Starting control system and method for air-cooled static frequency converter of pumped storage unit

Abstract

The invention discloses a start control system and control method for an air-cooled static frequency converter of a pumped storage unit, and the system achieves the precise control of multiple parameters in the starting process of the pumped storage unit through the combined use of the static frequency converter, a cooling fan, a control unit and a control module. The input end of the static frequency converter is connected with a power system and directly acts on a stator winding of the synchronous motor through the output end, stator current and exciting current of the motor are controlled in a low-frequency pulse mode, and stable starting is ensured. The cooling fan is connected with a main loop assembly of the SFC, the temperature is effectively controlled through an air circulation cooling system, and the system is prevented from being overheated. The control unit coordinates all devices in the whole starting and stopping process, and the synchronous motor is smoothly switched to normal synchronous operation from a low-frequency pulse starting mode.

Description

Technical Field

[0001] The present invention belongs to the field of static frequency converter starting control, and in particular, relates to a pumped storage unit air-cooled static frequency converter starting control system and control method. Background Art

[0002] As an indispensable energy storage and regulation device in the power system, pumped storage units play an important role in peak regulation, valley filling, frequency regulation and phase regulation of the power grid. However, the startup process of the unit is extremely complex, involving the coordination of multiple systems and equipment. Traditional startup methods usually have the following problems: low efficiency, long startup time, large current impact during startup, resulting in excessive wear of the motor and related components. At the same time, the system generates a lot of heat during the startup phase. If the cooling system does not respond in time or is improperly controlled, the temperature of the heating element may rise sharply, causing the equipment to overheat or even damage. Especially in the startup process of synchronous motors, due to their structural characteristics, the stator current and excitation current need to be precisely controlled to achieve stable low-frequency startup. If the current is not properly controlled, it is easy to cause current overshoot, motor loss of step and other problems, which seriously affect the stability and safety of the startup. In addition, temperature management is also a key factor in the startup process. The heating element is prone to generate too much heat under high load. If the heat is not effectively dissipated, it will further affect the operating efficiency and life of the motor.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a pumped storage unit air-cooled static inverter startup control system and control method, which solves the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0006] A pumped storage unit air-cooled static inverter start-up control system, comprising: a static inverter, a synchronous motor, a cooling fan, a bypass switch, a main circuit switch, a control unit, a main circuit component, and a control module;

[0007] The input end of the static frequency converter is connected to the power system power bus through the input switch, and the output end is connected to the stator winding of the synchronous motor through the output switch. It is used to control the low-frequency starting of the synchronous motor, and control the stator current and excitation current of the synchronous motor to achieve low-frequency pulsating starting, and switch to the normal synchronous operation mode through the main circuit switch;

[0008] The cooling fan is connected to the main circuit components of the SFC through a pipeline and is used to circulate air to cool these heating elements;

[0009] The control unit is connected to the static inverter, bypass switch, main circuit switch and cooling system through signal lines to coordinate and control various devices during the start and stop process;

[0010] The control module is connected to the static inverter, cooling system, and control unit through data transmission lines. It is used to create a virtual model of the SFC system and perform interactive simulations with real-time and historical data to optimize the adjustment of various parameters during the unit startup process.

[0011] Optionally, the steps for low-frequency starting of a synchronous motor controlled by a static frequency converter are:

[0012] The static inverter first starts to output low-frequency pulsating current to control the stator current and excitation current of the synchronous motor. As the pulsating current gradually increases, the static inverter gradually increases the torque of the synchronous motor, generating an unbalanced torque, thereby driving the synchronous motor to start slowly.

[0013] During this low-frequency starting phase, the bypass switch is closed, so that the output current of the static inverter directly acts on the stator winding of the synchronous motor, thereby further accelerating the motor through pulsating operation;

[0014] As the speed of the synchronous motor gradually increases, when it reaches the predetermined speed, the motor enters the synchronous motor drive mode, and the pulsating operation mode ends. When the speed of the synchronous motor reaches 10% of the rated speed, the control unit issues a command to cut off the bypass switch and close the main circuit switch;

[0015] After the main circuit breaker is closed, the motor switches from the low-frequency pulsating operation mode to the normal three-phase rotating magnetic field operation, and the motor enters a stable synchronous operation state. After that, the motor continues to accelerate in the synchronous drag mode until it reaches the rated speed;

[0016] When the motor reaches the rated speed, the static inverter gradually exits operation and the motor switches to being directly powered by the power grid, completing the entire startup process.

[0017] Optionally, the steps of the cooling fan performing air circulation cooling on the heating element are:

[0018] Before the static inverter is started, the control unit first detects the operating status of the cooling fan, and after confirming that the cooling system is normal, it sends a start signal and the cooling fan starts to run. The cooling fan is connected to the main circuit component of the SFC through a pipeline to form an air circulation cooling channel to provide continuous cooling for the heating elements in the main circuit;

[0019] After the cooling fan is started, cold air is continuously delivered to the heating element area of ​​the SFC through the pipe. After absorbing the heat generated by the heating element, the air is discharged to the outside through the circulation system to reduce the temperature of the main circuit components.

[0020] During the cooling process, the temperature sensor monitors the temperature change of the SFC main circuit in real time and feeds the temperature back to the control unit. Based on the fed-back temperature data, the cooling fan will automatically adjust the wind speed and cooling intensity to provide sufficient cooling support at each stage of SFC startup and motor acceleration.

[0021] After the motor is started and switched to direct power supply from the grid, the cooling fan will continue to run for a period of time to ensure that the temperature of the main circuit components gradually drops to a safe level. Finally, the control unit issues a command based on the real-time monitoring results of the temperature sensor to stop the operation of the cooling fan.

