Abstract With the upgrade of the voltage level, flexible DC converter valves often adopt multi-layer support structure design of the insulators in series, so as to ensure enough insulation interval to the ground. However, in model tests, there was a problem of uneven voltage distribution across the insulator of the commutation valve, making it difficult to select the type of insulator. This will increase the design cost and difficulty of the converter valve. Aiming at ±800 kV DC converter valve tower, this article analysis the uneven voltage distribution in series supporting insulators under the AC-DC insulation type test, established a circuit calculation model and extracted the capacitance and resistance parameters in the model. By comparing with the calculation results of the quasi-static electric field, the correctness of the circuit calculation model is verified. Based on the above, this article put forward a method to make voltage distribution evenly by setting the potential clamp point between the water pipe and the series insulator. In addition, the influence of water pipe length, the number of water pipes connected by equipotential bonding, the number and height of insulator strings and the position of equipotential bonding on the voltage distribution of series supporting insulators were calculated and analyzed. Then combining with engineering design requirements to confirm the voltage distribution scheme on series supporting insulators. The two methods can not only meet the design demand, but also significant save costs and time in designing.
Li Jingyi,Shen Hong,Liu Kexin等. Improving the Voltage Distribution of the Insulator String of Flexible HVDC Converter Valve[J]. Transactions of China Electrotechnical Society, 2018, 33(21): 5128-5135.
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2018, Vol. 33 
