Troubleshooting of DEH-IIIA Steam Turbine Pure Electrocontrol System
2021-08-10 09:05:16
When a fault occurs during the long-term operation of a DEH pure electrical control system for a steam turbine, how to deal with it in a timely and correct manner is very important for the safe and reliable operation of the entire unit. As troubleshooting and maintenance engineering technicians, before dealing with these issues, we must first determine the point of failure of the equipment, to understand the specific components of the equipment failure, the severity and the methods that must be followed in the process, and must fully recognize the complexity of the failure. And the serious consequences that may occur if you violate inspection procedures and technical requirements. Only in this way can we accurately and quickly handle equipment failures.
First, the servo system fault servo system is an important part of the DEH pure electric tune system of steam turbine. Because it directly affects the on-off state of the turbine valve, it must take a very cautious attitude towards the failure. The breakdown components and processing methods that may appear on the pure electric ESC servo system of the steam turbine will be discussed one by one.
1. VCC card failures Possible VCC card failures include: communication with the BC board is interrupted; the VCC board stops operating; the LVDT adjustment circuit is abnormal; and the integrated amplification circuit is abnormal.
After determining that the fault is on the VCC card, you should first confirm whether the fault of the VCC card can be solved through online adjustment. If it is impossible to adjust and confirm that it needs to be replaced, it must ensure the safety of the unit operation and the stability of the load, that is, prevent the valve from suddenly opening or fully closing. If you want to replace the VCC card online, follow the instructions below.
(1) When the valve controlled by the VCC card is in the fully closed position and the DEH output command is 0, the unit DEH control can be cut to the manual position, then the VCC card is unplugged, and the new VCC card type, jumper and software are confirmed The version is the same as the original VCC card. Insert a new VCC card and check that it is working properly. According to the VCC card LVDT adjustment method, set the zero, fullness, amplification and bias voltage. After confirming that the control system is working properly, the status is correct, and the tracking is good, the input is automatic. Note that during the adjustment process, it must be ensured that the unit is safe and the load is stable.
(2) When the valve controlled by the VCC card is not in the fully-closed state or the DEH output command is not 0, the full stroke test of the valve must be passed, and the DEH command is forced to gradually open the valve to 0, and then the VCC card is replaced. At the same time, input power loops may be considered, and the load remains stable during the closing of the small valve. After the command goes to 0 and the valve is fully closed, it is processed again.
2. LVDT failure LVDT is the position feedback sensor on the high and mid-adjusting doors. There are 2 on each tuning door. After the high-selection processing inside the VCC card, the control command of the tuning door is compared with the control command of the tuning door to generate the servo valve for control. instruction. When replacing the faulty LVDT online, it must be determined that the second LVDT is normal, which can ensure the safe operation of the unit, and the unit load can not cause large fluctuations in the replacement process. The repair method is as follows:
(1) Use valve test or forced instruction to 0 to fully close the valve.
(2) Secondly, cut the unit control to manual operation.
(3) After confirming that another LVDT sensor is working normally, unplug the local LVDT cable plug. Note that if one failed LVDT has its plug removed from the output of the other LVDT, the valve may suddenly open.
(4) Make a note of the current faulty LVDT housing mounting position and the relative position of the stem and housing.
(5) Remove the faulty LVDT and fix the new LVDT according to the original LVDT position.
(6) Unplug the adjusting valve electrohydraulic servo valve plug and insert the LVDT plug.
(7) By gradually adding the voltage to the servo valve, gradually open the valve and adjust the zero fullness of the LVDT through the potentiometer on the VCC card panel. Note that the opening process should be slow and should not cause large fluctuations in load.
(8) After adjustment, restore LVDT and electro-hydraulic servo valve.
(9) Check that the LVDT and VCC cards are working properly. The feedback of the door adjustment commands is normal. After confirming that there will be no impact on the load, it will be put into automatic operation and the door will be gradually opened to its original position.
Second, DPU failure DPU is the DEH-IIIA steam turbine core control of pure electrical equipment. For example, if a DEH fault occurs in the DEH during operation of the steam turbine, the unit should be maintained under stable operating conditions. Carefully analyze the cause and report it to the relevant personnel before proceeding with the appropriate treatment. If the operation cannot be maintained, the unit must be shut down.
