Over-current protection method and system in starting power generation process of three-stage power generation system

Abstract

The invention provides an overcurrent protection method and system for a starting power generation process of a three-stage power generation system, and the method comprises the steps: modeling and dividing: carrying out the modeling of a three-stage power generator, and dividing the starting power generation process into different stages; and a monitoring isolation step: monitoring working parameters of different stages by using the built over-current protection device, and completing the isolation of the over-current fault according to a monitoring result. According to the structural characteristics and the finite-state machine theory of the three-stage generator, modeling is carried out on the starting power generation working process of the three-stage generator, and control over all stages in the whole starting power generation working process is achieved by analyzing all working stages of the three-stage generator and the conditions needed by stage transformation; a protection device is established for an overcurrent fault which is very easy to occur in the no-load boosting process of the generator, and an overcurrent signal is used as a condition for the action of the protection device, so that the overcurrent fault can be quickly and efficiently monitored and isolated.

Description

Technical Field

[0001] The present invention relates to the field of starting and power generation control of aviation power generation systems, and in particular, to an overcurrent protection method and system for the starting and power generation process of a three-stage power generation system, and in particular to an overcurrent protection method for the starting and power generation process of a three-stage power generation system based on finite state machine theory. Background Art

[0002] The starting and generating technology of the three-stage generator refers to the three-stage generator in a stationary state, using the motor mode as the power source to generate torque for starting; when the rotor speed reaches the disengagement speed, the external electric excitation source is disconnected and the generator mode is switched to work, changing the output target from torque to output electrical energy, and providing electrical energy to the electrical load of the aircraft, realizing the dual functions of starting and power supply. In the starting stage, the three-stage generator is connected to the electric power and initially operates at a constant torque; when the motor speed reaches the ignition speed, the motor operates at a constant power, and when it reaches the disengagement speed, the electric power is disconnected, and the motor current begins to decrease to zero; as the rotor rotates with inertia, the magnetic flux lines of the main generator are cut, and the main generator begins to output electrical energy; when it comes to the no-load boost stage, the closed-loop damping of the circuit is very small, and the output voltage will continue to rise. At the same time, this process is also prone to overcurrent faults, so it is necessary to design an overcurrent fault protection device. When the output voltage of the main generator reaches the rated voltage, the filter capacitor and the load are connected at the output end, and the voltage regulation control stage begins. In this stage, the main generator starts to supply power to the load and adjusts the voltage to keep the voltage stable. When the speed reaches the rated speed, the voltage regulating load is disconnected and the aircraft power load is connected, entering the power generation operation stage.

[0003] In order to make the three-stage generator complete the switch from the starting stage to the electric power cut-off stage, it is necessary to connect the generator to an external power source as an excitation source, which is realized through the switch state of the relay. The switching of the switch is controlled by the method of finite state machine theory. Finite state machine (FSM), also known as finite state automaton, represents a mathematical model of a finite number of states and the transfer and actions between these states. It combines the characteristics of discrete and continuous systems. These systems contain both discrete events and state changes, as well as continuous dynamic changes. It is particularly suitable for dealing with complex systems that need to consider both time continuity and logical state changes. Its continuous dynamics are usually described by differential equations, while discrete dynamics involve switching between states. When the continuous variable reaches the switching condition, the function of its continuous variable is updated and the work is performed according to the new function.

[0004] Patent document CN116208036A discloses a voltage regulation system for a three-stage generator. By fitting the PMG voltage curve, the excitation power supply Vo can be controlled to change less with the speed, so that the duty cycle of the excitation power tube is within a better range, ensuring the stability of the generator output voltage regulation. However, the technical method adopted by the patent document is essentially different from that adopted by the present invention. Summary of the invention

[0005] In view of the defects in the prior art, an object of the present invention is to provide an overcurrent protection method and system for the start-up power generation process of a three-stage power generation system.

[0006] According to the present invention, an overcurrent protection method for a three-stage power generation system during a power generation start-up process includes:

[0007] Modeling division steps: Model the three-stage generator and divide the process of starting and generating electricity into different stages;

[0008] Monitoring and isolation steps: Use the constructed overcurrent protection device to monitor the working parameters at different stages, and complete the isolation of the overcurrent fault based on the monitoring results.

[0009] Preferably, the three-stage generator includes three coaxially connected motors, namely a permanent magnet synchronous motor and two electrically excited synchronous motors; the electrically excited synchronous motor includes an auxiliary exciter and a main generator.

[0010] Preferably, the different stages into which the process of starting the power generation work is divided include:

[0011] Starting stage: The three-stage generator is connected to the electric power and initially runs at a constant torque. When the motor speed reaches the ignition speed, the motor runs at a constant power.

