An electromagnetic voltage transformer fault analysis method and device

Abstract

The embodiment of the invention provides an electromagnetic type voltage transformer fault analysis method and device, wherein, the method comprises the following steps: after acquiring a transient process signal which saturates the transformer, collecting a neutral point grounding current of the primary winding of the transformer and a three-phase voltage of the secondary winding of the transformer; calculating the three-phase voltage and getting the zero-sequence voltage characteristic value of the transformer. After judging that the zero-sequence voltage characteristic quantity and / or the neutral point grounding current satisfy the alarm condition, the fault reason of the transformer is determined correspondingly according to the judging result. By monitoring the neutral point current and the three-phase voltage of the transformer, the zero-sequence voltage characteristic quantity and neutral point current are taken as variables to judge whether the transformer is faulty or not, Finally, according to the result of judgment, the cause of transformer fault can be determined, and the voltage and current of transformer transient process can be monitored when the transformer fault occurs, and the cause of transformer fault can be accurately analyzed based on the voltage and current obtained from the monitoring.

Description

technical field [0001] The invention relates to the field of voltage transformers, in particular to an electromagnetic voltage transformer fault analysis method and device. Background technique [0002] Electromagnetic voltage transformer (Potential transformer, PT), as a voltage conversion device, can convert a dangerous high voltage of the current system into a low voltage that can be detected by the measurement device, and is a necessary front-end device for power system protection, metering and measurement. However, due to the nonlinear characteristics of the electromagnetic transformer itself, the iron core may be saturated under the excitation of transient processes such as closing of the empty bus and fault recovery, resulting in a decrease in the inductance value and an increase in the current, causing the winding of the transformer to burn or explode. Therefore, it is necessary to conduct qualitative and quantitative analysis on the cause of the transformer failure,...

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Problems solved by technology

However, on-site measurement is often only for voltage measurement, but experience has proved that most PT faults are caused by an overcurrent burnout. Due to the nonlinearity of the transformer, the actual current value cannot be estimated from the transformer voltage

In addition, this method cannot predict the grounding fault of the system, and it is also difficult to artificially set the fault point on site to monitor the fault and the fault recovery process

In addition, the existing general-purpose overvoltage monitoring devices are often portable, and need to be dismantled after the switching test is completed, and the characteristic quantities of the transformer saturation process are scattered, and its characteristics cannot be fully reflected by a limited number of measurements

Therefore, the above two methods cannot directly respond to the cause of PT failure, resulting in repeated failures of transformers installed in some positions of the power grid, which brings hidden dangers to the production of safety locks.

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