Experimental Study on End Heating of QFSN-650-2 Turbine Generator

Wang Haibo Harbin Electric Power Vocational and Technical College Han Xiaohui Heilongjiang Electric Power Worker University Han Jingsheng Harbin Institute of Electrical Machinery and Wensheng's distribution law. The rationality and reliability of the stator end structure design of the generator are established. : Turbine Generator End Heat Test 1 Introduction With the increase of the single-machine capacity of the steam turbine generator, the electromagnetic load of the motor has exceeded 2000A/cm. The leakage magnetic field at the end of the motor has increased significantly, and the iron core and structural parts at the stator end of the motor. It causes a large loss of heat, which may cause overheating of the relevant parts at the end of the motor and affect the safe operation of the motor.

The QPSN-650-2 turbo generator is the first nuclear power product of Harbin Electric Co., Ltd. The stator line load of this machine is! =2118A/cm, the maximum air gap magnetic density 褚=l.16T. In order to improve the stator end heat generation, reduce the end loss, and avoid the local concentration of the end magnetic field and loss, the following measures were taken in the design: non-magnetic cast steel Pressure finger and non-magnetic cast steel block small pressure plate to reduce the loss on the pressure finger and pressure plate.

The iron core section of the stator edge is provided with a small step, and a small groove of 3 mm wide is opened in the edge of the core core to limit the eddy current caused by axial leakage.

Both ends of the stator core are provided with a stepped magnetic shield stack to split the magnetic field at the end, reducing end leakage and reducing end loss.

Considering the overall design, the effective core length of the stator (6300mm) is 50mm longer than the effective length of the rotor core (6250mm). This can reduce the end synthetic magnetic field to reduce the leakage of the end at the end of the motor load. Reduce end loss.

The stator winding of the generator is water-cooled, the rotor winding is hydrogen-cooled, and the stator core and the end structural member are hydrogen-cooled. The rotor of the motor is symmetrically equipped with a rotary axial fan; the top of the motor is symmetrically equipped with a hydrogen cooler at the top, and the whole motor is a five-in and six-out air-gap radial multi-channel ventilation system. The rated hydrogen pressure of the motor is PH=.4MPa. Radial ventilation ducts are provided at the end of the stator core and the magnetic shield at the end to improve the cooling effect.

In order to check and verify the reliability and design rationality of the stator end structure of the motor. We tested the magnetic field and temperature rise of the stator end of the machine.

2 Test content and measurement method This test mainly measures the magnetic field and temperature of the stator end of the generator under no-load and short-circuit conditions to determine the distribution law of the magnetic field and temperature at the end of the generator, and to identify the end of the motor. Magnetic flux leakage and overheating.

Test conditions: The magnetic field at the end of the generator stator is measured at no-load conditions (t/hour).

The stator stator end temperature is measured at 1.05, 1.2i/N) and short-circuit conditions (/K=1/n, 1.46/N, 1.08/n).

The magnetic measuring component adopts a small coil for detecting; the temperature measuring component adopts a copper-constantan thermocouple.

In the stator end of the generator, the test components are divided into two groups, a total of 16 measuring points, a thermocouple and a small coil are buried in each measuring point, and 32 test elements are embedded. The measuring point positions are respectively distributed vertically above the horizontal end of the stator end of the motor and in a horizontal position. The buried position is seen separately.

At the same time, a resistance thermometer is embedded in the cold and hot air zones of the generator cooler, and a thermocouple is arranged on the measuring end of the test component. Measure cold, hot hydrogen and ambient temperature separately.

The test component leads are wound around the end of the tapered ring end through the outer end of the motor end winding neutral rod bar, and are fixed with epoxy adhesive and white cloth tape, and then taken out by the cooler manhole test cover sealing device.

The end magnetic density is measured by the small coil of the detection - FLUKE high-precision digital multimeter method.

The end temperature is measured by a copper-constantan thermocouple- 7K2731/2741 computer data acquisition system.

The cold hydrogen temperature and the hot hydrogen temperature were measured using a /WP thermal resistance computer data acquisition system.

The hot spot is measured without a freezing point, and the temperature at the terminal block is measured as a thermal couple cold spot compensation.

3 Results and Analysis 3.1 The alternating magnetic field at the end of the end field magnetic motor is an intrinsic factor that causes the end of the stator of the motor to heat up. It is produced jointly by the ends of the stator windings. The end magnetic field varies with the operating conditions of the motor, the material, size and position of the various components at the ends.

3.1.1 Magnetic density distribution of the stator end The test results of the magnetic end of the stator end under various working conditions are shown in Table 1. The maximum magnetic density of each working condition is shown in Table 2. The magnetic density of the end is compared under the two conditions of no-load and short-circuit. See Table 1 and Table 3. It can be seen that in the no-load condition, the core core magnetic density is much larger than that of the short-circuit nuclear power 650MW turbine generator stator end vertical point; while the short-circuit operation is magnetic shielding points and small The magnetic density of the pressure plate is very large. Under the two working conditions, the magnetic density difference of the pressure finger is small.

The distribution law of magnetic density at the end of the stator during no-load and short-circuit operation decreases with the increase of the distance between the air gap and the air gap between the stator and the rotor. That is, the magnetic core density of the core is the highest, the pressure is the second, and the magnetic shielding is the lowest. And consistent with the law of design calculation.

It can be seen from the measurement results of various working conditions that the magnetic density of the edge core and the pressure finger surface is mainly affected by the rotor current, and the influence of the stator current is relatively minor. The magnetic tightness of the magnetic shielding surface is opposite to that of the stator current, and the influence of the rotor current on it is secondary.

