Brake control method and device suitable for hydroelectric generating set

Abstract

This invention discloses a braking control method and device applicable to hydroelectric generator sets, relating to the field of hydropower technology. The invention employs a dual verification mechanism of an LCU monitoring system and a braking cabinet. The monitoring system first determines conditions such as GCB tripping, guide vane full closure, and speed threshold, and outputs a "brake activation" signal. The braking cabinet independently collects raw source signals from the guide vane switch and GCB switch and verifies "guide vane full closure" and "GCB tripping." Braking is only activated when both conditions are met, forming a dual verification mechanism between the LCU monitoring system and the braking cabinet. This invention, through dual control logic of LCU determination and independent source signal verification by the braking cabinet, solves the problems of reliance on a single system for determination in existing technologies, which easily leads to erroneous braking activation and false alarms in status monitoring.

Description

Technical Field

[0001] This invention relates to the field of hydropower generation technology, particularly to the field of braking control technology for hydro-generator sets, and more specifically to a braking control method and device suitable for hydro-generator sets. Background Technology

[0002] In the field of hydropower, braking control of turbine generator units and pumped storage units is a core component ensuring safe shutdown of the units. The rigor of its control logic directly determines the safety and reliability of braking operations. Currently, the mainstream braking control method in the industry generally adopts the "single-link judgment-direct execution" mode: that is, the LCU monitoring system centrally collects status parameters such as "GCB position", "guide vane fully closed", and "speed signal", and after logical judgment, directly sends a braking command to the braking cabinet. The braking cabinet immediately executes the braking operation upon receiving the command.

[0003] While existing technologies have recognized the importance of braking safety and have implemented a series of improvement measures, CN113565669A proposes to monitor the GCB trip signal, guide vane full closure signal, speed measuring device fault signal, and unit speed signal in real time through a monitoring system. When all conditions are met, mechanical braking is automatically engaged. Simultaneously, dual-signal source speed measurement and redundant position switch design are used to improve reliability. CN110939542A introduces speed differential value judgment, using a triple condition of guide vane full closure, speed threshold, and speed change rate to lock braking engagement, avoiding misoperation when the guide vane is not fully closed. CN107493039A adds guide vane opening feedback and gear disc speed measuring signals collected by the governor's electronic speed controller, connecting them in series with the independent speed measuring device signal as braking conditions, and optimizing hardwiring and monitoring logic.

[0004] However, existing technologies still have key flaws:

[0005] (1) The signal verification mechanism is limited to a single system: The signal acquisition and judgment of the above schemes all rely on the LCU monitoring system or its associated speed measurement and sensing modules. The processing and verification of all status signals (such as GCB positioning and guide vane full closure) are concentrated in the same control link. For example, the dual signal source speed measurement of CN113565669A and the series connection of the speed controller ESC and independent speed measuring device of CN107493039A are not separated from the single-level verification framework dominated by the monitoring system. If the link is distorted due to sensor failure, line interference or program loopholes, it will directly lead to misjudgment of braking.

[0006] (2) Lack of independent verification capability at the braking actuator: As the final execution unit, the brake cabinet passively receives command signals from the monitoring system and lacks a mechanism for independently acquiring core status source signals such as "GCB position" and "guide vane fully closed". In the existing technology, the position switch signal of CN113565669A and the guide vane opening feedback signal of CN107493039A are both sent to the monitoring system for logical processing. The brake cabinet cannot directly obtain the original status signals and cross-verify them with the command signals. When the monitoring system issues a wrong command (such as issuing a "guide vane fully closed" signal when the guide vane is not actually fully closed), the brake cabinet cannot identify the authenticity of the signal, which will inevitably lead to erroneous braking.

[0007] (3) Risk transmission is not blocked under complex operating conditions: In scenarios such as near-ground manual braking, switching between electric braking and non-electric braking, although existing technologies improve safety through multi-parameter judgment (such as speed differential in CN110939542A and electric brake switch status in CN107493039A), they do not solve the problem of single-point failure in the "monitoring system-brake cabinet" signal link. For example, when the monitoring system misjudges "electric brake switch position closed" or "speed meets standard" due to electromagnetic interference, the brake cabinet has no secondary verification mechanism, which will cause the mechanical brake to be engaged in a state that does not meet the safety conditions, causing irreversible damage to the high-speed operating unit.

[0008] Current technological improvements focus on signal redundancy and logic optimization within the monitoring system, but fail to break through the inherent integrated "decision-execution" architecture and build a secondary verification barrier independent of the monitoring system at the braking execution end. This limitation of the technological approach means that the risk of accidental braking under complex operating conditions remains, becoming a key hidden danger restricting the safe operation of hydro-generator units. Summary of the Invention

[0009] To overcome the defects and shortcomings of the existing technology, this invention provides a braking control method and device suitable for hydro-generator sets. The purpose of this invention is to solve the problem that existing technologies rely on a single link of the LCU monitoring system for braking activation, which is prone to false activation due to signal link failures. This invention employs a dual verification mechanism of the LCU monitoring system and the braking cabinet. The monitoring system first determines conditions such as GCB occupancy, guide vane full closure, and speed threshold, and outputs a "brake activation" signal. The braking cabinet independently collects and verifies the original source signals from the guide vane switch and GCB switch, verifying conditions such as "guide vane full closure" and "GCB occupancy." Braking is only executed when both conditions are met, forming a dual verification mechanism between the LCU monitoring system and the braking cabinet. This invention, through the dual control logic of LCU determination and independent source signal verification by the braking cabinet, solves the problems of false braking activation and false alarms in status monitoring caused by relying on a single system for determination in existing technologies.

[0010] To address the problems existing in the prior art, the present invention is implemented through the following solution.

[0011] The first aspect of this invention provides a braking control method applicable to hydro-generator sets, specifically comprising:

[0012] The LCU monitoring system monitors the GCB trip signal, guide vane full closure signal, and speed signal in real time.

[0013] The PLC control module of the brake cabinet receives the "guide vane fully closed" source signal transmitted separately from the switch signal on the guide vane and the "GCB open" source signal transmitted separately from the switch signal on the GCB in real time.

[0014] Among them, the "guide vane fully closed" source signal transmitted to the PLC control module of the brake cabinet and the guide vane fully closed signal transmitted to the LCU monitoring system are independent signals; the "GCB trip" source signal transmitted to the PLC control module of the brake cabinet and the GCB trip signal transmitted to the LCU monitoring system are independent signals.

[0015] When the unit is braking, the LCU monitoring system detects that the GCB is open, the guide vanes are fully closed, and the unit speed meets the braking requirements. When the LCU monitoring system outputs a "brake engage" command to the PLC control module of the brake cabinet, the PLC control module of the brake cabinet receives the "brake engage" command and determines that it has received the "guide vanes fully closed" source signal and the "GCB open" source signal. The PLC control module then controls the unit's braking hydraulic system to perform "brake engage".

[0016] In a further preferred embodiment, when the unit is in electric braking mode during near-ground manual braking or remote automatic braking, if the unit has completed electric braking, and the LCU monitoring system determines that the unit has completed electric braking, and at the same time the LCU monitoring system determines that the unit speed is less than the first set ratio of the unit's rated speed, the PLC control module of the brake cabinet has received the "guide vane fully closed" source signal and the "GCB open" source signal, and the PLC control module controls the unit's braking hydraulic system to perform "brake activation";

[0017] If the unit does not use electric braking mode, but uses pure mechanical braking or emergency shutdown mode, after the LCU monitoring system determines that the electric brake switch is closed and the unit speed is less than the second set ratio of the unit's rated speed, the PLC control module of the brake cabinet has received the "guide vane fully closed" source signal and the "GCB open" source signal. The PLC control module controls the unit's braking hydraulic system to perform "brake activation".

[0018] More preferably, the first set percentage of the rated speed of the unit is 5%; the second set percentage of the rated speed of the unit is 20% to 30%.

[0019] In a further preferred embodiment, the LCU monitoring system receives and monitors in real time the brake engagement monitoring switch and brake release monitoring switch of the upper and lower brake discs of each brake in the brake hydraulic system. The LCU monitoring system determines the position status of the brake based on the received "engage" or "release" switch signals. When the LCU monitoring system determines that the brake is in normal condition and that the GCB is open, the guide vanes are fully closed, and the unit speed meets the braking activation requirements, it outputs a "activate braking" command to the PLC control module of the brake cabinet. When the PLC control module controls the brake hydraulic system to execute "activate braking", the brake engagement monitoring switch and brake release monitoring switch provide feedback on the "activate braking" execution status to the LCU monitoring system.

[0020] More preferably, the brake cabinet is equipped with a switching relay, and the switching signals of the brake engagement monitoring switch and the brake release monitoring switch are converted by the switching relay into passive nodes and directly transmitted to the LCU monitoring system; the brake engagement monitoring switches of the upper and lower brake discs of the brake are connected in series, and the brake being engaged when both upper and lower brake discs are engaged indicates that the brake is engaged; the brake release monitoring switches of the upper and lower brake discs of the brake are connected in series, and the brake being released when both upper and lower brake discs are released indicates that the brake is released.

[0021] In a further preferred embodiment, the LCU monitoring system receives and monitors the wear status monitoring signals of the upper and lower brake discs of each brake in the brake hydraulic system in real time. The LCU monitoring system determines the wear status of the brake based on the wear status monitoring signals. When the LCU monitoring system determines that the wear status of the brake is normal and that the GCB is open, the guide vanes are fully closed, and the unit speed meets the braking activation requirements, it outputs a "activate braking" command to the PLC control module of the brake cabinet.

[0022] In a further preferred embodiment, the wear status monitoring signal of the brake is converted into a passive node and directly transmitted to the LCU monitoring system through a relay in the brake cabinet; the wear status monitoring switches of the upper and lower brake discs are set in series, and if either the upper or lower brake disc reaches the wear alarm state, it indicates that the wear has reached the point of completion and prompts for replacement.

[0023] In a further preferred embodiment, the PLC control module controls the unit's braking hydraulic system to perform "brake activation". Specifically, the PLC control module controls the contactor on the main circuit of the oil pump motor to close, and controls the upper solenoid valve on the oil supply line between the oil tank and the brake to open, so that the oil supply line supplies oil to the brake; and controls the lower solenoid valve on the return line between the oil tank and the brake to close, so that the return line is disconnected, and braking is performed.

[0024] In a further preferred embodiment, the PLC control module receives oil temperature and level monitoring signals from the oil temperature and level monitoring sensors installed in the oil tank in real time. The PLC control module determines whether the oil temperature and level are in normal or fault condition and displays the result on the touch screen of the brake cabinet. If the condition is determined to be a low oil level and / or high oil temperature fault condition, the PLC control module processes it as a fault condition and transmits it to the LCU monitoring system.

[0025] A second aspect of the present invention provides a braking control device suitable for a hydro-generator unit, comprising an LCU monitoring system, a brake cabinet, and a brake hydraulic system. The brake cabinet is equipped with a PLC control module, and the LCU monitoring system establishes a communication connection with the PLC control module. The device also includes a guide vane fully closed monitoring sensor for acquiring the guide vane fully closed signal, a GCB trip monitoring sensor for acquiring the GCB trip signal, a speed monitoring sensor for acquiring the unit speed, a guide vane fully closed source signal monitoring sensor for acquiring the guide vane fully closed source signal, and a GCB trip source signal monitoring sensor for acquiring the GCB trip source signal. The guide vane fully closed monitoring sensor, the GCB trip monitoring sensor, and the speed monitoring sensor are connected to the LCU monitoring system, while the guide vane fully closed source signal monitoring sensor and the GCB trip source signal monitoring sensor are connected to the PLC control module.

[0026] The PLC control module receives "engage braking" or "retract braking" commands from the LCU monitoring system in real time, and controls the braking hydraulic system to perform "engage braking" or "retract braking" according to the received commands.

[0027] A further preferred embodiment includes an electric brake blade position monitoring sensor for monitoring the opening and closing of the electric brake blade, with the electric brake blade position signal connected to the LCU monitoring system.

[0028] Further preferably, it also includes a brake engagement monitoring switch and a brake release monitoring switch for monitoring the position status of the brake, and the switching signals of the brake engagement monitoring switch and the brake release monitoring switch are both connected to the LCU monitoring system; the brake engagement monitoring switch and the brake release monitoring switch are strong anti-interference inductive indicating switches.

[0029] More preferably, the brake cabinet is equipped with a conversion relay, and the switching signals of the brake on monitoring switch and the brake off monitoring switch are converted into passive nodes and directly transmitted to the LCU monitoring system via the conversion relay.

