A direct current transformer for series connection of locomotive catenary

Abstract

The application discloses a DC transformer for locomotive catenary series connection, comprising an intelligent voltage regulation module, a power automatic regulation module, a power support module, a bypass switching and protection module. The intelligent voltage regulation module collects voltage and current data in real time, dynamically regulates and controls the parameters of the power automatic regulation module; the power automatic regulation module realizes voltage conversion and harmonic suppression, and outputs stable DC voltage; the power support module releases energy storage compensation power when the locomotive is climbing or starting under heavy load, suppresses voltage sudden drop, recovers and regenerates electric energy to charge energy storage when the locomotive is descending; the bypass switching module completes seamless switching of the main and bypass circuits during failure or maintenance, and guarantees continuous power supply; the protection module monitors the state of each module and triggers graded protection, and realizes input and output electrical isolation. The transformer can be connected in series in multiple units, and through cooperative voltage stabilization and secondary calibration, solves the problems of voltage attenuation and harmonic pollution of the catenary in a long distance, outputs the rated power supply voltage of the locomotive, adapts to the harsh working conditions underground, and guarantees efficient and safe operation of the mine locomotive.

Description

Technical Field

[0001] This application relates to the field of mining power equipment technology, and in particular to a DC transformer for use in series connection of locomotive overhead contact lines. Background Technology

[0002] In deep mining operations, electric locomotives are the core equipment for underground material transportation, and the stability of their power supply system directly determines the mine's production efficiency and operational safety. Currently, DC traction power supply systems have been widely adopted in large and medium-sized non-ferrous metal mines in China. However, existing DC traction power supply systems for mining locomotives mostly use diode rectifiers, which present the following technical problems: I. The inherent nonlinear characteristics of diode rectifiers cause severe distortion of the current waveform on the grid side, which exacerbates the losses of locomotive electrical equipment.

[0003] Second, the output voltage of the diode rectifier is not adjustable. The number of locomotives running on the locomotive contact network changes according to different production tasks. When multiple locomotives are transporting at the same time, the output torque of the electric locomotive is insufficient, causing damage to the equipment and components on the locomotive.

[0004] Third, when dealing with a drop in DC voltage on the contact network, traditional diode rectifiers typically use parallel diode rectifiers, which requires additional AC high and low voltage distribution rooms and a large number of wires and cables.

[0005] Therefore, there is an urgent need to develop a DC transformer that can adapt to underground mining conditions, suppress harmonic pollution, and ensure continuous power supply. Summary of the Invention The main objective of this application is to provide a DC transformer for series connection of locomotive contact network, so as to solve the technical problems of severe voltage attenuation, prominent harmonic pollution and unadjustable voltage in existing mining locomotive contact networks.

[0006] This application provides a DC transformer for series connection of locomotive contact network, employing the following technology: A DC transformer for use in series connection of locomotive overhead contact line, comprising: The intelligent voltage regulation module is used to collect the input DC voltage, output voltage and load current of the locomotive contact network in real time, and generate regulation parameters and control commands to realize series coordinated voltage regulation and output, secondary voltage calibration and voltage regulation self-learning. The power automatic adjustment module is used to perform DC / AC inversion, high-frequency transformation and AC / DC rectification and filtering on the input DC voltage, output the locomotive's rated power supply voltage and suppress harmonic interference in voltage transformation; The power support module is bidirectionally connected to the intelligent voltage regulation module and the overhead contact line power supply circuit. It is used to quickly release electrical energy to support the voltage when the overhead contact line starts under heavy load, recover the regenerative braking energy of the locomotive for charging and energy storage when the locomotive brakes downhill, and perform charging and discharging control according to the overhead contact line voltage status and the locomotive operating conditions. The bypass switching module is used to monitor the fault and maintenance status of the automatic power adjustment module and perform seamless switching between the main and bypass circuits according to the control command. The protection module is used to collect the operating status data of each module and generate graded protection trigger signals to achieve electrical isolation between transformer input and output and graded fault protection.

[0007] Optionally, multiple DC transformers can be connected in series to the locomotive contact network to form a full-line voltage compensation network for the locomotive contact network. The DC transformers can adaptively adjust the input DC voltage of the locomotive contact network and output the rated power supply voltage of the locomotive to achieve power supply for the locomotive contact network.

[0008] Optionally, the completion of series coordinated voltage regulation and secondary calibration of output and voltage includes the following steps: The input DC voltage, output voltage, and load current of the locomotive's overhead contact system are acquired in real time through voltage and current acquisition components. The output voltage is compared with the locomotive's rated power supply voltage, the voltage deviation is calculated, and it is determined whether the voltage deviation exceeds a preset threshold. Based on the voltage deviation value and the load current, dynamic control parameters are generated and transmitted to the power automatic adjustment module; When multiple DC transformers are connected in series, the operating status data of adjacent DC transformers are received through the communication interface, and the automatic power adjustment module is adjusted synchronously according to the control parameters to achieve coordinated voltage stabilization of the entire line. The control feedback data of the automatic power adjustment module is collected in real time, and the output voltage is calibrated a second time.

[0009] Optionally, the synchronous self-adjustment power automatic regulation module to achieve coordinated voltage regulation of the entire line includes the following steps: Establish a network communication system and assign a unique node identifier to each DC transformer connected in series. Each DC transformer node uploads its own operating status data to the network control terminal in real time through the network communication network; The network control terminal generates voltage regulation reference values ​​and coordinated control commands for each DC transformer node; Each DC transformer node executes the coordinated control command, generates control parameters based on its own operating status data according to the voltage regulation reference value, and adjusts its own automatic power regulation module according to the control parameters.

[0010] Optionally, the network control terminal generates voltage regulation reference values ​​and coordinated control commands for each DC transformer node, including the following steps: The network control terminal collects real-time data on voltage distribution, load distribution, and voltage attenuation of the entire locomotive contact network and establishes a dynamic model of the locomotive contact network power supply conditions. The optimal voltage compensation amplitude for each DC transformer node is calculated based on the dynamic model of the locomotive overhead contact line power supply condition, and a voltage regulation reference value is generated.

