Relay protection method for preventing power loss of security section of gas turbine power plant

Abstract

The invention discloses a relay protection method for preventing power loss of a security section of a gas turbine power plant. Aiming at the condition that a high-voltage plant transformer of the gasturbine power plant is a double-winding transformer, after a ground fault occurs in a plant branch, a fault branch is determined and isolated by comparing the three-phase current vector sums of the branch A and the branch B, and normal work of a fault-free branch is guaranteed. The existing protection method results in simultaneous power loss of two branches, then a security section loses a working power supply and a standby power supply, and safe operation of a generator set is affected. The relay protection method provided by the invention is simple and reliable in principle and relativelyhigh in feasibility, accords with a basic 'four-property' principle of relay protection, namely, a reliability, sensitivity, selectivity and quickness principle, is extremely low in implementation cost, can greatly improve the reliability of the security section power supply of the gas turbine power plant, and has a great application value.

Description

technical field [0001] The invention belongs to the technical field of relay protection of electric power systems, and in particular relates to a relay protection method for preventing power loss in a security section of a gas turbine power plant. Background technique [0002] Before the 1990s, the neutral point of the high-voltage factory transformer was not grounded. When the single-phase grounding, the grounding protection only acts on the signal, that is, the factory system with a voltage level of 6kV or 10kV, when the single-phase grounding current is less than At 10A, the factory system is allowed to run for 2 hours. But practice has proved that most of the single-phase grounding, especially the single-phase grounding of cables, even if the single-phase grounding current is less than 10A, it will develop into a phase-to-phase short circuit in a short time. [0003] Therefore, since the 1990s in the 20th century, most of the power systems of large generator sets have a...

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Problems solved by technology

However, because the structure of the utility power system of a gas turbine power plant is different from that of a thermal power plant, if the relay protection scheme of a conventional thermal power plant is implemented blindly, it may cause power loss in the entire plant, eventually resulting in a loss of power to the lubricating oil pump, and eventually burning power generation Serious Accident of Machine Bearing

[0006] Recently, a serious accident occurred in a gas turbine power plant in Guangdong due to a CT fault on the low voltage side of the high-voltage transformer, which led to a power failure in the whole plant, which eventually led to the burning of the generator bearing bush and huge economic losses. Plant power relay protection method to prevent the recurrence of the accident of power failure in the whole plant

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