Bookstore

This book is devoted to one of the main problems of modern electrical power engineering-power transformer diagnostics. The first three chapters discuss the fundamentals: The first chapter presents the physical reasons for power transformers' failures and the technical and economic consequences of disruption of the normal operation. The second chapter reviews the standard technologies for monitoring the state of the high-voltage transformers. The third chapter tells about monitoring the condition of transformer windings based on the pulse method.

The fourth chapter presents the technologies for transformer windings condition controlled by means of nanosecond pulses. The stages of improving the pulsed method based on a short probing pulse of the nanosecond range, the results of experiments on identifying the radial and axial displacements of the winding, studies of the effect of the duration and shape of the probing pulse on the sensitivity of the diagnostic procedure, and the stages of developing a mathematical as well as physical model of a power transformer are consistently presented.

Transformer Condition Control: Advanced and Traditional Technologies

Chapter 1. Failure reasons of power transformers

1.1. Analysis of failure statistics of transformer structural elements

1.2. Technical and economic consequences of disruption of the normal operation of transformers

1.3 Aging (degradation) of insulation

1.4. Violation of the integrity of transformer windings

Chapter 2 Traditional technologies for condition monitoring of high-voltage transformer

2.1 Non-electrical control methods

          2.1.1 Physical and chemical control methods

                   2.1.1.1 Chromatographic analysis of dissolved gases (GDA)

                   2.1.1.2 Physical and chemical indicators for assessing the state of                            paper insulation of power transformers in operation

          2.1.2 Vibration control

2.2 Electrical test methods

          2.2.1 Insulation monitoring using partial discharges (PD) registration

                   2.2.1.1 Methods for registering PD

                   2.2.1.2 Technical implementation of the idea of insulation diagnostics           by registering PD

          2.2.2 Measurement of no-load losses

          2.2.3 Measuring the transformation ratio

          2.2.4 Insulation resistance monitoring of transformer windings

          2.2.5 Measurement of ohm's resistance of windings

          2.2.6 Monitoring by changes in resistance (inductance) short circuit

Chapter 3 Diagnostics of the condition of transformer windings by probing pulses of microsecond duration

3.1 Physical foundations and stages of development of impulse diagnostics

3.2 Development of pulse diagnostics technology

3.3 Frequency analysis as a development of impulse diagnostics

Chapter 4 Diagnostics of the transformer winding condition by probing pulses of nanosecond duration 

4.1 Physical prerequisites for increasing the efficiency of the technology of pulse diagnostics (PD) by reducing the duration of the probe pulse.

4.2 Development of PD on physical and mathematical models of a power transformer

          4.2.1 Development a physical model of a power transformer

          4.2.2 Turn-to-turn short circuit detection

          4.2.3 Passage of the probing pulse through the windings of the physical model of the transformer

                   4.2.3.1 Passage of the probing pulse through the LV winding

                   4.2.3.2 Passage of the probing pulse through the HV winding

          4.2.4 Determining the radial and axial displacement of the winding turns

          4.2.5 Regularities of the response formation with different methods of winding connection

          4.2.6 Experimental investigation of the diagnostic capability under operating voltage

          4.2.7 Study of the influence of the probing pulse parameters on the sensitivity of the diagnostic procedure

          4.2.8 Research of power transformer PD on a mathematical model

4.3 Diagnostic complex realizing PD technology in nanosecond mode.

          4.3.1 Object characterization and experimental procedure

          4.3.2 Choice of efficiency criteria

4.4 Comparison of FRA efficiency and PD technology

          4.4.1 Diagnostics by nanosecond pulse

          4.4.2 Diagnostics by FRAX-150 device

          4.4.3 Diagnostics of a defect of the "axial displacement of turns" type in the HV winding of phase "A" by probing with nanosecond pulses

          4.4.4 Diagnostics of a defect of the "axial displacement of turns" type in the HV winding of phase "A" by the FRA method

4.5 Single-stage technology of pulse defectography.

          4.5.1. Single-step winding condition monitoring

          4.5.2. Implementation of single-stage defectography

          4.5.3 Comparison of spectra of pulses applied to an undamaged winding

4.6 Monitoring the winding condition in ON-LINE mode

Conclusion

Appendix 1 Development of a schematic diagram and a prototype of a probe pulse generator

Appendix 2 Development and approbation of programs for testing and processing of diagnostic results