A steady-state control method and device for a hybrid-source direct-current transformer

Abstract

This application provides a steady-state control method and apparatus for a hybrid-source DC transformer. Based on the active power reference value of the hybrid-source DC transformer, the reactive power reference value and AC voltage reference value of the voltage source converter are determined, thereby enabling control of both the current source converter and the voltage source converter. This application can flexibly control the actual active and reactive power values ​​of the voltage source converter, improving the operating efficiency of both the current source and voltage source converters, and thus improving the operating efficiency of the hybrid-source DC transformer. Furthermore, this application reduces the actual output current value of the voltage source converter by applying active power supplementary control to the actual active power value, thereby improving the operating efficiency of the voltage source converter.

Description

Technical Field

[0001] This application relates to the field of DC power transmission technology, specifically to a steady-state control method and apparatus for a hybrid-source DC transformer. Background Technology

[0002] Compared to AC transmission technology, DC transmission technology has advantages such as longer transmission distance, higher efficiency, and larger capacity. Flexible DC transmission systems, with voltage source converters (VSCs) at their core, offer advantages in flexibility, controllability, and adaptability to weak grids, playing a crucial role in renewable energy grid connection and transmission scenarios. Therefore, it is necessary to implement steady-state control of the VSC to ensure the normal operation of the flexible DC transmission system.

[0003] Related technologies typically employ dual closed-loop control of the actual output voltage and current values ​​of the VSC to obtain control signals. These signals are then used to achieve steady-state control of the VSC, thereby controlling the DC transformer. However, these technologies only control the actual output voltage and current values ​​of the VSC, resulting in poor flexibility in controlling the actual active power value. This reduces the operating efficiency of the VSC and consequently, the operating efficiency of the DC transformer. Summary of the Invention

[0004] To address the problem of low operating efficiency of DC transformers in the prior art, this application provides a steady-state control method and apparatus for a hybrid-source DC transformer.

[0005] Firstly, this application provides a steady-state control method for a hybrid-source DC transformer. The hybrid-source DC transformer includes a voltage source converter (VSC) and a current source converter (CSC) connected in parallel. The steady-state control method may include:

[0006] The reactive power reference value and AC voltage reference value of the voltage source converter are determined based on the active power reference value of the hybrid source DC transformer.

[0007] The current source converter is controlled based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer.

[0008] The voltage source converter is controlled based on the AC voltage reference value and active power reference value of the voltage source converter.

[0009] In some possible implementations, the reactive power reference value and AC voltage reference value of the voltage source converter are determined based on the active power reference value of the hybrid-source DC transformer, including:

[0010] Based on the active power reference value of the hybrid source DC transformer, the actual reactive power value of the voltage source converter is droop-controlled to obtain the reactive power reference value of the voltage source converter.

[0011] Based on the active power reference value of the hybrid source DC transformer, the actual output voltage value of the voltage source converter is droop-controlled to obtain the AC voltage reference value of the voltage source converter.

[0012] Optionally, the reactive power reference value and the AC voltage reference value of the voltage source converter shall satisfy the following:

[0013] Q VSC_ref =k PQ P ref +con PQ

[0014] u Md_ref =k PV P ref +con PV

[0015] Among them, Q VSC_ref u represents the reactive power reference value of a voltage source converter. Md_ref P represents the AC voltage reference value for a voltage source converter. ref This represents the reference value for active power of a hybrid-source DC transformer. k PQ This represents the active-reactive droop control coefficient, which satisfies... con PQ This represents the active-reactive droop control correction amount, satisfying con PQ =Q VSC_min -k PQ P ref_min k PV This represents the active power-voltage droop control coefficient, which satisfies... con PV This represents the active-voltage droop control correction amount, satisfying con PV =u Md_min -k PV P ref_min Q VSC_max Q represents the maximum reactive power of a voltage source converter. VSC_min This represents the minimum reactive power of a voltage source converter. Md_max u represents the maximum AC voltage of a voltage source converter. Md_min This represents the minimum AC voltage of a voltage source converter. P ref_max P represents the maximum active power of a hybrid-source DC transformer. ref_minThis represents the minimum active power of a hybrid-source DC transformer.

[0016] In other possible implementations, the current source converter is controlled based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer, including:

[0017] Based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer, the actual DC voltage value of the hybrid source DC transformer and the actual output current value of the current source converter are subjected to voltage and current dual closed-loop control to obtain the output current modulation amount of the current source converter.

[0018] Calculate the phase shift angle and bridge arm straight-through angle of the current source converter based on the output current modulation of the current source converter.

[0019] Based on the voltage value of the filter capacitor in the current source converter, the phase shift angle and bridge arm through-angle of the current source converter are modulated by a dual-degree-of-freedom fundamental frequency, and the first modulation signal is output to the current source converter.

[0020] Furthermore, based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer, a dual closed-loop voltage-current control is performed on the actual DC voltage value of the hybrid source DC transformer and the actual output current value of the current source converter to obtain the output current modulation amount of the current source converter, including:

[0021] The difference between the DC voltage reference value and the actual DC voltage value of the hybrid-source DC transformer is used for proportional-integral control to obtain the d-axis component of the output current reference value of the current-source converter. Similarly, the difference between the reactive power reference value and the actual reactive power value of the voltage-source converter is used for proportional-integral control to obtain the q-axis component of the output current reference value of the current-source converter.

[0022] By performing a Parker transformation on the actual output current value of the current source converter, the d-axis and q-axis components of the actual output current value of the current source converter are obtained.

[0023] The d-axis modulation of the current source converter's output current is obtained by applying proportional-integral (PI) control to the difference between the d-axis component of the current source converter's output current reference value and the actual d-axis component of the current source converter's output current. Similarly, the q-axis modulation of the current source converter's output current is obtained by applying PPI control to the difference between the q-axis component of the current source converter's output current reference value and the actual q-axis component of the current source converter's output current.

[0024] Optionally, the phase shift angle and arm straight-through angle of the current source converter shall satisfy:

[0025]

[0026] Where α represents the phase shift angle of the current source converter, θ represents the arm straight-through angle of the current source converter, and i fd_con i represents the d-axis component of the output current modulation of a current source converter. fq_con i represents the q-axis component of the output current modulation of a current source converter. L This represents the actual value of the DC current in the hybrid DC converter.

[0027] In some other possible implementations, the voltage source converter is controlled based on the AC voltage reference value and active power reference value, including:

[0028] The actual active power of the voltage source converter is calculated based on the actual output current and actual output voltage of the voltage source converter. The difference between the reference active power value and the actual active power value of the voltage source converter is then subjected to proportional-integral control to obtain the AC voltage correction amount of the voltage source converter.

[0029] Based on the AC voltage correction value and AC voltage reference value of the voltage source converter, the actual output current value and the actual output voltage value of the voltage source converter are controlled by a dual closed-loop voltage and current control to obtain the output current control signal of the voltage source converter.

[0030] The output current control signal of the voltage source converter is subjected to inverse Parker transformation and modulation, and a second modulation signal is output to the voltage source converter.

[0031] Optionally, based on the AC voltage correction value and AC voltage reference value of the voltage source converter, a dual closed-loop control of voltage and current is performed on the actual values ​​of the output current and output voltage of the voltage source converter to obtain the output current control signal of the voltage source converter, including:

[0032] A Parker transform is applied to the actual output current value of the voltage source converter to obtain the d-axis and q-axis components of the actual output current value. Similarly, a Parker transform is applied to the actual output voltage value of the voltage source converter to obtain its d-axis and q-axis components.