[0030] Further preferably, it also includes a brake wear monitoring switch for monitoring brake wear. The switching signal of the brake wear monitoring switch is converted into a passive node and directly transmitted to the LCU monitoring system through a conversion relay in the brake cabinet. The brake wear monitoring switch is a strong anti-interference inductive indicating switch.

[0031] More preferably, it also includes an oil temperature and oil level monitoring sensor for monitoring the oil level and oil temperature in the oil tank of the brake hydraulic system. The oil temperature and oil level monitoring sensor is connected to the PLC control module. The PLC control module determines whether the oil temperature and oil level are in normal or fault condition and displays it on the touch screen of the brake cabinet. If it is determined to be a low oil level and / or high oil temperature fault condition, the PLC control module processes it as a fault condition and transmits it to the LCU monitoring system.

[0032] More preferably, the brake cabinet is equipped with a main power supply circuit for supplying power to the brake hydraulic system, a main circuit circuit for the oil pump motor, and a control circuit circuit for the solenoid valve.

[0033] More preferably, the main power supply circuit is powered by two power supply circuits from different sources, and these two power supply circuits from different sources are connected to the main power supply circuit through a dual power automatic switching switch; the main power supply circuit is equipped with a main circuit breaker that controls the on and off of the main power supply circuit.

[0034] More preferably, the main circuit of the oil pump motor includes a first oil pump motor main circuit and a second oil pump motor main circuit, one for use and one for standby; the first oil pump motor main circuit and the second oil pump motor main circuit are connected in parallel on the main power supply circuit and are powered by the main power supply circuit; a first circuit breaker, a first contactor, a first thermal relay and a first oil pump motor are connected in series in the first oil pump motor main circuit; a second circuit breaker, a second contactor, a second thermal relay and a second oil pump motor are connected in series in the second oil pump motor main circuit; both the first contactor and the second contactor are connected to the PLC control module for control and switching; the normally open contacts of the first thermal relay and the second thermal relay are connected to the PLC control module to transmit the closing signal of the normally open contacts after the oil pump motor is overloaded to the PLC control module; the normally closed contacts of the first thermal relay and the second thermal relay are connected in series in the first oil pump motor main circuit and the second oil pump motor main circuit, respectively.

[0035] More preferably, the solenoid valve control circuit provides power to the PLC control module and the solenoid valve group of the brake hydraulic system. The solenoid valve control circuit includes a 220V AC common power supply circuit, a 220V DC backup circuit consisting of an inverter, a dual power automatic converter, a first power module, a second power module (20), a DC redundancy module, and a DCUPS module. The 220V AC common power supply circuit is connected to the first input terminal of the dual power automatic converter, and the 220V DC backup circuit is connected to the second input terminal of the dual power automatic converter. The first power module and the second power module are connected in parallel to the output circuit of the dual power automatic converter. The positive output terminals of the first power module and the second power module are connected to the DC redundancy module, and the positive output terminal of the DC redundancy module is connected to the positive input terminal of the DC UPS module. The negative output terminals of the first power module, the second power module, and the DC redundancy module are all connected to the negative input terminal of the DC UPS module. The output terminal of the DC UPS is connected to the PLC control module and each solenoid valve in the solenoid valve group. The solenoid valve group is controlled by the PLC control module, and the PLC control module controls the on / off state of each solenoid valve in the solenoid valve group.

[0036] More preferably, the 220V AC main power supply circuit is equipped with a third circuit breaker, and the backup circuit is connected in series with a fourth circuit breaker and a DC / AC inverter.

[0037] More preferably, a power monitoring module is connected in parallel in the connection circuit between the first power module, the second power module, the redundancy module, and the DC UPS module. The power monitoring module is connected to the PLC control module, which judges the fault signal of the DC UPS module collected by the power monitoring module. After judging the fault of the DC UPS module, the PLC control module sends the fault signal to the LCU monitoring system.

[0038] More preferably, the DC UPS module is connected to a power supply battery, so that when both the 220V AC power supply circuit and the 220V DC power supply circuit in the solenoid valve control circuit are de-energized, the power supply battery supplies power to the DC UPS module.

[0039] More preferably, the solenoid valve assembly of the brake hydraulic system is installed on the oil supply line and the oil return line between the oil tank and the brake. The solenoid valve assembly includes an upper solenoid valve and a lower solenoid valve. The upper solenoid valve is installed on the oil supply line, and the lower solenoid valve is installed on the oil return line. The input end of the first oil pump motor is connected to the oil tank, and the output end is connected to the oil supply line. The input end of the second oil pump motor is connected to the oil tank, and the output end of the second oil pump motor is connected to the oil supply line. Both the upper and lower solenoid valves are connected to a PLC control module for control.

[0040] More preferably, the gate-opening solenoid valve is a single-coil normally closed solenoid valve that is fully reset when energized and de-energized; the gate-releasing solenoid valve is a single-coil normally open solenoid valve that is fully reset when energized and de-energized.

[0041] More preferably, an accumulator is also installed on the oil supply line, the accumulator is equipped with a pressure relief line, the pressure relief line is equipped with a pressure relief solenoid valve, and the pressure relief line is connected to the return oil line; the pressure relief solenoid valve is controlled and connected to the PLC control module; a pressure sensor is also installed on the accumulator, and the pressure sensor is electrically connected to the PLC control module; the pressure relief solenoid valve is a single-coil normally open solenoid valve that closes when energized and fully resets when de-energized.

[0042] More preferably, the main power supply circuit also includes a fuel tank heater circuit connected in parallel. The fuel tank heater circuit includes a fifth circuit breaker, an NC regulating switch, and a heater. The fifth circuit breaker is used to control the on / off state of the fuel tank heater circuit. The NC regulating switch and the heater are connected in series in the fuel tank heater circuit. A temperature measuring resistor is provided on the heater.

[0043] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0044] 1. This invention completely solves the defect of traditional single-system judgment being prone to accidental braking by adopting a dual control logic of "LCU monitoring system prediction + independent source signal verification of the brake cabinet". The LCU first monitors the GCB trip, guide vane full closure, and speed signals in real time, and outputs a "brake on" command after determining that the conditions are met; the brake cabinet PLC then verifies the original source signals of "guide vane full closure" and "GCB trip" through independent sensors - the two signals come from physically isolated sensors and transmission links. Even if the LCU sends a false command due to line interference or sensor failure, the brake cabinet can still identify the true state of the equipment (such as refusing to brake if the guide vane is not actually fully closed), reducing the risk of brake failure caused by the brake plate breaking and shaft deformation during high-speed operation of the unit to zero, while avoiding control blind spots caused by single signal link failure, and significantly improving the reliability and safety of braking control.

[0045] 2. This invention designs precisely adapted trigger conditions for different braking scenarios, balancing equipment safety and shutdown efficiency: In electric braking mode, it requires "LCU to determine electric braking completion + speed < 5% of rated speed + brake cabinet verification source signal". Low-speed activation reduces brake plate wear and avoids sudden speed drops caused by the superposition of electric and mechanical braking. In non-electric braking (purely mechanical / emergency stop) mode, it adapts to "LCU to determine electric brake blade closure + speed < 20%-30% of rated speed + brake cabinet verification source signal". This relaxes the speed threshold to adapt to the deceleration requirements without electric braking, preventing wear on bearings and other components due to prolonged high-speed rotation of the unit and preventing serious damage to the unit from accidents. Both modes use an independent source signal as the final interlocking condition. Even if the button is accidentally pressed manually near the ground or the remote command is abnormal, braking will still be refused if the source signal is not met, solving the problems of rigid braking logic and insufficient adaptability in traditional braking systems.

[0046] 3. This invention clearly defines differentiated settings for speed thresholds to achieve a balance between "safety and efficiency": the first setting ratio of 5% of rated speed is for low-speed scenarios after electric braking, which can minimize frictional wear between the brake plate and the brake disc, extend the service life of the brake plate, and ensure rapid shutdown of the unit; the second setting ratio of 20%-30% of rated speed is adapted to the deceleration characteristics when there is no electric braking, which avoids equipment damage caused by brake plate impact at excessively high speeds (e.g., >30%), and also prevents a decrease in shutdown efficiency caused by excessively low speeds (e.g., <20%). Both thresholds are linked to the LCU's speed monitoring and the brake cabinet's source signal verification to ensure the accuracy of speed determination and the precision of braking timing.

[0047] 4. This invention integrates the brake engagement / disengagement status signal into the LCU to achieve hierarchical management of "status monitoring and control judgment": The LCU can receive and verify the series signal of the engagement / disengagement monitoring switch in real time (it is only valid if both brake plates are engaged / disengaged), completely avoiding system disturbances caused by false alarms from a single switch; when braking is executed, the LCU can confirm whether the "braking" is in place based on the feedback signal (if no engagement signal is received, an abnormality is indicated), forming a closed-loop control of "command-execution-feedback", solving the problem that the status signal cannot be synchronized to the upper-level system and the fault diagnosis is difficult when using traditional local monitoring. At the same time, the engagement and disengagement switches are mutually self-locking, further eliminating misjudgments of conflicting statuses.

[0048] 5. This invention incorporates a switching relay that converts an active signal into a passive node, addressing the issues of weak anti-interference capability and poor compatibility of traditional active signals (such as DC 24V level) during long-distance transmission. This ensures accurate transmission of the gate-on / gate-off signal to the LCU in complex electromagnetic environments (such as generator plant buildings). The gate-on / gate-off switch is designed in series, and the signal is only considered valid when both gate plates trigger the corresponding state (such as gate-on). This completely avoids misjudgments caused by single switch failures (such as contact oxidation). If contradictory signals of one gate-on and one gate-off occur, the LCU can immediately alarm, guiding maintenance personnel to check for gate plate mechanical jamming or switch damage. This reduces braking anomalies caused by monitoring failures and improves the reliability of status monitoring and fault location efficiency.

[0049] 6. This invention integrates the wear status signal into the LCU and employs a series monitoring logic to achieve "early warning + precise maintenance": When any brake disc reaches the wear threshold, an LCU alarm is triggered, reminding and ensuring the user replaces the worn brake disc in a timely manner. This avoids the risk of missed detection in traditional single-disc monitoring. The LCU can link the wear signal with braking engagement conditions (e.g., locking the brake if wear exceeds the threshold), preventing brake failure due to excessive brake disc wear, excessive frictional heating caused by direct friction between the brake disc substrate and the brake disc, unit vibration, permanent damage or destruction of the brake disc, and excessively high unit maintenance costs. This solves the problems of traditional braking methods lacking a dedicated wear monitoring switch, or the inability to synchronize wear signals to the upper system during local detection, leading to untimely maintenance. Simultaneously, the selection of a strong anti-interference inductive wear switch improves the detection accuracy of the signal in oily and dusty environments (error ≤ 0.1mm).

[0050] 7. The wear monitoring switch of this invention is designed in series to achieve the precise logic of "early warning when any wear exceeds the standard": as long as one of the upper and lower gate plates reaches the wear alarm state, the series signal will trigger the LCU alarm, avoiding the need to set double the contacts in the LCU in the traditional parallel design; at the same time, after the wear signal is connected to the LCU, it can be linked with the unit operation and maintenance system to generate a maintenance work order, specifying the "gate plate replacement" signal, solving the problem of traditional braking methods relying on local indicators of wear, which makes it impossible for operation and maintenance personnel to remotely obtain wear information and has low troubleshooting efficiency, thus reducing downtime and maintenance time and costs.

[0051] 8. In the control method of the present invention, the PLC controls the oil pump motor contactor and the solenoid valve to achieve precise control of the brake hydraulic system: closing the oil pump motor contactor can quickly establish the oil supply pressure, opening the upper solenoid valve and closing the lower solenoid valve to ensure that the hydraulic oil is delivered to the brake in a directional manner, avoiding the operation delay or malfunction in traditional manual control; at the same time, the PLC can monitor the oil supply pressure in real time (through the pressure sensor) to ensure that the braking force is maintained stably after reaching the set value, preventing brake slippage due to insufficient pressure leading to brake failure, or brake timeout, or brake overload caused by excessive braking pressure due to pressure relief valve failure, thus solving the problems of lack of automated closed loop and low braking accuracy in traditional hydraulic control.

