Double-dragging system and control method and device thereof

Abstract

The invention provides a twin trawling system and a control method and device thereof, and relates to the technical field of power electronic control. The twin trawling system comprises a first power converter and a second power converter; the control method of the twin trawling system comprises the following steps: acquiring the output power of the first power converter and the second power converter in real time; determining a current charging and discharging power difference according to the current output power of the first power converter and the second power converter; when the current charging and discharging power difference is within a preset difference value range, the current output power of the first power converter and the current output power of the second power converter are adjusted to be initial power; when the current charging and discharging power difference is larger than the upper limit value of the preset difference value range, the current output power of the first power converter and the current output power of the second power converter are adjusted to be 0. According to the invention, by dynamically adjusting the current output power of the first power converter and the second power converter, unbalance of charging and discharging power in the twin-trawling system is avoided, and the stability and flexibility of the twin-trawling system are improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power electronic control technology, and in particular to a towing system and a control method and device thereof. Background Art

[0002] In the fields of microgrids, energy storage systems, and power conversion systems (PCS), towing control is a key testing and energy management technology used to achieve power exchange between power devices to verify system performance and improve operational efficiency.

[0003] Existing tandem systems typically use two sets of power converters, each connected to a corresponding set of energy storage modules. Fixed power commands control the charging of one set of power converters while the other discharges. This allows power exchange between the two energy storage modules, or between the energy storage modules and the grid via a transformer.

[0004] However, the power distribution of the power converters in the aforementioned towing system is based on a preset fixed value, which remains unchanged during the operation of the towing system. Therefore, the towing system cannot dynamically adjust the operating power according to the real-time operating status of the power converters, resulting in the power difference between the two groups of power converters possibly exceeding the expected range, causing system instability or transformer overload. In addition, the lack of a real-time adjustment mechanism makes it difficult for the towing system to adapt to changes in the test environment, such as the power limit of the energy storage module or grid fluctuations, which in turn affects the stability of the towing system and the safety of the equipment. Summary of the Invention

[0005] The present invention provides a towing system and a control method and device thereof, which avoids charging and discharging power imbalance in the towing system by dynamically adjusting the current output power of two groups of power converters, and improves the stability and flexibility of the towing system.

[0006] A first aspect of the present invention provides a control method for a towing system, wherein the towing system includes a first power converter and a second power converter connected in series. The control method for the towing system includes:

[0007] S1: acquiring, in real time, the output power of the first power converter and the output power of the second power converter when the first power converter and the second power converter are charging and discharging;

[0008] S2: determining a current charge-discharge power difference according to a current output power of the first power converter and a current output power of the second power converter;

[0009] S3: When the current charge-discharge power difference is within a preset difference range, adjusting the current output power of the first power converter and the current output power of the second power converter to initial power;

[0010] S4: When the current charge-discharge power difference is greater than an upper limit of the preset difference range, adjusting the current output power of the first power converter and the current output power of the second power converter to 0.

[0011] Optionally, before S1, the method further includes:

[0012] S0: When starting the first power converter and the second power converter for charging and discharging, adjusting the initial output power of the first power converter to the initial power, and adjusting the initial output power of the second power converter to the initial power.

[0013] Optionally, the S0 includes:

[0014] S01: When starting the first power converter and the second power converter for charging and discharging, the current initial output power of the first power converter and the current initial output power of the second power converter are increased with a first preset power adjustment gradient until the current initial output power of the first power converter and the current initial output power of the second power converter are both the initial power.

[0015] Optionally, the S3 includes:

[0016] S31: When the current charge and discharge power difference is within the preset difference range, the current output power of the first power converter and the current output power of the second power converter are respectively adjusted with a second preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both the initial power.

[0017] Optionally, the S31 includes:

[0018] S311: When the current charge-discharge power difference is within the preset difference range, determine the larger of the current output power of the first power converter and the current output power of the second power converter as the first output power, and the smaller of the current output power as the second output power, and determine the power converter having the first output power of the first power converter and the second power converter as the high-power converter, and determine the power converter having the second output power of the first power converter and the second power converter as the low-power converter;

[0019] S312: reducing the first output power until the power difference between the current output power of the high-power converter and the second output power reaches a lower limit of the preset difference range;

[0020] S313: Regulating the first output power and the second output power respectively with the second preset power regulation gradient until the current output power of the high-power converter and the current output power of the low-power converter are both the initial power.

[0021] Optionally, the S4 includes:

[0022] S41: When the current charge and discharge power difference is greater than the upper limit value of the preset difference range, the current output power of the first power converter and the current output power of the second power converter are reduced with a third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0023] Optionally, the S41 includes:

[0024] S411: When the current charge-discharge power difference is greater than an upper limit of the preset difference range, determining the larger of the current output power of the first power converter and the current output power of the second power converter as a first output power, and the smaller of the current output power of the first power converter and the second power converter as a second output power, and determining the power converter having the first output power of the first power converter and the second power converter as a high-power converter, and determining the power converter having the second output power of the first power converter and the second power converter as a low-power converter;

[0025] S412: reducing the first output power by the third preset power adjustment gradient;

[0026] S413: reducing the second output power by the third preset power adjustment gradient;

[0027] S414: When the current output power of the low-power converter is greater than 0, return to executing S412 to S413 until the current output power of the low-power converter is 0;

[0028] S415: When the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, return to execute S413 until the current output power of the high-power converter is 0.

[0029] Optionally, the towing system further includes a first energy storage module and a second energy storage module; the first power converter is connected to the first energy storage module; the second power converter is connected to the second energy storage module; and the control method of the towing system further includes:

[0030] S5: Acquire operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module in real time; the operating condition information includes operating voltage, operating current, and operating temperature;

[0031] S6: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, reducing the current output power of the first power converter and the current output power of the second power converter by a fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0032] Optionally, the S6 includes:

[0033] S61: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, determining the larger of the current output power of the first power converter and the current output power of the second power converter as a first output power, and the smaller of the current output power of the first power converter and the second power converter as a second output power, and determining the power converter having the first output power among the first power converter and the second power converter as a high-power converter, and determining the power converter having the second output power among the first power converter and the second power converter as a low-power converter;

[0034] S62: reducing the first output power at the fourth preset power adjustment gradient until the current output power of the high-power converter reaches the second output power;

[0035] S63: Reduce the current output power of the first power converter and the current output power of the second power converter by the fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0036] Optionally, the towing system further includes a transformer; the AC end of the first power converter and the AC end of the second power converter are both electrically connected to the primary side of the transformer, and the secondary side of the transformer is electrically connected to the mains power grid; one of the first power converter and the second power converter is a charging power converter, and the other is a discharging power converter; the control method of the towing system further includes:

[0037] S7: When the output power of the discharge power converter is greater than the output power of the charge power converter, controlling part of the output power of the discharge power converter to be converted by the transformer and then provided to the commercial power grid;

[0038] S8: Obtaining a grid power value outputted by the discharge power converter to the commercial power grid;

[0039] S9: When the grid power value is greater than a preset reverse flow threshold, obtaining a power difference between the grid power value and the preset reverse flow threshold;

[0040] S10: reducing the output power of the discharge power converter by the power difference.

[0041] A second aspect of the present invention provides a control device for a towing system, the towing system including a first power converter and a second power converter connected in series; the control device for the towing system includes:

[0042] an output power acquisition module, configured to acquire the output power of the first power converter and the output power of the second power converter in real time when the first power converter and the second power converter are charging and discharging;

[0043] a current charge-discharge power difference determining module, configured to determine a current charge-discharge power difference according to a current output power of the first power converter and a current output power of the second power converter;

[0044] a first current output power adjustment module, configured to adjust the current output power of the first power converter and the current output power of the second power converter to initial power when the current charge-discharge power difference is within a preset difference range;

[0045] The second current output power adjustment module is configured to adjust the current output power of the first power converter and the current output power of the second power converter to 0 when the current charge-discharge power difference is greater than an upper limit of the preset difference range.

