Guangdong Electric Power Stator Cooling Water Interrupted Damage to the Generator and Repaired Wang Bin. Xinwenda Shayu Power Plant No. 52390, Dongguan, Guangdong, the main reason for the excessive vibration is that the end fixing method is weak and cannot withstand the thermal expansion caused by the constant temperature rise. After the accident, the manufacturer decided to temporarily improve the end of the generator windings. The capacity of the generator is constantly increasing, and the volume of the generator is not increased. This makes the heat capacity of the generator more fully utilized by the generator, and the remaining heat capacity becomes smaller, which cools the generator. The system puts forward strict requirements. If the generator cooling system appears frequently, it will easily cause the hair dryer to overheat. In Shajiao, the No. 3 generator of the power plant suffered an accident of cold water interruption in the stator of the generator on March 24, 1999, causing the generator to be damaged by the sound. The following describes the damage and repair caused by the generator after the accident, so that the peers can learn from it. Shajiao, the power plant has installed 3 sets of 660, generators of water-hydrogen-hydrogen cooling method produced by 00 D.0. Since its commissioning in 1996, three generators have suffered major failures. The main reason for the failure of No. 2 generator No. 3 is that the stator winding end of the generator is weakly fixed, and the fixed support arrangement of the lead wire is unreasonable, causing the lead wire to vibrate excessively. Big this. The manufacturer installed a line vibration monitoring device on the end of the ancestors and the outlets of the three sets of hairpins. The Kunming situation that occurred after the interruption of the cold water in the stator of the No. 3 generator was judged by the vibration monitoring result to judge the recovery of the mountain. After the generator of No. 3 on March 24, 1999, the generator was taken with the power of the generator. In the operation of the cold water sample, the error occurred, causing the internal cooling water to be removed from the skip pump and the starter to start the water machine. The original design of the generator water cut protection action is that the accident button of the 12 stator cooling water pump motor is pressed. The thermocouples of the two stator cooling water pump motors are all operating, the water level of the stator cooling water tank is low and the delay time is 5 when any of the above three conditions is satisfied. The water cut protection will act because the operating personnel at the time are taken on the connecting pipe of the water level gauge. In the water sample, the valve is opened too much during sampling, causing the water level of the water level gauge to fluctuate greatly, and the water level is low and the signal protection action. The cooling water pump that caused the operation of the household jumped, the water level fluctuated because the water signal of the original water tank could not be reset, and the water level low signal blocked the interlocking start of the standby pump, so the water cut protection did not work. The generator is operated under high load to transport the generator only to disengage the generator. Untie 3, also after. Restoring the cooling water in the recorder This generator does not have a sudden cooling after overheating. After the shutdown, it is seen from the trend of the outlet temperature of the stator bar that the temperature rises from the normal 55 to the highest 95 stator windings. The temperature of the cooling water rises from 5 to the highest 92, and the end core temperature is 59. Raised to the highest 72. Since there is no temperature measurement point between the upper line of the generator bar and the upper line bar of Shajiao Power Plant, only the temperature measurement point is installed on the outlet hose of each line cooling water, so the cooling water in the generator is interrupted 6 The seven methods accurately determine that the temperature rise on the stator bar is less. After the external inspection of the hairpin machine is normal, the old machine is restarted. After the unit is fully loaded, the temperature of the generator stator bar and the temperature of each part of the generator are normal. On March 28th, it was found that the amplitude of the 20th point of the vibration measuring point at the end of the stator winding of the turbine reached the alarm value alarm value, the sub-150, which is installed at the position of the end of the stator winding end 105 of the turbine side. The radial report of the winding, and the inspection found that the vibration at the 21st point of the angle of the same side position 285 is the same as that of the 20th point after the generator water break accident, and the large trend is the vibration of the 20th point and the 21st point. Amplitude Trend The amplitude of the vibration of Dongying Mountain is increased with the increase of the active power and reactive power of the generator, so the possibility that the vibration-detecting parts will fail due to overheating of the plant is excluded. Soliciting the intention of the manufacturer, it is believed that there is indeed vibration of the end winding, and the person is related to the water disconnection of the hair dryer. However, the vibration amplitude of the generator does not constitute a hazard. It is recommended that the vibration of the 20th point be reported from 5, respectively. 〃, 1 to 40, the vibration value of the 21st point is increased from 1001〃 to 400, the generator can continue to be transported, but after the alarm value is increased, to 418, the vibration of the 20th point reaches the new alarm value, the highest time. It has reached 457. Subsequently, in order to control the vibration below the alarm value, it is decided to operate the unit with a load limit of 300%, and then a detailed inspection will be carried out when the unit is scheduled to be minorly repaired on May 10. 