Method and device for controlling net-forming type flexible direct current converter

Abstract

The invention provides a control method and device of a net-forming type flexible direct current converter. And calculating the phase angle of the grid-connected point according to the active power actual value of the grid-forming flexible direct-current converter and the voltage actual value of the grid-connected point. And calculating the current reference value feed-forward quantity of the net-forming flexible direct-current converter according to the direct-current voltage actual value of the net-forming flexible direct-current converter. And according to the phase angle of the grid-connected point and the current reference value feed-forward quantity, controlling the grid-forming type flexible direct current converter. According to the technical scheme provided by the invention, stable control of alternating-current side current sharing and direct-current side voltage sharing of the multiple converter valve groups can be ensured, and automatic and accurate power distribution of the converter valve groups can be realized without manual intervention under complex working conditions such as random fluctuation of new energy power generation power, that is, the disturbance resistance is strong, and the efficiency is high. Wide-range stable control of the power grid intensity can be realized, the reliability is high, and the reliability of the flexible direct-current power transmission system is further improved.

Description

Technical Field

[0001] This application relates to the field of flexible DC transmission technology, specifically to a control method and device for a grid-type flexible DC converter. Background Technology

[0002] The integration of new energy power generation into the power system via voltage source converters leads to a reduction in inertia, damping, and frequency and voltage regulation capabilities. To ensure stable power system operation, control strategies with voltage and frequency support capabilities have become a current research hotspot. For voltage source converters, related technologies typically employ droop control and Virtual Synchronous Generator (VSG) control. However, with increasing transmission capacity and distance, flexible DC transmission systems are designed with multi-station parallel and valve group series structures. A key challenge is achieving AC-side current sharing, DC-side voltage sharing, and coordinated control among converter valve groups to ensure stable operation of the flexible DC transmission system under wide-range grid intensity conditions.

[0003] Related technologies typically select one converter valve group for grid-connected control, while other converter valve groups adopt grid-following control. However, this approach struggles to achieve automatic power distribution among the converter valve groups when dealing with fluctuations in renewable energy power, potentially leading to overvoltage in one converter valve group and affecting the stable operation of the flexible DC transmission system. In other words, the control methods provided by these technologies have low reliability and are prone to causing unstable operation of the flexible DC transmission system. Summary of the Invention

[0004] To address the problems in the prior art, this application provides a control method and apparatus for a grid-type flexible DC converter.

[0005] Firstly, this application provides a control method for a grid-type flexible DC converter, which may include: The phase angle at the grid connection point is calculated based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value at the grid connection point.

[0006] Calculate the current reference value feedforward of the grid-type flexible DC converter based on the actual DC voltage value of the grid-type flexible DC converter.

[0007] The grid-type flexible DC converter is controlled based on the phase angle and current reference value feedforward of the grid connection point.

[0008] Furthermore, control methods also include: The actual voltage value at the grid connection point is subjected to Park transformation to obtain the actual d-axis voltage value and q-axis voltage value at the grid connection point.

[0009] The actual current values ​​of the grid-type flexible DC converter are subjected to Park transformation to obtain the actual d-axis current values ​​and q-axis current values ​​of the grid-type flexible DC converter.

[0010] In some possible implementations, the phase angle of the grid connection point is calculated based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value at the grid connection point, including: The difference between the active power reference value and the actual active power value of the grid-type flexible DC converter is used for proportional-integral control to obtain the angular frequency regulation of the grid-type flexible DC converter.

[0011] The difference between the actual q-axis voltage at the grid connection point and the reference q-axis voltage at the grid connection point is used for proportional-integral control to obtain the angular frequency correction of the grid-type flexible DC converter.

[0012] The angular frequency at the grid connection point is obtained by superimposing the angular frequency adjustment, angular frequency correction, and the angular frequency reference value of the grid-type flexible DC converter.

[0013] The phase angle of the grid connection point is obtained by integral control of the angular frequency of the grid connection point.

[0014] In other possible implementations, the current reference feedforward of the grid-type flexible DC converter is calculated based on the actual DC voltage value of the grid-type flexible DC converter, including: The difference between the DC voltage reference value and the actual DC voltage value of the grid-type flexible DC converter is used for proportional-integral control to obtain the current reference value feedforward.

[0015] In some other possible implementations, the grid-connected flexible DC converter is controlled based on the feedforward of the phase angle and current reference value at the grid connection point, including: The reference current value of the grid-type flexible DC converter is calculated based on the actual reactive power value of the grid-type flexible DC converter and the actual voltage value at the grid connection point.

[0016] The modulation voltage reference value of the grid-connected flexible DC converter is calculated based on the actual voltage value at the grid connection point, the current reference value of the grid-type flexible DC converter, and the current reference value feedforward.

[0017] The modulation signal is obtained by performing an inverse Parker transform on the modulation voltage reference value of the grid-type flexible DC converter based on the phase angle of the grid connection point.

[0018] The grid-type flexible DC converter is controlled based on the modulation signal.

[0019] Furthermore, based on the actual reactive power value of the grid-connected flexible DC converter and the actual voltage value at the grid connection point, the current reference value of the grid-connected flexible DC converter is calculated, including: The difference between the reactive power reference value and the actual reactive power value of the grid-type flexible DC converter is used for proportional-integral control to obtain the d-axis voltage correction value of the grid-type flexible DC converter. Then, the d-axis current reference value of the grid-type flexible DC converter is calculated based on the d-axis voltage correction value, the actual d-axis voltage value at the grid connection point, and the d-axis voltage reference value at the grid connection point.

[0020] The difference between the reference value of the q-axis voltage at the grid connection point and the actual value of the q-axis voltage at the grid connection point is used for proportional-integral control to obtain the reference value of the q-axis current of the grid-type flexible DC converter in a two-phase rotating coordinate system.

[0021] Optionally, the d-axis current reference value of the grid-type flexible DC converter satisfies:

[0022] in, This represents the reference value for the d-axis current of a grid-type flexible DC converter. This represents the d-axis voltage correction value for a grid-type flexible DC converter. This represents the d-axis voltage reference value at the grid connection point. This represents the actual d-axis voltage value at the grid connection point. This represents the proportionality coefficient. Represents the integral coefficient. s Represents a complex variable in the complex frequency domain.