[0046] Optionally, a third aspect of the present invention provides a towing system, the towing system comprising: a controller, and a first power converter and a second power converter connected in series;

[0047] The controller is connected to the first power converter and the second power converter respectively, and is used to execute the control method of the towing system as described above.

[0048] Optionally, the towing system further includes a transformer;

[0049] The AC end of the first power converter and the AC end of the second power converter are both electrically connected to the primary side of the transformer, and the secondary side of the transformer is electrically connected to the mains power grid;

[0050] One of the first power converter and the second power converter is a charging power converter, and the other is a discharging power converter.

[0051] The technical solution of the present invention realizes real-time monitoring of the operating status of the towing system by acquiring the output power of the first power converter and the output power of the second power converter in real time, and determines the current charge-discharge power difference based on the current output power of the first power converter and the current output power of the second power converter, providing a data basis for dynamically adjusting the current output power of the first power converter and the current output power of the second power converter. When the current charge-discharge power difference is within a preset difference range, the current output power of the first power converter and the current output power of the second power converter are adjusted to the initial power, so that the current charge-discharge power difference is reduced to below the lower limit of the preset difference range, thereby avoiding the imbalance of charge and discharge power in the towing system, ensuring the safe operation of the transformer, and improving the stability and flexibility of the towing system. At the same time, the towing system can be operated according to the preset initial charge-discharge power, ensuring the accurate operation of the towing system and improving the operating efficiency of the towing system. In addition, by adjusting the current output power of the first power converter and the current output power of the second power converter to 0 when the current charge and discharge power difference is greater than the upper limit of the preset difference range, the power transmission of the towing system can be stopped in time when there is a serious imbalance in the charge and discharge power of the towing system, thereby effectively preventing transformer overload, fluctuations in the mains power grid and damage to the energy storage module, ensuring the safe operation of the towing system and various equipment, and at the same time improving the maintenance efficiency of the towing system and enhancing the reliability and stability of the towing system.

[0052] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0054] Figure 1 This is a structural diagram of a towing system provided by the present invention;

[0055] Figure 2 It is a flow chart of a control method of a towing system provided by the present invention;

[0056] Figure 3 1 is a flow chart of another control method for a towing system provided by the present invention;

[0057] Figure 4 1 is a flow chart of another control method for a towing system provided by the present invention;

[0058] Figure 5 1 is a flow chart of another control method for a towing system provided by the present invention;

[0059] Figure 6 It is a structural schematic diagram of a control device for a towing system provided by the present invention. DETAILED DESCRIPTION

[0060] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0061] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0062] Figure 1 This is a structural diagram of a towing system provided by the present invention, such as Figure 1 As shown, the towing system includes: a first power converter 11 and a second power converter 12 connected in series.

[0063] Among them, the first power converter 11 and the second power converter 12 constitute a power conversion system, and the first power converter 11 and the second power converter 12 are connected in series to form a string power conversion system for realizing bidirectional power conversion between DC and AC. The first power converter 11 can be connected to the first energy storage module 21, and the second power converter 12 can be connected to the second energy storage module 22 to realize power transmission between the first energy storage module 21 and the second energy storage module 22. The first energy storage module 21 and the second energy storage module 22 can be specifically understood as energy storage devices for storing and releasing electrical energy. Exemplarily, the first energy storage module 21 and the second energy storage module 22 may include a battery pack and a battery management system. The battery management system is used to monitor parameters such as the state of charge, voltage, current and temperature of the battery pack in real time to ensure the charging and discharging performance and safety of the battery pack.

[0064] Specifically, the control signal transmission terminal 111 of the first power converter 11 is communicatively connected to the control signal input terminal 211 of the first energy storage module 21, so that the first power converter 11 can control the first energy storage module 21 to charge or discharge according to its output power; the control signal transmission terminal 121 of the second power converter 12 is communicatively connected to the control signal input terminal 221 of the second energy storage module 22, so that the second power converter 12 can control the second energy storage module 22 to charge or discharge according to its output power.

[0065] One of the first power converter 11 and the second power converter 12 is a charging power converter, and the other is a discharging power converter. The AC end 113 of the first power converter 11 is electrically connected to the AC end 123 of the second power converter 12, so that the towing system can achieve power transmission between the first energy storage module 21 and the second energy storage module 22 through DC-AC conversion or AC-DC conversion by the first power converter 11 and the second power converter 12. Unless otherwise specified, the embodiments of the present invention are described by taking the first power converter 11 as a discharging power converter and the second power converter 12 as a charging power converter as an example to exemplify the technical solutions of the present invention.

[0066] The first power converter 11 can control the first energy storage module 21 to discharge at the output power based on the output power of the first power converter 11, so that the DC signal stored in the first energy storage module 21 can be transmitted to the DC terminal 112 of the first power converter 11 via the charge and discharge terminal 212. The DC signal is converted from DC to AC by the first power converter 11 into an AC signal, and then transmitted to the AC terminal 123 of the second power converter 12 via the AC terminal 113 of the first power converter 11. The second power converter 12 converts the received AC signal into a DC signal through AC-DC conversion, and transmits it to the charge and discharge terminal 222 of the second energy storage module 22 via the DC terminal 122 of the second power converter 12 at the output power of the second power converter 12, thereby enabling the second energy storage module 22 to store the electrical energy output by the first energy storage module 21.

[0067] In addition, the towing system also includes a transformer 3, the AC end 113 of the first power converter 11 and the AC end 123 of the second power converter 12 are both electrically connected to the primary side 31 of the transformer 3, and the secondary side 32 of the transformer 3 is electrically connected to the mains power grid 4.

[0068] It is understood that during operation of the tandem system, there may be a difference between the output power of the first power converter 11 and the output power of the second power converter 12, resulting in an imbalance in the charge and discharge power of the first energy storage module 21 and the second energy storage module 22. To ensure the operational stability of the tandem system, it is necessary to transmit AC signals between the utility grid 4 and the tandem system via the transformer 3 to ensure a balance in the charge and discharge power of the first energy storage module 21 and the second energy storage module 22. Exemplarily, when the discharge power of the first power converter 11 is greater than the charging power of the second power converter 12, the excess AC signal of the first power converter 11 can be output to the primary side 31 of the transformer 3 through the AC end 113 of the first power converter 11, and transmitted to the mains grid 4 through the secondary side 32 of the transformer 3, and the mains grid 4 absorbs the excess AC signal output by the first energy storage module 21 to maintain the power balance of the towing system; when the charging power of the second power converter 12 is greater than the discharge power of the first power converter 11, the mains grid 4 can provide electrical energy to the secondary side 32 of the transformer 3, and transmit it to the AC end 123 of the second power converter 12 through the primary side 31 of the transformer 3, so as to supplement the electrical energy required by the second energy storage module 22 through the AC signal provided by the mains grid 4 to maintain the power balance of the towing system.

[0069] It is also understandable that when the power difference between the output power of the first power converter 11 and the output power of the second power converter 12 is too large, the AC signal transmitted through the transformer 3 may exceed its rated power, potentially causing transformer 3 to overload and overheat, and causing instability in the towing system. Therefore, it is necessary to dynamically adjust the output power of the first power converter 11 and the output power of the second power converter 12 to maintain power balance in the towing system, ensure the safe operation of the transformer, and thus improve the stability and flexibility of the towing system.

