Black start starting method of a mixed-flow medium-sized hydroelectric generator set

Abstract

A black start starting method of a mixed flow medium-sized hydroelectric generator set, relates to equipment and most mixed flow medium-sized hydroelectric generator sets with black start function, including a water turbine and auxiliary equipment thereof, a generator and auxiliary equipment thereof, a technical water supply cooling system, a speed regulator and a hydraulic system, an excitation system and the like. The black start starting process control is optimized, the manual operation steps are reduced, the starting time is saved, the safety hidden danger in the starting process is eliminated, and the black start failure risk is reduced.

Description

Technical Field

[0001] This invention belongs to the field of black start technology for hydropower units, and specifically relates to a black start method for a mixed-flow medium-sized hydropower unit. Background Technology

[0002] When a hydropower station loses all its power supply due to an accident, the hydropower generating units need to utilize the electrical energy stored in the station's DC battery system and the mechanical energy stored in the hydraulic system to start up automatically and restore power to the station. This process is called black start of the hydropower generating units. Power stations with black start units often serve as key power nodes in regional power grids. Medium-sized hydropower generating units, with their wide distribution, rapid start-up and shutdown speeds, and moderate capacity, are ideal choices for black start power sources. After a large-scale power outage due to a fault, black start units quickly start up, gradually restoring power generation to other units and ultimately restoring power to the entire regional power grid. Therefore, black start of hydropower generating units is not only a necessary measure for safe production and self-rescue after a complete power outage at the hydropower station, but also crucial for cooperating with dispatching agencies to restore the normal operation of the regional power grid.

[0003] The existing black start process for mixed-flow medium-sized hydropower units actually shares the same sequential control logic as the normal start-up process, except that the process is started separately by black start command and normal start command. When the black start conditions are met, the black start command will open the emergency oil tank valve, and pressurize the main oil tank through the emergency oil tank valve. The rest of the process is no different from the normal start-up process.

[0004] However, the shortcomings of the existing technology are that the black boot process is too complicated and involves many manual steps, resulting in a long black boot time. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a black start method for mixed-flow medium-sized hydropower units. The present invention reasonably optimizes the black start process, simplifies the start-up process to the greatest extent, reduces manual operation steps, saves start-up time, eliminates safety hazards in the start-up process, and reduces the risk of black start failure.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A black start method for a mixed-flow medium-sized hydropower unit, comprising the following steps: Step 1, Unit shutdown status: Issue black start command and check that black start conditions are met; This step has a time limit of T1. If the operation is not completed within T1, an alarm will be triggered and the process will be exited. Step 2, Cooling water operation: Open the electric valves of the technical water supply system of the unit and the main transformer. After detecting that the electric valves of the technical water supply system are fully open and the cooling water flow is normal, the unit enters the cooling water system operation state. This step has a time limit of T2. If the operation is not completed within T2, an alarm will be triggered and the process will be exited. Step 3, Hydraulic System Black Start: Issue a hydraulic system black start command to open the emergency oil tank valve; If the oil valve of the accident oil tank is detected to be closed, otherwise an alarm will be triggered and the process will exit. Step 4, Start auxiliary equipment: Remove the generator mechanical brake, stop the pit heater, start the guide bearing oil mist absorption device and carbon powder absorption device, start the main transformer cooler, and check the mechanical brake disengagement; This step has a time limit of T3. If the operation is not completed within T3, an alarm will be triggered and the process will be exited. Step 5, release the lock: disengage the speed controller locking device; This step has a time limit of T4. If the operation is not completed within T4, an alarm will be triggered and the process will be exited. Step 6, Governor Start-up: Reset the emergency stop solenoid valve, start the governor, and the unit enters idling mode; This step has a time limit of T5. If the operation is not completed within T5, an alarm will be triggered and the process will be exited. Step 7, close the demagnetizing switch: Close the demagnetizing switch; This step has a time limit of T6. If the operation is not completed within T6, an alarm will be triggered and the process will be exited. Step 8, Excitation Start-up: Put the excitation system into operation, check that the voltage of each line at the generator terminal is greater than 95% of the rated voltage and the unit speed is greater than 95% of the rated speed, and the unit enters the no-load state; This step has a time limit of T7. If the operation is not completed within T7, an alarm will be triggered and the process will be exited. Step 9, Unit grid connection: Apply synchronizing voltage, start synchronizing device, and check the closing of synchronizing point switch; This step has a time limit of T8. If the operation is not completed within T8 time, an alarm will be triggered and the process will be exited.

