Distribution transformer temperature rise test winding temperature on-line test system and method

Abstract

A system for online testing of the temperature of a distribution transformer heat run test winding, comprising a three-phase power supply (1), a parallel-connected resonant circuit (2), a direct current resistance tester (3), a distribution transformer (4), and a switch (5). The phases of the three-phase power supply (1) are all serial-connected to a capacitor and then connected to the distribution transformer (4). The direct current resistance tester (3) is parallel-connected to a step-up winding cable that needs to be tested. The parallel-connected resonant circuit (2) is electrically connected to the direct current resistance tester (3). The switch (5) is connected between an input end and an output end of the direct current resistance tester (3). A method for online testing of the temperature of the distribution transformer heat run test winding, comprising: parameters of a capacitive element and of an inductive element are determined, the system for online testing of the temperature of the distribution transformer heat run test winding is designed, an adjustable inductor is adjusted to make a circuit to be in a parallel-connected resonant state, the switch (5) is disconnected while the direct current resistance tester (3) is connected for testing and analysis. Employment of the technical solution of the present invention allows for implementation of a live test of a direct current resistance and of direct calculation of a temperature rise of the winding during a distribution transformer heat run test.

Description

technical field [0001] The invention relates to the field of power supply, in particular to an online testing system and method for a distribution transformer temperature rise test winding temperature. Background technique [0002] The temperature rise test is an important basis for assessing whether the transformer can operate reliably and safely for a long time. The test usually adopts the short-circuit method, that is, the low-voltage side of the transformer is short-circuited and the high-voltage side is pressurized. Among them, the temperature rise of the pressurized winding is generally obtained after the test is completed, under the state of disconnecting the power supply, through continuous DC resistance tests, using the extrapolation method to obtain the instantaneous resistance (thermal resistance) of the power failure, and combined with the cold resistance to calculate. [0003] In the temperature rise test, the accuracy of the measured resistance is required to ...

AI Technical Summary

Problems solved by technology

However, because the temperature of the pressurized winding is high, and the winding resistance and temperature change exponentially with time, and it takes a certain amount of time for the current to stabilize in the continuous test of DC resistance, the power-off moment obtained by the extrapolation method after the power-off measurement is used The accuracy of the resistance is difficult to be guaranteed, which in turn affects the accuracy of the calculation of the temperature rise of the winding

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