CN-117108441-B - Mechanical overspeed device of hydropower station and protection control method

CN117108441BCN 117108441 BCN117108441 BCN 117108441BCN-117108441-B

Abstract

The invention provides a mechanical overspeed device of a hydropower station and a protection control method, wherein two pairs of pressure switches and a set of pressure sensors are added on a mechanical overspeed hydraulic circuit, to more accurately judge the oil pressure on the mechanical overspeed pipeline when the mechanical overspeed device acts. The LCU protection control of the unit adopts or relations between the pressure switch quantity signal and the pressure sensor analog quantity signal and is used in series with the mechanical overspeed signal node, so that the redundancy and reliability of signal judgment are improved, the probability of misoperation is reduced, and the risk of refusal operation is reduced. The water machine backup protection control uses the pressure switch and the mechanical overspeed node in series, more accurately judges the oil pressure on the mechanical overspeed pipeline when the mechanical overspeed device acts, so as to accurately judge the normal state of the system, and simultaneously, introduces the GCB brake separating signal to further avoid the risk of misoperation of the mechanical overspeed device when the machine set is in a running state, so as to solve the problems in the background art.

Inventors

ZHANG GUANXIANG
LIU HAIBO

Assignees

中国长江电力股份有限公司

Dates

Publication Date: 20260505
Application Date: 20230719

Claims (6)

