Direct current busbar voltage automatic tracking control method, circuit, system and storage medium

Abstract

The invention relates to a direct-current busbar voltage automatic tracking control method, circuit and system and a storage medium, the system comprises a direct-current converter, a transmission cable and a far-end direct-current busbar device, the input end of the direct-current converter is connected with a power supply, and the output end of the direct-current converter is connected with a direct-current busbar in a power system through the transmission cable; the method comprises the following steps: controlling a direct-current converter to issue test current to a direct-current busbar for multiple times through a transmission cable, and reading current and voltage in the transmission cable after a preset duration to obtain multiple sampling currents and multiple sampling voltages; calculating the line impedance of the transmission cable according to the plurality of sampling currents and the plurality of sampling voltages; and calculating a reference voltage of a voltage loop according to the line impedance, and taking the reference voltage as a tracking voltage of the DC busbar. The line impedance is calculated by issuing the test voltage to the DC busbar for multiple times, and the tracking voltage is obtained according to the line impedance, so that the influence of the line impedance is solved, and the busbar voltage automatic tracking function is realized.

Description

Technical Field

[0001] The present application relates to the field of power supply control technology, and in particular to a method, circuit, system and storage medium for automatic tracking control of a DC bus voltage. Background Art

[0002] For the existing DC power supply system, when the DC busbar is connected to multiple energy outputs at the same time, the currently connected switching power supply is set to low priority, and the subsequent connection to the long-distance power supply energy is set to high priority. In order to give priority to the output of high-priority energy, the output voltage of other energy sources needs to be set higher than the original switching power supply. Because the long-distance power supply energy requires a longer cable, the line will be damaged after the energy output voltage reaches the DC busbar. At present, the output voltage of other energy sources is calculated and debugged manually based on the output voltage of the switching power supply.

[0003] However, the current calculation method has certain drawbacks: first, it cannot be set automatically and needs to be manually debugged on site, which increases the workload of manual commissioning; second, if the voltage is set inappropriately, high-priority energy cannot be fully utilized, or the busbar voltage changes and cannot automatically follow, increasing the risk of wasting high-priority energy. Summary of the invention

[0004] The embodiments of the present application provide a method, circuit, system and storage medium for automatic tracking and control of a DC bus voltage, so as to at least solve the problem in the related art that the bus sampling voltage needs to be manually calculated and set.

[0005] In a first aspect, an embodiment of the present application provides a method for automatically tracking and controlling a DC busbar voltage, the method being applied to a DC power supply system to which multiple new energy sources are connected, the system comprising a DC converter, a transmission cable, and a remote DC busbar device, the input end of the DC converter being connected to the new energy source, and the output end being connected to a DC busbar in the remote DC busbar device through the transmission cable;

[0006] The method comprises:

[0007] Sending test current to the DC busbar multiple times through the DC converter and the transmission cable, and reading the current and voltage in the transmission cable after a preset time to obtain multiple sampled currents and multiple sampled voltages;

[0008] Calculating the line impedance of the transmission cable according to the plurality of sampled currents and the plurality of sampled voltages;

[0009] A reference voltage of a voltage loop is calculated according to the line impedance, and the reference voltage is used as a tracking voltage of the DC busbar.

[0010] In one embodiment, the test current is sent to the DC busbar multiple times through the DC converter and the transmission cable, and the current and voltage in the transmission cable are read after a preset time to obtain multiple sampled currents and multiple sampled voltages, including:

[0011] Controlling the DC converter to send a first test current to the DC busbar through the transmission cable, and reading a first sampled current and a first sampled voltage in the transmission cable after a first preset time;

[0012] After a preset time interval, the DC converter is controlled to send a second test current to the DC busbar through the transmission cable, and after a second preset time length, a second sampled current and a second sampled voltage in the transmission cable are read.

