Single-phase voltage sag quick detection method based on morphological filter and derivation method [Alpha][Beta]-dq transformation

Abstract

The invention discloses a single-phase voltage sag quick detection method based on a morphological filter and derivation method [Alpha][Beta]-dq transformation. The method comprises the following steps that: S1: adopting a structural element of which the cosine shape and the triangle are combined according to a certain ratio to carry out primary filtering on a detected single-phase voltage signal;S2: using a signal subjected to primary filtering through a combined-form filter for derivation, and constructing [Alpha][Beta] phase voltage; S3: using a cosine-form filter to filter noise signal interference amplified by differentiate operation; S4: on the basis, through dq transformation, using a linear type filter to filter a non-direct-current amount from a dq transformation result; and S5:calculating the amplitude and the phase angle of voltage sag. By use of the method, the amplitude, the time of duration and the phase change of the voltage sag can be quickly and accurately detected.

Description

technical field [0001] The invention relates to the field of voltage sag detection, in particular to a single-phase voltage sag rapid detection method based on a morphological filter and a derivative method αβ-dq transformation. Background technique [0002] The power quality problem has always been a hot topic in power system research. With the continuous progress of smart grid construction and the continuous improvement of technology in the field of electrical automation, people's requirements for power supply quality have gradually increased. Voltage sag, also known as voltage sag, is the most common and serious type of transient power quality problems, and it will cause huge economic losses every year. Relevant studies have shown that economic losses caused by voltage sags account for all power 70%~90% of quality problems. Aiming at the voltage sag problem, the dynamic voltage restorer (DVR) is a common device that compensates the power quality of the system in time whe...

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Problems solved by technology

The effective value detection method can accurately detect the depth of the voltage sag, but it cannot give the phase jump when the voltage sag occurs, and there is a long detection delay

Most complex algorithms based on frequency domain analysis, such as wavelet transform, Fourier transform, and HHT transform, have their own limitations due to factors such as large amount of calculation and difficulty in engineering.

The dq transformation method is a coordinate transformation method based on the instantaneous reactive power theory. Compared with other algorithms based on the transformation domain, it has the advantages of simple principle, small amount of calculation, and strong real-time performance. However, the traditional dq transformation method can only be applied to The detection of three-phase symmetrical voltage sags, but the actual voltage sags are mostly single-phase faults

The common dq transformation method improved for single-phase faults is mostly a method of delaying a certain angle on the basis of the original signal, such as a delay of 90°, and then using αβ-dq transformation and a delay of 60° to construct a virtual three-phase voltage, but the delay angle is equivalent to The detection delay is artificially increased, which inevitably affects the real-time performance

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