Rapid AC voltage power failure detection method
A detection method and AC power supply technology, which is applied in the field of grid-connected devices of the power grid, can solve the problems of low power consumption, obvious delay effect of AC sampling circuit, and inability to accurately and timely judge AC, etc., and achieve high accuracy, good timeliness, The effect of reducing the impact
Active Publication Date: 2018-09-07
深圳市高斯宝电气技术有限公司
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Problems solved by technology
This brings a new problem to the previous detection methods of AC voltage power failure and recovery: due to the low power consumption in no-load mode, the delay effect of the X capacitor on the AC sampling circuit is obvious
[0013] Through calculation, it can be known that in the no-load state, due to the influence of the X capacitor energy storage filter, it takes more than 1 second for the AC grid port voltage to drop to the undervoltage range. The existing threshold comparison method takes more than 1 second. It takes time to determine whether the AC is powered off, which cannot meet the timeliness
For the method described in the invention application "Voltage Sag Detection Method and Device" with the publication number CN101452016A, the influence of the X capacitor is to reduce the change rate (ΔU) of the sampling voltage at the AC grid port, and the judgment condition is that ΔU must be greater than a certain value , so the patent application also cannot accurately and timely determine whether the AC is powered off
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[0033] Aiming at the current situation of poor timeliness and misjudgment in the no-load state existing in the actual application of the prior art, the present invention proposes a new detection method to make up for the drawbacks of the prior art and improve timeliness and accuracy. The specific method is as follows:
[0034] In order to ensure the accuracy of sampling, the hardware adopts impedance divider attenuation circuit and fast filter circuit; adding a fast filter circuit at the back end of impedance divider attenuation circuit can ensure timeliness and avoid the interference of other circuits on sampling. A typical voltage sampling circuit is as follows: figure 2 .
[0035] The microcontroller receives the AC voltage sampling value, detects the zero-crossing moment, and uses it as the initial phase, counts the interval time T / 2 before the adjacent zero-crossing point, and calculates the AC voltage frequency f = 1 / T and the angular frequency ω = 2πf to calculate Act...
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The invention discloses a rapid AC voltage power failure detection method. The rapid AC voltage power failure detection method comprises the following steps that voltage sampling is conducted on an ACpower supply to obtain the the maximum working voltage peak value Umax, the minimum working voltage peak value Umin and angular frequency omega of the AC power supply; then, two limiting value curves(shown in the description) of the AC power supply are obtained, two change rate limiting values curves (shown in the description) for real-time comparison are obtained through differential, difference processing is conducted on a voltage sampling value Ut1 at a current moment t1 and a voltage sampling value Ut0 at a previous moment t0 to obtain delta Ut1, wherein delta Ut1 = Ut1-Ut0, and delta t= t1-t0; when the Ut1 is smaller than the lowest voltage instantaneous value Uminsin(omega t1), AC voltage power failure is determined. The rapid AC voltage power failure detection method has good timeliness and high accuracy, and can achieve rapid response to the change of power supply state of a power grid and reduce the impact of terminal equipment caused by dynamic change of the power grid.
Description
[technical field] [0001] The invention relates to a grid-connected device for a power grid, in particular to a fast detection method for AC voltage power failure. [Background technique] [0002] With the widespread application of renewable energy such as solar photovoltaic and wind energy, the energy crisis has been effectively alleviated. There are two main ways to apply renewable energy: 1. directly supply power to terminal equipment through conversion, and 2. connect to the grid to generate power through conversion. Due to the inherent random volatility and instability of renewable energy, renewable energy such as photovoltaics and wind energy are often applied in the second way. [0003] By converting the grid-connected power generation, when the grid-connected power grid is tripped due to a fault, accident or power outage maintenance, it is necessary to detect the power outage status of the grid in time. If the grid-connected power generation system is not quickly disc...
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IPC IPC(8): G01R31/42
CPCG01R31/42
Inventor 徐立平应占标
Owner 深圳市高斯宝电气技术有限公司