[0013] In one embodiment, calculating the line impedance of the transmission cable according to a plurality of sampled currents and a plurality of sampled voltages includes:

[0014] Calculating a difference between the first sampling current and the second sampling current to obtain a current difference;

[0015] Calculating a difference between the first sampling voltage and the second sampling voltage to obtain a voltage difference;

[0016] The line impedance is obtained by calculating according to the current difference and the voltage difference.

[0017] In one embodiment, the calculating the line impedance of the transmission cable according to the multiple sampled currents and the multiple sampled voltages further includes:

[0018] Performing pairwise calculations on the multiple sampled currents and sampled voltages to obtain multiple line impedances;

[0019] After comparing the magnitudes of multiple line impedances, the line impedances with the largest and smallest values ​​are eliminated to obtain a line impedance set;

[0020] An average value is calculated for all line impedances in the line impedance set to obtain a final line impedance value.

[0021] In one embodiment, the calculation formula of the reference voltage is:

[0022] Vref=Vbus+Rline*Iout

[0023] Wherein, Vref is a reference voltage, Vbus is a voltage across a DC busbar, Rline is a line impedance of a transmission line, and Iout is an output current of a DC converter.

[0024] In a second aspect, an embodiment of the present application provides a DC busbar voltage automatic tracking circuit, including a DC converter and a transmission cable.

[0025] The input end of the DC converter is connected to the new energy source, and the output end is connected to the DC busbar in the remote DC busbar device through the transmission cable; wherein,

[0026] The DC converter is used to convert the fixed DC power or fixed AC power output by the new energy source into variable DC power that meets user needs;

[0027] The transmission cable is used to transmit the variable direct current to the direct current busbar;

[0028] The DC converter is used to send test current to the DC busbar multiple times, and after a preset time, read the current and voltage in the transmission cable to obtain multiple sampled currents and multiple sampled voltages; calculate the line impedance of the transmission cable according to the multiple sampled currents and multiple sampled voltages; and calculate the reference voltage of the voltage loop according to the line impedance.

[0029] In one embodiment, the DC converter includes a voltage control loop and a current control loop, wherein:

[0030] The voltage control loop is used to control the DC converter to output a stable voltage according to the reference voltage;

[0031] A reference current is obtained, and a current control loop is used to control the DC converter to output a stable current according to the reference current.

[0032] The current control loop is used to ensure that the DC converter outputs a preset sampling current. In one embodiment, the DC converter is a DCDC converter or an ACDC converter.

[0033] In a third aspect, an embodiment of the present application provides a DC power supply system, the system comprising a power supply, a remote DC bus device and a busbar voltage automatic tracking circuit as described in any of the above embodiments, wherein the busbar voltage automatic tracking circuit is connected between the power supply and the DC bus, and the power supply comprises a variety of new energy sources.

[0034] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the busbar voltage automatic tracking and control method as described in the first aspect above.

[0035] The busbar voltage automatic tracking control method, circuit, system and storage medium provided by the embodiments of the present application have at least the following technical effects:

[0036] A test current is sent to the DC busbar multiple times through a transmission cable, and the current and voltage in the transmission cable are read after a preset time to obtain multiple sampled currents and multiple sampled voltages; the line impedance of the transmission cable is calculated based on the multiple sampled currents and multiple sampled voltages; the reference voltage of the voltage loop is calculated based on the line impedance, thereby realizing a constant current function, solving the influence of the line impedance, and realizing an automatic busbar voltage tracking function; and through the control method of the present application, a reference voltage can be obtained without manual intervention, solving the problem that the output voltage needs to be manually calculated and set.

[0037] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0039] Figure 1 This is a structural block diagram of a busbar voltage automatic tracking circuit in one embodiment of the present application;

[0040] Figure 2 It is a flow chart of a busbar voltage automatic tracking control method in one embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0042] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0043] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0044] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0045] In the current long-transmission power system, when the DC converter is connected to the remote bus through a long transmission line, there is a voltage difference between the port voltage sampled by the DC converter and the bus voltage due to the line impedance, resulting in the line current failing to reach the target current, thereby causing the DC converter to fail to reach the expected set output current and the controller to lose control.