[0033] The d-axis component of the modulation voltage of the voltage source converter is calculated based on the d-axis component of the actual output voltage and the AC voltage correction. Proportional-integral (PI) control is then applied to the d-axis component of the modulation voltage to obtain the d-axis component of the voltage source converter's output current reference value. The difference between the q-axis component of the AC voltage reference value and the q-axis component of the actual output voltage is then applied to obtain the q-axis component of the voltage source converter's output current reference value.

[0034] The difference between the d-axis component of the voltage source converter output current reference value and the d-axis component of the actual voltage source converter output current is used for proportional-integral control to obtain the d-axis component of the voltage source converter modulation current. Similarly, the difference between the q-axis component of the voltage source converter output current reference value and the q-axis component of the actual voltage source converter output current is used for proportional-integral control to obtain the q-axis component of the voltage source converter modulation current.

[0035] The d-axis component of the output current control signal of the voltage source converter is calculated based on the d-axis component of the modulation current of the voltage source converter, and the q-axis component of the output current control signal of the voltage source converter is calculated based on the q-axis component of the modulation current of the voltage source converter.

[0036] For example, the d-axis component of the modulation voltage of a voltage source converter satisfies:

[0037] u Md_con =Δu Md +u Md_ref -u Md

[0038] Among them, u Md_con The modulated voltage d-axis component, Δu, represents the voltage source converter. Md u represents the AC voltage correction value of a voltage source converter. Md_ref The d-axis component of the AC voltage reference value of the voltage source converter, u Md The d-axis component represents the actual output voltage value of a voltage source converter.

[0039] Optionally, the d-axis and q-axis components of the output current control signal of the voltage source converter satisfy:

[0040] i Md_con =u Md +i Md1 -ωLi Md

[0041] i Mq_con =u Mq +i Mq1 +ωLi Mq

[0042] Among them, i Md_con The d-axis component of the output current control signal of a voltage source converter, u Md i represents the d-axis component of the actual output voltage of a voltage source converter. Md1 i represents the d-axis component of the modulation current of a voltage source converter. Md The d-axis component represents the actual value of the output current of a voltage source converter. Mq_conu represents the q-axis component of the output current control signal of a voltage source converter. Mq i represents the q-axis component of the actual output voltage of a voltage source converter. Mq1 i represents the q-axis component of the modulation current of a voltage source converter. Mq This represents the q-axis component of the actual output current of the voltage source converter. ω represents the angular frequency of the voltage source converter, and L represents the inductance of the bridge arm inductor in the voltage source converter.

[0043] Secondly, this application provides a steady-state control device for a hybrid-source DC transformer. The hybrid-source DC transformer includes a voltage source converter and a current source converter connected in parallel. The steady-state control device may include:

[0044] The determination module is used to determine the reactive power reference value and AC voltage reference value of the voltage source converter based on the active power reference value of the hybrid source DC transformer.

[0045] The first control module is used to control the current source converter based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer.

[0046] The second control module is used to control the voltage source converter based on the AC voltage reference value and active power reference value of the voltage source converter.

[0047] In some possible implementations, the module is specifically used for:

[0048] Based on the active power reference value of the hybrid source DC transformer, the actual reactive power value of the voltage source converter is droop-controlled to obtain the reactive power reference value of the voltage source converter.

[0049] Based on the active power reference value of the hybrid source DC transformer, the actual output voltage value of the voltage source converter is droop-controlled to obtain the AC voltage reference value of the voltage source converter.

[0050] Optionally, the reactive power reference value and the AC voltage reference value of the voltage source converter shall satisfy the following:

[0051] Q VSC_ref =k PQ P ref +con PQ

[0052] u Md_ref =k PV P ref +con PV

[0053] Among them, Q VSC_refu represents the reactive power reference value of a voltage source converter. Md_ref P represents the AC voltage reference value for a voltage source converter. ref This represents the reference value for active power of a hybrid-source DC transformer. k PQ This represents the active-reactive droop control coefficient, which satisfies... con PQ This represents the active-reactive droop control correction amount, satisfying con PQ =Q VSC_min -k PQ P ref_min k PV This represents the active power-voltage droop control coefficient, which satisfies... con PV This represents the active-voltage droop control correction amount, satisfying con PV =u Md_min -k PV P ref_min Q VSC_max Q represents the maximum reactive power of a voltage source converter. VSC_min This represents the minimum reactive power of a voltage source converter. Md_max u represents the maximum AC voltage of a voltage source converter. Md_min This represents the minimum AC voltage of a voltage source converter. P ref_max P represents the maximum active power of a hybrid-source DC transformer. ref_min This represents the minimum active power of a hybrid-source DC transformer.

[0054] In some other possible implementations, the first control module is specifically used for:

[0055] Based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer, the actual DC voltage value of the hybrid source DC transformer and the actual output current value of the current source converter are subjected to voltage and current dual closed-loop control to obtain the output current modulation amount of the current source converter.

[0056] Calculate the phase shift angle and bridge arm straight-through angle of the current source converter based on the output current modulation of the current source converter.

[0057] Based on the voltage value of the filter capacitor in the current source converter, the phase shift angle and bridge arm through-angle of the current source converter are modulated by a dual-degree-of-freedom fundamental frequency, and the first modulation signal is output to the current source converter.

[0058] Optionally, the first control module is specifically used for:

[0059] The difference between the DC voltage reference value and the actual DC voltage value of the hybrid-source DC transformer is used for proportional-integral control to obtain the d-axis component of the output current reference value of the current-source converter. Similarly, the difference between the reactive power reference value and the actual reactive power value of the voltage-source converter is used for proportional-integral control to obtain the q-axis component of the output current reference value of the current-source converter.

[0060] By performing a Parker transformation on the actual output current value of the current source converter, the d-axis and q-axis components of the actual output current value of the current source converter are obtained.

[0061] The d-axis modulation of the current source converter's output current is obtained by applying proportional-integral (PI) control to the difference between the d-axis component of the current source converter's output current reference value and the actual d-axis component of the current source converter's output current. Similarly, the q-axis modulation of the current source converter's output current is obtained by applying PPI control to the difference between the q-axis component of the current source converter's output current reference value and the actual q-axis component of the current source converter's output current.

[0062] The phase shift angle and arm straight-through angle of the current source converter satisfy:

[0063]

[0064] Where α represents the phase shift angle of the current source converter, θ represents the arm straight-through angle of the current source converter, and i fd_con i represents the d-axis component of the output current modulation of a current source converter. fq_con i represents the q-axis component of the output current modulation of a current source converter. L This represents the actual value of the DC current in the hybrid DC converter.

[0065] In some other possible implementations, the second control module is specifically used for:

[0066] The actual active power of the voltage source converter is calculated based on the actual output current and actual output voltage of the voltage source converter. The difference between the reference active power value and the actual active power value of the voltage source converter is then subjected to proportional-integral control to obtain the AC voltage correction amount of the voltage source converter.