[0070] The towing system further includes a controller 5 connected to the first power converter 11 and the second power converter 12, respectively. Specifically, the control signal output terminal 51 of the controller 5 is communicatively connected to the control signal transmission terminal 111 of the first power converter 11 and the control signal transmission terminal 121 of the second power converter 12, respectively. Exemplarily, the controller 5 may include an Energy Management System (EMS), which may communicate with the first power converter 11 and the second power converter 12 via the Modbus TCP protocol. It is understood that the controller 5 in the towing system can execute the control method of the towing system provided in the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not fully described in this embodiment, please refer to the control method of the towing system described in the embodiment below.

[0071] Figure 2 This is a flow chart of a control method for a towing system provided by the present invention. This method can be used to control the towing system of the above embodiment, and this method can be executed by a control device for the towing system. This device can be implemented by software and / or hardware and can generally be integrated into a controller. Figure 2 As shown, the control method of the towing system may include:

[0072] S1: When the first power converter and the second power converter are charging and discharging, the output power of the first power converter and the output power of the second power converter are acquired in real time.

[0073] Exemplarily, when the first power converter is a discharging power converter and the second power converter is a charging power converter, the output power of the first power converter can be specifically understood as the output power of the AC end of the first power converter, and the first power converter is used to control the first energy storage module to discharge with the output power of the first power converter; the output power of the second power converter can be specifically understood as the output power of the DC end of the second power converter, and the second power converter is used to control the second energy storage module to charge with the output power of the second power converter, so that the second energy storage module can store the electrical energy output by the first energy storage module.

[0074] Specifically, the controller can obtain the output current of the first power converter and the second power converter in real time through the current signal acquisition module, and obtain the output voltage of the first power converter and the second power converter in real time through the voltage signal acquisition module, so as to realize real-time acquisition of the output power of the first power converter and the output power of the second power converter, thereby enabling real-time monitoring of the operating status of the towing system, and providing a data basis for subsequent determination of the power difference between the current output power of the first power converter and the current output power of the second power converter, and dynamic adjustment of the current output power of the first power converter and the current output power of the second power converter.

[0075] S2: Determine a current charge-discharge power difference according to the current output power of the first power converter and the current output power of the second power converter.

[0076] Among them, the charge-discharge power difference can be specifically understood as the absolute value of the difference between the current discharge power of the first power converter and the current charging power of the second power converter. For example, when the current discharge power of the first power converter is greater than the current charging power of the second power converter, the charge-discharge power difference can be specifically understood as the difference between the current discharge power of the first power converter and the current charging power of the second power converter; when the current discharge power of the first power converter is less than the current charging power of the second power converter, the charge-discharge power difference can be specifically understood as the difference between the current charging power of the second power converter and the current discharge power of the first power converter; when the current discharge power of the first power converter is equal to the current charging power of the second power converter, the charge-discharge power difference is 0.

[0077] Specifically, after the controller obtains the output power of the first power converter and the output power of the second power converter in real time, it can also determine the current charge-discharge power difference based on the current output power of the first power converter and the current output power of the second power converter. The current charge-discharge power difference reflects the degree of imbalance in power transmission between the first energy storage module and the second energy storage module in the towing system. This charge-discharge power difference may be caused by differences in the state of charge of the energy storage modules, limitations of the battery management system, or losses in the towing system.

[0078] It is also understandable that when the current charge-discharge power difference is too large, it may cause transformer overload and overheating, and cause instability in the towing system. Therefore, it is necessary to obtain the output power of the first power converter and the output power of the second power converter in real time through the controller, and determine the current charge-discharge power difference, which provides a data basis for the subsequent dynamic adjustment of the current output power of the first power converter and the current output power of the second power converter, thereby improving the stability and flexibility of the towing system. In addition, the maximum number of verifications of the current charge-discharge power difference can be preset in the controller. For example, the maximum number of verifications can be 60 times to reduce the computational burden of the controller and reduce the energy consumption of the towing system.

[0079] S3: When the current charge and discharge power difference is within a preset difference range, adjusting the current output power of the first power converter and the current output power of the second power converter to initial power.

[0080] The preset difference range can be specifically understood as the acceptable range of the current charge-discharge power difference. The preset difference range includes a lower limit and an upper limit. For example, the lower limit of the preset difference range can be 150kW, and the upper limit of the preset difference range can be 350kW. It can be understood that when the current charge-discharge power difference is less than the lower limit of the preset difference range, it means that the output power of the first power converter and the output power of the second power converter are close to or have reached a balanced state. At this time, the towing system operates stably and there is no need to adjust the output power of the first power converter and the output power of the second power converter. When the current charge-discharge power difference is greater than or equal to the lower limit of the preset difference range, and the current charge-discharge power difference is less than or equal to the upper limit of the preset difference range, it means that the current charge-discharge power difference is small but there is still power imbalance. It is necessary to dynamically adjust the output power of the first power converter and the output power of the second power converter to reduce the current charge-discharge power difference to below the lower limit of the preset difference range. In addition, the preset difference range may include a dead zone range, which is close to the lower limit value of the preset difference range. When the current charge and discharge power difference is within the dead zone range, it can be considered that the current charge and discharge power difference is small enough, and the controller will not trigger the adjustment of the current output power of the first power converter and the current output power of the second power converter to avoid frequent or unnecessary power changes, so as to maintain smooth power transmission of the towing system.

[0081] Specifically, after the controller determines the current charge and discharge power of the first power converter and the second power converter, it can compare the current charge and discharge power with a preset difference range, and when it is determined that the current charge and discharge power difference is within the preset difference range, it can adjust the current output power of the first power converter and the current output power of the second power converter to the initial power. By adjusting the current output power of the first power converter and the current output power of the second power converter to the initial power, the imbalance of the charge and discharge power of the towing system is avoided, the safe operation of the transformer is ensured, and the stability and flexibility of the towing system is improved. At the same time, the towing system can operate according to the preset initial charge and discharge power, thereby ensuring the accurate operation of the towing system and improving the operating efficiency of the towing system.

[0082] S4: When the current charge and discharge power difference is greater than an upper limit of a preset difference range, adjusting the current output power of the first power converter and the current output power of the second power converter to 0.

[0083] Specifically, when the controller determines that the current charge and discharge power difference is greater than the upper limit value of the preset difference range, it indicates that the difference between the current output power of the first power converter and the current output power of the second power converter is too large, and there is a serious imbalance in the charge and discharge power of the towing system. Therefore, the controller can adjust the current output power of the first power converter and the current output power of the second power converter to 0 to ensure the safety of the towing system.

[0084] It is understandable that when the difference between the current output power of the first power converter and the current output power of the second power converter is too large, the electric energy that needs to be transmitted through the transformer may exceed its rated power, which may cause transformer overload, overheating or equipment damage, and may cause power shock to the mains power grid, thereby affecting the safety of the mains power grid. At the same time, excessive current charge and discharge power may cause the first energy storage module to over-discharge or the second energy storage module to overcharge, triggering battery management system protection, and even damaging the battery pack. Therefore, by adjusting the current output power of the first power converter and the current output power of the second power converter to 0 through the controller, the power transmission to the towing system can be stopped in time, thereby effectively preventing transformer overload, mains power grid fluctuations and damage to the energy storage module, extending the service life of the transformer and energy storage module, and ensuring the safe operation of the towing system and various equipment. In addition, after adjusting the current output power of the first power converter and the current output power of the second power converter to 0, the controller can control the first power converter and the second power converter to stop running, providing a safe maintenance environment for operators, facilitating timely troubleshooting of abnormal operating conditions of the towing system, thereby improving the maintenance efficiency of the towing system and enhancing the reliability and stability of the towing system.

