A communication-free based low-voltage line end flexible interconnection control method and device

Abstract

The application discloses a kind of low-voltage line end flexible interconnection control method and device based on non-communication in the field of power electronic control technology, comprising: obtaining low-voltage line end AC side voltage and current DC side voltage;Determine whether low-voltage line end AC side voltage is in voltage qualified interval;In response to AC side voltage not in voltage qualified interval, determine the deviation value of AC side voltage deviating from voltage qualified interval, otherwise do not handle;Combine current DC side voltage and the deviation value of AC side voltage deviating from voltage qualified interval, determine DC side voltage instruction;DC voltage instruction is input into voltage control loop, and DC voltage is adjusted by converter.The application can ensure that low-voltage line end flexible interconnection system can realize voltage balance and realize power automatic regulation under non-communication condition.

Description

Technical Field

[0001] This invention relates to a control method and device for flexible interconnection at the end of a low-voltage line without communication, belonging to the field of power electronics control technology. Background Technology

[0002] With the large-scale integration of distributed power sources into low-voltage lines, voltage quality problems in low-voltage distribution networks have become frequent. To address this, interconnecting low-voltage lines at their ends using flexible DC transmission devices can effectively solve problems such as insufficient line capacity, excessively high or low voltage, break the constraints of radial operation of low-voltage lines, achieve dynamic capacity expansion of lines, balance the load rate of interconnected lines, and ensure safe and reliable power supply to critical loads.

[0003] Multi-terminal interconnected systems typically employ a master-slave control approach. One AC / DC converter is responsible for stabilizing the DC voltage Udc, while other AC / DC converters operate in PQ mode (current source). This means that the system includes one master voltage source and multiple controllable current sources, relying on system-level coordinated control for dynamic power allocation. This approach places high demands on communication, specifically manifested in the following ways:

[0004] 1) When the communication line ages or is accidentally disconnected, the system cannot dynamically allocate power, resulting in a shutdown due to a fault.

[0005] 2) In application scenarios where the distance between low-voltage lines is long and the site environment is complex, making it inconvenient to lay communication lines, the multi-terminal interconnection system cannot work properly. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a control method and device for flexible interconnection at the end of a low-voltage line without communication, which can ensure that the flexible interconnection system at the end of the low-voltage line can achieve voltage balance and automatic power adjustment in the absence of communication.

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0008] In a first aspect, the present invention provides a control method for flexible interconnection at the end of a low-voltage line based on communication-free communication, comprising:

[0009] Obtain the AC side voltage at the end of the low-voltage line and the current DC side voltage;

[0010] Determine whether the AC voltage at the end of the low-voltage line is within the acceptable voltage range;

[0011] When the AC side voltage is outside the acceptable voltage range, determine the deviation value of the AC side voltage from the acceptable voltage range; otherwise, no action is taken.

[0012] The DC side voltage command is determined by combining the deviations of the current DC side voltage and AC side voltage from the qualified voltage range;

[0013] The DC-side voltage command is input into the voltage control loop, and the DC voltage is adjusted through the converter.

[0014] Furthermore, the AC side voltage at the end of the low-voltage line is obtained through the AC side voltage transformer of the converter.

[0015] Furthermore, the qualified voltage range includes the qualified voltage range at the receiving end of a single-phase 220V residential customer and the qualified voltage range at the client end of a three-phase 380V customer. Specifically, the qualified voltage range at the receiving end of a single-phase 220V residential customer is: the highest voltage during power consumption is not higher than 236V and the lowest voltage is not lower than 198V; the qualified voltage range at the client end of a three-phase 380V customer is: the highest voltage during power consumption is not higher than 407V and the lowest voltage is not lower than 353V.

[0016] Furthermore, the statement that the AC side voltage is not within the qualified voltage range includes two cases: AC side voltage > the upper limit of the qualified voltage or AC side voltage < the lower limit of the qualified voltage.

[0017] Furthermore, the formula for calculating the deviation of the AC side voltage from the acceptable voltage range is as follows:

[0018] (1)

[0019] in, AC side voltage, and These are the upper and lower limits of the acceptable voltage range, respectively. This represents the deviation of the AC side voltage from the acceptable voltage range.

[0020] Furthermore, the calculation formula for the DC-side voltage command is as follows:

[0021] (2)

[0022] in, This is a DC-side voltage command. This is the current DC-side voltage. These are the modulation parameters.

[0023] Secondly, the present invention provides a control device for flexible interconnection at the end of a low-voltage line without communication, comprising:

[0024] Voltage acquisition module: used to acquire the AC side voltage at the end of the low-voltage line and the current DC side voltage;

[0025] Judgment module: Used to determine whether the AC side voltage at the end of the low-voltage line is within the acceptable voltage range;

[0026] Deviation value determination module: used to determine the deviation value of AC side voltage from the qualified voltage range when the AC side voltage is not within the qualified voltage range; otherwise, no action is taken.

