Calculation And Evaluation Of Anti Short Circuit Capacity Of Large Transformer In Inner Mongolia Power Grid

The power transformer is the important device to ensure the safe and reliable operation of the power grid. In recent years, the damage by short circuit has become the leading cause of the transformer accident. To reduce the damage of the power system caused by the transformer short-circuit accident, transformer accident must be prevented and reduced. So it is imperative to check and improve the transformers’ anti-short circuit ability.In the case of short circuit, the transient process of the system occurs suddenly, short circuit current increasing, even more than dozens of times of the rated current.Short-circuit current generates heat effect, which pass the conductor in electric equipment, conductor and insulation parts may be damaged, and at the same time, under the electric shock, the transformer of the conductor can also occur deformation or damage.We analyze the failure reasons of transformer, which mainly from the increasing of short circuit impact damage caused by the increasing of short-circuit capacity, 10-35 kV arc grounding over voltage serious, the frequency of short circuit for the high load users 、the poor quality of the 10-35 kV switch, surge arrester and other products, poor anti-short circuit ability for part of the transformer, low voltage side insulation reform imperfectly from external conditions.This project calculated and evaluated the anti-short circuit ability of the internal transformer of the operating Mongolia power grid, mainly including the calculation of three-phase short-circuit current transformer. According to the three winding transformer short-circuit current calculation and simulation analysis based on the force analysis and power calculation of the actual operating conditions, the ability of anti- short circuit of transformer research analysis and the anti-short circuit ability calculation and analysis of the typical transformer, this paper put forward the influence factors of transformer anti-short circuit ability, according to the calculated safety factor of anti- short circuit of transformer the ability were grading assessment. According to the evaluation results, this paper put forward feasible suggestions and measures for the retention of the main transformer short-circuit impact damage, and provided a basis to formulate measures to effectively prevent short circuit impact and carry out targeted management. We put forward the corresponding solution that from a device anti-short circuit ability, improving the level of user equipment operation maintenance, secondary protection resection fault time, and we implement concretely at the scene, to ensure the safe and stable operation of power system.