If a single-sided DPU fault occurs and does not affect the normal control of the other side's DPU, you can still operate in the automatic state and switch to manual before replacing the hardware. If both sides of the DPU fail at the same time, the DEH control should be switched to the manual position, allowing the operator to monitor the operating parameters on other devices or instruments. At this time, you can't rush to reset or replace the DPU. You should check the cause of the fault and perform corresponding processing. If there is a serious situation such as turning off the door or dumping the load after the DPU failure occurs, it should be immediately cut to manual to maintain the load.
When replacing DPU hardware and software, the following methods should be used:
(1) Cut the DEH control to the manual position.
(2) Turn off the DPU power supply to be replaced.
(3) Take out the hardware that needs to be replaced, and insert the new hardware after comparing the new hardware with the model and jumper.
(4) Turn on the power after restoring the cable connection.
(5) After confirming that the configuration to be downloaded and the point directory are correct, download it to the DPU.
(6) Observe the main I/O signals of the two DPUs. After the tracking and control status are normal, switch to automatic.
When dealing with DPU component failures, you should also pay attention to the following issues:
(1) Before replacing the network card, it is necessary to check on the computer that the setting (address) of the new network card is the same as the original network card, and the label is attached. When each NIC in the two DPUs has a fault, the auxiliary control DPU turns off the power. Before the card is powered on, the two-machine communication cable (the 344 cable) is not connected first. After the DPU recovers, it is connected again. Otherwise, the DPU is powered on. Immediately grab the master control, there may be load rejection. Therefore, before switching back to automatic, you must check the status in both DPUs carefully.
(2) When replacing the 344 cards, check the jumpers carefully. Pay special attention to the different jumpers of the master station and slave station. The 344 connection cables of the master station and slave station cannot be interchanged.
(3) When replacing the motherboard, check the jumper settings of the different CPU main boards. If necessary, check the instructions of the main board.
Third, the power system failure 1. AC power failure DEH AC power failure occurs, first of all should immediately determine whether the external power supply system failure DEH power failure. If the system is caused by the loss of power from the external power supply, it can be closed in turn after the power supply is restored and the status of the switches is checked.
If the AC power supply inside the DEH is faulty or the cause is unknown, the power must be cut off. Check the load between the power supply phase and the neutral wire, and the insulation resistance between the ground and the ground. Check the cause before powering on.
If the UPS AC power supply system is de-energized during the DEH operation, and the cause of the power failure is not easily ascertained, the UPS backup power supply should be used to continue the operation and continue to search for the cause of power failure. If it cannot be processed in time, stop it and check it after it stops.
2. DC power failure 110VDC power failure. At present, the 200MW unit power plants are powered by the DEH to supply voltage to the OPC solenoid valve. The 110VDC power supply fault may be caused by a voltage divider resistor or a power supply detection relay, in addition to an external 220VDC line fault. If the 110VDC fault occurs, the OPC online solenoid valve will not operate, so if a 110VDC fault is detected, it must be processed online. Note that since the OPC solenoid valve is electrically charged, the OPC contacts should be prevented from being short-circuited and closed when checking and replacing faulty parts. To ensure safety, temporarily disconnect the failed OPC solenoid valve and restore it after processing.
Fourth, the protection system fault DEH protection system mainly refers to the OPC card box equipment, including OPC board, MCP speed board.
1. When the speedometer fails to operate normally, the indicator light on the MCP speed plate in each OPC card box should light, indicating that the speed is greater than 1000r/rain. If the lamp is not lit or the card is found to be faulty during the self-test, be careful not to make the OPC board send an OPC action signal before replacing it, and ensure that the corresponding >103% overspeed lamp on the OPC board does not light up. Note that replacement of two or more MCP boards cannot be reset at the same time and must be performed in sequence.
2. OPC board fault The OPC board directly controls the OPC solenoid valve. When the OPC board fails to be replaced, for the sake of safety, the OPC board should be temporarily disconnected from the OPC solenoid valve, and the operator should pay close attention to the status of the unit and be prepared to deal with possible failures. When replacing the OPC board, check whether the jumpers and chips of the two OPC boards are consistent. If possible, test the new OPC board. After the replacement is completed, restore the connection between the OPC board and the OPC solenoid valve if it is confirmed that the OPC board is working properly and the OPC action signal is not issued.