[0012] Electric power cut-off stage: Electric power is cut off, the current gradually drops to zero, and the main generator starts to output electric energy;

[0013] No-load boost stage: the output voltage continues to rise under no-load;

[0014] Voltage regulation control stage: When the output voltage of the main generator reaches the rated voltage, the filter capacitor and the load are connected at the output end; the main generator starts to supply power to the load and regulates the voltage to keep the voltage stable;

[0015] Power generation operation stage: disconnect the voltage regulating load, connect the aircraft power load, and provide stable power supply to the aircraft load;

[0016] When a certain stage meets the switching conditions, it enters the next working stage; the switching conditions include reaching the disengagement speed, completing the electric power cut-off, loading filtering and reaching the rated speed.

[0017] Preferably, when the disengagement speed is reached, the operating condition of the three-stage generator changes from the starting stage to the electric power cut-off stage; when the electric power cut-off is completed, the operating condition of the three-stage generator changes from the electric power cut-off stage to the no-load boost stage; when the loading filtering is completed, the operating condition of the three-stage generator changes from the no-load boost stage to the voltage regulation control stage; when the rated speed is reached, the operating condition of the three-stage generator changes from the voltage regulation control stage to the power generation operation stage.

[0018] Preferably, the overcurrent protection device can remove the fault through a circuit breaker within a limited time; the working conditions of the overcurrent protection device include:

[0019] Normal operation: At this time, the three-stage generator operates under the preset working conditions;

[0020] Observation at a certain time: when receiving an overcurrent signal, wait for a certain period of time to observe whether the overcurrent signal disappears;

[0021] To be processed: If the overcurrent signal does not disappear after the observation time, it is ready to enter the isolation protection stage;

[0022] Device abnormality: At this time, the overcurrent protection device fails and fails to enter the protection state;

[0023] Isolation protection: The circuit breaker switch is in the disconnected state, successfully isolating the overcurrent fault.

[0024] Preferably, a signal monitoring device is added to the constructed overcurrent protection model, and when an overcurrent signal, a timing completion signal, a timing interruption signal, a device abnormality signal or a device action signal is received, the model starts to act;

[0025] The overcurrent signal includes when the current monitored exceeds 1.5 times the rated current, the protection device of the three-stage generator switches from normal operation to standby observation;

[0026] The timing completion signal includes that the timing of the waiting time observation stage is completely completed, the overcurrent signal has not disappeared, and the preset allowable overcurrent existence time is exceeded, and the protection device operating state is switched from waiting time observation to imminent processing;

[0027] The timing interruption signal includes the disappearance of the overcurrent signal, the timing interruption, and the preset allowable existence time is not exceeded, and the working condition of the protection device is switched from waiting observation to normal operation;

[0028] The device abnormality signal includes a fault in the overcurrent protection device, inability to process the overcurrent fault, and the protection device operating state switching from about to be processed to device abnormality;

[0029] The device action signal includes that the overcurrent protection device has not failed, the processing of the overcurrent fault has been completed, and the working state of the protection device has been switched from processing to isolation protection.

[0030] According to the present invention, an overcurrent protection system for starting a power generation process of a three-stage power generation system is provided, comprising:

[0031] Modeling and division module: Model the three-stage generator and divide the process of starting and generating electricity into different stages;

[0032] Monitoring and isolation module: Use the built overcurrent protection device to monitor the working parameters at different stages, and complete the isolation of overcurrent faults based on the monitoring results.

[0033] Preferably, the three-stage generator includes three coaxially connected motors, namely a permanent magnet synchronous motor and two electrically excited synchronous motors; the electrically excited synchronous motor includes an auxiliary exciter and a main generator.

[0034] Preferably, the different stages into which the process of starting the power generation work is divided include:

[0035] Starting stage: The three-stage generator is connected to the electric power and initially runs at a constant torque. When the motor speed reaches the ignition speed, the motor runs at a constant power.

[0036] Electric power cut-off stage: Electric power is cut off, the current gradually drops to zero, and the main generator starts to output electric energy;

[0037] No-load boost stage: the output voltage continues to rise under no-load;

[0038] Voltage regulation control stage: When the output voltage of the main generator reaches the rated voltage, the filter capacitor and the load are connected at the output end; the main generator starts to supply power to the load and regulates the voltage to keep the voltage stable;

[0039] Power generation operation stage: disconnect the voltage regulating load, connect the aircraft power load, and provide stable power supply to the aircraft load;

[0040] When a certain stage meets the switching conditions, it enters the next working stage; the switching conditions include reaching the disengagement speed, completing the electric power cut-off, loading filtering and reaching the rated speed.

[0041] Preferably, when the disengagement speed is reached, the operating condition of the three-stage generator changes from the starting stage to the electric power cut-off stage; when the electric power cut-off is completed, the operating condition of the three-stage generator changes from the electric power cut-off stage to the no-load boost stage; when the loading filtering is completed, the operating condition of the three-stage generator changes from the no-load boost stage to the voltage regulation control stage; when the rated speed is reached, the operating condition of the three-stage generator changes from the voltage regulation control stage to the power generation operation stage.

