A Fault Direction Discrimination System and Discrimination Method in No-Voltage Dead Zone

Abstract

The invention discloses a voltage-dead-zone-free fault direction determining system and method. The voltage-dead-zone-free fault direction determining system comprises a fault component extracting unit, a back-side impedance calculating unit and a determining and order issuing unit, wherein the fault component extracting unit, the back-side impedance calculating unit and the determining and order issuing unit are sequentially connected. The voltage-dead-zone-free fault direction determining method includes the steps that firstly, the fault component extracting unit extracts a voltage-and-current fault component at the protection installation position; secondly, the back-side impedance calculating unit calculates through the voltage-and-current fault component to obtain protected back-side impedance used for determining the direction of a fault; finally, the direction of the fault is determined through the determining and order issuing unit, if the back-side impedance is positive, the fault is determined to be the fault in the positive direction, and if the back-side impedance is negative, the fault is determined to be the fault in the negative direction, and a locking order is issued. Testing results show that according to the fault direction determining system based on back-side impedance calculation, the direction of the fault can be accurately determined, voltage dead zones do not exist, and influences of connection of a distributed power source and a transition resistor are avoided.

Description

Technical field: [0001] The invention belongs to the field of directional protection of electric power systems, and in particular relates to a fault direction discrimination system and a discrimination method in a voltage-free dead zone. Background technique: [0002] The grid connection of new energy (including intermittent energy) brings challenges to the operation of the power system as well as the traditional power system theory, method and technical system. The short-circuit current provided by multiple types of new energy power generation devices in weakly interconnected regional power grids containing multiple types of new energy may exceed the short-circuit current provided by the system side. The impact of multiple types of new energy power generation devices. The action characteristics of relay protection based on the fault characteristics of traditional power systems will be difficult to meet the requirements. For example, in the distribution network protection s...

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Problems solved by technology

However, the direction of this short-circuit power depends on the phase relationship of the current and voltage at the protection installation. There is a voltage dead zone in the case of a three-phase short circuit, and its characteristics are affected by the transition resistance of the fault point. Maloperation may occur in the case of a two-phase short circuit of the transformer.

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