Amplitude change characteristic-based voltage drop prediction system and method

Abstract

The invention provides a voltage drop prediction system and method based on amplitude change characteristics. The method comprises the following steps: S1, collecting a voltage vector u0 of any phase in a power grid; S2, delaying the acquired voltage vector u0 by any angle to obtain a virtual voltage vector u phi; S3, calculating by using the virtual voltage vector u phi to obtain a voltage vector amplification ud; S4, according to the voltage vector amplification ud, calculating the voltage vector amplification ud1 within the time corresponding to the delayed angle; S5, according to the relationship between the calculated value of the voltage vector amplification ud1 in the time corresponding to the delayed angle and the original amplitude U of the voltage vector, judging a voltage drop result; S6, determining a drop amplitude characteristic table according to the drop result in the S5 and the calculated value of the voltage vector amplification ud1 in the time corresponding to the delayed angle; and S7, carrying out periodic sampling, and judging the generation of voltage sag according to the sag amplitude characteristic table.

Description

【Technical field】 [0001] The invention relates to the technical field of voltage detection, in particular to a voltage drop prediction system and method based on amplitude variation characteristics. 【Background technique】 [0002] As one of the essential energy sources in modern society, electric energy is used in all aspects of production and life. With the rapid development of power electronics technology, a large number of related facilities are gradually used in industrial production and social family life, and the power quality of the power grid will be polluted. In order to meet the requirements of power users for power quality, the research on improving power quality is of great significance. Voltage sag is one of the most serious power quality problems. Effective compensation for voltage sag can increase the stability of power system operation and bring greater economic benefits. Rapid and accurate detection of voltage sag characteristics is an important prerequisit...

AI Technical Summary

Problems solved by technology

[0003] There are many existing technologies for the detection of voltage drop characteristics: the dq0 transformation method based on the instantaneous reactive power theory uses the collected three-phase voltage to transform it into the rotating coordinate system through park, and then calculates the amplitude of the fundamental voltage. However, it is only applicable to the symmetrical drop of three-phase voltage; according to the collected single-phase voltage signal, by constructing a virtual αβ coordinate system with a delay of 90°, the single-phase drop can be effectively detected, but the delay is longer; an improved no-delay The detection method under the time-dq coordinate system. This method constructs a virtual three-phase voltage for detection by performing differential processing on the single-phase voltage. The real-time performance is good, but it will amplify the high-frequency oscillation, and the selection of the filter is very important. ; The method of delaying small angles can speed up the detection speed and has high precision, but for drops at different angles, the voltage amplitude obtained by this method will have different trends, and a delay will occur when using the threshold comparison judgment

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