1. The mechanical overspeed protection device for the hydropower station is characterized by comprising a mechanical overspeed device (3), wherein the mechanical overspeed device (3) is arranged on a main shaft (14) of the hydropower station, the mechanical overspeed device (3) is matched with a travel switch assembly, a first path of switch nodes GS1 (8) of the mechanical overspeed device and a second path of switch nodes GS2 (11) of the mechanical overspeed device are connected in parallel at a signal output end of the travel switch assembly, the signal nodes of the first path of switch nodes GS1 (8) of the mechanical overspeed device are output to a backup protection control system (12) of the hydropower station, and the signal nodes of the second path of switch nodes GS2 (11) of the mechanical overspeed device are output to a unit LCU protection control system (13); the water machine backup protection control system comprises a water machine backup protection control system (12) and a machine set LCU protection control system (13), and further comprises a GCB circuit breaker (1), wherein the GCB circuit breaker (1) is arranged at the outlet side of a generator, two paths of GCB circuit breaker opening nodes (6) are led out by the GCB circuit breaker (1), and signals of the two paths of GCB circuit breaker opening nodes (6) are respectively output to the water machine backup protection control system (12) and the machine set LCU protection control system (13); The hydraulic control system further comprises a pressure switch YLD1 (2), a pressure switch YLD2 (4) and a pressure sensor SP (5), wherein the pressure switch YLD1 (2), the pressure switch YLD2 (4) and the pressure sensor SP (5) are arranged on the mechanical overspeed hydraulic circuit, a signal node of a mechanical overspeed hydraulic circuit pressure low 1 switch action node YLD1 (7) of the pressure switch YLD1 (2) is output to a water machine backup protection control system (12), a signal node of a mechanical overspeed hydraulic circuit pressure low 2 switch action node YLD2 (9) of the pressure switch YLD2 (4) is output to a unit LCU protection control system (13), and a signal node of a mechanical overspeed hydraulic circuit pressure sensor of the pressure sensor SP (5) which is smaller than a set value node (10) is output to the unit LCU protection control system (13); Only one group of mechanical overspeed device (3) comprises flyweights (15) arranged on a main shaft (14) of the water turbine, and the flyweights (15) are matched with the travel switch assembly; The travel switch assembly comprises a protective cover (19), a travel switch (18) is arranged in the protective cover (19), the travel switch (18) is matched with a release (16) through a travel switch cam (17), and the release (16) is matched with a flyer (15); the release (16) is cut into a cylinder shape, a plane mode is adopted, and the release (16) and the travel switch cam (17) are in a point-to-point contact mode, so that the contact area is increased, and reliable contact is ensured.
2. A hydropower station mechanical overspeed protection device according to claim 1, characterized in that the protection cover (19) is a grid-hole shaped protection cover.
3. The mechanical overspeed protection apparatus of a hydropower station according to claim 1, wherein the pipelines where the pressure switch YLD1 (2), the pressure switch YLD2 (4) and the pressure sensor SP (5) are located are respectively provided with a fast pressure measuring joint, and a front meter valve is provided to facilitate the verification and replacement of the pressure switch and the pressure sensor.
4. The mechanical overspeed protection apparatus of a hydropower station according to claim 1, wherein the backup protection control system (12) of the hydropower station adopts a hard-wired control loop, and an independent control panel cabinet is arranged independently of the control of the unit LCU protection control system (13).
5. The mechanical overspeed protection device of a hydropower station according to claim 1, wherein the unit LCU protection control system (13) adopts a PLC controller automatic control mode to set an independent control panel cabinet.
6. A control method for hydropower station mechanical overspeed protection by adopting the hydropower station mechanical overspeed protection device according to any one of claims 1-5, which is characterized in that: The water machine backup protection control system (12) adopts a hard-wired control loop mode, and the water machine backup protection control logic has two types, namely: When the first path switch node GS1 (8) of the mechanical overspeed device acts, judging whether a switching node of the GCB circuit breaker (1) is in place, ensuring that the GCB circuit breaker (1) is in a switching position, wherein the switching node (6) of the GCB circuit breaker is a switching value signal, and in this way, preventing the machine set from stopping running and falling down to a fast door by mistake caused by misoperation of the mechanical overspeed device (3) when the machine set is in an running state, and avoiding the machine set shutdown condition caused by failure damage of a travel switch node of a travel switch assembly or normal close node action of a travel switch of the mechanical overspeed device caused by loosening of a bolt; In the second scheme, when the mechanical overspeed device first path switch node GS1 (8) acts, judging whether a mechanical overspeed hydraulic circuit pressure is low by 1 switch action node YLD1 (7) acts or not, and ensuring that the mechanical overspeed hydraulic circuit pressure is low by 1 switch action node YLD1 (7) acts at a setting value, wherein the mechanical overspeed hydraulic circuit pressure is low by 1 switch action node YLD1 (7) as a switching value signal, so that the situation that the mechanical overspeed device first path switch node GS1 (8) acts erroneously is avoided, and if the mechanical overspeed device travel switch node acts actually, the mechanical overspeed hydraulic circuit pressure is low by 1 switch action node YLD1 (7) is required to be used as a lock, because when the mechanical overspeed device acts, the oil pressure on the mechanical overspeed hydraulic circuit drops rapidly to 0MPa so as to ensure that the mechanical overspeed device first path switch node GS1 (8) acts actually; three control logics aiming at a unit LCU protection control system (13) are provided, and the three control logics are specifically as follows: In the first scheme, when a second path switch node GS2 (11) of the mechanical overspeed device is operated, whether the switching value of a switching operation node YLD2 (9) with the pressure of a mechanical overspeed hydraulic circuit is low or not is judged, the switching operation setting value of the switching operation node YLD2 (9) with the pressure of the mechanical overspeed hydraulic circuit is ensured, the switching operation node YLD2 (9) with the pressure of the mechanical overspeed hydraulic circuit is low is used as a switching value signal, the method is used for avoiding misoperation of the second path switch node GS2 (11) of the mechanical overspeed device, if the stroke switch node of the mechanical overspeed device is operated, the switching operation node YLD2 (9) with the pressure of the mechanical overspeed hydraulic circuit is required to be used as a blocking state, and the oil pressure on the mechanical overspeed hydraulic circuit is rapidly reduced to 0MPa when the mechanical overspeed device is operated, so that the second path switch node GS2 (11) of the mechanical overspeed device is ensured to be actually operated; In the second scheme, when a second path switch node GS2 (11) of the mechanical overspeed device acts, whether the pressure acquisition value of a pressure sensor SP (5) on the mechanical overspeed hydraulic circuit is lower than a pressure low set value SPo is judged in an analog quantity mode, the pressure value on the mechanical overspeed hydraulic circuit is more accurately judged in an analog quantity mode, so that an action dead zone of the mechanical overspeed hydraulic circuit when the pressure switch node acts is compensated, and a switching value and analog quantity mode are combined for use, so that judgment logic is more complete and reliable; in the third scheme, when the second path switch node GS2 (11) of the mechanical overspeed device acts, whether the falling edge of the grid-connected state of the unit is in place is judged, namely, when the unit is in a non-grid-connected state, the protection control logic of the unit LCU protection control system (13) can be triggered when the second path switch node GS2 (11) of the mechanical overspeed device acts, the grid-connected state of the unit is a unit LCU calculation integration point, when the grid-connected state of the unit acts, the rising edge acts, and meanwhile, the signal node is 1, when the grid-connected state of the unit disappears, namely, the falling edge acts, and meanwhile, the signal node is 0.

