Steady-state power generation and power transmission phase-coordinated control method for high-head pumped storage units

Abstract

A method for steady-state power generation and phase regulation control of high-head pumped storage units is proposed. This method overcomes the problem that during steady-state power generation and phase regulation of high-head pumped storage units, the volute pressure is several times higher than the turbine chamber pressure. It optimizes the ball valve closing position and the sequence of the pressurization process, as well as the interlocking and delay settings of the reverse power protection during power generation and phase regulation. The method also addresses the issue that during the power generation and phase regulation startup of high-head pumped storage units, when the guide vanes are fully closed but the ball valves are not fully closed, the high head causes the volute pressure to be much higher than the turbine chamber pressure. This is detrimental to successful pressurization and removal of the water ring around the turbine during startup, leading to the unit absorbing a large amount of active power and causing the reverse power protection to activate and cause a shutdown.

Description

Technical Field

[0001] This invention belongs to the field of pumped storage unit control technology, and relates to a method for steady-state power generation and electrical phase-coordinated control of a high-head pumped storage unit. Background Technology

[0002] Pumped storage power stations typically perform peak shaving, frequency regulation, phase regulation, and emergency backup functions within the power system. A pumped storage power station mainly consists of an upper reservoir, a lower reservoir, and underground powerhouse equipment (including generating units and ball valves). Generally, multiple generating units are connected to the ball valves and generating units via a pressure steel pipe from the upper reservoir's inlet / outlet gates, and finally discharged into the lower reservoir through the lower reservoir's inlet / outlet. The ball valves, during normal operation, function to control water flow and act as a water-blocking device during powerhouse maintenance. They have two seals: an upstream maintenance seal and a downstream working seal. The water used to activate and deactivate both seals is generally drawn from the upstream pressure steel pipe. During normal start-up and shutdown of the generating units, only the working seal is activated or deactivated.

[0003] In recent years, some pumped storage power stations have experienced self-excited vibration caused by improper sealing of ball valves. The maximum pressure pulsation in the pressure steel pipe generated by this self-excited vibration can reach twice the static pressure upstream of the ball valve, posing a significant hazard and potentially leading to serious accidents such as pipe bursts and flooding of the power plant, severely threatening the operational safety of the power station units. To address this issue, the general accident handling methods and procedures currently used by operators of various pumped storage power stations are as follows: Handling of hydraulic self-excited oscillations of ball valves...

[0004] (1) Notify the on-site personnel to cut off the water inlet pipe of the ball valve working seal injection chamber and close the ball valve working seal water inlet valve.

[0005] (2) Notify the on-site duty personnel to open the ball valve working bypass valve and manually start the unit guide vane on-site.

[0006] (3) If circumstances permit, the host computer shall manually start the turbine of the other standby unit on the same water supply steel pipe.

[0007] (4) Notify the on-duty personnel to manually engage the ball valve for repair and sealing.

[0008] (5) Notify the standby personnel to go to the upper reservoir to urgently close the inlet and outlet gates of the upper reservoir.

[0009] In summary, after a ball valve experiences self-excited oscillation, on-site personnel need to use various manual intervention methods to eliminate the hydraulic self-excited oscillation. This method, which relies solely on human analysis, judgment, and handling, not only requires a high level of technical skill and experience from the operators, but also carries the risk of safety hazards due to inadequate or incorrect human operation. Furthermore, if a large amount of water leaks from the pressure steel pipe or ball valve during on-site manual handling, there is a significant risk to the personal safety of the personnel handling the situation. Summary of the Invention

[0010] The technical problem to be solved by this invention is to provide a method for steady-state power generation and phase regulation control of high-head pumped storage units. This method overcomes the problem that during steady-state power generation and phase regulation of high-head pumped storage units, the volute pressure is several times higher than the turbine chamber pressure. It optimizes the ball valve closing position and the sequence of the pressurization process, as well as the blocking and delay settings for reverse power protection during power generation and phase regulation in the unit's protection system. Furthermore, it addresses the issue that during the power generation and phase regulation startup of high-head pumped storage units, when the guide vanes are fully closed but the ball valves are not fully closed, the high head causes the volute pressure to be much higher than the turbine chamber pressure. This is detrimental to successful pressurization and removal of the water ring around the turbine during startup, leading to the unit absorbing a large amount of active power and causing an accidental shutdown due to the reverse power protection activation during power generation and phase regulation.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for steady-state power generation and electrical phase-coordinated control of a high-head pumped storage unit, comprising the following steps:

[0012] Step 1: The unit reaches steady state during power generation and checks whether the preconditions for power generation and power phase regulation are met. Otherwise, the process alarms and indicates that the power generation and power phase regulation conditions are not met, and the process exits.

