Voltage sag detecting method suitable for dynamic voltage restorer

Abstract

The invention belongs to the field of electric system state monitoring, and particularly relates to a voltage sag detecting method suitable for a dynamic voltage restorer. The method includes the steps of establishing phase shifting components through the three selected detection points which include the front detection point, the middle detection point and the rear detection point and are arranged at equal intervals, obtaining a d-axis DC component and a q-axis DC component of a fundamental wave through a Butterworth low-pass filter after alpha beta-d q conversion is conducted on the detection points and a middle sampling point, conducting quadratic sum addition on the d-axis DC component and the q-axis DC component and calculating through a root-mean-square to obtain a voltage amplitude, conducting arc-tangent function operation on the quotient obtained by dividing the q-axis DC component by the d-axis DC component, and obtaining a phase jump angle through the difference between the phase detection value at the earlier moment and the phase detection value at the later moment. By means of the method, the certain white noise resistance is still achieved while the real-time requirement is met, and the method is quite suitable for detecting voltage sags in the dynamic voltage restorer.

Description

technical field [0001] The invention belongs to the field of power system state monitoring, and in particular relates to a voltage sag detection method suitable for a dynamic voltage restorer. Background technique [0002] Dynamic Voltage Restorer (Dynamic Voltage Restorer, DVR) is an effective series compensation device used to ensure the stability of sensitive load power supply voltage. It can inject a voltage with adjustable amplitude and phase in series between the system and the load within milliseconds. Compensate for voltage sags, so as to ensure that the voltage of sensitive loads is still within an acceptable range when disturbed by the system voltage. [0003] In order to meet the real-time requirements of detection, DVR generally adopts a detection method based on dq transformation. Most of the actual voltage sag accidents are single-phase events. In order to apply dq transformation in the single-phase system, it is necessary to construct a virtual three-phase sy...

AI Technical Summary

Problems solved by technology

The first two phase-shifting construction methods above require a large delay, which cannot fully meet the real-time requirements of detection. Although the derivation construction method has excellent fast response characteristics, it has overshoot and is resistant to white noise. Due to the characteristics of poor performance, although the delay delta angle method ensures a good fast response characteristic, it inevitably has an amplification effect on harmonics and noise

[0005] The above-mentioned various detection algorithms based on αβ-dq transformation generally use software phase-locking technology to genlock the voltage signal to be measured. Phase technology cannot achieve dynamic tracking

Images