Electric power system power factor measuring device, electric power system power factor measuring method and system

Abstract

The present invention provides an electric power system power factor measuring device, an electric power system power factor measuring method and a short circuit test system. An electric power system comprises a power supply line, a protection switch, a power transformer and a short circuit switch, and the power factor measuring device comprises a voltage transformer of which the primary side is connected with the power supply line; a voltage measuring device used for obtaining a first voltage waveform of the secondary side of the voltage transformer and a second voltage waveform of the secondary side of the power transformer simultaneously when the protection switch is located in a closed state and the short circuit switch is located in a disconnection state and used for obtaining a third voltage waveform of the secondary side of the voltage transformer when the protection switch is located in the closed state and the short circuit switch is located in the closed state; a current measuring device used for obtaining a current waveform of the secondary side of the power transformer when the protection switch is located in the closed state and the short circuit switch is located in the closed state; and a data processing device used for calculating a power factor. According to the present invention, the power factor when the electric power system is in short circuit can be measured more accurately.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a power factor measuring device, a measuring method and a test system thereof. Background technique [0002] With the increase of power load and the improvement of power quality, the safety requirements for low-voltage and high-current switchgear are getting higher and higher. Therefore, it is necessary to carry out factory inspection and type test for complete sets of switchgear such as circuit breakers and switchgear. In the low-voltage and high-current short-circuit test system, in addition to providing the test voltage and test current required by the sample test, the power factor provided by the short-circuit test system must also meet the requirements, so it is necessary to accurately measure and calculate the short-circuit test system. Power factor, that is, power factor angle. [0003] At present, the methods for calculating the power factor in the short-circuit test sys...

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Problems solved by technology

However, the current for testing low-voltage and high-current test samples will be very large, usually above 65kA (even above 120kA), that is to say, the current value of the low-voltage side (secondary side) of the transformer is very large, and the secondary side of the transformer The protective switch (low-voltage circuit breaker) cannot withstand the arc generated by such a large current during the on-off process, and it is easy to damage the low-voltage circuit breaker. Therefore, the phase angle difference method cannot simultaneously measure the voltage signal and current signal of low-voltage and high-current , making it impossible to measure the power factor of the short-circuit test system during short-circuit

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