The damage caused by the interruption of the generator cooling water from Guangdong Electric Power and the repair of Wang Bin . Sinwenda Shajing Power Plant, Dongguan 52390, Guangdong, the main cause of 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 tighten the generator windings to improve the situation.
The capacity of the generator is constantly increasing, and the volume of the generator is not increased, which makes the thermal capacity of the generator more fully utilized by the generator. The remaining heat capacity of the generator becomes smaller, which cools the generator. The system puts forward the strict request, if the generator cooling system appears frequently, it is easy to cause the machine to overheat. In Shajiao, power plant No. 3 generator suffered an interruption of cold water in the stator of the generator on March 24, 1999, which caused the generator to be damaged. The following describes the damage and repairs caused by the generator after the accident, so that peers can learn from it.
In Shajiao, the power plant has installed a total of three sets of 660, generators produced by 00 0 0 æ°´ of water and hydrogen hydrogen cooling. Since it was put into operation in 1996, three generators have all experienced major failures. The main reason for the fault of No. 2 No. 3 generator is that the stator stator winding ends are weakly fixed, and the fixed support arrangement of the lead wires is unreasonable, causing the vibration of the lead wires to be excessive. This is big. The manufacturers installed line vibration monitoring devices at the end of each of the 3 sets of transmission machines and the 1 outlets. After the interruption of the cold water in the stator of the No. 3 generator, the Kunming situation was judged by the results of the vibration monitoring to determine the arrival of the mountain. After March 24, 1999, No. 3 generator took generator power in the generator stator. Failure of the cold water sample during the operation, causing the inner cooling water to be dry from the jump pump to start over and start the machine. Water shut down accident The original design of the water cut protection action is based on the condition that the 12 stator water pump motor accident button is pressed. The thermocouples of the two stator cooling water pump motors are all active, and the stator cooling water level is low and delays 5 When any one of the above three conditions meets one, the water cut protection will act because the operator at that time is on the connecting pipe of the water level gauge. In the water sample, the valve was opened too large during the sampling, causing the water level of the water level meter to fluctuate greatly and the water level signal protection action. The cooling water pump that caused the shipment to move will jump, and the water level will fluctuate because the water level signal of the original tank cannot be reset, and the low water level signal blocks the chain start of the standby pump, so that the water cut protection does not act. The generator is operated under high load so that only the generator can be disengaged and the generator decoupled. Solution 3, also later. Recovering the cooling water in the generator This generator does not have the condition of sudden cooling after overheating. From the trend of the outlet temperature of the stator bar after shutdown, it can be seen that the temperature rises from the normal 55 to the highest 95-degree stator winding leads to the cooling water temperature in the line, rising from 5 to the highest 92, and the core temperature at the tip is from 59, Increased to the highest 72.
Because there is no temperature measurement point between the upper bar and the upper bar of the generator bar at Shajiao Power Plant, a temperature measuring point is only installed on the outlet hose of each bar cooling water, so the cooling water in the generator is interrupted. Seven methods accurately determine the temperature rise on the stator bar. After normal inspection of the dispatching machine, the old machine was restarted. After the unit was fully loaded, check the temperature of the generator stator bar and the temperature of each part of the generator.
On March 28, it was found that the amplitude of the 20th point of the vibration side of the stator side of the turbine side reached the alarm value of the alarm value, sub-150, which was the position of the angle 105 of the stator winding end 105 installed on the turbine side. In the radial direction of the winding, the inspection found that the vibration of the 21st point installed at the 285-angle of the same side position began to gradually increase with the 20th point after the generator water-cutting accident. The vibration of the 20th point and the 21st point was a big trend. Amplitude Trend The amplitude of vibration in Dongyingshan Mountain is increased with the increase of the generator's active power and reactive power, so the possibility of measuring the vibration of children by the plant overheating may be eliminated. The intention of the factory was sought and it was believed that there was vibration of the end windings, and that people were involved in water shutoff, but this vibration amplitude would not pose a hazard to the normal operation of the generator. It is recommended that the 20th vibration be reported to be 5 respectively. 〃 , , , 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 418 418 418 418 418 418 418 418 418 418 1 1 1 1 1 1. Once reached 457, then, in order to control the vibration below the alarm value, determine the unit load limit 300 PCT operation, such as the May 10th unit plan minor repairs and then do a detailed inspection.