[0011] Optionally, the secondary calibration of the output voltage includes the following steps: After the power automatic adjustment module's operating parameters are adjusted, real-time data of the output voltage is continuously collected, and the deviation value of the adjusted output voltage is calculated. The adjusted voltage deviation value is compared with a preset calibration threshold. If the adjusted voltage deviation value is greater than the preset calibration threshold, a secondary adjustment parameter is generated. The operating parameters of the automatic power adjustment module are corrected according to the secondary control parameters until the output voltage deviation is within the preset threshold. The data from the secondary calibration process is stored and analyzed to form a voltage regulation self-learning database, providing a reference for subsequent regulation of similar output voltage deviation scenarios.

[0012] Optionally, forming the voltage regulation self-learning database includes the following steps: Record the output voltage deviation value of each secondary calibration, the operating parameters of the automatic power adjustment module, and the load current to form a voltage regulation self-learning database; The optimal voltage regulation parameters under different operating conditions were obtained by analyzing the voltage regulation self-learning database. When the same output voltage deviation value and operating condition are detected, the optimal voltage regulation parameter is directly called.

[0013] Optionally, the step of rapidly releasing electrical energy to support the voltage during the start-up of a high-load contact network includes the following steps: Real-time monitoring of the change rate of contact network voltage and load current; when the rate of increase of load current within a preset time window exceeds the start-up judgment threshold, it is predicted that a large load is connected. The real-time contact network voltage is compared with the discharge intervention threshold, which is set to 90%-95% of the rated voltage. When the contact network voltage is lower than the discharge intervention threshold and the load current continues to increase, the high load starting condition is confirmed. Immediately generate a power support start command to control the bidirectional DC / DC converter to operate in maximum power mode, and the supercapacitor energy storage unit to discharge rapidly, injecting compensation current into the contact network; Monitor the recovery of the contact network voltage in real time and dynamically adjust the discharge power to ensure that the contact network voltage recovers quickly to within ±2% of the rated value.

[0014] Optionally, the power support module performs charge and discharge control according to the contact network voltage status, including the following steps: The input DC voltage, output voltage, and load current of each section of the overhead contact line are monitored in real time using voltage and current acquisition components. The real-time monitored contact network voltage data is compared with the preset voltage threshold to determine the contact network voltage status. When the contact wire voltage is lower than the discharge intervention threshold and the load current is greater than the starting current threshold, it is determined to be a large load starting condition. A discharge control command is generated to control the supercapacitor energy storage unit to release electrical energy to the contact wire, supporting the contact wire voltage to recover to the rated value. When the contact network voltage recovers to the rated value and the stable duration reaches the preset exit delay, a power support exit command is generated to control the supercapacitor energy storage unit to stop discharging. When the contact network voltage is higher than the charging start threshold and the locomotive is detected to be in a downhill regenerative braking condition, a charging control command is generated to control the supercapacitor energy storage unit to receive feedback energy for charging and energy storage.

[0015] Optionally, the step of seamlessly switching between the main and bypass circuits according to the control command includes the following steps: The system receives real-time operating status data from the automatic power adjustment module to determine whether the automatic power adjustment module is in a fault or maintenance shutdown state. When the power automatic adjustment module is detected to be in a fault or maintenance shutdown state, the intelligent voltage regulation module sends a circuit switching command to the bypass switching module. The bypass switching module closes the bypass power supply circuit and disconnects the main power supply circuit according to the circuit switching command to achieve power supply switching; During bypass power supply, the bypass switching module continuously monitors the operating status data of the automatic power adjustment module; After detecting that the operating status data of the automatic power adjustment module has returned to normal, the intelligent voltage regulation module sends a circuit reset command; The bypass switching module closes the main power supply circuit, disconnects the bypass power supply circuit, and restores the normal power supply to the main circuit according to the circuit reset command. During the switching and reset process, the loop current and voltage data of the main circuit and bypass circuit are collected in real time.

[0016] The advantages of this application are as follows: The DC transformer for series connection of locomotive contact networks proposed in this application can be connected in series to form a voltage compensation and boosting network for the entire contact network, overcoming voltage attenuation caused by excessively long lines. Through the dynamic regulation of the intelligent voltage regulation module and the boosting of the power automatic adjustment module, the voltage attenuation caused by line impedance can be effectively compensated, stabilizing the contact network output voltage within the locomotive's rated power supply voltage range. The power automatic adjustment module uses an electromagnetic interference filter component to specifically filter out harmonics generated during voltage transformation, controlling the harmonic distortion rate below the standard limit. The bypass switching module and the power automatic adjustment module form a main-bypass dual circuit. When the power automatic adjustment module fails or needs maintenance, it can quickly and seamlessly switch between the main circuit and the bypass circuit without power interruption during the switching process. Attached Figure Description

[0017] Figure 1 A timing diagram of a DC transformer for series connection of a locomotive contact network provided in one embodiment of this application; Figure 2 This is a diagram of a series-connected DC transformer network architecture for a locomotive overhead contact system according to an embodiment of this application. Figure 3 This is an interaction diagram of an intelligent voltage regulation module according to an embodiment of this application; Figure 4 This is an architectural diagram of an intelligent voltage regulation module according to an embodiment of this application; Figure 5 This is a structural diagram of an automatic power adjustment module according to an embodiment of this application; Figure 6 This is a schematic diagram illustrating the working process of a DC / AC inverter circuit for an automatic power adjustment module according to an embodiment of this application.

