Converter station control method, system and equipment and storage medium

Abstract

The embodiment of the invention discloses a control method, system and equipment of a converter station and a storage medium, constant voltage-frequency control in the embodiment of the invention is suitable for the condition that the voltage is stabilized in a preset threshold range, and constant voltage-frequency control is performed on a given frequency to obtain a first reference angle; the first voltage actual value and the first current actual value are obtained by using the first reference angle, and the converter station is controlled by using the first voltage actual value and the first current actual value, so that efficient operation of the converter station under a normal voltage condition can be ensured; the phase-locked loop control plays a role when the voltage is abnormal, the phase-locked loop control is carried out on the three-phase voltage and the given frequency to obtain a second reference angle, the voltage change can be quickly and accurately tracked to obtain a proper reference angle, and a second voltage actual value and a second current actual value are obtained by utilizing the second reference angle; and the converter station is controlled by using the second voltage actual value and the second current actual value, so that effective control of the converter station is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of converter station control, and in particular to a control method, system, device and storage medium for a converter station. Background Art

[0002] In converter station control, the phase of the control signal is primarily determined by the modulation signal generated by dual closed-loop control. As the voltage returns to normal, the modulation signal continues to change, and the resulting phase will also continue to change. At this point, if the Park transform's rotational speed remains constant at the reference angle obtained by constant voltage-frequency control, the converter station's inner current control loop will fail, leading to failure of the entire converter station's control chain and exacerbating overvoltage issues. Summary of the Invention

[0003] In view of this, the present invention provides a control method, system, device and storage medium for a converter station.

[0004] The specific technical solution of the first embodiment of the present invention is: a control method for a converter station, the method comprising: obtaining the three-phase voltage and three-phase current at the AC bus of the converter station, and obtaining the given frequency of the converter station; judging whether the effective value of the three-phase voltage is within a preset threshold range; when the effective value of the voltage is within the preset threshold range, performing constant voltage-frequency control on the given frequency to obtain a first reference angle; using the first reference angle, the three-phase voltage and the three-phase current to obtain a first voltage actual value and a first current actual value, and using the first voltage actual value and the first current actual value to control the converter station; when the effective value of the voltage is not within the preset threshold range, performing phase-locked loop control on the three-phase voltage and the given frequency to obtain a second reference angle; using the second reference angle, the three-phase voltage and the three-phase current to obtain a second voltage actual value and a second current actual value, and using the second voltage actual value and the second current actual value to control the converter station.

[0005] Preferably, the phase-locked loop control of the three-phase voltage and the given frequency to obtain the second reference angle includes: obtaining the fundamental angular frequency corresponding to the given frequency; performing Park transformation and PI regulation on the three-phase voltage to obtain an angular frequency change; adding the angular frequency change to the fundamental angular frequency to obtain a reference angular frequency; and integrating the reference angular frequency to obtain the second reference angle.

[0006] Preferably, performing Park transformation and PI regulation on the three-phase voltage to obtain the angular frequency variation includes: performing Park transformation on the three-phase voltage to obtain the actual value of the d-axis voltage and the actual value of the q-axis voltage; and performing PI regulation on the actual value of the q-axis voltage to obtain the angular frequency variation.

[0007] Preferably, the method of obtaining the first voltage actual value and the first current actual value by using the first reference angle, the three-phase voltage and the three-phase current includes: performing a Park transformation on the three-phase voltage using the first reference angle to obtain a first d-axis voltage and a first q-axis voltage; the first d-axis voltage and the first q-axis voltage constitute the first voltage actual value; performing a Park transformation on the three-phase current using the first reference angle to obtain a first d-axis current and a first q-axis current; the first d-axis current and the first q-axis current constitute the first current actual value.

[0008] Preferably, the first d-axis voltage and the first q-axis voltage are obtained using the following formula:

[0009]

[0010] Among them, u d is the first d-axis voltage, u q is the first q-axis voltage, u0 is the 0-axis voltage, θ0 is the first reference angle, u a 、u b and u c are the three-phase voltages, and A1, A2, A3 and A4 are constants.