[0023] For example, the modulation voltage reference value of the grid-connected flexible DC converter is calculated based on the actual voltage value at the grid connection point, the current reference value of the grid-connected flexible DC converter, and the current reference value feedforward, including: The d-axis current deviation of the grid-type flexible DC converter is calculated based on the d-axis current reference value, the actual d-axis voltage value, and the feedforward of the current reference value. The difference between the q-axis current reference value and the actual q-axis current value of the grid-type flexible DC converter is taken as the q-axis current deviation of the grid-type flexible DC converter.

[0024] Proportional-integral (PI) control is applied to the d-axis current deviation to obtain the first modulation voltage of the grid-type flexible DC-DC converter. Similarly, proportional-integral (PI) control is applied to the q-axis current deviation to obtain the first modulation voltage of the grid-type flexible DC-DC converter.

[0025] Calculate the second modulation voltage of the d-axis of the grid-type flexible DC converter based on the actual value of the q-axis current.

[0026] The reference value of the d-axis modulation voltage of the grid-type flexible DC converter is calculated based on the first modulation voltage, the second modulation voltage, and the actual value of the d-axis voltage. The reference value of the q-axis modulation voltage is also calculated based on the first modulation voltage, the second modulation voltage, and the actual value of the q-axis voltage.

[0027] Optionally, the d-axis current deviation of the grid-type flexible DC converter satisfies:

[0028] in, This represents the d-axis current deviation of a grid-type flexible DC converter. This represents the reference value for the d-axis current of a grid-type flexible DC converter. This represents the actual d-axis voltage value of a grid-type flexible DC converter. This represents the current reference value feedforward.

[0029] The d-axis modulation voltage reference value of the grid-type flexible DC converter satisfies:

[0030] in, This represents the reference value of the d-axis modulation voltage for a grid-type flexible DC converter. This represents the actual value of the d-axis voltage of the grid-type flexible DC converter. This represents the first modulation voltage on the d-axis of the grid-type flexible DC converter. This represents the second modulation voltage along the d-axis of the grid-type flexible DC converter, satisfying... , This represents the actual value of the q-axis current in a grid-type flexible DC converter.

[0031] The q-axis modulation voltage reference value of the grid-type flexible DC converter satisfies:

[0032] in, This represents the reference value for the q-axis modulation voltage of a grid-type flexible DC converter. This represents the actual value of the q-axis voltage of the grid-type flexible DC converter. This represents the first modulation voltage on the q-axis of the grid-type flexible DC converter. This represents the second modulation voltage of the q-axis of the grid-type flexible DC converter, which satisfies... ω represents the angular frequency of the AC system, and L represents the equivalent inductance of the grid-type flexible DC converter. This represents the actual value of the d-axis current of the grid-type flexible DC converter.

[0033] Secondly, this application provides a control device for a grid-type flexible DC converter, which may include: The first calculation module is used to calculate the phase angle of the grid connection point based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value of the grid connection point.

[0034] The second calculation module is used to calculate the current reference value feedforward of the grid-type flexible DC converter based on the actual value of the DC voltage of the grid-type flexible DC converter.

[0035] The control module is used to control the grid-connected flexible DC converter based on the feedforward amount of the phase angle and current reference value at the grid connection point.

[0036] Furthermore, the control device also includes a conversion module, which is specifically used for: The actual voltage value at the grid connection point is subjected to Park transformation to obtain the actual d-axis voltage value and q-axis voltage value at the grid connection point.

[0037] The actual current values ​​of the grid-type flexible DC converter are subjected to Park transformation to obtain the actual d-axis current values ​​and q-axis current values ​​of the grid-type flexible DC converter.

[0038] In some possible implementations, the first computation module is specifically used for: The difference between the active power reference value and the actual active power value of the grid-type flexible DC converter is used for proportional-integral control to obtain the angular frequency regulation of the grid-type flexible DC converter.

[0039] The difference between the actual q-axis voltage at the grid connection point and the reference q-axis voltage at the grid connection point is used for proportional-integral control to obtain the angular frequency correction of the grid-type flexible DC converter.

[0040] The angular frequency at the grid connection point is obtained by superimposing the angular frequency adjustment, angular frequency correction, and the angular frequency reference value of the grid-type flexible DC converter.

[0041] The phase angle of the grid connection point is obtained by integral control of the angular frequency of the grid connection point.

[0042] In some other possible implementations, the second computation module is specifically used for: The difference between the DC voltage reference value and the actual DC voltage value of the grid-type flexible DC converter is used for proportional-integral control to obtain the current reference value feedforward.

[0043] In some other possible implementations, the control module is specifically used for: The reference current value of the grid-type flexible DC converter is calculated based on the actual reactive power value of the grid-type flexible DC converter and the actual voltage value at the grid connection point.

[0044] The modulation voltage reference value of the grid-connected flexible DC converter is calculated based on the actual voltage value at the grid connection point, the current reference value of the grid-type flexible DC converter, and the current reference value feedforward.

[0045] The modulation signal is obtained by performing an inverse Parker transform on the modulation voltage reference value of the grid-type flexible DC converter based on the phase angle of the grid connection point.

[0046] The grid-type flexible DC converter is controlled based on the modulation signal.

[0047] Optionally, the control module is specifically used for: The difference between the reactive power reference value and the actual reactive power value of the grid-type flexible DC converter is used for proportional-integral control to obtain the d-axis voltage correction value of the grid-type flexible DC converter. Then, the d-axis current reference value of the grid-type flexible DC converter is calculated based on the d-axis voltage correction value, the actual d-axis voltage value at the grid connection point, and the d-axis voltage reference value at the grid connection point.

[0048] The difference between the reference value of the q-axis voltage at the grid connection point and the actual value of the q-axis voltage at the grid connection point is used for proportional-integral control to obtain the reference value of the q-axis current of the grid-type flexible DC converter in a two-phase rotating coordinate system.

[0049] For example, the d-axis current reference value of a grid-type flexible DC converter satisfies:

[0050] in, This represents the reference value for the d-axis current of a grid-type flexible DC converter. This represents the d-axis voltage correction value for a grid-type flexible DC converter. This represents the d-axis voltage reference value at the grid connection point. This represents the actual d-axis voltage value at the grid connection point. This represents the proportionality coefficient. Represents the integral coefficient. s Represents a complex variable in the complex frequency domain.