[0018] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The main solution in this application's embodiments is: A DC transformer for use in series connection of locomotive overhead contact line, comprising: The intelligent voltage regulation module is used to collect the input DC voltage, output voltage and load current of the locomotive contact network in real time, and generate regulation parameters and control commands to realize series coordinated voltage regulation and output, secondary voltage calibration and voltage regulation self-learning. The automatic power adjustment module is used to perform DC / AC inversion, high-frequency transformation and AC / DC rectification and filtering on the input DC voltage, output the locomotive's rated power supply voltage and suppress harmonic interference in voltage transformation; The bypass switching module is used to monitor the fault and maintenance status of the automatic power adjustment module and perform seamless switching between the main and bypass circuits according to the control command. The protection module is used to collect the operating status data of each module and generate graded protection trigger signals to achieve electrical isolation between transformer input and output and graded fault protection.

[0020] This application provides a DC transformer for series connection of locomotive contact network. It achieves precise adjustment of output voltage by dynamically regulating the working parameters of the power automatic adjustment module through the intelligent voltage regulation module; it filters out harmonics generated during voltage transformation through the power automatic adjustment module, reducing the loss of locomotive electrical equipment; and it quickly completes the seamless switching between the main circuit and the bypass circuit through the bypass switching module, with no power interruption during the switching process, ensuring continuous power supply to the contact network of mining locomotives.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can understand it.

[0022] refer to Figure 1 One embodiment of this application provides a DC transformer for series connection of a locomotive overhead contact line. (See reference...) Figure 2 Four DC transformers, DCT-01, DCT-02, DCT-03, and DCT-04, are deployed in series along the overhead contact line in a 2.5-kilometer-long mine transport roadway, with a spacing of approximately 600 meters between them.

[0023] The intelligent voltage regulation module is used to collect the input DC voltage, output voltage and load current of the locomotive's overhead contact line in real time, and generate regulation parameters and control commands to complete series coordinated voltage regulation and output, secondary voltage calibration and voltage regulation self-learning.

[0024] In one specific embodiment, reference is made to Figure 3 The system acquires the input DC voltage, output voltage, and load current of the locomotive's overhead contact system in real time through voltage and current acquisition components; compares the output voltage with the locomotive's rated power supply voltage, calculates the voltage deviation, and determines whether the voltage deviation exceeds a preset threshold; and dynamically generates the operating parameters of the automatic power adjustment module based on the voltage deviation and load current, and sends them to the automatic power adjustment module.

[0025] In the specific implementation process, refer to Figure 4 After the intelligent voltage regulation module is activated, it uses a fixed acquisition period of 10ms. The voltage acquisition component collects the input DC voltage and output voltage of the locomotive's overhead contact line in real time, while the current acquisition component collects the load current. The voltage acquisition component uses a LEM LV 25-P voltage sensor, with a range of 0-1000VDC, an accuracy of ±0.1%FS, and a response time ≤1μs. The current acquisition component uses a LEM LA 1000-P current sensor, with a range of 0-1200A DC, an accuracy of ±0.2%FS, and a response time ≤2μs.

[0026] In the intelligent voltage regulation module, the FPGA chip used is a Xilinx XC7K325T. The Xilinx XC7K325T performs moving average filtering and spike removal processing on the data collected by the voltage and current acquisition components to remove noise data caused by downhole electromagnetic interference. Moving average filtering is a time-domain low-pass filtering method that smooths random noise through an arithmetic average within a fixed-length window. This embodiment uses a time-domain low-pass filter with a 10ms acquisition period and a 5-point window length to smooth the random noise generated by downhole electromagnetic interference. Spike removal removes sudden spike noise. The System DSP chip used is a TI TMS320F28377D, which synchronously acquires the operating status data of the automatic power adjustment module, the monitoring data of the protection module, the charging and discharging status data of the power support module, and the loop on / off status data of the bypass switching module through an internal high-speed bus, completing the aggregation of multi-dimensional data. The aggregated data is uploaded to the network control terminal in real time via the communication interface, and stored locally by the TI TMS320F28377D to provide a basis for subsequent voltage regulation analysis and fault tracing.

[0027] The control DSP chip selected is the TI TMS320F28069. The TI TMS320F28069 can complete output voltage deviation calculation and threshold determination in a short time, eliminating the need for an external ADC chip and directly generating the PWM signal required for voltage regulation. The TITMS320F28069 compares the filtered output voltage with the locomotive's rated power supply voltage in real time to calculate the output voltage deviation value. in, This is the output voltage deviation value; This is the filtered output voltage. ; The rated power supply voltage for the locomotive, .

[0028] The preset voltage threshold is the locomotive's rated power supply voltage. V, meaning 495V DC to 555V DC. The preset discharge threshold is 92% of the rated voltage, i.e., 506V; the preset charging start threshold is 102.7% of the rated voltage, i.e., 565V. The Control DSP performs operating condition judgment based on voltage deviation, load current change rate, and power support module SOC status: like And in non-high load impact conditions, maintain the current state and only continue monitoring; if Furthermore, under conditions other than large load impacts, the power generation automatic adjustment module adjusts the parameters; if , If the discharge threshold is reached and the load current rises sharply, a discharge command for the power support module is generated; if Furthermore, when the current is reversed and the road is downhill, a charging command is generated for the power support module.

[0029] The control DSP generates regulation parameters and commands, which are then sent to each execution module via an internal high-speed bus. When the power support module is in discharge support mode, the control DSP executes a cooperative control algorithm to correct the voltage regulation target value of the automatic power adjustment module. in, The coupling coefficient is... ; This represents the current discharge power. ; This is the corrected target voltage.

[0030] For example, Then the corrected target voltage The Control DSP recalculates the duty cycle based on the corrected target voltage, ensuring that the automatic power adjustment module and the power support module work together to avoid voltage over-adjustment or system oscillation.

[0031] If the output voltage deviation does not exceed the preset voltage threshold, the intelligent voltage regulation module maintains its current control state, continuously acquiring and monitoring data without sending operating parameters to the power automatic adjustment module. If the output voltage deviation exceeds the preset voltage threshold, the TI TMS320F28069 dynamically generates control parameters based on the output voltage deviation, load current, and the current operating parameters of the power automatic adjustment module, and sends these parameters to the power automatic adjustment module.

