Method for sampling secondary loop in power system with optimized measurement accuracy

Abstract

The invention discloses an optimized sampling method for an acquisition device of a secondary loop of a power system. A current signal of a measuring loop and a current signal of a protecting loop are synchronously introduced through a data acquisition unit; an acquired data reduction and judgment system in the acquisition unit performs analysis and selection so as to select corresponding sampling loop signals as input data of a monitoring device. The method, as a measuring plan with low cost and high precision, is capable of completely combining output results of two mutual inductors in a mode of software switching, which eliminates interferences brought by traditional hardware circuit switching, makes up for precision shortages when existing acquisition devices sample low magnitude of current, and effectively improves the measuring precision within a full range. Furthermore, the method can be widely applicable to various devices such as a line oscillograph, a main variation oscillograph, a set oscillograph, a PMU, a power quality and transmission line parameter synchronously measuring device, and to analog quantity sampling when the two or more device functions synchronously exist in a device with multiple functions.

Description

technical field [0001] The invention relates to monitoring and recording, in particular to a sampling method for optimizing the measurement accuracy of a secondary circuit of a power system. Background technique [0002] The secondary output signal of the current transformer on the primary side of the substation is divided into two types: the protection signal and the measurement signal, each of which uses its own transformer. The two have completely different output working ranges and precisions. The protection signal is characterized by relatively Wide current output range, within the output range, it can measure large currents with high accuracy, while small currents have low accuracy; the characteristic of the measurement signal is that the current output range is narrow, and within the output range, it can measure small currents with high accuracy, while large currents have low accuracy . [0003] Secondary monitoring devices in the power system, such as line wave reco...

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Problems solved by technology

[0002] The secondary output signal of the current transformer on the primary side of the substation is divided into two types: the protection signal and the measurement signal, each of which uses its own transformer. The two have completely different output working ranges and precisions. The protection signal is characterized by relatively Wide current output range, within the output range, it can measure large currents with high accuracy, while small currents have low accuracy; the characteristic of the measurement signal is that the current output range is narrow, and within the output range, it can measure small currents with high accuracy, while large currents have low accuracy

[0003] Secondary monitoring devices in the power system, such as line wave recording, main transformer wave recording, unit wave recording, PMU, power quality monitoring and transmission line parameter synchronization measurement, etc., are connected to the protection circuit of the power system. The measurement accuracy is high, and the accuracy of small current signals is low. The error of measuring small currents may easily cause problems such as inaccurate ranging and positioning of the wave recorder, insufficient accuracy of the PMU phase angle, and distortion of the parameter calculation of the parameter measurement system.

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