A control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit.

Abstract

This invention relates to a control method for the branch outlet switch in the sequential control process of hydropower plant unit shutdown, belonging to the field of generator monitoring system control technology. The control method provided by this invention, applicable to the branch outlet switch in the sequential control process of hydropower plant unit shutdown, issues commands to the corresponding unit through a monitoring operation station and monitors the unit's reactive power, guide vanes, and ball valves. A countdown is added during the monitoring process to ensure that even if a single component fails and no corresponding shutdown signal is detected, the unit's outlet switch can still reliably open upon receiving the command. This invention ensures that the unit's outlet switch receives the command and reliably opens when the guide vane position switch is normal, and also ensures that the unit's outlet switch still receives the command and reliably opens when the guide vane position switch fails.

Description

Technical Field

[0001] This invention relates to a control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit, belonging to the field of control technology for hydropower station generator unit monitoring systems. Background Technology

[0002] Currently, the country is accelerating the deployment of new energy construction and promoting the development of new energy sources. Pumped storage power stations, as a mature energy storage technology, are widely used, which places higher demands on the reliability of pumped storage units. Due to the high intensity of unit operation and the frequent start-ups and shutdowns, the aging rate of some vulnerable components, such as position switches, is greatly accelerated. The original unit shutdown control process is prone to jamming due to single component failures, such as position switch failures. In this case, the unit output has already decreased to the tripping power, but the output switch has not received a tripping command from the control process and remains in the closed position, posing a risk of tripping the upstream switch. If the upstream switch trips, it will affect the reliability of the power station operation and cause a significant loss to the grid's reserve capacity. Currently, the shutdown output switch logic configured for hydropower plant generators is generally as follows: when the power is detected to be 0, where active power is controlled by the guide vanes, and setting the active power to 0 requires the guide vanes to be fully closed, a command to the unit output switch is issued. However, during on-site operation, there were instances where the guide vane position switches were damaged. In such cases, the guide vanes were fully closed, but the full-close signal was not received, resulting in the unit's outlet switch not receiving the tripping command, which posed a risk of tripping the upstream switch. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a control method for the branch outlet switch in the shutdown sequence control process of a hydropower plant unit. This invention can ensure that the unit outlet switch can reliably open when the guide vane position switch is normal, and can also ensure that the unit outlet switch can still reliably open when the guide vane position switch fails.

[0004] To achieve the above objectives, the technical solution provided by this invention is: a control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit, which is operated according to the following steps:

[0005] (1) Hydropower plant unit shutdown command: The monitoring and operation station of the hydropower plant unit sends a unit shutdown command to the corresponding unit. After receiving the shutdown command, the unit sets the reactive power of the unit to 0, closes the guide vanes and closes the ball valve.

[0006] (2) Confirm unit shutdown: Position switches are installed at the closed positions of the guide vanes and ball valves. When the guide vanes and ball valves reach the corresponding positions, the position switches send a closing signal. The monitoring station monitors the closing signals of the guide vanes and ball valves of the corresponding unit and the unit's reactive power drops to 0. After that, the unit is confirmed to be shut down and the process of switching the sub-unit outlet switches is carried out.

[0007] (3) Overtime mechanical shutdown: After the unit executes the unit shutdown command in step (1), the countdown starts in the monitoring operation station. When the countdown ends and the confirmation unit shutdown signal in step (2) is still not received, the monitoring operation station performs a mechanical shutdown operation on the unit and performs the process of switching the sub-unit outlet.

[0008] (4) Sub-unit outlet switch: The hydropower plant unit performs the sub-unit outlet switch opening process.

[0009] The unit shutdown command in step (1) shall be executed as follows:

[0010] (a) The monitoring station issues a unit shutdown order to the unit, and the corresponding unit controls the unit after detecting the unit shutdown order issued by the monitoring station.

[0011] (b) Set the reactive power of the unit to 0. The reactive power of the unit is controlled by the excitation system. Here, the AC and DC excitation switches are used to set the reactive power of the unit to 0, and the guide vanes and ball valves are closed.

[0012] In the confirmation of unit shutdown in step (2), when the monitoring station detects that the guide vane is in full-closed position signal or detects that the unit's active power has dropped to the minimum tripping power, it can be considered that the guide vane has actually closed and the next step of operation can be carried out.

