An AC fault detection method for HVDC transmission

Abstract

The invention provides an alternating-current fault detection method for high-voltage direct-current power transmission. The alternating-current fault detection method for high-voltage direct-current power transmission comprises the following steps of obtaining the three-phase voltage of a current conversion bus and three-phase currents of outgoing lines of the current conversion bus; obtaining a voltage zero-sequence component value and a rotating vector amplitude of the current conversion bus according to the three-phase voltage of the current conversion bus, and obtaining current zero-sequence component values and rotating vector amplitudes of the outgoing lines of the current conversion bus according to the three-phase currents of outgoing lines of the current conversion bus; obtaining power zero-sequence component values and power rotating vector amplitudes of the outgoing lines of the current conversion bus; comparing the values and the amplitudes with the set values and the set amplitudes respectively to obtain the fault detection result. The alternating-current fault detection method for high-voltage direct-current power transmission is high in speed and accuracy, and meets the requirement of high-voltage direct-current power transmission for fault detection, and valuable information is provided for the defense commutation failure of a control system for high-voltage direct-current power transmission.

Description

technical field [0001] The invention relates to a method in the technical field of power transmission and distribution, in particular to a fault detection method for high-voltage direct current transmission. Background technique [0002] Since the 1950s, the traditional grid commutated high-voltage direct current (Line-Commutated-Converter High Voltage Direct Current, LCC-HVDC) has developed rapidly around the world due to its large-capacity long-distance transmission and fast controllable active power. [0003] However, since LCC-HVDC uses ordinary thyristors without self-shutoff capability as commutation components, the LCC-HVDC system requires a certain strength of the AC system to achieve commutation, and the commutation voltage needs to be provided by the AC grid. When the power grid fails or the three-phase is seriously asymmetrical, the AC bus voltage will drop, the line voltage zero crossing point may be advanced, the commutation overlap angle of the LCC-HVDC valve a...

AI Technical Summary

Problems solved by technology

However, in HVDC transmission, a fault in the vicinity of the commutation bus may cause commutation failure. The fault detection is not for this section of the line, but to detect whether there is a fault near the commutation bus.

If the setting principle of the general circuit breaker action in the power system is followed, there will be problems such as the fault detection range is not wide enough, and the detection time is long.

Moreover, HVDC is used as a harmonic source, and its bus voltage is not completely symmetrical, which makes the voltage output fluctuate to a certain extent. If only voltage is used as a fault criterion, the quickness has to be sacrificed in order to ensure the reliability of the judgment.

Similarly, harmonic currents and asymmetrical currents will affect the amplitude, slope, and curvature waveforms of the current, and the same problem occurs when only current is used as a fault criterion.

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