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MMC-HVDC DC line single-pole grounding fault protection method based on current waveform recognition

A MMC-HVDC, unipolar ground fault technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the problems of insufficient quick movement, positive and negative voltage oscillation, etc., and achieve the effect of good quick movement and low cost

Active Publication Date: 2016-03-02
SHANGHAI JIAO TONG UNIV
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Problems solved by technology

However, the defects of this technology are: 1. When a single-pole grounding fault occurs, the positive and negative pole voltages oscillate. This prior art is based on the fact that the voltage of the faulty pole is about 0 after the voltage oscillation, and the voltage of the non-faulty pole is about 2 times its initial value. Troubleshooting, lack of quick action

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  • MMC-HVDC DC line single-pole grounding fault protection method based on current waveform recognition
  • MMC-HVDC DC line single-pole grounding fault protection method based on current waveform recognition
  • MMC-HVDC DC line single-pole grounding fault protection method based on current waveform recognition

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Embodiment Construction

[0017] Through the analysis of the transient current characteristics of different types of faults, it can be seen from the comparison that the DC line current is attenuated and oscillated at a high frequency near the steady-state value when only a single-pole grounding short-circuit occurs. Theoretically, transient currents have no high-frequency components during other types of faults.

[0018] Based on this feature difference, a protection scheme based on waveform recognition is proposed, and the fault is determined by real-time detection and identification of the DC line current waveform: only when the current waveform with high frequency attenuation oscillation near the steady-state value is recognized, it is determined that the system is unipolar Ground Fault.

[0019] Such as figure 1 As shown, it is a schematic diagram of the MMC-HVDC system. This embodiment adopts the transmission line as figure 2 The shown π-type equivalent circuit is equivalent, and the MMC adopts a cons...

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Abstract

By utilizing unique high-frequency attenuation oscillation characteristic of a DC line when an MMC-HVDC DC line single-pole grounding fault occurs, through waveform recognition of a single-end current quantity and extraction of an oscillation amplitude and an oscillation period of a current transient quantity, an MMC-HVDC DC line single-pole grounding fault protection method based on current waveform recognition determines that a single-pole grounding fault occurs in a system when the oscillation amplitude and the oscillation period meet a high-frequency attenuation oscillation criteria.

Description

Technical field [0001] The invention relates to a technology in the field of power detection, in particular to an MMC (modular multilevel converter)-HVDC (high voltage direct current) DC line unipolar ground fault protection scheme based on current waveform recognition. Background technique [0002] With its obvious technical advantages, flexible DC transmission is widely used in offshore wind power generation, drilling platform power supply, remote load power supply, system interconnection, and power trading. It is used to build urban DC transmission and distribution networks and expand urban power supply capacity. The power source of the integrated power generation is connected to the power grid and has broad application prospects. Compared with two-level and three-level voltage source converters (VSC), the DC output side of the modular multilevel converter has no DC energy storage capacitors, and the DC capacitors are distributed in each sub-module. Its topology It is also di...

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Application Information

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IPC IPC(8): H02H7/26
CPCH02H7/268
Inventor 宁连营邰能灵郑晓冬张希鹏刘剑
Owner SHANGHAI JIAO TONG UNIV
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