[0011] Preferably, the first d-axis current and the first q-axis current are obtained using the following formula:

[0012]

[0013] Among them, i d is the first d-axis current, i q is the first q-axis current, i0 is the 0-axis current, θ0 is the first reference angle, i a 、i b and i c are the three-phase voltages, and A5, A6, A7, and A8 are constants.

[0014] Preferably, the control of the converter station using the first voltage actual value and the first current actual value includes: obtaining a voltage reference value of the converter station; obtaining a voltage error based on the first voltage actual value and the voltage reference value, and performing PI adjustment on the voltage error to obtain a current reference value; obtaining a current error based on the first current actual value and the current reference value, and performing PI adjustment on the current error to obtain a current regulation amount; integrating the current regulation amount into a modulation signal, and using the modulation signal to control the converter station.

[0015] The specific technical solution of the second embodiment of the present invention is: a control system of a converter station, the system comprising: a data acquisition module, a judgment module, a first conversion module, a first control module, a second conversion module and a second control module; the data acquisition module is used to obtain the three-phase voltage and three-phase current at the AC bus of the converter station, and obtain the given frequency of the converter station; the judgment module is used to determine whether the effective value of the three-phase voltage is within a preset threshold range; the first conversion module is used to perform constant voltage-frequency control on the given frequency to obtain a first reference angle when the effective value of the voltage is within the preset threshold range; the first control module is used to The first reference angle, the three-phase voltage and the three-phase current are used to obtain a first voltage actual value and a first current actual value, and the first voltage actual value and the first current actual value are used to control the converter station; the second conversion module is used to perform phase-locked loop control on the three-phase voltage and the given frequency to obtain a second reference angle when the effective value of the voltage is not within the preset threshold range; the second control module is used to obtain a second voltage actual value and a second current actual value by using the second reference angle, the three-phase voltage and the three-phase current, and the second voltage actual value and the second current actual value are used to control the converter station.

[0016] The specific technical solution of the third embodiment of the present invention is: a control device of a converter station, including a memory and a processor, the memory storing a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method described in any one of the first embodiments of the present application.

[0017] The specific technical solution of the fourth embodiment of the present invention is: a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to perform the steps of the method described in any one of the first embodiments of the present application.

[0018] The implementation of the present invention will have the following beneficial effects:

[0019] The application realizes accurate control of the converter station under different voltage conditions by using constant voltage-frequency control and phase-locked loop control according to whether the effective value of three-phase voltage is within a preset threshold range. The constant voltage-frequency control is suitable for the case that the voltage is stable within the preset threshold range, and the first reference angle is obtained by performing constant voltage-frequency control on the given frequency, the first voltage actual value and the first current actual value are obtained by using the first reference angle, and the converter station is controlled by using the first voltage actual value and the first current actual value, so that efficient operation of the converter station under normal voltage conditions can be ensured. The phase-locked loop control plays a role when the voltage is abnormal, and the second reference angle is obtained by performing phase-locked loop control on the three-phase voltage and the given frequency, so that the voltage change can be quickly and accurately tracked to obtain a suitable reference angle, the second voltage actual value and the second current actual value are obtained by using the second reference angle, and the converter station is controlled by using the second voltage actual value and the second current actual value, thereby realizing effective control of the converter station. The control mode switching strategy according to the actual voltage condition greatly improves the adaptability and accuracy of the converter station control, ensures the stability of the control link of the entire converter station, and improves the overall performance of the converter station. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 Step flow chart of the control method of the converter station;

[0022] Figure 2 Simplified model diagram of the converter station;

[0023] Figure 3 Model diagram for obtaining the first reference angle;

[0024] Figure 4 Model diagram for obtaining the second reference angle;