[0046] Based on the above situation, the present application proposes a DC bus voltage automatic tracking control method, circuit, system and storage medium to solve the problems of voltage drop compensation and priority use in long-distance wiring of new energy sources, while solving the problem that the output voltage needs to be manually calculated and set, and reducing costs.

[0047] In one embodiment, the present application provides a DC busbar voltage automatic tracking circuit, which is applied to a DC power supply system connected to a variety of new energy sources, and specifically refers to Figure 1 , including a DC converter and a transmission cable, wherein the input end of the DC converter is connected to a new energy source, and the output end is connected to a DC busbar in a remote DC busbar device through the transmission cable, and the DC converter includes a PI control loop. In the present application, the DC converter is a DCDC converter or an ACDC converter.

[0048] In this embodiment, the DC converter is used to convert the fixed DC power or fixed AC power output by the new energy into variable DC power that meets user needs; the transmission cable is used to transmit the variable DC power to the DC bus; the DC converter collects the voltage and current in the transmission cable; the DC converter is used to send test current to the DC bus multiple times, and after a preset time, read the current and voltage in the transmission cable to obtain multiple sampled currents and multiple sampled voltages; calculate the line impedance of the transmission cable according to the multiple sampled currents and multiple sampled voltages; calculate the reference voltage of the voltage loop according to the line impedance, and use the reference voltage as the tracking voltage of the DC bus.

[0049] More specifically, the DC converter includes a voltage control loop and a current control loop, and the voltage control loop and the current control loop are connected to the transmission cable. The voltage control loop is used to control the DC converter to output a stable voltage according to the reference voltage; obtain a reference current, and the current control loop is used to control the DC converter to output a stable current according to the reference current.

[0050] In the second aspect, the embodiment of the present application provides a method for automatically tracking and controlling a DC bus voltage, which is applied to a DC power supply system with multiple new energy sources connected, the system includes a DC converter, a transmission cable, and a remote DC bus device, the input end of the DC converter is connected to the new energy source, and the output end is connected to the DC bus in the remote DC bus device through the transmission cable, and the DC converter includes a PI control loop. The present application achieves the output of multiple energy sources according to priority through a bus voltage automatic tracking circuit and control method. Specifically, the method is implemented by the following steps.

[0051] Step S1, controlling the DC converter to send a test current to the DC busbar through the transmission cable for multiple times, and reading the current and voltage in the transmission cable after a preset time to obtain multiple sampled currents and multiple sampled voltages;

[0052] Specifically, the DC converter is controlled to send a first test current to the DC busbar through the transmission cable for multiple times, and a first sampled current and a first sampled voltage in the transmission cable are read after a first preset time period; after a preset time interval (this time interval can be determined by the user, and the default setting in this application is 3 seconds), the DC converter is controlled to send a second test current to the DC busbar through the transmission cable, and a second sampled current and a second sampled voltage in the transmission cable are read after a second preset time period, and so on, to obtain multiple groups of sampled voltages and sampled currents.

[0053] Step S2, calculating the line impedance of the transmission cable according to multiple sampled currents and multiple sampled voltages; specifically, calculating the line impedance of the transmission cable according to multiple sampled currents and multiple sampled voltages, including: calculating the difference between the first sampled current and the second sampled current to obtain the current difference; calculating the difference between the first sampled voltage and the second sampled voltage to obtain the voltage difference; calculating according to the current difference and the voltage difference to obtain the line impedance.

[0054] In a preferred embodiment, the multiple sampled currents and sampled voltages are calculated in pairs to obtain multiple line impedances; after comparing the multiple line impedances, the line impedances with the largest and smallest values ​​are eliminated to obtain a line impedance set; and the average value of all line impedances in the line impedance set is calculated to obtain a final line impedance value.