[0052] 9. In the control method of this invention, the PLC receives oil temperature and level monitoring signals in real time and determines the status, realizing a hard constraint of "hydraulic medium status - brake engagement": if a low oil level occurs (which may lead to insufficient brake pressure) or a high oil temperature occurs (which may indicate that the motor phase sequence is reversed, the pump is running dry, and pressure cannot be built up normally, and may also lead to a decrease in hydraulic oil viscosity and seal failure), the PLC immediately determines it as a fault and uploads it to the LCU, while simultaneously locking the brake engagement, avoiding the traditional system's execution of braking with a fault, insufficient power, brake failure, or ignoring the hydraulic medium status, etc.; the fault status is displayed on the brake cabinet touch screen, which facilitates on-site maintenance personnel to quickly and timely discover the fault, solving the problem that traditional oil temperature and level alarms are only displayed on the LCU and on-site personnel cannot obtain information in a timely manner.

[0053] 10. The braking control device of the present invention constructs a complete safety system of "monitoring-judgment-execution" through the hierarchical architecture of LCU and brake cabinet and independent sensor configuration: LCU is connected to the guide vane fully closed, GCB trip, and speed sensors, and is responsible for upper-level condition prediction; brake cabinet is connected to independent "guide vane fully closed" and "GCB trip" source signal sensors and signals such as "no braking when speed is greater than 30" transmitted from LCU, and is responsible for lower-level verification; the two types of sensors are physically isolated to prevent common-cause faults (such as the same sensor failure causing LCU and brake cabinet to misjudge at the same time), and solves the defects of traditional devices with single signal links and weak anti-interference capabilities; at the same time, the device is adapted to the aforementioned control methods to ensure the hardware implementation of logics such as dual verification and differentiated braking, and provides equipment support for safe shutdown of the unit.

[0054] 11. In the braking control device of the present invention, the electric brake blade position monitoring sensor is connected to the LCU to provide accurate basis for distinguishing between electric and non-electric braking scenarios: when electric braking is in progress, the LCU confirms the completion of electric braking (blade position closed) through the sensor signal, avoiding the superposition of braking caused by mechanical braking when electric braking is not completed; when non-electric braking is in progress, the LCU confirms that the blade position is closed (electric braking is not engaged), avoiding the braking strategy error caused by misjudging the electric braking status; at the same time, the sensor signal is linked with conditions such as rotation speed and source signal to form a complete safety constraint for non-electric braking scenarios, solving the problem of lack of electric brake blade status monitoring and ambiguous distinction of working conditions in traditional systems.

[0055] 12. In the braking control device of the present invention, the "brake on / off" monitoring switch is connected to the LCU to realize upper-level management of status monitoring: the LCU can remotely obtain the gate's action status in real time, avoiding problems such as accidental braking and inconvenient operation and maintenance; the selection of a strong anti-interference inductive indicator switch improves the reliability of the switch in humid, dusty, and vibrating environments (such as near the brake), with a response time of <1ms, which can accurately capture the instantaneous action of the gate, avoiding signal delay or false alarm caused by the easy jamming, loosening of contacts, and oxidation of contacts of traditional mechanical switches. It works in synergy with the switch series logic and self-locking design to ensure the accuracy of status monitoring. The switch is powered by the stable output of the DC UPS module in the circuit, ensuring that the signal output can be maintained for a short period of time in the event of a sudden power outage. The wiring of the switch maintains a safe distance from other high-voltage circuits (such as the main circuit of the oil pump motor) and other high-current power cables in the circuit. Flame-retardant cables and shielded cables are used to prevent switch damage caused by short circuits and false alarms caused by high current interference. It is linked with the power monitoring module in the circuit to monitor the status of the DC UPS (such as early alarm when the UPS battery is low).

[0056] 13. In the braking control device of this invention, the conversion relay converts the active signal for brake activation / release (such as DC 24V level) into a passive node, solving the compatibility and anti-interference problems of traditional active signals when connected to the LCU: the passive node does not require an independent power supply, and transmits the state only through the on / off state of the contacts, adapting to the switch input interfaces of all LCU models, avoiding signal access failure due to mismatch of LCU input voltage levels; at the same time, the passive node has no voltage attenuation during long-distance transmission, has strong anti-electromagnetic interference capability, avoids misjudgment of the state caused by line interference of traditional active signals, and ensures that the LCU accurately obtains the brake action information. The relay coil is powered by a stable DC 24V power supply in the circuit (such as the output of the DC redundant module), which can avoid relay malfunction caused by fluctuations in the main power supply in the circuit; at the same time, the contact capacity of the relay is matched with the LCU input circuit to prevent signal transmission interruption caused by contact burning; the relay is installed separately from other control components in the circuit (such as PLC output modules) to avoid relay failure caused by poor heat dissipation, and forms a linkage with the power monitoring module in the circuit to monitor the state of the DC redundant module.

[0057] 14. In the braking control device of the present invention, the brake wear monitoring switch is connected to the LCU and adopts a strong anti-interference inductive switch to realize remote monitoring and accurate early warning of wear status: the LCU can acquire wear signals in real time, avoiding the problems of needing to check wear information on-site and untimely maintenance when connected to the PLC in the past; the inductive switch can penetrate oil and dust to accurately identify changes in the thickness of the brake plate, improving the detection accuracy by more than 30%, avoiding the misjudgment of wear caused by the influence of the environment of traditional mechanical switches; at the same time, the series logic of the switch ensures that an alarm is triggered when the wear of any brake plate exceeds the standard, providing early warning of maintenance needs and preventing brake failure.

[0058] 15. In the braking control device of the present invention, after the oil temperature and oil level sensor is connected to the PLC, it can monitor the hydraulic medium status of the braking hydraulic system in real time. After the PLC determines a fault, it displays the fault on the local touch screen (for easy on-site troubleshooting) and uploads the fault to the LCU (for easy remote monitoring), avoiding the information gap of "only local alarm or only remote alarm" in traditional circuits. At the same time, the independent analog interface between the sensor and the PLC avoids the judgment error caused by digital signal interference in the circuit. It is linked with the temperature control logic of the oil tank heater in the circuit to achieve dual protection of "active oil temperature adjustment + fault warning" and prevent braking failure caused by medium problems.

[0059] 16. The brake cabinet in the brake control device of the present invention is provided with a circuit structure that provides power to the brake device. The sensing unit in the device is adapted to the corresponding power supply circuit in the circuit (such as the DC24V power supply of the solenoid valve control circuit). The wiring of the sensor adopts a hard wiring method and is arranged separately from other control signals in the circuit to avoid electromagnetic interference. The modular design of the device (such as independent deployment of PLC, power supply module and sensing unit) facilitates the replacement of faulty parts individually during circuit maintenance, reduces the overall downtime, and works in conjunction with the dual redundancy of the total power supply in the circuit and the one-use-one-standby design of the oil pump motor to improve the overall fault resistance of the device.

[0060] 17. In the braking control device of the present invention, the main power supply adopts two different power sources + dual power automatic switching switch (switching time ≤ 50ms), which completely avoids the power loss of the braking hydraulic system caused by the interruption of a single power supply and solves the defect of "single power supply dependence" in traditional circuits; the main circuit breaker is normally closed and only disconnected during maintenance, which not only meets the requirements of electrical safety isolation, but also reduces the ineffective power supply under non-braking conditions, reduces the aging risk of circuit components being energized for a long time, and adapts to the power demand of other circuits (oil pump, solenoid valve) in the circuit, ensuring that fluctuations in the main power supply do not affect the stability of the branch circuits.

[0061] 18. In the braking control device of the present invention, the main circuit of the oil pump motor is designed with one active and one standby circuit, which, together with an independent circuit breaker, contactor, and thermal relay, realizes "switching of the standby circuit within 5 seconds in case of single circuit failure" to avoid failure of braking pressure build-up; the high breaking capacity (≥10kA) and delayed tripping function of the circuit breaker can quickly cut off the short circuit current and avoid accidental tripping due to motor starting impact; the linkage of "normally closed contact cutting the circuit + normally open contact transmitting the alarm" of the thermal relay prevents the motor from burning out due to overload, solves the risk of "single motor without protection" in traditional circuits, and provides a stable power source for the braking hydraulic system.

[0062] 19. In the braking control device of the present invention, the solenoid valve control circuit has a dual power input of "220V AC normal + 220V DC backup (inverter conversion)", the first / second power modules are backups for each other, the DC redundant module is isolated and decoupled, and the DC UPS + battery emergency power supply forms a "four-layer power supply redundancy", ensuring that the solenoid valve / PLC does not lose power in the whole scenario of "normal power failure - backup power cut-redundancy conversion - UPS emergency"; the third / fourth circuit breaker serves as isolation protection, which not only ensures maintenance safety, but also prevents the back-end fault from expanding, solves the problem of "single power supply and weak anti-interference" in traditional circuits, and ensures the reliable operation of the braking actuator (solenoid valve).

[0063] 20. This invention constructs a full-chain collaborative system of "decision-monitoring-execution" through the synergy of braking control methods and braking control devices, specifically:

[0064] The dual verification logic of "LCU prediction + brake cabinet verification" in the control method relies on the stable power and signal links provided by the circuit structure within the brake cabinet: dual power supply ensures that the brake hydraulic system does not lose power; one-use-one-backup circuit for the oil pump motor ensures uninterrupted brake pressure build-up; and multi-layer redundancy of the solenoid valve control circuit ensures reliable operation of the brake-on / brake-off solenoid valve. For example, when the LCU issues a "brake on" command, the dual power supply automatic switching switch in the circuit can avoid command transmission interruption caused by power fluctuations; the backup oil pump motor can quickly fill in when the main motor fails; and with the accumulator pre-build-up, the braking response time is shortened to ≤200ms, solving the problem of braking delay or failure caused by the traditional "disconnect between control logic and circuit execution," and achieving precise control of "execution upon command issuance and monitoring of the execution process."

[0065] —The design of the braking control device, in which "brake engagement / release / wear signals are converted to passive nodes and connected to the LCU via a switching relay," requires the circuit structure to provide anti-interference support: the DC redundant module in the circuit achieves power isolation and decoupling to avoid power noise from the solenoid valve control circuit from interfering with the sensor signals; the switching relay coil is powered by a stable output from a DC UPS to prevent relay malfunctions caused by main power fluctuations in the circuit; at the same time, the sensor signals are wired separately from high-voltage circuits (such as the main circuit of the oil pump motor) in the circuit to avoid electromagnetic interference. After the integration of these three aspects, the false alarm rate of the status monitoring signal is reduced by more than 90%, and the detection accuracy is improved to ±0.1mm, solving the traditional defect of "sensor signals being susceptible to circuit interference," ensuring that the information on the brake plate status and wear condition obtained by the LCU is true and reliable, and providing an accurate basis for "status-linked interlocking" (such as brake interlocking due to excessive wear) in the control method;

[0066] The differentiated logic in the control method, where "electric braking speed < 5% of rated speed and non-electric braking speed < 20%-30% of rated speed," requires coordinated adaptation between the circuit and the hydraulic system: When electric braking is applied, the electric brake blade position sensor in the circuit accurately reflects the electric braking status, working in conjunction with the oil pump motor's common circuit to achieve smooth braking at low speeds; when non-electric braking is applied, the accumulator in the circuit pre-charges, allowing for rapid pressure build-up at higher speeds and preventing prolonged idling of the unit; simultaneously, the oil temperature and level monitoring and control methods in the circuit are linked, with the oil tank heater automatically heating at low temperatures to ensure the hydraulic oil viscosity matches the braking requirements at different speeds. After integration, this reduces brake wear during normal shutdowns (low-speed operation) and provides rapid response during emergency shutdowns (accumulator emergency pressure supply), covering all operating conditions of the hydro-generator unit and resolving the safety risks or efficiency losses caused by the traditional "circuit's inability to adapt to differentiated braking requirements."

[0067] —The system deeply integrates three elements: "fault-linked interlocking" in the control method (such as braking due to abnormal oil temperature or failure to brake due to insufficient source signal), "series monitoring and alarm" in the device (such as alarm for conflicting gate status), and "power protection and emergency power supply" in the circuit (such as backup battery of DC UPS and circuit breaker trip protection). When a power interruption occurs in the circuit, the DC UPS maintains power supply to the PLC and solenoid valve, and the control method immediately triggers the "emergency braking logic," relying on the accumulator to complete the braking. When the device sensor detects excessive wear of the gate, the control method locks the braking, the corresponding alarm circuit in the circuit is triggered, and the LCU is linked to prompt maintenance. When the oil pump motor in the circuit is overloaded, the thermal relay cuts off the circuit, and the control method automatically switches to the backup motor. The safety closed loop formed by these three elements can cover more than 95% of abnormal scenarios such as "power failure, actuator failure, and sensor failure," completely solving the defect of "a single link failure leading to system failure" in traditional systems, and ensuring that the unit can still be safely shut down under complex operating conditions. Attached Figure Description

[0068] Figure 1 This is a logic diagram of the braking control method of the present invention;

[0069] Figure 2 This is a logic diagram of remote automatic control and near-ground manual braking in the braking control method of the present invention;

[0070] Figure 3 This is a diagram of the remote control and feedback terminals inside the brake cabinet of the brake control device of the present invention;

[0071] Figure 4 This is a schematic diagram showing the connection between the switching relay and the switches for braking, releasing, and wear in the brake cabinet of the braking control device of the present invention;

[0072] Figure 5 This is a circuit diagram of the brake cabinet in the brake control device of the present invention;

[0073] Figure 6 This is a structural diagram of the main power supply circuit in the brake cabinet of the brake control device of the present invention;

[0074] Figure 7 This is a schematic diagram of the main circuit structure of the oil pump motor in the brake cabinet of the braking control device of the present invention.