[0067] Based on the AC voltage correction value and AC voltage reference value of the voltage source converter, the actual output current value and the actual output voltage value of the voltage source converter are controlled by a dual closed-loop voltage and current control to obtain the output current control signal of the voltage source converter.

[0068] The output current control signal of the voltage source converter is subjected to inverse Parker transformation and modulation, and a second modulation signal is output to the voltage source converter.

[0069] Optionally, the second control module is specifically used for:

[0070] A Parker transform is applied to the actual output current value of the voltage source converter to obtain the d-axis and q-axis components of the actual output current value. Similarly, a Parker transform is applied to the actual output voltage value of the voltage source converter to obtain its d-axis and q-axis components.

[0071] The d-axis component of the modulation voltage of the voltage source converter is calculated based on the d-axis component of the actual output voltage and the AC voltage correction. Proportional-integral (PI) control is then applied to the d-axis component of the modulation voltage to obtain the d-axis component of the voltage source converter's output current reference value. The difference between the q-axis component of the AC voltage reference value and the q-axis component of the actual output voltage is then applied to obtain the q-axis component of the voltage source converter's output current reference value.

[0072] The difference between the d-axis component of the voltage source converter output current reference value and the d-axis component of the actual voltage source converter output current is used for proportional-integral control to obtain the d-axis component of the voltage source converter modulation current. Similarly, the difference between the q-axis component of the voltage source converter output current reference value and the q-axis component of the actual voltage source converter output current is used for proportional-integral control to obtain the q-axis component of the voltage source converter modulation current.

[0073] The d-axis component of the output current control signal of the voltage source converter is calculated based on the d-axis component of the modulation current of the voltage source converter, and the q-axis component of the output current control signal of the voltage source converter is calculated based on the q-axis component of the modulation current of the voltage source converter.

[0074] For example, the d-axis component of the modulation voltage of a voltage source converter satisfies:

[0075] u Md_con =Δu Md +u Md _ ref -u Md

[0076] Among them, u Md_con The modulated voltage d-axis component, Δu, represents the voltage source converter. Md u represents the AC voltage correction value of a voltage source converter. Md_ref The d-axis component of the AC voltage reference value of the voltage source converter, u Md The d-axis component represents the actual output voltage value of a voltage source converter.

[0077] The d-axis and q-axis components of the output current control signal of a voltage source converter satisfy the following:

[0078] i Md_con =u Md +i Md1 -ωLi Md

[0079] i Mq_con =u Mq +i Mq1 +ωLi Mq

[0080] Among them, i Md_con The d-axis component of the output current control signal of a voltage source converter, u Md i represents the d-axis component of the actual output voltage of a voltage source converter. Md1 i represents the d-axis component of the modulation current of a voltage source converter. Md The d-axis component represents the actual value of the output current of a voltage source converter. Mq_con u represents the q-axis component of the output current control signal of a voltage source converter. Mq i represents the q-axis component of the actual output voltage of a voltage source converter. Mq1 i represents the q-axis component of the modulation current of a voltage source converter. Mq This represents the q-axis component of the actual output current of the voltage source converter. ω represents the angular frequency of the voltage source converter, and L represents the inductance of the bridge arm inductor in the voltage source converter.

[0081] In another aspect, this application also provides a computer device, including: one or more processors.

[0082] A processor is used to execute one or more programs.

[0083] When one or more programs are executed by one or more processors, the steady-state control method described above is implemented.

[0084] 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 steady-state control method described above.

[0085] Compared with the prior art, the beneficial effects of this application are as follows:

[0086] The steady-state control method for a hybrid-source DC transformer provided in this application determines the reactive power reference value and AC voltage reference value of the voltage source converter based on the active power reference value of the hybrid-source DC transformer. Then, the current source converter is controlled using the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid-source DC transformer, and the voltage source converter is controlled using the AC voltage reference value and active power reference value of the voltage source converter. It can be seen that the reactive power reference value and AC voltage reference value of the voltage source converter are determined based on the active power reference value of the hybrid-source DC transformer, rather than being pre-set reference values. This allows for flexible control of the actual active and reactive power values ​​of the voltage source converter, improving the operating efficiency of both the current source and voltage source converters, and consequently improving the operating efficiency of the hybrid-source DC transformer.

[0087] This application achieves AC voltage correction by performing active power additional control on the actual active power value of the voltage source converter. This allows for timely and automatic adjustment of the AC voltage of the voltage source converter based on the AC voltage correction value when the actual active power value of the voltage source converter varies, thereby reducing the actual output current value of the voltage source converter and improving its operating efficiency.

[0088] This application uses the active power reference value of the hybrid-source DC transformer to perform droop control on the actual reactive power value of the voltage source converter to obtain the reactive power reference value of the voltage source converter. It also uses the active power reference value of the hybrid-source DC transformer to perform droop control on the actual output voltage value of the voltage source converter to obtain the AC voltage reference value of the voltage source converter. When the actual active power value of the voltage source converter differs, the application automatically adjusts the reactive power reference value and the AC voltage reference value of the voltage source converter. This achieves stable control of the current source converter to maintain the actual DC voltage value and stable output of the voltage source converter to maintain the actual reactive power value, thereby achieving stable operation of the entire hybrid-source DC transformer. Attached Figure Description

[0089] 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.

[0090] Figure 1 This is a schematic structural diagram of a hybrid-source DC transformer in an embodiment of this application;

[0091] Figure 2 This is a schematic flowchart of a steady-state control method for a hybrid-source DC transformer in an embodiment of this application;

[0092] Figure 3 This is another schematic flowchart of the steady-state control method for a hybrid-source DC transformer in the embodiments of this application;

[0093] Figure 4 This is a schematic flowchart illustrating the determination of reactive power reference values ​​and AC voltage reference values ​​for a voltage source converter in an embodiment of this application.

[0094] Figure 5 This is a schematic flowchart illustrating the control of a current source converter in an embodiment of this application;

[0095] Figure 6 This is a schematic flowchart illustrating the control of a voltage source converter in an embodiment of this application;

[0096] Figure 7 This is a schematic structural diagram of a steady-state control device for a hybrid-source DC transformer in an embodiment of this application. Detailed Implementation

[0097] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0098] 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.

[0099] 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.

[0100] Example 1:

[0101] This application provides a steady-state control method for a hybrid-source DC transformer. For example... Figure 1 As shown, the hybrid source DC transformer 100 may include a current source converter (CSC), a voltage source converter (VSC), a transformer module T, and a diode rectifier unit (DRU). dc L represents DC inductance. f C represents the filter capacitor. f This represents the filter capacitor. After CSC and VSC are connected in parallel, the current flows through L... f and C f Transformer module T is connected, and transformer module T is also connected to DRU.

[0102] like Figure 2 and Figure 3 As shown, the steady-state control method 200 may include the following steps:

[0103] Step S1: Based on the active power reference value P of the hybrid source DC transformer ref Determine the reactive power reference value Q for the voltage source converter. VSC_ref and AC voltage reference value u Md_ref .

[0104] Step S2: Based on the reactive power reference value Q of the voltage source converter VSC_ref DC voltage reference value u of hybrid source DC transformer dc_L_ref Control the current source converter.

[0105] Step S3: Based on the AC voltage reference value u of the voltage source converter Md_refand active power reference value P VSC_ref Control the voltage source converter.

