An electromagnetic phase-shifting compensation type traction power supply new energy three-phase grid-connected system and a control method thereof

Abstract

The application discloses a new energy three-phase grid-connected system of electromagnetic phase-shifting compensation type traction power supply and a control method, and relates to the technical field of electrified railway new energy. The new energy three-phase power supply unit and the electromagnetic phase-shifting compensation unit are connected in parallel across the traction power supply two-phase circuit through two-phase alternating current ports. According to different actual working conditions and operation requirements of the traction side and the DC power supply side, the central control unit is used for energy management and coordinated control in different modes. The application can effectively solve the problems of the existing traction power supply new energy three-phase access technology, such as low utilization of new energy electric energy, inability of brake electric energy to be recycled across the phase, and difficulty in active compensation of negative sequence and reactive power and other power quality, and realizes full consumption of new energy, efficient utilization of brake energy, dynamic compensation of electromagnetic phase-shifting, comprehensive optimization of power quality, and improvement of the reliability and economy of the new energy grid-connected system.

Description

Technical Field

[0001] This invention belongs to the field of electrified railway new energy technology, and in particular relates to an electromagnetic phase-shifting compensation type traction power supply new energy three-phase grid-connected system and control method. Background Technology

[0002] In my country's electrified railway traction power supply systems, a phase-by-phase power supply system is generally adopted. To adapt to this unique characteristic, the mainstream existing traction power supply new energy integration application schemes include three-phase new energy access schemes, back-to-back new energy access power supply schemes, and cross-phase new energy access schemes. Among them, the invention patent "A Three-Phase Photovoltaic DC Side Energy Storage System and its Control Method for Electrified Railways" (application number: 201710962103.X) realizes the access of the photovoltaic power generation system to the traction side by utilizing a three-phase voltage source converter and port transformer, with the energy storage device connected to the photovoltaic DC side. Simultaneously, considering the characteristics of the traction load, a self-consumption surplus grid connection control strategy is designed to absorb photovoltaic power. The invention patent "An Integrated Conversion Device and Control Method for Photovoltaic Traction Power Supply Systems" (application number: 201611219102.8)... By connecting two single-phase quadrant converters in a two-phase traction power supply circuit, and integrating photovoltaic energy storage into the DC bus of the back-to-back inverter based on a back-to-back connection structure, the photovoltaic power consumption and comprehensive power quality compensation of traction power supply are realized. The invention patent "A Traction Power Supply Active Power Integration System and its Control Method" (application number: 202210393761.2) directly connects the DC power supply to the two-phase traction feeder through a single-phase AC / DC converter, and at the same time, combined with a reactive power compensation device and a harmonic compensation method, the effective access of renewable energy and energy storage is realized. Based on existing patents, it is clear that the outstanding engineering advantages of the three-phase grid connection scheme for new energy sources compared to back-to-back and cross-phase grid connection schemes are: the system structure is simple, the two-phase to three-phase matching transformers used are compatible with the mature three-phase grid connection technology for new energy sources, and no additional new grid connection devices need to be developed; under the same installed capacity of new energy sources, the number and capacity of transformers required by the three-phase grid connection scheme, the number of fully controlled power devices, and the module capacity required are significantly lower than those of the back-to-back grid connection scheme. At the same time, compared with the cross-phase grid connection scheme, it does not inject a large amount of reactive power into the traction side during active power transmission and transfer, thus avoiding deterioration of the power quality on the traction side.

[0003] However, existing three-phase access schemes for new energy sources cannot dynamically adjust the output power of two phases. This will cause the phenomenon of single-phase or three-phase power flow from new energy sources to the grid side under certain operating conditions. This is not allowed for the grid at present. In order to avoid power flow back, the utilization rate of new energy sources will be greatly sacrificed. At the same time, the two-phase regenerative braking power in the existing three-phase access schemes cannot be effectively recovered and utilized. Although it will not seriously deteriorate the power quality such as negative sequence on the grid side, it cannot optimize the power quality assessment indicators through active compensation. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes an electromagnetic phase-shift compensation-type traction power supply new energy three-phase grid-connected system and control method. This system effectively solves practical application problems existing in current traction power supply new energy three-phase access technologies, such as backfeeding and low utilization of new energy power, inability to recover and utilize braking energy across phases, and difficulty in actively compensating for power quality issues such as negative sequence reactive power. While ensuring system operational reliability and engineering economy, this system achieves full absorption of new energy, efficient utilization of braking energy, dynamic electromagnetic phase-shift compensation, and comprehensive optimization of power quality, thereby improving the reliability and economy of the new energy grid-connected system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: an electromagnetic phase-shifting compensation type traction power supply new energy three-phase grid-connected system, comprising: a new energy three-phase power supply unit NETU, an electromagnetic phase-shifting compensation unit EPCU, and a central control unit CCU; the new energy three-phase power supply unit NETU and the electromagnetic phase-shifting compensation unit EPCU are both connected to the a-phase and b-phase power supply arm circuits of the traction power supply system through AC port a1 and AC port b1, respectively. The central control unit (CCU) monitors the electrical quantities and operating status of the new energy three-phase power supply unit (NETU), the electromagnetic phase-shifting compensation unit (EPSCU), and the traction power supply system (TPSS) circuit in real time. Through the energy management and coordinated control of the central control unit (CCU), the various components of the system can match and execute the coordinated and optimized operation that integrates the functions of traction-side new energy power supply, regenerative braking energy utilization, electromagnetic phase-shifting dynamic compensation, and power quality management.