[0085] In this embodiment, the output power of the first power converter and the output power of the second power converter are obtained in real time to achieve real-time monitoring of the operating status of the towing system. The current charge-discharge power difference is determined based on the current output power of the first power converter and the current output power of the second power converter, providing a data basis for dynamically adjusting the current output power of the first power converter and the current output power of the second power converter. When the current charge-discharge power difference is within a preset difference range, the current output power of the first power converter and the current output power of the second power converter are adjusted to the initial power so that the current charge-discharge power difference is reduced to below the lower limit of the preset difference range. This avoids charge-discharge power imbalance in the towing system, ensures the safe operation of the transformer, and improves the stability and flexibility of the towing system. At the same time, it enables the towing system to operate according to the preset initial charge-discharge power, ensuring the accurate operation of the towing system and improving the operating efficiency of the towing system. In addition, by adjusting the current output power of the first power converter and the current output power of the second power converter to 0 when the current charge and discharge power difference is greater than the upper limit of the preset difference range, the power transmission of the towing system can be stopped in time when there is a serious imbalance in the charge and discharge power of the towing system, thereby effectively preventing transformer overload, fluctuations in the mains power grid and damage to the energy storage module, ensuring the safe operation of the towing system and various equipment, and at the same time improving the maintenance efficiency of the towing system and enhancing the reliability and stability of the towing system.

[0086] Optional, Figure 3 FIG. 1 is a flow chart of another control method for a towing system provided by the present invention. Figure 3 As shown, before S1, it also includes:

[0087] S0: When starting the first power converter and the second power converter for charging and discharging, the initial output power of the first power converter is adjusted to the initial power, and the initial output power of the second power converter is adjusted to the initial power.

[0088] Specifically, when the first power converter and the second power converter are started to charge and discharge to achieve power transmission between the first energy storage module and the second energy storage module, the controller can adjust the initial output power of the first power converter to the initial power, and adjust the initial output power of the second power converter to the initial power. The initial power can be understood as the target output power of the first power converter and the second power converter pre-set according to actual needs. For example, the initial power can be automatically distributed to the first power converter and the second power converter by the controller, or can be manually set through a display module of the controller, such as a display screen.

[0089] It is understood that by setting the initial powers of the first power converter and the second power converter to the same value, so that the initial charge and discharge power difference between the first power converter and the second power converter is 0, the charge and discharge power balance of the towing system is ensured, thereby minimizing the transmission burden of the transformer and the replenishment demand of the mains power grid, and ensuring that the first energy storage module and the second energy storage module are charged and discharged at the expected power. It is also understood that, under the premise of ensuring that the initial charge and discharge power difference between the first power converter and the second power converter is less than the lower limit of the preset difference range, the initial powers of the first power converter and the second power converter can also be slightly different, so that the towing system can adapt to the different charge and discharge power requirements of the first energy storage module and the second energy storage module, thereby improving the flexibility and robustness of the towing system.

[0090] Optionally, S0 includes:

[0091] S01: When starting the first power converter and the second power converter for charging and discharging, the current initial output power of the first power converter and the current initial output power of the second power converter are increased with a first preset power adjustment gradient until the current initial output power of the first power converter and the current initial output power of the second power converter are both initial powers.

[0092] Specifically, when the initial output power of the first power converter is adjusted to the initial power by the controller, and the output power of the second power converter is adjusted to the initial power, the initial output power of the first power converter and the initial output power of the second power converter can be increased with a first preset power adjustment gradient, so that the initial output power of the first power converter and the initial output power of the second power converter can be adjusted to the initial power. The first preset power adjustment gradient can be specifically understood as a fixed power increment for a single adjustment when the initial output power of the first power converter and the second power converter is adjusted by the controller. The first preset power adjustment gradient can be determined according to actual needs, and the present invention does not make specific limitations on this. For example, the first preset power adjustment gradient can be 200kW.

[0093] The controller first increases the initial output power of the first power converter and the second power converter with a first preset power adjustment gradient, so that the initial output power of the first power converter is increased by one first preset power adjustment gradient, and the initial output power of the second power converter is increased by one first preset power adjustment gradient. The adjustment order of the initial output power of the first power converter and the second power converter can be determined according to actual needs and is not specifically limited in the present invention. For example, the current initial output power of the first power converter is increased to 200kW, and the current initial output power of the second power converter is increased to 200kW. Afterwards, the controller will obtain the current initial output power of the first power converter and the second power converter. When the current initial output powers of the first power converter and the second power converter are correctly increased by a gradient, and the current initial output powers of the first power converter and the second power converter have not reached the initial power, the controller will continue to increase the initial output power of the first power converter and the initial output power of the second power converter with the first preset power adjustment gradient, so that the initial output power of the first power converter is increased by a first preset power adjustment gradient again, and the initial output power of the second power converter is increased by a first preset power adjustment gradient again. For example, the current initial output power of the first power converter is increased to 400kW, and the current initial output power of the second power converter is increased to 400kW, until the current initial output powers of the first power converter and the second power converter are increased. After the rate reaches the initial power, the adjustment of the initial output power of the first power converter and the second power converter is stopped; when at least one of the current initial output powers of the first power converter and the second power converter fails to correctly increase a first preset power adjustment gradient, it indicates that there may be a fault in the towing system at this time, and the controller will control the current initial output power of the power converter whose current initial output power fails to correctly increase a first preset power adjustment gradient to fall back to the previous gradient value. For example, when the current initial output power of the first power converter fails to correctly increase from 200kW to 400kW, the controller will control the current initial output power of the first power converter to fall back to 200kW, and stop further adjustment of the initial output power of the first power converter and the second power converter to prevent further expansion of the fault and provide conditions for inspection and maintenance of the towing system.

[0094] It is understandable that the controller ensures that the difference between the current initial output powers of the first power converter and the second power converter always remains within a small range by first controlling the initial output power of the first power converter to increase by a first preset power adjustment gradient, and then controlling the initial output power of the second power converter to increase by a first preset power adjustment gradient, through an alternating adjustment method. That is, the difference between the current initial output powers of the first power converter and the second power converter does not exceed a first preset power adjustment gradient, thereby avoiding an imbalance in the charge and discharge power in the towing system and improving the stability and flexibility of the towing system. At the same time, by adjusting the initial output power of the first power converter and the second power converter with the first preset power adjustment gradient, the smooth operation of the power transmission between the first energy storage module and the second energy storage module is ensured, avoiding failure of the first energy storage module and the second energy storage module due to sudden changes in charge and discharge power, and extending the service life of the energy storage modules.

[0095] It is also understandable that when increasing the initial output power of the first power converter and the initial output power of the second power converter with the first preset power adjustment gradient, the initial output power of the discharge power converter can be adjusted first, and then the initial output power of the charging converter can be adjusted, so as to ensure sufficient power supply by first controlling the energy storage module to discharge through the discharge power converter, and provide stable power input for the subsequent charging of the energy storage module through the charging power converter, which conforms to the flow logic of power transmission. This avoids the situation where the initial output power of the discharge power converter is insufficient when the initial output power of the charging converter is first increased, which may lead to an increase in the burden on the mains power grid and voltage fluctuations in the mains power grid, thereby ensuring the stability of power transmission in the tow system.

[0096] Optionally, S3 includes:

[0097] S31: When the current charge and discharge power difference is within a preset difference range, the current output power of the first power converter and the current output power of the second power converter are respectively adjusted with a second preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both initial powers.

