Control System of Stroke Test of Low Pressure Main Valve of Small Steam Turbine

Abstract

The invention discloses a control system for a low pressure main throttle valve stroke test of a small turbine. A low pressure main throttle valve is composed of an emergency trip protection system and an electro-hydraulic control system. The low pressure main throttle valve includes a full open stroke switch, a full closed stroke switch and a 75% stroke position stroke switch. A normally open contact of a wait-to-restore intermediate relay of a control cabinet of the emergency trip protection system is connected with a power source and a low pressure main throttle valve opening key circuit. Arestoration condition is added in control logic of the electro-hydraulic control system. The restoration condition is that a pulse signal is added when starting the test and closing the low pressuremain throttle valve, wherein logic OR operation is performed on the pulse signals and low pressure main throttle valve test in-place; if one condition is met, a low pressure main throttle valve closing command is restored and a low pressure main throttle valve opening command is sent after logic AND operation on the low pressure main throttle valve closing command after time delay disconnection. Therefore, tripping of a pump due to a fact that the 75% stroke position stroke switch cannot reflect throttle valve position signals accurately can be prevented.

Description

technical field [0001] The invention belongs to the technical field of electric power equipment in power plants, and in particular relates to a small steam turbine low-pressure main steam valve travel test control system. Background technique [0002] The low pressure main steam valve of the feed pump (feed pump turbine) is a small steam turbine isolation valve. When the small steam turbine and the pump body need to be shut down immediately when the small steam turbine and the pump body are in critical condition, the high and low pressure main valves of the feed pump are required to be closed immediately. When the feed pump is in normal operation, the adjustment of the steam intake is realized through the high and low pressure adjustment valve switches, and the high and low pressure main steam valves are in the full open state. In order to protect the safety of equipment and prevent steam turbine overspeed and bearing bush burning accidents, according to the "Twenty-five Key...

AI Technical Summary

Problems solved by technology

However, the following problems are likely to occur: the small intervals between the travel switches affect each other and cannot accurately reflect the position, the output arm of the travel switch is long and the switching difference is large; the contact position between the travel switch and the low-voltage main valve feedback transmission mechanism requires high requirements, and the small distance makes the travel switch If the distance is too large, the limit switch cannot be driven. At the same time, the vibration of the limit switch installation site will easily cause the installation position to drift

Due to the above problems, the travel switch at 75% cannot be moved in time and accurately, so that it cannot be recovered in time during the test, and the valve will be closed to cause the pump to trip.

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