[0022] Optionally, the temperature sensor monitors the temperature change of the SFC main circuit in real time and feeds back the temperature to the control unit. According to the fed-back temperature data, the cooling fan automatically adjusts the wind speed and cooling intensity in the following steps:

[0023] Temperature sensors are installed in the key heating element areas of the main circuit components to monitor the temperature changes in these areas in real time. The temperature sensors will continuously collect temperature data of the heating elements in the main circuit;

[0024] The temperature sensor transmits the collected temperature data of the SFC main circuit heating element area to the control unit in real time. The control unit presets the temperature threshold. Then, after receiving the temperature data, the received temperature data is compared with the preset temperature threshold of the system, and the corresponding adjustment instructions are generated according to the threshold comparison result and sent to the cooling fan through the signal line, instructing it to increase or decrease the wind speed and cooling intensity.

[0025] Optionally, when the control unit sends an adjustment instruction, if it detects that the temperature rises, the control unit will increase the wind speed or cooling intensity of the cooling fan; if the temperature drops to a normal range, the cooling fan will reduce the wind speed or intensity.

[0026] Optionally, the control unit can also analyze the temperature change trend over a period of time by a linear regression algorithm, the steps of which are:

[0027] Continuously collect and store real-time data from the temperature sensor, then select the time window for regression analysis, determine the amount of data used to fit the linear regression model, then use the temperature data as the dependent variable Y, time as the independent variable X, and fit a straight line through the linear regression algorithm to describe the temperature change trend over the past period of time. The linear regression equation is expressed as Y=β0+β1, where Y is the temperature value, X is the time, β0 is the intercept, and β1 is the rate of change of time and temperature. Then, the slope β1 is calculated through the fitted regression line, which represents the rate of change of temperature per unit time, and is expressed as: X i It's time, Y i is the corresponding temperature, and They are the average values ​​of time and temperature respectively. According to the positive or negative value of the slope β1, it is predicted whether the temperature will rise or fall. If the slope is positive, it means that the temperature is rising; if the slope is negative, it means that the temperature is falling.

[0028] Optionally, the control module obtains data from the system in real time, including the status data of the static inverter, the temperature data of the cooling system, and the operation instructions issued by the control unit. In addition to receiving real-time data, the control module also stores the historical data of the past operation of the SFC system. Then, based on the collected real-time data and historical data, the control module creates a virtual model of the SFC system to simulate the system operation effect under different parameter settings. Subsequently, through the virtual model, the control module performs interactive simulation of real-time data and historical data. Then, the control module compares the currently collected real-time data with the historical data in the virtual model to predict possible future situations. Finally, according to the current real-time load and the feedback of the virtual model, the current parameters are dynamically optimized to make the current change smooth during the motor startup process;

[0029] In addition, the control module can dynamically adjust the switching timing of the bypass switch and the main circuit switch according to the optimal switching point fed back by the virtual model, so that the system can complete the switch switching at the appropriate time.

[0030] Optionally, the steps for creating a virtual model of the SFC system are:

[0031] First, historical data combined with deep neural networks are used to establish and train machine learning models, so that the machine learning model can understand the changing patterns of different parameters at startup and the relationship between the parameters. Then, physical models of the components of the system are established. The static inverter model can describe the relationship between current, voltage and torque based on circuit theory and power equations, where the formula Calculate the output current I(t) of the static inverter, where V(t) is the voltage at time t and Z(t) is the impedance. Then, for the synchronous motor model, use the mechanical equations and electromagnetic formulas to describe the dynamic response of the motor, including the stator current I s The relationship between speed ω(t) and torque T(t) is expressed as: T(t) = k m I s (t)·ω(t), where k m is the motor constant, the cooling system is simulated by the heat conduction equation, and the wind speed v of the cooling fan f The relationship between (t) and the temperature drop rate ΔT(t) is: ΔT(t) = α·v f (t)-β·P(t), where α and β are system constants and P(t) is the heat load of the system;

[0032] Next, the coupling between components is simulated. The static inverter, synchronous motor and cooling system interact with each other. As the synchronous motor speed ω(t) increases, the cooling fan speed v f (t) needs to be adjusted dynamically to maintain a suitable temperature. The expression of its coupling relationship is: f (t) = f(ω(t), T(t)). Then, when creating a virtual model, the physical model is combined with the machine learning model. The real-time data of the system is collected through the data transmission line, and the data is input into the virtual model for simulation. The model can predict the future state of the system and identify potential current overshoot or overtemperature problems based on the prediction results of physical rules and historical data. The expression is: I pred (t) = I real (t)+ΔI(t)where I pred (t) is the predicted current change trend, I real (t) is the current current, ΔI(t) is the current change predicted based on historical data and machine learning, and finally, the parameters during the startup process are continuously adjusted based on real-time feedback. For example, the virtual model dynamically adjusts the current output of the static inverter based on feedback, and its expression is: I(t) = I pred (t)-γ·f b (t), where f b (t) is the feedback error, γ is the adjustment coefficient, and at the same time, the wind speed of the cooling fan is also adjusted according to the temperature feedback to ensure the smooth operation of the system. The main circuit components include high-power thyristors and DC reactors.

[0033] A method for starting and controlling an air-cooled static frequency converter of a pumped storage unit includes starting and controlling the air-cooled static frequency converter and stopping the air-cooled static frequency converter. The method for starting and controlling the air-cooled static frequency converter includes the following steps:

[0034] Step A1: The unit LCU issues a command to open the input / output transformer cooling water electric valve and ensure that the cooling water valve is open;

[0035] Step A2: After receiving the start command, the SFC starts the SFC start operation. If the SFC start fails, the process is terminated. If successful, proceed to the next step.

