Control loop and method for improving MFT reliability of 300MW coal-fired unit

Abstract

The invention relates to a control loop for improving MFT reliability of a 300MW coal-fired unit. The control loop for improving MFT reliability of the 300MW coal-fired unit further comprises a trip cabinet, wherein the trip cabinet is connected with a manual MFT button and a DCS power failure detection circuit, the trip cabinet is provided with an MFT signal output end, the MFT signal output endof the trip cabinet is connected with a MFT signal output end of a DCS control system in parallel. According to the control loop and method for improving MFT reliability of the 300MW coal-fired unit,the reliability of the protection system is realized, when the operation of the unit is uncontrollable, especially under the condition of DCS power loss, important equipment can be safely stopped, further expansion of accidents is avoided, not only can stable operation of the unit be ensured, under special conditions, the loss can be reduced to the minimum, but also the long-term stable operationof the power grid can be further ensured.

Description

technical field [0001] The invention belongs to the technical field of frequency modulation stability evaluation, and in particular relates to a control loop and a method for improving the MFT reliability of a 300MW coal-fired unit. Background technique [0002] Main fuel trip MFT (Mail Fuel Trip) is the core of boiler safety protection. It embodies the main design idea of ​​preventing furnace explosion, and the operation reliability of MFT system is more important. At each stage of boiler operation, as long as a certain parameter and state exceeds the allowable range for safe operation of the boiler, the system will issue a main fuel trip command and an emergency trip. Once the main fuel trip signal is formed, it will trigger an emergency shutdown. Although MFT can guarantee the safety of boiler equipment and avoid major equipment damage accidents, the emergency shutdown after MFT will inevitably stop the power generation of the unit, resulting in the instability of the pow...

AI Technical Summary

Problems solved by technology

Once the main fuel trip signal is formed, it will trigger an emergency shutdown. Although MFT can guarantee the safety of boiler equipment and avoid major equipment damage accidents, the emergency shutdown after MFT will inevitably stop the power generation of the unit, resulting in the instability of the power grid. The re-ignition start will inevitably increase the new energy consumption

Usually, the MFT action relay is operated by normally open nodes. Although the control scheme using normally open contacts reduces the possibility of misoperation, it increases the possibility of refusal to operate. For example, the MFT cannot operate normally after the DCS is powered off.

If a normally closed node is used for control, that is, after the DCS loses power, the MFT can still operate, which reduces the possibility of refusal to operate, but increases the possibility of misoperation (such as false connection or relay jitter can cause false trips )

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