[0106] In some possible implementations, determining the reactive power reference value and AC voltage reference value of the voltage source converter based on the active power reference value of the hybrid-source DC transformer in step S1 includes:

[0107] like Figure 3 and Figure 4 As shown, based on the active power reference value P of the hybrid source DC transformer... ref By performing droop control on the actual reactive power value of the voltage source converter, a reference reactive power value Q of the voltage source converter can be obtained. VSC_ref .

[0108] Based on the active power reference value P of the hybrid-source DC transformer ref By performing droop control on the actual output voltage value of the voltage source converter, the AC voltage reference value u of the voltage source converter can be obtained. Md_ref .

[0109] Optionally, the reactive power reference value and the AC voltage reference value of the voltage source converter shall satisfy the following:

[0110] Q VSC_ref =k PQ P ref +con PQ

[0111] u Md_ref =k PV P ref +con PV

[0112] Among them, Q VSC_ref u represents the reactive power reference value of a voltage source converter. Md_ref P represents the AC voltage reference value for a voltage source converter. ref This represents the reference value for active power of a hybrid-source DC transformer. k PQ This represents the active-reactive droop control coefficient, which satisfies... con PQ This represents the active-reactive droop control correction amount, satisfying con PQ =Q VSC_min -k PQ P ref_min k PV This represents the active power-voltage droop control coefficient, which satisfies... con PV This represents the active-voltage droop control correction amount, satisfying con PV =u Md_min -kPV P ref_min Q VSC_max Q represents the maximum reactive power of a voltage source converter. VSC_min This represents the minimum reactive power of a voltage source converter. Md_max u represents the maximum AC voltage of a voltage source converter. Md_min This represents the minimum AC voltage of a voltage source converter. P ref_max P represents the maximum active power of a hybrid-source DC transformer. ref_min This represents the minimum active power of a hybrid-source DC transformer.

[0113] In some other possible implementations, step S2 above, based on the reactive power reference value Q of the voltage source converter, VSC_ref DC voltage reference value u of hybrid source DC transformer Md_ref Controlling the current source converter's control circuit (CSC) includes:

[0114] like Figure 3 and Figure 5 As shown, based on the reactive power reference value Q of the voltage source converter... VSC_ref DC voltage reference value u of hybrid source DC transformer dc_L_ref The actual DC voltage value u of a hybrid source DC transformer dc_L The actual output current value of the current source converter (i.e., the d-axis component i of the actual output current value of the current source converter) fd and q-axis component i fq Voltage and current dual closed-loop control is performed to obtain the output current modulation of the current source converter CSC (i.e., the d-axis component i of the output current modulation of the current source converter). fd_con The q-axis component i of the output current modulation of a current source converter fq_con ). Figure 3 In the middle, L dc This indicates a DC inductor, and T indicates a transformer module.

[0115] According to the output current modulation amount (i) of the current source converter fd_con and i fq_con Calculate the phase shift angle α and the arm straight-through angle θ of the current source converter (CSC).

[0116] Based on the voltage value u of the filter capacitor in the current source converter C By performing dual-degree-of-freedom fundamental frequency modulation on the phase shift angle α and the bridge arm through-angle θ of the current source converter CSC, and outputting the first modulation signal S1 to the current source converter CSC, the control of the CSC can be realized.

[0117] Furthermore, according to the reactive power reference value Q of the voltage source converter...VSC_ref DC voltage reference value u of hybrid source DC transformer dc_L_ref The actual DC voltage value u of a hybrid source DC transformer dc_L The actual output current value of the current source converter is used for voltage and current dual closed-loop control (i.e., voltage outer loop control and current inner loop control) to obtain the output current modulation amount of the current source converter CSC, including:

[0118] refer to Figure 5 The DC voltage reference value u of the hybrid source DC transformer dc_L_ref Compared with the actual value of DC voltage u dc_L The difference is used for proportional-integral control (i.e., PI control) to obtain the d-axis component i of the current source converter output current reference value. fd_ref The reactive power reference value Q of the voltage source converter. VSC_ref With the actual value of reactive power Q VSC The difference is used for proportional-integral control to obtain the q-axis component i of the current source converter output current reference value. fq_ref .

[0119] The actual value of the output current i of the current source converter f Perform a Parker transform to obtain the d-axis component i of the actual output current of the current source converter. fd and q-axis component i fq .

[0120] The d-axis component i of the output current reference value of the current source converter fd_ref The d-axis component i of the actual output current of the current source converter fd The difference is used for proportional-integral control to obtain the d-axis modulation amount i of the current source converter output current. fd_con The q-axis component i of the output current reference value of the current source converter. fq_ref The q-axis component i of the actual output current of the current source converter fq The difference is used for proportional-integral control to obtain the q-axis modulation amount i of the current source converter output current. fq_con .

[0121] Optionally, the phase shift angle and arm straight-through angle of the current source converter shall satisfy:

[0122]

[0123] Where α represents the phase shift angle of the current source converter, θ represents the arm straight-through angle of the current source converter, and i fd_con i represents the d-axis component of the output current modulation of a current source converter. fq_con i represents the q-axis component of the output current modulation of a current source converter. LThis represents the actual value of the DC current in the hybrid DC converter.

[0124] In some other possible implementations, step S3 involves using the AC voltage reference value u from the voltage source converter. Md_ref and active power reference value P VSC_ref Controlling the voltage source converter (VSC) includes:

[0125] like Figure 6 As shown, based on the actual value i of the output current of the voltage source converter... M and the actual value of the output voltage u M Calculate the actual active power P of the voltage source converter. VSC And the active power reference value P of the voltage source converter. VSC_ref (Can be taken as 0) and the actual value of active power P VSC The difference is used for proportional-integral control to obtain the AC voltage correction Δu of the voltage source converter. Md In other words, the actual active power P of the voltage source converter can be obtained. VSC By performing active power supplementary control, the AC voltage correction Δu of the voltage source converter is obtained. Md .

[0126] refer to Figure 3 and Figure 6 Based on the AC voltage correction Δu of the voltage source converter Md and the d-axis component u of the AC voltage reference value (i.e., the AC voltage reference value of the voltage source converter). Md_ref The actual output current value of the voltage source converter (including the d-axis component i of the actual output current value of the voltage source converter) Md and q-axis component i Mq ) and the actual output voltage value (including the d-axis component u of the actual output voltage value of the voltage source converter) Md and q-axis component u Mq The voltage and current dual closed-loop control (including voltage outer loop control and current inner loop control) is performed to obtain the output current control signal of the voltage source converter (including the d-axis component i of the output current control signal of the voltage source converter). Md_con and q-axis component i Mq_con ).

[0127] The output current control signal of the voltage source converter is subjected to inverse Parker transformation and modulation, and the second modulation signal S2 is output to the voltage source converter VSC to realize the control of VSC.

[0128] Optionally, based on the AC voltage correction Δu of the voltage source converter. MdUsing the AC voltage reference value, a dual closed-loop voltage-current control is performed on the actual output current and actual output voltage values ​​of the voltage source converter to obtain the output current control signal of the voltage source converter, including:

[0129] The actual value of the output current i of the voltage source converter M Perform a Parker transform to obtain the d-axis component i of the actual output current of the voltage source converter. Md and q-axis component i Mq The actual output voltage u of the voltage source converter. M Perform a Parker transform to obtain the d-axis component u of the actual output voltage of the voltage source converter. Md and q-axis component u Mq .