[0075] Figure 8 This is a circuit diagram of the solenoid valve control circuit inside the brake cabinet in the brake control device of the present invention;

[0076] Figure 9 This is a diagram showing the dual-power supply structure of the solenoid valve control circuit in the brake cabinet of the braking control device of the present invention.

[0077] Figure 10This is a structural diagram of the dual-power automatic converter output circuit in the solenoid valve control circuit within the brake cabinet of the braking control device of the present invention.

[0078] Figure 11 This is a structural diagram of the brake hydraulic system in the brake control device of the present invention;

[0079] Figure 12 This is a circuit diagram of the oil tank heater inside the brake cabinet in the brake control device of the present invention;

[0080] Figure reference numerals: 1. Main power supply circuit; 2. Oil pump motor main circuit; 3. Solenoid valve control circuit; 4. Dual power automatic transfer switch; 5. Main circuit breaker; 6. First oil pump motor main circuit; 7. Second oil pump motor main circuit; 8. First circuit breaker; 9. First contactor; 10. First thermal relay; 11. First oil pump motor; 12. Second circuit breaker; 13. Second contactor; 14. Second thermal relay; 15. Second oil pump motor; 16. 220V AC common power supply circuit; 17. Backup circuit; 18. Dual power automatic transfer switch; 19. First power module; 20. Second power module; 21. DC redundancy module; 22. DC... UPS module, 23. Fuel tank, 24. Brake, 25. Fuel supply line, 26. Fuel return line, 27. Brake-on solenoid valve, 28. Brake-off solenoid valve, 29. Accumulator, 30. Pressure relief line, 31. Pressure relief solenoid valve, 32. Third circuit breaker, 33. Fourth circuit breaker, 34. DC / AC inverter, 35. Power monitoring module, 36. Power supply battery, 37. Fuel tank heater circuit, 38. Fifth circuit breaker, 39. NC regulating switch, 40. Heater; 41. Brake-on monitoring switch, 42. Brake-off monitoring switch, 43. Transfer relay, 44. Brake wear monitoring switch. Detailed Implementation

[0081] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0082] Example 1

[0083] As a preferred embodiment of the present invention, please refer to the appendix to the specification. Figure 1 As shown in the figure, this embodiment discloses a braking control method applicable to hydro-generator sets. Specifically, the braking control method is as follows:

[0084] The LCU monitoring system monitors the GCB trip signal, guide vane full closure signal, and speed signal in real time.

[0085] The PLC control module of the brake cabinet receives the "guide vane fully closed" source signal transmitted separately from the switch signal on the guide vane and the "GCB open" source signal transmitted separately from the switch signal on the GCB in real time.

[0086] Among them, the "guide vane fully closed" source signal transmitted to the PLC control module of the brake cabinet and the guide vane fully closed signal transmitted to the LCU monitoring system are independent signals; the "GCB trip" source signal transmitted to the PLC control module of the brake cabinet and the GCB trip signal transmitted to the LCU monitoring system are independent signals.

[0087] When the unit is braking, the LCU monitoring system detects that the GCB is open, the guide vanes are fully closed, and the unit speed meets the braking requirements. When the LCU monitoring system outputs a "brake engage" command to the PLC control module of the brake cabinet, the PLC control module of the brake cabinet receives the "brake engage" command and determines that it has received the "guide vanes fully closed" source signal and the "GCB open" source signal. The PLC control module then controls the unit's braking hydraulic system to perform "brake engage".

[0088] As an example of this embodiment, both the signal sensor and the monitoring sensor mentioned above can be mechanical switches, such as single-switch dual-position output mechanical switches, typically limit switches, such as the LX19 series and ME8108 series. These switches have two sets of independent contacts (normally open and normally closed). When the guide vane or GCB reaches a specific position (e.g., guide vane fully closed, GCB open), the mechanical trigger mechanism operates, and the two sets of contacts simultaneously switch states (normally open to normally closed, normally closed to normally open). One set of contact signals can be directly sent to the brake cabinet PLC as a source signal, while the other set is connected to the LCU monitoring system, realizing the function of "one switch generating two independent signals." The two sets of signals are physically isolated and their states are strictly correlated, facilitating logic verification. Another example is a dual-independent switch type mechanical switch, which can use two microswitches of the same model (e.g., KW11 series, V-156-1C25 series) or rotary position switches, respectively installed at the position detection points of the guide vane or GCB. When the equipment is in place, both switches are triggered simultaneously. The output signal of one switch is transmitted to the PLC of the brake cabinet, and the other is transmitted to the LCU monitoring system. The two switches are installed and wired independently, forming a completely physically isolated signal chain. Even if one switch fails (such as contact oxidation failure), the other can still output a signal normally, ensuring system redundancy.

[0089] In this embodiment, the aforementioned guide vane full-off signal and GCB tripping signal refer to signals emitted directly from the mechanical switch without any intermediate relay. That is, the guide vane full-off signal and GCB tripping signal are directly taken from the original contacts of the mechanical switch, without passing through any intermediate conversion module or logic processing unit, and are sent directly to the brake cabinet PLC via cable. This "point-to-point" transmission method avoids signal distortion caused by module failure or program loopholes during relay, ensuring that the brake cabinet receives the most original feedback on the equipment status. For example, the mechanical switch signal indicating GCB tripping is directly transmitted to the PLC, eliminating interference or misjudgment of the signal from intermediate links.

[0090] The system requires the brake cabinet to simultaneously verify both the "source signal" and the "LCU command signal," and braking can only be activated if both conditions are met. Even if one signal is lost due to a loose cable or oxidation of the connector, the independent existence of the other signal can prevent accidental braking activation, forming a "necessary" link redundancy. For example, if the command signal from the LCU to the brake cabinet is interrupted due to a cable fault, the brake cabinet can directly lock the brake based on the absence of the source signal, avoiding a control blind spot caused by a single link failure.

[0091] The effectiveness of the local manual braking button strictly depends on source signal verification: the manual button operation only takes effect after the brake cabinet confirms "GCB tripped" and "guide vanes fully closed" through the source signal; if the GCB is not tripped or the guide vanes are not fully closed, even if the manual button is accidentally pressed, the brake cabinet will refuse to execute because the source signal is not satisfied. This design forcibly binds manual operation to the equipment's safety status at the hardware level, completely eliminating accidental braking caused by human error during high-speed operation, and solving the safety hazard of traditional manual control lacking hard interlocking.

[0092] Whether it's remote automatic braking or near-ground manual braking, the verification standards for the source signal are completely consistent, ensuring uniform safety thresholds across different operating modes. For example, during near-ground manual braking, even if the operator misjudges the unit's status, the braking cabinet will still use the source signal as the final basis, only performing braking after confirming that the GCB is open, the guide vanes are fully closed, and the speed meets the standard. This avoids a loosening of safety standards due to scenario switching, ensuring controllable risks under all operating conditions.

[0093] This provides an extra layer of protection, with both events corroborating each other. Since the signal is transmitted via cable, to prevent signal loss due to cable loosening, braking is only activated after both signals are confirmed. Most importantly, the additional direct source signal prevents accidental activation when manually applying the brakes at high speeds. This way, after interlocking, braking will only be activated when the GCB is in position and the guide vanes are fully closed, even if the manual button is pressed by mistake. Otherwise, if the GCB is not in position and the guide vanes are not fully closed, braking will not be activated even if the manual button is pressed by mistake.

[0094] During remote automatic braking, when the LCU monitoring system determines that the GCB trip, guide vane fully closed, and speed less than the rated speed of the unit all meet the braking requirements, it outputs a "brake engage" signal to the PLC control module of the brake cabinet. After receiving the "brake engage" signal, the PLC control module of the brake cabinet sequentially judges the guide vane fully closed source signal and the GCB trip source signal it monitors. After determining that the guide vane fully closed source signal is "guide vane fully closed" and the GCB trip source signal is "GCB tripped", it executes mechanical braking to control the braking of the unit.

[0095] Example 2

[0096] As another preferred embodiment of the present invention, this embodiment further supplements and elaborates on the technical solution of the present invention based on Embodiment 1 above. In this embodiment, for near-ground manual braking scenarios or remote automatic braking scenarios, the two control logics are refined according to whether the unit uses electric braking, further improving the accuracy and safety of braking control. (Refer to the appendix of the specification.) Figure 2 As shown, during near-ground manual braking or remote automatic braking, when the unit uses electric braking, both near-ground manual braking and remote automatic braking must meet the coordinated conditions of "electric braking completed + speed reaching the target + source signal interlocking":

[0097] The LCU monitoring system determines the electric braking process by collecting the "electric brake blade opening signal" from the braking control circuit: when the electric brake blade is in the open state, it determines that electric braking has been completed or not engaged; only when the electric brake blade opening signal is valid can the subsequent braking process begin. This design avoids the sudden drop in unit speed and brake plate overload caused by the superposition of electric braking and mechanical braking, ensuring a smooth transition in the braking process.

[0098] The LCU monitoring system monitors the unit's speed in real time. Only when the speed drops below 5% of the unit's rated speed (the first set ratio) will it output a pre-signal to the brake cabinet PLC allowing manual braking. This threshold balances equipment safety and braking efficiency: low-speed operation reduces brake wear while ensuring rapid unit shutdown.

[0099] After receiving a manual braking command, the PLC control module of the brake cabinet must independently verify two original source signals: mechanical braking will only be executed if the guide vane fully closed source signal is "guide vane fully closed" and the GCB trip source signal is "GCB tripped," and these signals completely match the LCU's electric braking completion signal and speed target achievement signal. If either source signal fails to meet the requirements (e.g., the guide vane is not fully closed), the PLC will forcibly lock out even if the manual button is accidentally pressed, eliminating the risk of accidental high-speed activation.

[0100] When performing manual braking near the ground or automatic braking remotely, if the unit does not use electric braking, both manual braking near the ground and automatic braking remotely employ the adaptation logic of "electric brake blade status + higher speed threshold + source signal interlock":

[0101] The LCU monitoring system needs to confirm that the "electric brake switch is closed" (i.e., the electric brake system is not engaged) to avoid signal misinterpretation under non-electric brake conditions and to ensure that the control logic is consistent with the unit configuration.

[0102] Because there is no electric braking to assist deceleration, the speed threshold is relaxed to less than 20% to 30% of the unit's rated speed (second set ratio). This threshold satisfies both the safety braking requirements (avoiding brake impact at excessively high speeds) and the shutdown efficiency requirements when there is no electric braking, preventing the unit from idling at low speeds for too long.

[0103] Similar to the electric braking operation, the brake cabinet PLC must verify that the guide vane fully closed source signal is "guide vane fully closed" and the GCB open source signal is "GCB open," and that these match the LCU's electric brake blade status signal and speed compliance signal before braking is executed. Even in the event of manual misoperation, if the source signals do not meet the requirements, the system will still lock out, ensuring safety.

[0104] This embodiment distinguishes between different control logics for electric braking configurations, enabling precise matching of braking strategies with actual unit operating conditions: electric braking ensures equipment lifespan at low speeds, while non-electric braking balances efficiency and safety with adaptability thresholds. At the same time, it always uses independent source signals as the final judgment basis, achieving the dual goals of "flexible adaptation + intrinsic safety" for near-ground manual operation.

[0105] In the above embodiment, the touch screen of the brake cabinet has manual and automatic states. First, rotate to manual state, and then make a judgment according to the above logic. If the judgment is successful, the operator presses the manual brake button inside the brake cabinet to perform manual braking; if the judgment is unsuccessful, even if the operator presses the manual brake button, the manual brake button will spring back and will not perform braking.