[0006] Furthermore, the new energy three-phase power supply unit NTU includes a two-phase-to-three-matching transformer TMT, a three-phase DC / AC converter TDA, an intermediate DC link DCL, and a DC power supply DS. The DC terminal of the three-phase DC / AC converter TDA is connected to the output terminal of the DC power supply DS via the intermediate DC link DCL. The AC terminal of the three-phase DC / AC converter TDA is connected to the three-phase low-voltage terminal of the two-phase-to-three-matching transformer TMT. The two-phase high-voltage terminals of the two-phase-to-three-matching transformer TMT are connected in parallel to the two-phase output ports of the electromagnetic phase-shifting compensation unit EPCU.

[0007] Furthermore, the DC source DS includes, but is not limited to, new energy power generation units, energy storage units, new energy energy storage units, or other DC sources and their different combinations; the two-phase-three-phase matching transformer TMT includes, but is not limited to, V-connected two-phase-three-phase transformers, impedance matching balance transformers, Scott-connected two-phase-three-phase transformers, cross-connected two-phase-three-phase transformers, or VX-connected two-phase-three-phase transformers.

[0008] Furthermore, the electromagnetic phase-shifting compensation unit (EPCU) includes a first phase-shifting transformer S-RPST1 and a second phase-shifting transformer S-RPST2. The input terminal of the first phase-shifting transformer S-RPST1 is connected to AC port a1, and the output terminal is connected to the circuit of the second phase-shifting transformer. The output terminal of the second phase-shifting transformer S-RPST2 is connected to AC port b1.

[0009] Furthermore, in the electromagnetic phase-shifting compensation unit EPCU, the rotor windings of the first phase-shifting transformer S-RPST1 and the second phase-shifting transformer S-RPST2 are connected in parallel, while the stator windings are connected in series. Specifically, the starting ends of the stator and rotor windings of the first phase-shifting transformer S-RPST1, and the starting end of the rotor winding of the second phase-shifting transformer S-RPST2, are all connected to AC port a1. The starting end of the stator winding of the second phase-shifting transformer S-RPST2 is connected in series with the ending end of the stator winding of the first phase-shifting transformer S-RPST1, and the ending end of the stator winding of the second phase-shifting transformer S-RPST2 is connected to AC port b1. The rotor shaft of the first phase-shifting transformer is connected to the first rotor drive device RDD1, and the rotor is driven by the first servo motor SM1 to shift the phase angle. α 1. Independent rotation achieves phase adjustment. The rotor shaft of the second phase-shifting transformer is connected to the second rotor drive device RDD2, and the rotor is driven by the second servo motor SM2 to shift the phase angle. α 2. Independent rotation achieves phase adjustment; the electromagnetic phase shift compensation unit (EPCU) adjusts the phase shift angle based on the control signal. α 1. α 2. Coordinated control allows for independent and continuous adjustment of the voltage phase and amplitude between the two AC output ports, thereby dynamically controlling the active and reactive power transferred between the two ports.

[0010] Furthermore, the new energy three-phase power supply unit NETU and the electromagnetic phase-shifting compensation unit EPCU are independent electrical access modules on the traction power supply two-phase circuit, and are not integrated and coupled at the output port within the system; the photovoltaic power generation unit PVU in the DC power supply DS is connected to the intermediate DC link DCL after being connected to the first DC / DC converter DD1, and the energy storage unit ESU is connected to the intermediate DC link DCL in parallel after being connected to the second DC / DC converter DD2, and together they interact with the traction side load for power exchange.

[0011] Furthermore, the power between AC port a1 and the a-phase traction power supply circuit undergoes bidirectional interaction, coordinated and controlled by the central control unit (CCU). The interacting power includes new energy power from the DC source DS, energy storage power, braking power from the a-phase traction power supply circuit, and bidirectional power from the AC port b1 side transferred across phases by the electromagnetic phase-shifting compensation unit (EPCU). Similarly, the power between AC port b1 and the b-phase traction power supply circuit undergoes bidirectional interaction, coordinated and controlled by the central control unit (CCU). The interacting power includes new energy power from the DC source DS, energy storage power, braking power from the b-phase traction power supply circuit, and bidirectional power from the AC port a1 side transferred across phases by the electromagnetic phase-shifting compensation unit (EPSCU). The EPSCU controls the bidirectional cross-phase transfer of power between AC ports a1 and b1 as needed, supporting the balance of active power on the traction side, reactive power compensation, and improvement of power quality on the grid side. The new energy three-phase power supply unit (NETU) controls the bidirectional transmission of power between the two-phase AC ports and the DC power supply DS.