[0013] Step 2: The unit PLC controls the active and reactive power regulation, sets the active power to 0MW, opens the upper and lower labyrinth cooling water valves, and sends the generator phase modulation start mode to the unit protection. When the generator phase modulation mode is not reached, the reverse power protection is locked.

[0014] Step 3: Determine whether the active power reduction process of the unit is within the delay range. If the active power of the unit is reduced to below the "active power reduction reference value", and the active power condition is not met if the delay range is exceeded, an alarm will be set up and a message indicating that the active power reduction has failed. The process will exit and a mechanical accident shutdown will be executed.

[0015] Step 4: After the active power drops to the "reduced active power reference value", the unit PLC sends a phase adjustment mode command to the speed controller.

[0016] Step 5: Determine whether the unit's guide vanes are fully closed within the delay range. If they are not fully closed, an alarm will be set up and a message will be displayed indicating that the guide vanes have failed to close completely. The process will then exit and a mechanical accident shutdown will be executed.

[0017] Step 6: After receiving the message that the guide vanes are fully closed, the unit PLC sends a closing command to the ball valve;

[0018] Step 7: Determine whether the ball valve opening is less than or equal to the "ball valve closing reference value" within the delay range. Otherwise, the process alarm will be triggered, indicating that the ball valve closing timeout has occurred. The process will continue to execute until the ball valve opening is less than or equal to the "ball valve closing reference value", and then proceed to the next step.

[0019] Step 8: The unit's PLC calls the air-pressurization water process;

[0020] Step nine, condition selection;

[0021] Step 10: The unit's PLC is set to the excitation reactive power condition mode, with the default reactive power set to 10Mvar; at the same time, the unit's generator phase adjustment status is sent to the monitoring system.

[0022] In steps three and four, the active power reference value is reduced to 50MW; in step seven, the ball valve reference value is closed to 30%.

[0023] In step nine, the conditions include: Condition one, the ball valve is fully closed and the ball valve working seal is engaged; Condition two, the air-pressurization and water-pressurization are successful; Condition three, the flow rate of the upper labyrinth ring is normal and the flow rate of the lower labyrinth ring is normal; Condition four, the speed controller is operating in phase adjustment mode.

[0024] In step nine, if condition one is within the delay range, the ball valve is fully closed and the ball valve working seal is engaged; otherwise, the process will exit and a mechanical accident shutdown will be executed.

[0025] In step nine, if condition two is met within the delay range, the inflation and water pressurization will be successful; otherwise, a water pressurization failure will be indicated, the process will exit, and a mechanical accident shutdown will be executed.

[0026] In step nine, if condition three indicates that the flow rate of the upper and lower labyrinth rings is normal within the delay range, otherwise, a message will be displayed indicating that the labyrinth ring water supply valve failed to open, the process will exit, and a mechanical accident shutdown will be executed.

[0027] In step nine, if condition four receives the governor phase-shifting operation mode within the delay range, otherwise the governor phase-shifting operation will fail, the process will exit, and a mechanical accident shutdown will be executed.

[0028] In step nine, if all four conditions are met, the process proceeds to the next step; the delay time for the four conditions is the longest time actually required to meet the conditions plus a certain margin.

[0029] The main beneficial effects of this invention are as follows:

[0030] Overcoming the challenges of high-head pumped storage units where the volute pressure is several times higher than the turbine chamber pressure during steady-state power generation and phase adjustment, the system optimizes the ball valve closing position and the sequence of starting the pressurized water process, as well as the blocking and delay settings for reverse power protection during power generation and phase adjustment in the unit's protection system.

[0031] This solution addresses the problem that during the phase-shifting startup of high-head pumped storage units, when the guide vanes are fully closed but the ball valves are not fully closed, the high head causes the volute pressure to be much greater than the turbine chamber pressure. This is detrimental to the successful water pressurization and removal of the water ring around the turbine during phase-shifting startup, resulting in the unit absorbing a large amount of active power and causing the reverse power protection to activate and cause an accidental shutdown. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0034] like Figure 1 A method for steady-state power generation and phase-coordinated control of a high-head pumped storage unit includes the following steps:

[0035] Step 1: The unit reaches steady state during power generation and checks whether the preconditions for power generation and power phase regulation are met. Otherwise, the process alarms and indicates that the power generation and power phase regulation conditions are not met, and the process exits.

