The neutral point grounding method of the power grid, that is, the electrical connection between the neutral point of the distribution network and the earth, is a fundamental issue of the distribution network and involves many technical and economic issues such as reliability of power supply, over-voltage, and relay protection. At present, there are many discussions in the industry and the understanding is not the same. The grounding mode of the distribution network in each country is also different. This article mainly introduces the common grounding method and its characteristics of the neutral point of the distribution network. Based on this, the suggestions for the selection of the grounding method are given.
Grounding classification
Distribution network neutral grounding can be divided into effective grounding and non-effective grounding.
The effective earthing method includes direct earthing (direct connection between neutral point and earth), earthing via small resistance (connected by a resistor with smaller resistance value and earth connection), and earthing via reactance (inductive connection with earth with small inductance and earth resistance). 3 specific methods. Due to the large fault current in single-phase grounding, it is customarily referred to as a large current grounding method.
Non-effective grounding includes ungrounded neutral point (neutral point floating to the ground or no neutral point), resonant grounding (via arc-extinguishing coil, ie inductance coil with large inductance value connected to ground), and high-resistance grounding (via Resistors with large resistance are connected to earth.) 3 specific methods. Because the current flowing through the fault point when the single-phase grounding is small, it is also called a small-current grounding method. In recent years, active grounding methods that use power electronics to implement full-component compensation such as fault current reactive power, active power, and harmonics can also be classified as non-effective grounding methods because their active current generating devices belong to flexible power distribution. (DFACTS) equipment, also known as flexible grounding.
Shenzhen Yiktun Electric Power Installation Engineering Co., Ltd. is a professional network erection, transformer installation, high and low voltage distribution system engineering, power transformer commissioning, and circuit overhaul of all kinds of high and low voltage power distribution projects below 110KV. Electricity repair and maintenance of electricity service companies.
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