[0025] Figure 5 Step flow chart for obtaining the second reference angle;

[0026] Figure 6 Step flow chart for controlling the converter station;

[0027] Figure 7 Structure diagram of the control system of the converter station;

[0028] Figure 8 Internal structure diagram of the computer device;

[0029] Among them, 401 is a data acquisition module; 402 is a judgment module; 403 is a first conversion module; 404 is a first control module; 405 is a second conversion module; and 406 is a second control module. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0031] The terms "first," "second," and the like in the specification, claims, and drawings of this application are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or modules is not limited to the listed steps or modules but may optionally include steps or modules not listed, or may optionally include other steps or modules inherent to the process, method, product, or apparatus.

[0032] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] See also Figure 1 , is a flowchart of a control method for a converter station in the first embodiment of the present application, which can improve the overall performance of the converter station. The method includes:

[0034] Step 101: Acquire the three-phase voltage and three-phase current at the AC busbar of the converter station, and acquire the given frequency of the converter station;

[0035] Step 102: Determine whether the effective value of the three-phase voltage is within a preset threshold range;

[0036] Specifically, the preset threshold range can be set according to actual conditions, such as between 0.9pu and 1.1pu, to determine the effective value u of the three-phase voltage. s Is it between 0.9pu and 1.1pu?

[0037] Step 103: When the voltage effective value is within the preset threshold range, performing constant voltage-frequency control on the given frequency to obtain a first reference angle;

[0038] Step 104: Obtain a first voltage actual value and a first current actual value using the first reference angle, the three-phase voltage, and the three-phase current, and control the converter station using the first voltage actual value and the first current actual value.

[0039] Step 105: When the voltage effective value is not within the preset threshold range, performing phase-locked loop control on the three-phase voltage and the given frequency to obtain a second reference angle;

[0040] Step 106: Obtain a second voltage actual value and a second current actual value using the second reference angle, the three-phase voltage, and the three-phase current, and control the converter station using the second voltage actual value and the second current actual value.

[0041] For a simplified model of the converter station, please refer to Figure 2 , three-phase voltage including u a 、u b and u c , the three-phase current includes i a 、i b and i c , the given frequency can be set according to the actual situation, such as 50Hz. Specifically, the three-phase voltage includes the voltages of phases A, B, and C on the AC bus of the converter station. Each phase voltage is a vector with magnitude and phase information. There is a specific phase difference between the three-phase voltages (in a three-phase balanced system, the phase difference is 120°), and they together constitute a three-phase AC voltage system. For example, in a three-phase AC power system, the instantaneous values ​​of the A-phase voltage, the B-phase voltage, and the C-phase voltage change with time according to the sinusoidal law, and the phases lag by 120° respectively. When the effective value of the three-phase voltage u s When the frequency is between 0.9 pu and 1.1 pu, the first reference angle θ0 is obtained by performing constant voltage-frequency control on the given frequency. Figure 3 The given frequency of the converter station is 50Hz, and its corresponding fundamental angular frequency is ω0. The first reference angle θ0 is obtained by integrating ω0. The first voltage actual value and the first current actual value are obtained by using the first reference angle θ0, the three-phase voltage and the three-phase current, and the converter station is controlled by using the first voltage actual value and the first current actual value. When the voltage effective value u sWhen it is less than 0.9pu or greater than 1.1pu, the three-phase voltage and the given frequency are subjected to phase-locked loop control to obtain the second reference angle θ1, and the second reference angle θ1, the three-phase voltage and the three-phase current are used to obtain the second voltage actual value and the second current actual value, and the second voltage actual value and the second current actual value are used to control the converter station.