[0027] Command determination module: used to determine the DC side voltage command by combining the deviation values ​​of the current DC side voltage and AC side voltage from the qualified voltage range;

[0028] Voltage regulation module: Used to input DC side voltage commands into the voltage control loop, and adjust the DC voltage through the converter.

[0029] Thirdly, the present invention provides a control device for flexible interconnection at the end of a low-voltage line without communication, including a processor and a storage medium;

[0030] The storage medium is used to store instructions;

[0031] The processor is configured to operate according to the instructions to perform the steps of the method according to any of the foregoing.

[0032] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0033] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0034] This invention provides a control method, device, and storage medium for flexible interconnection at the end of low-voltage lines without communication. It can ensure that the flexible interconnection system at the end of low-voltage lines can achieve voltage balance and automatic power adjustment even without communication. The power control of the flexible interconnection at the end of low-voltage lines does not depend on communication, which solves the problem of difficult wiring or communication failure in complex application scenarios. At the same time, by reasonably setting the modulation parameters, robust control can be achieved under the condition of new energy fluctuations. Attached Figure Description

[0035] Figure 1 This is a flowchart of a flexible interconnection control method for low-voltage line terminals based on communication-free operation, provided in Embodiment 1 of the present invention. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0037] Example 1:

[0038] This embodiment discloses a control method for flexible interconnection at the end of a low-voltage line based on communication-free communication, including:

[0039] The AC side voltage at the end of the low-voltage line is obtained, which can be obtained by the AC side voltage transformer PT of the converter.

[0040] Determine whether the AC voltage at the end of the line is within the acceptable voltage range; if the AC voltage is greater than the upper limit of the acceptable voltage, the DC voltage needs to be increased; if the AC voltage is less than the lower limit of the acceptable voltage, the DC voltage needs to be decreased; if it is within the acceptable range, the DC voltage does not need to be changed; calculate the AC voltage deviation value based on this.

[0041] Obtain the current DC-side voltage and DC voltage adjustment value, and determine the DC-side voltage command;

[0042] The actual DC voltage command is input into the voltage control loop, and the DC voltage is adjusted through the converter.

[0043] The acceptable voltage range for the AC side of the low-voltage line includes:

[0044] For single-phase 220V residential customers, the acceptable voltage range at the receiving end is -10% to +7%, meaning that the highest voltage during power use should not exceed 236V and the lowest voltage should not be lower than 198V.

[0045] The acceptable voltage range for a three-phase 380V power supply client is -7% to +7%, meaning the highest voltage during power use should not exceed 407V and the lowest voltage should not be lower than 353V. The AC side voltage at the end of the line is compared with this acceptable range to determine if the AC side voltage meets the requirements.

[0046] (3)

[0047] in, AC side voltage, and These are the upper and lower limits for acceptable AC voltage, respectively. This refers to the deviation of the AC side voltage from the acceptable voltage range; if A positive value indicates that the voltage is too high; if A negative value indicates that the voltage is too low; if... A value of 0 indicates that the value is within the acceptable range.

[0048] DC-side voltage command adjustment methods include:

[0049] (4)

[0050] in, This is a DC-side voltage command. This is the current DC-side voltage. This is a modulation parameter, which needs to be modulated based on parameters such as the load factor and resistance of the low-voltage line, and the resistance of the DC line. It can be seen that when the AC side voltage deviation... When the DC side voltage is positive, it is necessary to increase the DC side voltage; when the AC side voltage deviates... When the value is negative, the DC side voltage needs to be reduced.

[0051] Example 2:

[0052] A control device for flexible interconnection at the end of a low-voltage line based on communication-free operation, which can realize the control method for flexible interconnection at the end of a low-voltage line based on communication-free operation described in Embodiment 1, includes:

[0053] Voltage acquisition module: used to acquire the AC side voltage at the end of the low-voltage line and the current DC side voltage;

[0054] Judgment module: Used to determine whether the AC side voltage at the end of the low-voltage line is within the acceptable voltage range;

[0055] Deviation value determination module: used to determine the deviation value of AC side voltage from the qualified voltage range when the AC side voltage is not within the qualified voltage range; otherwise, no action is taken.

[0056] Command determination module: used to determine the DC side voltage command by combining the deviation values ​​of the current DC side voltage and AC side voltage from the qualified voltage range;

[0057] Voltage regulation module: Used to input DC side voltage commands into the voltage control loop, and adjust the DC voltage through the converter.

[0058] Example 3:

[0059] This invention also provides a control device for flexible interconnection at the end of a low-voltage line based on communication-free operation, which can realize the control method for flexible interconnection at the end of a low-voltage line based on communication-free operation described in Embodiment 1, including a processor and a storage medium;

[0060] The storage medium is used to store instructions;

[0061] The processor is configured to operate according to the instructions to perform the steps of the following method:

[0062] Obtain the AC side voltage at the end of the low-voltage line and the current DC side voltage;

[0063] Determine whether the AC voltage at the end of the low-voltage line is within the acceptable voltage range;

[0064] When the AC side voltage is outside the acceptable voltage range, determine the deviation value of the AC side voltage from the acceptable voltage range; otherwise, no action is taken.

