After-sales review: Solving the problems of oscillation and out-of-synchronization of synchronous generator sets

Jiangsu Haixing Power reviewed the after-sales service information in 2010 and found that some customers were synchronizingGenerator setFailure to detect problems in time when oscillation and out-of-synchronization occur may result in damage to the unit. So, HaixingGenerator setGuide you to determine which generator is out of step from the indications of the meter, so as to solve the problem and ensure the smooth operation of the unit.

Dealing with accidents is generally divided into three steps. We need to understand the essence of the problem: What is the reason for the oscillation and loss of synchronization of the generator set?
As we all know, when a synchronous generator is operating normally, the rotational speed of the rotor and the synchronous rotational speed of the stator magnetic field are in a synchronized state. However, when the load suddenly changes, due to the effect of rotor inertia, the rotor displacement cannot immediately stabilize at the new value, but will cause several swings around the new stable value. This phenomenon is the oscillation of the synchronous generator. When oscillation occurs When the speed of the unit is no longer consistent with the synchronous speed of the stator magnetic field, the generator and the power system will operate out of sync. This phenomenon is the desynchronization of the synchronous generator.

So, how should we observe the problem of generator set losing synchronization? Oscillation or out-of-step can be seen from the indication of the meter, which can be divided into the following steps:
(1) The pointer of the stator ammeter swings violently, and the current may exceed the normal value;
(2) The pointers of the generator voltmeter and other bus voltmeters swing violently and often decrease;
(3) The pointer of the active power meter swings at full scale;
(4) The pointer of the rotor ammeter swings near the normal value.
However, in the event of an accident, the meters of each motor running in parallel are often swinging, which can be distinguished from the following aspects:
(1) In case of out-of-step caused by an accident in our factory, we can always determine which relevant unit may be out-of-step based on the operating reasons or fault location of our factory;
(2) Generally speaking, the meter swing range of out-of-step motors is greater than that of other motors;
(3) The active power meter of the out-of-step motor swings at full scale, and even hits the needle stops on both sides, while other units swing around the normal load value, and when the needle of the active power meter of the out-of-step motor swings to zero or When it is negative, the hands of other motors will swing to the side with the larger positive indication value, that is, the two swing directions are exactly opposite.
If an oscillation tends to be stable, that is, the smaller the oscillation, the smaller the oscillation, then there is no need to do anything. The oscillation will pass after a few times. Just be mentally prepared to deal with the accident.

As long as we take measures to solve the out-of-sync situation, we can create the conditions to restore synchronization as soon as possible:
(1) Increase the excitation of the generator;
(2) If a motor loses synchronization, its active output can be appropriately reduced;
(3) According to the above method, if the synchronization state has not been entered after 1-2 minutes, the out-of-step motor can be decoupled from the system.