[0042] The method in this embodiment can employ constant voltage-frequency control and phase-locked loop (PLL) control, respectively, depending on whether the three-phase voltage effective value is within a preset threshold range, thereby achieving precise control of the converter station under different voltage conditions. Constant voltage-frequency control is applicable when the voltage is stable within a preset threshold range. Constant voltage-frequency control is applied to a given frequency to obtain a first reference angle. The first reference angle is used to obtain a first voltage actual value and a first current actual value. These values ​​are then used to control the converter station, ensuring efficient operation of the converter station under normal voltage conditions. Phase-locked loop control, on the other hand, is effective when voltage is abnormal. Phase-locked loop control is applied to the three-phase voltage and given frequency to obtain a second reference angle. This allows for rapid and accurate tracking of voltage changes to obtain a suitable reference angle. The second reference angle is used to obtain a second voltage actual value and a second current actual value. These values ​​are then used to control the converter station, thereby achieving effective control of the converter station. This strategy of flexibly switching control modes based on actual voltage conditions significantly improves the adaptability and precision of converter station control, ensuring stability in the control chain of the entire converter station and enhancing the overall performance of the converter station.

[0043] In the specific embodiment, see Figure 4 In step 105, performing phase-locked loop control on the three-phase voltage and the given frequency to obtain a second reference angle includes:

[0044] Step 201: Obtain the fundamental angular frequency corresponding to the given frequency;

[0045] Step 202: Perform Park transformation and PI regulation on the three-phase voltage to obtain an angular frequency variation;

[0046] Step 203: Add the angular frequency variation to the fundamental wave angular frequency to obtain a reference angular frequency;

[0047] Step 204: Integrate the reference angular frequency to obtain the second reference angle.

[0048] In a specific embodiment, performing Park transformation and PI regulation on the three-phase voltage to obtain the angular frequency variation includes: performing Park transformation on the three-phase voltage to obtain the actual value of the d-axis voltage and the actual value of the q-axis voltage; and performing PI regulation on the actual value of the q-axis voltage to obtain the angular frequency variation.

[0049] For details, please refer to Figure 5 , the phase-locked loop phase-locks the three-phase voltage of the AC busbar of the converter station, tracks its phase change, and outputs the second reference angle θ1. The specific process is: a 、u b and u c The actual value of the d-axis voltage u is obtained by Park transformation d and the actual value of the q-axis voltage u q ; Actual value of q-axis voltage u q After passing through the PI controller, the voltage reference angular frequency ω1 is added to the fundamental angular frequency ω0. The reference angular frequency ω1 is integrated to output the voltage phase and fed back as the second reference angle θ1 of the Park transformation. q Adjust to zero, the PI controller dynamically adjusts the reference angular frequency to keep the voltage phase synchronized with the grid voltage phase without the need for an additional phase detection circuit. q Using feedback information for control avoids complex phase calculations or additional phase detection steps. The integral action of the PI controller can eliminate steady-state errors, ensuring that the system can quickly and accurately restore synchronization when the grid voltage and frequency fluctuate or the phase suddenly changes.

[0050] In a specific embodiment, obtaining the first voltage actual value and the first current actual value using the first reference angle, the three-phase voltage, and the three-phase current includes: performing a Park transform on the three-phase voltage using the first reference angle to obtain a first d-axis voltage and a first q-axis voltage; the first d-axis voltage and the first q-axis voltage constitute the first voltage actual value; performing a Park transform on the three-phase current using the first reference angle to obtain a first d-axis current and a first q-axis current; the first d-axis current and the first q-axis current constitute the first current actual value. Specifically, in a rotating coordinate system, the d-axis component generally represents the active power component, and the q-axis component represents the reactive power component. Through the Park transform, the three-phase AC quantity is decoupled into two independent DC components, facilitating separate control. The Park transform converts the abc quantities into dq quantities, converting AC signals that are difficult to directly control into DC signals, thereby achieving simpler, more efficient, and more precise control. In three-phase control, the controller needs to track dynamic changes, resulting in slow response and poor control accuracy. DC control simplifies controller design, requiring only a PI controller for precise regulation.