[0042] Preferably, the overcurrent protection device can remove the fault through a circuit breaker within a limited time; the working conditions of the overcurrent protection device include:

[0043] Normal operation: At this time, the three-stage generator operates under the preset working conditions;

[0044] Observation at a certain time: when receiving an overcurrent signal, wait for a certain period of time to observe whether the overcurrent signal disappears;

[0045] To be processed: If the overcurrent signal does not disappear after the observation time, it is ready to enter the isolation protection stage;

[0046] Device abnormality: At this time, the overcurrent protection device fails and fails to enter the protection state;

[0047] Isolation protection: The circuit breaker switch is in the disconnected state, successfully isolating the overcurrent fault.

[0048] Preferably, a signal monitoring device is added to the constructed overcurrent protection model, and when an overcurrent signal, a timing completion signal, a timing interruption signal, a device abnormality signal or a device action signal is received, the model starts to act;

[0049] The overcurrent signal includes when the current monitored exceeds 1.5 times the rated current, the protection device of the three-stage generator switches from normal operation to standby observation;

[0050] The timing completion signal includes that the timing of the waiting time observation stage is completely completed, the overcurrent signal has not disappeared, and the preset allowable overcurrent existence time is exceeded, and the protection device operating state is switched from waiting time observation to imminent processing;

[0051] The timing interruption signal includes the disappearance of the overcurrent signal, the timing interruption, and the preset allowable existence time is not exceeded, and the working condition of the protection device is switched from waiting observation to normal operation;

[0052] The device abnormality signal includes a fault in the overcurrent protection device, inability to process the overcurrent fault, and the protection device operating state switching from about to be processed to device abnormality;

[0053] The device action signal includes that the overcurrent protection device has not failed, the processing of the overcurrent fault has been completed, and the working state of the protection device has been switched from processing to isolation protection.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] 1. The present invention models the starting and generating process of the three-stage generator based on its structural characteristics and finite state machine theory. By analyzing its various working stages and the conditions required for stage transitions, the present invention realizes the control of all stages in the entire starting and generating process.

[0056] 2. The present invention builds a protection device for the overcurrent fault that is very likely to occur during the no-load boost process of the generator, and uses the overcurrent signal as the condition for the protection device to operate, so that the overcurrent fault can be quickly and efficiently detected and isolated.

[0057] 3. The present invention sets a maximum overcurrent permissible time while building a protection device. If the overcurrent signal can be eliminated in time, the isolation measure will not be initiated, thus avoiding repeated switching to affect the normal operation of the three-stage generator, and has good practicality.

[0058] Other beneficial effects of the present invention will be explained in the specific implementation manner through the introduction of specific technical features and technical solutions. Through the introduction of these technical features and technical solutions, those skilled in the art should be able to understand the beneficial technical effects brought about by the technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0060] Figure 1 It is an integrated block diagram of the three-stage generator starting and generating system in the present invention.

[0061] Figure 2 It is a schematic diagram of the structure of each state and switching process of the finite state machine model in the present invention.

[0062] Figure 3 This is a working phase switching diagram of the three-stage generator starting process using the finite state machine theory in the present invention.

[0063] Figure 4 This is a schematic diagram of the overcurrent protection principle using the finite state machine theory in the present invention.

[0064] Figure 5 This is an action diagram of the overcurrent protection device when receiving an overcurrent signal in the present invention.

[0065] Figure 6 This is a diagram showing the changes in the working stages of the starting and generating process of the three-stage generator in the present invention.

[0066] Figure 7 It is a current curve diagram of the three-stage generator of the present invention during the starting and generating process.

[0067] Figure 8The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0068] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0069] The present invention provides a method for controlling the starting and generating process of a three-stage generator by using finite state machine theory, dividing the starting and generating process into five working modes, monitoring the working state of each mode, and entering the next working mode when the switching condition is met; establishing an overcurrent protection device, monitoring the current and processing in real time according to the monitoring signal, and effectively ensuring the normal operation of the motor.

[0070] The three-stage generator includes three coaxially connected motors, one permanent magnet synchronous motor and two electrically excited synchronous motors. The electrically excited synchronous generator is divided into an auxiliary exciter and a main generator according to its function.

[0071] The starting and generating switching control mainly realizes the on and off control of the external excitation source of the auxiliary exciter through the circuit breaker. In the starting stage, the auxiliary exciter is used as a motor, and the rotor rotates through the external excitation source. The external excitation is disconnected and the power generation stage is switched. At this time, the coaxial rotor rotates with inertia, so that the magnetic flux lines of the main generator are cut and the electromotive force is induced. After completing the no-load boost and voltage regulation control, the output power quality can meet the requirements of the aircraft power supply load.

[0072] Reference Figure 8 As shown, an overcurrent protection method for the start-up power generation process of a three-stage power generation system includes the following steps:

[0073] Step 1, model the three-stage generator, analyze the process of starting and generating electricity, and divide it into five working stages: starting stage, electric power cut-off stage, no-load boost stage, voltage regulation control stage and power generation operation stage.

