基于鲸鱼算法的风机接地网优化设计

Optimized Design of Wind Turbine Grounding Grid Based on Whale Algorithm

接地系统是风电机组防雷设计保护的重要部分,接地网的几何形状关乎雷击冲击特性。传统等间距接地网遭受雷击后产生巨大的接触电压,严重危害机组的正常运转,而利用优化算法求解最优压缩比构建不等间距接地网能有效降低接触电压。文中提出基于混沌动态权重因子和非线性收敛因子的优化鲸鱼算法(FWOA),求取最优压缩比,解决传统粒子群算法(PSO)早熟和寻优精度低等缺陷,在ATP-EMTP中搭建集桨叶、塔筒、电缆、接地网为一体的风机全局波阻抗模型,考虑火花效应和增设垂直导体对暂态电位的影响的基础上,探讨矩形接地网在风机防雷的应用,与圆形接地网作对比验证FWOA的优越性。仿真结果:文中提出的FWOA精度更高、收敛速度更快,降低接地网接触电压高达30.43%,与圆形接地网暂态情况相差无几,若所受环境或经济成本有限制,则可考虑不等间距矩形接地网;冲击电流产生的火花效应能降低接地网的冲击电阻;增加垂直接地导体能加快散流,改善风机接地网运行的安全问题。

The grounding system is an important part of the lightning protection design and protection of wind turbines.The geometry of the grounding grid is related to the lightning strike characteristics.Traditional equal-spaced grounding grid produces huge contact voltage after being subjected to the lightning strike,which seriously endangers normal operation of the unit.However,the use of optimization algorithm to solve the optimal compression ratio to construct unequal-spaced grounding grids can effectively reduce contact voltage.In this paper,an optimized whale algorithm(FWOA)based on chaotic dynamic weighting and nonlinear convergence factors is proposed to obtain the optimal compression ratio and to solve such shortcomings as premature and low optimization accuracy of traditional particle swarm optimization(PSO).The global surge impedance model of wind turbines integrating blades,towers,cables,and grounding grids is set up in ATP-EMTP and,on the basis of considering the spark effect and the influence of additional vertical conductors on the transient potential,the application of rectangular grounding grid in wind turbine lightning protection is discussed.The circular grounding grid is compared to verify the superiority of FWOA.The simulation results show that the FWOA proposed in this paper has higher accuracy and faster convergence speed,and reduces the contact voltage of the grounding grid up to 30.43%,which is comparable to the transient situation of the circular grounding grid.If the environment or economic cost is limited,the unequal spacing rectangular grounding grid can be considered.The spark effect produced by the impulse current shall be able to reduce the impulse resistance of the grounding grid.Addition of a vertical grounding conductor can accelerate the dispersion of current and improve the safety of operation of the wind turbine grounding grid.