Detection method for electric voltage phase angle jump at network voltage dip

Abstract

The invention discloses a voltage phase angle jumping detection method at the falling time of network voltages, comprising the following steps of: obtaining, by sampling, three-phase network voltages VA(k), VB(k) and VC(k); detecting a voltage angle [gamma] (k) of synchronous rotation of the network voltages at the sampling time; converting the three-phase network voltages into Vd(k), Vq(k) weights under a d-q synchronous rotation coordinates system; taking the Vd(k), Vq(k) weights under the current d-q coordinates system and Vd(k-1), Vq(k-1) weights at the last sampling time as known quantities, and calculating to obtain an amplitude |V1(k)| of a current positive-sequence weight and a sine and cosine value thereof with a d axis included angle [theta]1(k); directly using an amplitude |V2(k)| of a negative-sequence weight and the sine and cosine value thereof with a d axis included angle [theta]2(k) for the control and calculation subsequent to the falling malfunction of the voltage; or implementing an inverse trigonometric operation on the sine and cosine values of the[theta]1(k) and the[theta]2(k) according to practical requirements so as to obtain voltage positive / negative-sequence phase angle variable quantities [delta][phi]+ and [delta][phi]- that occur on account of the falling of the voltage.

Description

technical field [0001] The invention relates to a method for detecting voltage phase angle jumps at the time of grid voltage drop, belonging to the field of electrical control. Background technique [0002] Voltage sag is the most common fault in the power grid. There are three-phase symmetrical faults and asymmetrical faults such as single-phase and two-phase ground faults and phase-to-phase faults. The depth of the voltage drop varies, the lowest can be zero, and the duration is from 0.5 grid voltage cycle to several seconds. According to the basic principle of the circuit, any three-phase AC voltage (current) can always be decomposed into the sum of positive sequence, negative sequence, zero sequence and other components. When the AC voltage or current is three-phase balanced (that is, the amplitude of the three phases is equal, the phase difference is 120°, and the positive direction rotates), it only contains positive sequence components; when the grid voltage has an a...

AI Technical Summary

Problems solved by technology

[0007] The technical problem to be solved by the present invention is: to overcome the shortcomings of the existing detection method for voltage phase angle jump when the grid voltage drops, and to provide a detection method for voltage phase angle jump when the grid voltage drops with a simple algorithm and a wide range of application

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