[0074] Starting phase: The three-stage generator is connected to the electric power and initially runs at a constant torque. When the motor speed reaches the ignition speed, the motor runs at a constant power.

[0075] Cut off the electric power stage: When the electric power is cut off, the current begins to drop to zero. As the rotor rotates with inertia, the magnetic flux lines of the main generator are cut, and the main generator begins to output electric energy.

[0076] No-load boost stage: The closed-loop damping of the circuit under no-load is very small, and the output voltage will continue to rise.

[0077] Voltage regulation control stage: When the output voltage of the main generator reaches the rated voltage, the filter capacitor and the load are connected at the output end. In this stage, the main generator starts to supply power to the load and regulates the voltage to keep the voltage stable.

[0078] Power generation operation phase: disconnect the voltage regulating load, connect the aircraft power load, and provide stable power supply to the aircraft load.

[0079] Step 2, analyzing the working stage change conditions of the above three-stage generator, the conditions for the changes between these working stages are: reaching the disconnection speed, completing the electric power cut-off, loading filtering and reaching the rated speed. When reaching the disconnection speed, the working condition of the three-stage generator changes from the starting stage to the electric power cut-off stage; when the electric power cut-off is completed, the working condition of the three-stage generator changes from the electric power cut-off stage to the no-load boost stage; when the loading filtering is completed, the working condition of the three-stage generator changes from the no-load boost stage to the voltage regulation control stage; when reaching the rated speed, the working condition of the three-stage generator changes from the voltage regulation control stage to the power generation operation stage.

[0080] Step 3, combining the finite state machine theory, design the overcurrent protection model. The operating conditions of the protection device of the three-level generator are divided into normal operation, waiting observation, upcoming processing, device abnormality and isolation protection.

[0081] Normal operation: The three-stage generator operates under standard working conditions;

[0082] Timely observation: receiving the overcurrent signal, but not processing it immediately, waiting for a certain period of time to observe whether the overcurrent signal disappears;

[0083] About to be processed: When the observation time is up and the over-current signal has not disappeared, it is ready to enter the isolation protection stage;

[0084] Device abnormality: Failure to enter the protection state due to a fault in the device isolating the overcurrent protection;

[0085] Isolation protection: The circuit breaker switch is in the disconnected state, successfully isolating the overcurrent fault.

[0086] Step 4, adding a signal monitoring device to the overcurrent protection model, the protection model starts to act when receiving the following five types of signals: overcurrent signal, timing completion signal, timing interruption signal, device abnormality signal, and device action signal.

[0087] Overcurrent signal: When the monitored current exceeds 1.5 times the rated current, the protection device of the three-stage generator switches from normal operation to standby observation;

[0088] Timing completion signal: When the timing of the waiting observation phase is completely completed, the overcurrent signal has not disappeared, and the preset allowable overcurrent existence time is exceeded, the protection device operating state is switched from waiting observation to imminent processing;

[0089] Timing interrupt signal: the overcurrent signal disappears, the timing is interrupted, and the preset allowable existence time is not exceeded. The operating condition of the protection device is switched from waiting observation to normal operation;

[0090] Device abnormal signal: The overcurrent protection device fails and cannot process the overcurrent fault. The protection device operating state switches from processing to device abnormality.

[0091] Device action signal: The overcurrent protection device has not failed and has completed the processing of the overcurrent fault. The operating state of the protection device has been switched from processing to isolation protection.

[0092] The present invention models the starting and generating process of the three-stage generator based on its structural characteristics and finite state machine theory, analyzes its various working stages and the conditions required for stage transition, and realizes the control of all stages in the entire starting and generating process. In view of the overcurrent fault that is very easy to occur during the no-load boosting process, a protection device is made, and the overcurrent signal is used as the condition for the action of the protection device, which can quickly and efficiently monitor the overcurrent fault and isolate it. At the same time, a maximum overcurrent allowable time is set. If the overcurrent signal can be eliminated in time, the isolation measure will not be started, so as to avoid repeated switching affecting the normal operation of the three-stage generator.

[0093] The above is a basic embodiment of the present invention. The technical solution of the present invention is further described below through a preferred embodiment.

[0094] Example 1

[0095] The present invention designs an overcurrent protection method for the starting and generating process of a three-stage generator, and the integrated block diagram of the starting and generating system is as follows: Figure 1 This control method is based on the finite state machine theory. Figure 2 It is a schematic diagram of the structure of each state and switching process of the finite state machine model, which is divided into two elements: "state" and "state switching". S is a finite state set, S = (s1, s2, s3…s n ); F is a finite set of state transition conditions, F = (e1, e2, e3…e n ); output function g i (t,x,x′)=0 is the differential and difference equation used to describe the continuous dynamic process, where the state variable is represented by x and the time variable is represented by t. This method is to decide whether to change its current operating function by observing whether the state variable of the controlled object reaches the switching condition. The specific steps are as follows:

[0096] Step 1, model the three-stage generator, analyze the working process of the starting and generating process, and divide it into five working stages: starting stage, electric power cut-off stage, no-load boost stage, voltage regulation control stage and generating operation stage, such as Figure 3 shown.