Description

Mechanical overspeed device of hydropower station and protection control method Technical Field The invention belongs to the field of automatic electrical control of hydropower stations, and particularly relates to a mechanical overspeed device of a hydropower station and a protection control method. Background The mechanical overspeed protection device is the most important protection for the hydropower station unit when an accident occurs. The mechanical overspeed protection device is fixed on the large shaft of the hydroelectric generating set, rotates along with the rotation of the set, is usually set as the next-stage protection of an electric rotation speed signal device, and directly controls the shutdown through a hydraulic signal when the rotation speed reaches and exceeds a factory setting action value. Meanwhile, when the unit flies, a mechanical overspeed protection device sends out a protection signal, and the signal is sent to the LCU of the unit and the backup protection control of the water machine through a travel switch node. The travel switch is arranged on the mechanical overspeed device body, the contact of the travel switch adopts a normally closed node, and the contact of the travel switch is arranged in contact with the release. The following problems exist at present: (1) The signals sent to the LCU of the unit and the backup protection control of the water machine by the travel switch node of the mechanical overspeed device belong to a single element, the control logic is imperfect, the reliability is low, and especially, the unit has the risk of misoperation in the equipment maintenance or operation process, so that the unit can be directly caused to stop in an unplanned manner. (2) The travel switch is arranged on the mechanical overspeed device body, the contact of the travel switch is a normally closed node, the cam of the contact of the travel switch is in direct stress contact with the release, the contact area is small, the travel switch node acts when the travel switch fixing bolt loosens or the travel switch cam contact loosens, and at the moment, signals of the travel switch are directly sent to the unit LCU protection control and the water machine backup protection, so that misoperation is easy to occur. (3) When the mechanical overspeed device acts, signals are directly sent to the LCU protection control of the unit and the backup protection of the water machine, the oil pressure on the mechanical overspeed pipeline is not judged, and the judgment basis is imperfect. (4) If the unit is in an operation state, unplanned shutdown of the unit can be caused if the mechanical overspeed device is in misoperation at the moment, and the processing method is simple and incomplete in logic, and because the unit cannot be in a mechanical overspeed condition in the operation state, the logic has a loophole. Disclosure of Invention The invention aims to solve the technical problem of providing a mechanical overspeed device of a hydropower station and a protection control method, wherein two pairs of pressure switches and a set of pressure sensors are added to a mechanical overspeed hydraulic circuit so as to more accurately judge the oil pressure on a mechanical overspeed pipeline when the mechanical overspeed device acts. The LCU protection control of the unit adopts or relations between the pressure switch quantity signal and the pressure sensor analog quantity signal and is used in series with the mechanical overspeed signal node, so that the redundancy and reliability of signal judgment are improved, the probability of misoperation is reduced, and the risk of refusal operation is reduced. The water machine backup protection control uses the pressure switch and the mechanical overspeed node in series, more accurately judges the oil pressure on the mechanical overspeed pipeline when the mechanical overspeed device acts, so as to accurately judge the normal state of the system, and simultaneously, introduces the GCB brake separating signal to further avoid the risk of misoperation of the mechanical overspeed device when the machine set is in a running state, so as to solve the problems in the background art. In order to realize the technical characteristics, the invention aims to realize the mechanical overspeed protection device of the hydropower station, which comprises a mechanical overspeed device, wherein the mechanical overspeed device is arranged on a main shaft of the hydropower station, the mechanical overspeed device is matched with a travel switch assembly, and a signal output end of the travel switch assembly is connected with a first path of switch node GS1 of the mechanical overspeed device and a second path of switch node GS2 of the mechanical overspeed device in parallel, wherein the signal node of the first path of switch node GS1 of the mechanical overspeed device is output to a backup protection control system of the hydropower station, and the signal node of the