EXPERIMENTAL RESEARCH OF CONTROLLING HIGH VOLTAGE TRANSFORMER WINDING CONDITION BASED ON SWITCHING IMPULSES

Abstract

The importance of the research is driven by the exceptional importance of stable work of electrical equipment complex which is used at production, transportation and processing of geo-resources. Effectiveness and reliability of such geological production is strongly depends on high voltage transformer condition. Failure of such a transformer can cause serious breakage of the whole electrical energy system and even breakdown. This, in its turn, leads to serious ecological and material losses. Fail of active transformer part, especially winding, is one of the reason of accident due to the influence of over-voltage waves and short circuit electro-dynamic forces on the winding. To prevent emergence situations with high voltage transformers and production stop losses an effective technology of winding condition control is necessary. Standard methods are ineffective for detecting winding fails at early stages of development. Among the new ones and those recommended by the international expert institutes of IEC and CIGRE are modifications of the pulse method, primarily the frequency analysis method. But, despite the recognition as the most reliable and promising, this method does not always allow revealing fails of the windings, especially in the early stages of development. Moreover, a prerequisite for the use of frequency analysis method technology requires the complete removal of voltage, the transformer spacing and the use of special monitoring equipment. At the same time, to obtain reliable diagnostic results, it is necessary to have special reference signals – normograms, which are absent practically for the whole range of power transformers. These factors reduce the common effectiveness of frequency analysis method technology. That is why, at present, the issue of research and development of technology for monitoring the state of windings under operating voltage is fully relevant. The main goal of the study is an experimental research of the principal possibility of monitoring of the transformer winding condition on the basis of switching processes in the high voltage grid. Objects of the research are the windings of real transformer in two conditions – with fault and without one. Methods: the simulation method on a real physical object. In the transformer NTMI-6 a fail of the mechanical winding shift was developed on one phase. The other two phases are in normal condition. With the help of a special circuit, the transformer was connected to the network. Using a Tektronix TDS-2012 electronic oscilloscope, the voltage on the primary winding and the response signal from the same-name secondary winding were measured. The measurements were repeated for the other two phases in the same way. Results. On a real transformer of the NTMI-6 type, the principal possibility of controlling high voltage transformer winding condition by means of switching impulses was experimentally researched. It is established that monitoring of mechanical state of windings using the switching impulses could be effectively realized. It is shown that when the transformer is turned on in the network, the operating voltage can serve as a diagnostic impulse suitable for probing the mechanical condition of the transformer windings using the low-voltage impulse method.

Keywords

• condition control
• pulsed method
• probing impulse
• winding fail
• diagnostics efficiency