Poor fuel combustion

噴油壓力過低、噴油器滴油、噴油霧化不良以及供油時間過晚等都會造成燃油燃燒不良而引起敲缸。這類故障引起的敲缸聲低沉、沙啞并伴有發(fā)動機過熱、冒黑煙或排氣管放炮、噴火等現(xiàn)象。應(yīng)拆下噴油器進行檢查和調(diào)整、調(diào)整供油時間，必要時更換零件，使之符合規(guī)定。

Low fuel injection pressure, fuel injector dripping, poor fuel injection atomization and too late fuel supply time will cause poor fuel combustion and cylinder knocking. The cylinder knocking caused by this kind of fault is low and hoarse, accompanied by engine overheating, black smoke or exhaust pipe blasting, fire spraying and other phenomena. The fuel injector shall be removed for inspection and adjustment, the fuel supply time shall be adjusted, and the parts shall be replaced if necessary to make it meet the regulations.

3．出油閥門磨損

3. The oil outlet valve is worn

出油閥磨損后，一方面使減壓環(huán)帶與閥座內(nèi)孔配合間隙變大，密封性變差、減壓效果變壞；另?方面高壓油管內(nèi)剩余壓力過高，供油增加，引起燃油爆燃而敲缸．油門減小時敲缸聲尤為明顯。

After the oil outlet valve is worn, on the one hand, the fit gap between the pressure reducing ring belt and the inner hole of the valve seat becomes larger, the tightness becomes worse and the pressure reducing effect becomes worse; Another? On the one hand, the residual pressure in the high-pressure oil pipe is too high and the oil supply increases, resulting in fuel deflagration and cylinder knocking. The cylinder knocking sound is particularly obvious when the throttle is reduced.

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