[0012] On the other hand, based on the electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system, the present invention also provides a control method for the electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system, including the following steps: S1, collect real-time operating data of the traction side and each unit of the system; let the traction load power of phase a traction power supply circuit be... P aL The traction load power of phase b traction power supply circuit is P bL The active and reactive power output by the electromagnetic phase-shifting compensation unit EPCU to AC port a1 is: P aE and Q aE The active and reactive power output to AC port b1 is P bE and Q bE The new energy three-phase power supply unit NETU outputs power to AC port a1 as follows: P aN The output power to AC port b1 is P bN The DC power supply in the NETU three-phase power supply unit can output power of: P DS The allowable charging power in the DC unit is P CD Total active power of traction-side load P TL = P aL + P bL ; S2, based on different actual operating scenarios, the energy management layer in the central control unit (CCU) determines the system operating mode and matches it to execute modes one through four; when... P TL > P DS When >0 and the internal energy state of the DC power supply unit is normal, execute S3 mode one; when P DS > P TL When >0 and the internal energy state of the DC power supply unit is normal, execute S4 mode two; when P TL When the energy level is ≤0 and the internal energy state of the DC power supply unit is normal, execute S5 mode 3; when there is no excess new energy or energy storage energy inside the DC power supply unit, execute S6 mode 4. S3, Mode 1, when P TL > P DS >0, at this time the traction side load is in traction state, the DC power supply DS outputs new energy power at maximum power and reasonably outputs stored energy, the new energy three-phase power supply unit NTU will supply power to the two phases in a balanced manner to absorb the new energy, preferably The electromagnetic phase-shifting compensation unit (EPCU) balances the active power of the two phases of traction power supply, ensuring full absorption of new energy sources, cross-phase utilization of braking energy, and comprehensive improvement of power quality on the grid side. Preferably, ; S4, Mode 2, when P DS > P TL >0, at this time the traction side load is in traction state, and the DC power supply DS operates with limited power, that is The excess renewable energy in the DC power supply DS is internally stored and self-balanced. The renewable energy three-phase power supply unit NTU will supply energy to the two-phase system in a balanced manner to absorb the renewable energy. Preferably, The electromagnetic phase-shifting compensation unit (EPCU) balances the active power of the two phases of traction power supply, ensuring full absorption of new energy sources, cross-phase utilization of braking energy, and comprehensive improvement of power quality on the grid side. Preferably, ; S5, Mode 3, when P TL ≤0, at this time the traction side load is in a braking state, the DC power supply DS control does not transmit energy externally, and excess renewable energy is stored internally. At the same time, the traction side braking energy is recovered and reused according to the current allowable charging power in the DC power supply. Preferably The braking power recovered from two phases by the new energy three-phase power supply unit NTU is preferably... Then, the electromagnetic phase-shifting compensation unit (EPCU) balances the active power of the two phases of the traction power supply, ensuring the cross-phase transfer of braking energy, secondary recovery and utilization, and comprehensive improvement of power quality on the grid side. Preferably, ; S6, Mode 4: When there is no excess renewable energy or stored energy within the DC power supply unit, the energy storage unit in the DC power supply DS absorbs energy from the two-phase balance under traction-side braking dynamics. Preferably... Until the DC power supply DS energy state recovers to the set threshold state, then mode one, mode two, or mode three is executed according to the actual operating scenario. Simultaneously, the electromagnetic phase-shifting compensation unit (EPCU) can perform two-phase active power balancing to ensure power quality on the grid side. Preferably... ; S7 obtains the target power commands from the electromagnetic phase-shifting compensation unit EPCU and the new energy three-phase power supply unit NETU based on the current operating mode, and sends them to the system equipment execution layer by the central control unit CCU to control each unit to quickly respond to the demand commands and coordinate operation.

[0013] Furthermore, the electromagnetic phase-shifting compensation unit (EPCU) dynamically controls the magnitude and direction of the active and reactive power output to AC port a1 and AC port b1 based on the optimization objective. This supports active power balance and phase-by-phase reactive power compensation between the a-phase and b-phase traction power supply circuits, ensuring full absorption of new energy sources, efficient utilization of braking energy, and comprehensive optimization of power quality. The control process includes: In active power transfer control, the electromagnetic phase-shifting compensation unit (EPCU) outputs active power P to AC port a1 and AC port b1. aE and P bE Satisfy the power response relationship: ; Among them, the voltage vector of the traction power supply circuit of phase a is used as the reference voltage. U The amplitude of the feeder voltage in the traction power supply circuit is given by δ0, and the phase difference between the two phase voltages is given by δ0. R and X These are the equivalent resistance and reactance of the electromagnetic phase-shifting compensation unit (EPCU), respectively. U c θ represents the amplitude of the compensation voltage input into the electromagnetic phase-shifting compensation unit EPCU, and θ represents the phase of the compensation voltage. Compensation voltage amplitude U c The phase θ of the compensation voltage is an independent controllable variable, subject to the phase shift angle of the first and second phase-shifting transformers. α 1 and α2. Coordinated Control: Based on the required active power compensation amount obtained in the S1~S5 energy management process, the electromagnetic phase-shifting compensation unit (EPCU) coordinates the control of the servo motor state by setting up, but not limited to, compensation current control, phase angle setpoint calculation, phase angle coordinated speed control, and flexible loop control, so as to achieve coordinated operation of the two phase-shifting transformers under different modes. In reactive power transfer control, the electromagnetic phase-shifting compensation unit (EPCU) outputs active power Q to AC port a1 and AC port b1. aE and Q bE Satisfy the power response relationship: ; Two-phase reactive power compensation is affected by the power factor measured on the grid side. PF Constraints, when measuring power factor PF < When setting the threshold, the optimization objective of the Electromagnetic Phase Shift Compensation Unit (EPCU) is primarily focused on phase-by-phase reactive power compensation to ensure the metered power factor. PF ≥ Set threshold; when the power factor is measured PF When the set threshold is reached, the optimization objective of the electromagnetic phase-shifting compensation unit (EPCU) is mainly based on the balance of two-phase active power, improving energy utilization and mitigating negative sequence issues, and ensuring that the voltage imbalance on the grid side meets the grid connection requirements.

[0014] Furthermore, the new energy three-phase power supply unit (NETU) dynamically controls the magnitude and direction of active and reactive power output to AC ports a1 and b1 based on optimization objectives; the new energy three-phase power supply unit (NETU) outputs power to two-phase AC ports in a balanced manner without affecting the negative sequence problem on the grid side; the three-phase DC / AC converter (TDA) adopts control methods including, but not limited to, indirect current control methods achieved through amplitude and / or phase control, direct current control methods that track grid voltage by controlling output current, control methods based on αβ transformation of stationary coordinate system, control methods based on dq transformation of synchronous rotating coordinate system, or direct power control methods based on instantaneous power feedback, to support the new energy three-phase power supply unit (NETU) in quickly responding to target commands and operating reliably and efficiently.