[0130] like Figure 6 As shown, the d-axis component u of the actual output voltage of the voltage source converter is... Md AC voltage correction Δu Md Calculate the d-axis component u of the modulation voltage of a voltage source converter. Md_con And the modulation voltage d-axis component u of the voltage source converter Md_con Proportional-integral control is performed to obtain the d-axis component i of the voltage source converter output current reference value. Md_ref The q-axis component u of the AC voltage reference value for a voltage source converter. Mq_ref (can be set to 0) and the q-axis component u of the actual output voltage of the voltage source converter. Mq The difference is used for proportional-integral control to obtain the q-axis component i of the voltage source converter output current reference value. Mq_ref The d-axis component of the modulation voltage of the voltage source converter satisfies:

[0131] u Md_con =Δu Md +u Md _ ref -u Md

[0132] Among them, u Mq_con The modulated voltage d-axis component, Δu, represents the voltage source converter. Md u represents the AC voltage correction value of a voltage source converter. Md_ref The d-axis component of the AC voltage reference value of the voltage source converter, u Md The d-axis component represents the actual output voltage value of a voltage source converter.

[0133] The d-axis component i of the voltage source converter output current reference value Md_ref The d-axis component i of the actual output current of the voltage source converter MdThe difference is used for proportional-integral control to obtain the d-axis component i of the modulation current of the voltage source converter. Md1 The q-axis component i of the voltage source converter output current reference value. Mq_ref The q-axis component i of the actual output current of the voltage source converter Mq The difference is used for proportional-integral control to obtain the q-axis component i of the modulation current of the voltage source converter. Mq1 .

[0134] Based on the d-axis component i of the modulation current of the voltage source converter Md1 Calculate the d-axis component i of the output current control signal of the voltage source converter. Md_con According to the q-axis component i of the modulation current of the voltage source converter Mq1 Calculate the q-axis component i of the output current control signal of the voltage source converter. Mq_con .

[0135] Optionally, the d-axis and q-axis components of the output current control signal of the voltage source converter satisfy:

[0136] i Md_con =u Md +i Md1 -ωLi Md

[0137] i Mq_con =u Mq +i Mq1 +ωLi Mq

[0138] Among them, i Md_con The d-axis component of the output current control signal of a voltage source converter, u Md i represents the d-axis component of the actual output voltage of a voltage source converter. Md1 i represents the d-axis component of the modulation current of a voltage source converter. Md The d-axis component represents the actual value of the output current of a voltage source converter. Mq_con u represents the q-axis component of the output current control signal of a voltage source converter. Mq i represents the q-axis component of the actual output voltage of a voltage source converter. Mq1 i represents the q-axis component of the modulation current of a voltage source converter. Mq This represents the q-axis component of the actual output current of the voltage source converter. ω represents the angular frequency of the voltage source converter, and L represents the inductance of the bridge arm inductor in the voltage source converter.

[0139] Example 2:

[0140] Based on the same inventive concept, the embodiment also provides a steady-state control device for a hybrid-source DC transformer. The hybrid-source DC transformer can be referenced from... Figure 1 As described above, the embodiments of this application will not be repeated. Figure 7 As shown, the steady-state control device 300 includes:

[0141] Module 301 is used to determine the active power reference value P of the hybrid-source DC transformer. ref Determine the reactive power reference value Q for the voltage source converter. VSC_ref and AC voltage reference value u Md_ref .

[0142] The first control module 301 is used to determine the reactive power reference value Q of the voltage source converter. VSC_ref DC voltage reference value u of hybrid source DC transformer dc_L_ref Control the current source converter.

[0143] The second control module 303 is used to determine the AC voltage reference value u of the voltage source converter. Md_ref and active power reference value P VSC_ref Control the voltage source converter.

[0144] In some possible implementations, the determination module 301 is specifically used for:

[0145] like Figure 3 and Figure 4 As shown, based on the active power reference value P of the hybrid source DC transformer... ref By performing droop control on the actual reactive power value of the voltage source converter, a reference reactive power value Q of the voltage source converter can be obtained. VSC_ref .

[0146] Based on the active power reference value P of the hybrid-source DC transformer ref By performing droop control on the actual output voltage value of the voltage source converter, the AC voltage reference value u of the voltage source converter can be obtained. Md_ref .

[0147] Optionally, the reactive power reference value and the AC voltage reference value of the voltage source converter shall satisfy the following:

[0148] Q VSC_ref =k PQ P ref +con PQ

[0149] u Md_ref =k PV P ref +con PV

[0150] Among them, Q VSC_ref u represents the reactive power reference value of a voltage source converter. Md_ref P represents the AC voltage reference value for a voltage source converter. ref This represents the reference value for active power of a hybrid-source DC transformer. k PQ This represents the active-reactive droop control coefficient, which satisfies... con PQ This represents the active-reactive droop control correction amount, satisfying con PQ =Q VSC_min -k PQ P ref_min k PV This represents the active power-voltage droop control coefficient, which satisfies... con PV This represents the active-voltage droop control correction amount, satisfying con PV =u Md_min -k PV P ref_min Q VSC_max Q represents the maximum reactive power of a voltage source converter. VSC_min This represents the minimum reactive power of a voltage source converter. Md_max u represents the maximum AC voltage of a voltage source converter. Md_min This represents the minimum AC voltage of a voltage source converter. P ref_max P represents the maximum active power of a hybrid-source DC transformer. ref_min This represents the minimum active power of a hybrid-source DC transformer.

[0151] In some other possible implementations, the first control module 302 is specifically used for:

[0152] like Figure 3 and Figure 5 As shown, based on the reactive power reference value Q of the voltage source converter... VSC_ref DC voltage reference value u of hybrid source DC transformer dc_L_ref The actual DC voltage value u of a hybrid source DC transformer dc_L The actual output current value of the current source converter (i.e., the d-axis component i of the actual output current value of the current source converter) fd and q-axis component i fq Voltage and current dual closed-loop control is performed to obtain the output current modulation of the current source converter CSC (i.e., the d-axis component i of the output current modulation of the current source converter). fd_con The q-axis component i of the output current modulation of a current source converter fq_con ).

[0153] According to the output current modulation amount (i) of the current source converter fd_con and i fq_con Calculate the phase shift angle α and the arm straight-through angle θ of the current source converter (CSC).

[0154] Based on the voltage value u of the filter capacitor in the current source converter C By performing dual-degree-of-freedom fundamental frequency modulation on the phase shift angle α and the bridge arm through-angle θ of the current source converter CSC, and outputting the first modulation signal S1 to the current source converter CSC, the control of the CSC can be realized.

[0155] Optionally, the first control module 302 is specifically used for:

[0156] refer to Figure 5 The DC voltage reference value u of the hybrid source DC transformer dc_L_ref Compared with the actual value of DC voltage u dc_L The difference is used for proportional-integral control (i.e., PI control) to obtain the d-axis component i of the current source converter output current reference value. fd_ref The reactive power reference value Q of the voltage source converter. VSC_ref With the actual value of reactive power Q VSC The difference is used for proportional-integral control to obtain the q-axis component i of the current source converter output current reference value. fq_ref .

