A longitudinal protection method that automatically adapts to the power reversal of transmission lines

Abstract

The invention discloses a pilot protection method for automatically adapting power converse of a power transmission line. The pilot protection method comprises the following steps: utilizing protected identification elements in forward and backward directions to judge whether the power transmission line is in the condition of power converse according to the sequence of actions of the elements in forward and backward directions; calculating external fault breaker opening time and permissive command pilot protection channel transmission time, and when the power transmission line is judged to be in the condition of power converse, processing the two time to form an additional time delay, so that faulty action does not occur during the power converse through the additional time delay of pilot protection; when the power transmission line is judged to be not in the condition of power converse, not adding the additional time delay of pilot protection. The pilot protection method can prevent incorrect actions of pilot protection during power converse.

Description

technical field [0001] The invention relates to a method for realizing automatic adaptive power reverse longitudinal connection protection of transmission lines in the field of electric power systems. Background technique [0002] As the structure of the transmission network becomes more and more complex, double-circuit and multi-circuit transmission methods on the same pole and parallel rack have been widely used in ultra-high voltage and ultra-high voltage lines. Such as figure 1 As shown in Fig. 2, when a fault occurs on the second circuit near the exit of the M side, the disconnection time of the circuit breaker on the M side of this line may be earlier than that of the N side circuit breaker. Ⅰ The longitudinal protection of the return line does not operate correctly. With the increasing number of DC lines, the fast action characteristics of DC control and protection in AC-DC hybrid power grids are also prone to power reversal phenomena on AC transmission lines. [0...

AI Technical Summary

Problems solved by technology

[0004] With the development of technology, the opening speed of the circuit breaker is accelerated, and the fast blocking of the DC in the AC and DC network leads to the rapid switching of the power direction. After the fault of the adjacent line, the power reversal will soon occur on the main line, which makes it more difficult to select the TA time. In addition, with the increasing shortage of dedicated channel resources for relay protection, more and more longitudinal protection uses public network channels under special circumstances, and the transmission time of public network channels is relatively long and has no The upper limit is specified, and the TB fixed delay adopted by conventional longitudinal protection cannot adapt to different channel transmission times

Due to the above two reasons, when the power is reversed, the traditional longitudinal protection will malfunction due to the timing coordination problem between the forward direction element and the blocking (allowing) signal.

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