Three-phase unbalance detection method based on improved S transform

Abstract

The invention presents a three-phase unbalance detection method based on improved S transform, which can improve the detection speed and accuracy of fundamental wave amplitude and phase information and enhance the detection effect of three-phase unbalance of the system. The detection method includes the following steps: sampling real-time signals of the three phases of voltage of a power grid; extracting the fundamental components in the voltage signals through improved S transform to get the vectors (Ua, Ub, Uc) of the three phases of fundamental voltage, wherein the improved S transform refers to that two regulation factors are introduced to the Gaussian window expression of the traditional S transform to form two degrees of freedom so the time-frequency resolution can be flexibly regulated; calculating the positive-sequence, negative-sequence and zero-sequence components (Up, Un, U0) of three phases of fundamental voltage through a symmetrical component method according to the vectors (Ua, Ub, Uc) of the three phases of fundamental voltage; and calculating the system unbalance according to the positive-sequence, negative-sequence and zero-sequence components (Up, Un, U0) of three phases of fundamental voltage.

Description

technical field [0001] The invention belongs to the detection technology of power quality problems, and in particular relates to a detection method of three-phase unbalance degree in a power system. Background technique [0002] With the development of the power system, the types of loads in the distribution network are becoming increasingly complex, and the mixed use of single-phase and three-phase loads makes the problem of voltage imbalance in the distribution network increasingly serious. The three-phase unbalance of the system will lead to the increase of loss, voltage over-limit operation and other problems. Serious three-phase unbalance even endangers the safety of the system. Therefore, it is very important to detect the unbalance degree of distribution network accurately and quickly. [0003] At present, the national standard has relevant regulations on the calculation method of the unbalance degree of the three-phase voltage of the system. Existing detection met...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problems of slow detection speed and poor anti-harmonic ability of existing detection methods, this invention proposes a three-phase unbalance detection method based on improved S-transform, which is applied to three-phase unbalance by improving the traditional S-transform Detection, which improves the detection speed and accuracy of the fundamental amplitude and phase information, thereby enhancing the detection effect of the three-phase unbalance of the system

Images