Solar Energy Photovoltaic Energy Solar Panel Power Generation Contractor

Our company strives to realise products diversification and differentiation, and to build the leading enterprise in the Bleed Condensing Steam Turbine, Condenser, Coal-fired Steam Boiler industry. So far our merchandise have been exported foreign countries. We relentlessly pursue technology and service innovation to provide customers with the highest quality products and comprehensive solutions. We believe that customer satisfaction is both the starting point and the foothold of our products and services.

Generator is not connected to the grid at the same time

The requirement of generator grid connection is that the voltage, frequency, phase sequence and phase are consistent before it can be connected to the grid. However, in some cases, due to the customer's failure of nuclear phase or the failure of synchronous devices, the generator is not connected to the grid at the same time, causing serious damage to the generator set and power system. The stator of non-synchronous grid-connected generator has a huge current impact, and the stator ammeter swings violently, so does the stator voltmeter. The huge current has a serious impact on the generator, transformer and system. Strong vibration will occur in the unit, which will cause the generator winding to deform, bend, break the insulation, melt the parallel sleeve of the stator winding, and cause serious hidden danger and even burn the winding. As far as the whole power system is concerned, if a large unit is connected to the grid at different times, the power of this generator will fluctuate with the system, seriously disrupting the normal operation of the whole system and even causing the collapse of the whole power system.

Generator short circuit, insulation breakdown

The frequent insulation breakdown faults of generators include phase-to-phase short circuit, turn-to-turn short circuit and ground fault.

Phase-to-phase short circuit: if the generator is short-circuited in two or three phases, the differential protection will trip, and the winding end of the generator will be subjected to a great impact of electromotive force, which may cause deformation of the coil end;

Turn-to-turn short circuit: the phenomenon of generator outgoing line shooting will melt the stator copper wire for a long time, and the three-phase voltage of the generator will be unbalanced when there is no load;

Ground fault: the breakdown position of the generator is in the straight line or notch position, and the stator grounding protection acts, and the insulation resistance of the generator stator grounding is 0 or minimum.

When insulation breakdown occurs in generator, the fundamental problem lies in weak insulation of stator coil or corona corrosion of notch in operation. The treatment methods are to find out the breakdown point, re-manufacture and reinforce the insulation, and at the same time, eliminate corona corrosion to the greatest extent.

Generator noise or vibration is large

Generator noise or vibration has the following situations:

(1) the anchor bolts are loose, or the unit sinks. Treatment: tighten bolts. Recalibrate concentricity.

(2) The generator rotor and the steam turbine shaft are not concentric. Handling: correcting concentricity

(3) The bearing wall is worn or damaged due to lack of oil. Treatment: repair bearings or replace new bearings of the same type.

(4) Friction between rotor and stator. Treatment: find out the place and reason of friction and eliminate it.

(5) Loose fan or other fasteners. Treatment: tighten the fan and fasteners.

(6) Local short circuit, two-point grounding or wrong wiring of rotor coil. Treatment: check the insulation of slip ring and rotor coil to the ground, or check the voltage drop, winding direction and wiring method of each coil with DC current, find out the cause of the fault and eliminate it.

(7) The brush is too hard or the pressure is too high. Treatment: adjust pressure or replace brushes of the same type.

(8) Three-phase current is seriously asymmetrical. Treatment: find out whether the unbalance degree of the three-phase current is within the allowable range, otherwise, adjust the three-phase load or appropriately reduce the load.

(9) Short circuit or grounding of stator winding. Treatment: find out the fault and repair it.

(10) External fault or lightning strike. Treatment: if the vibration time is too long, stop the machine for inspection

Generator temperature is too high

When the generator is in normal operation, when the current, voltage, frequency, power, excitation current and power factor change within the allowable range, generally speaking, the temperature of the generator is also within the allowable value. If the following conditions occur, the temperature of the stator, iron core and other parts of the generator will be too high.

(1) the overload operation of the generator exceeds the allowable time. Treatment method: reduce the load of generator to rated load or below as soon as possible

(2) Three-phase current is seriously unbalanced. Treatment method: find out the cause of unbalanced three-phase current; if it is the generator voltage, find out whether the generator is short-circuited between turns; if it is the load, adjust the load to make it as balanced as possible.

(3) The ventilation and cooling system of the generator is not good. For example, the air temperature is too high, the ventilation duct or exhaust duct is blocked, and there is serious dust accumulation between coils and their ends. Treatment method: reduce the load operation properly, improve the ventilation conditions, and remove the accumulated dust.

(4) Partial short circuit or grounding of stator winding. Treatment method: find the short circuit or grounding point and repair it, and eliminate the hidden danger of short circuit or grounding.

(5) The insulation of stator core may be partially damaged and short-circuited, resulting in eddy current and overheating. Treatment method: properly reduce the load operation. If the efficiency of the generator is significantly reduced, repair and repair the stator core of the generator as appropriate.

(6) Lack of bearing lubricating oil or wrong oil number, deterioration of oil quality, improper bearing installation and serious bearing damage, etc. Treatment method: find out the causes in detail, and change oil, clean, adjust or replace new bearings respectively.

Grounding of generator rotor

Fault phenomenon: the light plate of one-point grounding or two-point grounding of the generator is on

Fault analysis: the insulation damage of the generator rotor winding, serious coil deformation, serious dust deposition and greasy adhesion at the end, etc., will cause the generator rotor winding to be grounded. When the rotor winding of the generator is grounded at one point, there is no current passing through the grounding point because the electrical circuit to the ground has not yet been formed. However, after one point grounding, it is very easy to cause another point grounding, or when any part of the excitation circuit is grounded, two or more ground faults can be formed, which is very dangerous.

After the fault occurs, the rotor winding is short-circuited. Because the DC resistance of its winding is extremely small, the excitation current is bound to increase, the magnetic field of the generator is out of balance, and the main magnetic flux is greatly reduced, resulting in strong vibration of the unit. At the same time, the power factor of the generator is significantly increased, and it can run in advanced phase (absorbing reactive power of the power grid), changing the stator magnetic field before and the rotor magnetic field behind, which increases the stator current (current operation attendant, if it is found that the excitation is unchanged, the excitation current and stator current suddenly increase, the excitation voltage and AC voltage suddenly drop, and the power factor meter indicates that the generator rotor is grounded or may be inter-turn short circuit fault, so it should be stopped immediately.

Excitation Modification and Generator Test

The excitation system is reformed and upgraded, and the excitation of brushless exciter is changed to static thyristor excitation, which is convenient to maintain and use and eliminates the shortcoming of slow dynamic adjustment of brushless excitation; Generator test, including stator insulation resistance test, absorption ratio test, iron loss test, leakage test, AC/DC withstand voltage test, rotor high-speed dynamic balance and overspeed test, dynamic and static AC impedance test, generator no-load test, short circuit test, temperature rise test, residual voltage measurement and shaft voltage measurement.

We always insist on quality first to ensure the provision of continuous and stable high quality Solar Energy Photovoltaic Energy Solar Panel Power Generation Contractor and services. The company always adheres to the tenet of serving users and pursuing excellence, never forgetting its original intention, and forging ahead. We practice the refined management concept that has accumulated for many years, and gradually move from a manufacturing enterprise to a service provider.