Table 1 QFSN50>2 type turbine generator stator end magnetic density measurement result position condition\tight side section core second section (tooth top) side section iron core section 1 (tooth top) pressure finger (top) pressure finger (bevel) Magnetic shield (inner edge) magnetic shield (outer middle) outer magnetic shield (inner edge) small pressure plate (outer side) empty one-phase steady-state short circuit one table 2 most magnetic and dense position measurement point position magnetic close Condition point position magnetic density no-load phase steady-state short-circuit table 3 no-load, short-circuit jingjing magnetic density comparison table position position \ dense 10-4 side core pressure finger magnetic shielding small pressure plate table 4QFSN> (iS0~2 type Turbine generator stator heel temperature measured value (hydrogen pressure 0.4MFIO no-load three-phase steady-state short-circuit cold hydrogen heat hydrogen environment 3.2 stator end temperature rise due to the end of the motor alternating magnetic field caused eddy current loss in the end structure The heat, under a given cooling condition, shows a certain temperature rise. The total loss of the end of the motor is generally small, usually the local loss density is high in some parts. If the cooling is not good, the end of the stator is often caused. The temperature rise is too high. The eddy current loss induced by the alternating magnetic field is the internal cause of the end heating. The effect of the upper cooling condition is comprehensively expressed as the end temperature rise, and the end temperature rise often limits the safe operation capability of the generator, which is valued by everyone.

The purpose of the end temperature rise test is to determine the temperature rise distribution at the end of the stator, to study the law of end heat generation with load and the cooling effect of the end structure.

3.2.1 Temperature rise of the stator end The measured results of the stator end temperature under various working conditions of the generator are shown in Table 4. Under different working conditions, the maximum temperature and temperature rise of the stator end structural members are shown in Table 5. Comparing the temperature rise of the end under load and short circuit conditions, see Table 4 and Table 6. The highest point is that the temperature rise of the core tip of the edge is 14.4K. The temperature rise of the stator end is not high during short circuit operation, short circuit 1.0/N Under the working condition, the highest point is the same as that at no-load, and the temperature rise at the top of the iron core of the edge is 8.4K. Moreover, the maximum temperature rise of the stator core is 14.4K, which is the highest temperature than the stator core. The highest temperature rise point during load and short circuit is not much different from other points. The maximum phase difference is 13.6K when no load is 0=1.05; the maximum difference is only 7.1K when short circuit/K=1.0/N. The end temperature rise is relatively uniform.

The temperature rise of the small pressure plate of the stator end block is not high, the highest temperature rises to 1.4K when no load (/=1.05f/N), and the maximum temperature rises to 5.5K when the short circuit (/K=1.0/N). See Table 6. The temperature rise of the load can not be obtained in the production plant. It is calculated by the no-load temperature rise and the short-circuit temperature rise. The calculated maximum temperature rise of the end load is still 11.6K at the tip of the stator core. See Table 7. Theoretically, if the magnetic circuit saturation and the heat exchange of each part of the motor are not counted, the load temperature rise has the following relationship with the corresponding short-circuit temperature rise and no-load temperature rise: load power factor angle.

3.2.2 Temperature rise of the stator end The distribution law of the temperature rise of the end of the motor during no-load and short-circuit operation is basically consistent with the law of magnetic field distribution. Both increase in temperature and decrease in temperature. That is, the core of the edge is the highest, the pressure is the second, and the temperature rise of the magnetic shield is the lowest.

Table S most ascending and position conditions no-load three-phase steady-state short-circuit measuring point position measuring point temperature (duplicate) cold hydrogen temperature (especially) hot hydrogen temperature (t) ambient temperature (t) measuring point temperature rise (K) 6 No-load, short-circuit, excitation, rise, comparison, side, section, core, pressure, magnetic shield, small pressure plate, \(K)\temperature condition, edge, core pressure, magnetic shield, small pressure plate, lift load, short circuit, K, 7 stator, Jing Department Negative planting calculation value (pressure 0.4MP8 4 conclusion measurement results and analysis can draw the following conclusion: the closer the stator end of the generator is to the air gap, the stronger the magnetic field. The most magnetically dense point is in the side when no-load and short-circuit operation On the segment core, the magnetic density on the core of the segment is much larger than that at the time of no-load; the magnetic density at each point on the magnetic shield is much higher than that at no-load.

When the generator is running at no load (t/o=1.05f/N), the maximum temperature of the stator end rises to 14.4K; when the (/K=1.0/N) short-circuit operation, the maximum temperature of the stator end rises to 8.4K. Both are lower than the design calculation (27.8K).

The distribution law of the temperature rise of the stator at the time of no-load and short-circuit operation is basically the same. That is, the core of the edge is the highest, the pressure is the second, and the temperature rise of the magnetic shield is the lowest. The highest point of temperature rise is at the top of the iron core of the edge section, and the highest temperature rise point at no load and short circuit is not much different from the temperature rise of other points.

The magnetic density of the iron core and the pressure finger of the stator is high under no-load and short-circuit conditions. The magnetic density of the magnetic shielding points is also large when the short-circuit is running; but the temperature rise of the whole end is not high (up to 14.4K) ). It can be seen that for the stator end (iron core and structural parts), the air gap and the end air inlet amount under 0.4 MPa hydrogen pressure are sufficient, and the distribution is uniform, and the cooling effect is good.

The experimental result shows that the maximum temperature rise point (edge ​​core) of the stator end of the generator is 14.4K. If the cooling hydrogen temperature is as high as 46:, the maximum temperature of the core is 60.4, which is far lower than the B-class insulation temperature limit. Value (130). The stator core and structural parts of the stator are free from overheating.

Therefore, through the test, it can be considered that the stator end structure of the QFSN-650-2 turbo generator produced by Harbin Electric Company is reasonable in design and reliable in operation. The stator core and structural parts of the generator have met the design standard requirements.

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