[0036] Step A3: SFC issues an input / output variable oil pump start command and starts the fan. Then, it determines whether the flow of the input / output variable oil pump is normal. If not, the process terminates. If normal, proceed to the next step.

[0037] Step A4: The fans of the network bridge cabinet, the machine bridge cabinet and the reactor cabinet start running. Then, it is determined whether the fans are running normally. If not, the process is terminated. If the fans are running normally, proceed to the next step.

[0038] Step A5: SFC issues a bypass switch closing command to turn on the bypass switch. Next, it is determined whether the bypass switch is closed successfully. If not, the process is terminated. If successful, the process proceeds to the next step.

[0039] Step A6: SFC monitors the unit frequency and reaches the switching frequency (usually 5 Hz, about 10% of the rated speed of the unit). Then, it is determined whether the unit has reached the target frequency. If not, the process is terminated. If it has reached the target frequency, it proceeds to the next step.

[0040] Step A7: SFC issues a main circuit switch closing command to connect the main circuit, and then determines whether the main circuit switch is closed successfully. If not, the process terminates; if successful, proceed to the next step;

[0041] Step A8: SFC sends an input switch closing request, and the unit LCU selects to close the SFC input switch. Then, it is determined whether the SFC input switch is successfully closed. If not, the process is terminated. If successful, the startup process is completed.

[0042] Step A9: SFC startup is completed and the system runs normally.

[0043] A method for starting and controlling an air-cooled static frequency converter of a pumped storage unit, and a method for stopping and controlling an air-cooled static frequency converter include the following steps:

[0044] Step S1: The unit LCU issues a command to close the outlet switch or perform synchronous closing operation. If the outlet switch closing or synchronous closing signal is successful, proceed to the next step.

[0045] Step S2: The SFC issues an output switch opening command to disconnect the SFC output switch. Next, it is determined whether the SFC output switch is opened successfully. If not, the process terminates; if successful, proceed to the next step.

[0046] Step S3: SFC issues a main circuit switch opening command, and then determines whether the main circuit switch is opened successfully. If not, the process terminates; if successful, proceed to the next step;

[0047] Step S4: SFC issues a blower stop command and an output variable oil pump stop command to shut down the auxiliary equipment. Next, it is determined whether the blower and the output variable oil pump are successfully stopped. If not, the process is terminated; if successful, proceed to the next step.

[0048] Step S5: SFC issues a command to close the input / output transformer cooling water electric valve, and then determines whether the cooling water electric valve is successfully closed. If not, the process terminates; if successful, proceed to the next step;

[0049] Step S6: The SFC system is completely stopped and the process ends.

[0050] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all the advantages described below at the same time:

[0051] This application realizes the precise control of multiple parameters during the startup process of the pumped storage unit by combining a static frequency converter, a cooling fan, a control unit and a control module. The input end of the static frequency converter is connected to the power system, and directly acts on the stator winding of the synchronous motor through the output end, controlling the stator current and excitation current of the motor in a low-frequency pulsation mode to ensure smooth startup. The cooling fan is connected to the main circuit component of the SFC, and the temperature is effectively controlled through the air circulation cooling system to prevent the system from overheating. The control unit coordinates the various devices in the entire start-up and stop process to achieve a smooth switch from the low-frequency pulsation start-up mode to the normal synchronous operation of the synchronous motor. The control module creates a virtual model, combines real-time data and historical data for interactive simulation, and dynamically optimizes the various parameters during the startup process, avoiding current overshoot and temperature anomalies, and improving the reliability and startup efficiency of the system.

[0052] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The drawings described below are only some embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0054] In the figure:

[0055] Figure 1 It is the schematic diagram of the control system circuit;

[0056] Figure 2 The schematic diagram of the startup process of the static frequency converter SFC is shown below;

[0057] Figure 3 The figure is a schematic diagram of the stop process of the static frequency converter SFC.

[0058] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0059] The present invention will now be described in further detail with reference to the accompanying drawings.

[0060] See also Figure 1-3 As shown, in this embodiment, a pumped storage unit air-cooled static inverter starting control system is provided, including a static inverter, a synchronous motor, a cooling fan, a bypass switch, a main circuit switch, a control unit, a main circuit component, and a control module;

[0061] The input end of the static frequency converter is connected to the power system power bus through the input switch, and the output end is connected to the stator winding of the synchronous motor through the output switch. It is used to control the low-frequency starting of the synchronous motor, and control the stator current and excitation current of the synchronous motor to achieve low-frequency pulsating starting, and switch to the normal synchronous operation mode through the main circuit switch;

[0062] The cooling fan is connected to the main circuit components of the SFC through a pipeline and is used to circulate air to cool these heating elements;

[0063] The control unit is connected to the static inverter, bypass switch, main circuit switch and cooling system through signal lines to coordinate and control various devices during the start and stop process;

[0064] The control module is connected to the static inverter, cooling system, and control unit through data transmission lines. It is used to create a virtual model of the SFC system and perform interactive simulations with real-time and historical data to optimize the adjustment of various parameters during the unit startup process.

[0065] In this embodiment, the steps of the static frequency converter controlling the low-frequency starting of the synchronous motor are as follows:

[0066] The static inverter first starts to output low-frequency pulsating current to control the stator current and excitation current of the synchronous motor. As the pulsating current gradually increases, the static inverter gradually increases the torque of the synchronous motor, generates an unbalanced torque, and thus promotes the slow start of the synchronous motor; by gradually increasing the pulsating current, the motor start is smoothly controlled, the current impact during the start process is reduced, and the torque is gradually increased during the start process to ensure the stable start of the synchronous motor. In addition, by switching the bypass switch, a smooth transition from low-frequency start mode to synchronous operation mode is achieved, which improves the start efficiency and safety. When the static inverter starts to output low-frequency pulsating current, the stator current and excitation current gradually increase. However, at the beginning of the start, because the motor speed is still very low, the magnetic field between the stator current and the rotor is not fully synchronized, resulting in an asymmetric torque generated by the interaction between the magnetic fields, which is the so-called "unbalanced torque". This unbalanced torque prompts the motor rotor to gradually overcome the static state and start to rotate slowly.