3. BC control board failures Possible BC board failures include: BC board stops working or communication with the DPU is abnormal: Communication between the BC board and other I/O cards in the station is interrupted. After confirming the failure of the BC board, the BC board can be replaced online only under the premise of ensuring the safe operation of the unit.
The specific method is as follows:
(1) Cut the unit control to manual control. If the unit is a high-profile, mid-range interlock system, remove the interlock first.
(2) Unplug the BC controller board.
(3) Insert a new BC board and check if it works properly. The model, jumper, and software version of the new BC board must be the same as the original BC board.
(4) After confirming that the control system is working properly, the condition is normal, and the tracking is good, it is automatically put into operation.
Confirm that the BC board is working properly, as follows:
(1) The BC board can be cut as the main control.
(2) When the BC board is mastered, the I/O station is normal during the self-test.
(3) Select an input quantity (such as a manual key switch) for communication test to see if the DPU is normally received.
5. When other IH-cards, terminal boards, etc. in other DEH pure ESC systems fail, the following items should be carefully checked before replacement:
(1) I/O signals on this board.
(2) Whether the configuration logic is related to the signal on the board.
(3) Internal wiring.
(4) The address and type of the card.
(5) For the sake of safety, to ensure that the replacement of the part will not affect the work of other cards or cause the accident of the crew, it can also be used to temporarily block the signal of the card or terminal board or cut off the contact of the part with the external The signal jumped during the replacement process, causing the incident.
(6) When replacing any card, the signal on the I/O card must be checked, especially the switch signal. The input and output should be forced, short circuited, etc., so that the status does not change during the replacement. At the same time, it should be taken into consideration that if the status of the unit changes and the I/O status does not change due to unsafe factors during the replacement, corresponding measures should be taken. For analog signals, it should be checked whether there will be an effect on the closed-loop circuit. If the signal is not three-out-two, special attention should be paid.
Six, fault instance 1. The reasons for the unit not being able to hang on the gate may be: the power of the gate valve is not connected; the gate signal relay is not closed; the gate pressure switch is not engaged (if the main valve is open).
Treatment method: Check the power supply, check the power circuit, restore the power supply; check the relay drive circuit, and the internal program: check whether the door is open, or turn it on.
2. The reason why the door swings may be caused by: Interference between the two sides of the LVDT: Improper adjustment of the VCC stability potentiometer: LVDT signal fluctuation: The servo valve has poor characteristics.
Treatment method: LVDT sampling values ​​on both sides should be slightly biased, otherwise it should be adjusted to replace bad LVDT; adjust the VCC card stability potentiometer; check the signal line shielding, replace the poor LVDT ~ replace the servo valve.
3. The reason why the door cannot be opened may be that OPC is not reset or the OPC card is bad (the OPC card 110 is overspeeding); the gate pressure switch is not engaged; the servo valve is bad.
Processing method: First reset, invalid Replace OPC: Check if the pressure switch is in the open state once, otherwise open it: Replace the servo valve.
4. The possible reasons for the DPU to travel unilaterally include: DPU off the network: DPU failure.
Solution: Check if the network connector is loose; replace the network card: check the CPU fan; perform a human I reset for the faulty DPU: replace the CPU board in the DPU or DPU.
5. The reason for the sudden opening of the door may be that the "on-grid" signal has disappeared. Treatment method: Check the "in-line" signal to eliminate the point of failure.
6. The possible cause of communication interruption between DEH and DCS is loose communication connector. Treatment method: Check the network connector: Restart the engineering station.
7. Conclusions This paper discusses the major faults, causes of faults and treatment methods of the DEH pure electric control system for steam turbines during operation. The failures and treatment methods discussed are all in the multiple tests of the unit commissioning and the unit operation. What has been summed up and confirmed is practical and effective. Of course, there are many problems that can be researched, analyzed, and solved in the DEH control system's fault points and processing methods. We need to gradually explore in practice to better improve and improve our maintenance methods and the operation of the DEH system. quality.
First, the servo system fault servo system is an important part of the DEH pure electric tune system of steam turbine. Because it directly affects the on-off state of the turbine valve, it must take a very cautious attitude towards the failure. The breakdown components and processing methods that may appear on the pure electric ESC servo system of the steam turbine will be discussed one by one.
