An adaptive flexible direct current black start control method and related device

Abstract

The application discloses a kind of self-adapting flexible direct current black start control method and related device, method includes: real-time determination corresponding bus voltage and active power of preset ac bus, preset ac bus is the ac bus that converter of load side in direct current transmission system is connected;It is judged whether bus voltage is greater than voltage reference value and active power is greater than power reference value, if yes, then based on closed-loop control, determine the target current reference value of outer loop control of direct current transmission system, if no, then based on open-loop control, determine the target current reference value of outer loop control of direct current transmission system;Based on target current reference value, generate impulse trigger signal in black start process.Solve the technical problem that existing flexible direct current black start control method is easy to cause high-frequency resonance.

Description

Technical Field

[0001] This application relates to the field of flexible DC transmission, and in particular to an adaptive flexible DC black-start control method and related apparatus. Background Technology

[0002] With the development of power grid transmission technology, various transmission technologies have emerged, among which flexible DC transmission technology is widely used.

[0003] like Figure 1 As shown, flexible DC uses converters based on fully controlled devices such as IGBTs, making it more flexible and controllable than conventional DC transmission systems. It can also perform phase commutation without relying on the grid, supply power to isolated grids, and has the ability to power grid black start.

[0004] Black start is an important method for self-healing of the power grid after a power outage. Existing flexible DC black start control methods are prone to resonance problems, such as high-frequency resonance. Therefore, providing an adaptive flexible DC black start control method to avoid high-frequency resonance in the flexible DC transmission system during the black start process, which threatens the safe operation of equipment and the power grid, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, this application provides an adaptive flexible DC black start control method and related device, which can effectively avoid high-frequency resonance in the flexible DC transmission system during the black start process, thereby solving the technical problem that existing flexible DC black start control methods are prone to causing high-frequency resonance.

[0006] The first aspect of this application provides an adaptive flexible DC black-start control method, comprising:

[0007] The bus voltage and active power corresponding to the preset AC bus are determined in real time. The preset AC bus is the AC bus connected to the converter on the load side of the DC transmission system.

[0008] Determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If yes, determine the target current reference value of the outer loop control of the DC transmission system based on closed-loop control. If no, determine the target current reference value of the outer loop control of the DC transmission system based on open-loop control.

[0009] Based on the target current reference value, a pulse trigger signal is generated during the black start process.

[0010] Optionally, the bus voltage and active power corresponding to the preset AC bus can be determined in real time, specifically including:

[0011] Real-time acquisition of bus voltage and bus current corresponding to preset AC bus;

[0012] The active power corresponding to the preset AC bus is calculated using the bus voltage and the bus current.

[0013] Optionally, it is determined whether the bus voltage is greater than a voltage reference value and whether the active power is greater than a power reference value. If yes, the target current reference value for the outer loop control of the DC transmission system is determined based on closed-loop control; if no, the target current reference value for the outer loop control of the DC transmission system is determined based on open-loop control. Specifically, this includes:

[0014] Determine the first current reference value of the outer loop AC voltage of the DC transmission system under open-loop control;

[0015] Determine the second current reference value of the outer loop AC voltage of the DC transmission system under closed-loop control;

[0016] Determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If yes, then the second current reference value is used as the target current reference value for the outer loop control of the DC transmission system. If no, then the first current reference value is used as the target current reference value for the outer loop control of the DC transmission system.

[0017] Optionally, based on the target current reference value, a pulse trigger signal is generated during the black start process, specifically including:

[0018] Based on the inner loop controller, a target voltage reference value corresponding to the target current reference value is generated;

[0019] Using the target voltage reference value, a modulation wave reference value for the control valve side voltage and a pulse trigger signal during the black start process are generated.

[0020] A second aspect of this application provides an adaptive flexible DC black-start control device, comprising:

[0021] The determining unit is used to determine the bus voltage and active power corresponding to the preset AC bus in real time. The preset AC bus is the AC bus connected to the converter on the load side of the DC transmission system.

[0022] The judgment unit is used to determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If so, the target current reference value of the outer loop control of the DC transmission system is determined based on closed-loop control. If not, the target current reference value of the outer loop control of the DC transmission system is determined based on open-loop control.

[0023] The generation unit is used to generate a pulse trigger signal during the black start process based on the target current reference value.