[0098] Specifically, when the current charge-discharge power difference is within the preset difference range, it means that the current charge-discharge power difference is small but there is still power imbalance. The controller can adjust the current output power of the first power converter and the current output power of the second power converter respectively with the second preset power adjustment gradient, until the current output power of the first power converter and the current output power of the second power converter are both the initial power, so that the current charge-discharge power difference is reduced to below the lower limit of the preset difference range, and at the same time, the towing system can operate according to the preset initial charge-discharge power, thereby ensuring the accurate operation of the towing system and improving the operating efficiency of the towing system. The second preset power adjustment gradient can be specifically understood as a fixed power increment for a single adjustment when adjusting the current output power of the first power converter and the second power converter through the controller. The second preset power adjustment gradient and the first preset adjustment gradient can be the same or different, and the present invention does not make specific limitations on this. For example, the second preset power adjustment gradient can be 200kW.

[0099] Optionally, S31 includes:

[0100] S311: When the current charge and discharge power difference is within a preset difference range, the larger one of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, and the smaller one is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as the high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as the low-power converter.

[0101] Specifically, when the current output power of the first power converter and the current output power of the second power converter are adjusted to the initial power through the controller, the current output power of the first power converter and the current output power of the second power converter are first compared, so that the larger one of the current output power of the first power converter and the current output power of the second power converter can be determined as the first output power, and the smaller one can be determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter can be determined as the high-power converter, and the power converter with the second output power among the first power converter and the second power converter can be determined as the low-power converter, thereby providing a basis for the subsequent adjustment process.

[0102] S312: Reduce the first output power until the power difference between the current output power of the high-power converter and the second output power reaches a lower limit of a preset difference range.

[0103] Specifically, after determining the first output power and the second output power, the controller will reduce the first output power until the power difference between the current output power of the high-power converter and the second output power reaches the lower limit of the preset difference range, so that the power difference between the current output power of the high-power converter and the current output power of the small-power converter is smaller, thereby avoiding the imbalance of charging and discharging power in the towing system, thereby reducing the transmission burden of the transformer and the demand for replenishment of the mains power grid, and ensuring smooth power transmission of the towing system.

[0104] S313: Regulate the first output power and the second output power respectively using a second preset power regulation gradient until the current output power of the high-power converter and the current output power of the low-power converter are both initial powers.

[0105] Specifically, after the power difference between the current output power of the high-power converter and the second output power reaches the lower limit of the preset difference range, the controller can adjust the first output power and the second output power respectively with the second preset power adjustment gradient, so that the first output power is adjusted by a second preset power adjustment gradient, and the second output power is adjusted by a second preset power adjustment gradient. The adjustment order of the first output power and the second output power can be determined according to actual needs. The present invention does not limit this. For example, when the first output power is greater than the initial power and the second output power is less than the initial power, the first output power is reduced by 200kW and the second output power is increased by 200kW. Afterwards, the controller will obtain the current output power of the high-power converter and the current output power of the low-power converter. When the current output power of the high-power converter does not reach the initial power and the current output power of the low-power converter does not reach the initial power, the controller will continue to adjust the first output power and the second output power respectively with the second preset power adjustment gradient, so that the first output power is adjusted again by a second preset power adjustment gradient, and the second output power is adjusted again by a second preset power adjustment gradient. For example, the first output power is reduced by 200kW again and the second output power is increased by 200kW again. After the current output power of the high-power converter and the current output power of the low-power converter are both the initial power, the adjustment of the first output power and the second output power is stopped. It can be understood that when the current output power of the high-power converter does not reach the initial power and the current output power of the low-power converter does not reach the initial power, the controller will only adjust the current output power of the power converter that has not reached the initial power with the second preset power adjustment gradient.

[0106] Furthermore, after the current output power of the high-power converter and the current output power of the low-power converter reach the initial power, the controller will continue to monitor the first output power and the second output power. This allows for dynamic adjustment of the current output power of the first power converter and the current output power of the second power converter when the current charge-discharge power difference is greater than or equal to the lower limit of a preset difference range. This allows for timely detection and avoidance of charge-discharge power imbalances in the traction system, reducing the transmission burden on the transformer and the need to supplement the utility grid, thereby improving the stability and flexibility of the traction system.

[0107] It can be understood that the controller adopts an alternating adjustment method of controlling the first output power to adjust a second preset power adjustment gradient, and then controlling the second output power to adjust a second preset power adjustment gradient, thereby ensuring that in the process of adjusting the first output power and the second output power, the difference between the current output powers of the first power converter and the second power converter is always maintained at the lower limit of the preset difference range, thereby avoiding the imbalance of charging and discharging power in the towing system and improving the stability and flexibility of the towing system.

[0108] Optionally, S4 includes:

[0109] S41: When the current charge and discharge power difference is greater than the upper limit value of the preset difference range, the current output power of the first power converter and the current output power of the second power converter are reduced by a third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0110] Specifically, when the current charge-discharge power difference is greater than the upper limit of the preset difference range, it indicates that the difference between the current output power of the first power converter and the current output power of the second power converter is too large, and there is a serious imbalance in the charge-discharge power of the towing system. The controller can reduce the current output power of the first power converter and the current output power of the second power converter by a third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0, so as to promptly stop the power transmission in the towing system, thereby effectively preventing transformer overload, mains power grid fluctuations and damage to the energy storage module, extending the service life of the transformer and energy storage module, and ensuring the safe operation of the towing system and various devices. The third preset power adjustment gradient can be specifically understood as a fixed power increment for a single adjustment when the current output power of the first power converter and the second power converter is adjusted by the controller. The third preset power adjustment gradient and the first preset adjustment gradient can be the same or different, and the present invention does not specifically limit this. For example, the third preset power adjustment gradient can be 200kW.

[0111] Optionally, the S41 includes:

[0112] S411: When the current charge and discharge power difference is greater than the upper limit value of the preset difference range, the larger one of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, and the smaller one is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as the high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as the low-power converter.

[0113] Specifically, when the current output power of the first power converter and the current output power of the second power converter are adjusted to 0 by the controller, the current output power of the first power converter and the current output power of the second power converter are first compared, so that the larger one of the current output power of the first power converter and the current output power of the second power converter can be determined as the first output power, and the smaller one can be determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter can be determined as the high-power converter, and the power converter with the second output power among the first power converter and the second power converter can be determined as the low-power converter, thereby providing a basis for the subsequent adjustment process.

[0114] S412: Decrease the first output power with a third preset power adjustment gradient.

[0115] Specifically, after determining the first output power and the second output power, the controller will reduce the first output power with a third preset power adjustment gradient.

[0116] S413: Decrease the second output power with a third preset power adjustment gradient.

[0117] Specifically, after reducing the first output power with the second preset power adjustment gradient, the second output power is reduced with the third preset power adjustment to achieve preferential adjustment of the output power of the large-power converter to reduce a third preset power adjustment gradient, and then adjust the output power of the small-power converter to reduce a third preset power adjustment gradient, so as to reduce the current charge-discharge power difference by preferentially adjusting the output power of the large-power converter, and avoid the continued increase of the current charge-discharge power difference caused by preferential adjustment of the output power of the small-power converter, so as to alleviate the transmission burden of the transformer and the demand for supplementation of the mains power grid. For example, after the first output power is reduced by 200kW, the second output power is adjusted to reduce 200kW.

[0118] S414: When the current output power of the low-power converter is greater than 0, the process returns to S412 to S413 until the current output power of the low-power converter is 0.

