A Measuring Method of Electric Quantity Applicable to Power Supply Fast Switching Device

Abstract

Disclosed in the invention is an electrical capacity measuring method for a quick power source switching apparatus. The power source switching apparatus is connected with eight paths of voltages including respective three-phase voltages of a bus I and a bus II, one path of voltage of an incoming line, and one path of voltage of incoming line II, six paths of current magnitudes including a-phase, a-phase, c-phase currents of the incoming line I as well as a-phase, b-phase, and c-phase currents of the incoming line II, and three paths of switching device signals including signals of normally-closed auxiliary contacts of a 1DL, a 2DL, and a 3DL. On the basis of hardware filtering and utilization of a conditioning circuit, the eight paths of sine-wave voltages are structured into square waves; and the square waves are connected to a CPLD to carry out eight-path frequency measurement; and rising edges and falling edges of the square waves carry out frequency measurement, so that a one-time frequency value can be updated at half of cycle. According to the invention, the provided electrical capacity measuring method is mainly suitable for power supply switching of industrial enterprises of petrifaction, metallurgy and coal and the like; frequencies of a bus voltage and an incoming line voltage can be measured precisely; real-time sampling and tracking are realized; and accuracy of measuring of an electrical capacity needed by power supply switching can be ensured.

Description

technical field [0001] The invention relates to a measurement method, in particular to an electrical quantity measurement method suitable for a power supply fast switching device. Background technique [0002] Medium and high-voltage substations of large and medium-sized industrial enterprises such as petrochemical, metallurgy, and coal, in order to ensure the continuous industrial production process and ensure the continuous operation of important loads without power supply, are generally equipped with two-way power supply, and adopt single-female segmented wiring (such as attached figure 1 shown). When the external power grid fails, resulting in abnormal power failure or short-term power failure, the backup power supply is switched on through the power fast switching device to ensure continuous and reliable power supply. [0003] The power fast switching device selects the best closing time of the backup power switch by measuring the electrical quantities such as the fre...

AI Technical Summary

Problems solved by technology

In this way, frequency measurement depends on accurate AD sampling, and the accuracy of AD sampling depends on accurate sampling frequency tracking. The two affect each other, resulting in inaccurate frequency measurement.

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