[0097] Starting phase: The three-stage generator is connected to the electric power and initially runs at a constant torque. When the motor speed reaches the ignition speed, the motor runs at a constant power.

[0098] Cut off the electric power stage: When the electric power is cut off, the current begins to drop to zero. As the rotor rotates with inertia, the magnetic flux lines of the main generator are cut, and the main generator begins to output electric energy.

[0099] No-load boost stage: The closed-loop damping of the circuit under no-load is very small, and the output voltage will continue to rise.

[0100] Voltage regulation control stage: When the output voltage of the main generator reaches the rated voltage, the filter capacitor and the load are connected at the output end. In this stage, the main generator starts to supply power to the load and regulates the voltage to keep the voltage stable.

[0101] Power generation operation phase: disconnect the voltage regulating load, connect the aircraft power load, and provide stable power supply to the aircraft load.

[0102] Step 2, analyzing the working stage change conditions of the above three-stage generator, the conditions for the changes between these working stages are: reaching the disconnection speed, completing the electric power cut-off, loading filtering and reaching the rated speed. When reaching the disconnection speed, the working condition of the three-stage generator changes from the starting stage to the electric power cut-off stage; when the electric power cut-off is completed, the working condition of the three-stage generator changes from the electric power cut-off stage to the no-load boost stage; when the loading filtering is completed, the working condition of the three-stage generator changes from the no-load boost stage to the voltage regulation control stage; when reaching the rated speed, the working condition of the three-stage generator changes from the voltage regulation control stage to the power generation operation stage.

[0103] Step 3, combining the finite state machine theory, design the overcurrent protection model. The three-level generator protection device operating conditions are divided into normal operation, waiting observation, upcoming processing, device abnormality and isolation protection, such as Figure 4 shown.

[0104] Normal operation: The three-stage generator operates under standard working conditions;

[0105] Timely observation: receiving the overcurrent signal, but not processing it immediately, waiting for a certain period of time to observe whether the overcurrent signal disappears;

[0106] About to be processed: When the observation time is up and the over-current signal has not disappeared, it is ready to enter the isolation protection stage;

[0107] Device abnormality: Failure to enter the protection state due to a fault in the device isolating the overcurrent protection;

[0108] Isolation protection: The circuit breaker switch is in the disconnected state, successfully isolating the overcurrent fault.

[0109] Step 4, adding a signal monitoring device to the overcurrent protection model, the protection model starts to act when receiving the following five types of signals: overcurrent signal, timing completion signal, timing interruption signal, device abnormality signal, and device action signal.

[0110] Overcurrent signal: When the monitored current exceeds 1.5 times the rated current, the protection device of the three-stage generator switches from normal operation to standby observation;

[0111] Timing completion signal: When the timing of the waiting observation phase is completely completed, the overcurrent signal has not disappeared, and the preset allowable overcurrent existence time is exceeded, the protection device operating state is switched from waiting observation to imminent processing;

[0112] Timing interrupt signal: the overcurrent signal disappears, the timing is interrupted, and the preset allowable existence time is not exceeded. The operating condition of the protection device is switched from waiting observation to normal operation;

[0113] Device abnormal signal: The overcurrent protection device fails and cannot process the overcurrent fault. The protection device operating state switches from processing to device abnormality.

[0114] Device action signal: The overcurrent protection device has not failed and has completed the processing of the overcurrent fault. The operating state of the protection device has been switched from processing to isolation protection.

[0115] The above is the overcurrent protection method used in the starting and switching process of the three-stage generator. It completes two functions: one is to realize the switching of the three-stage generator from the starting process to the power generation process, and the change of the working state of the motor from the motor to the generator. The second is to monitor the current signal in real time and isolate it in time to play an overcurrent protection role in view of the current mutation that is easy to cause in the no-load boost process and cause circuit damage.

[0116] The present invention provides a method for controlling the starting and generating process of a three-stage generator by using finite state machine theory, establishes an overcurrent protection device, monitors the current and processes the current in real time according to the monitoring signal, and effectively ensures the normal operation of the motor without damage.