[0119] Specifically, the controller will obtain the current output power of the small-power converter and the current output power of the high-power converter. When the current output power of the small-power converter is greater than 0, it indicates that the current output powers of the small-power converter and the high-power converter have not been reduced to 0. The controller will continue to reduce the first output power with a third preset power adjustment gradient, and after reducing the first output power with a second preset power adjustment gradient, continue to reduce the second output power with the third preset power adjustment, so as to achieve priority adjustment of the output power of the high-power converter to reduce a third preset power adjustment gradient again, and then adjust the output power of the small-power converter again to reduce a third preset power adjustment gradient. For example, after the first output power is reduced by 200kW again, the second output power is adjusted to reduce by 200kW again until the current output power of the small-power converter is 0, and the adjustment of the first output power is stopped.

[0120] S415 : When the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, return to S413 and execute until the current output power of the high-power converter is 0.

[0121] Specifically, when the current output power of the small-power converter is 0 and the current output power of the large-power converter is greater than 0, it indicates that the current output power of the small-power converter has been reduced to 0, while the current output power of the large-power converter has not yet been reduced to 0. At this time, only the current output power of the large-power converter needs to be adjusted, and the controller will reduce the second output power at a third preset power adjustment gradient until the current output power of the large-power converter is 0. In addition, after adjusting the current output power of the first power converter and the current output power of the second power converter to 0, the controller can control the first power converter and the second power converter to stop operating, providing a safe maintenance environment for operators and facilitating timely troubleshooting of abnormal operating conditions of the towing system, thereby improving the maintenance efficiency of the towing system and enhancing the reliability and stability of the towing system.

[0122] It can be understood that the controller adopts an alternating adjustment method of controlling the first output power to adjust a third preset power adjustment gradient and then controlling the second output power to adjust a third preset power adjustment gradient. This ensures that during the process of adjusting the first output power and the second output power, the difference between the current output powers of the first power converter and the second power converter will not further increase. At the same time, it avoids failure of the first energy storage module and the second energy storage module due to sudden changes in charging and discharging power, thereby extending the service life of the energy storage module.

[0123] Optional, Figure 4 FIG. 1 is a flow chart of another control method for a towing system provided by the present invention. Figure 4 As shown, the control method of the towing system also includes:

[0124] S5: Acquire operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module in real time.

[0125] The operating condition information includes operating voltage, operating current and operating temperature.

[0126] Specifically, the controller can also obtain the operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module in real time. The operating condition information includes the operating voltage, the operating current, and the operating temperature. The operating voltage can be specifically understood as the AC or DC terminal voltage of the first power converter and the second power converter and the battery pack voltage of the first energy storage module and the second energy storage module; the operating current can be specifically understood as the input current or output current of the first power converter and the second power converter and the charge and discharge current of the first energy storage module and the second energy storage module; the operating temperature can be specifically understood as the temperature of the heat sink in the first power converter and the second power converter and the battery pack temperature of the first energy storage module and the second energy storage module. Exemplarily, the operating condition information of the first power converter and the second power converter can be monitored by a built-in monitoring module, and the operating condition information of the first energy storage module and the second energy storage module can be monitored by a battery management system and can be transmitted to the controller so that the controller can analyze the operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module and perform operating condition anomaly detection.

[0127] S6: When it is determined based on the operating condition information that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the current output power of the first power converter and the current output power of the second power converter are reduced by a fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0128] Specifically, when the controller determines, based on operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, for example, when the operating voltage, operating current, or operating temperature of at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module exceeds a safe range, the controller can issue an alarm message and can reduce the current output power of the first power converter and the current output power of the second power converter by a fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0, so as to promptly stop power transmission in the towing system when a fault occurs in the towing system to prevent the fault from further expanding. After adjusting the current output power of the first power converter and the current output power of the second power converter to 0, the controller can control the first power converter and the second power converter to stop operating, thereby providing a safe maintenance environment for operators, facilitating timely troubleshooting of abnormal operating conditions of the towing system, thereby improving the maintenance efficiency of the towing system and enhancing the reliability and stability of the towing system. The fourth preset power adjustment gradient can be understood as a fixed power increment for a single adjustment when the controller adjusts the current output power of the first power converter and the second power converter. The fourth preset power adjustment gradient and the first preset adjustment gradient can be the same or different, and the present invention is not specifically limited thereto. For example, the fourth preset power adjustment gradient can be 200 kW.

[0129] Optionally, the S6 includes:

[0130] S61: When it is determined based on the operating condition information that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, and the smaller of the current output power of the second power converter is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as the high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as the low-power converter.

[0131] Specifically, when the current output power of the first power converter and the current output power of the second power converter are adjusted to 0 by the controller, the current output power of the first power converter and the current output power of the second power converter are first compared, so that the larger one of the current output power of the first power converter and the current output power of the second power converter can be determined as the first output power, and the smaller one can be determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter can be determined as the high-power converter, and the power converter with the second output power among the first power converter and the second power converter can be determined as the low-power converter, thereby providing a basis for the subsequent adjustment process.

[0132] S62: reducing the first output power with a fourth preset power adjustment gradient until the current output power of the high-power converter reaches the second output power.

[0133] Specifically, after determining the first and second output powers, the controller reduces the first output power by a fourth preset power adjustment gradient, reducing the first output power by one fourth preset power adjustment gradient. For example, the first output power is reduced by 200 kW. The controller then obtains the current output power of the high-power converter. If the current output power of the high-power converter does not reach the second output power, the controller continues to reduce the first output power by the fourth preset power adjustment gradient, reducing the first output power by another fourth preset power adjustment gradient. For example, the first output power is reduced by another 200 kW, until the current output power of the high-power converter reaches the second output power. It is understood that when the difference between the current output power of the high-power converter and the second output power is less than the fourth preset power adjustment gradient, the controller reduces the first output power by the difference between the current output power of the high-power converter and the second output power. By reducing the first output power to the second output power, the difference between the current output powers of the first and second power converters is reduced to zero, thereby preventing further escalation of the towing system fault and improving the safety and stability of the towing system. At the same time, by reducing the first output power with the fourth preset power regulation gradient, failure of the energy storage module corresponding to the high-power power converter due to sudden change in charging and discharging power is avoided.

[0134] S63: reducing the current output power of the first power converter and the current output power of the second power converter at a fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0135] Specifically, after the current output power of the high power converter reaches the second output power, the controller will reduce the current output power of the first power converter and the current output power of the second power converter with a fourth preset power adjustment gradient, so that the current output power of the first power converter is reduced by a fourth preset power adjustment gradient, and the current output power of the second power converter is reduced by a fourth preset power adjustment gradient. The adjustment order of the current output powers of the first power converter and the second power converter can be determined according to actual needs. The present invention does not limit this. For example, the current output power of the first power converter is reduced by 200kW, and the current output power of the second power converter is reduced by 200kW. Afterwards, the controller will obtain the current output power of the first power converter and the current output power of the second power converter. When the current output power of the first power converter and the current output power of the second power converter are both greater than 0, the controller will continue to reduce the current output power of the first power converter and the current output power of the second power converter with a fourth preset power regulation gradient, so that the current output power of the first power converter is reduced again by a fourth preset power regulation gradient, and the current output power of the second power converter is reduced again by a fourth preset power regulation gradient. For example, the current output power of the first power converter is reduced again by 200Kw, and the current output power of the second power converter is reduced again by 200Kw, until the current output power of the first power converter and the current output power of the second power converter are both 0, and the adjustment of the current output power of the first power converter and the current output power of the second power converter is stopped.

[0136] It can be understood that the controller adopts an alternating adjustment method of controlling the current output power of the first power converter to reduce a fourth preset power regulation gradient, and then controlling the current output power of the second power converter to reduce a fourth preset power regulation gradient, thereby ensuring that in the process of adjusting the current output power of the first power converter and the current output power of the second power converter, the difference between the current output powers of the first power converter and the second power converter is always maintained at 0, thereby avoiding the imbalance of charging and discharging power in the towing system and improving the stability and flexibility of the towing system.