[0051] Optionally, the control module is specifically used for: The d-axis current deviation of the grid-type flexible DC converter is calculated based on the d-axis current reference value, the actual d-axis voltage value, and the feedforward of the current reference value. The difference between the q-axis current reference value and the actual q-axis current value of the grid-type flexible DC converter is taken as the q-axis current deviation of the grid-type flexible DC converter.

[0052] Proportional-integral (PI) control is applied to the d-axis current deviation to obtain the first modulation voltage of the grid-type flexible DC-DC converter. Similarly, proportional-integral (PI) control is applied to the q-axis current deviation to obtain the first modulation voltage of the grid-type flexible DC-DC converter.

[0053] Calculate the second modulation voltage of the d-axis of the grid-type flexible DC converter based on the actual value of the q-axis current.

[0054] The reference value of the d-axis modulation voltage of the grid-type flexible DC converter is calculated based on the first modulation voltage, the second modulation voltage, and the actual value of the d-axis voltage. The reference value of the q-axis modulation voltage is also calculated based on the first modulation voltage, the second modulation voltage, and the actual value of the q-axis voltage.

[0055] The d-axis current deviation of the grid-type flexible DC converter satisfies:

[0056] in, This represents the d-axis current deviation of a grid-type flexible DC converter. This represents the reference value for the d-axis current of a grid-type flexible DC converter. This represents the actual d-axis voltage value of a grid-type flexible DC converter. This represents the current reference value feedforward.

[0057] The d-axis modulation voltage reference value of the grid-type flexible DC converter satisfies:

[0058] in, This represents the reference value of the d-axis modulation voltage for a grid-type flexible DC converter. This represents the actual value of the d-axis voltage of the grid-type flexible DC converter. This represents the first modulation voltage on the d-axis of the grid-type flexible DC converter. This represents the second modulation voltage along the d-axis of the grid-type flexible DC converter, satisfying... , This represents the actual value of the q-axis current in a grid-type flexible DC converter.

[0059] The q-axis modulation voltage reference value of the grid-type flexible DC converter satisfies:

[0060] in, This represents the reference value for the q-axis modulation voltage of a grid-type flexible DC converter. This represents the actual value of the q-axis voltage of the grid-type flexible DC converter. This represents the first modulation voltage on the q-axis of the grid-type flexible DC converter. This represents the second modulation voltage of the q-axis of the grid-type flexible DC converter, which satisfies... ω represents the angular frequency of the AC system, and L represents the equivalent inductance of the grid-type flexible DC converter. This represents the actual value of the d-axis current of the grid-type flexible DC converter.

[0061] In another aspect, this application also provides a computer device, including: one or more processors.

[0062] A processor is used to execute one or more programs.

[0063] When one or more programs are executed by one or more processors, the control method described above is implemented.

[0064] Furthermore, this application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed, it implements the control method described above.

[0065] Compared with the prior art, the beneficial effects of this application are as follows: The control method for a grid-connected flexible DC converter provided in this application calculates the phase angle of the grid connection point based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value of the grid connection point. It also calculates the current reference feedforward of the grid-connected flexible DC converter based on the actual DC voltage value. Finally, it controls the grid-connected flexible DC converter based on the phase angle of the grid connection point and the current reference feedforward. The technical solution provided in this application can ensure stable control of current sharing on the AC side and voltage sharing on the DC side of multiple converter valve groups. Under complex operating conditions such as random fluctuations in new energy power generation, it can achieve automatic and accurate power allocation of each converter valve group without manual intervention. In other words, it has strong anti-disturbance capabilities, can achieve stable control over a wide range of grid strength, and has high reliability.

[0066] The technical solution provided in this application breaks through the dependence of traditional multi-converter valve group parallel operation on inter-valve communication and coordination. Under the premise of no inter-converter valve group interactive communication, it supports multiple converter valve groups to operate independently in their own network.

[0067] This application not only ensures stable control of AC-side current sharing and DC-side voltage sharing, but also avoids operational risks of flexible DC transmission systems caused by communication link failures, significantly improving the flexibility of the topology and control strategy of flexible DC transmission systems and providing greater control freedom.

[0068] This application can adapt to a wide range of power grid intensity variation scenarios, achieve stable operation under all operating conditions, and greatly improve the reliability of flexible DC transmission system operation. Attached Figure Description

[0069] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 This is a schematic structural diagram of a flexible DC transmission system in an embodiment of this application; Figure 2 This is a schematic flowchart of a control method for a grid-type flexible DC converter in an embodiment of this application; Figure 3 This is another schematic flowchart of the control method for a grid-type flexible DC converter in the embodiments of this application; Figure 4 This is a schematic structural diagram of a control device for a grid-type flexible DC converter in an embodiment of this application. Detailed Implementation

[0071] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0072] The terms "first," "second," etc., used in the specification, embodiments, claims, and drawings of this application are for distinguishing purposes only and should not be construed as indicating or implying relative importance or order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or apparatus is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0073] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0074] Example 1: This application provides a control method for a grid-type flexible DC converter. Considering factors such as technical feasibility, economics, maturity, and power device limitations, and taking an ±800kV, 8GW true bipolar topology (UHV) flexible DC transmission system as an example, this method is tailored to the ultra-high voltage (UHV) flexible DC transmission scenario. Figure 1 As shown, the flexible DC transmission system 100 may include a sending-end grid-type converter 10 and a receiving-end grid-type converter 20. The sending-end grid-type converter 10 includes a sending-end positive converter valve group 11 and a sending-end negative converter valve group 12. The sending-end positive converter valve group 11 includes voltage source converters VSC1 and VSC2; the sending-end negative converter valve group 12 includes voltage source converters VSC3 and VSC4.

[0075] Similarly, the receiving-end grid-type converter 20 includes a receiving-end positive converter valve group 21 and a receiving-end negative converter valve group 22; the receiving-end positive converter valve group 21 includes voltage source converters VSC5 and VSC6; the receiving-end negative converter valve group 22 includes voltage source converters VSC7 and VSC8.

[0076] In this system, the AC sides of voltage source converters VSC1 and VSC2 are connected in parallel to the same AC bus (i.e., AC bus BUS1), while the DC sides of VSC1 and VSC2 are connected in series, forming a single-pole DC circuit. Similarly, the AC sides of voltage source converters VSC5 and VSC6 are connected in parallel to the same AC bus (i.e., AC bus BUS2), and the DC sides of VSC5 and VSC6 are connected in series, also forming a single-pole DC circuit.