[0067] As the pulsating current increases, the torque of the motor gradually increases, the rotor starts to rotate at a faster speed, and gradually reaches a certain speed, entering the drag stage of the synchronous motor. In this stage, although the synchronization of the magnetic field and the rotor has not been fully established, the motor can start at a low frequency and accelerate slowly through the action of the unbalanced torque.

[0068] During this low-frequency starting phase, the bypass switch is closed, so that the output current of the static inverter directly acts on the stator winding of the synchronous motor, thereby further accelerating the motor through pulsating operation;

[0069] As the speed of the synchronous motor gradually increases, when it reaches the predetermined speed, the motor enters the synchronous motor drive mode, and the pulsating operation mode ends. When the speed of the synchronous motor reaches 10% of the rated speed, the control unit issues a command to cut off the bypass switch and close the main circuit switch;

[0070] After the main circuit breaker is closed, the motor switches from the low-frequency pulsating operation mode to the normal three-phase rotating magnetic field operation, and the motor enters a stable synchronous operation state. After that, the motor continues to accelerate in the synchronous drag mode until it reaches the rated speed;

[0071] When the motor reaches the rated speed, the static inverter gradually exits operation and the motor switches to being directly powered by the power grid, completing the entire startup process.

[0072] In this embodiment, the steps of the cooling fan performing air circulation cooling on the heating element are as follows:

[0073] Before the static inverter is started, the control unit first detects the operating status of the cooling fan, and after confirming that the cooling system is normal, it sends a start signal and the cooling fan starts to run. The cooling fan is connected to the main circuit component of the SFC through a pipeline to form an air circulation cooling channel to provide continuous cooling for the heating elements in the main circuit;

[0074] After the cooling fan is started, cold air is continuously delivered to the heating element area of ​​the SFC through the pipe. After absorbing the heat generated by the heating element, the air is discharged to the outside through the circulation system to reduce the temperature of the main circuit components.

[0075] During the cooling process, the temperature sensor monitors the temperature change of the SFC main circuit in real time and feeds the temperature back to the control unit. Based on the fed-back temperature data, the cooling fan will automatically adjust the wind speed and cooling intensity to provide sufficient cooling support at each stage of SFC startup and motor acceleration.

[0076] When the motor is started and switched to direct power supply from the grid, the cooling fan will continue to run for a period of time to ensure that the temperature of the main circuit components gradually drops to a safe level. Finally, the control unit issues a command based on the real-time monitoring results of the temperature sensor to stop the operation of the cooling fan. By automatically monitoring and dynamically adjusting the wind speed and intensity of the cooling fan, the system temperature is always kept within a reasonable range during the startup and operation stages to avoid overheating of the heating components. Even after the motor is switched to grid power supply, the cooling fan continues to run for a period of time, effectively preventing system damage caused by temperature accumulation and ensuring the reliability of the entire process.

[0077] In this embodiment, the temperature sensor monitors the temperature change of the SFC main circuit in real time and feeds back the temperature to the control unit. According to the fed-back temperature data, the cooling fan automatically adjusts the wind speed and cooling intensity in the following steps:

[0078] Temperature sensors are installed in the key heating element areas of the main circuit components to monitor the temperature changes in these areas in real time. The temperature sensors will continuously collect temperature data of the heating elements in the main circuit;

[0079] The temperature sensor transmits the collected temperature data of the heating element area of ​​the SFC main circuit to the control unit in real time. The control unit presets the temperature threshold. Then, after receiving the temperature data, it compares the received temperature data with the preset temperature threshold of the system, and generates corresponding adjustment instructions based on the threshold comparison results and sends them to the cooling fan through the signal line, instructing it to increase or decrease the wind speed and cooling intensity. Through real-time monitoring of the temperature sensor, the control system can automatically adjust the working state of the cooling fan and realize automatic temperature control. This process eliminates human intervention, improves the intelligence and automation of the system, ensures the temperature safety of each heating element during startup and operation, and extends the service life of the system.

[0080] In this embodiment, when the control unit sends an adjustment instruction, if it detects that the temperature rises, the control unit will increase the wind speed or cooling intensity of the cooling fan; if the temperature drops to a normal range, the cooling fan will reduce the wind speed or intensity. Based on the real-time temperature data, the control unit can respond quickly and automatically increase or decrease the wind speed and intensity of the cooling fan. This dynamic adjustment mechanism improves the response speed of the system, ensuring that measures can be taken immediately when the temperature changes, avoiding system failures due to temperature out of control.