[0007] In step one, the conditions for a black boot include: 1) Remote water supply operation mode; 2) The DC power supply to the technical water supply control cabinet is normal; 3) The power supply to the local control cabinet is normal; 4) The unit is not in an electrical fault shutdown state; 5) The unit is not in a state of mechanical failure shutdown; 6) The unit is not in the start-up or shutdown process; 7) The speed controller operates automatically; 8) The power supply to the speed controller electrical cabinet is normal; 9) The shear pin is normal; 10) The unit is either shut down or the cooling water system is running; 11) The main transformer cooling water system is normal; 12) The excitation system is normal; 13) Electrical protection is normal; 14) The backup protection of the hydro-generator unit is normal; 15) The inlet gate is functioning normally; 16) The oil level in the guide bearing oil groove is normal; 17) The spindle sealing water is normal; 18) The gas seal is normal after inspection; 19) Mechanical braking is normal; If all 19 conditions mentioned above are met simultaneously, it means that the black start condition is met.

[0008] Preferably, T1 is 10 minutes, T2 is 1 minute and 30 seconds, T3 is 15 seconds, T4 is 15 seconds, T5 is 2 minutes, T6 is 15 seconds, T7 is 15 seconds, and T8 is 3 minutes.

[0009] Preferably, analog signals including speed, flow rate, oil level, pressure, and voltage, as well as digital signals including activation status, control mode, position, and normal faults, are all collected by the unit's local control unit and transmitted to the monitoring system server via fiber optic ring network communication. Operators can then remotely monitor and control the system from the operator station.

[0010] Preferably, before the unit is started up by black start, the black start conditions are checked and the status indicator lights are displayed normally; the feedback is sent to the operator station of the monitoring system as the basis for judging the black start conditions and status.

[0011] Preferably, during the execution of the black start process, if the device status to be detected in the current step meets the logical requirements, the process automatically proceeds to the next step.

[0012] Preferably, the equipment involved in the black-start unit includes the turbine and its auxiliary equipment, the generator and its auxiliary equipment, the governor and hydraulic system, the technical water supply and cooling system, the excitation system, and the synchronization system, covering the main and auxiliary equipment of most medium-sized turbine units. If the hydropower unit is equipped with a high-pressure oil jacking device, the high-pressure oil system is activated after starting the auxiliary equipment in step four.

[0013] The present invention can achieve the following beneficial effects: This invention optimizes the black boot process, simplifies the boot process to the greatest extent, reduces manual operation steps, saves boot time, eliminates security risks in the boot process, and reduces the risk of black boot failure. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1Flowchart of the method for booting from a black screen. Detailed Implementation

[0015] When a hydropower station loses all its power supply due to an accident, the hydropower generating units need to use the electrical energy stored in the on-site DC battery system and the mechanical energy stored in the hydraulic system to start up automatically and restore power to the station. This process is called black start of the hydropower generating units. Black start is not only a necessary measure for safe production and self-rescue after a complete power outage at a hydropower station, but also a key factor in cooperating with the dispatching agency to restore the normal operation of the regional power grid.

[0016] Therefore, in order to ensure the quality of black start, this invention proposes a black start method for mixed-flow medium-sized hydropower units, including the following steps: Step 1, Unit shutdown status: Issue black start command and check that black start conditions are met; The conditions for black boot are shown in Table 1: Table 1. Black Boot Conditions

[0017] If all 19 conditions mentioned above are met simultaneously, it means that the black start condition is met.