[0024] Optionally, the determining unit specifically includes:

[0025] The acquisition subunit is used to acquire the bus voltage and bus current corresponding to the preset AC bus in real time;

[0026] The calculation subunit is used to calculate the active power corresponding to the preset AC bus using the bus voltage and the bus current.

[0027] Optionally, the determination unit specifically includes:

[0028] The first determining subunit is used to determine the first current reference value of the outer loop AC voltage of the DC transmission system under open-loop control;

[0029] The second determining subunit is used to determine the second current reference value of the outer loop AC voltage of the DC transmission system under closed-loop control.

[0030] The judgment subunit is used to determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If yes, the second current reference value is used as the target current reference value for the outer loop control of the DC transmission system. If no, the first current reference value is used as the target current reference value for the outer loop control of the DC transmission system.

[0031] Optionally, the generation unit specifically includes:

[0032] The first generation subunit is used to generate the target voltage reference value corresponding to the target current reference value based on the inner loop controller;

[0033] The second generation subunit is used to generate a modulation wave reference value for the control valve side voltage and a pulse trigger signal during the black start process using the target voltage reference value.

[0034] A third aspect of this application provides an adaptive flexible DC black-start control device, including a processor and a memory;

[0035] The memory is used to store program code and transmit the program code to the processor;

[0036] The processor is configured to execute any of the adaptive flexible DC black-start control methods described in the first aspect according to instructions in the program code.

[0037] A fourth aspect of this application provides a storage medium for storing program code for executing any of the adaptive flexible DC black-start control methods described in the first aspect.

[0038] As can be seen from the above technical solutions, this application has the following advantages:

[0039] The adaptive flexible DC black-start control method in this application includes: determining in real time the bus voltage and active power corresponding to a preset AC bus, wherein the preset AC bus is the AC bus connected to the converter on the load side of the DC transmission system; determining whether the bus voltage is greater than a voltage reference value and whether the active power is greater than a power reference value; if so, determining the target current reference value of the outer loop control of the DC transmission system based on closed-loop control; if not, determining the target current reference value of the outer loop control of the DC transmission system based on open-loop control; and generating a pulse trigger signal during the black-start process based on the target current reference value.

[0040] In this application, in order to reduce high-frequency resonance during black start of flexible DC transmission systems, the bus voltage and active power of the AC bus are used as criteria. Under the premise that neither of them is greater than the corresponding reference value, the target current reference value of the outer loop control is determined through open-loop control. When both are greater than the corresponding reference value, the target current reference value of the outer loop control is determined through closed-loop control. This automatically determines the black start control of the flexible DC transmission system under load and unload conditions, realizes the adaptive switching between open-loop and closed-loop AC voltage control, avoids the risk of high-frequency resonance, and solves the technical problem that existing flexible DC black start control methods are prone to causing high-frequency resonance. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the structure of a flexible DC transmission system;

[0043] Figure 2 This is a flowchart illustrating an embodiment of an adaptive flexible DC black-start control method according to this application.

[0044] Figure 3 This is a schematic diagram illustrating the calculation of active power in an embodiment of this application;

[0045] Figure 4 This is a schematic diagram of the control of the outer loop AC voltage of the DC transmission system in the open loop control embodiment of this application;

[0046] Figure 5 This is a schematic diagram of the control of the outer loop AC voltage of the DC transmission system in the embodiment of this application during closed-loop control;

[0047] Figure 6This is a schematic diagram illustrating the calculation of the target current reference value for the outer loop control of the DC transmission system in this application embodiment. Figure 1 ;

[0048] Figure 7 This is a schematic diagram illustrating the calculation of the target current reference value for the outer loop control of the DC transmission system in this application embodiment. Figure 2 ;

[0049] Figure 8 This is a schematic diagram of the inner loop controller in an embodiment of this application;

[0050] Figure 9 This is a schematic diagram of the structure of an adaptive flexible DC black-start control device according to an embodiment of this application. Detailed Implementation

[0051] This application provides an adaptive flexible DC black-start control method and related apparatus, which solves the technical problem that existing flexible DC black-start control methods are prone to causing high-frequency resonance.

[0052] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0053] The first aspect of this application provides an embodiment of an adaptive flexible DC black-start control method.

