Adaptive reclosing method for DC power grid

Abstract

The invention belongs to the field of power system relay protection and automation, and specifically relates to an adaptive reclosing method for a DC power grid. The method comprises the steps: guaranteeing the full de-ionization of a fault point after a considerable delay time period after the tripping of a fault pole circuit breaker; comparing a fault pole end voltage detection value with a single-phase grounding fault reclosing DC voltage threshold value for a single-pole grounding fault, determining that the fault disappears if the absolute value of the fault pole end voltage is greater than the single-phase grounding fault reclosing DC voltage threshold value, and carrying out the reclosing operation of a fault pole line; carrying out the sequential reclosing of circuit breakers at two ends of one pole of the fault line with a bipolar short circuit fault, i.e., firstly recovering the single-pole operation; detecting the voltage of a non-reclosing pole of a fault line after reclosing: determining that there is no physical connection point between positive and negative poles, the fault is instantaneous and is completely removed, the circuit breakers at two ends of the negative pole can be reclosed and the normal operation of the line is recovered if the voltage of the non-reclosing pole is less than a bipolar short circuit fault reclosing DC voltage threshold value.

Description

technical field [0001] The invention relates to the fields of relay protection and automation of electric power systems, in particular to an adaptive reclosing method of a symmetrical bipolar wiring structure MMC DC power grid. Background technique [0002] In recent years, my country's wind power, photovoltaic power generation and other renewable energy installed capacity has continued to expand, making the power generation center far away from the load center. The high-voltage direct current transmission method has gained great attention and development because it is suitable for long-distance and large-capacity power transmission. At present, MMC converters with active and reactive power independent control properties are widely used in flexible direct current transmission projects, and have the advantages of high output voltage level, low switching loss and good output voltage waveform. [0003] Although the use of MMC-HVDC can greatly improve the grid connection effici...

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Problems solved by technology

[0004] The present invention proposes a method for judging the nature of the fault by detecting the voltage offset. This method does not need to consider the complex dynamic characteristics of the arc, which reduces the complexity of judgment. Based on this method, a whole set of The self-adaptive reclosing scheme solves the problem of blind reclosing in the DC power grid

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