[0051] In a specific embodiment, the first d-axis voltage and the first q-axis voltage are obtained using the following formula:

[0052]

[0053] Among them, u d is the first d-axis voltage, u qis the first q-axis voltage, u0 is the 0-axis voltage, θ0 is the first reference angle, u a 、u b and u c are the three-phase voltages, and A1, A2, A3 and A4 are constants.

[0054] In a specific embodiment, the first d-axis current and the first q-axis current are obtained using the following formula:

[0055]

[0056] Among them, i d is the first d-axis current, i q is the first q-axis current, i0 is the 0-axis current, θ0 is the first reference angle, i a 、i b and i c are the three-phase voltages, and A5, A6, A7, and A8 are constants.

[0057] Specifically, the second d-axis voltage, the second q-axis voltage, the second d-axis current, and the second q-axis current can be obtained by replacing the first reference angle θ0 in the formula for obtaining the first d-axis voltage, the first q-axis voltage, the first d-axis current, and the first q-axis current with the second reference angle θ1. The second d-axis voltage and the second q-axis voltage constitute the second voltage actual value, and the second d-axis current and the second q-axis current constitute the second current actual value.

[0058] Specifically, when the voltage effective value is within the preset threshold range, the first voltage actual value u is obtained using the following formula: a 、u b and u c and the first current actual value i a 、i b and i c :

[0059]

[0060] When the voltage effective value is not within the preset threshold range, the second voltage actual value u is obtained using the following formula: a ′、u b ′ and u c ' and the second current actual value i a ′、i b ′ and i c ′:

[0061]

[0062] In the specific embodiment, see Figure 6, the controlling the converter station by using the first voltage actual value and the first current actual value includes:

[0063] Step 301: Obtain a voltage reference value of the converter station;

[0064] Step 302: Obtain a voltage error according to the first voltage actual value and the voltage reference value, and perform PI regulation on the voltage error to obtain a current reference value;

[0065] Step 303: Obtain a current error according to the first current actual value and the current reference value, and perform PI regulation on the current error to obtain a current regulation value;

[0066] Step 304: Integrate the current regulation amount into a modulation signal, and use the modulation signal to control the converter station.

[0067] Specifically, by comparing the actual value of the first voltage with the voltage reference value to obtain the voltage error, calculating the voltage error and performing PI adjustment, the output voltage of the converter station can be accurately controlled to stabilize it at the set value; the PI regulator can quickly respond to changes in voltage and current, dynamically adjust the control quantity, and improve the dynamic performance of the system. By providing real-time feedback on voltage and current values, the system can automatically compensate for errors and maintain output stability.

[0068] This embodiment uses a phase-locked loop (PLL) to track the phase changes of the converter station's AC bus voltage and obtain the corresponding phase angle. When the voltage is within the specified range, the angle of the converter station's AC bus voltage and current Park transformation is achieved using constant voltage-frequency control. When the converter station's AC voltage is less than 0.9 pu or greater than 1.1 pu, the angle obtained by the PLL is applied to the voltage and current Park transformation.

[0069] The flexible direct current (DC) sending-end converter station adopts a grid-type control to provide reference voltage and phase for the sending-end AC system. When a fault occurs, its voltage changes dramatically. Not only does the voltage amplitude change, but its phase also keeps changing. In the control of the converter station, its phase is mainly determined by the modulation signal obtained by its dual closed-loop control. During the process of voltage recovery, its modulation signal keeps changing, so the obtained phase will keep changing. At this time, if the rotation speed of the Park transformation is always kept at the value obtained by the constant voltage-frequency control, the current inner loop control of the controller will fail, and then the entire control link will fail, exacerbating the overvoltage problem. This embodiment adds a phase-locked link to the control link of the converter station, and uses the phase-locked loop to timely track the phase change of the converter station AC bus voltage, and applies the obtained angle to the Park transformation of the AC bus current, thereby reducing the impact of control failure caused by voltage phase change during voltage recovery after the fault disappears.