[0137] Optional, Figure 5 FIG. 1 is a flow chart of another control method for a towing system provided by the present invention. Figure 5 As shown, the control method of the towing system also includes:

[0138] S7: When the output power of the discharge power converter is greater than the output power of the charge power converter, part of the output power of the discharge power converter is controlled to be converted by the transformer and then provided to the commercial power grid.

[0139] Specifically, when the output power of the discharge power converter is greater than the output power of the charging power converter, the controller will control part of the output power of the discharge power converter to be converted through the transformer and provided to the mains power grid, so as to absorb the excess electric energy output by the discharge power converter through the mains power grid to maintain the power balance of the towing system.

[0140] S8: Obtain the grid power value output by the discharge power converter to the commercial power grid.

[0141] Specifically, when a portion of the output power of the discharge power converter is converted by the transformer and provided to the mains grid, the controller can obtain the grid power value output by the discharge power converter to the mains grid, that is, the power transmitted from the secondary side of the transformer to the mains grid. If the power value output by the discharge power converter to the mains grid is too high, it may exceed the absorption capacity of the mains grid or exceed the maximum allowable reverse power of the mains grid. Therefore, it is necessary to monitor the grid power value in real time through the controller to determine whether the output power of the discharge power converter needs to be adjusted.

[0142] S9: When the grid power value is greater than the preset reverse flow threshold, a power difference between the grid power value and the preset reverse flow threshold is obtained.

[0143] Specifically, after the controller obtains the grid power value in real time, it can compare the grid power value with a preset reverse current threshold. The preset reverse current threshold can be specifically understood as the maximum allowable output power output to the mains grid, determined according to the grid connection agreement of the mains grid or the design of the towing system. When it is determined that the grid power value is greater than the preset reverse current threshold, it means that the power value output by the discharge power converter to the mains grid is too large, which may cause grid voltage instability or exceed the maximum allowable output power of the mains grid. Therefore, the controller will obtain the power difference between the grid power value and the preset reverse current threshold to lay the foundation for subsequently reducing the output power of the discharge power converter.

[0144] S10: reducing the output power of the discharge power converter by the power difference.

[0145] Specifically, after determining the power difference between the grid power value and the preset reverse current threshold, the controller will reduce the output power of the discharge power converter by the power difference, so as to accurately reduce the grid power value output by the discharge power converter to the mains power grid to the preset reverse current threshold, thereby avoiding excessive power output to the mains power grid, complying with the grid-connected agreement of the mains power grid, ensuring the grid-connected operation reliability and power transmission smoothness of the towing system, and improving the stability and safety of the towing system.

[0146] Furthermore, after reducing the output power of the discharge power converter by the power difference, the controller will continue to monitor the grid power value output by the discharge power converter to the mains grid. This allows the controller to dynamically adjust the output power of the discharge power converter in a timely manner if the grid power value exceeds a preset reverse current threshold. This allows the system to detect and prevent excessive power output from the towing system to the mains grid, improving its stability and flexibility.

[0147] Optional, Figure 6 This is a schematic diagram of the structure of a control device for a towing system provided by the present invention. The device can implement the control method for the towing system provided by the embodiment of the present invention. The device can be implemented by software and / or hardware and can generally be integrated into the controller of the towing system. Figure 6 As shown, the device includes: an output power acquisition module 10, a current charge and discharge power difference determination module 20, a first current output power adjustment module 30 and a second current output power adjustment module 40. The specific structure of the device is as follows:

[0148] An output power acquisition module 10 is configured to acquire the output power of the first power converter and the output power of the second power converter in real time when the first power converter and the second power converter are charging and discharging;

[0149] a current charge-discharge power difference determining module 20, configured to determine a current charge-discharge power difference based on a current output power of the first power converter and a current output power of the second power converter;

[0150] A first current output power adjustment module 30 is configured to adjust the current output power of the first power converter and the current output power of the second power converter to initial power when the current charge and discharge power difference is within a preset difference range;

[0151] The second current output power adjustment module 40 is configured to adjust the current output power of the first power converter and the current output power of the second power converter to 0 when the current charge-discharge power difference is greater than an upper limit of a preset difference range.

[0152] In an optional embodiment of the present invention, the output power acquisition module 10 can also be used to: when starting the first power converter and the second power converter for charging and discharging, adjust the initial output power of the first power converter to the initial power, and adjust the initial output power of the second power converter to the initial power.

[0153] In an optional embodiment of the present invention, the output power acquisition module 10 can also be used to: when starting the first power converter and the second power converter for charging and discharging, increase the current initial output power of the first power converter and the current initial output power of the second power converter with a first preset power adjustment gradient until the current initial output power of the first power converter and the current initial output power of the second power converter are both initial powers.

[0154] In an optional embodiment of the present invention, the first current output power adjustment module 30 can also be used to: when the current charge and discharge power difference is within a preset difference range, adjust the current output power of the first power converter and the current output power of the second power converter respectively with a second power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both the initial power.

[0155] In an optional embodiment of the present invention, the first current output power adjustment module 30 can also be used to: when the current charge and discharge power difference is within a preset difference range, determine the larger one of the current output power of the first power converter and the current output power of the second power converter as the first output power, and the smaller one as the second output power, and determine the power converter with the first output power among the first power converter and the second power converter as the high-power converter, and determine the power converter with the second output power among the first power converter and the second power converter as the low-power converter; reduce the first output power until the power difference between the current output power of the high-power converter and the second output power reaches the lower limit of the preset difference range; adjust the first output power and the second output power respectively with the second preset power adjustment gradient until the current output power of the high-power converter and the current output power of the low-power converter are both the initial power.

[0156] In an optional embodiment of the present invention, the second current output power adjustment module 40 can also be used to: when the current charge and discharge power difference is greater than the upper limit value of the preset difference range, reduce the current output power of the first power converter and the current output power of the second power converter with a third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0157] In an optional embodiment of the present invention, the second current output power adjustment module 40 can also be used to: when the current charge and discharge power difference is greater than the upper limit value of the preset difference range, determine the larger one of the current output power of the first power converter and the current output power of the second power converter as the first output power, and the smaller one as the second output power, and determine the power converter with the first output power among the first power converter and the second power converter as the high-power converter, and determine the power converter with the second output power among the first power converter and the second power converter as the low-power converter; reduce the first output power with a third preset power adjustment gradient; reduce the second output power with a third preset power adjustment gradient; when the current output power of the low-power converter is greater than 0, return to execute the steps of reducing the first output power with the third preset power adjustment gradient to reducing the second output power with the third preset power adjustment gradient until the current output power of the low-power converter is 0; when the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, return to execute the steps of reducing the second output power with the third preset power adjustment gradient until the current output power of the high-power converter is 0.

[0158] In an optional embodiment of the present invention, the second current output power adjustment module 40 can also be used to: obtain in real time the operating condition information of the first power converter, the second power converter, the first energy storage module and the second energy storage module; the operating condition information includes the operating voltage, the operating current and the operating temperature; when it is determined based on the operating condition information that at least one of the first power converter, the second power converter, the first energy storage module and the second energy storage module is abnormal, reduce the current output power of the first power converter and the current output power of the second power converter with a fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0159] In an optional embodiment of the present invention, the second current output power adjustment module 40 can also be used for: when it is determined that at least one of the first power converter, the second power converter, the first energy storage module and the second energy storage module is abnormal based on the operating condition information, the larger one of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, and the smaller one is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as the high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as the low-power converter; reducing the first output power with a fourth preset power adjustment gradient until the current output power of the high-power converter reaches the second output power; reducing the current output power of the first power converter and the current output power of the second power converter with the fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0160] In an optional embodiment of the present invention, the second current output power adjustment module 40 can also be used to: when the output power of the discharge power converter is greater than the output power of the charging power converter, control part of the output power of the discharge power converter to be converted through the transformer and provided to the mains power grid; obtain the grid power value output by the discharge power converter to the mains power grid; when the grid power value is greater than a preset reverse current threshold, obtain the power difference between the grid power value and the preset reverse current threshold; and reduce the output power of the discharge power converter by the power difference.

