Structural Design and Test of 500kV Dry-Type Air-Core Shunt Reactor with Encapsulated Coil Series Connection

In order to meet the technical requirements of high inductance, low current, and high terminal voltage for highvoltage parallel reactors, this paper proposes a new scheme of encapsulated coil series dry-type air-core shunt reactors. And the performance parameters and operational stability of the prototype are verified through long-term live assessment tests. The prototype adopts modular design, with each module having the same inductance value and structure, equivalent to a standardized unit of 66 kV dry-type shunt reactor. Each unit consists of 15 encapsulated coils connected in series, and 8 units connected in series to form a 500kV/24MVar shunt reactor. The upper and lower units are fixed with supporting insulators, which can be quickly replaced during installation and maintenance. A new method for calculating the inductance and potential distribution of parallel reactors has been proposed. Under lightning impulse voltage, the voltage distribution between adjacent envelop of the reactor is basically uniform, and the deviation between the calculated and measured results is less than 10%. The lightning impulse withstand voltage at the prototype line end is −1550 kVp, and the switching impulse withstand voltage is 1175 kV<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf>. In the 64 days long-term live assessment test at 318 kV & 92.5 A, the deviation of the electrical impedance value of the prototype is less than 0.25%. The electric field strength at a distance of 2 meters from the prototype is 18.1 kV/m, the magnetic induction strength is 1450 μT, and the sound level is 64.2 dB. At an ambient temperature of 40°C, the maximum surface temperature of the prototype is less than 90°C, and the temperature rise is less than 50 K. This study can provide reference for the research and engineering application of high-voltage dry-type air-core shunt reactors.