Small-scale production of devices to protect substation equipment from high-frequency overvoltage pulses will be organized at Novosibirsk State Technical University. The device developed by university scientists will extend the service life of expensive equipment by suppressing overvoltage pulses.
As explained by Valentin Loman, a member of the research group, Associate professor of the Department of Occupational Safety at NSTU-NETI, Candidate of Technical Sciences, the danger of high-frequency overvoltage pulses lies in the fact that the insulation of transformer windings and generators is very sensitive to them. Periodic exposure to such processes gradually destroys the insulation, negatively affecting the service life of the equipment. Over time, as the load on the energy facility increases, the insulation may not be able to withstand, resulting in an emergency situation.
As part of the work in this area, NSTU-NETI scientists produced industrial samples of frequency-dependent devices (FCS), the characteristics of which were confirmed by high-voltage pulse measurements simulating real conditions, said Alexander Riedel, head of the work, Associate Professor of the Department of Occupational Safety, Candidate of Technical Sciences.
"In normal operation, the coil does not make any changes to the parameters of the overhead line — the device behaves like a phase wire. When a high-frequency surge pulse occurs (its source may be switching, lightning activity, and reverse insulation overlap), the resistance to current flow increases in the chip due to the skin effect. A sharp increase in resistance combined with the inductance of a device made in the form of a coil makes it possible to reduce the amplitude and increase the pulse duration. This leads to a decrease in its steepness. The suppressed pulse no longer poses a danger to the insulation of high-voltage equipment. After the pulse has passed, the resistance of the device decreases and it behaves like an ordinary conductor," said Valentin Lohman.
Scientists at NSTU-NETI have developed a unique scheme, the use of which makes it possible to simulate high-frequency pulses with various parameters. This made it possible to create a series of high-voltage pulses with different frequencies and analyze the effect of CHMs on their parameters. The experiments performed have demonstrated the high efficiency of using a chip as a protection device against high-frequency overvoltage pulses.
In addition to overhead line substations, the development is also relevant for renewable energy sources (wind farms). They are often located in hard-to-reach and remote places (coast, highlands, etc.), which limits the possibility of their constant monitoring, control and repair work. At the same time, wind turbines are located in an open area and at high altitude, which increases the likelihood of a direct lightning strike and the occurrence of high-frequency overvoltages. The research aimed at adapting the developed protective device to wind power facilities was carried out with the support of a grant from the Russian Science Foundation, added Valentin Lohman.
Currently, NSTU-NETI has signed a license agreement with ROSSETI Tyumen JSC in order to organize small-scale production of CHZU. Work is underway to prepare for the certification of devices to confirm compliance, reliability and safety of equipment with the requirements of industry standards, corporate regulations and regulatory documentation.