[0117] In order to verify the effectiveness of this method, it is applied to the starting and power generation process control of an aviation three-stage generator. Figure 5As shown in the figure, the overcurrent in the no-load boost process is used as a signal, and a simulation test is performed based on the signal. A three-phase fault module is used to simulate the overcurrent fault condition. Figure 5 (a) is a simulation diagram of the overcurrent signal. The overcurrent signal is issued at 0.5s and disappears after 0.05s. The three-stage generator operates normally. In order to verify the effectiveness of the observation module, the overcurrent signal appears again at 1.5s and remains there. In the figure, when the value of the ordinate is "1", it means there is an overcurrent signal, and when it is "0", it means the overcurrent signal disappears. Through the comparison module, whether the current current is greater than 1.5 times the rated current is determined to determine whether to issue an overcurrent signal. Figure 5 (b) is a normal operation diagram of a three-stage generator. When the value of the vertical axis in the diagram is "1", it indicates normal operation, and when it is "0", it indicates an abnormal state. Figure 5 (c) is a timing observation diagram of a three-stage generator. When the value of the ordinate is "1", it indicates that it is in the timing process, and when it is "0", it indicates that it is not in the timing process. Figure 5 (d) is a diagram of a three-stage generator about to process a signal. When the value of the vertical axis in the diagram is "1", it means that the generator is ready to process an overcurrent fault. Figure 5 (e) is the abnormal diagram of the three-stage generator protection device. When the overcurrent fault is about to be processed, the vertical axis in the diagram is still "0", indicating that the protection device cannot respond to the overcurrent fault. Figure 5 (f) is a three-stage generator isolation protection diagram, where the vertical axis value "1" indicates successful entry into the isolation protection stage.

[0118] like Figure 5 As shown in (b), the overcurrent fault is simulated at 0.5s and 1.5s. The fault is simulated by short-circuiting phase A of the three-phase fault module. The short circuit causes the current to rise sharply, exceeding 1.5 times the rated current. When the first overcurrent signal appears, the overcurrent signal automatically disappears within the set waiting time, causing the current to return to normal levels, and the protection device condition also resumes normal operation. Due to the inherent delay of the three-phase fault module, the overcurrent fault that should have occurred at 0.5s did not occur until 0.512s, so the overcurrent signal was also detected at 0.512s. Therefore, Figure 5 As shown in (c), at 0.512s, the protection device changed from normal operation to standby observation. After 0.055s, the overcurrent signal disappeared and the maximum allowable overcurrent time was not reached. Figure 5 (b) It can be seen that at 0.567s, the protection device returned to normal operation. At 1.5s, the overcurrent signal fault occurred again and persisted. The protection device entered the normal operation state at 1.512s, and after reaching the maximum allowable overcurrent time, the current still exceeded 1.5 times the rated current. Figure 5(d) At 1.613s, the protection device operating condition changes from waiting observation to processing, and the protection device is ready to process the overcurrent fault. Figure 5 As shown in (e), when the overcurrent fault signal is sent, the protection device cannot respond and cannot isolate the fault successfully. Figure 5 As shown in (f), when an overcurrent fault signal is issued, the protection device changes from the overcurrent fault state to the isolation protection state, disconnecting the circuit breaker switch to prevent the three-stage generator from overheating and damage.

[0119] According to the finite state machine theory, the simulation results of the starting and generating process of the three-stage generator are analyzed. Figure 6 The figure shows the working phase changes of the three-stage generator starting and generating process. Figure 6 (a) is the starting stage of the three-stage generator. In the figure, the three-stage generator reaches the disengagement speed at 0.1s. Figure 6 (b) is the stage of cutting off the electric power of the three-stage generator. After receiving the electric power cutting-off signal, the external excitation source of the auxiliary exciter is cut off, the auxiliary exciter exits the motor mode, and the current drops to zero. Figure 6 (c) The three-stage generator adjusts the output voltage to the frequency and amplitude required by the aircraft load during the no-load boost and voltage-regulating load and filter capacitor connection stages. Figure 6 (d) The output voltage reaches the rated voltage, and the three-stage generator enters the power generation operation stage and the speed becomes the rated power generation speed. Figure 7 The current variation curves of the three-stage generator during starting and generating are provided. Figure 7 It can be seen that at 0.1s, the electric power is cut off and the external excitation source is disconnected, and the current first drops to zero. Then at 0.2s, the rotor continues to rotate according to inertia, cutting the magnetic flux lines of the main generator and entering the no-load boost stage. After load voltage regulation, the output power meets the aircraft load power supply requirements and enters the steady-state power generation stage.

[0120] The present invention also provides an overcurrent protection system for the starting and generating process of a three-stage power generation system. The overcurrent protection system for the starting and generating process of the three-stage power generation system can be implemented by executing the process steps of the overcurrent protection method for the starting and generating process of the three-stage power generation system, that is, those skilled in the art can understand the overcurrent protection method for the starting and generating process of the three-stage power generation system as a preferred implementation of the overcurrent protection system for the starting and generating process of the three-stage power generation system.

[0121] Specifically, an overcurrent protection system for starting a power generation process of a three-stage power generation system includes:

[0122] Modeling and division module: Model the three-stage generator and divide the process of starting and generating electricity into different stages;

[0123] Monitoring and isolation module: Use the built overcurrent protection device to monitor the working parameters at different stages, and complete the isolation of overcurrent faults based on the monitoring results.

