Calculation of unbalanced electromagnetic force of a hydroelectric generating unit

The calculation of the unbalanced electromagnetic force of a hydro-generator unit in the journal of Tangshan College, Chen Liqing, Tang Shanshang, etc., the basic department of the Tangshan 063000, Hebei Province, Tangshan 063000, the unbalanced electromagnetic enthalpy and electromagnetic degree were calculated and solved. Actual question on the project.

Medium, class number. 39 unbalanced electromagnetic force, also known as unilateral electromagnetic force, the result of electromagnetic action of the public generator set. It can greatly reduce the natural frequency of the shafting system, aggravate the vibration of the shafting system and affect the power generation quality. Since the rotor is inevitably eccentric, the unbalanced electromagnetic force and the eccentricity are one side, so the balance electromagnetic force exacerbates the eccentricity. This will create a hazard to the history. Flash this, the heart must be fully in-depth analysis and calculation of the + balance 屯 magnetic escape to achieve control and reduce its purpose.

The characteristic of the transfer of the hydro-generator is that all of its magnetic poles are barely hung on the yoke, which brings certain difficulties to the calculation of the rotor magnetic potential and other related calculations. In this paper, the rotor and stator of the Qianxi hydro-generator unit in Hunan Province are calculated, and the mathematical equation of the stator magnetomotive rotor potential and the generator air-gap magnetic field energy under the grid-connected symmetrical steady-state operating conditions are obtained. The eccentric displacement is used to obtain the partial conductance, and the unbalanced electromagnetic force and electromagnetic rigidity are obtained. In order to obtain the energy of the air gap magnetic field, the magnetic potential and air gap permeability of the stator rotor must first be obtained. The solution is solved in turn below.

1 stator rotor magnetic potential and air gap magnetic permeability calculation 乜 迅 迅 迅 迅 水 水 水 水 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅 迅The phase sequence distribution is completely symmetrical, and the number of stator slots is 720. 1 Since the number of phases is 3, the rotor of the generator has 88 poles, so the number of slots per phase per pole is 24. The number of slots per phase per phase is not a fractional winding. The advantage of the fractional slot winding is that the hydroelectric generator set with low capacity and low speed is used to reduce the utilization of the effective material of the ferritic iron in the middle of the slot insulation, reduce the volumetric weight and manufacturing cost of the motor, and weaken the harmonic magnetic density. The induced harmonic potential causes the potential waveform to approach the claw shape.

1. Calculation of the magnetic potential of the stator single-phase winding Since the stator of the unit has 720 slots and the number of pole pairs of the rotor is 44, the greatest common divisor is 4. According to the literature 2, the entire stator slot can be divided into 4 units, each Units occupy 180 slots. Taking 180 slots as the dragon cycle, the Fourier series expansion of the stator single-phase winding magnetic potential is calculated. The stator magnetization is calculated. The final result of the phase winding synthesis magnetic potential is the stator current RMS.

13 rotor harmonic analysis of the rotor turned 88 magnetic poles evenly mounted in the magnetic enthalpy. In the analysis of the rotor magnetic potential harmonics, 1 the magnetic pole is spread in the circumferential direction, and the magnetic potential is every two magnetic cycles. In the cycle of Ke Ying 2 electrical angle, the calculated rotor magnetic potential is 71 for the excitation current = 17 is the number of turns of the field winding is the electrical angle.

The air-gap magnetic conduction method considers the air gap magnetic permeability when both the salient pole and the eccentricity are considered. The air gap magnetic field energy and the unbalanced electromagnetic force are calculated in the front. Both the rotor magnetic potential and the air gap magnetic permeability are static. The state is separately measured by the rotor to be small to rotate the rotor. The fundamental phase of the rotor should be advanced. The stator magnetism fundamental wave phase 729 + electrical angle, where 0 is the power angle, 1 power factor angle, so it should be 1 Escape the appropriate replacement with a stationary account as a reference system.

The rotor magnetic potential of the farmer's type 3 is called the ten Shi 7 jade as a substitute. Let 19+ be calculated to obtain the FjTCicos air gap magnetic permeability.

The calculation formula of the air gap magnetic field energy is 1 in the above formula, the day is the average radius of the rotor, and 1 is the effective length of the rotor is the pole logarithm. Delete some minor high-order small items, which can be calculated through complicated calculations. When the rated operating state is obtained, the relevant data can be substituted. After calculation, the heart can be obtained. The heart 6.7= is the rotor centroid in two mutual The amount of vibration displacement in the vertical direction.

Here, it is the generalized average air gap length. Since the air gap length between the rotor and the stator of the salient machine is uneven, when calculating with 9 , the generalized average of 6 must be obtained first. The calculation process is as follows.

It is known that the circumferential length of each magnetic pole on the outer circumference of the rotor is 0.4381. The circumferential length between the two magnetic poles is 0.154, and the maximum air gap length between each magnetic pole and the stator is 03, the minimum air gap length. It is 0.02, and its average is 0.0251. The length of the gap between the two magnetic poles is 0.34, but considering the space of the field winding, the actual air gap length can be taken as half of the designed air gap length of 0.171. . The unbalanced electromagnetic force can be calculated in the 1 〃 mode, especially in the 7 direction, = 6.272. is the generalized average air gap.

Using the above formula, when given the eccentricity of the vibration, after 7, the unbalanced electromagnetic force is easily solved. For example, the engineering stipulates that the vibration eccentricity is not allowed to exceed, the small air gap 1 says, that is, 2 is the theoretical ten-square calculation; =O.OO2rW, v.9O6336lrfN, s is equivalent to the eccentric mass of the additional ton, which should be fully considered.

The electromagnetic stiffness is defined as the coefficient of the electromagnetic force reaching the secondary term of the formula 10, which has the zetamagnetic stiffness and the support stiffness of the upper guide bearing. The support stiffness of the 1 and lower guide bearings is very close to 1.66. Because this electromagnetic constraint will have a greater impact on the dynamic coherence frequency of the shafting, the treatment can be known 4, which can reduce the dynamic natural frequency 35. 3 conclusions and recommendations 1. This paper gives a simple and easy solution A new method for the electromagnetic force of a hydroelectric generating set, the method can also obtain the electromagnetic rigidity.

The neodymium magnetic stiffness of the two-wheeled water turbine generator set will avoid the human color sound of the dynamic solid frequency production of the shafting system. After paying for the model machine, it can reduce the dynamic ancient frequency 3 pairs. 3. In order to reduce the unbalanced electromagnetic force, the vibration eccentricity and the appropriate air gap length can be minimized.

Wang Yihan and so on. Electromechanical design of Qianxi Hydropower Station. Hydropower, 1994, 5963.

White Yannian. Hydrogenerator design and calculation 1. Beijing Machinery Industry Press. 198 Niu Xiuyan. The motor is elbow. Beijing Metallurgical Industry Press, 1990.169195.

Chen Guiqing. Large-scale hydro-generator rotor shaft system is excited by bending and torsional nonlinear vibration of electromagnetic parameters. 0. Tianjin Tianjin University Editor Zhao Heming

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