[0077] Similarly, the AC sides of voltage source converters VSC3 and VSC4 are connected in parallel to the same AC bus (i.e., AC bus BUS1), while the DC sides of VSC3 and VSC4 are connected in series, forming a single-pole DC circuit. The AC sides of voltage source converters VSC7 and VSC8 are also connected in parallel to the same AC bus (i.e., AC bus BUS2), forming a single-pole DC circuit as well.

[0078] AC bus BUS1 can be connected to AC system S1, and AC bus BUS2 can be connected to AC system S2.

[0079] Optionally, the voltage source converters VSC1, VSC2, VSC3, VSC4, VSC5, VSC7, and VSC8 mentioned above can all be grid-type flexible DC converters, etc. This application uses a grid-type flexible DC converter as an example for illustration.

[0080] like Figure 2 As shown, the control method 200 includes the following steps: Step S1: Calculate the phase angle of the grid connection point based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value of the grid connection point.

[0081] Step S2: Calculate the current reference value feedforward of the grid-type flexible DC converter based on the actual DC voltage value of the grid-type flexible DC converter.

[0082] Step S3: Control the grid-type flexible DC converter based on the phase angle and current reference value feedforward of the grid connection point.

[0083] Furthermore, the control method provided in this application embodiment also includes: Perform a Park transformation (abc / dq transformation) on the actual voltage value at the grid connection point to obtain the actual d-axis voltage value at the grid connection point. and actual value of q-axis voltage .

[0084] The actual current value of the grid-type flexible DC converter is obtained by performing a Parker transformation. and actual value of q-axis current .

[0085] In some possible implementations, the step S1 above, which calculates the phase angle of the grid connection point based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value at the grid connection point, may specifically include: refer to Figure 3 The active power reference value of the grid-type flexible DC converter The difference between the active power P of the grid-type flexible DC converter and the actual active power P is used for proportional-integral control (i.e., PI control) to obtain the angular frequency regulation of the grid-type flexible DC converter. .

[0086] The actual value of the q-axis voltage at the grid connection point q-axis voltage reference value at grid connection point The difference is used for proportional-integral control to obtain the angular frequency correction of the grid-type flexible DC converter. .

[0087] Adjust the angular frequency Angular frequency correction amount Angular frequency reference value of grid-type flexible DC converter Superposition yields the angular frequency at the grid connection point. .

[0088] angular frequency at the grid connection point Integral control is performed to obtain the phase angle at the grid connection point. .

[0089] In some other possible implementations, step S2 above, based on the actual value of the DC voltage of the grid-type flexible DC converter... Calculate the current reference feedforward of the grid-type flexible DC converter. ,include: refer to Figure 3 The DC voltage reference value of the grid-type flexible DC converter Actual DC voltage value of grid-type flexible DC converter The difference is used for proportional-integral control to obtain the current reference value feedforward quantity. .

[0090] In some other possible implementations, step S3 above involves controlling the grid-connected flexible DC converter based on the phase angle and current reference value feedforward at the grid connection point, including: refer to Figure 3 Based on the actual reactive power value Q of the grid-connected flexible DC converter and the actual voltage value at the grid connection point (reflected in... Figure 3 Actual value of d-axis voltage at the grid connection point and actual value of q-axis voltage Calculate the current reference value of the grid-type flexible DC converter (i.e., the d-axis current reference value of the grid-type flexible DC converter). and q-axis current reference value ).

[0091] Based on the actual voltage value of the grid connection point (i.e., the actual d-axis voltage value of the aforementioned grid connection point) and actual value of q-axis voltage ), the current reference value of the grid-type flexible DC converter (i.e., the d-axis current reference value mentioned above), and q-axis current reference value ) and current reference value feedforward Calculate the modulation voltage reference value of the grid-type flexible DC converter (reflected in) Figure 3 d-axis modulation voltage reference value of grid-type flexible DC converter and q-axis modulation voltage reference value ).

[0092] Based on the phase angle of the grid connection point The modulation voltage reference value (i.e., the d-axis modulation voltage reference value) for the grid-type flexible DC converter and q-axis modulation voltage reference value Perform an inverse Park transform (i.e., inverse Park transform, dq / abc transform) to obtain the modulated signal (i.e. Figure 3 The A, B, and C phase modulation voltages , , ).

[0093] The grid-type flexible DC converter can be controlled based on the modulation signal.

[0094] Furthermore, the above is based on the actual reactive power value Q of the grid-connected flexible DC converter and the actual voltage value at the grid connection point (including the actual d-axis voltage value). and actual value of q-axis voltage Calculate the current reference values ​​(including d-axis current reference values) for grid-type flexible DC converters. and q-axis current reference value Specifically, it can include: refer to Figure 3 The reactive power reference value of the grid-type flexible DC converter The difference between the reactive power Q of the grid-type flexible DC converter and the actual reactive power Q is used for proportional-integral control to obtain the d-axis voltage correction of the grid-type flexible DC converter. And based on the d-axis voltage correction amount of the grid-type flexible DC converter. Actual value of d-axis voltage at the grid connection point and the d-axis voltage reference value of the grid connection point (Choose 1) Calculate the reference value of the d-axis current of the grid-type flexible DC converter. .

[0095] The q-axis voltage reference value of the grid connection point (Can be taken as 0) and the actual value of the q-axis voltage at the grid connection point The difference is used for proportional-integral control to obtain the q-axis current reference value of the grid-type flexible DC converter in a two-phase rotating coordinate system. .

[0096] Optionally, the d-axis current reference value of the grid-type flexible DC converter satisfies:

[0097] in, This represents the reference value for the d-axis current of a grid-type flexible DC converter. This represents the d-axis voltage correction value for a grid-type flexible DC converter. This represents the d-axis voltage reference value at the grid connection point. This represents the actual d-axis voltage value at the grid connection point. This represents the proportionality coefficient. Represents the integral coefficient. s Represents a complex variable in the complex frequency domain.