[0081] In this embodiment, the control unit can also analyze the temperature change trend over a period of time through a linear regression algorithm, and the steps are as follows:

[0082] Continuously collect and store real-time data from the temperature sensor, then select the time window for regression analysis, determine the amount of data used to fit the linear regression model, then use the temperature data as the dependent variable Y, time as the independent variable X, and fit a straight line through the linear regression algorithm to describe the temperature change trend over the past period of time. The linear regression equation is expressed as Y=β0+β1, where Y is the temperature value, X is the time, β0 is the intercept, and β1 is the rate of change of time and temperature. Then, the slope β1 is calculated through the fitted regression line, which represents the rate of change of temperature per unit time, and is expressed as: X i It's time, Y i is the corresponding temperature, and are the average values ​​of time and temperature respectively. According to the positive or negative slope β1, it is predicted whether the temperature will rise or fall. If the slope is positive, it means the temperature is rising; if the slope is negative, it means the temperature is falling. Through the analysis of temperature change trend by linear regression algorithm, the control system can not only monitor the current temperature, but also predict the future temperature trend, so as to make cooling decisions in advance. This prediction capability improves the preventive maintenance effect of the system, ensures that corresponding measures are taken before the temperature reaches the dangerous threshold, and increases the safety and stability of the system.

[0083] In this embodiment, the control module acquires data from the system in real time, including the status data of the static frequency converter, the temperature data of the cooling system, and the operation instructions issued by the control unit. In addition to receiving real-time data, the control module also stores historical data of the past operation of the SFC system, such as the change of current, temperature fluctuation and unit response time during the previous startup process, etc. Then, based on the collected real-time data and historical data, the control module creates a virtual model of the SFC system to simulate the system operation effect under different parameter settings, specifically including the dynamic interaction between components such as the static frequency converter, the cooling system and the synchronous motor. Subsequently, through the virtual model, the control module performs interactive simulation of real-time data and historical data. Then, the control module compares the currently collected real-time data with the historical data in the virtual model, so as to predict possible future situations, such as current shock or temperature anomaly. Finally, according to the current real-time load and the feedback of the virtual model, the current parameters are dynamically optimized to make the current change smooth during the motor startup process.

[0084] In addition, the control module can dynamically adjust the switching timing of the bypass switch and the main circuit switch according to the optimal switching point fed back by the virtual model, so that the system can complete the switch switching at the appropriate time. The virtual model combines real-time data and historical data to simulate the dynamic response of the system more accurately. Through this simulation, the control module can predict the future system status, identify potential current shocks or temperature anomalies in advance, ensure the smooth operation of the system, and reduce potential failure risks.

[0085] In this embodiment, the steps of creating a virtual model of the SFC system are as follows:

[0086] First, historical data combined with deep neural networks are used to establish and train machine learning models, so that the machine learning model can understand the changing patterns of different parameters at startup and the relationship between the parameters. Then, physical models of the components of the system are established. The static inverter model can describe the relationship between current, voltage and torque based on circuit theory and power equations, where the formula Calculate the output current I(t) of the static inverter, where V(t) is the voltage at time t and Z(t) is the impedance. Then, for the synchronous motor model, use the mechanical equations and electromagnetic formulas to describe the dynamic response of the motor, including the stator current I s The relationship between speed ω(t) and torque T(t) is expressed as: T(t) = k m I s (t)·ω(t), where k m is the motor constant, the cooling system is simulated by the heat conduction equation, and the wind speed v of the cooling fan f The relationship between (t) and the temperature drop rate ΔT(t) is: ΔT(t) = α·vf (t)-β·P(t), where α and β are system constants and P(t) is the heat load of the system;

[0087] Next, the coupling between components is simulated. The static inverter, synchronous motor and cooling system interact with each other. As the synchronous motor speed ω(t) increases, the cooling fan speed v f (t) needs to be adjusted dynamically to maintain a suitable temperature. The expression of its coupling relationship is: f (t) = f(ω(t), T(t)). Then, when creating a virtual model, the physical model is combined with the machine learning model. The real-time data of the system is collected through the data transmission line, and the data is input into the virtual model for simulation. The model can predict the future state of the system and identify potential current overshoot or overtemperature problems based on the prediction results of physical rules and historical data. The expression is: I pred (t) = I real (t)+ΔI(t)where I pred (t) is the predicted current change trend, I real (t) is the current current, ΔI(t) is the current change predicted based on historical data and machine learning, and finally, the parameters during the startup process are continuously adjusted based on real-time feedback. For example, the virtual model dynamically adjusts the current output of the static inverter based on feedback, and its expression is: I(t) = I pred (t)-γ·f b (t), where f b (t) is the feedback error, γ is the adjustment coefficient, and the wind speed of the cooling fan is also adjusted according to the temperature feedback to ensure smooth operation of the system. The main circuit components include high-power thyristors and DC reactors. By combining historical data and deep neural networks to establish a virtual model, the system can dynamically simulate the interaction between components during the startup process. This intelligent virtual model can not only simulate the current system operating status, but also optimize the current and cooling parameters based on feedback to ensure optimal system efficiency and stability during the startup process.

[0088] A method for starting and controlling an air-cooled static frequency converter of a pumped storage unit, characterized in that it includes starting and controlling the air-cooled static frequency converter and stopping the air-cooled static frequency converter, wherein the method for starting and controlling the air-cooled static frequency converter includes the following steps:

[0089] Step A1: The unit LCU issues a command to open the input / output transformer cooling water electric valve and ensure that the cooling water valve is open;

[0090] Step A2: After receiving the start command, the SFC starts the SFC start operation. If the SFC start fails, the process is terminated. If successful, proceed to the next step.

[0091] Step A3: SFC issues an input / output variable oil pump start command and starts the fan. Then, it determines whether the flow of the input / output variable oil pump is normal. If not, the process terminates. If normal, proceed to the next step.

[0092] Step A4: The fans of the network bridge cabinet, the machine bridge cabinet and the reactor cabinet start running. Then, it is determined whether the fans are running normally. If not, the process is terminated. If the fans are running normally, proceed to the next step.

[0093] Step A5: SFC issues a bypass switch closing command to turn on the bypass switch. Next, it is determined whether the bypass switch is closed successfully. If not, the process is terminated. If successful, the process proceeds to the next step.

