High-robustness voltage sag detection method and system under extreme power grid working condition

Abstract

The invention relates to the field of electric energy quality detection of micro-grids, power distribution networks and the like, in particular to a high-robustness voltage sag detection method and system under an extreme power grid working condition. The method has good robustness, accuracy and real-time performance under the extreme power grid working condition, can achieve rapid and accurate detection of voltage sag under the severe working condition, and especially has good effects on voltage sag amplitude detection under the severe working conditions such as direct-current component interference, harmonic interference, frequency variation and three-phase imbalance faults. And moreover, the response speed is relatively high, and the voltage amplitude change can be detected in real time.

Description

technical field [0001] The invention relates to the field of power quality detection of micro-grids, distribution networks, etc., in particular to a highly robust voltage sag detection method and system under extreme power grid working conditions. Background technique [0002] As an important standard to measure the level of power supply, power quality marks the development level of a country's power industry and is directly related to the gross national product and economic benefits. With the continuous improvement of the industrial level, there are more and more precision instruments and sensitive equipment in the power grid, and the quality of power directly affects the operation of such equipment. Among all kinds of power quality problems, voltage sag is the main cause of abnormal operation of sensitive equipment, and about 70% to 90% of power quality problems are caused by voltage sag. Voltage sag has become the most serious power quality problem, and its detection and...

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Problems solved by technology

[0003] However, with the continuous development of industry, various types of single-phase, nonlinear, high-power, and impact loads are continuously connected to the power grid, and problems such as three-phase imbalance, frequency fluctuation, and harmonics are often prone to occur in the power grid.

The traditional dq transformation voltage sag detection method often includes double frequency fluctuations in the voltage amplitude calculation when the three-phase voltage is unbalanced, which is difficult to filter out and affects the accuracy of voltage sag detection; while the traditional root mean square method is easily affected by Frequency changes affect the detection accuracy, and at least half a grid cycle is required, and the real-time performance is not enough; therefore, it is difficult for traditional methods to meet the voltage amplitude and start-stop under non-ideal grid conditions such as harmonic interference, three-phase imbalance, and frequency changes. For the detection of time, it is urgent to adopt a voltage sag detection method and system suitable for harsh power grid conditions

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