[0098] For example, based on the actual voltage value at the grid connection point, the current reference value of the grid-connected flexible DC converter, and the current reference value feedforward. Calculate the modulation voltage reference value of the grid-type flexible DC converter (i.e., the d-axis modulation voltage reference value of the grid-type flexible DC converter). and q-axis modulation voltage reference value ),include: refer to Figure 3 Based on the d-axis current reference value of the grid-type flexible DC converter Actual value of d-axis voltage and current reference value feedforward Calculate the d-axis current deviation of a grid-type flexible DC converter The q-axis current reference value of the grid-type flexible DC converter. Actual q-axis current of grid-type flexible DC converter The difference is used as the q-axis current deviation of the grid-type flexible DC converter. .

[0099] d-axis current deviation Proportional-integral control is performed to obtain the first modulation voltage of the d-axis of the grid-type flexible DC converter. q-axis current deviation Proportional-integral control is performed to obtain the first modulation voltage of the q-axis of the grid-type flexible DC converter. .

[0100] Based on the actual value of the q-axis current of the grid-type flexible DC converter Calculate the second modulation voltage of the d-axis of the grid-type flexible DC converter. Based on the actual value of the d-axis current of the grid-type flexible DC converter. Calculate the q-axis second modulation voltage of the grid-type flexible DC converter .

[0101] Based on the first modulation voltage of the d-axis of the grid-type flexible DC converter d-axis second modulation voltage and actual value of d-axis voltage Calculate the d-axis modulation voltage reference value for a grid-type flexible DC converter. Based on the q-axis first modulation voltage of the grid-type flexible DC converter. q-axis second modulation voltage and actual value of q-axis voltage Calculate the reference value of the q-axis modulation voltage for a grid-type flexible DC converter. .

[0102] Optionally, the d-axis current deviation of the grid-type flexible DC converter satisfies:

[0103] in, This represents the d-axis current deviation of a grid-type flexible DC converter. This represents the reference value for the d-axis current of a grid-type flexible DC converter. This represents the actual d-axis voltage value of a grid-type flexible DC converter. This represents the current reference value feedforward.

[0104] The d-axis modulation voltage reference value of the grid-type flexible DC converter satisfies:

[0105] in, This represents the reference value of the d-axis modulation voltage for a grid-type flexible DC converter. This represents the actual value of the d-axis voltage of the grid-type flexible DC converter. This represents the first modulation voltage on the d-axis of the grid-type flexible DC converter. This represents the second modulation voltage along the d-axis of the grid-type flexible DC converter, satisfying... , This represents the actual value of the q-axis current in a grid-type flexible DC converter.

[0106] The q-axis modulation voltage reference value of the grid-type flexible DC converter satisfies:

[0107] in, This represents the reference value for the q-axis modulation voltage of a grid-type flexible DC converter. This represents the actual value of the q-axis voltage of the grid-type flexible DC converter. This represents the first modulation voltage on the q-axis of the grid-type flexible DC converter. This represents the second modulation voltage of the q-axis of the grid-type flexible DC converter, which satisfies... ω represents the angular frequency of the AC system, and L represents the equivalent inductance of the grid-type flexible DC converter. This represents the actual value of the d-axis current of the grid-type flexible DC converter.

[0108] Example 2: Based on the same inventive concept, this application also provides a control device for a grid-type flexible DC converter. Considering factors such as technical feasibility, economics, maturity, and limitations of power device capabilities, and taking an ±800kV, 8GW true bipolar topology (ultra-high voltage) flexible DC transmission system as an example, this application provides a detailed description as described above. Figure 1 The embodiments in this application will not be described in detail.

[0109] like Figure 4 As shown, the control device 300 includes: The first calculation module 301 is used to calculate the phase angle of the grid connection point based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value of the grid connection point.

[0110] The second calculation module 302 is used to calculate the current reference value feedforward of the grid-type flexible DC converter based on the actual value of the DC voltage of the grid-type flexible DC converter.

[0111] The control module 303 is used to control the grid-type flexible DC converter based on the feedforward amount of the phase angle and current reference value of the grid connection point.

[0112] Furthermore, the control device provided in this application also includes a conversion module, which is specifically used for: Perform a Park transformation (abc / dq transformation) on the actual voltage value at the grid connection point to obtain the actual d-axis voltage value at the grid connection point. and actual value of q-axis voltage .

[0113] The actual current value of the grid-type flexible DC converter is obtained by performing a Parker transformation. and actual value of q-axis current .

[0114] In some possible implementations, the first computing module 301 is specifically used for: refer to Figure 3 The active power reference value of the grid-type flexible DC converter The difference between the active power P of the grid-type flexible DC converter and the actual active power P is used for proportional-integral control (i.e., PI control) to obtain the angular frequency regulation of the grid-type flexible DC converter. .

[0115] The actual value of the q-axis voltage at the grid connection point q-axis voltage reference value at grid connection point The difference is used for proportional-integral control to obtain the angular frequency correction of the grid-type flexible DC converter. .

[0116] Adjust the angular frequency Angular frequency correction amount Angular frequency reference value of grid-type flexible DC converter Superposition yields the angular frequency at the grid connection point. .

[0117] angular frequency at the grid connection point Integral control is performed to obtain the phase angle at the grid connection point. .

[0118] In some other possible implementations, the second computing module 302 is specifically used for: refer to Figure 3 The DC voltage reference value of the grid-type flexible DC converter Actual DC voltage value of grid-type flexible DC converter The difference is used for proportional-integral control to obtain the current reference value feedforward quantity. .

[0119] In some other possible implementations, the control module 303 is specifically used for: refer to Figure 3 Based on the actual reactive power value Q of the grid-connected flexible DC converter and the actual voltage value at the grid connection point (reflected in... Figure 3 Actual value of d-axis voltage at the grid connection point and actual value of q-axis voltage Calculate the current reference value of the grid-type flexible DC converter (i.e., the d-axis current reference value of the grid-type flexible DC converter). and q-axis current reference value ).

[0120] Based on the actual voltage value of the grid connection point (i.e., the actual d-axis voltage value of the aforementioned grid connection point) and actual value of q-axis voltage ), the current reference value of the grid-type flexible DC converter (i.e., the d-axis current reference value mentioned above), and q-axis current reference value ) and current reference value feedforward Calculate the modulation voltage reference value of the grid-type flexible DC converter (reflected in) Figure 3 d-axis modulation voltage reference value of grid-type flexible DC converter and q-axis modulation voltage reference value ).