[0015] The beneficial effects of adopting this technical solution are: This invention proposes an electromagnetic phase-shift compensation-type traction power supply new energy three-phase grid-connected system. Compared with conventional new energy access schemes, it has engineering advantages such as simple system structure, mature technology, and no need to develop additional new grid-connected devices. While ensuring system reliability and engineering economy, it can effectively solve practical application problems existing in the current traction power supply new energy three-phase access technology, such as the backfeeding and low utilization rate of new energy power, the inability to recover and utilize braking energy across phases, and the difficulty in actively compensating for power quality issues such as negative sequence reactive power. It realizes full absorption of new energy, efficient utilization of braking energy, electromagnetic phase-shift dynamic compensation, and comprehensive optimization of power quality, thereby improving the reliability and economy of the new energy grid-connected system.

[0016] This invention proposes a control method for a three-phase grid-connected traction power supply system for new energy sources with electromagnetic phase-shift compensation. In the scenario of traction power supply integrating new energy sources, it can fully leverage the continuous dynamic adjustment of the magnitude and direction of active and reactive power output from the two-phase AC ports by the electromagnetic phase-shift compensation unit, ensuring reasonable multi-directional interaction of new energy power, energy storage energy, and traction power supply circuit power. At the same time, based on the different actual operating conditions and operational requirements of the traction side and the DC power supply side, the proposed control method can control the system units to match and execute different optimization objectives under the switching of operating modes, supporting the safe, stable, and efficient operation of the system. Attached Figure Description

[0017] Figure 1 This is a structural diagram of a three-phase grid-connected traction power supply system for new energy sources with electromagnetic phase-shift compensation according to the present invention; Figure 2 This is a schematic diagram of the main circuit wiring of an electromagnetic phase-shifting compensation unit in an embodiment of the present invention; Figure 3 This is a schematic diagram of the second structure of the electromagnetic phase-shifting compensation type traction power supply new energy three-phase grid-connected system in an embodiment of the present invention; Figure 4 This is a schematic diagram of a typical power transmission path in the system of this invention. Figure 5 This is a flowchart of a control method for an electromagnetic phase-shifting compensation type traction power supply new energy three-phase grid-connected system according to the present invention; Figure 6 This is a schematic diagram of a system power reference direction in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to the accompanying drawings.

[0019] In this embodiment, see Figure 1As shown, this invention proposes an electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system, including: new energy three-phase power supply unit NETU, electromagnetic phase-shift compensation unit EPCU and central control unit CCU; the new energy three-phase power supply unit NETU and electromagnetic phase-shift compensation unit EPCU are both connected to the a-phase and b-phase power supply arm circuits of the traction power supply system through AC port a1 and AC port b1, respectively. The central control unit (CCU) monitors the electrical quantities and operating status of the new energy three-phase power supply unit (NETU), the electromagnetic phase-shifting compensation unit (EPSCU), and the traction power supply system (TPSS) circuit in real time. Through the energy management and coordinated control of the central control unit (CCU), the various components of the system can match and execute the coordinated and optimized operation that integrates the functions of traction-side new energy power supply, regenerative braking energy utilization, electromagnetic phase-shifting dynamic compensation, and power quality management.

[0020] As an optimized embodiment of the above, the new energy three-phase power supply unit NTU includes a two-phase-to-three-matching transformer TMT, a three-phase DC / AC converter TDA, an intermediate DC link DCL, and a DC power supply DS. The DC terminal of the three-phase DC / AC converter TDA is connected to the output terminal of the DC power supply DS via the intermediate DC link DCL. The AC terminal of the three-phase DC / AC converter TDA is connected to the three-phase low-voltage terminal of the two-phase-to-three-matching transformer TMT. The two-phase high-voltage terminal of the two-phase-to-three-matching transformer TMT is connected in parallel to the two-phase output port of the electromagnetic phase-shifting compensation unit EPCU.

[0021] Preferably, the DC source DS includes, but is not limited to, new energy power generation units, energy storage units, new energy storage units, or other DC sources and their different combinations; the two-phase-to-three-phase matching transformer TMT includes, but is not limited to, V-connected two-phase-to-three-phase transformers, impedance matching balance transformers, Scott-connected two-phase-to-three-phase transformers, cross-connected two-phase-to-three-phase transformers, or VX-connected two-phase-to-three-phase transformers.

[0022] As an optimization of the above embodiments, such as Figure 2 As shown, the electromagnetic phase-shifting compensation unit EPCU includes a first phase-shifting transformer S-RPST1 and a second phase-shifting transformer S-RPST2. The input terminal of the first phase-shifting transformer S-RPST1 is connected to AC port a1, and the output terminal is connected to the circuit of the second phase-shifting transformer. The output terminal of the second phase-shifting transformer S-RPST2 is connected to AC port b1.

[0023] Preferably, in the electromagnetic phase-shifting compensation unit EPCU, the rotor windings of the first phase-shifting transformer S-RPST1 and the second phase-shifting transformer S-RPST2 are connected in parallel, while the stator windings are connected in series. Specifically, the starting ends of the stator and rotor windings of the first phase-shifting transformer S-RPST1, and the starting end of the rotor winding of the second phase-shifting transformer S-RPST2, are all connected to AC port a1. The starting end of the stator winding of the second phase-shifting transformer S-RPST2 is connected in series with the ending end of the stator winding of the first phase-shifting transformer S-RPST1, and the ending end of the stator winding of the second phase-shifting transformer S-RPST2 is connected to AC port b1. The rotor shaft of the first phase-shifting transformer is connected to the first rotor drive device RDD1, and the rotor is driven by the first servo motor SM1 to shift the phase angle. α 1. Independent rotation achieves phase adjustment. The rotor shaft of the second phase-shifting transformer is connected to the second rotor drive device RDD2, and the rotor is driven by the second servo motor SM2 to shift the phase angle. α 2. Independent rotation achieves phase adjustment; the electromagnetic phase shift compensation unit (EPCU) adjusts the phase shift angle based on the control signal. α 1. α 2. Coordinated control allows for independent and continuous adjustment of the voltage phase and amplitude between the two AC output ports, thereby dynamically controlling the active and reactive power transferred between the two ports.