[0054] Please see Figure 2 The following is a flowchart illustrating an embodiment of an adaptive flexible DC black-start control method in this application.

[0055] The adaptive flexible DC black-start control method in this embodiment includes:

[0056] Step 201: Determine the bus voltage and active power corresponding to the preset AC bus in real time. The preset AC bus is the AC bus connected to the converter on the load side of the DC transmission system.

[0057] It is understandable that, such as Figure 2 As shown, in this embodiment, the converter on the load side is converter 2 in the figure, and step 201 is to determine the bus voltage and active power corresponding to the AC bus connected to converter 2.

[0058] Specifically, the bus voltage and active power corresponding to the preset AC bus are determined in real time, including:

[0059] Real-time acquisition of bus voltage and bus current corresponding to preset AC bus;

[0060] Calculate the active power corresponding to the preset AC bus using the bus voltage and bus current.

[0061] It should be noted that when calculating active power using bus voltage and bus current, it is first necessary to perform a Parker transformation (also known as a dq transformation) on the bus voltage and bus current, that is, to perform a transformation on the collected bus voltages Uga, Ugb, and Ugc. Figure 3 The Parker transformation shown on the left side of the diagram yields voltages Ud and Uq. Simultaneously, the collected bus currents Iga, Igb, and Igc are processed... Figure 3 The Parker transformation shown in the middle structure yields currents Id and Iq, which are then used to calculate voltages Ud, Uq, Id, and Iq based on... Figure 3 The right-hand structure in the calculation pre-sets the active power Ps corresponding to the AC bus.

[0062] Step 202: Determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If yes, determine the target current reference value of the outer loop control of the DC transmission system based on closed-loop control. If no, determine the target current reference value of the outer loop control of the DC transmission system based on open-loop control.

[0063] To reduce high-frequency resonance during black start of the flexible DC transmission system, this embodiment uses the bus voltage and active power of the AC bus as criteria. Under the premise that neither of them is greater than the corresponding reference value, the target current reference value of the outer loop control is determined by open-loop control. When both of them are greater than the corresponding reference value, the target current reference value of the outer loop control is determined by closed-loop control, thus automatically judging the black start control of the flexible DC transmission system under load and unload conditions.

[0064] Therefore, in this embodiment, it is determined whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If so, the target current reference value for the outer loop control of the DC transmission system is determined based on closed-loop control; otherwise, the target current reference value for the outer loop control of the DC transmission system is determined based on open-loop control. Specifically, this includes:

[0065] Determine the first current reference value of the outer loop AC voltage of the DC transmission system under open-loop control;

[0066] Determine the second current reference value of the outer loop AC voltage of the DC transmission system under closed-loop control;

[0067] Determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If yes, the second current reference value is used as the target current reference value for the outer loop control of the DC transmission system. If no, the first current reference value is used as the target current reference value for the outer loop control of the DC transmission system.

[0068] When the bus voltage (i.e., Ugrms in the figure, where rms represents the effective value and Ugrms represents the effective value of the bus voltage) and active power (i.e. Figure 3 and Figure 6 , Figure 7 When the Ps values ​​are not all greater than the corresponding reference values, the flexible DC transmission system is in the unloaded stage during black start, posing a significant risk of high-frequency resonance. The target current reference value for the outer loop control of the DC transmission system is determined based on open-loop control and frequency control. Figure 4 The diagram illustrates the control of the outer-loop AC voltage of a DC transmission system under open-loop control. Through the control of the outer-loop AC voltage and frequency of the flexible DC transmission system, the first current reference values ​​(i.e., the target current reference values ​​at this time) idref1 and iqref1 are generated. Open-loop control, when not under load, can achieve the target control voltage while reducing the control system link delay increased by closed-loop control.

[0069] When both the bus voltage and active power exceed the corresponding reference values, the flexible DC transmission system enters the load-bearing stage during black start, at which point it can transition to... Figure 5 The closed-loop control shown generates the second current reference values ​​(i.e., the target current reference values ​​at this time) idref2 and iqref2 for the outer loop control based on the closed-loop control.

[0070] With the help of Figure 6 and Figure 7 The AC voltage open-loop control and closed-loop control selector controller shown in the figure automatically selects the target current reference value for the outer loop control by judging the bus voltage and active power of the AC bus.

