![]() ![]() In 2014, the 200 kV hybrid HVDC breaker was developed which adopted electromagnetic isolation energy supply technology it includes a 200 kV HIET and a 100-level distributed power supply magnetic ring. At present, hybrid HVDC breakers generally use electromagnetic isolation energy supply technology. The 80 kV hybrid DC circuit breaker prototype developed by ABB in 2012 uses a laser power system and achieves high-potential isolation through optical fibres, however, it has high cost and low reliability. The hybrid HVDC breaker's ultra-fast mechanical disconnector and power electronic components are located at a high potential platform, while its energy supply system is located at the grounding potential, so the voltage isolation between high potential and ground potential must be solved. The hybrid HVDC breaker composed of an ultra-fast mechanical disconnector and power electronic components has become the mainstream technology in the development of HVDC breakers due to the advantages of fast breaking speed, flexible controllability and low loss. The HVDC breaker is key equipment for DC system fault clearing and operation mode switching, which is of great significance in ensuring system safe operation. The HVDC grid based on VSC-HVDC technology provides efficient and flexible solutions for improving the consumption of large-scale renewable energy such as wind and light, and promoting energy reform. The 50 0kV HIET prototype has been manufactured and passed the type test, and successfully applied to the 500 kV Zhangbei DC grid project. In addition, the 500 kV HIET's electric field has been analysed. When at 70☌, the inner shielding electric field is much higher than coil shielding, and undergoes obvious reversal. ![]() The electric field is closely related to temperature, when at 20☌, the electric field between double-shielding is relatively uniform. When the thickness is greater than 25 mm, the electric field reduction effect is significantly weakened. The simulation analysis of an electric field at different insulation thicknesses and temperatures shows that the electric field decreases with an increase in thickness of insulation. High-voltage (HV) winding of ST adopts double-shielding structure of coil semi-conductive shielding and inner semi-conductive shielding to improve electric field distribution. The design of a 500 kV HIET with dry-type insulation is proposed, using 10 cascade connected 50 kV sub-transformers (STs), which uses silicon rubber suitable for DC voltage as the main insulation material. There is a lack of research results that can meet engineering applications at home and abroad. The high-voltage isolated energy supply transformer (HIET) is the key component of the HVDC breaker, which is used for energy transmission and the potential isolation. ![]()
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