[0024] As an optimization of the above embodiments, such as Figure 3 As shown, in the electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system EPTPS, the new energy three-phase power supply unit NETU and the electromagnetic phase-shift compensation unit EPCU can be used as independent electrical access modules on the traction power supply two-phase circuit, without being integrated and coupled at the output port inside the system; the photovoltaic power generation unit PVU in the DC power supply DS is connected to the intermediate DC link DCL after being connected to the first DC / DC converter DD1, and the energy storage unit ESU is connected to the optional second DC / DC converter DD2 and then connected to the intermediate DC link DCL in parallel, so as to jointly interact with the traction side load.

[0025] As an optimization of the above embodiments, such as Figure 4The diagram illustrates a typical power transmission path in the system. In the electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system EPTPS, the power between AC port a1 and the a-phase traction power supply circuit undergoes bidirectional interaction, coordinated and managed by the central control unit (CCU). The interacting power includes new energy power and energy storage power in the DC source DS, braking power of the a-phase traction power supply circuit, and bidirectional power on the AC port b1 side transferred across phases by the electromagnetic phase-shift compensation unit (EPCU). The power between AC port b1 and the b-phase traction power supply circuit also undergoes bidirectional interaction, coordinated and managed by the central control unit (CCU). The CU coordinates and controls the interactive power, which includes new energy power, energy storage power, braking power of the b-phase traction power supply circuit in the DC source DS, and bidirectional power on the AC port a1 side transferred by the electromagnetic phase-shifting compensation unit EPSCU across phases. The electromagnetic phase-shifting compensation unit EPSCU can control the power to be transferred bidirectionally across phases on demand between AC port a1 and AC port b1, supporting the balance of active power on the traction side, reactive power compensation, and improvement of power quality on the grid side. The new energy three-phase power supply unit NTU controls the bidirectional transmission of power between the two-phase AC port and the DC power supply DS.

[0026] To facilitate the implementation of the system of this invention, based on the same inventive concept, such as Figure 5 As shown, the present invention also provides a control method for an electromagnetic phase-shifting compensated traction power supply new energy three-phase grid-connected system, comprising the following steps: S1, collect real-time operating data of the traction side and each unit of the system; let the traction load power of phase a traction power supply circuit be... P aL The traction load power of phase b traction power supply circuit is P bL The active and reactive power output by the electromagnetic phase-shifting compensation unit EPCU to AC port a1 is: P aE and Q aE The active and reactive power output to AC port b1 is P bE and Q bE The new energy three-phase power supply unit NETU outputs power to AC port a1 as follows: P aN The output power to AC port b1 is P bN The DC power supply in the NETU three-phase power supply unit can output power of: P DS The allowable charging power in the DC unit is P CD Total active power of traction-side load P TL = PaL + P bL ; S2, based on different actual operating scenarios, the energy management layer in the central control unit (CCU) determines the system operating mode and matches it to execute modes one through four; when... P TL > P DS When >0 and the internal energy state of the DC power supply unit is normal, execute S3 mode one; when P DS > P TL When >0 and the internal energy state of the DC power supply unit is normal, execute S4 mode two; when P TL When the energy level is ≤0 and the internal energy state of the DC power supply unit is normal, execute S5 mode 3; when there is no excess new energy or energy storage energy inside the DC power supply unit, execute S6 mode 4. S3, Mode 1, when P TL > P DS >0, at this time the traction side load is in traction state, the DC power supply DS outputs new energy power at maximum power and reasonably outputs stored energy, the new energy three-phase power supply unit NTU will supply power to the two phases in a balanced manner to absorb the new energy, preferably The electromagnetic phase-shifting compensation unit (EPCU) balances the active power of the two phases of traction power supply, ensuring full absorption of new energy sources, cross-phase utilization of braking energy, and comprehensive improvement of power quality on the grid side. Preferably, ; S4, Mode 2, when P DS > P TL >0, at this time the traction side load is in traction state, and the DC power supply DS operates with limited power, that is The excess renewable energy in the DC power supply DS is internally stored and self-balanced. The renewable energy three-phase power supply unit NTU will supply energy to the two-phase system in a balanced manner to absorb the renewable energy. Preferably, The electromagnetic phase-shifting compensation unit (EPCU) balances the active power of the two phases of traction power supply, ensuring full absorption of new energy sources, cross-phase utilization of braking energy, and comprehensive improvement of power quality on the grid side. Preferably, ; S5, Mode 3, when P TL≤0, at this time the traction side load is in a braking state, the DC power supply DS control does not transmit energy externally, and excess renewable energy is stored internally. At the same time, the traction side braking energy is recovered and reused according to the current allowable charging power in the DC power supply. Preferably The braking power recovered from two phases by the new energy three-phase power supply unit NTU is preferably... Then, the electromagnetic phase-shifting compensation unit (EPCU) balances the active power of the two phases of the traction power supply, ensuring the cross-phase transfer of braking energy, secondary recovery and utilization, and comprehensive improvement of power quality on the grid side. Preferably, ; S6, Mode 4: When there is no excess renewable energy or stored energy within the DC power supply unit, the energy storage unit in the DC power supply DS absorbs energy from the two-phase balance under traction-side braking dynamics. Preferably... Until the DC power supply DS energy state recovers to the set threshold state, then mode one, mode two, or mode three is executed according to the actual operating scenario. Simultaneously, the electromagnetic phase-shifting compensation unit (EPCU) can perform two-phase active power balancing to ensure power quality on the grid side. Preferably... ; S7 obtains the target power commands from the electromagnetic phase-shifting compensation unit EPCU and the new energy three-phase power supply unit NETU based on the current operating mode, and sends them to the system equipment execution layer by the central control unit CCU to control each unit to quickly respond to the demand commands and coordinate operation.

