基于改进声学有限元法的主变压器室噪声场计算

Calculation of Noise Field in Main Transformer Room Based on Improved Acoustic FEM

传统声学有限元法(finite element method,FEM)难以准确表征温升效应引起的主变室大空间空气介质参数变化,导致温度场-声场耦合作用下变电站主变压器室噪声场计算误差过大。在声学FEM算法基础上,引入计算流体力学(computational fluid dynamics,CFD),提取大空间主变室的复杂空间介质参量,并对波动积分方程进行改进,提出一种基于改进声学FEM的主变室内噪声场求解算法。首先,建立温度场影响下的主变室流变模型,采用CFD表征主变室大空间温度场离散空间介质参量;然后,基于流-声网格映射理论,将温度场离散空间介质参量与声音网格进行映射,建立修正大空间空气介质参数后的声学FEM积分方程;最后,基于常规Gauss数值积分法和引入Kirchhoff-Helmholtz方程,对修正声学FEM积分方程进行联合求解。该算法在西安110 kV昌明变电站1号主变室噪声场的求解分析中得到了成功应用,与实测值误差为2.168%。

The traditional acoustic finite element method(FEM)is difficult to accurately characterize the change of air medium parameters in the large space of the main transformer room caused by the temperature rise effect,resulting in the large calculation error of the noise field in the main transformer room of the substation under the coupling effect of temperature field and sound field.Based on the acoustic FEM algorithm,computational fluid dynamics(CFD)is innovatively introduced to extract the complex spatial medium parameters of the large space main transformer room,and the wave integral equation is improved,and a noise field solution algorithm in the main transformer room based on the improved acoustic FEM is proposed.Firstly,the rheological model of the main transformer chamber under the influence of temperature field is established,and the discrete space medium parameters of the large space temperature field of the main transformer chamber are characterized by CFD;Then,based on the fluid-acoustic grid mapping theory,the discrete space medium parameters of the temperature field are mapped to the acoustic grid,and the acoustic FEM integral equation is established after correcting the air medium parameters in large space;Finally,based on the conventional Gauss numerical integration method and the introduction of Kirchhoff-Helmholtz equation,the modified acoustic FEM integral equation is jointly solved.The algorithm has been successfully applied to the solution and analysis of the noise field in the No.1 main transformer room of Xi’an 110 kV Changming Substation,with an error of 2.168%from the measured value.