[0106] Example 3

[0107] As another preferred embodiment of the present invention, this embodiment, based on Embodiment 1 or Embodiment 2, refines and optimizes the monitoring logic and signal transmission mechanism for the brake's engagement / disengagement state, further enhancing the collaborative reliability of "LCU monitoring - signal conversion - status verification," as shown in the appendix to the specification. Figure 4 As shown, the specific technical solution is as follows:

[0108] Each brake set has two independent upper and lower brake discs equipped with a strong anti-interference inductive brake-on monitoring switch and a strong anti-interference inductive brake-off monitoring switch (such as model BI10-M30-AD4X). These switches have vibration resistance (vibration frequency ≤50Hz) and electromagnetic interference resistance (insulation resistance ≥100MΩ) characteristics, with a detection accuracy of ±0.1mm. They can penetrate the oil and dust environment near the brake and accurately capture the small displacement of the brake disc (the amount of displacement of the brake disc when it is engaged and when it is disengaged).

[0109] Monitoring switches of the same type are connected in series: the upper brake flap's braking monitoring switch and the lower brake flap's braking monitoring switch are connected in series and then connected to the coil circuit of the changeover relay 43 in the brake cabinet; similarly, the upper brake flap's releasing brake monitoring switch and the lower brake flap's releasing brake monitoring switch are connected in series and then connected to the coil circuit of another set of changeover relays 43. The series circuit is only connected and the coil of the changeover relay 43 is energized when both brake flaps trigger the corresponding state (e.g., both braking flap switches are closed when braking, and both releasing brake flap switches are closed when releasing the brake).

[0110] The changeover relay 43 adopts a single-coil, dual-contact type (such as model HH52P). Its normally open contact serves as a "passive node signal" directly connected to the switch input module of the LCU monitoring system. When the series circuit is connected (the relay is energized), the normally open contact closes, transmitting a "lock-on" or "lock-off" signal to the LCU; when the series circuit is disconnected (the relay is de-energized), the contact resets, and the signal is interrupted. This design avoids distortion caused by voltage attenuation and electromagnetic interference during long-distance transmission of traditional active signals (such as DC24V level), while also being compatible with the LCU's standardized passive node input interface, covering mainstream LCU models (such as NARI PCS-9600 series and ABB AC800 series).

[0111] The LCU monitoring system collects three core signals in real time and performs logical judgments: unit status signals (GCB trip signal, guide vane fully closed signal, unit speed signal, passive node signal after the brake-on monitoring switch is connected in series, and passive node signal after the brake-off monitoring switch is connected in series); only when all the above signals meet the braking activation requirements will the LCU output a "activate braking" command to the PLC control module of the brake cabinet to avoid activating braking with a fault. After receiving the "activate braking" command, the PLC control module drives the oil pump motor main circuit contactor to close, and simultaneously controls the energization of the brake-on solenoid valve and the brake-off solenoid valve. During this process: when both brake plates are fully engaged, the brake-on monitoring switch series circuit is activated, the conversion relay 43 is energized, and its passive node feeds back "brake in place" to the LCU; after receiving the "brake in place" signal, the LCU, combined with the pressure value of the oil supply pipeline pressure sensor (connected to the PLC, pressure signal uploaded to the LCU), determines that the braking is successfully activated, and displays "braking normal" on the monitoring interface. If the LCU does not receive a "gate in place" signal after the PLC issues a gate-up command, the LCU immediately sends a "brake abnormality" command to the PLC. The PLC controls the gate-up solenoid valve to lose power, the gate-release solenoid valve to lose power (connecting the return oil), and the oil pump motor to stop. At the same time, the LCU triggers an audible and visual alarm, indicating "gate-up failed, gate or switch needs to be checked".

[0112] When the LCU detects that the gate opening monitoring switch signal and the gate release monitoring switch signal exist simultaneously or that a single signal flashes for a long time, it immediately determines that there is a contradiction in the gate status or a switch failure. The specific abnormality type is displayed on the monitoring interface, and a maintenance work order is generated, specifying the brake location and switch type to be investigated.

[0113] Example 4

[0114] As another preferred embodiment of the present invention, this embodiment, based on Embodiment 1, Embodiment 2, or Embodiment 3, deeply optimizes the monitoring accuracy, signal reliability, and fault early warning mechanism of brake wear status, and constructs a full-chain wear management logic of precise monitoring - passive transmission - linkage interlocking. The specific technical solution is as follows:

[0115] Each brake set has two independent upper and lower brake discs equipped with a strong anti-interference inductive wear monitoring switch. The sensor is installed in a fixed position on the brake disc bracket, and its sensing surface is kept parallel to the wear side of the brake disc with a spacing error of ≤1mm to avoid false triggering due to installation deviation.

[0116] The LCU monitoring system receives and monitors wear status signals from the upper and lower brake discs of each brake unit in the brake hydraulic system in real time. Based on these signals, the LCU determines the wear condition of the brake discs. If the LCU determines that the brake disc wear is normal, and the GCB is open, the guide vanes are fully closed, and the unit speed meets the braking activation requirements, it outputs a "activate braking" command to the PLC control module of the brake cabinet. The brake disc wear status monitoring signal is converted into a passive node and directly transmitted to the LCU monitoring system via a relay within the brake cabinet. The wear status monitoring switches for the upper and lower brake discs are connected in series; if either brake disc reaches the wear alarm state, it indicates that the wear is complete and replacement is required.

[0117] The wear monitoring switch for the upper and lower brake discs is connected in series to the coil circuit of the same changeover relay 43. This design follows the principle of alarming if either disc exceeds a certain threshold. That is, when the wear of either disc reaches a preset threshold, the corresponding wear switch is disconnected, the series circuit is de-energized, and the changeover relay 43 is de-energized. Only when neither disc reaches the wear threshold is the series circuit activated and the relay energized.

[0118] The normally closed contact of the conversion relay 43 serves as the passive node signal for the wear state, directly connected to the switch input module of the LCU monitoring system. The specific logic is as follows: Normal state (both petals are not worn beyond the limit): The relay is energized, the normally closed contact opens, and the LCU receives a "wear normal" signal; Wear beyond the limit state (any petal meets the standard): The relay is de-energized, the normally closed contact closes, and the LCU receives a wear alarm signal. The passive node does not require an independent power supply, completely solving the signal distortion problem caused by voltage attenuation and electromagnetic interference during long-distance (≤100m) transmission of traditional active signals (such as DC24V level), while perfectly adapting to the standardized switch input interface of the LCU.

[0119] The LCU monitoring system employs a dual verification logic of wear status and unit status. It only outputs a "brake on" command to the brake cabinet PLC when all of the following conditions are met: The LCU does not receive a "wear on" passive node signal (i.e., the normally closed contact of the changeover relay 43 is open), determining that neither brake plate has reached the wear threshold and the braking capacity meets requirements; the LCU receives and verifies the GCB trip signal, the guide vane fully closed signal, and the unit speed signal. If the LCU detects a "wear on" signal, it blocks the "brake on" command output, refusing to send a braking command to the PLC even if the unit status meets the requirements, to prevent brake failure due to excessive brake plate wear; the LCU monitoring system then issues a wear on" alarm.

[0120] Example 5

[0121] As another preferred embodiment of the present invention, this embodiment, based on embodiments 1, 2, 3, or 4, refines and optimizes the execution logic of "brake engagement," oil temperature and level monitoring, and fault linkage mechanism of the brake hydraulic system, constructing a closed-loop control system of "precise execution - real-time monitoring - fault interlocking." The specific technical solution is as follows:

[0122] The PLC control module controls the unit's brake hydraulic system to perform "brake activation." Specifically, the PLC control module controls the contactor on the main circuit of the oil pump motor to close and controls the upper solenoid valve on the oil supply line between the oil tank and the brake to open, supplying oil to the brake. Simultaneously, it controls the lower solenoid valve on the return line between the oil tank and the brake to close, disconnecting the return line and activating braking. The PLC control module receives real-time oil temperature and level monitoring signals from the oil temperature and level sensors installed in the oil tank. The PLC control module determines whether the oil temperature and level are normal or faulty, displaying this information on the brake cabinet's touchscreen display. If a low oil level and / or high oil temperature fault is detected, the PLC control module treats it as a fault and transmits the information to the LCU monitoring system.

[0123] In this embodiment, two types of monitoring elements are integrated into the oil tank to achieve comprehensive monitoring of the hydraulic medium's condition. For example, an oil temperature sensor, using a PT100 platinum resistance temperature sensor, is installed in the oil immersion area in the middle of the tank to collect oil temperature signals in real time. The oil level sensor uses a float-type level switch, whose output signal is connected to the PLC digital input module; the contact closes when the oil level is low and opens when the oil level is high. The PLC control module performs logical judgments on the collected oil temperature and level signals and displays them in real time on the brake cabinet touchscreen.

[0124] Example 6

[0125] As another preferred embodiment of the present invention, this embodiment provides a braking control device suitable for hydro-generator sets. This device is adapted to the braking control method for hydro-generator sets described in Embodiment 1 above. Through redundant design of the hardware architecture and independent configuration of the signal links, it achieves safe and controllable operation of the entire "monitoring-determination-execution" process. The specific technical solution is as follows:

[0126] The braking control device includes an LCU monitoring system, a brake cabinet, and a brake hydraulic system. The brake cabinet houses a PLC control module, and the LCU monitoring system establishes a communication connection with the PLC control module. It also includes a guide vane full-close monitoring sensor for acquiring the guide vane full-close signal, a GCB trip monitoring sensor for acquiring the GCB trip signal, a speed monitoring sensor for acquiring the unit speed, a guide vane full-close source signal monitoring sensor for acquiring the guide vane full-close source signal, and a GCB trip source signal monitoring sensor for acquiring the GCB trip source signal. The guide vane full-close monitoring sensor, GCB trip monitoring sensor, and speed monitoring sensor are connected to the LCU monitoring system, while the guide vane full-close source signal monitoring sensor and the GCB trip source signal monitoring sensor are connected to the PLC control module.

[0127] The PLC control module receives "engage braking" or "retract braking" commands from the LCU monitoring system in real time, and controls the braking hydraulic system to perform "engage braking" or "retract braking" according to the received commands.

[0128] Example 7

[0129] As another preferred embodiment of the present invention, this embodiment further supplements and elaborates on the technical solution of the present invention based on the above embodiment 6. The braking control device of this embodiment can be adapted to the braking control method for hydro-generator sets described in embodiments 2, 3, 4 or 5. The specific technical solution is as follows.

[0130] As one embodiment of this invention, the braking control device further includes an electric brake blade position monitoring sensor for monitoring the opening and closing of the electric brake blade. The electric brake blade position signal is connected to the LCU monitoring system, providing a direct basis for the LCU to determine the electric braking / non-electric braking mode. When the electric brake blade is closed, the "electric braking" logic is triggered, and when the blade is opened, the "non-electric braking" logic is triggered. The specific control principle is as described in Embodiment 2 above.

[0131] In another embodiment of this invention, the braking control device further includes a brake engagement monitoring switch 41 and a brake release monitoring switch 42 for monitoring the brake position status. The switching signals of both the brake engagement monitoring switch 41 and the brake release monitoring switch 42 are connected to the LCU monitoring system. The brake engagement monitoring switch 41 and the brake release monitoring switch 42 are strong anti-interference inductive indicating switches. A conversion relay 43 is installed inside the brake cabinet. The switching signals of the brake engagement monitoring switch 41 and the brake release monitoring switch 42 are converted by the conversion relay 43 into passive nodes that are directly transmitted to the LCU monitoring system (same as the series monitoring mechanism in Embodiment 3).

[0132] As another implementation of this embodiment, the braking control device also includes a brake wear monitoring switch 44 for monitoring the wear of the brake brake. The switching signal of the brake wear monitoring switch 44 is converted into a passive node and directly transmitted to the LCU monitoring system through the conversion relay 43 in the brake cabinet. The brake wear monitoring switch 44 is a strong anti-interference inductive indicator switch (same as the wear monitoring logic in embodiment 4).

[0133] As another embodiment of this invention, the brake control device further includes an oil temperature and oil level monitoring sensor for monitoring the oil level and oil temperature in the oil tank of the brake hydraulic system. The oil temperature and oil level monitoring sensor is connected to the PLC control module. The PLC control module determines whether the oil temperature and oil level are in normal or fault condition and displays the result on the touch screen of the brake cabinet. If the condition is determined to be a low oil level and / or high oil temperature fault condition, the PLC control module processes it as a fault condition and transmits it to the LCU monitoring system (same as the monitoring mechanism in embodiment 5).

