Noise and Vibration Prediction in Shunt- Reactor using Fluid Structure Interaction Technique by PARMATMA DUBEY CROMPTON GREAVES LTD. parmatma.dubey@cgglobal.com and VIJENDRA GUPTA CROMPTON GREAVES LTD. vijendra.gupta@cgglobal.com
Contents: Shunt reactor Introduction Noise and Vibration Prediction Methodology Test Cases Shunt reactor Modelling Modal and Harmonic Response Vibration Prediction Noise Prediction Conclusion 2
Shunt-Reactor : Introduction core LAMINATION Shunt reactor which appears similar as a power transformer, is commonly used for reactive power compensation in long high-voltage transmission lines. 3
Shunt-Reactor : Noise and Vibration Prediction Methodology Input: Mass, Stiffness FEM TOOL Output: Natural frequency, Mode shape Input to Force Response Harmonic and Acoustic Analysis 4
Vibration Transmission: Alternating Electromagnetic Flux Core vibration due to magnetostriction Core vibration due to transverse magnetic forces Core Vibration Vibration transmission through fluid (oil) Vibration transmission through structural mounts Tank Vibration 5
Test Case- Natural Frequency Validation Fabricated tank with accelerometers Tested mode shape in LMS Test lab. Tested frequency, 438 Hz Simulated mode shape in ANSYS Simulated frequency, 443 Hz Note: The difference between tested and simulated value of natural frequency is less for shell element (within 5%) in comparison to solid element (within 0%). 6
Effect of Fluid on Dynamic Characteristics of Tank Table: Natural frequency comparison using experiments Mode No Fluid Filled tank Empty Tank 52 229 2 242 344 3 260 357 4 308 47 5 44 434 6 457 459 7 475 487 Fluid is changing the dynamic characteristics of the tank. Hence it is necessary to model the fluid for reactor vibration prediction. 7
Shunt Reactor: Model Detail TANK FLUID CORE Boundary Condition: Base pads are fixed Core inside fluid Major Steps in FEA Create meshed model with specified elements Compensate the missing mass with density adjustment Total mass of the structure : 05 Tons Assign fluid density and speed of sound in fluid to the fluid elements Define Fluid-Structure Interface at the common surface. 8
Shunt Reactor: Model Detail Major Material Components: Core: Grain oriented steel Winding: Copper Tank: Mild steel Support between core and tank: Compressed wood Fluid: Mineral Oil CORE Fluid Element Properties: Fluid Density: 870 kg/m 3 Speed of sound in fluid: 400 m/s Finite Element Selection: Core and Winding: Solid tetrahedral 0 node 87 Tank: Shell 8 node 28 Compressed wood: Solid tetrahedral 0 node 87 Fluid: 3D acoustic 0 node tetrahedral 22 9
Shunt Reactor: Forces on Core Magnetostriction Force Transverse magnetic Force 0
Shunt Reactor: Normal Modes near 00 Hz Normal modes near 00Hz frequency have been extracted because of the presence of forcing frequency at 00Hz High voltage side Neutral bushing side SET TIME/FREQ 95.559 2 97.995 3 99.227 4 0.22 5 02.49 6 04.5 Normal modes near 00Hz
Harmonic Analysis- Vibration Prediction Rear Part Response at 00Hz Imaginary Part Tested overall vibration: approx. 50 µm 2
Noise Prediction Sound Pressure Level on HV side: 78dB Sound Pressure Level on neutral side: 75.7dB 3
Noise Prediction Maximum Noise Level on 4 sides: High voltage side: 78dB Neutral side: 75.7dB Shorter side : 80.9dB Shorter side 2: 80.9dB Sound Pressure Level on shorter side: 80.9dB Overall tested noise: 79dB 4
Conclusion: Effect of fluid on normal modes of a structure has been presented Sloshing effect has been neglected as the tank is fully filled with oil Presence of fluid significantly changes the natural frequencies of the structure Change in natural frequency is more significant towards lower normal modes Simulated natural frequency in ANSYS has been validated with tested natural frequency and mode shape This methodology has been used to predict reactor vibration and sound pressure level. 5
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