[0032] , The preset voltage threshold requires activation of the control mechanism. The load current is 350A, and the current operating parameters of the automatic power adjustment module are the switching frequency. Duty cycle Theoretical output voltage ,in The turns ratio, The output voltage after rectification and filtering is The target output voltage of 550V corresponds to a transformer secondary output of approximately 565V, requiring a specific duty cycle. for: in, Target duty cycle; The target voltage on the secondary side of the transformer. ; The turns ratio, .

[0033] By introducing load compensation coefficients and temperature compensation coefficients, the final target duty cycle is calculated. : in, This is the load compensation coefficient. ; This is the temperature compensation coefficient. .

[0034] Duty cycle adjustment To increase the output voltage, the duty cycle is reduced. Because a boost topology is used, taking Buck output as an example, the duty cycle needs to be increased.

[0035] The TI TMS320F28069 generates the final operating parameters based on the output voltage deviation and load current. in, ; ; . The amplitude is limited to ±10%. Final duty cycle setting. for: The generated operating parameters are sent to the power automatic adjustment module.

[0036] In one specific embodiment, when multiple DC transformers (DCTs) are connected in series, the operating status data of adjacent DC transformers are received through the communication interface, and the operating parameters of the automatic power adjustment module are adjusted synchronously to achieve coordinated voltage stabilization of the entire line.

[0037] In the specific implementation process, a network communication network based on industrial Ethernet and RS485 dual buses is used. Each DC transformer is assigned a unique node identifier: DCT-01 is node address 0x01, DCT-02 is node address 0x02, DCT-03 is node address 0x03, and DCT-04 is node address 0x04. The node identifier is stored in the System DSP chip TITMS320F28377D of each DC transformer. Each node uploads its own operating status data to the network control terminal via the network communication network at a fixed interval of 50ms.

[0038] The network control terminal aggregates real-time voltage distribution data, load distribution data, and voltage decay data for the entire locomotive overhead contact line, forming a database of the entire line's operating status. Voltage distribution data includes the DC input voltage value, output voltage value, and actual output voltage difference between adjacent nodes uploaded by each node; load distribution data includes the real-time load current and load change rate of each node; voltage decay data is the voltage decay value, calculated using the following DC line voltage decay formula: in, This represents the voltage attenuation value. This represents the load current at each node; The length of the line in the section; This refers to the cross-sectional area of ​​the locomotive's overhead contact line conductor. is the resistivity of the conductor.

[0039] The network control terminal establishes a dynamic model of the locomotive's overhead contact line power supply conditions based on the entire line's operational status database. Specifically, this model adopts a distributed parametric line model, equating the overhead contact line to multiple cascaded π-type networks, each corresponding to a DC transformer power supply section. The model's state equations are: in, For the first Each node output voltage; DC input voltage; This is the load current; This refers to the internal resistance of a DC transformer. For filtering inductors; Line current; Line resistance.

[0040] The optimal voltage compensation amplitude for each DC transformer node is calculated based on the dynamic model of the locomotive's overhead contact line power supply condition, generating a voltage regulation reference value. Specifically, the network control end establishes a constrained optimization problem with the optimization objectives of minimizing the voltage variance across the entire line, ensuring the terminal voltage meets the locomotive's minimum operating voltage of 530V, and ensuring that the output voltage of each node does not exceed the equipment's upper limit of 580V. The objective function is: in, Provide the target supply voltage. ; This is the line voltage drop weighting coefficient. ; For the number of nodes, .

[0041] The constraints are: , , .

[0042] A quadratic programming algorithm is used to search for the solution within the constraints. smallest Combinatorial. Quadratic programming is a constrained optimization algorithm that aims to find the minimum or maximum value of a quadratic function. The optimal solution obtained is... This is the voltage adjustment reference value for each DCT.

[0043] In some embodiments, the weight coefficients in the objective function It can be dynamically adjusted; if priority is given to ensuring the terminal voltage, then it should be reduced. If reducing line loss is prioritized, then the increase will be greater. The upper limit of the node output voltage in the constraint conditions can be adjusted according to the equipment temperature derating. When the temperature exceeds 80℃, the upper limit is reduced to 570V, and when it exceeds 90℃, it is reduced to 560V.

[0044] The network control terminal will be optimal If the deviation is greater than the dead zone when compared with the current actual output voltage value, a control command is generated and sent to each DCT; if the deviation is less than the dead zone, no action is taken.

[0045] In one specific embodiment, the control feedback data of the automatic power adjustment module is collected in real time to perform secondary calibration of the output voltage.

[0046] In the specific implementation process, after the initial adjustment of the power automatic adjustment module's operating parameters, the intelligent voltage regulation module immediately triggers a secondary calibration process. The voltage acquisition component continuously collects real-time data of the output voltage and calculates the actual deviation value of the adjusted output voltage. Specifically, after completing the initial adjustment of the power automatic adjustment module, the intelligent voltage regulation module uses the voltage acquisition component to continuously collect real-time data of the output voltage at a fixed acquisition period of 10ms, continuously collecting 10 points to form a sampling sequence. The initial adjustment target is to increase the output voltage from 512V to 550V. The sampled data after adjustment are: 553.2V, 552.8V, 553.5V, 554.1V, 553.9V, 554.3V, 554.0V, 553.7V, 554.2V, 554.1V. The FPGA chip Xilinx XC7K325T performs moving average processing on the sampled data of the sampling sequence to obtain the average value of the steady-state output voltage. ,Will With the locomotive's rated power supply voltage The comparison is performed, and the deviation value of the regulated output voltage is calculated using the Control DSP chip TI TMS320F28069. : The actual deviation of the regulated voltage is compared with the preset calibration threshold. If If a preset calibration threshold is set, it is considered that the accuracy requirements have been met by a single adjustment, and no secondary calibration is required; the process then ends. A preset calibration threshold is set to trigger a secondary calibration process. The preset calibration threshold is set to ±1.0V, meaning that secondary adjustment is triggered when the absolute value of the deviation is greater than 1.0V.