[0157] The actual value of the output current i of the current source converter f Perform a Parker transform to obtain the d-axis component i of the actual output current of the current source converter. fd and q-axis component i fq .

[0158] The d-axis component i of the output current reference value of the current source converter fd_ref The d-axis component i of the actual output current of the current source converter fd The difference is used for proportional-integral control to obtain the d-axis modulation amount i of the current source converter output current. fd_con The q-axis component i of the output current reference value of the current source converter. fq_ref The q-axis component i of the actual output current of the current source converter fq The difference is used for proportional-integral control to obtain the q-axis modulation amount i of the current source converter output current. fq_con .

[0159] The phase shift angle and arm straight-through angle of the current source converter satisfy:

[0160]

[0161] Where α represents the phase shift angle of the current source converter, θ represents the arm straight-through angle of the current source converter, and i fd_con i represents the d-axis component of the output current modulation of a current source converter. fq_con i represents the q-axis component of the output current modulation of a current source converter. L This represents the actual value of the DC current in the hybrid DC converter.

[0162] In some other possible implementations, the second control module 303 is specifically used for:

[0163] like Figure 6 As shown, based on the actual value i of the output current of the voltage source converter... M and the actual value of the output voltage u M Calculate the actual active power P of the voltage source converter. VSC And the active power reference value P of the voltage source converter. VSC_ref (Can be taken as 0) and the actual value of active power P VSC The difference is used for proportional-integral control to obtain the AC voltage correction Δu of the voltage source converter. Md .

[0164] refer to Figure 3 and Figure 6 Based on the AC voltage correction Δu of the voltage source converter Md and the d-axis component u of the AC voltage reference value (i.e., the AC voltage reference value of the voltage source converter). Md_ref The actual output current value of the voltage source converter (including the d-axis component i of the actual output current value of the voltage source converter) Md and q-axis component i Mq ) and the actual output voltage value (including the d-axis component u of the actual output voltage value of the voltage source converter) Md and q-axis component u Mq This involves performing dual closed-loop control of voltage and current to obtain the output current control signal of the voltage source converter (including the d-axis component i of the output current control signal of the voltage source converter). Md_con and q-axis component i Mq_con ).

[0165] The output current control signal of the voltage source converter is subjected to inverse Parker transformation and modulation, and the second modulation signal S2 is output to the voltage source converter VSC to realize the control of VSC.

[0166] Optionally, the second control module 303 is specifically used for:

[0167] The actual value of the output current i of the voltage source converter M Perform a Parker transform to obtain the d-axis component i of the actual output current of the voltage source converter.Md and q-axis component i Mq The actual output voltage u of the voltage source converter. M Perform a Parker transform to obtain the d-axis component u of the actual output voltage of the voltage source converter. Md and q-axis component u Mq .

[0168] like Figure 6 As shown, the d-axis component u of the actual output voltage of the voltage source converter is... Md AC voltage correction Δu Md Calculate the d-axis component u of the modulation voltage of a voltage source converter. Md_con And the modulation voltage d-axis component u of the voltage source converter Md_con Proportional-integral control is performed to obtain the d-axis component i of the voltage source converter output current reference value. Md_ref The q-axis component u of the AC voltage reference value for a voltage source converter. Mq_ref (can be set to 0) and the q-axis component u of the actual output voltage of the voltage source converter. Mq The difference is used for proportional-integral control to obtain the q-axis component i of the voltage source converter output current reference value. Mq_ref The d-axis component of the modulation voltage of the voltage source converter satisfies:

[0169] u Md_con =Δu Md +u Md _ ref -u Md

[0170] Among them, u Md_con The modulated voltage d-axis component, Δu, represents the voltage source converter. Md u represents the AC voltage correction value of a voltage source converter. Md_ref The d-axis component of the AC voltage reference value of the voltage source converter, u Md The d-axis component represents the actual output voltage value of a voltage source converter.

[0171] The d-axis component i of the voltage source converter output current reference value Md_ref The d-axis component i of the actual output current of the voltage source converter Md The difference is used for proportional-integral control to obtain the d-axis component i of the modulation current of the voltage source converter. Md1 The q-axis component i of the voltage source converter output current reference value. Mq_ref The q-axis component i of the actual output current of the voltage source converter Mq The difference is used for proportional-integral control to obtain the q-axis component i of the modulation current of the voltage source converter. Mq1 .

[0172] Based on the d-axis component i of the modulation current of the voltage source converter Md1 Calculate the d-axis component i of the output current control signal of the voltage source converter. Md_con According to the q-axis component i of the modulation current of the voltage source converter Mq1 Calculate the q-axis component i of the output current control signal of the voltage source converter. Mq_con .

[0173] The d-axis and q-axis components of the output current control signal of a voltage source converter satisfy the following:

[0174] i Md_con =u Md +i Md1 -ωLi Md

[0175] i Mq_con =u Mq +i Mq1 +ωLi Mq

[0176] Among them, i Md_com The d-axis component of the output current control signal of a voltage source converter, u Md i represents the d-axis component of the actual output voltage of a voltage source converter. Md1 i represents the d-axis component of the modulation current of a voltage source converter. Md The d-axis component represents the actual value of the output current of a voltage source converter. Mq_con u represents the q-axis component of the output current control signal of a voltage source converter. Mq i represents the q-axis component of the actual output voltage of a voltage source converter. Mq1 i represents the q-axis component of the modulation current of a voltage source converter. Mq This represents the q-axis component of the actual output current of the voltage source converter. ω represents the angular frequency of the voltage source converter, and L represents the inductance of the bridge arm inductor in the voltage source converter.

[0177] Example 3:

[0178] 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 realize the steps of the steady-state control method provided in the above embodiments.

[0179] Example 4:

[0180] 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 a high-speed RAM memory or a 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 steady-state control method provided in the above embodiments.

[0181] 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.

[0182] 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 process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0183] 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.

[0184] 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.

[0185] 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 steady-state control method for a hybrid-source DC transformer, the hybrid-source DC transformer comprising a voltage source converter and a current source converter connected in parallel; characterized in that, The steady-state control method includes: The reactive power reference value and AC voltage reference value of the voltage source converter are determined based on the active power reference value of the hybrid source DC transformer. The current source converter is controlled based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer. The voltage source converter is controlled based on the AC voltage reference value and the active power reference value of the voltage source converter.

2. The steady-state control method according to claim 1, characterized in that, The step of determining the reactive power reference value and AC voltage reference value of the voltage source converter based on the active power reference value of the hybrid source DC transformer includes: The reactive power reference value of the voltage source converter is obtained by performing droop control on the actual reactive power value of the voltage source converter based on the active power reference value of the hybrid source DC transformer. Based on the active power reference value of the hybrid source DC transformer, the actual output voltage value of the voltage source converter is droop-controlled to obtain the AC voltage reference value of the voltage source converter.