[0018] This step has a time limit of 10 minutes. If the operation is not completed within the time limit, an alarm will be triggered and the process will be exited. Step 2, Cooling water operation: Open the electric valves of the technical water supply system of the unit and the main transformer. After detecting that the electric valves of the technical water supply system are fully open and the cooling water flow is normal, the unit enters the cooling water system operation state. The technical water supply system is one of the dedicated auxiliary systems of a hydropower plant, and it is divided into unit technical water supply and main transformer technical water supply. This step has a time limit of 1 minute and 30 seconds. If the operation is not completed within the time limit, an alarm will be triggered and the process will be exited. Step 3, Hydraulic System Black Start: Issue a hydraulic system black start command to open the emergency oil tank valve; If the oil valve of the accident oil tank is detected to be closed, otherwise an alarm will be triggered and the process will exit. Step 4, Start auxiliary equipment: Remove the generator mechanical brake, stop the pit heater, start the guide bearing oil mist absorption device and carbon powder absorption device, start the main transformer cooler, and check the mechanical brake disengagement; This step has a time limit of 15 seconds. If the operation is not completed within the time limit, an alarm will be triggered and the process will be exited. Step 5, release the lock: disengage the speed controller locking device; This step has a time limit of 15 seconds. If the operation is not completed within the time limit, an alarm will be triggered and the process will be exited. Step 6, Governor Start-up: Reset the emergency stop solenoid valve, start the governor, and the unit enters idling mode; This step has a time limit of 2 minutes. If the operation is not completed within the time limit, an alarm will be triggered and the process will be exited. Step 7, close the demagnetizing switch: Close the demagnetizing switch; This step has a time limit of 15 seconds. If the operation is not completed within the time limit, an alarm will be triggered and the process will be exited. Step 8, Excitation Start-up: Put the excitation system into operation, check that the voltage of each line at the generator terminal is greater than 95% of the rated voltage and the unit speed is greater than 95% of the rated speed, and the unit enters the no-load state; This step has a time limit of 15 seconds. If the operation is not completed within the time limit, an alarm will be triggered and the process will be exited. Step 9, Unit grid connection: Apply synchronizing voltage, start synchronizing device, and check the closing of synchronizing point switch; This step has a time limit of 3 minutes. If the operation is not completed within the time limit, an alarm will be triggered and the process will be exited.

[0019] The startup requirements for this method include the following: 1. Analog signals such as speed, flow rate, oil level, pressure, and voltage collected by each system, as well as switch signals such as operating status, control mode, position, and normal faults, are all collected by the local control unit of the unit and sent to the monitoring system server via fiber optic ring network communication. Operators can remotely monitor and control the system from the operator station.

[0020] 2. Before starting the unit for black start, check that all start-up conditions are met and that the status indicator lights are normal; feed this information back to the operator station of the monitoring system as the basis for judging the start-up conditions and status for black start.

[0021] 3. During the black start process, when the device status to be detected in the current step meets the logical requirements, the process automatically proceeds to the next step.

[0022] 4. The equipment involved in black-start units includes the turbine and its auxiliary equipment, the generator and its auxiliary equipment, the governor and hydraulic system, the technical water supply and cooling system, the excitation system, the synchronizing system, etc., covering the main and auxiliary equipment of most medium-sized turbine units. If the hydropower unit is equipped with a high-pressure oil jacking device, the high-pressure oil system is activated after starting the auxiliary equipment in step four.