[0047] , The system determines that a secondary calibration is required. Furthermore, the deviation is determined to be positive, indicating overshoot, necessitating a reduction in the output voltage.

[0048] Based on the adjusted output voltage deviation, a secondary control parameter is generated using an adaptive step-size algorithm. The adaptive step-size algorithm is a closed-loop control algorithm that dynamically adjusts the duty cycle adjustment range based on the voltage deviation correction effect.

[0049] The initial step size is set to 0.5% / V of the duty cycle adjustment, and the base adjustment is calculated. : Considering the impact of a load current of 320A, a load compensation factor is introduced to calculate the actual adjustment amount: in, This is the load compensation coefficient. The calculation formula is: Among them, load current Rated current .

[0050] Calculated The current duty cycle is 72%, and the adjusted duty cycle is 70.25%.

[0051] The operating parameters of the automatic power adjustment module are corrected based on the secondary control parameters until the output voltage deviation is within the preset threshold. Specifically, after completing the secondary control, the output voltage is sampled again at a 10-millisecond cycle. The new sampling sequence is: 550.8V, 550.5V, 550.2V, 549.9V, 550.1V, 550.3V, 550.0V, 549.8V, 550.2V, 550.1V. The average output voltage is then calculated. The deviation value of the adjusted output voltage If the deviation value is within the preset threshold ±1.0V range, the second calibration is completed. If the deviation value still exceeds the threshold, the iteration continues: the step size of the second iteration is halved to 0.25% / V, the step size of the third iteration is halved again to 0.125% / V, and the iteration is repeated up to 5 times. If convergence is still not achieved after 5 iterations, a fault alarm is triggered, and the system switches to bypass power supply.

[0052] In one specific embodiment, the data from the secondary calibration process is stored and analyzed to form a voltage regulation self-learning database, providing a reference for subsequent regulation of similar output voltage deviation scenarios.

[0053] In the specific implementation process, the complete data of this secondary calibration is recorded in the voltage regulation self-learning database. The recorded content includes data such as DC input voltage, output voltage deviation, and load current. The intelligent voltage regulation module System DSP chip analyzes the voltage regulation self-learning database daily and clusters the recorded data in the database. For each operating condition group, all records within the group are analyzed to calculate the optimal voltage regulation parameters. When a node detects a new regulation requirement, the intelligent voltage regulation module first extracts the current operating condition characteristics and the output voltage deviation after the first regulation. Using the current operating condition characteristics as keywords, it searches for a matching operating condition group in the voltage regulation self-learning database. If a matching group is found, the System DSP directly calls the optimal voltage regulation parameters of that matching group and sends them directly to the power automatic adjustment module through the Control DSP.

[0054] The automatic power adjustment module is used to perform DC / AC inversion, high-frequency transformation and AC / DC rectification and filtering on the input DC voltage, output the locomotive's rated power supply voltage and suppress voltage transformation harmonic interference.

[0055] refer to Figure 5 In one specific embodiment, the automatic power adjustment module includes an EMI input filter, a DC / AC inverter circuit, a high-frequency transformer, an AC / DC rectifier circuit, an LC filter circuit, and an EMI output filter. The automatic power adjustment module operates as follows: it inverts the input DC voltage of the locomotive contact network to convert it into AC power; it then regulates the AC power, boosting it to a voltage amplitude matching the locomotive's rated power supply based on the actual voltage attenuation of the input DC voltage; it performs high-frequency rectification and filtering on the transformed AC power, converting it into a stable DC voltage output to the locomotive contact network; and it uses an electromagnetic interference filter to filter and suppress harmonic signals generated during voltage conversion.

[0056] In the specific implementation process, refer to Figure 6 The automatic power adjustment module receives the input DC voltage from the overhead contact line. The voltage is filtered out by an EMI input filter to remove high-frequency noise and then sent to the DC / AC inverter circuit. At the same time, the intelligent voltage regulation module generates a PWM drive command, which drives the SiCMOSFET in the DC / AC inverter circuit to turn on and off alternately through an isolation driver, converting DC power into a 50kHz AC square wave to complete the DC / AC inverter process.

[0057] The DC / AC inverter circuit adopts a full-bridge topology, consisting of an H-arm composed of four SiC MOSFET power switches. The SiC MOSFET power switches are Cree C3M0065090D, rated voltage 900V, rated current 36A, and on-resistance 65mΩ. The isolation driver is a Silicon Labs Si8239x, with an isolation voltage of 5kV and a propagation delay of 50ns.

[0058] A square-wave AC current is fed into a high-frequency transformer for voltage conversion. The transformer core uses TDK PC95 ferrite material with a saturation magnetic flux density of 530 mT at 100℃ and a turns ratio n = 1:1.167. Based on the actual voltage decay of the input voltage, the intelligent voltage regulation module dynamically adjusts the PWM duty cycle to compensate for voltage fluctuations. When the DC input voltage drops to 470V, the duty cycle increases from 50% to 54% to maintain the secondary voltage. Constant: in, DC input voltage, ; The turns ratio, ; Duty cycle, .

[0059] The AC power output from the secondary side of the high-frequency transformer is fed into an AC / DC rectifier circuit. The AC / DC rectifier circuit adopts a synchronous full-bridge topology, including four SiC MOSFEs. The SiC MOSFEs selected are Cree C3M0030090K, with an on-resistance of 30mΩ. An intelligent voltage regulation module generates a drive signal synchronized with the secondary voltage to achieve full-wave rectification. The rectified DC voltage is smoothed by an LC filter circuit. The filter inductor is a Magnetics Kool Mμ77930-A7 iron-silicon-aluminum magnetic ring with an inductance of 80μH and a saturation current of 500A; the filter capacitor is an EPCOS B32776 film capacitor with a capacitance of 470μF, a withstand voltage of 900V, and an ESR of 2mΩ. Calculate the output voltage after rectification and filtering: in, This is the output voltage after rectification and filtering; This refers to the secondary voltage of the high-frequency transformer. For rectified duty cycle, ; For the voltage drop in the rectifier stage, .

