What is the cause of the trip in the alternator?
The alternator has tripped during use, so what is the cause? The following alternator Xiaobian introduces you.
1. When the generator-transformer group main breaker automatically trips, first check whether the generator indicator has obvious fault symbol. If it is time to cut off the excitation immediately, if there is no abnormality, if the furnace is in good condition, The electric duty attendant should adjust the generator voltage and frequency within the normal range. It should check whether the high-voltage power supply of the unit is tripped, whether the startup is connected or not, and whether the power consumption of the plant is normal.
2. According to the accident phenomenon and the relay protection action, judge the nature and scope of the fault, and make detailed external inspection of the generator-transformer group and related equipment to find out whether there is external fault feature.
3. If the generator is protected due to the mother-slip protection action or the over-current protection of the generator due to the fault of the substation, check the generator externally. After the fault is isolated, contact the network to connect to the grid.
4. Before the trip, if there is strong excitation action, there is current impact, which reflects the main protection (differential, heavy gas, etc.) action of the internal fault of the generator-transformer group, and the grid runs normally.
5. If there is no strong excitation action before tripping, there is no inrush current, the grid operation is normal, the furnace is normal, the generator's water-hydrogen oil system and main transformer are normal, and the following treatment is performed: check the generator and its circuit; The protection of the action is checked, as all normal generators can be boosted from zero. If everything is normal during boosting, the generator can be connected to the grid and continue to find the cause. When boosting, the strong excitation and automatic adjustment device shall not be put into operation. The neutral point of the high-voltage side of the generator-transformer group shall be grounded. If abnormality is found, stop the inspection immediately.
Due to the complicated setup of the alternator, many available protection methods are used, which makes the alternator better.
1, vector magnetic protection
The vector magnetic protection acts as the sagittal magnetic fault protection that the generator excitation current drops abnormally or completely disappears. The excitation low voltage UFD(P), system low voltage, static and stable impedance, TV disconnection and other criteria are automatically set by the setting value. , respectively, acting on signalling and de-arcing. Both the excitation low voltage criterion and the static and stable impedance criterion are related to the static stability boundary to detect whether the alternator is magnetically deformed and lose static stability. The static impedance criterion operates when the boundary is statically stabilized after the vector.
2, magnetic protection
Reflecting the protection of the alternator due to the lowering of the generator frequency or the excessive voltage
3, stator protection (grounding, daytime)
The motor stator single-phase ground fault protection consists of a fundamental zero-sequence voltage and a third-order harmonic voltage. The turn-to-turn protection consists of the longitudinal zero-sequence voltage and the fault negative sequence direction criterion, and the PT disconnection blocking measure is set as the internal turn-to-turn protection of the generator.
4, the rotor a little, two points grounding protection
It is used for the generator rotor circuit to detect the positive and negative ground voltages of the sampling loop, and calculate the rotor grounding resistance in real time.
5, differential protection
The main protection of the main circuit of the generator is the overcurrent protection caused by the short circuit between the power grid and the generator itself.
6, overload protection
Time-delay and inverse time-limit, the ability of the generator to withstand the load current and the heat build-up of the engine stator