[0124] The three-stage generator includes three coaxially connected motors, namely a permanent magnet synchronous motor and two electrically excited synchronous motors; the electrically excited synchronous motor includes an auxiliary exciter and a main generator.

[0125] The different stages of starting the generator work are divided into:

[0126] Starting stage: The three-stage generator is connected to the electric power and initially runs at a constant torque. When the motor speed reaches the ignition speed, the motor runs at a constant power.

[0127] Electric power cut-off stage: Electric power is cut off, the current gradually drops to zero, and the main generator starts to output electric energy;

[0128] No-load boost stage: the output voltage continues to rise under no-load;

[0129] Voltage regulation control stage: When the output voltage of the main generator reaches the rated voltage, the filter capacitor and the load are connected at the output end; the main generator starts to supply power to the load and regulates the voltage to keep the voltage stable;

[0130] Power generation operation stage: disconnect the voltage regulating load, connect the aircraft power load, and provide stable power supply to the aircraft load;

[0131] When a certain stage meets the switching conditions, it enters the next working stage; the switching conditions include reaching the disengagement speed, completing the electric power cut-off, loading filtering and reaching the rated speed.

[0132] When the disengagement speed is reached, the operating condition of the three-stage generator changes from the starting stage to the electric power cut-off stage; when the electric power cut-off is completed, the operating condition of the three-stage generator changes from the electric power cut-off stage to the no-load boost stage; when the loading filtering is completed, the operating condition of the three-stage generator changes from the no-load boost stage to the voltage regulation control stage; when the rated speed is reached, the operating condition of the three-stage generator changes from the voltage regulation control stage to the power generation operation stage.

[0133] The overcurrent protection device can remove the fault through the circuit breaker within a limited time; the working conditions of the overcurrent protection device include:

[0134] Normal operation: At this time, the three-stage generator operates under the preset working conditions;

[0135] Observation at a certain time: when receiving an overcurrent signal, wait for a certain period of time to observe whether the overcurrent signal disappears;

[0136] To be processed: If the overcurrent signal does not disappear after the observation time, it is ready to enter the isolation protection stage;

[0137] Device abnormality: At this time, the overcurrent protection device fails and fails to enter the protection state;

[0138] Isolation protection: The circuit breaker switch is in the disconnected state, successfully isolating the overcurrent fault.

[0139] A signal monitoring device is added to the constructed overcurrent protection model, and when an overcurrent signal, a timing completion signal, a timing interruption signal, a device abnormality signal or a device action signal is received, the model starts to act;

[0140] The overcurrent signal includes when the current monitored exceeds 1.5 times the rated current, the protection device of the three-stage generator switches from normal operation to standby observation;

[0141] The timing completion signal includes that the timing of the waiting time observation stage is completely completed, the overcurrent signal has not disappeared, and the preset allowable overcurrent existence time is exceeded, and the protection device operating state is switched from waiting time observation to imminent processing;

[0142] The timing interruption signal includes the disappearance of the overcurrent signal, the timing interruption, and the preset allowable existence time is not exceeded, and the working condition of the protection device is switched from waiting observation to normal operation;

[0143] The device abnormality signal includes a fault in the overcurrent protection device, inability to process the overcurrent fault, and the protection device operating state switching from about to be processed to device abnormality;

[0144] The device action signal includes that the overcurrent protection device has not failed, the processing of the overcurrent fault has been completed, and the working state of the protection device has been switched from processing to isolation protection.

[0145] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0146] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An overcurrent protection method for the start-up power generation process of a three-stage power generation system, characterized in that: include: Modeling division steps: Model the three-stage generator and divide the process of starting and generating electricity into different stages; Monitoring and isolation steps: Use the constructed overcurrent protection device to monitor the working parameters at different stages, and complete the isolation of the overcurrent fault based on the monitoring results.

2. The overcurrent protection method for the start-up power generation process of the three-stage power generation system according to claim 1 is characterized in that: The three-stage generator includes three coaxially connected motors, namely a permanent magnet synchronous motor and two electrically excited synchronous motors; the electrically excited synchronous motor includes an auxiliary exciter and a main generator.

3. The overcurrent protection method for the start-up power generation process of the three-stage power generation system according to claim 2 is characterized in that: The different stages of starting the generator work are divided into: Starting stage: The three-stage generator is connected to the electric power and initially runs at a constant torque. When the motor speed reaches the ignition speed, the motor runs at a constant power. Electric power cut-off stage: Electric power is cut off, the current gradually drops to zero, and the main generator starts to output electric energy; No-load boost stage: the output voltage continues to rise under no-load; Voltage regulation control stage: When the output voltage of the main generator reaches the rated voltage, the filter capacitor and the load are connected at the output end; the main generator starts to supply power to the load and regulates the voltage to keep the voltage stable; Power generation operation stage: disconnect the voltage regulating load, connect the aircraft power load, and provide stable power supply to the aircraft load; When a certain stage meets the switching conditions, it enters the next working stage; the switching conditions include reaching the disengagement speed, completing the electric power cut-off, loading filtering and reaching the rated speed.

