CN-115932366-B - Voltage sag detection method with speed and anti-interference capability

Abstract

The invention discloses a voltage sag detection method with speed and anti-interference capability, and relates to the technical field of circuit device control of an alternating current transmission and distribution network. The invention provides a new method for detecting voltage sag, which can rapidly and reliably detect the voltage sag by adopting a voltage effective value rapid algorithm under the condition of not changing the original hardware equipment.

Inventors

• Huang Liejiang
• ZHANG CHI
• MA YAN
• LI JUNFEI
• JIN LEI
• ZUO XIAOFANG
• CHEN SICHAO
• SHEN DILONG
• DAI JIANGANG
• PAN GUORONG
• ZHU HAIYAN
• ZHOU GUOHUA
• LV WEI
• SHEN LIHUA

Assignees

• 杭州欣美成套电器制造有限公司
• 国网浙江杭州市萧山区供电有限公司
• 浙江晟泰电气有限公司

Dates

Publication Date

20260512

Application Date

20221201

Claims (4)

1. 1. A voltage sag detection method with speed and anti-interference capability is characterized in that a voltage amplitude Urms is calculated through 1/4 cycle voltage, and the calculated voltage amplitude is continuously and repeatedly judged whether the voltage amplitude belongs to a low-voltage working condition of a system or not; The amplitude Urms of the system voltage is calculated by Sin delta and Cos delta of a root mean square value U1/4rms of 1/4 cycle and a phase angle delta, wherein the Sin delta and the Cos delta can be calculated in real time by a phase-locked loop; assuming that the single-phase voltage is (1) Wherein U rms is the effective value of the voltage period; the 1/4 period voltage root mean square value can be expressed as (2) Wherein U 1/4rms is the effective value of 1/4 period of voltage, delta is 0 to Any one value in between; Substituting formula (1) into formula (2) (3) Obtainable from (3) (4) Due to (5) Are available in combination with (4) and (5) (6) From the equation (6), it can be seen that U rms , sin delta, cos delta can be obtained by the phase-locked loop in real time as long as U 1/4rms , sin delta, cos delta are obtained, and U 1/4rms can be obtained from the equation (7) (7)。
2. 2. The method for detecting voltage sag according to claim 1, wherein the effective value Urms of the system voltage is calculated.
3. 3. The method for detecting voltage sag according to claim 1, wherein the system voltage amplitude is calculated through a 1/4 cycle sliding window.
4. 4. The method for detecting voltage sag according to claim 1, wherein the delay time is 2ms when the method is used for detecting 90% of voltage sag actually used in engineering.

Description

Voltage sag detection method with speed and anti-interference capability Technical Field The invention relates to the technical field of circuit devices of alternating current transmission and distribution networks, in particular to a voltage sag detection method with speed and anti-interference capability, and relates to a low voltage detection judgment process of a dynamic voltage restorer DVR (Dynamic Voltage Restorer) device. Background In power systems, short circuit faults, large capacity induction motor start-up, transformer investment and lightning strokes are the main causes of voltage sag. Along with the high-speed development of economy, precision complex electronic equipment is increasingly widely applied in modern industry, and most of the complex electronic equipment is sensitive to short-time voltage sag, and the normal operation of sensitive equipment is affected by power supply voltage sag and interruption of only tens of milliseconds, so that huge economic loss and safety hazard are brought. Therefore, voltage sag and interruption have become the most important electric energy quality problems in various fields, seriously threaten the rapid development of the normal electricity consumption, the safe electricity consumption and the national economy in the modern society, and are new challenges facing power grid companies and industrial and commercial power users. Disclosure of Invention The invention mainly solves the defects existing in the prior art, and provides a method for calculating the voltage amplitude U rms through the voltage of 1/4 cycle and continuously judging whether the calculated voltage amplitude belongs to the system low-voltage working condition or not for many times. The method gives consideration to the requirements of DVR on speed and anti-interference capability, and can be well applied to the actual engineering of the voltage amplitude sag detection. The technical problems of the invention are mainly solved by the following technical proposal: A voltage sag detection method with speed and anti-interference capability is disclosed, wherein the voltage amplitude Urms is calculated through 1/4 cycle voltage, and the calculated voltage amplitude is continuously and repeatedly judged whether the system belongs to the low voltage working condition. Preferably, the effective value Urms of the system voltage is calculated. Preferably, the amplitude of the system voltage is calculated through a 1/4 cycle sliding window. Preferably, the magnitude Urms of the system voltage is calculated from the root mean square value U1/4rms of the 1/4 cycle and the Sin delta, cos delta of the phase angle delta, wherein Sin delta, cos delta can be calculated in real time by a phase-locked loop. Preferably, the delay is 2ms for detecting a 90% voltage dip that is actually used in engineering. Preferably, it is assumed that the single-phase voltage is (1) Wherein U rms is the effective value of the voltage period. The 1/4 period voltage root mean square value can be expressed as (2) Wherein U 1/4rms is the effective value of 1/4 period of voltage, delta is 0 toAny one value in between. Substituting formula (1) into formula (2) (3) Obtainable from (3) (4) Due to (5) Are available in combination with (4) and (5) (6) From the formula (6), U rms can be obtained by simply obtaining U 1/4rms and Sin δ, cos δ. Sin delta and Cos delta can be obtained in real time by a phase-locked loop, and U 1/4rms can be obtained by the formula (7). (7)。 The dynamic voltage restorer DVR (Dynamic Voltage Restorer) gradually becomes the most effective and economical power equipment for treating the voltage sag problem with the advantages of large compensation range, high efficiency, better economy, reliability and the like. As one of the key technologies in the DVR, the fast and accurate voltage sag detection technology is critical to the compensation effect of the DVR. Up to now, various voltage sag detection methods have been proposed, mainly including an effective value algorithm, a peak voltage method, a defect voltage method, a single-phase voltage derivative method, a dq conversion-based algorithm and an improved algorithm thereof, and the like. The effective value algorithm is simple to calculate, easy to implement and high in noise resistance, but the method at least needs half cycle historical data, is poor in instantaneity, and cannot give out the starting and ending time of voltage sag and cannot calculate possible phase jump. The peak voltage method is simple in principle and convenient to implement, and can quickly detect the recovery of voltage after the sag is ended, and can reflect the start and stop time of the occurrence of the voltage sag. However, the method requires half a period of time to acquire the dip information, and the detected dip amplitude value is generally larger than the actual value, so that a larger error occurs in the detection result under the condition that the dip amplitude valu