A method of differential current impedance protection for power transformers

Abstract

The invention provides a differential current impedance protection method of a power transformer. The differential current impedance protection method comprises the following steps: measuring voltageand current of each side of the power transformer and forming differential current; calculating differential current impedance by applying the voltage of the side and the differential current througha power transformer protection device; forming a differential current impedance protection principle by applying differential current impedance characteristics. The differential current impedance protection principle can be used for sensitively and reliably reflecting short-circuit faults in the power transformer, especially inter-turn faults of windings; the principle can reliably ensure that incorrect actions are not caused under normal operation, external faults of the transformer and magnetizing inrush current; the method is very good for the sensitivity and reliability of protecting the power transformer. The differential current impedance protection method can be widely applied to computer type power transformer relay protection devices and provides a good technical scheme for relayprotection of the power transformer.

Description

technical field [0001] The invention relates to a power transformer differential current impedance protection method, relates to the field of power transformer protection, and is suitable for computer-type and digital power transformer relay protection devices. Background technique [0002] Transformers are important equipment for power transmission and transformation in power systems. The main protection principle of power transformers generally adopts the current differential protection principle, which is not sensitive enough to respond to inter-turn faults in transformer windings and is easily affected by inrush currents. The principle of current differential protection is to use the current on each side of the transformer to form a current differential protection. When the excitation inrush current occurs in the transformer, the state of the excitation inrush current is judged according to the typical characteristics of the excitation inrush current to ensure that the pr...

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Problems solved by technology

[0003] The invention provides a power transformer differential current impedance protection method. On the basis of the current differential protection principle, the differential current impedance is calculated by using the winding voltage and differential current, and the relevant principles and methods of impedance protection are used to form the power transformer differential current impedance. Protection method, this method solves the technical problem that the transformer differential current protection is not sensitive enough to the winding inter-turn short circuit fault and is easily affected by the excitation inrush current; more favorable

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