3. The steady-state control method according to claim 2, characterized in that, The reactive power reference value and the AC voltage reference value of the voltage source converter satisfy the following: Q VSC_ref = k PQ P ref + con PQ u Md_ref =k PV P ref +con PV Among them, Q VSC_ref u represents the reactive power reference value of the voltage source converter. Md_ref P represents the AC voltage reference value of the voltage source converter. ref This represents the active power reference value of the hybrid-source DC transformer; k PQ This represents the active-reactive droop control coefficient, which satisfies... con PQ This represents the active-reactive droop control correction amount, satisfying con PQ =Q VSC_min -k PQ P ref_min k PV This represents the active power-voltage droop control coefficient, which satisfies... con PV This represents the active-voltage droop control correction amount, satisfying con PV =u Md_min -k PV P ref_min Q VSC_max Q represents the maximum reactive power of the voltage source converter. VSC_min This represents the minimum reactive power of the voltage source converter; u Md_max u represents the maximum AC voltage of the voltage source converter. Md_min P represents the minimum AC voltage of the voltage source converter; ref_max P represents the maximum active power of the hybrid-source DC transformer. ref_min This represents the minimum active power of the hybrid-source DC transformer.

4. The steady-state control method according to claim 1, characterized in that, The control of the current source converter based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer includes: Based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer, the actual DC voltage value of the hybrid source DC transformer and the actual output current value of the current source converter are subjected to voltage and current dual closed-loop control to obtain the output current modulation amount of the current source converter. Calculate the phase shift angle and bridge arm straight-through angle of the current source converter based on the output current modulation amount of the current source converter; Based on the voltage value of the filter capacitor in the current source converter, the phase shift angle and bridge arm through-angle of the current source converter are modulated by a dual-degree-of-freedom fundamental frequency, and the first modulation signal is output to the current source converter.

5. The steady-state control method according to claim 4, characterized in that, The step of performing voltage and current dual closed-loop control on the actual DC voltage value of the hybrid-source DC transformer and the actual output current value of the current-source converter based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid-source DC transformer, to obtain the output current modulation amount of the current-source converter, includes: The difference between the DC voltage reference value and the actual DC voltage value of the hybrid source DC transformer is subjected to proportional-integral control to obtain the d-axis component of the output current reference value of the current source converter; the difference between the reactive power reference value and the actual reactive power value of the voltage source converter is subjected to proportional-integral control to obtain the q-axis component of the output current reference value of the current source converter. The actual output current value of the current source converter is subjected to Parker transformation to obtain the d-axis and q-axis components of the actual output current value of the current source converter. The difference between the d-axis component of the current source converter output current reference value and the d-axis component of the current source converter output current actual value is subjected to proportional-integral control to obtain the d-axis modulation amount of the current source converter output current; the difference between the q-axis component of the current source converter output current reference value and the q-axis component of the current source converter output current actual value is subjected to proportional-integral control to obtain the q-axis modulation amount of the current source converter output current.

6. The steady-state control method according to claim 4, characterized in that, The phase shift angle and arm straight-through angle of the current source converter satisfy the following: Where α represents the phase shift angle of the current source converter, θ represents the straight-through angle of the bridge arm of the current source converter, and i fd_con i represents the d-axis component of the output current modulation of the current source converter. fq_con i represents the q-axis component of the output current modulation of the current source converter. L This represents the actual value of the DC current in the hybrid DC converter.

7. The steady-state control method according to claim 1, characterized in that, The control of the voltage source converter based on the AC voltage reference value and active power reference value of the voltage source converter includes: The actual active power of the voltage source converter is calculated based on the actual output current and actual output voltage of the voltage source converter. The difference between the reference active power value and the actual active power value of the voltage source converter is then subjected to proportional-integral control to obtain the AC voltage correction amount of the voltage source converter. Based on the AC voltage correction value and AC voltage reference value of the voltage source converter, the actual output current value and actual output voltage value of the voltage source converter are subjected to voltage and current dual closed-loop control to obtain the output current control signal of the voltage source converter; The output current control signal of the voltage source converter is subjected to inverse Parker transformation and modulation, and a second modulation signal is output to the voltage source converter.

8. The steady-state control method according to claim 7, characterized in that, The step of performing dual closed-loop voltage and current control on the actual output current and actual output voltage of the voltage source converter based on the AC voltage correction value and AC voltage reference value of the voltage source converter to obtain the output current control signal of the voltage source converter includes: A Parker transformation is performed on the actual output current value of the voltage source converter to obtain the d-axis and q-axis components of the actual output current value of the voltage source converter; a Parker transformation is also performed on the actual output voltage value of the voltage source converter to obtain the d-axis and q-axis components of the actual output voltage value of the voltage source converter. The d-axis component of the modulation voltage of the voltage source converter is calculated based on the d-axis component of the actual output voltage of the voltage source converter and the AC voltage correction. Proportional-integral control is then applied to the d-axis component of the modulation voltage of the voltage source converter to obtain the d-axis component of the output current reference value of the voltage source converter. Proportional-integral control is then applied to the difference between the q-axis component of the AC voltage reference value of the voltage source converter and the q-axis component of the actual output voltage of the voltage source converter to obtain the q-axis component of the output current reference value of the voltage source converter. The difference between the d-axis component of the voltage source converter output current reference value and the d-axis component of the actual voltage source converter output current is subjected to proportional-integral control to obtain the d-axis component of the voltage source converter modulation current; the difference between the q-axis component of the voltage source converter output current reference value and the q-axis component of the actual voltage source converter output current is subjected to proportional-integral control to obtain the q-axis component of the voltage source converter modulation current. The d-axis component of the output current control signal of the voltage source converter is calculated based on the d-axis component of the modulation current of the voltage source converter, and the q-axis component of the output current control signal of the voltage source converter is calculated based on the q-axis component of the modulation current of the voltage source converter.

9. The steady-state control method according to claim 8, characterized in that, The modulation voltage d-axis component of the voltage source converter satisfies: u Md_con =Du Md +u Md_ref -u Md Among them, u Md_con The modulated voltage d-axis component Δu of the voltage source converter is represented by this component. Md u represents the AC voltage correction amount of the voltage source converter. Md_ref The d-axis component of the AC voltage reference value of the voltage source converter, u Md The d-axis component represents the actual value of the output voltage of the voltage source converter.

10. The steady-state control method according to claim 8, characterized in that, The d-axis and q-axis components of the output current control signal of the voltage source converter satisfy the following: the Md_con =the Md +i Md1 -ωLi Md the Md_con =the Mq +i Mq1 +ωLi Mq Among them, i Md_con The d-axis component of the output current control signal of the voltage source converter, u Md i represents the d-axis component of the actual output voltage of the voltage source converter. Md1 i represents the d-axis component of the modulation current of the voltage source converter. Md The d-axis component represents the actual value of the output current of the voltage source converter; i Mq_con The q-axis component of the output current control signal of the voltage source converter, u Mq i represents the q-axis component of the actual output voltage of the voltage source converter. Mq1 i represents the q-axis component of the modulation current of the voltage source converter. Mq ω represents the q-axis component of the actual output current of the voltage source converter; ω represents the angular frequency of the voltage source converter; and L represents the inductance of the bridge arm inductor in the voltage source converter.

11. A steady-state control device for a hybrid-source DC transformer, wherein the hybrid-source DC transformer comprises a voltage source converter and a current source converter connected in parallel; characterized in that, The steady-state control device includes: The determination module is used to determine the reactive power reference value and AC voltage reference value of the voltage source converter based on the active power reference value of the hybrid source DC transformer. The first control module is used to control the current source converter according to the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer; The second control module is used to control the voltage source converter according to the AC voltage reference value and active power reference value of the voltage source converter.