1. VCC card failures Possible VCC card failures include: communication with the BC board is interrupted; the VCC board stops operating; the LVDT adjustment circuit is abnormal; and the integrated amplification circuit is abnormal.
After determining that the fault is on the VCC card, you should first confirm whether the fault of the VCC card can be solved through online adjustment. If it is impossible to adjust and confirm that it needs to be replaced, it must ensure the safety of the unit operation and the stability of the load, that is, prevent the valve from suddenly opening or fully closing. If you want to replace the VCC card online, follow the instructions below.
(1) When the valve controlled by the VCC card is in the fully closed position and the DEH output command is 0, the unit DEH control can be cut to the manual position, then the VCC card is unplugged, and the new VCC card type, jumper and software are confirmed The version is the same as the original VCC card. Insert a new VCC card and check that it is working properly. According to the VCC card LVDT adjustment method, set the zero, fullness, amplification and bias voltage. After confirming that the control system is working properly, the status is correct, and the tracking is good, the input is automatic. Note that during the adjustment process, it must be ensured that the unit is safe and the load is stable.
(2) When the valve controlled by the VCC card is not in the fully-closed state or the DEH output command is not 0, the full stroke test of the valve must be passed, and the DEH command is forced to gradually open the valve to 0, and then the VCC card is replaced. At the same time, input power loops may be considered, and the load remains stable during the closing of the small valve. After the command goes to 0 and the valve is fully closed, it is processed again.
2. LVDT failure LVDT is the position feedback sensor on the high and mid-adjusting doors. There are 2 on each tuning door. After the high-selection processing inside the VCC card, the control command of the tuning door is compared with the control command of the tuning door to generate the servo valve for control. instruction. When replacing the faulty LVDT online, it must be determined that the second LVDT is normal, which can ensure the safe operation of the unit, and the unit load can not cause large fluctuations in the replacement process. The repair method is as follows:
(1) Use valve test or forced instruction to 0 to fully close the valve.
(2) Secondly, cut the unit control to manual operation.
(3) After confirming that another LVDT sensor is working normally, unplug the local LVDT cable plug. Note that if one failed LVDT has its plug removed from the output of the other LVDT, the valve may suddenly open.
(4) Make a note of the current faulty LVDT housing mounting position and the relative position of the stem and housing.
(5) Remove the faulty LVDT and fix the new LVDT according to the original LVDT position.
(6) Unplug the adjusting valve electrohydraulic servo valve plug and insert the LVDT plug.
(7) By gradually adding the voltage to the servo valve, gradually open the valve and adjust the zero fullness of the LVDT through the potentiometer on the VCC card panel. Note that the opening process should be slow and should not cause large fluctuations in load.
(8) After adjustment, restore LVDT and electro-hydraulic servo valve.
(9) Check that the LVDT and VCC cards are working properly. The feedback of the door adjustment commands is normal. After confirming that there will be no impact on the load, it will be put into automatic operation and the door will be gradually opened to its original position.
Second, DPU failure DPU is the DEH-IIIA steam turbine core control of pure electrical equipment. For example, if a DEH fault occurs in the DEH during operation of the steam turbine, the unit should be maintained under stable operating conditions. Carefully analyze the cause and report it to the relevant personnel before proceeding with the appropriate treatment. If the operation cannot be maintained, the unit must be shut down.
If a single-sided DPU fault occurs and does not affect the normal control of the other side's DPU, you can still operate in the automatic state and switch to manual before replacing the hardware. If both sides of the DPU fail at the same time, the DEH control should be switched to the manual position, allowing the operator to monitor the operating parameters on other devices or instruments. At this time, you can't rush to reset or replace the DPU. You should check the cause of the fault and perform corresponding processing. If there is a serious situation such as turning off the door or dumping the load after the DPU failure occurs, it should be immediately cut to manual to maintain the load.
When replacing DPU hardware and software, the following methods should be used:
(1) Cut the DEH control to the manual position.
(2) Turn off the DPU power supply to be replaced.
(3) Take out the hardware that needs to be replaced, and insert the new hardware after comparing the new hardware with the model and jumper.
(4) Turn on the power after restoring the cable connection.
