Adaptive restarting method for LCC-HVDC based on principle of fault location by current injection

The existing LCC-HVDC transmission project adopts the fixed-time delay restarting method. This method has disadvantages such as non-selectivity, long restart process, and high probability of restart failure. These issues cause a secondary impact on equipment and system power fluctuation. To solve this problem, an adaptive restarting method based on the principle of fault location by current injection is proposed. First, an additional control strategy is proposed to inject a current detection signal. Second, the propagation law of the current signal in the line is analyzed based on the distributed parameter model of transmission line. Finally, a method for identifying fault properties based on the principle of fault location is proposed. The method fully considers the influence of the long-distance transmission line with earth capacitance and overcomes the influence of the increasing effect of the opposite terminal. Simulation results show that the proposed method can accurately identify the fault properties under various complex fault conditions and subsequently realize the adaptive restarting process.