Steady state calculating method of ground fault of undercurrent grounding electric power system

Abstract

The invention discloses a steady state calculating method of a ground fault of an undercurrent grounding electric power system. The steady state calculating method of a ground fault of an undercurrent grounding electric power system is characterized in that: when a ground fault occurs in the undercurrent grounding electric power system, each operation parameter has asymmetric components, and as the positive sequence and negative sequence impedance and the zero sequence impedance of part of elements are different, a node admittance equation set cannot be listed directly to calculate; and through the method, decomposition is carried out in the node admittance equation set according to the symmetrical component method, and the positive sequence, negative sequence and zero sequence components are respectively calculated, and then a equation set is formed to calculate, so that the steady state voltage of each node and the steady state current of each branch can be solved when the ground fault occurs in the undercurrent grounding electric power system. The steady state calculating method of a ground fault of an undercurrent grounding electric power system can provide quantified data support for analyzing the ground fault of the electric power system.

Description

technical field [0001] The invention relates to the technical field of power systems and automation thereof, in particular to a single-phase grounding steady-state calculation method of a small current grounding power system. Background technique [0002] Electricity is a necessity for modern people's life and work. After the electric energy is produced by the power plant, it is transmitted and distributed by the power grid and supplied to the user. At present, the power system widely adopts the three-phase AC transmission mode. 110 kV and above power grid, due to the high voltage level, generally adopts a large current grounding system, that is, when a ground fault occurs in a certain phase, the protection device is directly activated to cut off the faulty line as soon as possible. Power grids of 35 kV and below, especially 10 kV distribution grids, are mostly located in densely populated areas due to low voltage, and the probability of single-phase ground faults is great...

AI Technical Summary

Problems solved by technology

As the scale of the distribution network increases, the capacitive current also increases rapidly. When a single-phase ground fault occurs, the fault current at the ground point is large, and the arc is often unable to stop, causing fire or personal injury.

[0003] When a ground fault occurs in the distribution network, its operating parameters appear asymmetrical components, and it is difficult to effectively calculate the ground fault current

At present, single-phase ground faults are mainly studied through qualitative analysis or experimental methods, which cannot be quantitatively analyzed and have relatively large limitations. It is inconvenient to carry out theoretical research and put forward targeted control measures

There are asymmetric components in each operating parameter. Due to the difference in positive sequence, negative sequence impedance and zero sequence impedance of some components, it is impossible to directly list the node admittance equations for calculation

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