[0121] Based on the phase angle of the grid connection point The modulation voltage reference value (i.e., the d-axis modulation voltage reference value) for the grid-type flexible DC converter and q-axis modulation voltage reference value Perform an inverse Park transform (i.e., inverse Park transform, dq / abc transform) to obtain the modulated signal (i.e. Figure 3 The A, B, and C phase modulation voltages , , ).

[0122] The grid-type flexible DC converter can be controlled based on the modulation signal.

[0123] Optionally, the control module 303 is specifically used for: refer to Figure 3 The reactive power reference value of the grid-type flexible DC converter The difference between the reactive power Q of the grid-type flexible DC converter and the actual reactive power Q is used for proportional-integral control to obtain the d-axis voltage correction of the grid-type flexible DC converter. And based on the d-axis voltage correction amount of the grid-type flexible DC converter. Actual value of d-axis voltage at the grid connection point and the d-axis voltage reference value of the grid connection point (Choose 1) Calculate the reference value of the d-axis current of the grid-type flexible DC converter. .

[0124] The q-axis voltage reference value of the grid connection point (Can be taken as 0) and the actual value of the q-axis voltage at the grid connection point The difference is used for proportional-integral control to obtain the q-axis current reference value of the grid-type flexible DC converter in a two-phase rotating coordinate system. .

[0125] Optionally, the d-axis current reference value of the grid-type flexible DC converter satisfies:

[0126] in, This represents the reference value for the d-axis current of a grid-type flexible DC converter. This represents the d-axis voltage correction value for a grid-type flexible DC converter. This represents the d-axis voltage reference value at the grid connection point. This represents the actual d-axis voltage value at the grid connection point. This represents the proportionality coefficient. Represents the integral coefficient. s Represents a complex variable in the complex frequency domain.

[0127] Optionally, the control module 303 is specifically used for: refer to Figure 3 Based on the d-axis current reference value of the grid-type flexible DC converter Actual value of d-axis voltage and current reference value feedforward Calculate the d-axis current deviation of a grid-type flexible DC converter The q-axis current reference value of the grid-type flexible DC converter. Actual q-axis current of grid-type flexible DC converter The difference is used as the q-axis current deviation of the grid-type flexible DC converter. .

[0128] d-axis current deviation Proportional-integral control is performed to obtain the first modulation voltage of the d-axis of the grid-type flexible DC converter. q-axis current deviation Proportional-integral control is performed to obtain the first modulation voltage of the q-axis of the grid-type flexible DC converter. .

[0129] Based on the actual value of the q-axis current of the grid-type flexible DC converter Calculate the second modulation voltage of the d-axis of the grid-type flexible DC converter. Based on the actual value of the d-axis current of the grid-type flexible DC converter. Calculate the q-axis second modulation voltage of the grid-type flexible DC converter .

[0130] Based on the first modulation voltage of the d-axis of the grid-type flexible DC converter d-axis second modulation voltage and actual value of d-axis voltage Calculate the d-axis modulation voltage reference value for a grid-type flexible DC converter. Based on the q-axis first modulation voltage of the grid-type flexible DC converter. q-axis second modulation voltage and actual value of q-axis voltage Calculate the reference value of the q-axis modulation voltage for a grid-type flexible DC converter. .

[0131] Optionally, the d-axis current deviation of the grid-type flexible DC converter satisfies:

[0132] in, This represents the d-axis current deviation of a grid-type flexible DC converter. This represents the reference value for the d-axis current of a grid-type flexible DC converter. This represents the actual d-axis voltage value of a grid-type flexible DC converter. This represents the current reference value feedforward.

[0133] The d-axis modulation voltage reference value of the grid-type flexible DC converter satisfies:

[0134] in, This represents the reference value of the d-axis modulation voltage for a grid-type flexible DC converter. This represents the actual value of the d-axis voltage of the grid-type flexible DC converter. This represents the first modulation voltage on the d-axis of the grid-type flexible DC converter. This represents the second modulation voltage along the d-axis of the grid-type flexible DC converter, satisfying... , This represents the actual value of the q-axis current in a grid-type flexible DC converter.

[0135] The q-axis modulation voltage reference value of the grid-type flexible DC converter satisfies:

[0136] in, This represents the reference value for the q-axis modulation voltage of a grid-type flexible DC converter. This represents the actual value of the q-axis voltage of the grid-type flexible DC converter. This represents the first modulation voltage on the q-axis of the grid-type flexible DC converter. This represents the second modulation voltage of the q-axis of the grid-type flexible DC converter, which satisfies... ω represents the angular frequency of the AC system, and L represents the equivalent inductance of the grid-type flexible DC converter. This represents the actual value of the d-axis current of the grid-type flexible DC converter.

[0137] Example 3: Based on the same inventive concept, this application also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the control method provided in the above embodiments.

[0138] Example 4: Based on the same inventive concept, this application also provides a computer-readable storage medium, specifically a computer-readable storage medium (Memory). A computer-readable storage medium is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the control method provided in the above embodiments.

[0139] Those skilled in the art will understand that the embodiments of the application can be provided as a method, system, or computer program product. Therefore, the application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the application can take the form of a computer program product implemented 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.

[0140] The application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the 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.

[0141] 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.

[0142] 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.

[0143] The above are merely examples of the application and are not intended to limit the application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the application shall be included within the scope of the claims of the pending application.

Claims

1. A control method for a grid-type flexible DC converter, characterized in that, include: The phase angle of the grid connection point is calculated based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value of the grid connection point. Calculate the current reference value feedforward of the grid-type flexible DC converter based on the actual value of the DC voltage of the grid-type flexible DC converter; The grid-type flexible DC converter is controlled based on the phase angle of the grid connection point and the feedforward amount of the current reference value.

2. The control method according to claim 1, characterized in that, The control method further includes: The actual voltage value at the grid connection point is subjected to Park transformation to obtain the actual d-axis voltage value and the actual q-axis voltage value at the grid connection point; The actual current values ​​of the grid-type flexible DC converter are subjected to Park transformation to obtain the actual d-axis current values ​​and q-axis current values ​​of the grid-type flexible DC converter.

