Uninterruptible power supply intelligent overvoltage protection device

Abstract

The invention discloses an uninterruptible power supply intelligent overvoltage protection device, and belongs to the technical field of power electronics. Overvoltage energy is absorbed by a supercapacitor C through a transformer TK and a diode D, and an auxiliary control circuit is adopted in a matched mode. The overvoltage protection device can be installed on a power supply bus and is used foreliminating lightning stroke overvoltage and internal overvoltage of a high-voltage power grid in various working conditions so as to achieve the effects of stabilizing the power grid, protecting theequipment, improving the reliability of the system and the like.

Description

technical field [0001] The invention relates to an intelligent overvoltage protection device for uninterrupted power supply, which belongs to the technical field of power electronics. It is used to eliminate lightning overvoltage and internal overvoltage of medium and high voltage power grids under various working conditions, so as to achieve the effects of stabilizing the power grid, protecting equipment, and enhancing system reliability. Background technique [0002] With the growth of the economy, the power system is also developing rapidly. The installed capacity is getting bigger and bigger, the grid voltage is getting higher and higher, and the coverage area is getting wider and wider. There are more and more large-scale impact loads and nonlinear loads in the grid. Overvoltage often occurs in the power grid, which seriously affects the safe and stable operation of the power system. Overvoltage mainly occurs in several aspects. [0003] 1. Vacuum circuit breaker open...

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Problems solved by technology

[0006] 3. The electric arc furnace is overvoltage, and the scrap steel in the electric arc furnace will often collapse and collide with the electrodes to cause a short circuit. Therefore, the current in the system will fluctuate repeatedly and irregularly, resulting in a large load impact and severe distortion of the current waveform.

Moreover, the traction power required by locomotives is increasing, and the impact and voltage fluctuations are also more serious.

And because the traction power supply system itself is a three-phase asymmetrical load, and the electric locomotive is a moving single-phase rectification belt impact load, a large amount of harmonics, negative sequence and reactive power are generated, which are injected into the power system, resulting in a decline in the power quality of the power system. In severe cases, it can lead to accidents such as relay protection device misoperation, system resonance, overvoltage damage to electrical equipment, and even large-scale power outages.

[0010] 7. Wind power grid-connected closing operation overvoltage, when the wind power grid-connected switch is connected to the grid, there will be repeated short-circuit faults on the power supply side of the main circuit breaker. Side insulation breakdown short circuit, box-type transformer under the double action of overvoltage and short-circuit current, short-circuit burning between turns of the coil, the root cause of box-type transformer failure

[0011] 8. Lightning strike overvoltage, when the lightning discharges, a strong lightning current will pass through the object on the ground, and its thermal and mechanical damage effects are very large, and it can also induce a high value of overvoltage on the adjacent lines. voltage, these excessive voltages will flow into the power supply system and cause greater harm

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