[0060] The automatic power adjustment module includes an EMI input filter and an EMI output filter. The EMI input filter is located at the front end of the DC / AC inverter circuit and adopts a π-type structure; the EMI output filter is located at the rear end of the LC filter and adopts an LC low-pass structure to address high-frequency rectification residual ripple and switching noise. Both the EMI input and output filters comprehensively suppress harmonic interference generated during voltage conversion.

[0061] The power support module is used to quickly release electrical energy to support the voltage when the overhead contact line starts under heavy load, recover the regenerative braking energy of the locomotive for charging and energy storage when the locomotive brakes downhill, and perform charging and discharging control according to the overhead contact line voltage status and locomotive operating conditions.

[0062] In one specific embodiment, the power support module includes a supercapacitor energy storage unit and a bidirectional DC / DC converter. The supercapacitor energy storage unit consists of a supercapacitor module, a voltage equalization management circuit, a temperature monitoring component, and a state of charge estimation unit.

[0063] In the specific implementation, the supercapacitor module uses Skeleton Technologies SCA0500 supercapacitor cells, with a rated voltage of 2.85V and a maximum current of 1200A. Each power support module is equipped with 240 cells, connected in an 80-series-3-parallel configuration, with a total capacity of 18.75F and a rated voltage of 228V, meeting the power support requirements of a single locomotive during startup. The bidirectional DC / DC converter adopts a bidirectional Buck-Boost topology, using SiC MOSFET power devices (Cree C3M0030090K), with a switching frequency of 50kHz, a rated power of 200kW, and an efficiency ≥98%. The charge / discharge control unit is integrated into the System DSP chip TITMS320F28377D, which collects supercapacitor voltage, current, and temperature data through an independent ADC channel to calculate the state of charge (SOC) in real time. The SOC calculation formula is: in, This is the current voltage of the supercapacitor; The supercapacitor has a rated voltage of 228V. The minimum operating voltage for supercapacitors is 120V.

[0064] The power support module performs charge and discharge control based on the contact network voltage status: Discharge Support Mode: At node DCT-02, when a 550kW heavy-haul locomotive starts 200 meters from the node, the System DSP of the intelligent voltage regulation module detects the following state changes: the contact network voltage momentarily drops from 550V to 485V, the load current rises sharply from 50A to 820A, and the rate of current rise... Upon detecting a high-load start-up condition, the System DSP immediately generates a discharge control command, activating the bidirectional DC / DC converter. The supercapacitor energy storage unit discharges to the contact network at a maximum power of 200kW, injecting a compensation current of approximately 400A. The contact network voltage recovers to 545V within 150ms. Subsequently, the Control DSP adjusts the discharge command parameters, reducing the power to 80kW and entering a maintenance mode. The discharge power is dynamically adjusted to ensure the contact network voltage remains stable within the range of 550V±2%. After the locomotive completes its start-up, the load current drops to 200A, and the voltage stabilizes at 550V for 5 seconds. The intelligent voltage regulation module generates a power support exit command, and the PSS-02 shuts down the bidirectional DC / DC converter, switching to standby mode.

[0065] Charging and Energy Storage Mode: The section where DCT-03 is located is a downhill section with a gradient of -5% and a length of 800 meters. The System DSP of the intelligent voltage regulation module detects the following states: the contact network voltage rises to 565V; the current direction reverses, with power flowing from the locomotive back to the contact network; combined with the track gradient data stored in the contact network geographic information system, it is confirmed that the current track section where the locomotive is located is a downhill section. The System DSP determines that the locomotive is currently in downhill regenerative braking mode, and the Control DSP generates a charging control command. The bidirectional DC / DC converter is activated to work in reverse, transferring the regenerative braking energy fed back by the locomotive to the supercapacitor energy storage unit. The charging power is dynamically adjusted according to the feedback power, with the maximum charging power limited to 150kW to prevent overcharging of the supercapacitor. When the supercapacitor SOC reaches 90% or the locomotive leaves the downhill section, charging stops and switches to standby mode. Approximately 280kJ of energy can be recovered during a single downhill braking operation, and the supercapacitor SOC increases from 30% to 75%.

[0066] Standby mode: When no charge / discharge command is received, the power support module is in standby mode, the status monitoring unit continues to work, reports SOC and temperature data in real time, and waits for the command from the intelligent voltage regulation module.

[0067] The bypass switching module is used to monitor the fault and maintenance status of the power automatic adjustment module and perform seamless switching between the main and bypass circuits according to the control commands.

[0068] In one specific embodiment, the operating status data of the automatic power adjustment module is received in real time to determine whether the automatic power adjustment module is in a fault or maintenance shutdown state. When the automatic power adjustment module is detected to be in a fault or maintenance shutdown state, the intelligent voltage regulation module sends a circuit switching command to the bypass switching module. The bypass switching module closes the bypass power supply circuit and disconnects the main power supply circuit according to the circuit switching command to realize power supply switching. During bypass power supply, the bypass switching module continuously monitors the operating status data of the automatic power adjustment module. After the operating status data of the automatic power adjustment module is detected to return to normal, the intelligent voltage regulation module sends a circuit reset command. The bypass switching module closes the main power supply circuit and disconnects the bypass power supply circuit according to the circuit reset command to restore normal power supply to the main circuit. During the switching and reset process, the circuit current and voltage data of the main circuit and bypass circuit are collected in real time.

[0069] In practice, the intelligent voltage regulation module receives real-time operating status data from the automatic power adjustment module every 10 milliseconds and judges the status of the automatic power adjustment module. The judgment conditions are as follows: all parameters are within the normal range, indicating normal operation; any module temperature > 100℃, indicating over-temperature and requiring shutdown; output current > 1000A, indicating overcurrent and requiring shutdown; DC bus voltage > 620V, indicating overvoltage and requiring shutdown; DC bus voltage < 380V, indicating undervoltage and requiring shutdown; remote maintenance command = 1, indicating maintenance and requiring shutdown.