(5) After confirming that the configuration to be downloaded and the point directory are correct, download it to the DPU.
(6) Observe the main I/O signals of the two DPUs. After the tracking and control status are normal, switch to automatic.
When dealing with DPU component failures, you should also pay attention to the following issues:
(1) Before replacing the network card, it is necessary to check on the computer that the setting (address) of the new network card is the same as the original network card, and the label is attached. When each NIC in the two DPUs has a fault, the auxiliary control DPU turns off the power. Before the card is powered on, the two-machine communication cable (the 344 cable) is not connected first. After the DPU recovers, it is connected again. Otherwise, the DPU is powered on. Immediately grab the master control, there may be load rejection. Therefore, before switching back to automatic, you must check the status in both DPUs carefully.
(2) When replacing the 344 cards, check the jumpers carefully. Pay special attention to the different jumpers of the master station and slave station. The 344 connection cables of the master station and slave station cannot be interchanged.
(3) When replacing the motherboard, check the jumper settings of the different CPU main boards. If necessary, check the instructions of the main board.
Third, the power system failure 1. AC power failure DEH AC power failure occurs, first of all should immediately determine whether the external power supply system failure DEH power failure. If the system is caused by the loss of power from the external power supply, it can be closed in turn after the power supply is restored and the status of the switches is checked.
If the AC power supply inside the DEH is faulty or the cause is unknown, the power must be cut off. Check the load between the power supply phase and the neutral wire, and the insulation resistance between the ground and the ground. Check the cause before powering on.
If the UPS AC power supply system is de-energized during the DEH operation, and the cause of the power failure is not easily ascertained, the UPS backup power supply should be used to continue the operation and continue to search for the cause of power failure. If it cannot be processed in time, stop it and check it after it stops.
2. DC power failure 110VDC power failure. At present, the 200MW unit power plants are powered by the DEH to supply voltage to the OPC solenoid valve. The 110VDC power supply fault may be caused by a voltage divider resistor or a power supply detection relay, in addition to an external 220VDC line fault. If the 110VDC fault occurs, the OPC online solenoid valve will not operate, so if a 110VDC fault is detected, it must be processed online. Note that since the OPC solenoid valve is electrically charged, the OPC contacts should be prevented from being short-circuited and closed when checking and replacing faulty parts. To ensure safety, temporarily disconnect the failed OPC solenoid valve and restore it after processing.
Fourth, the protection system fault DEH protection system mainly refers to the OPC card box equipment, including OPC board, MCP speed board.
1. When the speedometer fails to operate normally, the indicator light on the MCP speed plate in each OPC card box should light, indicating that the speed is greater than 1000r/rain. If the lamp is not lit or the card is found to be faulty during the self-test, be careful not to make the OPC board send an OPC action signal before replacing it, and ensure that the corresponding >103% overspeed lamp on the OPC board does not light up. Note that replacement of two or more MCP boards cannot be reset at the same time and must be performed in sequence.
2. OPC board fault The OPC board directly controls the OPC solenoid valve. When the OPC board fails to be replaced, for the sake of safety, the OPC board should be temporarily disconnected from the OPC solenoid valve, and the operator should pay close attention to the status of the unit and be prepared to deal with possible failures. When replacing the OPC board, check whether the jumpers and chips of the two OPC boards are consistent. If possible, test the new OPC board. After the replacement is completed, restore the connection between the OPC board and the OPC solenoid valve if it is confirmed that the OPC board is working properly and the OPC action signal is not issued.
3. BC control board failures Possible BC board failures include: BC board stops working or communication with the DPU is abnormal: Communication between the BC board and other I/O cards in the station is interrupted. After confirming the failure of the BC board, the BC board can be replaced online only under the premise of ensuring the safe operation of the unit.
The specific method is as follows:
(1) Cut the unit control to manual control. If the unit is a high-profile, mid-range interlock system, remove the interlock first.
(2) Unplug the BC controller board.
(3) Insert a new BC board and check if it works properly. The model, jumper, and software version of the new BC board must be the same as the original BC board.
(4) After confirming that the control system is working properly, the condition is normal, and the tracking is good, it is automatically put into operation.
Confirm that the BC board is working properly, as follows:
(1) The BC board can be cut as the main control.