[0065] The DC side voltage command is determined by combining the deviations of the current DC side voltage and AC side voltage from the qualified voltage range;

[0066] The DC-side voltage command is input into the voltage control loop, and the DC voltage is adjusted through the converter.

[0067] Example 4:

[0068] This invention also provides a computer-readable storage medium that can implement the flexible interconnection control method for low-voltage line terminals based on communication-free operation described in Embodiment 1. The medium stores a computer program that, when executed by a processor, performs the steps of the following method:

[0069] Obtain the AC side voltage at the end of the low-voltage line and the current DC side voltage;

[0070] Determine whether the AC voltage at the end of the low-voltage line is within the acceptable voltage range;

[0071] When the AC side voltage is outside the acceptable voltage range, determine the deviation value of the AC side voltage from the acceptable voltage range; otherwise, no action is taken.

[0072] The DC side voltage command is determined by combining the deviations of the current DC side voltage and AC side voltage from the qualified voltage range;

[0073] The DC-side voltage command is input into the voltage control loop, and the DC voltage is adjusted through the converter.

[0074] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0075] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0076] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0077] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for flexible interconnection at the end of a low-voltage line based on communication-free operation, characterized in that, include: Obtain the AC side voltage at the end of the low-voltage line and the current DC side voltage; Determine whether the AC voltage at the end of the low-voltage line is within the acceptable voltage range; When the AC side voltage is outside the acceptable voltage range, determine the deviation value of the AC side voltage from the acceptable voltage range; otherwise, no action is taken. Based on the deviations of the current DC-side voltage and AC-side voltage from the acceptable voltage range, the DC-side voltage command is determined; the calculation formula for the DC-side voltage command is as follows: ； in, This is a DC-side voltage command. This is the current DC-side voltage. This refers to the deviation of the AC side voltage from the acceptable voltage range. As a modulation parameter, f is modulated according to the load rate and resistance of the low-voltage line and the resistance of the DC line; The DC-side voltage command is input into the voltage control loop, and the DC voltage is adjusted through the converter.

2. The control method for flexible interconnection at the end of a low-voltage line based on communication-free operation according to claim 1, characterized in that, The AC side voltage at the end of the low-voltage line is obtained through the AC side voltage transformer of the converter.

3. The control method for flexible interconnection at the end of a low-voltage line based on non-communication as described in claim 1, characterized in that, The qualified voltage range includes the qualified voltage range at the receiving end of a single-phase 220V residential customer and the qualified voltage range at the client end of a three-phase 380V customer. Specifically, the qualified voltage range at the receiving end of a single-phase 220V residential customer is: the highest voltage during power consumption is not higher than 236V and the lowest voltage is not lower than 198V; the qualified voltage range at the client end of a three-phase 380V customer is: the highest voltage during power consumption is not higher than 407V and the lowest voltage is not lower than 353V.

4. The control method for flexible interconnection at the end of a low-voltage line based on non-communication as described in claim 1, characterized in that, The AC side voltage not being within the qualified voltage range includes two cases: AC side voltage > the upper limit of the qualified voltage or AC side voltage < the lower limit of the qualified voltage.

5. The control method for flexible interconnection at the end of a low-voltage line based on communication-free operation according to claim 4, characterized in that, The formula for calculating the deviation of the AC side voltage from the acceptable voltage range is as follows: ； in, AC side voltage, and These are the upper and lower limits of the acceptable voltage range, respectively. This represents the deviation of the AC side voltage from the acceptable voltage range.

6. A flexible interconnection control device for low-voltage line terminals without communication, characterized in that, include: Voltage acquisition module: used to acquire the AC side voltage at the end of the low-voltage line and the current DC side voltage; Judgment module: Used to determine whether the AC side voltage at the end of the low-voltage line is within the acceptable voltage range; Deviation value determination module: used to determine the deviation value of AC side voltage from the qualified voltage range when the AC side voltage is not within the qualified voltage range; otherwise, no action is taken. Command Determination Module: Used to determine the DC-side voltage command by combining the deviation values ​​of the current DC-side voltage and AC-side voltage from the acceptable voltage range; the calculation formula for the DC-side voltage command is: ； in, This is a DC-side voltage command. This is the current DC-side voltage. This refers to the deviation of the AC side voltage from the acceptable voltage range. As a modulation parameter, f is modulated according to the load rate and resistance of the low-voltage line and the resistance of the DC line; Voltage regulation module: Used to input DC side voltage commands into the voltage control loop, and adjust the DC voltage through the converter.

7. A flexible interconnection control device for low-voltage line terminals without communication, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1 to 5.

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