[0023] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. 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 black start method for a mixed-flow medium-sized hydropower unit, characterized in that: Step 1, Unit shutdown status: Issue black start command and check that black start conditions are met; This step has a time limit of T1. If the operation is not completed within T1, an alarm will be triggered and the process will be exited. Step 2, Cooling water operation: Open the electric valves of the technical water supply system of the unit and the main transformer. After detecting that the electric valves of the technical water supply system are fully open and the cooling water flow is normal, the unit enters the cooling water system operation state. This step has a time limit of T2. If the operation is not completed within T2, an alarm will be triggered and the process will be exited. Step 3, Hydraulic System Black Start: Issue a hydraulic system black start command to open the emergency oil tank valve; If the oil valve of the accident oil tank is detected to be closed, otherwise an alarm will be triggered and the process will exit. Step 4, Start auxiliary equipment: Remove the generator mechanical brake, stop the pit heater, start the guide bearing oil mist absorption device and carbon powder absorption device, start the main transformer cooler, and check the mechanical brake disengagement; This step has a time limit of T3. If the operation is not completed within T3, an alarm will be triggered and the process will be exited. Step 5, release the lock: disengage the speed controller locking device; This step has a time limit of T4. If the operation is not completed within T4, an alarm will be triggered and the process will be exited. Step 6, Governor Start-up: Reset the emergency stop solenoid valve, start the governor, and the unit enters idling mode; This step has a time limit of T5. If the operation is not completed within T5, an alarm will be triggered and the process will be exited. Step 7, close the demagnetizing switch: Close the demagnetizing switch; This step has a time limit of T6. If the operation is not completed within T6, an alarm will be triggered and the process will be exited. Step 8, Excitation Start-up: Put the excitation system into operation, check that the voltage of each line at the generator terminal is greater than 95% of the rated voltage and the unit speed is greater than 95% of the rated speed, and the unit enters the no-load state; This step has a time limit of T7. If the operation is not completed within T7, an alarm will be triggered and the process will be exited. Step 9, Unit grid connection: Apply synchronizing voltage, start synchronizing device, and check the closing of synchronizing point switch; This step has a time limit of T8. If the operation is not completed within T8 time, an alarm will be triggered and the process will be exited. In step one, the conditions for a black boot include: 1) Remote operation mode of the technical water supply system; 2) The DC power supply to the technical water supply control cabinet is normal; 3) The power supply to the local control cabinet is normal; 4) The unit is not in an electrical fault shutdown state; 5) The unit is not in a state of mechanical failure shutdown; 6) The unit is not in the start-up or shutdown process; 7) The speed controller operates automatically; 8) The power supply to the speed controller electrical cabinet is normal; 9) The shear pin is normal; 10) The unit is in a shutdown state or the cooling water system is in operation; 11) The main transformer cooling water system is normal; 12) The excitation system is normal; 13) Electrical protection is normal; 14) The backup protection of the hydro-generator unit is normal; 15) The inlet gate is functioning normally; 16) The oil level in the guide bearing oil groove is normal; 17) The spindle sealing water is normal; 18) The gas seal is normal after inspection; 19) Mechanical braking is normal; If all 19 conditions mentioned above are met simultaneously, it means that the black start condition is met.

2. The black start method for a mixed-flow medium-sized hydropower unit according to claim 1, characterized in that: T1 takes 10 minutes, T2 takes 1 minute and 30 seconds, T3 takes 15 seconds, T4 takes 15 seconds, T5 takes 2 minutes, T6 takes 15 seconds, T7 takes 15 seconds, and T8 takes 3 minutes.

3. The black start method for a mixed-flow medium-sized hydropower unit according to claim 1, characterized in that: Analog signals, including speed, flow rate, oil level, pressure, and voltage, as well as digital signals, including activation status, control mode, position, and normal faults, are all collected by the unit's local control unit and transmitted to the monitoring system server via fiber optic ring network communication. Operators can remotely monitor and control the system from the operator station.

4. The black start method for a mixed-flow medium-sized hydropower unit according to claim 2, characterized in that: Before starting the unit via black start, check whether the black start conditions are met and whether the status indicator lights are normal. Feedback is sent to the operator station of the monitoring system as the basis for determining the conditions and status of black boot.

5. The black start method for a mixed-flow medium-sized hydropower unit according to claim 1, characterized in that: During the black start process, if the device status to be detected in the current step meets the logical requirements, the process will automatically proceed to the next step.

6. The black start method for a mixed-flow medium-sized hydropower unit according to claim 1, characterized in that: The equipment involved in the black start unit includes the turbine and its auxiliary equipment, the generator and its auxiliary equipment, the governor and hydraulic system, the technical water supply and cooling system, the excitation system and the synchronization system. If the hydropower unit is equipped with a high-pressure oil jacking device, the high-pressure oil system is put into operation after starting the auxiliary equipment in step four.

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