[0036] Step 2: The unit PLC controls the active and reactive power regulation, sets the active power to 0MW, opens the upper and lower labyrinth cooling water valves, and sends the generator phase modulation start mode to the unit protection. When the generator phase modulation mode is not reached, the reverse power protection is locked.

[0037] Step 3: Determine whether the active power reduction process of the unit is within the delay range. If the active power of the unit is reduced to below the "active power reduction reference value", and the active power condition is not met if the delay range is exceeded, an alarm will be set up and a message indicating that the active power reduction has failed. The process will exit and a mechanical accident shutdown will be executed.

[0038] Step 4: After the active power drops to the "reduced active power reference value", the unit PLC sends a phase adjustment mode command to the speed controller.

[0039] Step 5: Determine whether the unit's guide vanes are fully closed within the delay range. If they are not fully closed, an alarm will be set up and a message will be displayed indicating that the guide vanes have failed to close completely. The process will then exit and a mechanical accident shutdown will be executed.

[0040] Step 6: After receiving the message that the guide vanes are fully closed, the unit PLC sends a closing command to the ball valve;

[0041] Step 7: Determine whether the ball valve opening is less than or equal to the "ball valve closing reference value" within the delay range. Otherwise, the process alarm will be triggered, indicating that the ball valve closing timeout has occurred. The process will continue to execute until the ball valve opening is less than or equal to the "ball valve closing reference value", and then proceed to the next step.

[0042] Step 8: The unit's PLC calls the air-pressurization water process;

[0043] Step nine, condition selection;

[0044] Step 10: The unit's PLC is set to the excitation reactive power condition mode, with the default reactive power set to 10Mvar; at the same time, the unit's generator phase adjustment status is sent to the monitoring system.

[0045] Example 1,

[0046] Due to the diverse operating conditions of pumped storage units and frequent process transitions between different conditions, this paper primarily addresses the process transition from steady-state power generation to phase regulation in high-head pumped storage units. This is achieved by optimizing the ball valve closing position, the sequence of pressurization startup, and the delay setting for reverse power protection during power generation phase regulation. Specifically, this addresses the issue where, during the power generation phase regulation startup of high-head pumped storage units, after the guide vanes are fully closed but the ball valves are not fully closed, the high head causes the volute pressure to be significantly higher than the impeller chamber pressure. This is detrimental to successful pressurization and the removal of water rings around the impeller during startup, leading to the unit absorbing excessive active power and triggering the reverse power protection for power generation phase regulation, resulting in a shutdown. The transition process is controlled by a local LCU, which collects and controls the status of the main and auxiliary equipment PLCs and I / O, then transmits this data to the monitoring system via fiber optic communication network and receives operator station commands, enabling remote monitoring and control.

[0047] In the preferred scheme, in steps three and four, the active power reference value is reduced to 50MW; in step seven, the ball valve reference value is closed to 30%.

[0048] In the preferred embodiment, in step nine, the conditions include: condition one, the ball valve is fully closed and the ball valve working seal is engaged; condition two, the air-pressurization and water-pressurization are successful; condition three, the flow rate of the upper labyrinth ring is normal and the flow rate of the lower labyrinth ring is normal; condition four, the speed regulator is operating in phase adjustment mode.

[0049] In the preferred embodiment, in step nine, if condition one is within the delay range and the ball valve is fully closed and the working seal of the ball valve is engaged, otherwise, a message indicating that the ball valve has failed to close completely is displayed, the process exits, and a mechanical accident shutdown is executed.

[0050] In the preferred embodiment, in step nine, if condition two is successfully performed within the delay range, the inflation and water pressurization will be successful; otherwise, a water pressurization failure will be indicated, the process will exit, and a mechanical accident shutdown will be executed.

[0051] In the preferred embodiment, in step nine, if condition three indicates that the flow rate of the upper and lower labyrinth rings is normal within the delay range, otherwise, a message is displayed indicating that the labyrinth ring water supply valve has failed to open, the process exits, and a mechanical accident shutdown is executed.

[0052] In the preferred embodiment, in step nine, if condition four receives the governor phase-shifting operation mode within the delay range, otherwise the governor phase-shifting operation fails, the process exits, and a mechanical accident shutdown is executed.

[0053] In the preferred embodiment, in step nine, if all four conditions are met, the process proceeds to the next step; the delay time for the four conditions is the longest time actually required to meet the four conditions plus a certain margin.