[0055] Step S3, calculating a reference voltage of the voltage loop according to the line impedance, and using the reference voltage as the tracking voltage of the DC busbar. Specifically, the calculation formula of the reference voltage is:

[0056] Vref=Vbus+Rline*Iout

[0057] Wherein, Vref is the reference voltage including the cable voltage drop, Vbus is the voltage across the DC busbar, Rline is the line impedance of the transmission line, and Iout is the output current of the DC converter.

[0058] In a specific embodiment, after the DC-DC is started, the test current Iref1 is automatically sent after a delay of 3 seconds, and the sampled currents Iout1 and Vout1 are read after waiting for 3 seconds; after a certain period of time, the test current Iref2 is sent again, and the sampled currents Iout2 and Vout2 are read after waiting for 3 seconds. Then, the line impedance is calculated based on the two sampling results, and the calculation formula is shown in formula (1):

[0059] Rline= Vout1-Vout2 (1)

[0060] Iout1-Iout2

[0061] Repeat the above steps to obtain a set of line impedance values, then compare the values, delete the maximum and minimum values, and then add up the remaining values ​​to get the average value as the line impedance calculation result. After obtaining the line impedance value, recalculate the reference voltage based on the value as the reference value of the control voltage loop. The calculation process refers to formula (2):

[0062] Vref=Vbus+Rline*Iout (2)

[0063] The output voltage of the DC / DC unit is superimposed with the voltage required by the line impedance on the preset voltage to ensure that it is higher than the remote bus voltage, and can work in a constant current discharge state to achieve a constant current function. The automatic tracking of this application is to ensure that the voltage output by the DC / DC is always higher than the remote bus voltage by repeatedly performing the above process to achieve the purpose of tracking. After the above processing, the constant current charge and discharge can realize the constant current function, solve the influence of the line impedance, and realize the automatic tracking function of the bus voltage.

[0064] The above implementation scheme is not limited to the DC-DC converter topology type, and the AC-DC converter topology can also be implemented. The calculated line impedance is very close to the actual impedance, which verifies the effectiveness of the algorithm. It works well in DCDC products, solves the voltage difference problem caused by long lines, and achieves the purpose of automatically tracking the remote busbar voltage.

[0065] In summary, the tracking circuit provided in the embodiment of the present application sends the test current to the DC busbar multiple times through the transmission cable, and reads the current and voltage in the transmission cable after a preset time to obtain multiple sampled currents and multiple sampled voltages; calculates the line impedance of the transmission cable according to the multiple sampled currents and multiple sampled voltages; calculates the reference voltage of the voltage loop according to the line impedance, and uses the reference voltage as the tracking voltage of the DC busbar, so that the constant current function can be realized, the influence of the line impedance is solved, and the busbar voltage automatic tracking function is realized; and through the control method of the present application, the reference voltage can be obtained without manual intervention, which solves the problem that the output voltage needs to be manually calculated and set. In addition, the tracking circuit provided by the present application has simple logic, is easy to implement, saves labor costs, simplifies manual operation, and can be adaptively adjusted.

[0066] In a third aspect, an embodiment of the present application provides a DC power supply system, characterized in that the system includes a power supply, a DC bus and a DC bus voltage automatic tracking circuit as described in any of the above embodiments, wherein the DC bus voltage automatic tracking circuit is connected between the power supply and the DC bus.

[0067] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a program stored thereon, and when the program is executed by a processor, the DC bus voltage automatic tracking control method provided in the first aspect is implemented.

[0068] The readable storage medium may include but is not limited to: a portable disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, an optical storage device, a magnetic storage device or any suitable combination of the above.

[0069] In a possible implementation, the present invention can also be implemented in the form of a program product, which includes a program code. When the program product is run on a terminal device, the program code is used to enable the terminal device to execute the steps of the DC bus voltage automatic tracking control method provided in the first aspect.

[0070] The program code for executing the present invention may be written in any combination of one or more programming languages, and may be executed entirely on a user device, partially on a user device, as an independent software package, partially on a user device and partially on a remote device, or entirely on a remote device.

