Problems of Insulation Diagnostics of Power Equipment by the Method of Partial Discharges

Abstract

Target. High information value and reliability of diagnostics of isolation by partial discharges. Methods. Simulation of PD in Multisim and calculation of electrical fields of insulation defects by finite element method in the program ComSol. Results. A strong influence of the power supply on the value of voltage surge in case of emergency has been established. The method of adjustment of this influence is proposed. It was found that the oscillatory form of the PD is mainly determined not by the parameters of the insulation defect, but by the parameters of the energy object in which this defect is observed. Method for separation of aperiodic signal of PD from oscillatory component of system transient process in PD is proposed. It is shown that in operating turbogenerators and power transformers the unambiguous connection between the phase of PD occurrence and the voltage of PD occurrence is broken. Method of determination of PD occurrence place in slot part of turbogenerators is proposed. It is shown that in order to increase the reliability of comparing PD in polymer insulation of power cables of different voltage classes and geometric dimensions, when calibrating the measuring system, it is necessary to take into account the speed of propagation of the PD pulse through the cable and the capacity of the cable length unit. The concept of a corrective coefficient for calibration has been introduced and a method for determining it has been proposed. Conclusions. Taking into account the differences in PD parameters in real objects of the electric power industry, proposed in the article, from the parameters obtained in the standard laboratory model of the PD should increase the information and reliability of the PD method, as well as make it possible to conduct a comparative analysis of the results obtained under various observation conditions.

Assessment of the Technical Condition of High-Voltage Insulators during Operation

“…As a result, an electrical signal is removed from the sensor, which is directly proportional to the magnitude of the apparent charge of PD. This signal contains PD pulses and a sinusoidal component of the mains voltage [26,27].…”

Non-Contact Methods for High-Voltage Insulation Equipment Diagnosis during Operation

“…Energies 2021, 14, x FOR PEER REVIEW 2 of 16 and even destruction of the insulating elements [9][10][11][12][13][14][15][16][17][18][19]. Therefore, it is necessary to control the occurrence of local overvoltage during the high-voltage insulation operation.…”

“…Thus, the possibility of contactless detection of sources of electric fields appears important to determine the degree of their influence on the surrounding space. Additionally, the registration of local overvoltage in transformer windings, in high-voltage insulators and cables, can indicate the presence of insulation defects, which ultimately cause damage and even destruction of the insulating elements [9][10][11][12][13][14][15][16][17][18][19]. Therefore, it is necessary to control the occurrence of local overvoltage during the high-voltage insulation operation.…”