Single‐end time‐domain transient electrical signals based protection principle and its efficient setting calculation method for LCC‐HVDC lines

In view of the facts that existing line commutated converter based high voltage direct current (LCC‐HVDC) line protection cannot realise satisfactory selectivity, speed, sensitivity, reliability and practicability simultaneously, and that the work of setting calculation for line protection is very onerous and time‐consuming due to extremely large amounts of electromagnetic transient simulations, a novel single‐end time‐domain transient electrical signals based protection principle incorporating all these satisfactory features and its efficient setting calculation method are proposed. For the proposed protection principle, the DC line current change criterion is employed as a directional element, which can identify faults in the positive direction of line protection, while the rate of voltage change criterion is used as a boundary element, through which the opposite internal and external faults can be distinguished. Moreover, an efficient setting calculation method is proposed based on a so‐called ‘setting calculation preparation quantity’ concept, through which the setting calculation values can be determined efficiently based on only several simulations by systematically analysing the impact of various operating conditions on the post‐fault transient electrical signals of LCC‐HVDC systems. Finally, the simulation result based on a ±800 kV ultra‐HVDC practical model verifies the validity of the proposed protection principle and its efficient setting calculation method.