12. The steady-state control device according to claim 11, characterized in that, The determining module is specifically used for: The reactive power reference value of the voltage source converter is obtained by performing droop control on the actual reactive power value of the voltage source converter based on the active power reference value of the hybrid source DC transformer. Based on the active power reference value of the hybrid source DC transformer, the actual output voltage value of the voltage source converter is droop-controlled to obtain the AC voltage reference value of the voltage source converter.

13. The steady-state control device according to claim 12, characterized in that, The reactive power reference value and the AC voltage reference value of the voltage source converter satisfy the following: Q VSC_ref =k PQ P ref +con PQ u Md_ref =k PV P ref +con PV Among them, Q VSC_ref u represents the reactive power reference value of the voltage source converter. Md_ref P represents the AC voltage reference value of the voltage source converter. ref This represents the active power reference value of the hybrid-source DC transformer; k PQ This represents the active-reactive droop control coefficient, which satisfies... con PQ This represents the active-reactive droop control correction amount, satisfying con PQ =Q VSC_min -k PQ P ref_min k PV This represents the active power-voltage droop control coefficient, which satisfies... con PV This represents the active-voltage droop control correction amount, satisfying con PV =u Md_min -k PV P ref_min Q VSC_max Q represents the maximum reactive power of the voltage source converter. VSC_min This represents the minimum reactive power of the voltage source converter; u Md_max u represents the maximum AC voltage of the voltage source converter. Md_min P represents the minimum AC voltage of the voltage source converter; ref_max P represents the maximum active power of the hybrid-source DC transformer. ref_min This represents the minimum active power of the hybrid-source DC transformer.

14. The steady-state control device according to claim 11, characterized in that, The first control module is specifically used for: Based on the reactive power reference value of the voltage source converter and the DC voltage reference value of the hybrid source DC transformer, the actual DC voltage value of the hybrid source DC transformer and the actual output current value of the current source converter are subjected to voltage and current dual closed-loop control to obtain the output current modulation amount of the current source converter. Calculate the phase shift angle and bridge arm straight-through angle of the current source converter based on the output current modulation amount of the current source converter; Based on the voltage value of the filter capacitor in the current source converter, the phase shift angle and bridge arm through-angle of the current source converter are modulated by a dual-degree-of-freedom fundamental frequency, and the first modulation signal is output to the current source converter.

15. The steady-state control device according to claim 14, characterized in that, The first control module is specifically used for: The difference between the DC voltage reference value and the actual DC voltage value of the hybrid source DC transformer is subjected to proportional-integral control to obtain the d-axis component of the output current reference value of the current source converter; the difference between the reactive power reference value and the actual reactive power value of the voltage source converter is subjected to proportional-integral control to obtain the q-axis component of the output current reference value of the current source converter. The actual output current value of the current source converter is subjected to Parker transformation to obtain the d-axis and q-axis components of the actual output current value of the current source converter. The difference between the d-axis component of the current source converter output current reference value and the d-axis component of the current source converter output current actual value is subjected to proportional-integral control to obtain the d-axis modulation amount of the current source converter output current; the difference between the q-axis component of the current source converter output current reference value and the q-axis component of the current source converter output current actual value is subjected to proportional-integral control to obtain the q-axis modulation amount of the current source converter output current.

16. The steady-state control device according to claim 14, characterized in that, The phase shift angle and arm straight-through angle of the current source converter satisfy the following: Where α represents the phase shift angle of the current source converter, θ represents the straight-through angle of the bridge arm of the current source converter, and i fd_con i represents the d-axis component of the output current modulation of the current source converter. fq_con i represents the q-axis component of the output current modulation of the current source converter. L This represents the actual value of the DC current in the hybrid DC converter.

17. The steady-state control device according to claim 11, characterized in that, The second control module is specifically used for: The actual active power of the voltage source converter is calculated based on the actual output current and actual output voltage of the voltage source converter. The difference between the reference active power value and the actual active power value of the voltage source converter is then subjected to proportional-integral control to obtain the AC voltage correction amount of the voltage source converter. Based on the AC voltage correction value and AC voltage reference value of the voltage source converter, the actual output current value and actual output voltage value of the voltage source converter are subjected to voltage and current dual closed-loop control to obtain the output current control signal of the voltage source converter; The output current control signal of the voltage source converter is subjected to inverse Parker transformation and modulation, and a second modulation signal is output to the voltage source converter.

18. The steady-state control device according to claim 17, characterized in that, The second control module is specifically used for: A Parker transformation is performed on the actual output current value of the voltage source converter to obtain the d-axis and q-axis components of the actual output current value of the voltage source converter; a Parker transformation is also performed on the actual output voltage value of the voltage source converter to obtain the d-axis and q-axis components of the actual output voltage value of the voltage source converter. The d-axis component of the modulation voltage of the voltage source converter is calculated based on the d-axis component of the actual output voltage of the voltage source converter and the AC voltage correction. Proportional-integral control is then applied to the d-axis component of the modulation voltage of the voltage source converter to obtain the d-axis component of the output current reference value of the voltage source converter. Proportional-integral control is then applied to the difference between the q-axis component of the AC voltage reference value of the voltage source converter and the q-axis component of the actual output voltage of the voltage source converter to obtain the q-axis component of the output current reference value of the voltage source converter. The difference between the d-axis component of the voltage source converter output current reference value and the d-axis component of the actual voltage source converter output current is subjected to proportional-integral control to obtain the d-axis component of the voltage source converter modulation current; the difference between the q-axis component of the voltage source converter output current reference value and the q-axis component of the actual voltage source converter output current is subjected to proportional-integral control to obtain the q-axis component of the voltage source converter modulation current. The d-axis component of the output current control signal of the voltage source converter is calculated based on the d-axis component of the modulation current of the voltage source converter, and the q-axis component of the output current control signal of the voltage source converter is calculated based on the q-axis component of the modulation current of the voltage source converter.

19. The steady-state control device according to claim 18, characterized in that, The modulation voltage d-axis component of the voltage source converter satisfies: u Md_con =Du Md +u Md_ref -u Md Among them, u Md_con The modulated voltage d-axis component Δu of the voltage source converter is represented by this component. Md u represents the AC voltage correction amount of the voltage source converter. Md_ref The d-axis component of the AC voltage reference value of the voltage source converter, u Md The d-axis component represents the actual value of the output voltage of the voltage source converter.

20. The steady-state control device according to claim 18, characterized in that, The d-axis and q-axis components of the output current control signal of the voltage source converter satisfy the following: the Md_con =the Md +i Md1 -ωLi Md the Md_con =the Mq +i Mq1 +ωLi Mq Among them, i Md_con The d-axis component of the output current control signal of the voltage source converter, u Md i represents the d-axis component of the actual output voltage of the voltage source converter. Md1 i represents the d-axis component of the modulation current of the voltage source converter. Md The d-axis component represents the actual value of the output current of the voltage source converter; i Mq_con The q-axis component of the output current control signal of the voltage source converter, u Mq i represents the q-axis component of the actual output voltage of the voltage source converter. Mq1 i represents the q-axis component of the modulation current of the voltage source converter. Mq ω represents the q-axis component of the actual output current of the voltage source converter; ω represents the angular frequency of the voltage source converter; and L represents the inductance of the bridge arm inductor in the voltage source 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 steady-state 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 steady-state control method as described in any one of claims 1 to 10.

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