[0134] Example 8

[0135] As another preferred embodiment of the present invention, this embodiment is a further detailed supplement and explanation of the technical solution of the present invention based on the above-described embodiment 6 or embodiment 7. In this embodiment, reference is made to the appendix to the specification. Figure 5 As shown, the brake cabinet is equipped with a main power supply circuit 1 for supplying power to the brake hydraulic system, a main circuit circuit 2 for the oil pump motor, and a solenoid valve control circuit 3.

[0136] For details, please refer to the instruction manual appendix. Figure 6 As shown, the main power supply circuit 1 adopts a dual-path independent power supply architecture. The two power sources are from two different power supply circuits (such as different bus sections of the plant's low-voltage section). They are connected to the main circuit of the system through a dual-power automatic transfer switch 4 (such as the ATSE series, with a switching time ≤50ms). That is, the two different power supply circuits are connected to the main power supply circuit 1 through the dual-power automatic transfer switch 4. The main power supply circuit 1 is equipped with a main circuit breaker 5 that controls the on / off state of the main power supply circuit 1. In the main power supply circuit 1, the main circuit breaker 5 is normally closed and is only opened during circuit maintenance and other operating conditions. It is used to isolate the power supply during maintenance, ensure the safety of maintenance personnel, and meet electrical safety regulations.

[0137] The core advantage of the above design is that when any power supply is interrupted due to grid fluctuations, line faults, or equipment maintenance, the dual power automatic transfer switch 4 can instantly switch to another power supply, avoiding the failure of the brake hydraulic system due to power loss, and ensuring the continuity of power during emergency shutdown from the source; the "normal closing and on-demand opening" logic of the main circuit breaker 5 reduces the ineffective power supply under non-braking conditions, reduces the risk of aging of circuit components due to long-term energization, and saves energy.

[0138] Refer to the instruction manual appendix Figure 7 As shown, the main circuit 2 of the oil pump motor includes a first oil pump motor main circuit 6 (one in use and one in standby) and a second oil pump motor main circuit 7. The first oil pump motor main circuit 6 and the second oil pump motor main circuit 7 are connected in parallel to the main power supply circuit 1 and are powered by the main power supply circuit 1. The first oil pump motor main circuit 6 is connected in series with a first circuit breaker 8, a first contactor 9, a first thermal relay 10, and a first oil pump motor 11. The second oil pump motor main circuit 7 is connected in series with a second circuit breaker 12, a second contactor 13, a second thermal relay 14, and a second oil pump motor 15. The first contactor 9 and the second contactor 13 are both connected to the PLC control module and are controlled by the PLC control module to switch on and off. The normally open contacts of the first thermal relay 10 and the second thermal relay 14 are connected to the PLC control module to transmit the closing signal of the normally open contacts after the oil pump motor is overloaded to the PLC control module. The normally closed contacts of the first thermal relay 10 and the second thermal relay 14 are connected in series in the first oil pump motor main circuit 6 and the second oil pump motor main circuit 7, respectively.

[0139] In the main circuit 2 of the oil pump motor mentioned above, the first circuit breaker 8 and the second circuit breaker 12 are normally closed and used for short-circuit protection. They automatically trip when a short-circuit fault occurs. They have high breaking capacity (breaking capacity ≥10kA) and three-phase simultaneous breaking characteristics, which can quickly cut off the short-circuit fault current and prevent the residual voltage from having a secondary impact on the motor. In view of the characteristics of three-phase motors, such as large starting current (about 5-7 times the rated current) and easy stalling, the circuit breaker has a built-in time delay tripping function (the delay time can be set to 0.1-1s) to avoid false tripping caused by the inrush current at the moment of starting.

[0140] In the main circuit 2 of the oil pump motor described above, the first contactor 9 and the second contactor 13 are both connected to the PLC control module and controlled by the PLC control module to switch on and off. They are generally normally open and only close when the PLC receives a braking command to drive the corresponding oil pump motor to start. The two contactors are interlocked (the PLC program is set with the logic "the second contactor 13 is prohibited from operating when the first contactor 9 is closed") to prevent overload caused by the simultaneous start of the two motors.

[0141] In the aforementioned main circuit 2 of the oil pump motor, the normally open contacts of the first thermal relay 10 and the second thermal relay 14 are connected to the PLC control module to prevent motor overload. When the oil pump motor is overloaded, the normally open contacts close and transmit a signal to the PLC control module. The normally closed contacts of the first thermal relay 10 and the second thermal relay 14 are connected in series in the first oil pump motor main circuit 6 and the second oil pump motor main circuit 7, respectively. When one of the motors experiences overcurrent or overload, the normally closed contact of the thermal relay in that circuit automatically opens, and the normally open contact automatically closes. After the normally open contact closes, the signal enters the PLC control module, which then issues an alarm signal to prevent the brake hydraulic system from failing to build up pressure.

[0142] Refer to the instruction manual appendix Figure 8 Appendix Figure 9 and attached Figure 10 As shown, the solenoid valve control circuit 3 supplies power to the solenoid valve group of the PLC control module and the brake hydraulic system. It adopts a design of "dual power supply switching + redundancy conversion + uninterrupted power supply", and its specific configuration is as follows:

[0143] The solenoid valve control circuit 3 includes a 220V AC main power supply circuit 16, a 220V DC backup circuit 17 composed of an inverter, a dual-power automatic converter 18, a first power module 19, a second power module 20, a DC redundancy module 21, and a DC UPS module 22. The 220V AC main power supply circuit 16 is connected to the first input terminal of the dual-power automatic converter 18, and the 220V DC backup circuit 17 is connected to the second input terminal of the dual-power automatic converter 18. The first power module 19 and the second power module 20 are connected in parallel to the output circuit of the dual-power automatic converter 18. The positive output terminals of the first power module 19 and the second power module 20 are connected to the DC redundancy module 21, and the positive output terminal of the DC redundancy module 21 is connected to the positive input terminal of the DC UPS module 22. The negative output terminals of the first power module 19, the second power module 20, and the DC redundancy module 21 are all connected to the negative input terminal of the DC UPS module 22. The UPS output is connected to the PLC control module and each solenoid valve in the solenoid valve group; the solenoid valve group is controlled by the PLC control module, which controls the on / off state of each solenoid valve in the solenoid valve group.

[0144] In the aforementioned solenoid valve control circuit 3, the function of the dual-power automatic converter 18 is to automatically switch to the backup circuit 17 when the 220V AC main power supply circuit 16 fails, ensuring the reliability and continuity of power supply. The first power module 19 and the second power module 20 serve as backups for each other, both powered by the DC redundant module 21, preventing the DC redundant module 21 from having no input power in case of a fault. The DC redundant module 21 provides electrical isolation and decoupling for the first power module 19 and the second power module 20, preventing a fault in one path from propagating to the other, ensuring that the two power supplies do not interfere with each other, eliminating the effects of circulating current, ensuring that the system will not shut down when one path loses power, and also has the functions of current sharing, load balancing, and ensuring voltage stability; at the same time, the DC redundant module 21 converts 220V AC to 24V DC output to power the DC UPS module 22.

[0145] Example 9

[0146] As another preferred embodiment of the present invention, this embodiment further supplements and elaborates on the technical solution of the present invention based on the above-described embodiment 8. The power protection, status monitoring, and emergency power supply system for the solenoid valve control circuit are designed in detail, and the circuit reliability is improved through a multi-level protection mechanism. Refer to the appendix of the specification. Figure 8 Appendix Figure 9 and attached Figure 10 As shown, the specific technical solution is as follows:

[0147] A third circuit breaker 32 is installed on the 220V AC main power supply circuit 16, and a fourth circuit breaker 33 and a DC / AC inverter 34 are connected in series on the backup circuit 17. The third circuit breaker 32 is connected in series at the front end of the 220V AC main power supply circuit 16 and is a miniature circuit breaker with a rated current of 10A (breaking capacity ≥6kA), normally in a manually closed state. When debugging or maintaining downstream components (such as the dual-power automatic converter 18, power module), the third circuit breaker 32 can be manually disconnected to cut off the 220VAC input, ensuring complete power loss to the downstream circuit and meeting the "no-live operation" requirement in electrical safety regulations. When a short circuit occurs in the downstream circuit (such as power module breakdown) or a sustained overload (current >10A), the third circuit breaker 32 can automatically trip within 0.1 seconds, cutting off the faulty circuit and preventing the spread of fire or arc to the plant's AC power grid.

[0148] The 220V DC backup power supply circuit is connected in series with the fourth circuit breaker 33 and the DC / AC inverter 34. The fourth circuit breaker 33 has the same specifications as the third circuit breaker 32 (rated current 10A), and is normally in the manually closed state. It can be used as an isolation point for the 220VDC power supply. When it is disconnected during maintenance, it can ensure that the inverter and subsequent circuits are de-energized. When the inverter has an internal short circuit or abnormal output, the fourth circuit breaker 33 will automatically trip to prevent the plant's DC power supply panel from being damaged by overcurrent.

[0149] In a preferred embodiment, a power monitoring module 35 is connected in parallel in the connection circuit between the first power module 19, the second power module 20, the redundant module, and the DCUPS module 22. The power monitoring module 35 is connected to a PLC control module. The PLC control module determines the fault signal of the DC UPS module 22 collected by the power monitoring module 35. If a fault is detected in the DC UPS module 22, the PLC control module sends the fault signal to the LCU monitoring system. The power monitoring module 35 monitors the DC UPS module 22 to ensure the reliability of its power supply. When the DC redundant module 21 fails, a power fault alarm will occur. This signal will be sent to the LCU monitoring system of the braking system via the PLC control module, providing a signal indicating whether braking is appropriate.

[0150] As a preferred embodiment, the DC UPS module 22 is connected to a power supply battery 36. When both the 220V AC power supply circuit and the 220V DC power supply circuit in the solenoid valve control circuit 3 are de-energized, the power supply battery 36 supplies power to the solenoid valve.

[0151] This embodiment constructs a full life-cycle power supply guarantee system for the solenoid valve control circuit through a three-level design of "input protection - status monitoring - emergency power supply". It not only meets the maintenance safety specifications, but also can quickly respond and ensure the braking function in the event of power failure, further improving the system's risk resistance capability.

[0152] Example 10

[0153] As another preferred embodiment of the present invention, this embodiment further supplements and elaborates on the technical solution of the present invention based on the above-described embodiments 8 or 9. In this embodiment, the linkage mechanism between the brake hydraulic system and the control circuit is further refined, and the selection characteristics of the solenoid valve group, the pipeline connection logic, and the collaborative control process of the PLC and LCU are clarified, as detailed in the appendix to the specification. Figure 11 As shown, the specific technical solution is as follows:

[0154] The solenoid valve group of the brake hydraulic system is installed on the oil supply line 25 and the oil return line 26 between the oil tank 23 and the brake 24. The solenoid valve group includes an upper solenoid valve 27 and a lower solenoid valve 28.

[0155] Upper gate solenoid valve 27: Installed on the main oil supply line from oil tank 23 to brake 24, it adopts a single coil normally closed direct-acting solenoid valve (such as model ZCT-15, nominal diameter 15mm). Its core characteristic is "power on and power off, full reset": Under normal conditions, the valve core is kept closed by the spring force, blocking the flow of hydraulic oil to brake 24; when receiving a PLC control signal (DC24V), the electromagnetic force overcomes the spring force to push the valve core open, and high-pressure hydraulic oil (pressure established by oil pump motor) enters brake 24 through oil supply line 25, driving the upper and lower brake discs to fit against the brake disc, realizing the braking action.

[0156] Brake release solenoid valve 28: Installed on the main return oil line from brake 24 to oil tank 23, it adopts a single coil normally open direct-acting solenoid valve (such as model ZCT-20, nominal diameter 20mm). Its core characteristic is "power off, power on, full reset": Under normal conditions, the valve core remains open to ensure that the hydraulic oil in brake 24 can flow back to oil tank 23 through return oil line 26; when receiving PLC control signal, the valve core closes the return oil passage to maintain the pressure stability in brake 24.

[0157] Both types of solenoid valves feature a zero-leakage design: the valve seat and valve core are precision ground, and the valve stem interface is equipped with double O-ring seals to ensure that hydraulic oil leakage is ≤0.1mL / min when closed, avoiding both oil waste and abnormal brake pressure decay. Simultaneously, the solenoid valve response time is ≤50ms, enabling rapid execution of PLC commands and reducing braking action delay.