[0013] During the mechanical shutdown process in step (3), the monitoring station sets a 60-second timeout countdown while the unit power is set to 0. When the countdown ends, the mechanical shutdown process begins.

[0014] In step (3) during the timeout mechanical shutdown, the emergency stop button on the monitoring station switches the shutdown process to mechanical shutdown or electrical shutdown sub-unit outlet switch, and the corresponding main trip relay is activated through hard wiring to complete the shutdown.

[0015] As can be seen from the above technical solution, the control method for the branch outlet switch of the hydropower plant unit shutdown sequential control process provided by the present invention issues commands to the corresponding unit through the monitoring operation station, and monitors the reactive power, guide vanes and ball valves of the unit. A countdown is added during the monitoring process to ensure that even if a single component fails and no corresponding shutdown signal is detected, the unit's branch outlet switch can still receive the command and reliably open. The present invention has the following advantages compared to the prior art:

[0016] (1) Because the technical solution adopted in this invention starts a countdown in the monitoring and operation station, and if no shutdown command is received when the countdown ends, the monitoring and operation station performs a mechanical shutdown operation on the unit. Therefore, this invention improves the criterion for guide vane closure, and can avoid the situation where the unit outlet switch does not receive the tripping command when the pumped storage power station frequently switches between power generation and pumping modes and the parts are easily damaged, thereby reducing the risk of unit operation.

[0017] (2) Because the technical solution adopted in this invention adds an electrical shutdown procedure button to the monitoring and operation station, this invention facilitates emergency handling by on-duty personnel in case of an accident and can effectively prevent the accident from escalating. Attached Figure Description

[0018] Figure 1 Shutdown sequence control process flowchart for outlet switch control;

[0019] Figure 2 Logic diagram for determining when the guide vane is fully closed;

[0020] Figure 3 Monitor operator countdown chart;

[0021] Figure 4 Emergency shutdown circuit diagram for monitoring operator station;

[0022] Figure 5 Electrical or mechanical shutdown judgment logic diagram.

[0023] In the diagram: 1. Drag the blade; 2. Start the blade. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0025] A control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit, provided in the technical solution of this invention, is operated according to the following steps:

[0026] (1) Hydropower plant unit shutdown command: The monitoring and operation station of the hydropower plant unit sends a unit shutdown command to the corresponding unit. After receiving the shutdown command, the unit sets the reactive power of the unit to 0, closes the guide vanes and closes the ball valve.

[0027] In this embodiment, the unit shutdown command in step (1) is executed according to the following steps:

[0028] (a) The monitoring station issues a unit shutdown order to the unit, and the corresponding unit controls the unit after detecting the unit shutdown order issued by the monitoring station.

[0029] (b) Set the reactive power of the unit to 0. The reactive power of the unit is controlled by the excitation system. Here, the AC and DC excitation switches are used to set the reactive power of the unit to 0, and the guide vanes and ball valves are closed.

[0030] (2) Confirm unit shutdown: Position switches are installed at the closed positions of the guide vanes and ball valves. When the guide vanes and ball valves reach the corresponding positions, the position switches send a closing signal. The monitoring station monitors the closing signals of the guide vanes and ball valves of the corresponding unit and the unit's reactive power drops to 0. After that, the unit is confirmed to be shut down and the process of switching the sub-unit outlet switches is carried out.

[0031] In step (2), during the confirmation of unit shutdown, such as Figure 2 As shown, to prevent process jamming caused by damage to the guide vane position switch, when the monitoring station detects that the guide vane is in the fully closed position signal or detects that the active power of the unit has dropped to the minimum tripping power, where the active power of the unit is controlled by the guide vane, when the active power is close to 0, it can be considered that the guide vane has actually closed and the next step of operation can be carried out.

[0032] (3) Overtime mechanical shutdown: After the unit executes the unit shutdown command in step (1), the countdown starts in the monitoring operation station. When the countdown ends and the confirmation unit shutdown signal in step (2) is still not received, the monitoring operation station performs a mechanical shutdown operation on the unit and performs the process of switching the sub-unit outlet.

[0033] During the mechanical shutdown process in step (3), the monitoring station sets a 60-second timeout countdown while the unit power is set to 0. When the countdown ends, the mechanical shutdown process begins.