[0094] Step A6: SFC monitors the unit frequency and reaches the switching frequency (usually 5 Hz, about 10% of the rated speed of the unit). Then, it is determined whether the unit has reached the target frequency. If not, the process is terminated. If it has reached the target frequency, it proceeds to the next step.

[0095] Step A7: SFC issues a main circuit switch closing command to connect the main circuit, and then determines whether the main circuit switch is closed successfully. If not, the process terminates; if successful, proceed to the next step;

[0096] Step A8: SFC sends an input switch closing request, and the unit LCU selects to close the SFC input switch. Then, it is determined whether the SFC input switch is successfully closed. If not, the process is terminated. If successful, the startup process is completed.

[0097] Step A9: SFC startup is completed and the system runs normally.

[0098] A method for starting and controlling an air-cooled static frequency converter of a pumped storage unit, and a method for stopping and controlling an air-cooled static frequency converter include the following steps:

[0099] Step S1: The unit LCU issues a command to close the outlet switch or perform synchronous closing operation. If the outlet switch closing or synchronous closing signal is successful, proceed to the next step.

[0100] Step S2: The SFC issues an output switch opening command to disconnect the SFC output switch. Next, it is determined whether the SFC output switch is opened successfully. If not, the process terminates; if successful, proceed to the next step.

[0101] Step S3: SFC issues a main circuit switch opening command, and then determines whether the main circuit switch is opened successfully. If not, the process terminates; if successful, proceed to the next step;

[0102] Step S4: SFC issues a blower stop command and an output variable oil pump stop command to shut down the auxiliary equipment. Next, it is determined whether the blower and the output variable oil pump are successfully stopped. If not, the process is terminated; if successful, proceed to the next step.

[0103] Step S5: SFC issues a command to close the input / output transformer cooling water electric valve, and then determines whether the cooling water electric valve is successfully closed. If not, the process terminates; if successful, proceed to the next step;

[0104] Step S6: The SFC system is completely stopped and the process ends.

[0105] like Figure 1 As shown, the main circuit of the SFC control system is usually controlled by high-power thyristor electronic components. Since the current transmitted in the main circuit is large, usually up to about 2000 amperes, a lot of heat will be generated during operation. If this heat cannot be dissipated in time, it will cause the equipment to overheat, affecting the stability and service life of the system. In order to solve this problem, the SFC control system is usually equipped with two cooling methods: water cooling and air cooling.

[0106] Water-cooled cooling system: Deionized water is used as the cooling medium. Deionized water removes heat from high-power electronic components through a circulation system, especially for cooling core components in the main circuit of the SFC system, such as thyristor components and DC reactors. The advantage of this method is that water has a high thermal conductivity and can quickly remove a large amount of heat, so it is very suitable for use in systems that require high-power and efficient heat dissipation. Water-cooled systems usually require additional water pumps, pipes, and cooling equipment to ensure that deionized water can continue to circulate in the system, and in order to avoid the risk of electrolysis and corrosion, deionized water can effectively reduce the electrochemical impact on the equipment.

[0107] Air-cooled cooling system: uses air as the cooling medium. By installing a high-power cooling fan, cold air is introduced into the SFC control system to perform forced air convection cooling on high-temperature components such as thyristor components and DC reactors. The main features of the air-cooled cooling system are relatively simple structure, easy maintenance and installation, and no need for additional water treatment equipment. Therefore, it is suitable for occasions where the environment is relatively dry and no special water cooling treatment is required. Although the thermal conductivity of air is not as good as that of water, air cooling still has a wide range of application value for some power equipment or working conditions with environmental restrictions.

[0108] Whether it is water cooling or air cooling, their common goal is to ensure the stable operation of the SFC system and prevent the high-power electronic components in the main circuit from overheating and causing system failure or damage. In high-power power control systems, choosing the right cooling method can not only improve the working efficiency of the equipment, but also extend its service life. Figure 1In the diagram, the black box represents the main circuit of the system, which includes the core components of the SFC system, such as high-power thyristor components, DC reactors and other related equipment. Whether it is water-cooled or air-cooled, their cooling targets are concentrated in the part within this "black box".

[0109] Specifically, the main circuit of the SFC system (in the black box) is the key area responsible for converting and regulating electrical energy. It carries the task of transmitting and regulating large currents, so the components in this area tend to generate a lot of heat. In order to ensure that these key components can still work stably under high load operation, the design and selection of the cooling system is crucial. Whether it is deionized water cooling or air circulation cooling, the main circuit components in this black box will be cooled to ensure the normal operation of the system and long-term efficient operation.

[0110] Figure 1 ICB1\ICB2 are the two input switches of the static inverter.

[0111] TLS is the input transformer. One end is connected to the power system power bus through ICB1\ICB2. The other end is directly connected to the main circuit of the static frequency converter SFC (red box).

[0112] TMS is an output transformer. One end is connected to the bypass switch S1 in the static frequency converter SFC (red box), and the other end is connected to the main electrical circuit of the generator motor through the static frequency converter output switch OCB.

[0113] The present invention is not limited to the above-mentioned embodiments. Anyone should be aware that any structural changes made under the enlightenment of the present invention, and any technical solutions that are the same or similar to the present invention, fall within the protection scope of the present invention. The technology, shape, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A pumped storage unit air-cooled static inverter start-up control system, characterized in that: include: Static frequency converter, synchronous motor, cooling fan, bypass switch, main circuit switch, control unit, main circuit components, control module; The input end of the static frequency converter is connected to the power system power bus through the input switch, and the output end is connected to the stator winding of the synchronous motor through the output switch. It is used to control the low-frequency starting of the synchronous motor, and control the stator current and excitation current of the synchronous motor to achieve low-frequency pulsating starting, and switch to the normal synchronous operation mode through the main circuit switch; The cooling fan is connected to the main circuit components of the SFC through a pipeline and is used to circulate air to cool these heating elements; The control unit is connected to the static inverter, bypass switch, main circuit switch and cooling system through signal lines to coordinate and control various devices during the start and stop process; The control module is connected to the static inverter, cooling system, and control unit through data transmission lines. It is used to create a virtual model of the SFC system and perform interactive simulations with real-time and historical data to optimize the adjustment of various parameters during the unit startup process.