(2) When the BC board is mastered, the I/O station is normal during the self-test.
(3) Select an input quantity (such as a manual key switch) for communication test to see if the DPU is normally received.
5. When other IH-cards, terminal boards, etc. in other DEH pure ESC systems fail, the following items should be carefully checked before replacement:
(1) I/O signals on this board.
(2) Whether the configuration logic is related to the signal on the board.
(3) Internal wiring.
(4) The address and type of the card.
(5) For the sake of safety, to ensure that the replacement of the part will not affect the work of other cards or cause the accident of the crew, it can also be used to temporarily block the signal of the card or terminal board or cut off the contact of the part with the external The signal jumped during the replacement process, causing the incident.
(6) When replacing any card, the signal on the I/O card must be checked, especially the switch signal. The input and output should be forced, short circuited, etc., so that the status does not change during the replacement. At the same time, it should be taken into consideration that if the status of the unit changes and the I/O status does not change due to unsafe factors during the replacement, corresponding measures should be taken. For analog signals, it should be checked whether there will be an effect on the closed-loop circuit. If the signal is not three-out-two, special attention should be paid.
Six, fault instance 1. The reasons for the unit not being able to hang on the gate may be: the power of the gate valve is not connected; the gate signal relay is not closed; the gate pressure switch is not engaged (if the main valve is open).
Treatment method: Check the power supply, check the power circuit, restore the power supply; check the relay drive circuit, and the internal program: check whether the door is open, or turn it on.
2. The reason why the door swings may be caused by: Interference between the two sides of the LVDT: Improper adjustment of the VCC stability potentiometer: LVDT signal fluctuation: The servo valve has poor characteristics.
Treatment method: LVDT sampling values ​​on both sides should be slightly biased, otherwise it should be adjusted to replace bad LVDT; adjust the VCC card stability potentiometer; check the signal line shielding, replace the poor LVDT ~ replace the servo valve.
3. The reason why the door cannot be opened may be that OPC is not reset or the OPC card is bad (the OPC card 110 is overspeeding); the gate pressure switch is not engaged; the servo valve is bad.
Processing method: First reset, invalid Replace OPC: Check if the pressure switch is in the open state once, otherwise open it: Replace the servo valve.
4. The possible reasons for the DPU to travel unilaterally include: DPU off the network: DPU failure.
Solution: Check if the network connector is loose; replace the network card: check the CPU fan; perform a human I reset for the faulty DPU: replace the CPU board in the DPU or DPU.
5. The reason for the sudden opening of the door may be that the "on-grid" signal has disappeared. Treatment method: Check the "in-line" signal to eliminate the point of failure.
6. The possible cause of communication interruption between DEH and DCS is loose communication connector. Treatment method: Check the network connector: Restart the engineering station.
7. Conclusions This paper discusses the major faults, causes of faults and treatment methods of the DEH pure electric control system for steam turbines during operation. The failures and treatment methods discussed are all in the multiple tests of the unit commissioning and the unit operation. What has been summed up and confirmed is practical and effective. Of course, there are many problems that can be researched, analyzed, and solved in the DEH control system's fault points and processing methods. We need to gradually explore in practice to better improve and improve our maintenance methods and the operation of the DEH system. quality.
EPDM o-rings, or ethylene propylene o-rings, are a family of synthetic elastomers with lower cost steam and chemical resistance, particularly for applications involving solvents, acids and other mild chemicals. our company has the largest inventory network of EPDM o-rings and made on demand custom manufacturing often without tooling fees, so the EPDM o-rings you need are always available. Whether it`s for water systems, braking systems, medical, pharmaceutical, food or dairy use, you can count on us to deliver your o-rings fast and efficiently.
EPDM O-Rings EPDM O-Rings
EPDM O-Rings Summary:
Ethylene-Propylene rubbers make up a family of synthetic elastomers characterized by excellent chemical and thermal resistance. EPDM materials are most commonly used in applications involving solvents, acids, and other aggressive chemicals. EPDM has very poor compatibility with most mineral and petroleum based oils and is seldom used in those applications.
EPDM O Ring,O Ring EPDM,EPDM O Rings,EPDM Rubber O Rings
Shenyang Guide Rubber Products Co.,Ltd , https://www.guiderubber.com