2 DAMAGE AND ANALYSIS OF THE GENERATOR 2.1 Damages On May 21, the No. 3 generator was checked for its rotor. A lot of black muddy streaks were found on the side of the exciter side of the stator turbine side. Mainly occurs between the elastic bar and the end of the bracket between the line bar pad, there are several on the end of the lead. After the analysis, it was thought that the oil sludge was produced by the vibration of the powder gas-oil mixture at high temperature. No traces of insulation defects were found on the windings.
2.2 Causes of fault analysis The vibration of the side windings of the generator turbine is mainly caused by the overheating of the stator windings after the generator has been cut off. However, the generator runs at full load and water cut 416. The temperature rise of the set-up windings is more than that. Since there are no temperature measurement points on the windings, there is no direct measurement data, and calculations are based on the parameters provided by the manufacturer. At this time, the high temperature does not exceed 150 counts slightly because the stator insulation of the generator is graded, so this temperature is considered to have no effect on the insulation of the stator windings. However, because the temperature of the wire rod rapidly rises and expands due to heat, at the same time, since the Spacer between the wire rods at the end of the winding machine is felted with a felt to pierce the ring, the resin and the wire rod are adhered to the wire rod, and the tape is not used. The pad is bundled with the winding wire rods, so when the two wire rods are under different thermal expansion conditions, cracks will be generated between the wire rods and the pad, and the generation will be weakened and fixed. The vibration caused by the operation gradually becomes large, the stator bar cold water; 6 from the turbine side of the water, from the side of the exciter side of the water, so +1 turn after the water machine. The temperature rise of the turbine-side end winding is more frightening than that on the exciter side, resulting in a more serious situation where the turbine side cushion loosens. The way to remember the end of the casting bowl mainly depends on three inner support hoops to press the windings of the end to the support bracket of the outer ring of the winding. 2. There are a total of 12 support brackets arranged on the outer ring of the winding. The bolt is fixed to the compression ring of the end iron core. The end windings are fixed between the adjacent struts and the upper and lower struts by the spacers and then the resin. In other words, the fixing of the end bar is completely fixed by the pressing force generated between the outer ring support, the component and the inner support hoop ring and the pressing force generated after the ram block is inserted between the adjacent bars. There is no mutual banding and the overall integrity of the entire end is poor. Therefore, we believe that this way of fixing the end of the winding is weak compared with the same type of unit and cannot withstand the reinforcement of the stator winding when the cause of the stator vibration is excessive. Temporary reinforcement measures are to infuse the resin between the upper ring and the upper and lower coils between the elastic ring and the support bracket, and between the upper and lower layers of the interwinding pad, and the loosening gap that may be generated is filled with the fluidity.
Remove the two ends of the generator fixed with two internal support rings and the buckle should be six support pressure plate 3, use a small pressure plate fixation. There are 4 small platens at the ends of two adjacent bars on each side, each divided into two halves. First called the heat shrinkable belt will be adjacent to the two small pressure plate and the control loop outside the winding tightly bound, the heat to tighten the heat shrink zone, then 6 and then dedicated workers to pull open the pressure plate. Into the oblique so that the heat shrink tape to meet the requirements. The final coating resin curing manufacturer said this treatment method was used on 200 generators.
4 The condition of the dwelling room after the father and the father of the generator After the generator was processed, it was reconnected with the load. The vibration situation improved significantly. The 20th point value decreased from the highest 457 positive 1 before processing to 20 positive 1 and the 21st point decreased from the highest 2801 to about 35,1. Whether this improvement can really improve the vibration at the end of the generator winding will also need time to verify. As far as the current situation is concerned, this minor repair has improved the fixed state of the winding end of the generator so that the vibration amplitude of the end is in a safe range, but it is still time-tested if the strength meets the requirements.
In this incident. The on-line monitoring device of generator winding end and lead vibration has played a great role, so that we found the defects of the fixed end of the generator as soon as possible during operation, and adopted measures to limit the load, to avoid the expansion of the fault, and even to cause vibration. Too large and short circuit burned.
3 The repair of the generator was engaged in the technical management of the operation of the electrical equipment. After the accident, the manufacturer decided to proceed to the end of the generator winding.
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