2. A pumped storage unit air-cooled static inverter start-up control system according to claim 1, characterized in that: The steps for low-frequency starting of a synchronous motor controlled by a static inverter are as follows: The static inverter first starts to output low-frequency pulsating current to control the stator current and excitation current of the synchronous motor. As the pulsating current gradually increases, the static inverter gradually increases the torque of the synchronous motor, generating an unbalanced torque, thereby driving the synchronous motor to start slowly. During this low-frequency starting phase, the bypass switch is closed, so that the output current of the static inverter directly acts on the stator winding of the synchronous motor, thereby further accelerating the motor through pulsating operation; As the speed of the synchronous motor gradually increases, when it reaches the predetermined speed, the motor enters the synchronous motor drag mode, at which time the pulsating operation mode ends. When the speed of the synchronous motor reaches 10% of the rated speed, the control unit issues a command to cut off the bypass switch and close the main circuit switch; After the main circuit breaker is closed, the motor switches from the low-frequency pulsating operation mode to the normal three-phase rotating magnetic field operation, and the motor enters a stable synchronous operation state. Thereafter, the motor continues to accelerate in the synchronous drag mode until it reaches the rated speed; When the motor reaches the rated speed, the static inverter gradually exits operation and the motor switches to being directly powered by the power grid, completing the entire startup process.

3. A pumped storage unit air-cooled static inverter start-up control system according to claim 2, characterized in that: The steps for the cooling fan to circulate air to cool the heating element are as follows: Before the static inverter is started, the control unit first detects the operating status of the cooling fan, and sends a start signal after confirming that the cooling system is normal. The cooling fan starts to run. The cooling fan is connected to the main circuit component of the SFC through a pipeline to form an air circulation cooling channel to provide continuous cooling for the heating elements in the main circuit. After the cooling fan is started, cold air is continuously delivered to the heating element area of ​​the SFC through the pipe. After absorbing the heat generated by the heating element, the air is discharged to the outside through the circulation system to reduce the temperature of the main circuit components. During the cooling process, the temperature sensor monitors the temperature change of the SFC main circuit in real time and feeds the temperature back to the control unit. Based on the fed-back temperature data, the cooling fan will automatically adjust the wind speed and cooling intensity to provide sufficient cooling support at each stage of SFC startup and motor acceleration. After the motor is started and switched to direct power supply from the grid, the cooling fan will continue to run for a period of time to ensure that the temperature of the main circuit components gradually drops to a safe level. Finally, the control unit issues a command based on the real-time monitoring results of the temperature sensor to stop the operation of the cooling fan.

4. A pumped storage unit air-cooled static inverter start-up control system according to claim 3, characterized in that: The temperature sensor monitors the temperature change of the SFC main circuit in real time and feeds the temperature back to the control unit. According to the feedback temperature data, the cooling fan will automatically adjust the wind speed and cooling intensity in the following steps: Temperature sensors are installed in the key heating element areas of the main circuit components to monitor the temperature changes in these areas in real time. The temperature sensors will continuously collect temperature data of the heating elements in the main circuit; The temperature sensor transmits the collected temperature data of the SFC main circuit heating element area to the control unit in real time. The control unit presets the temperature threshold. Then, after receiving the temperature data, the received temperature data is compared with the preset temperature threshold of the system, and the corresponding adjustment instructions are generated according to the threshold comparison result and sent to the cooling fan through the signal line, instructing it to increase or decrease the wind speed and cooling intensity.

5. A pumped storage unit air-cooled static inverter start-up control system according to claim 4, characterized in that: When the control unit sends an adjustment command, if it detects that the temperature rises, the control unit will increase the wind speed or cooling intensity of the cooling fan; if the temperature drops to a normal range, the cooling fan will reduce the wind speed or intensity.

6. A pumped storage unit air-cooled static inverter startup control system and control method according to claim 5, characterized in that: The control unit can also analyze the temperature change trend over a period of time through a linear regression algorithm, the steps are as follows: Continuously collect and store real-time data from the temperature sensor, then select the time window for regression analysis, determine the amount of data used to fit the linear regression model, then use the temperature data as the dependent variable Y and time as the independent variable X, and fit a straight line through the linear regression algorithm to describe the temperature change trend over the past period of time. The linear regression equation is expressed as Y=β0+β1, where Y is the temperature value, X is the time, β0 is the intercept, and β1 is the rate of change of time and temperature, which is expressed as: X i It's time, Y i is the corresponding temperature, and They are the average values ​​of time and temperature respectively. According to the positive or negative value of the slope β1, it is predicted whether the temperature will rise or fall. If the slope is positive, it means that the temperature is rising; if the slope is negative, it means that the temperature is falling.