[0070] At node DCT-03, the intelligent voltage regulation module detected a continuous rise in module temperature to 105℃, determining that the automatic power regulation module was in an over-temperature fault standby state and immediately initiating the switching process. The intelligent voltage regulation module sent a loop switching command to the bypass switching module, which confirmed receipt and parsed the command, switching to bypass power supply. During the bypass power supply process, the bypass switching module continuously monitored the operating status data of the automatic power regulation module. After 40 minutes of natural cooling and fault diagnosis, the temperature of the automatic power regulation module dropped to 75℃, and the insulation resistance recovered to 50MΩ, indicating a return to normal operation. The intelligent voltage regulation module then sent a loop reset command, which the bypass switching module confirmed receipt and parsed, switching back to main power supply. During the switching and reset processes, real-time acquisition of loop current and voltage data for both the main and bypass circuits was conducted.

[0071] The protection module is used to collect the operating status data of each module and generate graded protection trigger signals to complete the input and output electrical isolation and graded fault protection of the transformer.

[0072] In one specific embodiment, the protection module collects the operating status data of each module of the DC transformer in real time through sensing components; compares the operating status data of each module with a preset threshold to determine whether it is a fault state; and triggers corresponding graded protection actions for different fault states.

[0073] In the specific implementation process, the sensing components include temperature sensors, vibration sensors, and isolation amplifiers. At node DCT-02, the sensing components collect the operating status data of each module of the DC transformer at a certain moment as follows: automatic power adjustment module temperature 78℃, output current 420A, DC bus voltage 538V, intelligent voltage regulation module temperature 45℃, and DC transformer vibration acceleration 0.03g.

[0074] The protection module compares the operating status data of each module with preset thresholds, adopting a hierarchical threshold system: For each module, temperature <70℃ is considered normal, 70-85℃ is the first-level warning threshold, 85-100℃ is the second-level warning threshold, and >100℃ is the third-level warning threshold; output current <800A is considered normal, 800-900A is the warning threshold, 900-1000A is the power limiting threshold, and >1000A is the shutdown threshold; DC bus voltage 420-580V is considered normal, 400-420V or 580-600V is the warning threshold, 380-400V or 600-620V is the power limiting threshold, and <380V or >620V is the shutdown threshold; DC transformer vibration acceleration <0.1g is considered normal, 0.1-0.3g is the warning threshold, 0.3-0.5g is the power limiting threshold, and >0.5g is the shutdown threshold.

[0075] The current data comparison results are as follows: the automatic power adjustment module temperature is 78℃, which is within the 70-85℃ warning range; the intelligent voltage regulation module temperature is 45℃, which is within the normal range; and the output current... 420A is normal, DC bus voltage is 538V, which is normal, and DC transformer vibration acceleration is 0.03g, which is normal. Overall assessment: The automatic power adjustment module is in a warning state, not a fault state, triggering level one protection.

[0076] The protection module triggers corresponding tiered protection actions based on the warning status. A Level 1 warning triggers Level 1 protection; under Level 1 protection, the intelligent voltage regulating module reduces the switching frequency, reports the warning information to the network control terminal, and records the warning log, marking the timestamp and operating data. A Level 2 warning triggers Level 2 protection; under Level 2 protection, the intelligent voltage regulating module limits the output power to 70% of the rated value; the bypass switching module prepares for closing; and it sends support requests to adjacent nodes to negotiate load transfer. A Level 3 warning triggers Level 3 protection; under Level 3 protection, the automatic power regulation module is immediately shut down; the bypass switching module performs a main-bypass switchover; the protection module records all sampled data from 10 seconds before the fault to 5 seconds after the fault; and the intelligent voltage regulating module reports the fault shutdown status to the network control terminal.

[0077] In this embodiment, after the first-level protection takes effect, the module temperature drops to 72°C within 30 seconds, exits the warning state, and resumes normal operation.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0079] In the description of this application, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0080] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0081] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0082] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0083] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0084] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

[0085] Furthermore, although the operations of the method of this application are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

Claims

1. A DC transformer for use in series connection of locomotive overhead contact lines, characterized in that, include: The intelligent voltage regulation module is used to collect the input DC voltage, output voltage and load current of the locomotive contact network in real time, and generate regulation parameters and control commands to realize series coordinated voltage regulation and output, secondary voltage calibration and voltage regulation self-learning. The power automatic adjustment module is used to perform DC / AC inversion, high-frequency transformation and AC / DC rectification and filtering on the input DC voltage, output the locomotive's rated power supply voltage and suppress harmonic interference in voltage transformation; The power support module is bidirectionally connected to the intelligent voltage regulation module and the overhead contact line power supply circuit. It is used to quickly release electrical energy to support the voltage when the overhead contact line starts under heavy load, recover the regenerative braking energy of the locomotive for charging and energy storage when the locomotive brakes downhill, and perform charging and discharging control according to the overhead contact line voltage status and the locomotive operating conditions. The bypass switching module is used to monitor the fault and maintenance status of the automatic power adjustment module and perform seamless switching between the main and bypass circuits according to the control command. The protection module is used to collect the operating status data of each module and generate graded protection trigger signals to achieve electrical isolation between transformer input and output and graded fault protection.

2. A DC transformer for series connection of locomotive contact network according to claim 1, characterized in that, Multiple DC transformers can be connected in series to the locomotive contact network to form a full-line voltage compensation network for the locomotive contact network. The DC transformers adaptively adjust the input DC voltage of the locomotive contact network and output the rated power supply voltage of the locomotive to realize the power supply of the locomotive contact network.