[0070] In the specific embodiment, see Figure 7 , is a structural diagram of a control system of a converter station in the second embodiment of the present application, the system comprising: a data acquisition module 401, a judgment module 402, a first conversion module 403, a first control module 404, a second conversion module 405 and a second control module 406; the data acquisition module 401 is used to obtain the three-phase voltage and three-phase current at the AC bus of the converter station, and to obtain the given frequency of the converter station; the judgment module 402 is used to determine whether the effective value of the three-phase voltage is within a preset threshold range; the first conversion module 403 is used to perform constant voltage-frequency control on the given frequency to obtain a first reference angle when the effective value of the voltage is within the preset threshold range; The first control module 404 is used to obtain a first voltage actual value and a first current actual value using the first reference angle, the three-phase voltage and the three-phase current, and to control the converter station using the first voltage actual value and the first current actual value; the second conversion module 405 is used to perform phase-locked loop control on the three-phase voltage and the given frequency to obtain a second reference angle when the effective value of the voltage is not within the preset threshold range; the second control module 406 is used to obtain a second voltage actual value and a second current actual value using the second reference angle, the three-phase voltage and the three-phase current, and to control the converter station using the second voltage actual value and the second current actual value.

[0071] The system in this embodiment can employ constant voltage-frequency control and phase-locked loop (PLL) control, respectively, depending on whether the three-phase voltage effective value is within a preset threshold range, achieving precise control of the converter station under different voltage conditions. Constant voltage-frequency control is applicable when the voltage is stable within a preset threshold range. Constant voltage-frequency control is applied to a given frequency to obtain a first reference angle. The first reference angle is used to obtain a first voltage actual value and a first current actual value. These values ​​are then used to control the converter station, ensuring efficient operation of the converter station under normal voltage conditions. Phase-locked loop control, on the other hand, is effective when voltage is abnormal. Phase-locked loop control is applied to the three-phase voltage and given frequency to obtain a second reference angle. This allows for rapid and accurate tracking of voltage changes to obtain a suitable reference angle. The second reference angle is used to obtain a second voltage actual value and a second current actual value. These values ​​are then used to control the converter station, achieving effective control of the converter station. This strategy of flexibly switching control modes based on actual voltage conditions significantly improves the adaptability and precision of converter station control, ensuring stability in the control chain of the entire converter station and enhancing its overall performance.

[0072] In a specific embodiment, the third embodiment of the present application provides a control device of a converter station, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described in any one of the first embodiments of the present application.

[0073] In a specific embodiment, the fourth embodiment of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor performs the steps of the method described in any one of the first embodiments of the present application.

[0074] Figure 8 The internal structure of a computer device in one embodiment is shown. The computer device can be a terminal or a server. Figure 8 The computer device includes a processor, a memory, etc. connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor can implement the method of this embodiment. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor can implement the method of this embodiment. It will be understood by those skilled in the art that Figure 8 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0075] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0076] The above description is merely a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any person skilled in the art may utilize the technical contents disclosed above to change or modify them into equivalent embodiments with equivalent changes for application in other fields. However, any simple modification, equivalent change, and modification of the above embodiments made in accordance with the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A control method for a converter station, characterized in that: The method comprises: Obtaining the three-phase voltage and three-phase current at the AC busbar of the converter station, and obtaining the given frequency of the converter station; Determining whether the effective voltage value of the three-phase voltage is within a preset threshold range; When the effective value of the voltage is within the preset threshold range, performing constant voltage-frequency control on the given frequency to obtain a first reference angle; Obtaining a first voltage actual value and a first current actual value by using the first reference angle, the three-phase voltage, and the three-phase current, and controlling the converter station by using the first voltage actual value and the first current actual value; When the voltage effective value is not within the preset threshold range, performing phase-locked loop control on the three-phase voltage and the given frequency to obtain a second reference angle; A second voltage actual value and a second current actual value are obtained using the second reference angle, the three-phase voltage, and the three-phase current, and the second voltage actual value and the second current actual value are used to control the converter station.

