Analysis Of Main Insulation Structure Of Commutating Transformer With 1000kV Computational Research

With the rapid development of China's power system and the continuous improvement of the voltage level,the DC transmission system has been rapidly developed due to its many advantages.In particular,HVDC transmission has been achieved with its unique advantages of large-capacity and long-distance transmission.Great development.At present,the main UHVDC transmission lines are all connected to the 500kV power grid,and the UHVDC is directly connected to the 1000kV UHV AC grid at the receiving end.The UHV power grid can be fully used as a power receiving and distribution platform to reduce the impact on the 500kV power grid.Effectively enhance system stability.It has a major role in many areas,such as socio-economic aspects,practical engineering applications,and technological innovation.In this paper,the insulation distance is increased on the basis of the insulation structure of the angle ring-paper barrel body of Siemens' commutative manufacturing system,and the number of corner ring cylinders is increased.The insulation structure design of the body side of 1000kV and±400kV converter transformer side is carried out.The following points were simulated and analyzed using the three-dimensional professional electric field calculation software ELECTRO and ELECNET.1.In terms of analysis of the coil wave process of 1000kV converter transformer on the network side,if the voltage on the grid side rises to 1000kV,it means that the level of lightning surge on the grid side will be improved and the number of turns on the grid side coil will also increase.Therefore,based on the ABB manufacturing system coil structure and in accordance with the increase of the test voltage,the net-side coil adopts a plurality of combined flat wires and is designed around the structure type of the first-end insertion correction.The valve side winding throws a classic inner shield continuous structure.2.Analysis of the main insulation structure of the 1000kV converter transformer body on the network side,the special working conditions of the converter transformer determine that its main insulation withstands all the electric field effects of the AC transformer and the electric field under the test voltage,and it also has to withstand DC electric field during the normal operation,the polarity reversal voltage at the time of accident and reverse operation,and the DC electric field under the DC test voltage.Based on the insulation structure of the Siemens classic commutation design and manufacturing system,we increase the insulation distance appropriately and increase the number of angle rings,and design the network-side 1000kV,valve-side±400kV transformer body insulation structure,and submit DC electric field simulation calculations including grid-side induced electric field calculations,valve-side AC electric field calculations,and valve-side DC electric field calculations.3,During the analysis of 1000kV net side lead insulation structure,the net side lead insulation device of the converter transformer is a multi-dielectric,complex shape lead insulation structure composed of oil and paper insulation,metal electrodes and supporting components,and it takes into consideration the lead to the winding,iron core,and the insulation distance between the clamps and the fuel tank.It also needs to calculate the electric field distribution of the high field strength region leads,such as the oil pressure gap at the casing and the voltage at the winding connection line.4,The analysis of the side lead insulation structure of the side 1000kV commutation valve is that the valve side winding is located on the side of the core,so only the axial exit of the end can be adopted.Since the side 1000kV needs a large insulation distance,the valve side winding will cause pressure to a certain extent on the insulation distance of the internal grounding structure such as iron cores and clips,thus causing the valve side insulation space to be tight.This project needs to design the axial exit wire insulation structure of the±400kV end of the valve side,and conduct a detailed check and calculation of its three-dimensional electric field.According to the calculation results,the insulation structure is optimized,and the insulation structure of the lead wire that meets the design requirements is finally modified.