[0027] As an optimization of the above embodiment, the electromagnetic phase-shifting compensation unit (EPCU) dynamically controls the magnitude and direction of the active and reactive power output to AC port a1 and AC port b1 according to the optimization objective. This supports active power balance and phase-by-phase reactive power compensation between the a-phase and b-phase traction power supply circuits, ensuring full absorption of new energy sources, efficient utilization of braking energy, and comprehensive optimization of power quality. The control process includes: In active power transfer control, the electromagnetic phase-shifting compensation unit (EPCU) outputs active power P to AC port a1 and AC port b1. aE and P bE Satisfy the power response relationship: ; Among them, the voltage vector of the traction power supply circuit of phase a is used as the reference voltage. U The amplitude of the feeder voltage in the traction power supply circuit is given by δ0, and the phase difference between the two phase voltages is given by δ0. R and X These are the equivalent resistance and reactance of the electromagnetic phase-shifting compensation unit (EPCU), respectively. U c θ represents the amplitude of the compensation voltage input into the electromagnetic phase-shifting compensation unit EPCU, and θ represents the phase of the compensation voltage.

[0028] Compensation voltage amplitudeU c The phase θ of the compensation voltage is an independent controllable variable, subject to the phase shift angle of the first and second phase-shifting transformers. α 1 and α 2. Coordinated Control: Based on the required active power compensation amount obtained in the S1~S5 energy management process, the electromagnetic phase-shifting compensation unit (EPCU) coordinates the control of the servo motor state by setting up, but not limited to, compensation current control, phase angle setpoint calculation, phase angle coordinated speed control, and flexible loop control, so as to achieve coordinated operation of the two phase-shifting transformers under different modes. In reactive power transfer control, the electromagnetic phase-shifting compensation unit (EPCU) outputs active power Q to AC port a1 and AC port b1. aE and Q bE Satisfy the power response relationship: ; Two-phase reactive power compensation is affected by the power factor measured on the grid side. PF Constraints, when measuring power factor PF < When setting the threshold, the optimization objective of the Electromagnetic Phase Shift Compensation Unit (EPCU) is primarily focused on phase-by-phase reactive power compensation to ensure the metered power factor. PF ≥ Set threshold; when the power factor is measured PF When the threshold value is greater than or equal to the set threshold, the optimization objective of the Electromagnetic Phase Shift Compensation Unit (EPCU) is primarily focused on balancing the active power of both phases, improving energy utilization, mitigating negative sequence issues, and ensuring that the voltage imbalance on the grid side meets grid connection requirements. The set threshold value is selected based on the national standard for grid-connected power quality requirements.

[0029] As an optimization of the above embodiments, the new energy three-phase power supply unit (NETU) dynamically controls the magnitude and direction of active and reactive power output to AC ports a1 and b1 according to the optimization target; the new energy three-phase power supply unit (NETU) outputs power to the two-phase AC ports in a balanced manner without affecting the negative sequence problem on the grid side; the three-phase DC / AC converter (TDA) adopts control methods including but not limited to indirect current control methods achieved through amplitude and / or phase control, direct current control methods that track grid voltage by controlling the output current, control methods based on the αβ transformation of the stationary coordinate system, control methods based on the dq transformation of the synchronous rotating coordinate system, or direct power control methods based on instantaneous power feedback, according to the issued power command, to support the new energy three-phase power supply unit (NETU) in quickly responding to target commands and operating reliably and efficiently.

[0030] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An electromagnetic phase-shifting compensation type traction power supply new energy three-phase grid-connected system, characterized in that, include: The new energy three-phase power supply unit NETU, the electromagnetic phase-shifting compensation unit EPCU, and the central control unit CCU; the new energy three-phase power supply unit NETU and the electromagnetic phase-shifting compensation unit EPCU are both connected to the a-phase and b-phase power supply arm circuits of the traction power supply system through AC port a1 and AC port b1, respectively. The central control unit (CCU) monitors the electrical quantities and operating status of the new energy three-phase power supply unit (NETU), the electromagnetic phase-shifting compensation unit (EPSCU), and the traction power supply system (TPSS) circuit in real time. Through the energy management and coordinated control of the central control unit (CCU), the various components of the system can match and execute the coordinated and optimized operation that integrates the functions of traction-side new energy power supply, regenerative braking energy utilization, electromagnetic phase-shifting dynamic compensation, and power quality management.

2. The electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system according to claim 1, characterized in that, The new energy three-phase power supply unit NTU includes a two-phase-to-three-matching transformer TMT, a three-phase DC / AC converter TDA, an intermediate DC link DCL, and a DC power supply DS. The DC terminal of the three-phase DC / AC converter TDA is connected to the output terminal of the DC power supply DS via the intermediate DC link DCL. The AC terminal of the three-phase DC / AC converter TDA is connected to the three-phase low-voltage terminal of the two-phase-to-three-matching transformer TMT. The two-phase high-voltage terminals of the two-phase-to-three-matching transformer TMT are connected in parallel to the two-phase output ports of the electromagnetic phase-shifting compensation unit EPCU.

3. The electromagnetic phase-shifting compensation type traction power supply new energy three-phase grid-connected system according to claim 2, characterized in that, The DC source DS includes, but is not limited to, new energy power generation units, energy storage units, new energy energy storage units, or other DC sources and their different combinations; the two-phase-three-phase matching transformer TMT includes, but is not limited to, V-connected two-phase-three-phase transformers, impedance matching balance transformers, Scott-connected two-phase-three-phase transformers, cross-connected two-phase-three-phase transformers, or VX-connected two-phase-three-phase transformers.

