| The external insulation pollution flashover of electric transmission and transformation equipments is the main threat to the safe operation of the power system. Hot washing is an important technical means to avoid pollution flashover. Nowadays it has been widely used at220kV voltage level below. However, hot washing of500kV substation equipments has not been carried out before, and the basic research and engineering practice of500kV hot washing in China are still blank before. This article studied the hot washing technology systematically aming at the500kV transformation equipments including water jet characteristics and cleaning efficiency, water column insulation, post insulator outer insulation and washing methods. The study results have been verified and applied in500kV substation hot washing engineering practice.In the aspects of the water jet characteristics and cleaning efficiency, the structure and morphology of water jet are simulated by software FLUENT and observed using high-speed photography combined with the dynamics basic theories of the water jet. The rich morphology at different distance and the velocity field distribution of water jet, the diameter of the water column can be achieved from the observation. the structural model of water jet is proposed. The water column hitting force test method as well as cleaning efficiency test method are proposed, and the testing devices are built. The quantitative relationships between hitting force as well as cleaning efficiency with nozzle diameter, water pressure, water column length and washing angle are gotten. The evaluation methods of cleaning efficiency and hot washing process are proposed, and the quantitative relationships between cleaning efficiency including residual ESDD ratio and residual NSDD ratio with contamination degree, water column length, nozzle diameter, pressure,washing angle and insulators are analyzed.In the aspect of water column insulation, power frequency leakage current and operating impulse discharge properties test of the water column are carried out. The quantitative relationships between power frequency leakage current of the water column and water resistivity, water column length, nozzle diameter and pressure are gotten. So are the quantitative datas about switching impluse voltage discharge voltage with water column length and water presure. The water column length ensuring safe insulation of500kV hot washing are raised. The experiments prove the rationality of the regulations. In the aspect of hot washing methods of post insulators insulation, the method that can evaluate the safety of the post insulator insulation characteristics during hot washing basing on the insulator surface used leakage current waveform properties. The safety quantitative comparison under different kinds of washing methods with three-gun and four-gun is carried out. The leakage current amplitude curves during the washing process and the characteristics of leakage current in different washing stages are gotten for the first time.In the aspect of hot washing equipments exploitation and application, based on the robot control strategy and hotogrammetry tenchnology, a hot washing equipments operated by robot on the cart and trolley-car in coordination with human beings.Serval operation modes have been proposed including washing by robots loaded on two carts, washing by four workers loaded on a cart and so on. These equipments not only realize the hardware integration, but also solve many crucial technology problems. It contributes to the improvement of operation security and the automation level in large scale.Recommended methods are verified to be effectiveness and security used in the outdoor charged water washing test site and500kV substation. Power industry standard named "Hot washing Technical guide for500kV Transmission and Transformation Equipments" has been completed draft version. |
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