Real-time detection method for voltage dip
A technology of voltage drop and real-time detection, which is applied in the direction of measurement using digital measurement technology, can solve the problems of poor real-time performance of test methods, and achieve the effect of improving safe operation performance, ensuring normal operation, and good real-time performance
Inactive Publication Date: 2013-11-13
SUZHOU UNIV
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Problems solved by technology
[0005] However, in the detection of voltage drop, the speed of detection is very important. Although the above method can detect the amplitude of voltage drop, the detection process needs at least one cycle, even if the sliding average method is adopted, However, the real-time performance of this test method is still poor
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Embodiment 1
[0028] Embodiment one: see Figure 1~4 Shown, a kind of real-time detection method of voltage drop, its step comprises:
[0029] (1) Sampling the actual city voltage: start the A / D conversion of the CPU every 1ms, and sample the real-time voltage V between the neutral line and the phase line of the mains through the voltage measurement circuit S ;
[0030] The voltage measurement circuit is composed of a full-wave bridge rectifier circuit, a step-down circuit, a filter capacitor and a protection circuit, such as figure 1 As shown, the mains 220V AC voltage is input from L and N. L is the phase line of the mains, and N is the neutral line of the mains. The voltage value between L and N is AC 220V. After bridge stack DB107S full-wave rectification, a DC pulsating voltage is obtained, and then through the voltage division and step-down treatment of resistor R1 and resistor R2, a low DC pulsating voltage is obtained. The low DC pulsating voltage is filtered by capacitor C1 an...
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The invention discloses a real-time detection method for voltage dip. The method comprises the following steps of: 1, sampling actual mains voltage VS; 2, finding a voltage low point Vlow, wherein f is mains frequency, V is the mains maximum value maximally, and t is a time slot where the voltage low point is positioned; 3, continuously sampling the actual mains voltage for ten times by using a voltage measurement circuit at an interval of 1 millisecond after the voltage low point is found; 4; finding the maximum value Vmax from 10 voltages and transforming the maximum value Vmax into an effective value Veffective; and 5, considering that the voltage drops 1T when the effective value Veffective in the step 4 is smaller than the dropout voltage Vdrop, otherwise returning to the step 2, considering that the voltage drops 2T when two continuous voltage effective values are smaller than the dropout voltage, and thus obtaining a voltage dip period accordingly. By sampling the mains voltage in real time, the periodic time of voltage dip can be detected in real time, so a correct measure can be taken after voltage dip is detected by electrical equipment, and the normal running of the electrical equipment is ensured.
Description
technical field [0001] The invention relates to a voltage test method, in particular to a real-time detection method of voltage drop. Background technique [0002] Voltage sag refers to the phenomenon that the amplitude of the voltage suddenly deviates from the normal working range at a certain moment, and returns to the normal level after a short period of time. Studies have shown that the voltage drop problem has become one of the most serious dynamic power quality problems affecting the normal and safe operation of many electrical equipment. [0003] Severe weather conditions are the main cause of voltage drops, and statistics show that more than 60% of voltage drops are related to severe weather (such as lightning strikes, storms); system failures, especially system single-phase-to-ground faults, are another cause of voltage drops The important reason is that when the transmission line of the power system fails, the power users on the line even hundreds of meters away w...
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IPC IPC(8): G01R19/25
Inventor 仲兴荣刘家胜陈蕾
Owner SUZHOU UNIV