Method for carrying out failure protection and logic optimization on UHVDC (Ultra-High Voltage Direct Current) neutral bus switch

Abstract

The invention discloses a method for carrying out failure protection and logic optimization on a UHVDC (Ultra-High Voltage Direct Current) neutral bus switch. In the operating process of double poles, once the neutral bus switch of a failure pole fails, firstly the operation of detecting whether a basis pole isolation signal exists is carried out, the operation is completed if the basis pole isolation signal does not exist, and the following steps are carried out if the basis pole isolation signal exists: 1, sending a command to make the neutral bus switch coincided and locked; 2, switching off an instation neutral bus earthed switch; 3, separating an isolation switch near the neutral bus switch of the failure pole; and 4, after the isolation switch is separated and is in place, switching off the instation earthed switch. After the processing method is adopted, when the neutral bus switch fails, the failure pole can still be isolated, so that the operation stoppage of the double poles is effectively avoided.

Description

technical field [0001] The invention relates to an action strategy for neutral bus switch failure protection of an UHV direct current transmission system and a protection device adopting the strategy. Background technique [0002] In the UHV DC transmission system, since the DC current does not have a zero-crossing point like the AC current, the breaking capacity of the DC circuit breaker is limited and depends on its own auxiliary circuit. Configure a DC circuit breaker on the bus side for pole isolation operation, namely figure 1 In the neutral bus switch (NBS), when the neutral bus switch fails to operate, that is, when the switch fails, if the appropriate handling method is not adopted, it may cause bipolar outage. The neutral bus switch failure protection criteria are as follows: [0003] After the neutral bus switch NBS receives the trip command for a period of time, the IDNE current exceeds a certain value, and the neutral bus switch failure protection action. [00...

AI Technical Summary

Problems solved by technology

[0005] After the neutral bus switch failure protection action, in order to prevent the neutral bus switch from being damaged, it is necessary to reclose the neutral bus switch. If the neutral bus switch is reassembled and locked, the fault cannot be isolated, which may cause the non-faulty pole to be out of service.

Due to the huge transmission capacity of UHV DC, once a bipolar outage occurs, the impact on the AC system will be very large, and the interruption of transmission power will also bring huge losses to the national economy

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