The Research Of Pollution Deposition Characteristics Of UHV DC External Insulation And Self-cleaning Anti-pollution Technology

With the proposal of the “Air Pollution Prevention And Control Plan”,the “Three-year Action Plan for Blue Sky Protection” and the "dual carbon" goal,it is of great significance to optimize the energy distribution reasonably and transfer the green energy such as photovoltaic,wind and hydro energy from the western region to the eastern region to achieve large-scale trans-regional power energy transmission.UHVDC transmission lines are characterized by high effective transmission power,small line loss,small footprint and long transmission distance,which is the best method to realize large capacity and long distance power transmission.However,compared with UHVAC transmission lines,UHVDC lines are more dangerous in terms of pollution deposition and flashover due to their own particularity.Therefore,how to quickly,efficiently and accurately analyze the pollution state of the external insulation surface of UHVDC transmission lines and the corresponding pollution flashover voltage is of great significance to the prevention and control of pollution flashover accidents and ensure the safe and reliable operation of transmission lines.Using natural deposit pollution experiment platform,the pollution deposition and pollution flashover characteristics of insulator surface in strong DC electric field were investigated in this paper.A new method of self-cleaning on superhydrophobic coatings assisted by electric field was explored.It is of great theoretical significance and practical engineering value for the prevention and control of pollution problem on the external insulation.Aiming at the pollution problem on external insulation of UHVDC transmission lines,the particle radius of pollution,the distribution characteristics of pollution and the pollution flashover characteristics corresponding to the pollution characteristics are analyzed form the microscopic characteristics of pollution on external insulation surface in this paper.Firstly,a simulation test platform for natural deposition of pollution was built,and the distribution and particle radius characteristics of pollution on external insulation surface were revealed in DC electric field.It was found that the distribution of pollution on external insulation surface was in chain shape,and there was aggregation effect of pollution particles on the surface.Based on the theory of thermodynamics,electrostatics and hydrodynamics,a model of pollution aggregation in electric field was proposed,and the model was improved considering the hydrophobicity and charge characteristics on insulator surface.The influence of different pollution micromorphology on pollution flashover voltage was studied.It is found that the pollution height and equivalent particle radius of superhydrophobic coating are much higher than those of silicone rubber.Meanwhile,it is found that the pollution flashover voltage of superhydrophobic coating has an intermediate excessive stationary state,where there is no such phenomenon on silicon rubber and RTV coating surface.The relationship between the surface pollution micromorphology of different hydrophobic materials and the equivalent resistance of the pollution layer is revealed.Based on Obenaus pollution flashover model,a pollution flashover model considering pollution microtopography was established.Finally,a new method of self-cleaning superhydrophobic surface assisted by electric field is proposed.Based on the model of pollution aggregation in electric field,a model of pollution aggregation and self-escaped on superhydrophobic surface in electric field was established.The dynamic process of pollution aggregation and self-escaped of superhydrophobic surface in electric field was studied by means of finite element simulation.The accuracy and validity of this simulation theory are verified by comparing the simulation results with the experimental results.Compared with the traditional superhydrophobic self-cleaning method and the electric field-assisted superhydrophobic self-cleaning method,it is found that the electric field-assisted method directly acts on pollution and has less dependence on the environmental humidity.The feasibility of this new method for efficient self-cleaning at low humidity and heavy pollution on superhydrophobic surface was verified by experiments.