[0158] The first oil pump motor 11 and the second oil pump motor 15 serve as hydraulic power sources, forming a closed-loop control with the solenoid valve group. The input ends of both oil pump motors are connected to the oil tank 23 through an oil suction filter, and the output ends are connected to the main oil supply line after being merged through high-pressure oil pipes, and connected to the inlet end of the upper gate solenoid valve 27. Under normal working conditions, the PLC selects one of the motors to operate according to preset logic (e.g., the first oil pump motor 11 is the main motor and the second oil pump motor 15 is the backup motor), and starts the motor by driving the corresponding contactor (the first contactor 9 or the second contactor 13), pressurizing the hydraulic oil in the oil tank 23 and delivering it to the oil supply line 25. When the oil pump motor is running, the pressure of the oil supply line 25 is monitored in real time by a pressure sensor, and the signal is fed back to the PLC to ensure that the system pressure is stable within the braking range.

[0159] The PLC control module and the LCU monitoring system of the braking system establish real-time communication via industrial Ethernet (communication protocol Modbus TCP / IP), forming a hierarchical control logic of "upper-level decision-making - lower-level execution". The specific process is as follows:

[0160] 1. Braking command trigger: The LCU monitoring system monitors the unit status in real time (such as GCB trip signal, guide vane closing signal, speed signal, etc.). When it determines that the braking activation conditions are met (such as speed ≤ 5% or 20% of rated speed, depending on whether the unit uses electric braking), it sends a "brake activation" command (switch signal or communication message) to the PLC.

[0161] 2. PLC execution logic:

[0162] —Power supply and circuit verification: The PLC first confirms that the main power supply circuit 1 is normal (the dual power automatic transfer switch 4 has no switching abnormality), and the circuit breaker (first circuit breaker 8) and thermal relay (first thermal relay 10) of the selected oil pump motor main circuit (such as the first oil pump motor main circuit 6) are in normal condition (no tripping or overload signal).

[0163] —Drive the oil pump motor: The PLC outputs a control signal to close the first contactor 9, start the first oil pump motor 11 to run, and establish the oil supply pressure;

[0164] —Control the operation of the solenoid valve: After the pressure sensor on the oil supply line 25 detects that the oil supply pressure has reached the set value (e.g., ≥110 bar), the PLC simultaneously outputs an energizing signal to the "up gate solenoid valve 27" (to open the oil supply) and an energizing signal to the "release gate solenoid valve 28" (to close the return oil). The pressure inside the brake 24 rises rapidly, pushing the gate plate to close.

[0165] —Status feedback: The PLC sends a "brake engaged successfully" signal (including pressure value, solenoid valve status, etc.) back to the LCU, which then displays the real-time braking status on the monitoring interface.

[0166] If the PLC detects an abnormality during execution (such as the pressure not reaching the target within 30 seconds after the oil pump motor starts, or the solenoid valve jamming causing an abnormal passage), the following actions will be triggered immediately:

[0167] Automatically switch to the backup oil pump motor (such as the second oil pump motor main circuit 7) and repeat the braking process;

[0168] If the backup circuit is still abnormal, a "brake failure" alarm signal is sent to the LCU, and the brake release solenoid valve 28 is de-energized (opens the return oil) and the oil pump motor is stopped to prevent the system from operating with a fault.

[0169] In this embodiment, the "one-in-use, one-out-of-service" design of the oil pump motor ensures that if a single motor fails, the backup motor can be switched on within 5 seconds to ensure uninterrupted hydraulic power. The solenoid valve adopts a direct-acting structure, eliminating the need for a pilot valve and reducing the risk of intermediate link failures. Its "power-off reset" feature can automatically restore to a safe state (upper gate valve closed, lower gate valve open) when the control power is interrupted, avoiding gate malfunction. The communication link between the PLC and LCU uses fiber optic backup, combined with hard-wired switch signal verification, to prevent instruction loss due to communication interruption.

[0170] This embodiment deeply integrates electrical control and hydraulic execution by clarifying the selection characteristics of the solenoid valve, refining the linkage logic of "motor-solenoid valve-brake 24" and the collaborative process of PLC and LCU. This ensures the accuracy of braking action (response time ≤200ms) and improves the system's fault resistance through multi-layer redundancy design, realizing the "controllable, measurable and reliable" braking process of the hydro-generator unit.

[0171] Refer to the instruction manual appendix Figure 11 As shown, an accumulator 29 and a matching pressure relief device are introduced into the brake hydraulic system. The braking response speed and fault resistance are improved through a "pre-pressure build-up + emergency redundancy" design. The specific technical solution is as follows:

[0172] An accumulator 29 is connected in parallel to the oil supply line 25. Its inlet is connected to the oil supply line 25 of the first oil pump motor 11 and the second oil pump motor 15, and its outlet is connected to the oil supply line 25 at the front end of the upper gate solenoid valve 27. The accumulator 29 can pre-store pressurized oil. After selecting near-ground or remote braking control, the system first executes the "ready function", that is, the accumulator 29 is pressurized. According to the motor selection, the first contactor 9 or the second contactor 13 is closed to start the corresponding oil pump motor (first oil pump motor 11 or second oil pump motor 15), and the pressure relief solenoid valve 31 is energized and closed. According to the preset charging pressure on the PLC, the pressure sensor on the accumulator 29 detects the charging value, and the charging stops after the preset pressure is reached.

[0173] As an example, when the PLC control module receives a braking command, it closes the first contactor 9 or the second contactor 13 according to the motor selection, starting the corresponding oil pump motor (first oil pump motor 11 or second oil pump motor 15). Simultaneously, the PLC outputs an energized signal to the "closing solenoid valve 27" (to open the oil supply) and an energized signal to the "releasing solenoid valve 28" (to close the return oil). The pressure inside the brake 24 rises rapidly, pushing the brake plate to close. At this time, because there is hydraulic oil at a set pressure in the accumulator 29, an immediate braking response can be achieved.

[0174] As another example, when the PLC control module receives a braking command, it outputs an energized signal to the "braking solenoid valve 27" (to open the oil supply) and an energized signal to the "releasing solenoid valve 28" (to close the return oil). The pressure inside the brake 24 rises rapidly, pushing the brake plate to close. Braking is achieved using the pressure in the accumulator 29. Upon receiving a release command from near or far, the PLC controls the braking solenoid valve 27 to close (cut off the oil supply) and the releasing solenoid valve 28 to open (enable the return oil). The hydraulic oil in the brake 24 flows back to the oil tank 23 through the return oil line 26. When the pressure sensor on the oil supply line 25 at the rear end of the braking solenoid valve 27 detects that the pressure has dropped to 0 bar, the release is determined to be complete. After the release, the PLC controls the oil pump motor to start, re-pressurizing the accumulator 29 to a ready state, waiting for the next braking command.

[0175] As another example, the PLC simultaneously starts the oil pump motor (such as the first oil pump motor 11) and opens the upper solenoid valve 27 and closes the lower solenoid valve 28; the oil pump motor provides continuous pressure, and the accumulator 29 supplements the instantaneous flow, together supplying oil to the brake 24 to ensure that the pressure rises quickly to the set value.

[0176] As another example, if the first oil pump motor 11 fails to start or trips during operation, the PLC immediately closes the upper solenoid valve 27 and triggers an alarm. At the same time, it relies solely on the accumulator 29 to release the pre-stored pressure oil and supplies oil to the brake 24 through the upper solenoid valve 27 (the pressure of the accumulator 29 can maintain the pressure requirement for a single braking action) to complete the braking action.

[0177] When the oil pump motor starts or stops or the load changes, the accumulator 29 absorbs pressure shocks, keeping the pressure fluctuations in the oil supply line 25 within a reasonable range. When both oil pump motors fail, the braking action is completed independently using the pressurized oil stored in the accumulator 29.

[0178] The accumulator 29 is connected to an independent pressure relief pipeline 30 at its bottom. A pressure relief solenoid valve 31 is installed on the pipeline, and its outlet is connected to the return oil pipeline 26. It adopts a single-coil normally closed direct-acting solenoid valve (10mm diameter) with the characteristic of "closing when energized and fully resetting when de-energized" - under normal conditions (de-energized), the valve opens and the pressure of the accumulator 29 can be released through the pressure relief pipeline 30; when energized, the valve closes, blocking the pressure relief passage and ensuring that the accumulator 29 stores pressure normally.

[0179] The pressure relief solenoid valve 31 is controlled by the PLC and is kept energized. Only when the accumulator 29 is under maintenance, the braking system is under maintenance, or all external power supplies (AC380V, AC220V, and DC220V) are disconnected for 30 minutes, will the PLC de-energize the pressure relief solenoid valve 31, and the branch of the accumulator 29 will release current and pressure. When all external power supplies are disconnected, the PLC will send a power failure alarm signal to the LCU. If the external power supply has not been restored after 30 minutes, the PLC will directly cut off the UPS, including disconnecting the battery inside the UPS, which is equivalent to shutting down the machine directly.

[0180] Because the accumulator 29 pre-stores high-pressure oil, there is no need to wait for the oil pump motor to build up pressure after the braking command is triggered. The time for the brake 24 pressure to rise from 0 to the braking pressure is greatly shortened, reducing the unit's high-speed idling time. When both oil pump motors fail (such as circuit breaker tripping or motor burnout), the accumulator 29 can independently provide the pressure oil required for one braking operation, avoiding braking failure due to power source failure, which is especially suitable for emergency shutdown scenarios. After the preparation stage pressurization is completed, the oil pump motor does not need to run continuously, only replenishing pressure when the pressure is below the threshold, reducing the motor's no-load energy consumption. Enhanced pressure stability: The buffering effect of the accumulator 29 reduces the pressure fluctuation amplitude of the oil supply line 25, reducing fatigue damage to solenoid valves and pipe joints, and extending the life of hydraulic components.

[0181] This embodiment, through the introduction of accumulator 29 and pressure relief system, constructs a dual-mode power guarantee system of "active pre-pressure building up + passive emergency use", which not only improves the timeliness and stability of braking action, but also further strengthens the risk resistance capability of the hydro-generator unit braking system through redundancy design under fault conditions, thus achieving the dual goals of "efficient braking" and "safety redundancy".

[0182] Refer to the instruction manual appendix Figure 5 and attached Figure 12 As shown, a fuel tank heater circuit 37 is also connected in parallel to the main power supply circuit 1. The fuel tank heater circuit 37 includes a fifth circuit breaker 38, an NC regulating switch 39, and a heater 40. The fifth circuit breaker 38 is used to control the on / off state of the fuel tank heater circuit 37, and the NC regulating switch 39 and the heater 40 are connected in series in the fuel tank heater circuit 37. A temperature sensing resistor is provided on the heater 40.

[0183] The oil tank heater circuit 37 prevents the oil temperature in the oil tank 23 from becoming too low or too high. The oil temperature is measured by a temperature-sensing resistor integrated on the heater 40. It automatically heats the oil when the temperature is too low and automatically disconnects when the temperature returns to normal. The NC regulating switch 39 is normally open, and the fifth circuit breaker 38 is normally closed. The fifth circuit breaker 38 serves as an electrical isolation power supply for the heater 40 and NC regulating switch 39 during maintenance. A separate oil temperature and level fault monitoring sensor is installed inside the oil tank 23. Upon detecting a fault, the PLC control module outputs a fault signal to the LCU monitoring system.

Claims

1. A braking control method applicable to hydro-generator sets, characterized in that: The specific braking control method is as follows: The LCU monitoring system monitors the GCB trip signal, guide vane full closure signal, and speed signal in real time. The PLC control module of the brake cabinet receives the guide vane full shut-off signal transmitted separately from the switch signal on the guide vane and the GCB open-circuit signal transmitted separately from the switch signal on the GCB in real time. Among them, the guide vane full-off source signal transmitted to the PLC control module of the brake cabinet and the guide vane full-off signal transmitted to the LCU monitoring system are independent signals; the GCB trip source signal transmitted to the PLC control module of the brake cabinet and the GCB trip signal transmitted to the LCU monitoring system are independent signals. When the unit is braking, the LCU monitoring system monitors that the GCB trip, the guide vanes are fully closed, and the unit speed meets the braking requirements. When the LCU monitoring system outputs a braking command to the PLC control module of the brake cabinet, the PLC control module of the brake cabinet receives the braking command and determines that it has received the guide vane fully closed source signal and the GCB trip source signal. The PLC control module then controls the unit's braking hydraulic system to perform braking. When the unit uses electric braking mode, the LCU monitoring system determines that the unit has completed electric braking. At the same time, the LCU monitoring system determines that the unit speed is less than the first set ratio of the unit's rated speed. The PLC control module of the brake cabinet has received the guide vane full shut-off signal and the GCB open-circuit signal. The PLC control module controls the unit's braking hydraulic system to perform braking. If the unit does not use electric braking mode, but uses pure mechanical braking or emergency shutdown mode, after the LCU monitoring system determines that the electric brake switch is closed and the unit speed is less than the second set ratio of the unit's rated speed, the PLC control module of the brake cabinet has received the guide vane full shut-off signal and the GCB open-circuit signal. The PLC control module controls the unit's braking hydraulic system to perform braking.

