Method for over-speed protection of turbine under load shedding working condition

Abstract

The invention discloses a method for over-speed protection of a turbine under the load shedding working condition, which comprises the following steps that: (1) when the load of a unit is more than or equal to 30 percent of rated load and a generator oil switch is switched off, over-speed protection control (OPC) acts, and when the rotating speed of the turbine is less than the rated rotating speed, the OPC resets; and (2) when the rotating speed of the turbine is more than or equal to 103 percent of the rated rotating speed, the OPC acts, and when the rotating speed of the turbine is less than the rated rotating speed, the OPC resets. By the technical scheme, for a turbo generator unit with a fully opened intermediate regulating valve under the load shedding working condition, the OPC action frequency can be effectively reduced and secondary acceleration over-speed can be avoided under the load shedding working condition; and for a unit of which the intermediate regulating valve participates in regulating under the load shedding working condition, the rotating speed of the unit is stabilized as soon as possible. Therefore, the technical scheme has important significance for ensuring the safe and stable running of the turbo generator unit and safe power supply of a power grid.

Description

technical field [0001] The invention relates to a method for overspeed protection of a steam turbine under the condition of shedding load. Background technique [0002] The load rejection condition of the unit refers to that when the unit is connected to the power grid and operates with a certain power, suddenly due to line faults and other reasons, the protection action disconnects the main switch of the generator. When the steam power and electric power of the unit are unbalanced (actually, the electric power is zero at this time), the rotor speed of the turbogenerator suddenly soars. Under the control of hydraulic control (DEH), gradually return to the operating condition of rated speed 3000r / min. During the load shedding condition, the greatest danger comes from the dynamic speed increase of the unit. The dynamic characteristics of DEH are to effectively suppress the dynamic speed increase under the load shedding condition and return to the stable rated speed as soon as...

AI Technical Summary

Problems solved by technology

[0011] The purpose of the present invention is to provide a method for overspeed protection of a steam turbine under the load rejection condition, so as to solve the problems in the prior art that the secondary soaring speed is often high and the number of OPC actions is too high during the load rejection condition of the steam turbine unit

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