Method for defending periodic commutation failures of one-tower double-circuit DC transmission system

Abstract

The invention provides a method for defending periodic commutation failures of a one-tower double-circuit DC transmission system. The method comprises the following steps that (I) an inverter station determines a descent rate of voltage amplitude values according to instantaneous values of grid-side three-phase AC voltages; (II) changes of grid-side voltages are judged by using a sine and cosine component detecting method and a zero-order voltage method; (III) a turn-off angle added value and a turn-off angle returned time constant are determined by using a turn-off angle logic method, and a trigger angle is reduced through a turn-off angle controller; (IV) a rectification station puts instantaneous current control into a commutation failure recovery process. The method for defending the periodic commutation failures of the one-tower double-circuit DC transmission system can effectively prevent periodic commutation failures from occurring to a DC transmission system, and DC blocking accidents are prevented from occurring.

Description

technical field [0001] The invention relates to a method in the technical field of power transmission and distribution, in particular to a method for defending against periodic commutation failures in a double-circuit DC power transmission system on the same tower. Background technique [0002] After the thyristor valve period in the 1970s and 1980s, power electronics technology has greatly developed DC transmission, and has shown more advantages in the interconnection of large power grids. The traditional pure AC power grid has developed into an AC-DC hybrid power grid; Conventional power grid commutation HVDC (Line-Commutated-Converter High Voltage Direct Current, LCC-HVDC) with thyristors as commutation components has gained rapid worldwide popularity due to its large-capacity, long-distance power transmission, fast and controllable active power, etc. development of. [0003] Commutation failure is a common transient fault process when the converter composed of semi-cont...

AI Technical Summary

Problems solved by technology

[0003] Commutation failure is a common instantaneous fault process when the converter composed of semi-controlled thyristors is in the inverter working state. If the AC system fault occurs in the vicinity of the inverter station, the instantaneous commutation failure of the DC system is unavoidable.

At present, in the Linfeng DC transmission project erected on the same tower, the voltage drop method used to detect commutation failure has a slow start time and cannot effectively avoid DC commutation failure. In addition, due to the instantaneous current control in the DC control of the rectifier station, the commutation is in the recovery process DC overshoot can easily lead to periodic commutation failure, and the risk of DC blocking caused by commutation failure is significantly increased

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