Three-phase power grid voltage short-circuit fault diagnosis method

Abstract

The invention discloses a three-phase power grid voltage short-circuit fault diagnosis method, which is characterized in that a short-circuit fault type judging unit is used for judging whether a fault belongs to a three-phase ground short-circuit fault, a two-phase fault or a single-phase ground short-circuit fault according to a phase voltage amplitude; a k value calculating unit is used for calculating a ratio between a real-time line voltage amplitude and a line voltage rated value; and a two-phase fault type diagnosis unit us used for diagnosing whether the two-phase fault belongs to the ground short circuit or the inter-phase short circuit according to the situation that whether a theoretical value of the verified line voltage amplitude is equal to a real detection value or not. By utilizing two voltage sensors, the type of the short-circuit fault can be diagnosed within a half voltage cycle of a power grid, so that the hardware cost is low, the diagnosis speed is fast, the practicability is strong, and the application value is promising in market prospect.

Description

technical field [0001] The invention belongs to the technical field of three-phase power grid control, and relates to a voltage short-circuit fault diagnosis method for a three-phase power grid. Background technique [0002] In recent years, with the increase in the installed capacity of new energy grid-connected power generation such as solar energy and wind energy year by year, the penetration rate has become higher and higher, so the stability and reliability of the three-phase power grid have been affected to a certain extent. For three-phase grid-connected inverters, when a short-circuit fault occurs, the output current of the grid-connected inverter will be too large due to the voltage drop caused by the short-circuit fault of the public grid because the power generated by the new energy is equal to the output power of the inverter instantaneously. Overcurrent protection occurs, so that the three-phase grid-connected inverter is disconnected from the grid; for the thre...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for diagnosing a voltage short-circuit fault of a three-phase power grid, which solves the problems of high hardware cost, slow diagnosis speed, and low work efficiency of the detection method when a voltage fault occurs in a three-phase power grid in the prior art

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