Traveling wave protection method for AC lines on the inverter side of lcc-hvdc

Abstract

The present invention discloses a traveling wave protection method suitable for a LCC-HVDC inverter alternating current line. The method comprises: starting protection according to a three-phase current traveling wave sampling value; respectively capturing T1 and T2 length data windows through a protection unit being close to an inverter and a protection unit being far away from the inverter; performing phase-mode transformation of the three-phase current traveling wave sampling values in the data windows, and obtaining 1-mode current traveling waves, 2-mode current traveling waves, 3-mode current traveling waves and 0-mode current traveling waves; performing integral operation of the 1-mode current traveling waves and the 2-mode current traveling waves at the protection unit being close to the inverter and the protection unit being far away from the inverter, and mutually exchanging the current traveling wave integral values; determining a fault interval according to the obtained current traveling integral values; and combining the fault interval, identifying the amplitudes of the initial waves of the 1-mode current traveling waves, 2-mode current traveling waves, 3-mode current traveling waves and 0-mode current traveling waves to determine fault phases. The traveling wave protection method suitable for the LCC-HVDC inverter alternating current line is high in reliability and fast in motion speed, and has important meaning for improving the safety and stability level of an alternating current / direct current hybrid system.

Description

technical field [0001] The invention relates to a traveling wave protection method suitable for an AC line on an LCC-HVDC inverter side. Background technique [0002] With the continuous expansion of the scale of the power system, a large number of large-capacity AC-DC hybrid systems have been constructed, which have long transmission distances, large transmission capacity, and high transmission efficiency. However, due to the special structure and control strategy of the current source high-voltage direct current transmission (LCC-HVDC) inverter station, its normal operation is easily affected by the fault of the AC line on the inverter side. If the fault cannot be removed quickly, it will easily lead to commutation failure. It may even lead to DC blocking. The traveling wave protection has fast action speed, strong ability to withstand transition resistance, and can respond to various fault types. If the traveling wave protection is configured as the main protection of t...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problem that the traditional traveling wave protection method is no longer applicable or has poor reliability, the present invention proposes a traveling wave protection method suitable for the AC line on the inverter side of LCC-HVDC. The present invention fully considers the special characteristics of the AC line on the inverter side Traveling wave refraction and reflection characteristics, identifying faults inside or outside the area, has good applicability, and at the same time uses the integration of current traveling wave signals within a period of time, the protection reliability is high

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