A method and system for line selection protection of marine nuclear power platform power grid grounding fault

Abstract

The invention discloses an ocean nuclear power platform power grid grounding fault line selection protection method and an ocean nuclear power platform power grid grounding fault line selection protection system, belonging to the field of ocean nuclear power platform power grid protection. The ocean nuclear power platform power grid grounding fault line selection protection method comprises the following steps of: when a single-phase earth fault occurs in the system, if a fault current amplitude is higher than a given threshold, keeping a neutral point in a high-resistance grounding mode, selecting an optimal wavelet basis and a decomposition scale based on a maximum energy joint entropy ratio, and performing earth fault line selection by utilizing a wavelet transformation method based ona modulus maximum value; when a high-transition resistance grounding fault occurs in the system, switching the neutral point to a small-resistance grounding mode, and constructing a branch zero-sequence current and fault phase voltage break variable phase comparison line selection protection method based on features of the high-resistance grounding fault to perform grounding fault line selection.The ocean nuclear power platform power grid grounding fault line selection protection method can be effectively matched with the operation mode and the grounding fault features of an ocean nuclear power platform power system, is high in line selection accuracy rate, is suitable for various grounding fault modes possibly happening to the platform system, and effectively improves the safety defensecapacity of the ocean nuclear power platform.

Description

technical field [0001] The invention belongs to the field of marine nuclear power platform power grid protection, and more specifically relates to a method and system for protecting a ground fault line of a marine nuclear power platform power grid. Background technique [0002] The marine nuclear power platform is an offshore mobile small nuclear power plant, which is an organic combination of ship engineering and nuclear energy engineering. It can provide safe and effective energy supply for offshore oil exploitation and remote islands, and can also be used in the field of seawater desalination. The power system of the nuclear power platform is a highly integrated system of power generation, power supply inside the station, and power transmission outside the system. The system is compact in structure, and ground faults occur frequently and in complex fault forms. It is the key to quickly and accurately select and remove fault lines under various ground fault conditions tech...

AI Technical Summary

Problems solved by technology

Among them, the method based on intelligent fault line selection mainly uses information fusion technologies such as expert systems, neural networks, and fuzzy theory, and has high fault identification capabilities, but it lacks a unified standard for different ground fault forms, and the method is complicated, which leads to long line selection time. It is difficult to meet the requirements of rapid fault removal for nuclear power platform systems; methods based on fault steady-state information mainly include zero-sequence current ratio amplitude ratio method, zero-sequence active power method, harmonic method, etc. In the form of high-impedance grounding, the magnitude of the fault steady-state current is small, so the accuracy of the line selection method based on the fault steady-state information is low; The line selection method based on the amount of information is widely used in the grounding line selection protection of the distribution network system. Among them, the wavelet transform method can effectively extract the local characteristics of the fault signal, but in the actual application process, there is no adaptive wavelet transform function for the specific line fault characteristic signal. selection method

In addition, when a high transition resistance grounding fault occurs in the system, the fault characteristic quantity is still not obvious, and the sensitivity of line selection protection is low

[0005] In summary, for the power system of marine nuclear power platforms, the conventional fault line selection method has low protection sensitivity under extreme fault conditions, and it is difficult to adapt to different ground fault forms, which cannot meet the safe operation requirements of nuclear power platforms

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