Virtual grounding power transmission and distribution system

Abstract

A virtual grounding transmission and distribution system is charactered in that a virtual grounding transformer is set up in the system. Three phases of its primary side are respectively connected in the corresponding lines of the system; the three phases of the secondary side are connected in series, wherein openings are disposed between any one of those neighboring two-phase windings; the formation of the virtual grounding is by bridging impedance at both ends of the openings, or directly shorts the openings to form a triangle connection at the secondary side of the virtual grounding transformer. The invention provides a virtual grounding manner for a neutral point non-grounding system, which can quickly consume the charge stored in the capacitance relative to the grounding, thus effectively preventing the over-voltage in the restoration process of the fault phase and the sound phase to a normal grounding voltage, preventing the ferromagnetic resonant, while at the same time delaying the restoration speed of the fault voltage relative to grounding, which is propitious to not re-ignite.

Description

technical field [0001] The invention relates to a 3-35KV medium voltage power transmission and distribution system. Background technique [0002] In my country's 3-35KV medium-voltage power transmission and distribution system, the grounding method of the neutral point involves many factors such as technology, economy, and safety. The conventional grounding methods include direct grounding, non-grounding, resonance grounding, small resistance grounding, high Resistance to ground. [0003] In the 3-35KV medium voltage system, the three-wire power system with ungrounded neutral point is widely used due to its investment, operation economy and high power supply reliability; Such a cycle of extinguishing will cause the charge redistribution and accumulation of the system to the ground capacitance to generate overvoltage, which is often called "single-phase arc light grounding overvoltage", which can easily cause damage or breakdown of the internal in...

AI Technical Summary

Problems solved by technology

There is also serious interference to communication. Now the application of electronic equipment is more and more widely, and its anti-interference ability is very low. Secondary lines and equipment will cause great interference

[0006] High-resistance grounding is to improve the accuracy of line selection. It is trying to achieve safe operation of the system by adding line selection and tripping to overcome the problems of large grounding current and high overvoltage without grounding with small resistance grounding. The actual situation cannot guarantee 100% accurate line selection. , use less

However, high-impedance grounding can discharge the electromagnetic energy of resonance and single-phase grounding, and it can still maintain operation for a period of time when single-phase grounding occurs. It has high power supply reliability and safety, but there is still a high level of overvoltage. Defects, still can not adapt to the power grid with large ground capacitance current

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