A Fault Recovery Method for Commutation Failure in DC Transmission System

Abstract

The invention discloses a direct current power transmission system commutation failure fault recovery method. The method comprises the following steps of step1, collecting the direct voltage and the direct current of a direct current power transmission system, and the alternating voltage of an alternating current power grid connected to a reverse converter station; step2, according to an analog quantity collected in step 1, determining whether the direct current power transmission system has a commutation failure fault; step3, If the commutation failure fault occurs, making a rectifier converter station increase a firing angle, and making the reverse converter station trip off a direct current circuit breaker, simultaneously using the commutation failure time accumulator of the reverse converter station to start carrying out timekeeping and accumulate commutation failure time; when waiting set time is up or the commutation failure fault disappears within a certain time, making the rectifier converter station reduce the firing angle, making the reverse converter station reconnect the direct current circuit breaker, trying to restore direct current power to a level before the fault and resetting the commutation failure time accumulator of the reverse converter station. In the invention, the commutation failure fault of the direct current power transmission system can be effectively processed, and a condition that a power fluctuation brought by a direct current continuous commutation failure jeopardizes the safety and stability of the connected alternating current power grid is avoided.

Description

technical field [0001] The invention belongs to the field of direct current transmission, and in particular relates to a fault recovery method for a commutation failure of a direct current transmission system. Background technique [0002] The thyristor-based grid commutation HVDC transmission system has large transmission capacity, low line cost, strong asynchronous networking capability, and has great advantages in long-distance large-capacity transmission and large-area networking. The high-density connection of the DC transmission system to the AC grid makes the interaction between the AC and DC systems increasingly complex, and poses a huge challenge to the safe and stable operation of the grid. Commutation failures in high-power DC systems are relatively common, mostly caused by faults in the AC system at the receiving end. During the period of commutation failure, the DC power drops sharply, the synchronous generator of the DC sending-end grid accelerates, and the fr...

AI Technical Summary

Problems solved by technology

For the prediction and preventive control of commutation failure, scholars have proposed a variety of improved prediction algorithms, including methods to improve the detection speed and accuracy near the zero crossing point, and adopt adaptive fuzzy control or PI control to deal with different DC control modes and operating conditions. Influenced by conditions, most of them are increasing the turn-off angle or reducing the DC current, which can be used as an auxiliary preventive method for commutation failure, but it cannot fundamentally avoid the continuous occurrence of commutation failure

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