[0054] The above method overcomes the problem that during the steady-state power generation and phase regulation of high-head pumped storage units, the spiral casing pressure is several times higher than the turbine chamber pressure. It optimizes the ball valve closing position and the sequence of the start-up pressurization process, as well as the blocking and delay settings of the reverse power protection during power generation and phase regulation in the unit protection. It solves the problem that during the power generation and phase regulation start-up of high-head pumped storage units, when the guide vanes are fully closed but the ball valves are not fully closed, the high head causes the spiral casing pressure to be much higher than the turbine chamber pressure. This is not conducive to the successful pressurization and removal of the water ring around the turbine during the unit's phase regulation start-up, resulting in the unit absorbing a large amount of active power and causing the reverse power protection to activate and cause an accidental shutdown.

[0055] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The embodiments and features described in these embodiments can be arbitrarily combined without conflict. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for steady-state power generation and electrical phase-coordinated control of a high-head pumped storage unit, characterized by: Includes the following steps: Step 1: The unit reaches steady state of power generation and checks whether the steady state power generation and power phase regulation conditions are met. Otherwise, the process alarms and prompts that the power generation and power phase regulation conditions are not met, and the process exits. Step 2: The unit PLC controls the active and reactive power regulation, sets the active power to 0MW, opens the upper and lower labyrinth cooling water valves, and sends the generator phase modulation start mode to the unit protection. When the generator phase modulation state is not entered, the reverse power protection is locked. Step 3: Determine whether the active power of the unit has been reduced within the time delay range. If the active power has been reduced to below the active power reference value within the time delay range, and the active power condition has not been met, an alarm will be set up and a message indicating that the reduction of active power has failed. The process will then exit and a mechanical accident shutdown will be executed. Step 4: After the active power drops to the active reference value, the unit PLC sends a phase adjustment mode command to the speed controller. Step 5: Determine whether the unit's guide vanes are fully closed within the delay range. If they are not fully closed, an alarm will be set up and a message will be displayed indicating that the guide vanes have failed to close completely. The process will then exit and a mechanical accident shutdown will be executed. Step 6: After receiving the message that the guide vanes are fully closed, the unit PLC sends a closing command to the ball valve; Step 7: Determine whether the ball valve opening is less than or equal to the ball valve closing reference value within the delay range. Otherwise, the process alarm will be triggered, indicating that the ball valve closing timeout has occurred. The process will continue to execute until the ball valve opening is less than or equal to the ball valve closing reference value, and then proceed to the next step. Step 8: The unit's PLC calls the air-pressurization water process; Step nine, condition selection; Step 10: The unit PLC sends the reactive power adjustment mode to the unit excitation and sets the default reactive power to 10Mvar; at the same time, the unit PLC sends the generator phase adjustment status to the monitoring system. In step nine, the conditions include: Condition 1, the ball valve is fully closed and the ball valve working seal is engaged; Condition 2, the air-pressurization and water-pressurization are successful; Condition 3, the flow rate of the upper labyrinth ring is normal and the flow rate of the lower labyrinth ring is normal; Condition 4, the speed controller is operating in phase adjustment mode. In step nine, if all four conditions are met, the process proceeds to the next step; the delay time for the four conditions is the longest time actually required to meet the conditions plus a certain margin.

2. The method for steady-state power generation and electrical phase-control of a high-head pumped storage unit according to claim 1, characterized in that: in In steps three and four, the active power reference value is 50MW; in step seven, the ball valve closing reference value is 30%.

3. The method for steady-state power generation and electrical phase-control of a high-head pumped storage unit according to claim 1, characterized in that: in In step nine, if condition one is within the delay range, the ball valve is fully closed and the ball valve working seal is engaged; otherwise, the process will exit and a mechanical accident shutdown will be executed.

4. The method for steady-state power generation and electrical phase-control of a high-head pumped storage unit according to claim 1, characterized in that: in In step nine, if condition two is met within the delay range, the inflation and water pressurization will be successful; otherwise, a water pressurization failure message will be displayed, the process will exit, and a mechanical accident shutdown will be executed.

5. The method for steady-state power generation and electrical phase-control of a high-head pumped storage unit according to claim 1, characterized in that: in In step nine, if condition three indicates that the flow rate of the upper and lower labyrinth rings is normal within the delay range, otherwise, a message will be displayed indicating that the labyrinth ring water supply valve failed to open, the process will exit, and a mechanical accident shutdown will be executed.

6. The method for steady-state power generation and electrical phase-control of a high-head pumped storage unit according to claim 1, characterized in that: in In step nine, if condition four receives the governor phase-shifting operation mode within the delay range, otherwise the governor phase-shifting operation will fail, the process will exit, and a mechanical accident shutdown will be executed.

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