3. The control method according to claim 2, characterized in that, The calculation of the phase angle of the grid connection point based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value of the grid connection point includes: The difference between the active power reference value and the actual active power value of the grid-type flexible DC converter is used for proportional-integral control to obtain the angular frequency adjustment amount of the grid-type flexible DC converter. The difference between the actual q-axis voltage value of the grid connection point and the reference q-axis voltage value of the grid connection point is subjected to proportional-integral control to obtain the angular frequency correction amount of the grid-type flexible DC converter; The angular frequency of the grid connection point is obtained by superimposing the angular frequency adjustment amount, the angular frequency correction amount, and the angular frequency reference value of the grid-type flexible DC converter. The phase angle of the grid connection point is obtained by integral control of the angular frequency of the grid connection point.

4. The control method according to claim 2, characterized in that, The step of calculating the current reference value feedforward of the grid-type flexible DC converter based on the actual DC voltage value of the grid-type flexible DC converter includes: The difference between the DC voltage reference value and the actual DC voltage value of the grid-type flexible DC converter is used for proportional-integral control to obtain the current reference value feedforward.

5. The control method according to claim 2, characterized in that, The control of the grid-type flexible DC converter based on the phase angle of the grid connection point and the feedforward amount of the current reference value includes: The current reference value of the grid-type flexible DC converter is calculated based on the actual reactive power value of the grid-type flexible DC converter and the actual voltage value of the grid connection point. The modulation voltage reference value of the grid-connected flexible DC converter is calculated based on the actual voltage value of the grid connection point, the current reference value of the grid-type flexible DC converter, and the feedforward of the current reference value. Based on the phase angle of the grid connection point, the modulation voltage reference value of the grid-type flexible DC converter is subjected to an inverse Parker transform to obtain the modulation signal; The grid-type flexible DC converter is controlled according to the modulation signal.

6. The control method according to claim 5, characterized in that, The calculation of the current reference value of the grid-type flexible DC converter based on the actual reactive power value of the grid-type flexible DC converter and the actual voltage value of the grid connection point includes: The difference between the reactive power reference value and the actual reactive power value of the grid-type flexible DC converter is used for proportional-integral control to obtain the d-axis voltage correction value of the grid-type flexible DC converter. The d-axis current reference value of the grid-type flexible DC converter is then calculated based on the d-axis voltage correction value, the actual d-axis voltage value at the grid connection point, and the d-axis voltage reference value at the grid connection point. The difference between the reference value of the q-axis voltage at the grid connection point and the actual value of the q-axis voltage at the grid connection point is used for proportional-integral control to obtain the reference value of the q-axis current of the grid-type flexible DC converter in a two-phase rotating coordinate system.

7. The control method according to claim 6, characterized in that, The d-axis current reference value of the grid-type flexible DC converter satisfies: in, This represents the d-axis current reference value of the grid-type flexible DC converter. This represents the d-axis voltage correction amount of the grid-type flexible DC converter. This represents the d-axis voltage reference value at the grid connection point. This represents the actual d-axis voltage value at the grid connection point. This represents the proportionality coefficient. Represents the integral coefficient. s Represents a complex variable in the complex frequency domain.

8. The control method according to claim 5, characterized in that, The step of calculating the modulation voltage reference value of the grid-connected flexible DC converter based on the actual voltage value of the grid connection point, the current reference value of the grid-connected flexible DC converter, and the feedforward of the current reference value includes: The d-axis current deviation of the grid-type flexible DC converter is calculated based on the d-axis current reference value, the actual d-axis voltage value, and the current reference value feedforward. The difference between the q-axis current reference value and the actual q-axis current value of the grid-type flexible DC converter is taken as the q-axis current deviation of the grid-type flexible DC converter. The d-axis current deviation is subjected to proportional-integral control to obtain the first modulation voltage of the grid-type flexible DC converter on the d-axis; the q-axis current deviation is subjected to proportional-integral control to obtain the first modulation voltage of the grid-type flexible DC converter on the q-axis. Calculate the second modulation voltage of the d-axis of the grid-type flexible DC converter based on the actual value of the q-axis current of the grid-type flexible DC converter; calculate the second modulation voltage of the q-axis of the grid-type flexible DC converter based on the actual value of the d-axis current of the grid-type flexible DC converter; The reference value of the d-axis modulation voltage of the grid-type flexible DC converter is calculated based on the first modulation voltage of the d-axis, the second modulation voltage of the d-axis, and the actual value of the d-axis voltage; the reference value of the q-axis modulation voltage of the grid-type flexible DC converter is calculated based on the first modulation voltage of the q-axis, the second modulation voltage of the q-axis, and the actual value of the q-axis voltage.

9. The control method according to claim 8, characterized in that, The d-axis current deviation of the grid-type flexible DC converter satisfies: in, This represents the d-axis current deviation of the grid-type flexible DC converter. This represents the d-axis current reference value of the grid-type flexible DC converter. This represents the actual d-axis voltage value of the grid-type flexible DC converter. This represents the feedforward amount of the current reference value.

10. The control method according to claim 8, characterized in that, The d-axis modulation voltage reference value of the grid-type flexible DC converter satisfies: in, This represents the d-axis modulation voltage reference value of the grid-type flexible DC converter; This represents the actual value of the d-axis voltage of the grid-type flexible DC converter; This represents the first modulation voltage along the d-axis of the grid-type flexible DC converter; This represents the second modulation voltage along the d-axis of the grid-type flexible DC converter, satisfying... , This represents the actual value of the q-axis current of the grid-type flexible DC converter; The q-axis modulation voltage reference value of the grid-type flexible DC converter satisfies: in, This represents the reference value of the q-axis modulation voltage of the grid-type flexible DC converter; This represents the actual value of the q-axis voltage of the grid-type flexible DC converter; This represents the first modulation voltage of the q-axis of the grid-type flexible DC converter; This represents the second modulation voltage of the q-axis of the grid-type flexible DC converter, which satisfies... ω represents the angular frequency of the AC system, and L represents the equivalent inductance of the grid-type flexible DC converter. This represents the actual value of the d-axis current of the grid-type flexible DC converter.

11. A control device for a grid-type flexible DC converter, characterized in that, include: The first calculation module is used to calculate the phase angle of the grid connection point based on the actual active power value of the grid-connected flexible DC converter and the actual voltage value of the grid connection point. The second calculation module is used to calculate the current reference value feedforward of the grid-type flexible DC converter based on the actual value of the DC voltage of the grid-type flexible DC converter. The control module is used to control the grid-type flexible DC converter based on the phase angle of the grid connection point and the feedforward amount of the current reference value.