4. The electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system according to claim 1, characterized in that, The electromagnetic phase-shifting compensation unit (EPCU) includes a first phase-shifting transformer S-RPST1 and a second phase-shifting transformer S-RPST2. The input terminal of the first phase-shifting transformer S-RPST1 is connected to AC port a1, and the output terminal is connected to the circuit of the second phase-shifting transformer. The output terminal of the second phase-shifting transformer S-RPST2 is connected to AC port b1.

5. The electromagnetic phase-shifting compensation type traction power supply new energy three-phase grid-connected system according to claim 4, characterized in that, In the electromagnetic phase-shifting compensation unit EPCU, the rotor windings of the first phase-shifting transformer S-RPST1 and the second phase-shifting transformer S-RPST2 are connected in parallel, while the stator windings are connected in series. The starting ends of the stator and rotor windings of the first phase-shifting transformer S-RPST1, and the starting end of the rotor winding of the second phase-shifting transformer S-RPST2, are all connected to AC port a1. The starting end of the stator winding of the second phase-shifting transformer S-RPST2 is connected in series with the ending end of the stator winding of the first phase-shifting transformer S-RPST1, and the ending end of the stator winding of the second phase-shifting transformer S-RPST2 is connected to AC port b1. The rotor shaft of the first phase-shifting transformer is connected to the first rotor drive device RDD1, and the rotor is driven by the first servo motor SM1 to shift the phase angle. α 1. Independent rotation achieves phase adjustment. The rotor shaft of the second phase-shifting transformer is connected to the second rotor drive device RDD2, and the rotor is driven by the second servo motor SM2 to shift the phase angle. α 2. Independent rotation achieves phase adjustment; the electromagnetic phase shift compensation unit (EPCU) adjusts the phase shift angle based on the control signal. α 1. α 2. Coordinated control allows for independent and continuous adjustment of the voltage phase and amplitude between the two AC output ports, thereby dynamically controlling the active and reactive power transferred between the two ports.

6. The electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system according to claim 1, characterized in that, The new energy three-phase power supply unit NETU and the electromagnetic phase shift compensation unit EPCU are independent electrical access modules on the traction power supply two-phase circuit, and are not integrated and coupled at the output port inside the system; the photovoltaic power generation unit PVU in the DC power supply DS is connected to the intermediate DC link DCL after being connected to the first DC / DC converter DD1, and the energy storage unit ESU is connected to the intermediate DC link DCL in parallel after being connected to the second DC / DC converter DD2, and together they interact with the traction side load for power.

7. A three-phase grid-connected traction power supply system for new energy sources with electromagnetic phase-shift compensation as described in any one of claims 1-6, characterized in that, The power between AC port a1 and the a-phase traction power supply circuit is bidirectionally exchanged, coordinated and controlled by the central control unit (CCU). The exchanged power includes new energy power from the DC source DS, energy storage power, braking power from the a-phase traction power supply circuit, and bidirectional power from the AC port b1 side transferred by the electromagnetic phase-shifting compensation unit (EPCU) across phases. The power between AC port b1 and the b-phase traction power supply circuit is also bidirectionally exchanged, coordinated and controlled by the central control unit (CCU). The exchanged power includes new energy power from the DC source DS, energy storage power, braking power from the b-phase traction power supply circuit, and bidirectional power from the AC port a1 side transferred by the electromagnetic phase-shifting compensation unit (EPSCU) across phases. The EPSCU can control the power to be transferred bidirectionally across phases between AC ports a1 and b1 as needed, supporting the balance of active power on the traction side, reactive power compensation, and improvement of power quality on the grid side. The new energy three-phase power supply unit (NETU) controls the bidirectional transmission of power between the two-phase AC ports and the DC power supply DS.

