Direct current control function strategy optimization method and device based on commutation failure prediction

Abstract

The invention discloses a direct current control function strategy optimization method and device based on commutation failure prediction, and the method comprises the steps: 1, carrying out the subtraction between a commutation bus voltage obtained in real time and a commutation bus voltage initial value, and obtaining a commutation bus voltage drop amplitude; step 2, judging whether the voltage drop amplitude of the commutation bus is greater than 1-, which is a voltage threshold value for commutation failure prediction control; step 3, if the voltage drop amplitude of the commutation bus is greater than 1-, controlling commutation failure prediction to start, sequentially performing gain, amplitude limiting and time delay on the voltage drop amplitude of the commutation bus, and outputting an additional trigger angle; and step 4, adjusting a prediction gain coefficient of commutation failure prediction control. By adjusting the prediction gain coefficient of commutation failure prediction control, a plurality of parameters are optimized and adjusted at the same time, so that the improvement effects of the reactive characteristics of the inverter station are further superposed.

Description

technical field [0001] The invention belongs to the technical field of AC / DC hybrid power grids, and in particular relates to a DC control function strategy optimization method and device based on commutation failure prediction. Background technique [0002] The AC / DC hybrid power grid is a typical nonlinear system, and the AC / DC interaction coupling under the impact of large disturbances makes the transient response process of the hybrid power grid very complicated. Therefore, the DC control function usually needs to be optimally set according to the characteristics of the connected grid. [0003] Commutation failure is one of the most common failures of inverters. When the commutation between the two bridge arms is over, if the valve that has just exited conduction fails to recover the blocking ability within the time of reverse voltage action, or the commutation process has not been completed during the reverse voltage period , in both cases, when the valve voltage turn...

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Problems solved by technology

Among them, 1. The pre-judgment based on the commutation voltage only considers the influence of external factors such as the commutation voltage, and uses its characteristic changes as the basis for the pre-judgment, but does not fully consider the control characteristics of the DC system; it only judges the severity of the fault , instead of judging the risk of commutation failure, resulting in a large number of false starts and missed starts in the current commutation failure prevention module

2. In the judgment based on the cut-off angle, the method of using the measured arc-extinguishing angle signal is to detect the negative zero-crossing voltage through the thyristor voltage detection board, and send the zero-crossing voltage signal to the valve base electronic device ((VBE) to generate the valve current overshoot. The zero signal is compared with the zero-crossing signal of the phase-locked voltage to obtain the cut-off angle, but this scheme relies on the zero-crossing signal of the current, and the sensitivity is easily affected, and this method does not belong to the prediction in the strict sense; the arc-off angle prediction The judgment method predicts the commutation failure phenomenon and calculates the commutation failure margin by comparing the inherent turn-off angle with the predicted turn-off angle. However, the current calculation of the predicted turn-off angle is based on the prediction of the DC current under the quasi-steady state model. There may be large deviations in the calculation of the system in a transient state, and the prediction accuracy is limited, making it difficult to provide reference for subsequent prevention and control

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