In the conventional high voltage direct current transmission system with large-scale new energy access

when commutation failure or DC blocking occurs at the receiving end

the reactive power surplus at the sending converter station may cause overvoltage in the AC system. In order to suppress the overvoltage at the sending end

an overvoltage suppression device is proposed based on the principle of controllable energy dissipation. Firstly

the overvoltage mechanism in weak AC system under the fault of DC system is analyzed

and the topology and working principle of the controllable energy dissipation device are proposed. Secondly

the suppression effect and electrical stress of the controllable dissipation device on AC system overvoltage under typical fault conditions is simulated and studied. Then

the design of the controllable dissipation device is carried out

focusing on the potential distribution of the arrester and the the static and dynamic characteristics of electromagnetic repulsion of the trigger switch under different coil turns

the entry and exit control strategy of the dissipation device is proposed. Finally

the experimental verification of the energy dissipation device prototype is carried out

proving the correctness of the design. The energy dissipation device developed is successfully applied to the ±800 kV Lu-Gu high voltage direct current transmission project

and the operation results show that the controllable energy dissipation device can effectively suppress of AC overvoltage.