[0034] Step (3) During the timeout mechanical shutdown, if Figure 4 and Figure 5 As shown, the emergency stop button on the monitoring station switches the shutdown process to either mechanical or electrical shutdown via the sub-unit outlet switch. Through hard-wiring, the corresponding main trip relay activates to complete the shutdown. When the emergency stop button is pressed, the control drag knife 1 and starting knife 2 disconnect, the sub-unit outlet switch stops, the excitation system stops, the guide vanes close, and the ball valve closes.

[0035] (4) Sub-unit outlet switch: The hydropower plant unit performs the sub-unit outlet switch opening process.

[0036] In this embodiment, the monitoring process SQ85 used by the monitoring operator station is as follows: Figure 3As shown, after the startup process, a shutdown command is first sent to the unit. Upon receiving the shutdown command, the reactive power is set to zero, the ball valve is closed, the emergency stop solenoid valve is closed, the governor's pumping mode is canceled, and non-PC operating condition protection is disabled. After receiving the unit's reactive power dropping to 0 and the guide vane fully closed signal determined by the position switch, the next step continues. At this point, when both the unit's active and reactive power are zero, the sub-unit outlet switch operation is performed, with a 20-second countdown. After the timeout, it switches to electrical shutdown, placing the unit outlet switch in the open position. To address situations where the guide vane fully closed signal is not received but the unit outlet switch is actually fully closed, and the unit outlet switch does not receive the tripping command, two emergency stop methods—electrical and mechanical—are designed on the monitoring operator station. A function to switch to mechanical shutdown after a timeout is set in the control flow, the criteria for guide vane closure have been optimized, and a countdown function has been added to the monitoring interface for convenient monitoring by on-duty personnel.

Claims

1. A control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit, characterized in that... Follow these steps: (1) Hydropower plant unit shutdown command: The monitoring and operation station of the hydropower plant unit sends a unit shutdown command to the corresponding unit. After receiving the shutdown command, the unit sets the reactive power of the unit to 0, closes the guide vanes and closes the ball valve. (2) Confirm unit shutdown: Position switches are installed at the closed positions of the guide vanes and ball valves. When the guide vanes and ball valves reach the corresponding positions, the position switches send a closing signal. The monitoring station monitors the closing signals of the guide vanes and ball valves of the corresponding unit and the unit's reactive power drops to 0. After that, the unit is confirmed to be shut down and the process of switching the sub-unit outlet switches is carried out. (3) Expired mechanical shutdown: After the unit executes the unit shutdown command in step (1), the countdown starts in the monitoring operation station. When the countdown ends and the confirmation unit shutdown signal in step (2) is still not received, the monitoring operation station performs a mechanical shutdown operation on the unit and performs the process of switching the sub-unit outlet. (4) Sub-unit outlet switch: The hydropower plant unit performs the sub-unit outlet switch opening process.

2. The control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit as described in claim 1, characterized in that: The unit shutdown command in step (1) shall be executed as follows: (a) The monitoring station issues a unit shutdown order to the unit, and the corresponding unit controls the unit after detecting the unit shutdown order issued by the monitoring station. (b) Set the reactive power of the unit to 0. The reactive power of the unit is controlled by the excitation system. Here, the AC and DC excitation switches are used to set the reactive power of the unit to 0, and the guide vanes and ball valves are closed.

3. The control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit as described in claim 1, characterized in that: In step (2), when the monitoring station detects that the guide vane is fully closed or the active power of the unit has been reduced to the minimum tripping power, it can be considered that the guide vane has been actually closed and the next step can be performed.

4. The control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit as described in claim 1, characterized in that: During the mechanical shutdown process in step (3), the monitoring station sets a 60-second timeout countdown while the unit power is set to 0. When the countdown ends, the mechanical shutdown process begins.

5. The control method for the branch outlet switch of the shutdown sequence control process of a hydropower plant unit as described in claim 1, characterized in that: In step (3) during the timeout mechanical shutdown, the emergency stop button on the monitoring station switches the shutdown process to mechanical shutdown or electrical shutdown sub-unit outlet switch, and the corresponding main trip relay is activated through hard wiring to complete the shutdown.

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