7. A pumped storage unit air-cooled static inverter start-up control system according to claim 6, characterized in that: The control module obtains data from the system in real time, including the status data of the static inverter, the temperature data of the cooling system, and the operation instructions issued by the control unit. In addition to receiving real-time data, the control module also stores the historical data of the SFC system in the past operation. Then, based on the collected real-time data and historical data, the control module creates a virtual model of the SFC system to simulate the system operation effect under different parameter settings. Subsequently, through the virtual model, the control module performs interactive simulation of real-time data and historical data. Then, the control module compares the currently collected real-time data with the historical data in the virtual model to predict what will happen in the future. Finally, according to the current real-time load and the feedback of the virtual model, the current parameters are dynamically optimized to make the current change smooth during the motor startup process. In addition, the control module can dynamically adjust the switching timing of the bypass switch and the main circuit switch according to the optimal switching point fed back by the virtual model, so that the system can complete the switch switching at the appropriate time.

8. A pumped storage unit air-cooled static inverter start-up control system according to claim 7, characterized in that: The steps to create a virtual model of the SFC system are: First, historical data combined with deep neural networks are used to establish and train machine learning models, so that the machine learning model can understand the changing patterns of different parameters at startup and the relationship between the parameters. Then, physical models of the components of the system are established. The static inverter model can describe the relationship between current, voltage and torque based on circuit theory and power equations, where the formula Calculate the output current I(t) of the static inverter, where V(t) is the voltage at time t and Z(t) is the impedance. Then, for the synchronous motor model, use the mechanical equations and electromagnetic formulas to describe the dynamic response of the motor, including the stator current I s The relationship between speed ω(t) and torque T(t) is expressed as: T(t) = k m I s (t)·ω(t), where k m is the motor constant, the cooling system is simulated by the heat conduction equation, and the wind speed v of the cooling fan f The relationship between (t) and the temperature drop rate ΔT(t) is: ΔT(t) = α·v f (t)-β·P(t), where α and β are system constants and P(t) is the heat load of the system; Next, the coupling between components is simulated. The static inverter, synchronous motor and cooling system interact with each other. As the synchronous motor speed ω(t) increases, the cooling fan speed v f (t) needs to be adjusted dynamically to maintain a suitable temperature. The expression of its coupling relationship is: f (t) = f(ω(t), T(t)). Then, when creating a virtual model, the physical model is combined with the machine learning model. The real-time data of the system is collected through the data transmission line, and the data is input into the virtual model for simulation. The model can predict the future state of the system and identify potential current overshoot or overtemperature problems based on the prediction results of physical rules and historical data. The expression is: I pred (t) = I real (t)+ΔI(t)where I pred (t) is the predicted current change trend, I real (t) is the current current, ΔI(t) is the current change predicted based on historical data and machine learning, and finally, the parameters during the startup process are continuously adjusted according to real-time feedback. The virtual model dynamically adjusts the current output of the static inverter based on the feedback, and its expression is: I(t)=I pred (t)-γ·f b (t) where f b (t) is the feedback error, γ is the adjustment coefficient, and the wind speed of the cooling fan is also adjusted according to the temperature feedback.

9. A method for starting and controlling an air-cooled static frequency converter of a pumped storage unit, characterized in that: The invention comprises the start-up control of an air-cooled static frequency converter and the stop control of an air-cooled static frequency converter, wherein the start-up control method of the air-cooled static frequency converter comprises the following steps: Step A1: The unit LCU issues a command to open the input / output transformer cooling water electric valve and ensure that the cooling water valve is open; Step A2: After receiving the start command, the SFC starts the SFC start operation. If the SFC start fails, the process is terminated. If successful, proceed to the next step. Step A3: SFC issues an input / output variable oil pump start command and starts the fan. Then, it determines whether the flow of the input / output variable oil pump is normal. If not, the process terminates. If normal, proceed to the next step. Step A4: The fans of the network bridge cabinet, the machine bridge cabinet and the reactor cabinet start running. Then, it is determined whether the fans are running normally. If not, the process is terminated. If the fans are running normally, proceed to the next step. Step A5: SFC issues a bypass switch closing command to turn on the bypass switch. Next, it is determined whether the bypass switch is closed successfully. If not, the process is terminated. If successful, the process proceeds to the next step. Step A6: SFC monitors the unit frequency and reaches the switching frequency. Then, it determines whether the unit has reached the target frequency. If not, the process terminates. If it has reached the target frequency, it proceeds to the next step. Step A7: SFC issues a main circuit switch closing command to connect the main circuit, and then determines whether the main circuit switch is closed successfully. If not, the process terminates; if successful, proceed to the next step; Step A8: SFC sends an input switch closing request, and the unit LCU selects to close the SFC input switch. Then, it is determined whether the SFC input switch is successfully closed. If not, the process is terminated. If successful, the startup process is completed. Step A9: SFC startup is completed and the system runs normally.

10. A method for starting and controlling an air-cooled static frequency converter of a pumped storage unit according to claim 9, characterized in that: The air-cooled static inverter stop control method includes the following steps: Step S1: The unit LCU issues a command to close the outlet switch or perform synchronous closing operation. If the outlet switch closing or synchronous closing signal is successful, proceed to the next step; Step S2: The SFC issues an output switch opening command to disconnect the SFC output switch. Then, it is determined whether the SFC output switch is opened successfully. If not, the process is terminated; if successful, the process proceeds to the next step. Step S3: SFC issues a main circuit switch opening command, and then determines whether the main circuit switch is opened successfully. If not, the process terminates; if successful, proceed to the next step; Step S4: SFC issues a blower stop command and an output variable oil pump stop command to shut down the auxiliary equipment. Next, it is determined whether the blower and the output variable oil pump are successfully stopped. If not, the process is terminated; if successful, proceed to the next step. Step S5: SFC issues a command to close the input / output transformer cooling water electric valve, and then determines whether the cooling water electric valve is successfully closed. If not, the process terminates; if successful, proceed to the next step; Step S6: The SFC system is completely stopped and the process ends.

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