2 Generator damage and analysis 2.1 Damage On May 21, the No. 3 generator was pulled out for inspection. More black muddy streaks were found on the side end of the stator side exciter. It mainly occurs on the spacer between the elastic plate and the end support frame, and several places on the end lead. After analysis, it is believed that the sludge is formed by the vibration of the powdered oil and gas mixture at high temperature. The windings were not found to have significant signs of insulation defects. 2.2 Failure Cause Analysis The vibration of the end winding of the generator turbine side is caused by overheating of the stator winding after the generator is shut off in the flood season. However, the generator has a large temperature rise in the winding 416 at full load. Because there is no temperature measurement point embedded in the winding, there is no direct measurement data, but it is calculated according to the parameters provided by the manufacturer. At this time, the high temperature does not exceed 150. The calculation process is slightly because the stator insulation of the generator is of the stage, so it is considered that this temperature has no influence on the insulation of the stator winding. However, because the temperature of the wire rod rises rapidly and is thermally expanded, and because the pad between the end bars of the winding machine is made of felt through the ring, the resin is used to stick the pad and the wire rod, and the unused tie band will The pad is bundled with the winding wire rod, so when the two bars are different in thermal expansion, a crack misalignment occurs between the bar and the pad, which weakens the generation and determines the effect. The vibration during operation is gradually increased, and the stator bar is cold water; 6 is drowning from the turbine side, and the water side is from the exciter side, so after the +1 hair dryer is cut off. The temperature rise of the wind turbine side end winding is more frightening than that of the exciter side, which leads to the serious situation of the looseness of the steam turbine side block. The way of remembering the end of the wide pouring is mainly to press the windings of the end to the support bracket of the outer ring of the winding by 3 inner hoops, and 12 support brackets are arranged in the outer ring of the winding, and the support frame passes through The bolt is fixed to the compression ring of the end core. The end windings of the same layer are adjacent to the line bar and the upper and lower line bars are fixed by the spacers and then injected with resin. That is to say, the fixing of the end bar is completely dependent on the outer ring branch, the pressing force is generated between the component and the inner hoop ring, and the pressing force generated after the crotch block is driven between the adjacent bar bars, the bar is fixed. There is no mutual lashing between them, and the overall end is poorly integrated. Therefore, we believe that the winding end fixing method is weaker than that of the same type of unit, and cannot withstand the reinforcement of the stator winding in the case of a person who has a vibrating person. The temporary reinforcement measures are that a pair of elastic ring and the outer ring support ring between the support bracket and the pad between the upper and lower windings of the pad between the winding bars are filled with resin, and the looseness gap which may be generated is fully filled by the fluidity. Remove the two inner retaining rings for fixing the end of the generator and fasten the six supporting press plates 3, and use the small press plate fixing method. There are 4 small pressure plates at the ends of two adjacent bars on each side, and each piece is divided into upper two halves. First, the heat-shrinkable belt is used to tie the two adjacent small pressure plates to the control ring outside the winding, and then the heat-shrinkable belt is tightened by heating, and then the pressure plate is pulled apart by a special force. The penetration is made to make the heat shrinkable band reach the required force. Finally, the resin curing manufacturer said that this treatment method was used on a 200 generator. 4 After the generator's master's operation hall, the generator is re-connected with load after being processed. The vibration situation was significantly improved. The value of the 20th point was reduced from the highest 457 yang 1 before treatment to 20 yang 1 and the value at the 21st point was reduced from the highest 2801 to about 35,1. Whether this improvement can really improve the vibration of the end of the generator winding, it also requires time to verify. As far as the current situation is concerned, this minor repair has improved the fixed condition of the end of the generator winding, so that the vibration amplitude of the end is within the safe range, but whether the strength meets the requirements still takes time to test. In this case. The generator winding end and the wire vibration on-line monitoring device played a big role, so that we found the defects of the generator end fixing early in the operation, and adopted the load-limiting measures to avoid the expansion of the fault and even the vibration. If it is too large, it will burn out. 3 The repair of the generator is engaged in the technical management of the operation of electrical equipment. After the accident, the manufacturer decided to carry out the end of the generator winding.
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Stator cooling water interruption damage to the generator and repair