[0071] Step 203: Based on the target current reference value, generate a pulse trigger signal during the black start process.

[0072] Understandably, based on the target current reference value, a pulse trigger signal is generated during the black start process, specifically including:

[0073] Based on the inner loop controller, a target voltage reference value corresponding to the target current reference value is generated;

[0074] Using the target voltage reference value, a modulation wave reference value for the control valve side voltage and a pulse trigger signal during the black start process are generated.

[0075] Specifically, in this embodiment, after the following... Figure 8The inner loop controller shown generates target voltage reference values ​​Udref and Uqref for the dq axis. Finally, after passing through the dq axis inverse transformation stage, it generates a modulated wave reference value for the control valve side voltage and generates a pulse trigger signal (i.e., the pulse trigger signal during the black start process) for the control of the next stage converter valve.

[0076] In this embodiment, in order to reduce the high-frequency resonance during the black start of the flexible DC transmission system, the bus voltage and active power of the AC bus are used as criteria. Under the premise that neither of them is greater than the corresponding reference value, the target current reference value of the outer loop control is determined by open-loop control. When both are greater than the corresponding reference value, the target current reference value of the outer loop control is determined by closed-loop control. The system automatically judges the black start control of the flexible DC transmission system under load and unload conditions, realizes the adaptive switching between open-loop and closed-loop AC voltage control, avoids the risk of high-frequency resonance, and solves the technical problem that the existing flexible DC black start control method is prone to causing high-frequency resonance.

[0077] The second aspect of this application provides an embodiment of an adaptive flexible DC black-start control device.

[0078] Please see Figure 9 The present application provides a schematic diagram of the structure of an adaptive flexible DC black start control device.

[0079] An adaptive flexible DC black-start control device in this embodiment includes:

[0080] The determination unit is used to determine the bus voltage and active power corresponding to the preset AC bus in real time. The preset AC bus is the AC bus connected to the converter on the load side of the DC transmission system.

[0081] The judgment unit is used to determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If so, the target current reference value of the outer loop control of the DC transmission system is determined based on the closed loop control. If not, the target current reference value of the outer loop control of the DC transmission system is determined based on the open loop control.

[0082] The generation unit is used to generate a pulse trigger signal during the black start process based on the target current reference value.

[0083] Optionally, determining the unit specifically includes:

[0084] The acquisition subunit is used to acquire the bus voltage and bus current corresponding to the preset AC bus in real time;

[0085] The calculation subunit is used to calculate the active power corresponding to a preset AC bus using the bus voltage and bus current.

[0086] Optionally, the judgment unit specifically includes:

[0087] The first determining subunit is used to determine the first current reference value of the outer loop AC voltage of the DC transmission system under open-loop control;

[0088] The second determining subunit is used to determine the second current reference value of the outer loop AC voltage of the DC transmission system under closed-loop control;

[0089] The judgment sub-unit is used to determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If so, the second current reference value is used as the target current reference value for the outer loop control of the DC transmission system. If not, the first current reference value is used as the target current reference value for the outer loop control of the DC transmission system.

[0090] Optionally, the generating unit specifically includes:

[0091] The first generation subunit is used to generate the target voltage reference value corresponding to the target current reference value based on the inner loop controller.

[0092] The second generation subunit is used to generate a modulation wave reference value for the control valve side voltage and a pulse trigger signal during the black start process using the target voltage reference value.

[0093] In this embodiment, in order to reduce the high-frequency resonance during the black start of the flexible DC transmission system, the bus voltage and active power of the AC bus are used as criteria. Under the premise that neither of them is greater than the corresponding reference value, the target current reference value of the outer loop control is determined by open-loop control. When both are greater than the corresponding reference value, the target current reference value of the outer loop control is determined by closed-loop control. The system automatically judges the black start control of the flexible DC transmission system under load and unload conditions, realizes the adaptive switching between open-loop and closed-loop AC voltage control, avoids the risk of high-frequency resonance, and solves the technical problem that the existing flexible DC black start control method is prone to causing high-frequency resonance.

[0094] The third aspect of this application provides an embodiment of an adaptive flexible DC black-start control device.

[0095] An adaptive flexible DC black-start control device includes a processor and a memory; the memory is used to store program code and transfer the program code to the processor; the processor is used to execute an adaptive flexible DC black-start control method according to the instructions in the program code.