[0161] The control device for the towing system described above can execute the control method for the towing system provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method. For technical details not fully described in this embodiment, please refer to the control method for the towing system provided in any embodiment of the present invention.

[0162] Since the control device for the towing system described above is a device that can execute the control method for the towing system in the embodiment of the present invention, based on the control method for the towing system described in the embodiment of the present invention, those skilled in the art can understand the specific implementation method and various variations of the control device for the towing system in this embodiment. Therefore, how the control device for the towing system implements the control method for the towing system in the embodiment of the present invention will not be described in detail here. As long as those skilled in the art can implement the device used by the control method for the towing system in the embodiment of the present invention, it falls within the scope of protection of this application.

[0163] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present invention can be achieved. This is not limited herein.

[0164] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A control method for a towing system, characterized in that: The towing system includes a first power converter and a second power converter connected in series; and a control method of the towing system includes: S1: acquiring, in real time, the output power of the first power converter and the output power of the second power converter when the first power converter and the second power converter are charging and discharging; S2: determining a current charge-discharge power difference according to a current output power of the first power converter and a current output power of the second power converter; S3: When the current charge-discharge power difference is within a preset difference range, adjusting the current output power of the first power converter and the current output power of the second power converter to initial power; S4: When the current charge-discharge power difference is greater than an upper limit of the preset difference range, adjusting the current output power of the first power converter and the current output power of the second power converter to 0.

2. The control method of the towing system according to claim 1, characterized in that: Before the S1, it also includes: S0: When starting the first power converter and the second power converter for charging and discharging, adjusting the initial output power of the first power converter to the initial power, and adjusting the initial output power of the second power converter to the initial power.

3. The control method of the towing system according to claim 2, characterized in that: The S0 includes: S01: When starting the first power converter and the second power converter for charging and discharging, the current initial output power of the first power converter and the current initial output power of the second power converter are increased with a first preset power adjustment gradient until the current initial output power of the first power converter and the current initial output power of the second power converter are both the initial power.

4. The control method of the towing system according to claim 1, characterized in that: The S3 includes: S31: When the current charge and discharge power difference is within the preset difference range, the current output power of the first power converter and the current output power of the second power converter are respectively adjusted with a second preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both the initial power.

5. The control method of the towing system according to claim 4, characterized in that: The S31 includes: S311: When the current charge-discharge power difference is within the preset difference range, determine the larger of the current output power of the first power converter and the current output power of the second power converter as the first output power, and the smaller of the current output power as the second output power, and determine the power converter having the first output power of the first power converter and the second power converter as the high-power converter, and determine the power converter having the second output power of the first power converter and the second power converter as the low-power converter; S312: reducing the first output power until the power difference between the current output power of the high-power converter and the second output power reaches a lower limit of the preset difference range; S313: Regulating the first output power and the second output power respectively with the second preset power regulation gradient until the current output power of the high-power converter and the current output power of the low-power converter are both the initial power.

6. The control method of the towing system according to claim 1, characterized in that: The S4 includes: S41: When the current charge and discharge power difference is greater than the upper limit value of the preset difference range, the current output power of the first power converter and the current output power of the second power converter are reduced with a third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

7. The control method of the towing system according to claim 6, characterized in that: The S41 includes: S411: When the current charge-discharge power difference is greater than an upper limit of the preset difference range, determining the larger of the current output power of the first power converter and the current output power of the second power converter as a first output power, and the smaller of the current output power of the first power converter and the second power converter as a second output power, and determining the power converter having the first output power of the first power converter and the second power converter as a high-power converter, and determining the power converter having the second output power of the first power converter and the second power converter as a low-power converter; S412: reducing the first output power by the third preset power adjustment gradient; S413: reducing the second output power by the third preset power adjustment gradient; S414: When the current output power of the low-power converter is greater than 0, return to executing S412 to S413 until the current output power of the low-power converter is 0; S415: When the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, return to execute S413 until the current output power of the high-power converter is 0.

8. The control method of the towing system according to claim 1, characterized in that: The towing system further includes a first energy storage module and a second energy storage module; the first power converter is connected to the first energy storage module; the second power converter is connected to the second energy storage module; and the control method of the towing system further includes: S5: Acquire operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module in real time; the operating condition information includes operating voltage, operating current, and operating temperature; S6: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, reducing the current output power of the first power converter and the current output power of the second power converter by a fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

9. The control method of the towing system according to claim 8, characterized in that: The S6 includes: S61: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, determining the larger of the current output power of the first power converter and the current output power of the second power converter as a first output power, and the smaller of the current output power of the first power converter and the second power converter as a second output power, and determining the power converter having the first output power among the first power converter and the second power converter as a high-power converter, and determining the power converter having the second output power among the first power converter and the second power converter as a low-power converter; S62: reducing the first output power at the fourth preset power adjustment gradient until the current output power of the high-power converter reaches the second output power; S63: Reduce the current output power of the first power converter and the current output power of the second power converter by the fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

10. The control method of the towing system according to claim 1, characterized in that: The towing system further includes a transformer; the AC end of the first power converter and the AC end of the second power converter are both electrically connected to the primary side of the transformer, and the secondary side of the transformer is electrically connected to the mains power grid; one of the first power converter and the second power converter is a charging power converter, and the other is a discharging power converter; the control method of the towing system further includes: S7: When the output power of the discharge power converter is greater than the output power of the charge power converter, controlling part of the output power of the discharge power converter to be converted by the transformer and then provided to the commercial power grid; S8: Obtaining a grid power value outputted from the discharge power converter to the commercial power grid; S9: When the grid power value is greater than a preset reverse flow threshold, obtaining a power difference between the grid power value and the preset reverse flow threshold; S10: reducing the output power of the discharge power converter by the power difference.

11. A control device for a towing system, characterized in that: The towing system includes a first power converter and a second power converter connected in series; and the control device of the towing system includes: an output power acquisition module, configured to acquire the output power of the first power converter and the output power of the second power converter in real time when the first power converter and the second power converter are charging and discharging; a current charge-discharge power difference determining module, configured to determine a current charge-discharge power difference according to a current output power of the first power converter and a current output power of the second power converter; a first current output power adjustment module, configured to adjust the current output power of the first power converter and the current output power of the second power converter to initial power when the current charge-discharge power difference is within a preset difference range; The second current output power adjustment module is configured to adjust the current output power of the first power converter and the current output power of the second power converter to 0 when the current charge-discharge power difference is greater than an upper limit of the preset difference range.

12. A towing system, characterized in that: include: a controller, and a first power converter and a second power converter connected in series; The controller is connected to the first power converter and the second power converter respectively, and the controller is used to execute the control method of the towing system according to any one of claims 1 to 10.

13. The towing system according to claim 12, characterized in that: The towing system further includes a transformer; The AC end of the first power converter and the AC end of the second power converter are both electrically connected to the primary side of the transformer, and the secondary side of the transformer is electrically connected to the mains power grid; One of the first power converter and the second power converter is a charging power converter, and the other is a discharging power converter.

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