3. A DC transformer for series connection of locomotive contact network according to claim 2, characterized in that, The completion of series coordinated voltage regulation and secondary calibration of output and voltage includes the following steps: The input DC voltage, output voltage, and load current of the locomotive's overhead contact system are acquired in real time through voltage and current acquisition components. The output voltage is compared with the locomotive's rated power supply voltage, the voltage deviation is calculated, and it is determined whether the voltage deviation exceeds a preset threshold. Based on the voltage deviation value and the load current, dynamic control parameters are generated and transmitted to the power automatic adjustment module; When multiple DC transformers are connected in series, the operating status data of adjacent DC transformers are received through the communication interface, and the automatic power adjustment module is adjusted synchronously according to the control parameters to achieve coordinated voltage stabilization of the entire line. The control feedback data of the automatic power adjustment module is collected in real time, and the output voltage is calibrated a second time.

4. A DC transformer for series connection of locomotive contact network according to claim 3, characterized in that, The synchronous self-adjusting automatic power regulation module achieves coordinated voltage stabilization across the entire line, including the following steps: Establish a network communication system and assign a unique node identifier to each DC transformer connected in series. Each DC transformer node uploads its own operating status data to the network control terminal in real time through the network communication network; The network control terminal generates voltage regulation reference values ​​and coordinated control commands for each DC transformer node; Each DC transformer node executes the coordinated control command, generates control parameters based on its own operating status data according to the voltage regulation reference value, and adjusts its own automatic power regulation module according to the control parameters.

5. A DC transformer for series connection of locomotive contact network according to claim 4, characterized in that, The network control terminal generates voltage regulation reference values ​​and coordinated control commands for each DC transformer node, including the following steps: The network control terminal collects real-time data on voltage distribution, load distribution, and voltage attenuation of the entire locomotive contact network and establishes a dynamic model of the locomotive contact network power supply conditions. The optimal voltage compensation amplitude for each DC transformer node is calculated based on the dynamic model of the locomotive overhead contact line power supply condition, and a voltage regulation reference value is generated.

6. A DC transformer for series connection of locomotive contact network according to claim 3, characterized in that, The secondary calibration of the output voltage includes the following steps: After the power automatic adjustment module's operating parameters are adjusted, real-time data of the output voltage is continuously collected, and the deviation value of the adjusted output voltage is calculated. The adjusted voltage deviation value is compared with a preset calibration threshold. If the adjusted voltage deviation value is greater than the preset calibration threshold, a secondary adjustment parameter is generated. The operating parameters of the automatic power adjustment module are corrected according to the secondary control parameters until the output voltage deviation is within the preset threshold. The data from the secondary calibration process is stored and analyzed to form a voltage regulation self-learning database, providing a reference for subsequent regulation of similar output voltage deviation scenarios.

7. A DC transformer for series connection of locomotive contact network according to claim 1, characterized in that, The process of forming the voltage regulation self-learning database includes the following steps: Record the output voltage deviation value of each secondary calibration, the operating parameters of the automatic power adjustment module, and the load current to form a voltage regulation self-learning database; The optimal voltage regulation parameters under different operating conditions were obtained by analyzing the voltage regulation self-learning database. When the same output voltage deviation value and operating condition are detected, the optimal voltage regulation parameter is directly called.

8. A DC transformer for series connection of locomotive contact network according to claim 1, characterized in that, The method of rapidly releasing electrical energy to support voltage during the start-up of a high-load overhead contact line includes the following steps: Real-time monitoring of the change rate of contact network voltage and load current; when the rate of increase of load current within a preset time window exceeds the start-up judgment threshold, it is predicted that a large load is connected. The real-time contact network voltage is compared with the discharge intervention threshold, which is set to 90%-95% of the rated voltage. When the contact network voltage is lower than the discharge intervention threshold and the load current continues to increase, the high load starting condition is confirmed. Immediately generate a power support start command to control the bidirectional DC / DC converter to operate in maximum power mode, and the supercapacitor energy storage unit to discharge rapidly, injecting compensation current into the contact network; Monitor the recovery of the contact network voltage in real time and dynamically adjust the discharge power to ensure that the contact network voltage recovers quickly to within ±2% of the rated value.

9. A DC transformer for series connection of locomotive contact network according to claim 1, characterized in that, The power support module performs charging and discharging control according to the contact network voltage status, including the following steps: The input DC voltage, output voltage, and load current of each section of the overhead contact line are monitored in real time using voltage and current acquisition components. The real-time monitored contact network voltage data is compared with the preset voltage threshold to determine the contact network voltage status. When the contact wire voltage is lower than the discharge intervention threshold and the load current is greater than the starting current threshold, it is determined to be a large load starting condition. A discharge control command is generated to control the supercapacitor energy storage unit to release electrical energy to the contact wire, supporting the contact wire voltage to recover to the rated value. When the contact network voltage recovers to the rated value and the stable duration reaches the preset exit delay, a power support exit command is generated to control the supercapacitor energy storage unit to stop discharging. When the contact network voltage is higher than the charging start threshold and the locomotive is detected to be in a downhill regenerative braking condition, a charging control command is generated to control the supercapacitor energy storage unit to receive feedback energy for charging and energy storage.

10. A DC transformer for series connection of locomotive contact network according to claim 1, characterized in that, The seamless switching of the main and bypass circuits according to the control command includes the following steps: The system receives real-time operating status data from the automatic power adjustment module to determine whether the automatic power adjustment module is in a fault or maintenance shutdown state. When the power automatic adjustment module is detected to be in a fault or maintenance shutdown state, the intelligent voltage regulation module sends a circuit switching command to the bypass switching module. The bypass switching module closes the bypass power supply circuit and disconnects the main power supply circuit according to the circuit switching command to achieve power supply switching; During bypass power supply, the bypass switching module continuously monitors the operating status data of the automatic power adjustment module; After detecting that the operating status data of the automatic power adjustment module has returned to normal, the intelligent voltage regulation module sends a circuit reset command; The bypass switching module closes the main power supply circuit, disconnects the bypass power supply circuit, and restores the normal power supply to the main circuit according to the circuit reset command. During the switching and reset process, the loop current and voltage data of the main circuit and bypass circuit are collected in real time.

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