[0096] The fourth aspect of this application provides an embodiment of a storage medium.

[0097] A storage medium for storing program code for executing an adaptive flexible DC black-start control method of the first aspect.

[0098] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described apparatus and unit can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0099] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another power grid network to be installed, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0100] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0101] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0102] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0103] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A self-adapting flexible HVDC black start control method, characterized in that, include: The bus voltage and active power corresponding to the preset AC bus are determined in real time. The preset AC bus is the AC bus connected to the converter on the load side of the DC transmission system. Determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If yes, determine the target current reference value of the outer loop control of the DC transmission system based on closed-loop control. If no, determine the target current reference value of the outer loop control of the DC transmission system based on open-loop control. Based on the target current reference value, a pulse trigger signal is generated during the black start process; Determine whether the bus voltage is greater than a voltage reference value and whether the active power is greater than a power reference value. If yes, determine the target current reference value for the outer loop control of the DC transmission system based on closed-loop control. If no, determine the target current reference value for the outer loop control of the DC transmission system based on open-loop control. Specifically, this includes: Determine the first current reference value of the outer loop AC voltage of the DC transmission system under open-loop control; Determine the second current reference value of the outer loop AC voltage of the DC transmission system under closed-loop control; Determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If yes, then the second current reference value is used as the target current reference value for the outer loop control of the DC transmission system. If no, then the first current reference value is used as the target current reference value for the outer loop control of the DC transmission system.

2. The adaptive flexible HVDC black-start control method of claim 1, wherein, Real-time determination of the bus voltage and active power corresponding to the preset AC bus, specifically including: Real-time acquisition of bus voltage and bus current corresponding to preset AC bus; The active power corresponding to the preset AC bus is calculated using the bus voltage and the bus current.

3. The adaptive flexible HVDC black start control method of claim 1, wherein, Based on the target current reference value, a pulse trigger signal is generated during the black start process, specifically including: Based on the inner loop controller, a target voltage reference value corresponding to the target current reference value is generated; Using the target voltage reference value, a modulation wave reference value for the control valve side voltage and a pulse trigger signal during the black start process are generated.

4. An adaptive flexible HVDC black start control apparatus, characterized by, include: The determining unit is used to determine the bus voltage and active power corresponding to the preset AC bus in real time. The preset AC bus is the AC bus connected to the converter on the load side of the DC transmission system. The judgment unit is used to determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If so, the target current reference value of the outer loop control of the DC transmission system is determined based on closed-loop control. If not, the target current reference value of the outer loop control of the DC transmission system is determined based on open-loop control. The generation unit is used to generate a pulse trigger signal during the black start process based on the target current reference value; The judgment unit specifically includes: The first determining subunit is used to determine the first current reference value of the outer loop AC voltage of the DC transmission system under open-loop control; The second determining subunit is used to determine the second current reference value of the outer loop AC voltage of the DC transmission system under closed-loop control. The judgment subunit is used to determine whether the bus voltage is greater than the voltage reference value and whether the active power is greater than the power reference value. If yes, the second current reference value is used as the target current reference value for the outer loop control of the DC transmission system. If no, the first current reference value is used as the target current reference value for the outer loop control of the DC transmission system.

5. The adaptive flexible HV black start control device of claim 4, wherein, The determining unit specifically includes: The acquisition subunit is used to acquire the bus voltage and bus current corresponding to the preset AC bus in real time; The calculation subunit is used to calculate the active power corresponding to the preset AC bus using the bus voltage and the bus current.

6. The adaptive flexible HV black start control device of claim 4, wherein, The generation unit specifically includes: The first generation subunit is used to generate the target voltage reference value corresponding to the target current reference value based on the inner loop controller; The second generation subunit is used to generate a modulation wave reference value for the control valve side voltage and a pulse trigger signal during the black start process using the target voltage reference value.

7. An adaptive flexible HVDC black start control device, characterized by, Including the processor and memory; The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the adaptive flexible DC black-start control method according to any one of claims 1 to 3 according to the instructions in the program code.

8. A storage medium, characterized by The storage medium is used to store program code for executing the adaptive flexible DC black-start control method according to any one of claims 1 to 3.

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