2. The braking control method for a hydro-generator set as described in claim 1, characterized in that: The first set percentage of the rated speed of the unit is 5%; the second set percentage of the rated speed of the unit is 20% to 30%.

3. A braking control method for a hydro-generator set as described in claim 1 or 2, characterized in that: The LCU monitoring system receives and monitors the switch signals of the brake on-off monitoring switch (41) and brake off-off monitoring switch (42) of the upper and lower brakes of each brake in the brake hydraulic system in real time. The LCU monitoring system determines the position status of the brake based on the received on-off or off-off switch signals. When the LCU monitoring system determines that the brake is in normal condition and that the GCB is open, the guide vanes are fully closed, and the unit speed meets the braking requirements, it outputs a braking command to the PLC control module of the brake cabinet. When the PLC control module controls the brake hydraulic system to perform braking, the brake on-off monitoring switch (41) and brake off-off monitoring switch (42) provide feedback on the braking execution status to the LCU monitoring system.

4. The braking control method for a hydro-generator set as described in claim 3, characterized in that: The brake cabinet is equipped with a conversion relay (43). The switching signals of the brake on-state monitoring switch (41) and the brake off-state monitoring switch (42) are converted by the conversion relay (43) and directly transmitted to the LCU monitoring system via a passive node. The brake on-state monitoring switches (41) of the upper and lower brakes of the brake are connected in series. When both the upper and lower brakes of the brake are in the on-state, it indicates that the brake is in the on-state. The brake off-state monitoring switches (42) of the upper and lower brakes of the brake are connected in series. When both the upper and lower brakes of the brake are in the off-state, it indicates that the brake is in the off-state.

5. A braking control method for a hydro-generator set as described in claim 1 or 2, characterized in that: The LCU monitoring system receives and monitors the wear status monitoring signals of the upper and lower brake discs of each brake in the brake hydraulic system in real time. The LCU monitoring system determines the wear status of the brake based on the wear status monitoring signals. When the LCU monitoring system determines that the wear status of the brake is normal and that the GCB is open, the guide vanes are fully closed, and the unit speed meets the braking requirements, it outputs a braking command to the PLC control module of the brake cabinet.

6. The braking control method for a hydro-generator set as described in claim 5, characterized in that: The wear status monitoring signal of the brake is converted into a passive node and directly transmitted to the LCU monitoring system through the conversion relay (43) in the brake cabinet; the wear status monitoring switches of the upper and lower brakes are set in series. When either the upper or lower brake reaches the wear alarm state, it indicates that the wear has reached the point of replacement.

7. A braking control method for a hydro-generator set as described in claim 1 or 2, characterized in that: The PLC control module controls the unit's braking hydraulic system to perform braking. Specifically, the PLC control module controls the contactor on the main circuit of the oil pump motor to close, and controls the upper solenoid valve (27) on the oil supply line (25) between the oil tank (23) and the brake (24) to open, so that the oil supply line (25) supplies oil to the brake (24); and controls the release solenoid valve (28) on the return oil line (26) between the oil tank (23) and the brake (24) to close, so that the return oil line (26) is disconnected, and braking is performed.

8. The braking control method for a hydro-generator set as described in claim 7, characterized in that: The PLC control module receives the oil temperature and oil level monitoring signals from the oil temperature and oil level monitoring sensors installed in the oil tank (23) in real time. The PLC control module determines whether the oil temperature and oil level are in normal or fault condition and displays them on the touch screen of the brake cabinet. If it is determined to be a low oil level and / or high oil temperature fault condition, the PLC control module processes it as a fault condition and transmits it to the LCU monitoring system.

9. A braking control device based on any one of claims 1-8, applicable to a braking control method for a hydro-generator set, characterized in that: It includes an LCU monitoring system, a brake cabinet, and a brake hydraulic system. The brake cabinet is equipped with a PLC control module, and the LCU monitoring system establishes a communication connection with the PLC control module. It also includes a guide vane full-close monitoring sensor for acquiring the guide vane full-close signal, a GCB trip monitoring sensor for acquiring the GCB trip signal, a speed monitoring sensor for acquiring the unit speed, a guide vane full-close source signal monitoring sensor for acquiring the guide vane full-close source signal, and a GCB trip source signal monitoring sensor for acquiring the GCB trip source signal; the guide vane full-close monitoring sensor, the GCB trip monitoring sensor, and the speed monitoring sensor are connected to the LCU monitoring system, and the guide vane full-close source signal monitoring sensor and the GCB trip source signal monitoring sensor are connected to the PLC control module; The PLC control module receives braking or de-braking commands from the LCU monitoring system in real time, and controls the braking hydraulic system to perform braking or de-braking according to the received commands.

10. The braking control device as described in claim 9, characterized in that: It also includes an electric brake blade position monitoring sensor for monitoring the opening and closing of the electric brake blade, and the electric brake blade position signal is connected to the LCU monitoring system.

11. The braking control device as described in claim 9 or 10, characterized in that: It also includes a brake engagement monitoring switch (41) and a brake release monitoring switch (42) for monitoring the position status of the brake. The switch signals of the brake engagement monitoring switch (41) and the brake release monitoring switch (42) are both connected to the LCU monitoring system. The brake engagement monitoring switch (41) and the brake release monitoring switch (42) are strong anti-interference inductive indicator switches.

12. The braking control device as described in claim 11, characterized in that: The brake cabinet is equipped with a conversion relay (43). The switching signals of the brake on monitoring switch (41) and the brake off monitoring switch (42) are converted by the conversion relay (43) into passive nodes and directly transmitted to the LCU monitoring system.

13. The braking control device as described in claim 9 or 10, characterized in that: It also includes a brake wear monitoring switch (44) for monitoring brake wear. The switching signal of the brake wear monitoring switch (44) is converted into a passive node and directly transmitted to the LCU monitoring system through the conversion relay (43) in the brake cabinet. The brake wear monitoring switch (44) is a strong anti-interference inductive indicator switch.

14. The braking control device as described in claim 9 or 10, characterized in that: It also includes oil temperature and oil level monitoring sensors for monitoring the oil level and oil temperature in the oil tank of the brake hydraulic system. The oil temperature and oil level monitoring sensors are connected to the PLC control module. The PLC control module determines whether the oil temperature and oil level are in normal or fault condition and displays the result on the touch screen of the brake cabinet. If the condition is determined to be low oil level and / or high oil temperature fault condition, the PLC control module processes it as a fault condition and transmits it to the LCU monitoring system.

15. The braking control device as described in claim 9, characterized in that: The brake cabinet is equipped with a main power supply circuit (1) for supplying power to the brake hydraulic system, a main circuit circuit (2) for the oil pump motor, and a solenoid valve control circuit (3).

16. The braking control device as described in claim 15, characterized in that: The main power supply circuit (1) is powered by two power supply circuits from different sources. These two power supply circuits from different sources are connected to the main power supply circuit (1) through a dual power automatic switching switch (4). The main power supply circuit (1) is equipped with a main circuit breaker (5) that controls the on and off of the main power supply circuit (1).

17. The braking control device as described in claim 15, characterized in that: The main circuit (2) of the oil pump motor includes a first oil pump motor main circuit (6) and a second oil pump motor main circuit (7), one for use and one for standby. The first oil pump motor main circuit (6) and the second oil pump motor main circuit (7) are connected in parallel to the main power supply circuit (1) and are powered by the main power supply circuit (1). The first oil pump motor main circuit (6) is connected in series with the first circuit breaker (8), the first contactor (9), the first thermal relay (10), and the first oil pump motor (11). The second oil pump motor main circuit (7) is connected in series with the second circuit breaker (12), the second contactor (9), and the first contactor (11). 13) Second thermal relay (14) and second oil pump motor (15); First contactor (9) and second contactor (13) are both connected to the PLC control module and controlled by the PLC control module to switch on and off; the normally open contacts of the first thermal relay (10) and the second thermal relay (14) are connected to the PLC control module to transmit the signal of the normally open contact closing after the oil pump motor is overloaded to the PLC control module; the normally closed contacts of the first thermal relay (10) and the second thermal relay (14) are connected in series in the main circuit (6) of the first oil pump motor and the main circuit (7) of the second oil pump motor, respectively.

18. The braking control device as claimed in claim 15, characterized in that: The solenoid valve control circuit (3) supplies power to the solenoid valve group of the PLC control module and the brake hydraulic system. The solenoid valve control circuit (3) includes a 220VAC common power supply circuit (16), a 220V DC backup circuit (17) composed of an inverter, a dual power automatic converter (18), a first power module (19), a second power module (20), a DC redundancy module (21), and a DC UPS module (22). The 220V AC common power supply circuit (16) is connected to the first input terminal of the dual power automatic converter (18), and the 220V DC backup circuit (17) is connected to the second input terminal of the dual power automatic converter (18). The first power module (19) and the second power module (20) are connected in parallel to the output circuit of the dual power automatic converter (18). The positive output terminals of the first power module (19) and the second power module (20) are connected to the DC redundancy module (21), and the positive output terminal of the DC redundancy module (21) is connected to the DC UPS module (22). The positive input terminal of the UPS module (22); the negative output terminals of the first power module (19), the second power module (20) and the DC redundancy module (21) are all connected to the negative input terminal of the DC UPS module (22); the output terminal of the DC UPS is connected to the PLC control module and each solenoid valve in the solenoid valve group; the solenoid valve group is controlled and connected to the PLC control module, and the PLC control module controls the opening and closing of each solenoid valve in the solenoid valve group.

19. The braking control device as claimed in claim 18, characterized in that: The 220V AC common power supply circuit (16) is equipped with a third circuit breaker (32), and the backup circuit (17) is connected in series with a fourth circuit breaker (33) and a DC / AC inverter (34).

20. The braking control device as claimed in claim 18, characterized in that: A power monitoring module (35) is connected in parallel in the connection circuit between the first power module (19), the second power module (20), the redundancy module and the DC UPS module (22). The power monitoring module (35) is connected to the PLC control module. The PLC control module judges the fault signal of the DC UPS module (22) collected by the power monitoring module (35). After judging the fault of the DC UPS module (22), the PLC control module sends its fault signal to the LCU monitoring system.

21. The braking control device as claimed in claim 20, characterized in that: The DC UPS module (22) is connected to a power supply battery (36). When both the 220V AC power supply circuit and the 220V DC power supply circuit in the solenoid valve control circuit (3) are de-energized, the power supply battery (36) supplies power to the DC UPS module (22).

22. The braking control device according to any one of claims 15-21, characterized in that: The solenoid valve group of the brake hydraulic system is installed on the oil supply line (25) and the return line (26) between the oil tank (23) and the brake (24). The solenoid valve group includes an upper solenoid valve (27) and a lower solenoid valve (28). The upper solenoid valve (27) is installed on the oil supply line (25), and the lower solenoid valve (28) is installed on the return line (26). The input end of the first oil pump motor (11) is connected to the oil tank (23), and the output end is connected to the oil supply line (25). The input end of the second oil pump motor (15) is connected to the oil tank (23), and the output end of the second oil pump motor (15) is connected to the oil supply line (25). The upper solenoid valve (27) and the lower solenoid valve (28) are both connected to the PLC control module.

23. The braking control device as described in claim 22, characterized in that: The upper gate solenoid valve (27) is a single-coil normally closed solenoid valve that is fully reset when energized and de-energized; the lower gate solenoid valve (28) is a single-coil normally open solenoid valve that is fully reset when energized and de-energized.

24. The braking control device as described in claim 22, characterized in that: An accumulator (29) is also installed on the oil supply line (25). The accumulator (29) is equipped with a pressure relief line (30). A pressure relief solenoid valve (31) is installed on the pressure relief line (30). The pressure relief line (30) is connected to the return oil line (26). The pressure relief solenoid valve (31) is connected to the PLC control module. A pressure sensor is also installed on the accumulator (29). The pressure sensor is electrically connected to the PLC control module. The pressure relief solenoid valve (31) is a single-coil normally open solenoid valve that closes when energized and fully resets when de-energized.

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