8. A control method for an electromagnetic phase-shifting compensated traction power supply new energy three-phase grid-connected system, characterized in that, The new energy three-phase grid-connected system based on electromagnetic phase-shift compensation traction power supply includes: a new energy three-phase power supply unit (NETU), an electromagnetic phase-shift compensation unit (EPCU), and a central control unit (CCU); the new energy three-phase power supply unit (NETU) and the electromagnetic phase-shift compensation unit (EPCU) are both connected to the a-phase and b-phase power supply arm circuits of the traction power supply system through AC port a1 and AC port b1, respectively; the central control unit (CCU) is connected to the internal controllers of each unit and performs bidirectional information flow interaction. Including the following steps: S1, collect real-time operating data of the traction side and each unit of the system; let the traction load power of phase a traction power supply circuit be... P aL The traction load power of phase b traction power supply circuit is P bL The active and reactive power output by the electromagnetic phase-shifting compensation unit EPCU to AC port a1 is: P aE and Q aE The active and reactive power output to AC port b1 is P bE and Q bE The new energy three-phase power supply unit NETU outputs power to AC port a1 as follows: P aN The output power to AC port b1 is P bN The DC power supply in the NETU three-phase power supply unit can output power of: P DS The allowable charging power in the DC unit is P CD Total active power of traction-side load P TL = P aL + P bL ; S2, based on different actual operating scenarios, the energy management layer in the central control unit (CCU) determines the system operating mode and matches it to execute modes one through four; when... P TL > P DS When >0 and the internal energy state of the DC power supply unit is normal, execute S3 mode one; when P DS > P TL When >0 and the internal energy state of the DC power supply unit is normal, execute S4 mode two; when P TL When the energy level is ≤0 and the internal energy state of the DC power supply unit is normal, execute S5 mode 3; when there is no excess new energy or energy storage energy inside the DC power supply unit, execute S6 mode 4. S3, Mode 1, when P TL > P DS >0, at this time the traction side load is in traction state, the DC power supply DS outputs new energy power at maximum power and reasonably outputs stored energy, the new energy three-phase power supply unit NTU will supply power to the two phases in a balanced manner to absorb new energy; the electromagnetic phase shift compensation unit EPCU balances the active power of the two phases of traction power supply to ensure full absorption of new energy, cross-phase mutual supplementation of braking power and comprehensive improvement of power quality on the grid side. S4, Mode 2, when P DS > P TL >0, at this time the traction side load is in traction state, the DC power supply DS operates with limited power, that is, P DS =P TL The excess renewable energy in the DC power supply DS is internally stored and self-balanced. The renewable energy three-phase power supply unit NTU will supply energy to the two phases in a balanced manner to absorb renewable energy. The electromagnetic phase-shifting compensation unit EPCU balances the active power of the two phases of traction power supply, ensuring full absorption of renewable energy, cross-phase utilization of braking energy, and comprehensive improvement of power quality on the grid side. S5, Mode 3, when P TL ≤0, at this time the traction side load is in a braking dynamic, the DC power supply DS control does not transmit energy to the outside, the excess new energy power is stored internally, and the traction side braking power is recovered and utilized according to the current allowable charging power in the DC power supply; the new energy three-phase power supply unit NETU recovers the braking power from two phases, and then the electromagnetic phase shift compensation unit EPCU balances the active power of the two phases of traction power supply, ensuring the cross-phase transfer of braking power, secondary recovery and utilization, and comprehensive improvement of the power quality of the grid side; S6, Mode 4: When there is no excess new energy or energy storage in the DC power supply unit, the energy storage unit in the DC power supply DS absorbs energy from the two-phase balance under the dynamic control of the traction side. After the energy state of the DC power supply DS is restored to the set threshold state, Mode 1, Mode 2, or Mode 3 will be executed according to the actual operating scenario. At the same time, the electromagnetic phase shift compensation unit EPCU can perform two-phase active power balance to ensure the power quality of the grid side. S7 obtains the target power commands from the electromagnetic phase-shifting compensation unit EPCU and the new energy three-phase power supply unit NETU based on the current operating mode, and sends them to the system equipment execution layer by the central control unit CCU to control each unit to quickly respond to the demand commands and coordinate operation.

9. The control method for an electromagnetic phase-shifting compensated traction power supply new energy three-phase grid-connected system according to claim 8, characterized in that, The electromagnetic phase-shifting compensation unit (EPCU) dynamically controls the magnitude and direction of active and reactive power output to AC port a1 and AC port b1 according to the optimization target. This supports active power balance and phase-by-phase reactive power compensation between the a-phase and b-phase traction power supply circuits, ensuring full absorption of new energy sources, efficient utilization of braking energy, and comprehensive optimization of power quality. The control process includes: In active power transfer control, the electromagnetic phase-shifting compensation unit (EPCU) outputs active power P to AC port a1 and AC port b1. aE and P bE Satisfy the power response relationship: ； Among them, the voltage vector of the traction power supply circuit of phase a is used as the reference voltage. U The amplitude of the feeder voltage in the traction power supply circuit is given by δ0, and the phase difference between the two phase voltages is given by δ0. R and X These are the equivalent resistance and reactance of the electromagnetic phase-shifting compensation unit (EPCU), respectively. U c θ represents the amplitude of the compensation voltage input into the electromagnetic phase-shifting compensation unit EPCU, and θ represents the phase of the compensation voltage. Compensation voltage amplitude U c The phase θ of the compensation voltage is an independent controllable variable, subject to the phase shift angle of the first and second phase-shifting transformers. α 1 and α 2. Coordinated Control: Based on the required active power compensation amount obtained in the S1~S5 energy management process, the electromagnetic phase-shifting compensation unit (EPCU) coordinates the control of the servo motor state by setting up, but not limited to, compensation current control, phase angle setpoint calculation, phase angle coordinated speed control, and flexible loop control, so as to achieve coordinated operation of the two phase-shifting transformers under different modes. In reactive power transfer control, the electromagnetic phase-shifting compensation unit (EPCU) outputs active power Q to AC port a1 and AC port b1. aE and Q bE Satisfy the power response relationship: ； Two-phase reactive power compensation is affected by the power factor measured on the grid side. PF Constraints, when measuring power factor PF < When setting the threshold, the optimization objective of the Electromagnetic Phase Shift Compensation Unit (EPCU) is primarily focused on phase-by-phase reactive power compensation to ensure the metered power factor. PF ≥ Set threshold; when the power factor is measured PF When the set threshold is reached, the optimization objective of the electromagnetic phase-shifting compensation unit (EPCU) is mainly based on the balance of two-phase active power, improving energy utilization and negative sequence, and ensuring that the voltage imbalance on the grid side meets the grid connection requirements.

10. The control method for an electromagnetic phase-shift compensation type traction power supply new energy three-phase grid-connected system according to claim 8, characterized in that, The new energy three-phase power supply unit (NETU) dynamically controls the magnitude and direction of active and reactive power output to AC ports a1 and b1 according to the optimization target. The new energy three-phase power supply unit (NETU) outputs power to the two-phase AC ports in a balanced manner without affecting the negative sequence problem on the grid side. The three-phase DC / AC converter (TDA) adopts control methods including but not limited to indirect current control methods achieved through amplitude and / or phase control, direct current control methods that track the grid voltage by controlling the output current, control methods based on the αβ transformation of the stationary coordinate system, control methods based on the dq transformation of the synchronous rotating coordinate system, or direct power control methods based on instantaneous power feedback, according to the issued power command, to support the new energy three-phase power supply unit (NETU) in quickly responding to target commands and operating reliably and efficiently.

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