2. The control method of the converter station according to claim 1, characterized in that: The performing phase-locked loop control on the three-phase voltage and the given frequency to obtain a second reference angle includes: Obtaining the fundamental angular frequency corresponding to the given frequency; Performing Park transformation and PI regulation on the three-phase voltage to obtain an angular frequency variation; Adding the angular frequency variation to the fundamental wave angular frequency to obtain a reference angular frequency; The second reference angle is obtained by integrating the reference angular frequency.

3. The control method of the converter station according to claim 2, characterized in that: The performing Park transformation and PI regulation on the three-phase voltage to obtain the angular frequency variation includes: Performing Park transformation on the three-phase voltage to obtain an actual value of the d-axis voltage and an actual value of the q-axis voltage; The PI regulation is performed on the actual value of the q-axis voltage to obtain the angular frequency variation.

4. The control method of a converter station according to claim 1, wherein: The obtaining a first voltage actual value and a first current actual value by using the first reference angle, the three-phase voltage, and the three-phase current includes: Performing a Park transform on the three-phase voltage using the first reference angle to obtain a first d-axis voltage and a first q-axis voltage; the first d-axis voltage and the first q-axis voltage constitute the first voltage actual value; Performing a Park transformation on the three-phase current using the first reference angle to obtain a first d-axis current and a first q-axis current; the first d-axis current and the first q-axis current constitute the first current actual value.

5. The control method of the converter station according to claim 4, characterized in that: The first d-axis voltage and the first q-axis voltage are obtained using the following formula: Among them, u d is the first d-axis voltage, u q is the first q-axis voltage, u0 is the 0-axis voltage, θ0 is the first reference angle, u a 、u b and u c are the three-phase voltages, and A1, A2, A3, and A4 are constants.

6. The control method of a converter station according to claim 4, characterized in that: The first d-axis current and the first q-axis current are obtained using the following formula: Among them, i d is the first d-axis current, i q is the first q-axis current, i0 is the 0-axis current, θ0 is the first reference angle, i a 、i b and i c are the three-phase voltages, and A5, A6, A7, and A8 are constants.

7. The control method of a converter station according to claim 1, characterized in that: The controlling the converter station by using the first voltage actual value and the first current actual value includes: Obtaining a voltage reference value of the converter station; Obtaining a voltage error according to the first voltage actual value and the voltage reference value, and performing PI regulation on the voltage error to obtain a current reference value; Obtaining a current error according to the first current actual value and the current reference value, and performing PI regulation on the current error to obtain a current regulation amount; The current regulation amount is integrated into a modulation signal, and the modulation signal is used to control the converter station.

8. A control system for a converter station, characterized in that: The system includes: a data acquisition module, a judgment module, a first conversion module, a first control module, a second conversion module and a second control module; The data acquisition module is used to obtain the three-phase voltage and three-phase current at the AC bus of the converter station, and obtain the given frequency of the converter station; The judging module is used to judge whether the effective value of the three-phase voltage is within a preset threshold range; The first conversion module is configured to perform constant voltage-frequency control on the given frequency to obtain a first reference angle when the effective value of the voltage is within the preset threshold range; The first control module is configured to obtain a first voltage actual value and a first current actual value by using the first reference angle, the three-phase voltage, and the three-phase current, and control the converter station by using the first voltage actual value and the first current actual value; The second conversion module is configured to perform phase-locked loop control on the three-phase voltage and the given frequency to obtain a second reference angle when the voltage effective value is not within the preset threshold range; The second control module is used to obtain a second voltage actual value and a second current actual value using the second reference angle, the three-phase voltage and the three-phase current, and control the converter station using the second voltage actual value and the second current actual value.

9. A control device for a converter station, comprising a memory and a processor, characterized in that: The memory stores a computer program, and when the computer program is executed by the processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

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