4. The overcurrent protection method for the start-up power generation process of the three-stage power generation system according to claim 3 is characterized in that: When the disengagement speed is reached, the operating condition of the three-stage generator changes from the starting stage to the electric power cut-off stage; when the electric power cut-off is completed, the operating condition of the three-stage generator changes from the electric power cut-off stage to the no-load boost stage; when the loading filtering is completed, the operating condition of the three-stage generator changes from the no-load boost stage to the voltage regulation control stage; when the rated speed is reached, the operating condition of the three-stage generator changes from the voltage regulation control stage to the power generation operation stage.

5. The overcurrent protection method for the start-up power generation process of the three-stage power generation system according to claim 1 is characterized in that: The overcurrent protection device can remove the fault through the circuit breaker within a limited time; the working conditions of the overcurrent protection device include: Normal operation: At this time, the three-stage generator operates under the preset working conditions; Observation at a certain time: when receiving an overcurrent signal, wait for a certain period of time to observe whether the overcurrent signal disappears; To be processed: If the overcurrent signal does not disappear after the observation time, it is ready to enter the isolation protection stage; Device abnormality: At this time, the overcurrent protection device fails and fails to enter the protection state; Isolation protection: The circuit breaker switch is in the disconnected state, successfully isolating the overcurrent fault.

6. The overcurrent protection method for the start-up power generation process of the three-stage power generation system according to claim 5 is characterized in that: A signal monitoring device is added to the constructed overcurrent protection model, and when an overcurrent signal, a timing completion signal, a timing interruption signal, a device abnormality signal or a device action signal is received, the model starts to act; The overcurrent signal includes when the current monitored exceeds 1.5 times the rated current, the protection device of the three-stage generator switches from normal operation to standby observation; The timing completion signal includes that the timing of the waiting time observation stage is completely completed, the overcurrent signal has not disappeared, and the preset allowable overcurrent existence time is exceeded, and the protection device operating state is switched from waiting time observation to imminent processing; The timing interruption signal includes the disappearance of the overcurrent signal, the timing interruption, and the preset allowable existence time is not exceeded, and the working condition of the protection device is switched from waiting observation to normal operation; The device abnormality signal includes a fault in the overcurrent protection device, inability to process the overcurrent fault, and the protection device operating state is switched from being processed to device abnormality; The device action signal includes that the overcurrent protection device has not failed, the processing of the overcurrent fault has been completed, and the working state of the protection device has been switched from processing to isolation protection.

7. An overcurrent protection system for the start-up power generation process of a three-stage power generation system, characterized in that: include: Modeling and division module: Model the three-stage generator and divide the process of starting and generating electricity into different stages; Monitoring and isolation module: Use the built overcurrent protection device to monitor the working parameters at different stages, and complete the isolation of overcurrent faults based on the monitoring results.

8. The overcurrent protection system for the start-up power generation process of the three-stage power generation system according to claim 7 is characterized in that: The three-stage generator includes three coaxially connected motors, namely a permanent magnet synchronous motor and two electrically excited synchronous motors; the electrically excited synchronous motor includes an auxiliary exciter and a main generator.

9. The overcurrent protection system for the start-up power generation process of the three-stage power generation system according to claim 8, characterized in that: The different stages of starting the generator work are divided into: Starting stage: The three-stage generator is connected to the electric power and initially runs at a constant torque. When the motor speed reaches the ignition speed, the motor runs at a constant power. Electric power cut-off stage: Electric power is cut off, the current gradually drops to zero, and the main generator starts to output electric energy; No-load boost stage: the output voltage continues to rise under no-load; Voltage regulation control stage: When the output voltage of the main generator reaches the rated voltage, the filter capacitor and the load are connected at the output end; the main generator starts to supply power to the load and regulates the voltage to keep the voltage stable; Power generation operation stage: disconnect the voltage regulating load, connect the aircraft power load, and provide stable power supply to the aircraft load; When a certain stage meets the switching conditions, it enters the next working stage; the switching conditions include reaching the disengagement speed, completing the electric power cut-off, loading filtering and reaching the rated speed.

10. The overcurrent protection system for the start-up power generation process of the three-stage power generation system according to claim 9, characterized in that: When the disengagement speed is reached, the operating condition of the three-stage generator changes from the starting stage to the electric power cut-off stage; when the electric power cut-off is completed, the operating condition of the three-stage generator changes from the electric power cut-off stage to the no-load boost stage; when the loading filtering is completed, the operating condition of the three-stage generator changes from the no-load boost stage to the voltage regulation control stage; when the rated speed is reached, the operating condition of the three-stage generator changes from the voltage regulation control stage to the power generation operation stage.

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