12. The control device according to claim 11, characterized in that, The control device further includes a conversion module, which is specifically used for: The actual voltage value at the grid connection point is subjected to Park transformation to obtain the actual d-axis voltage value and the actual q-axis voltage value at the grid connection point; The actual current values ​​of the grid-type flexible DC converter are subjected to Park transformation to obtain the actual d-axis current values ​​and q-axis current values ​​of the grid-type flexible DC converter.

13. The control device according to claim 12, characterized in that, The first calculation module is specifically used for: The difference between the active power reference value and the actual active power value of the grid-type flexible DC converter is used for proportional-integral control to obtain the angular frequency adjustment amount of the grid-type flexible DC converter. The difference between the actual q-axis voltage value of the grid connection point and the reference q-axis voltage value of the grid connection point is subjected to proportional-integral control to obtain the angular frequency correction amount of the grid-type flexible DC converter; The angular frequency of the grid connection point is obtained by superimposing the angular frequency adjustment amount, the angular frequency correction amount, and the angular frequency reference value of the grid-type flexible DC converter. The phase angle of the grid connection point is obtained by integral control of the angular frequency of the grid connection point.

14. The control device according to claim 12, characterized in that, The second calculation module is specifically used for: The difference between the DC voltage reference value and the actual DC voltage value of the grid-type flexible DC converter is used for proportional-integral control to obtain the current reference value feedforward.

15. The control device according to claim 12, characterized in that, The control module is specifically used for: The current reference value of the grid-type flexible DC converter is calculated based on the actual reactive power value of the grid-type flexible DC converter and the actual voltage value of the grid connection point. The modulation voltage reference value of the grid-connected flexible DC converter is calculated based on the actual voltage value of the grid connection point, the current reference value of the grid-type flexible DC converter, and the feedforward of the current reference value. Based on the phase angle of the grid connection point, the modulation voltage reference value of the grid-type flexible DC converter is subjected to an inverse Parker transform to obtain the modulation signal; The grid-type flexible DC converter is controlled according to the modulation signal.

16. The control device according to claim 15, characterized in that, The control module is specifically used for: The difference between the reactive power reference value and the actual reactive power value of the grid-type flexible DC converter is used for proportional-integral control to obtain the d-axis voltage correction value of the grid-type flexible DC converter. The d-axis current reference value of the grid-type flexible DC converter is then calculated based on the d-axis voltage correction value, the actual d-axis voltage value at the grid connection point, and the d-axis voltage reference value at the grid connection point. The difference between the reference value of the q-axis voltage at the grid connection point and the actual value of the q-axis voltage at the grid connection point is used for proportional-integral control to obtain the reference value of the q-axis current of the grid-type flexible DC converter in a two-phase rotating coordinate system.

17. The control device according to claim 16, characterized in that, The d-axis current reference value of the grid-type flexible DC converter satisfies: in, This represents the d-axis current reference value of the grid-type flexible DC converter. This represents the d-axis voltage correction amount of the grid-type flexible DC converter. This represents the d-axis voltage reference value at the grid connection point. This represents the actual d-axis voltage value at the grid connection point. This represents the proportionality coefficient. Represents the integral coefficient. s Represents a complex variable in the complex frequency domain.

18. The control device according to claim 15, characterized in that, The control module is specifically used for: The d-axis current deviation of the grid-type flexible DC converter is calculated based on the d-axis current reference value, the actual d-axis voltage value, and the current reference value feedforward. The difference between the q-axis current reference value and the actual q-axis current value of the grid-type flexible DC converter is taken as the q-axis current deviation of the grid-type flexible DC converter. The d-axis current deviation is subjected to proportional-integral control to obtain the first modulation voltage of the grid-type flexible DC converter on the d-axis; the q-axis current deviation is subjected to proportional-integral control to obtain the first modulation voltage of the grid-type flexible DC converter on the q-axis. Calculate the second modulation voltage of the d-axis of the grid-type flexible DC converter based on the actual value of the q-axis current of the grid-type flexible DC converter; calculate the second modulation voltage of the q-axis of the grid-type flexible DC converter based on the actual value of the d-axis current of the grid-type flexible DC converter; The reference value of the d-axis modulation voltage of the grid-type flexible DC converter is calculated based on the first modulation voltage of the d-axis, the second modulation voltage of the d-axis, and the actual value of the d-axis voltage; the reference value of the q-axis modulation voltage of the grid-type flexible DC converter is calculated based on the first modulation voltage of the q-axis, the second modulation voltage of the q-axis, and the actual value of the q-axis voltage.

19. The control device according to claim 18, characterized in that, The d-axis current deviation of the grid-type flexible DC converter satisfies: in, This represents the d-axis current deviation of the grid-type flexible DC converter. This represents the d-axis current reference value of the grid-type flexible DC converter. This represents the actual d-axis voltage value of the grid-type flexible DC converter. This represents the feedforward amount of the current reference value.

20. The control device according to claim 18, characterized in that, The d-axis modulation voltage reference value of the grid-type flexible DC converter satisfies: in, This represents the d-axis modulation voltage reference value of the grid-type flexible DC converter; This represents the actual value of the d-axis voltage of the grid-type flexible DC converter; This represents the first modulation voltage along the d-axis of the grid-type flexible DC converter; This represents the second modulation voltage along the d-axis of the grid-type flexible DC converter, satisfying... , This represents the actual value of the q-axis current of the grid-type flexible DC converter; The q-axis modulation voltage reference value of the grid-type flexible DC converter satisfies: in, This represents the reference value of the q-axis modulation voltage of the grid-type flexible DC converter; This represents the actual value of the q-axis voltage of the grid-type flexible DC converter; This represents the first modulation voltage of the q-axis of the grid-type flexible DC converter; This represents the second modulation voltage of the q-axis of the grid-type flexible DC converter, which satisfies... ω represents the angular frequency of the AC system, and L represents the equivalent inductance of the grid-type flexible DC converter. This represents the actual value of the d-axis current of the grid-type flexible DC converter.

21. A computer device, characterized in that, include: One or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the control method as described in any one of claims 1 to 10 is implemented.

22. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the control method as described in any one of claims 1 to 10.

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