[0071] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A DC busbar voltage automatic tracking control method, characterized in that: The method is applied to a DC power supply system connected to multiple new energy sources, the system comprising a DC converter, a transmission cable and a remote DC busbar device, the input end of the DC converter is connected to the new energy source, and the output end is connected to the DC busbar in the remote DC busbar device through the transmission cable; The method comprises: Sending test current to the DC busbar multiple times through the DC converter and the transmission cable, and reading the current and voltage in the transmission cable after a preset time to obtain multiple sampled currents and multiple sampled voltages; Calculating the line impedance of the transmission cable according to the plurality of sampled currents and the plurality of sampled voltages; A reference voltage of a voltage loop is calculated according to the line impedance, and the reference voltage is used as a tracking voltage of the DC busbar.

2. The control method according to claim 1, characterized in that: The method includes sending a test current to the DC busbar multiple times through a DC converter and a transmission cable, and reading the current and voltage in the transmission cable after a preset time to obtain multiple sampled currents and multiple sampled voltages, including: Controlling the DC converter to send a first test current to the DC busbar through the transmission cable, and reading a first sampled current and a first sampled voltage in the transmission cable after a first preset time; After a preset time interval, the DC converter is controlled to send a second test current to the DC busbar through the transmission cable, and after a second preset time length, a second sampled current and a second sampled voltage in the transmission cable are read.

3. The control method according to claim 2, characterized in that: Calculating the line impedance of the transmission cable according to the plurality of sampled currents and the plurality of sampled voltages includes: Calculating a difference between the first sampling current and the second sampling current to obtain a current difference; Calculating a difference between the first sampling voltage and the second sampling voltage to obtain a voltage difference; The line impedance is obtained by calculating according to the current difference and the voltage difference.

4. The control method according to claim 1, characterized in that: The calculating the line impedance of the transmission cable according to the plurality of sampled currents and the plurality of sampled voltages further comprises: Performing pairwise calculations on the multiple sampled currents and sampled voltages to obtain multiple line impedances; After comparing the magnitudes of multiple line impedances, the line impedances with the largest and smallest values ​​are eliminated to obtain a line impedance set; An average value is calculated for all line impedances in the line impedance set to obtain a final line impedance value.

5. The control method according to claim 1, characterized in that: The calculation formula of the reference voltage is: Vref=Vbus+Rline*Iout Among them, Vref is the reference voltage, Vbus is the voltage across the DC bus, Rline is the line impedance of the transmission line, and Iout is the output current of the DC converter.

6. A DC busbar voltage automatic tracking circuit, characterized in that: Including DC converter and transmission cable, The input end of the DC converter is connected to the new energy source, and the output end is connected to the DC busbar in the remote DC busbar device through the transmission cable; wherein, The DC converter is used to convert the fixed DC power or fixed AC power output by the new energy source into variable DC power that meets user needs; The transmission cable is used to transmit the variable direct current to the direct current busbar; The DC converter is used to send test current to the DC busbar multiple times, and after a preset time, read the current and voltage in the transmission cable to obtain multiple sampled currents and multiple sampled voltages; calculate the line impedance of the transmission cable according to the multiple sampled currents and multiple sampled voltages; and calculate the reference voltage of the voltage loop according to the line impedance.

7. The busbar voltage automatic tracking circuit according to claim 6, characterized in that: The DC converter includes a voltage control loop and a current control loop, wherein: The voltage control loop is used to control the DC converter to output a stable voltage according to the reference voltage; A reference current is obtained, and a current control loop is used to control the DC converter to output a stable current according to the reference current.

8. The busbar voltage automatic tracking circuit according to claim 6, characterized in that: The DC converter is a DCDC converter or an ACDC converter.

9. A DC power supply system, characterized in that: The system includes a power supply, a remote DC bus device and a bus voltage automatic tracking circuit according to any one of claims 6 to 8, wherein the bus voltage automatic tracking circuit is connected between the power supply and the DC bus, and the power supply includes a variety of new energy sources.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the busbar voltage automatic tracking control method according to any one of claims 1 to 5 is implemented.

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