An optimization method for predictive control of commutation failure in DC control and protection systems

Abstract

The invention discloses an optimization method for commutation failure prediction control of a DC control and protection system. The zero-sequence voltage 3U0 signal of a commutation bus in an inverter station is input into a fast Fourier converter, and the fundamental wave component is separated, and the obtained The fundamental wave component is compared with the setting value, and when it is less than the setting value, it outputs 1, otherwise it outputs 0; at the same time, the action signal Z_DET is input into the monostable multi-frequency oscillator, and the corresponding time setting value is set to maintain the action signal Z_DET In the high position, the output is delayed by the delay component; the above two signals are jointly output to the two-way input selector through the AND gate as the action criterion Ctrl. The present invention is used to effectively distinguish single-phase faults and excitation inrush current disturbances, so that when a single-phase fault occurs on the AC side, the control logic operates reliably; when there is an excitation inrush current on the AC side, the control logic can effectively identify, and Suppress repeated fluctuations in DC power.

Description

technical field [0001] The invention relates to a direct current control and protection system, in particular to an optimization method for commutation failure prediction control of the direct current control and protection system. Background technique [0002] Commutation failure is the most common fault in the inverter station during the operation of the DC transmission system. During the commutation failure period, there will be a sudden drop in the DC voltage and a large drop in the DC power, which has a serious adverse impact on the power grid at the sending and receiving ends. The reasons for commutation failure include the following two points: one is the failure of the DC transmission system itself, such as valve short circuit and loss of trigger pulse; the other is the voltage fluctuation of the commutation bus caused by the failure of the AC system. In the DC control and protection system, there is a corresponding commutation failure predictive control (CFPREV) to ...

AI Technical Summary

Problems solved by technology

[0005] None of the above methods can solve the problem that the existing CFPREV control logic cannot distinguish excitation inrush current disturbances from single-phase faults, and has the disadvantages of poor anti-harmonic ability and easy to cause DC power fluctuations

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