Offshore wind power through flexible dc grid connection system starting control method and device

Abstract

The application discloses a kind of offshore wind power through flexible DC grid-connected system starting control method and device, it is related to offshore wind power DC transmission technical field, to offshore converter station and land converter station are not controlled charging, when each land submodule voltage and each offshore submodule voltage are greater than or equal to corresponding first stage voltage value, then to offshore converter station and land converter station are controllable charging, when each land submodule voltage and each offshore submodule voltage are greater than or equal to corresponding second stage voltage value, then based on each offshore submodule voltage and preset DC oscillation suppression model, offshore converter station and land converter station are started operation, the existing starting control method is solved, only consider how to complete the establishment of flexible DC offshore station alternating voltage by control, and the influence of electrical quantity impact on flexible DC converter valve and other equipment during starting process is not considered, reduce the technical problem of offshore wind power through flexible DC grid-connected system reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the offshore wind power DC transmission technology field, especially to a kind of offshore wind power through flexible DC grid-connected system starting control method and device. BACKGROUND

[0002] In recent years, with the development of new energy generation technology and power electronics technology, the VSC-HVDC (flexible DC) is used to transmit large-scale long-distance offshore wind power, and the technical scheme of connecting to the onshore power grid has been widely used. However, there are great differences in DC control function between the offshore wind power through flexible DC grid-connected system and the traditional two-end networking flexible DC, especially in the starting process of DC, the stable AC voltage amplitude and frequency need to be provided to the offshore wind farm to complete the starting of the offshore wind farm.

[0003] The existing offshore wind power through flexible DC grid-connected system starting control method only considers how to control the establishment of the AC voltage of the flexible DC offshore station, and does not consider the impact of the electrical quantity shock on the flexible DC converter valve and other devices during the starting process, which reduces the reliability of the offshore wind power through flexible DC grid-connected system. SUMMARY

[0004] The present application provides an offshore wind power through flexible DC grid-connected system starting control method and device, which solves the technical problem that the existing offshore wind power through flexible DC grid-connected system starting control method only considers how to control the establishment of the AC voltage of the flexible DC offshore station, and does not consider the impact of the electrical quantity shock on the flexible DC converter valve and other devices during the starting process, which reduces the reliability of the offshore wind power through flexible DC grid-connected system.

[0005] The present application provides an offshore wind power through flexible DC grid-connected system starting control method and device, which solves the technical problem that the existing offshore wind power through flexible DC grid-connected system starting control method only considers how to control the establishment of the AC voltage of the flexible DC offshore station, and does not consider the impact of the electrical quantity shock on the flexible DC converter valve and other devices during the starting process, which reduces the reliability of the offshore wind power through flexible DC grid-connected system.

[0006] Real-time acquisition of each land sub-module voltage and each offshore sub-module voltage in the offshore wind power through flexible DC grid-connected system, and uncontrolled charging of the offshore converter station and the land converter station is carried out;

[0007] Determine whether each land sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first stage voltage value;

[0008] When each land sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first stage voltage value, then controllable charging is carried out on the offshore converter station and the land converter station;

[0009] determining whether each of the onshore sub-module voltage and each of the offshore sub-module voltage is greater than or equal to a corresponding second stage voltage value;

[0010] when each of the onshore sub-module voltage and each of the offshore sub-module voltage is greater than or equal to a corresponding second stage voltage value, then based on each of the offshore sub-module voltage and a preset DC oscillation suppression model, starting operation is performed on the offshore converter station and the onshore converter station.

[0011] Optionally, the step of controllably charging the offshore converter station and the onshore converter station comprises:

[0012] controlling the closing of the bypass switch of the starting loop in the onshore converter station, and based on a preset onshore input quantity, charging operation is performed on the onshore sub-module in the onshore converter station;

[0013] based on a preset offshore input quantity, charging operation is performed on the offshore bridge arm in the offshore converter station.

[0014] Optionally, the step of starting operation on the offshore converter station and the onshore converter station based on each of the offshore sub-module voltage and a preset DC oscillation suppression model comprises:

[0015] unlocking the onshore converter station, and acquiring the DC side DC current of the onshore converter station in real time;

[0016] inputting the DC side DC current into a preset DC oscillation suppression model to obtain a DC voltage reference value, wherein the DC oscillation suppression model comprises a difference operator, a filter and a damping coefficient device connected in sequence;

[0017] using the DC voltage reference value to perform DC oscillation suppression operation on the onshore converter station, and based on a preset first ramping rate, controlling the DC voltage of the onshore converter station to gradually increase to a preset DC rated voltage;

[0018] determining whether each of the offshore sub-module voltage is greater than or equal to a preset third stage threshold value,

[0019] if each of the offshore sub-module voltage is greater than or equal to the third stage threshold value, then unlocking the offshore converter station, and based on a preset second ramping rate, unlocking operation is performed on the offshore converter station;

[0020] if any of the offshore sub-module voltage is less than the third stage threshold value, then the step of controllably charging the offshore converter station is performed until each of the offshore sub-module voltage is greater than or equal to the third stage threshold value.

[0021] Optionally, the step of unlocking the offshore converter station based on the preset second ramping rate comprises:

[0022] controlling switching of each offshore sub-module in the offshore converter station through a preset offshore station control target model;

[0023] controlling the AC voltage of the offshore converter station to gradually increase to a preset AC rated voltage based on a preset second ramping rate.

[0024] Optionally, the method further comprises:

[0025] when any of the onshore sub-module voltages or any of the offshore sub-module voltages is less than a corresponding first-stage voltage value, then performing the step of uncontrolled charging of the offshore converter station and the onshore converter station until each of the onshore sub-module voltages and each of the offshore sub-module voltages is greater than or equal to the corresponding first-stage voltage value.

[0026] Optionally, the method further comprises:

[0027] when any of the onshore sub-module voltages or any of the offshore sub-module voltages is less than a corresponding second-stage voltage value, then performing the step of controlled charging of the offshore converter station and the onshore converter station until each of the onshore sub-module voltages and each of the offshore sub-module voltages is greater than or equal to the corresponding second-stage voltage value.

[0028] Optionally, the onshore input quantity configuration process comprises:

[0029] obtaining a DC side voltage of the onshore converter station at a current time, and inputting the DC side voltage and a corresponding second-stage voltage value of the onshore sub-module voltage into a preset onshore input quantity function to obtain an onshore input quantity;

[0030] the onshore input quantity function is specifically:

[0031] ;

[0032] wherein, the onshore input quantity, the DC side voltage, the corresponding second-stage voltage value of the onshore sub-module voltage;

[0033] the offshore input quantity configuration process comprises:

[0034] obtaining an offshore sub-module quantity, and performing ratio processing on the offshore sub-module quantity and a preset input coefficient to obtain an offshore input quantity.

[0035] The second aspect of the present application provides a starting control device for a flexible DC grid-connected system of offshore wind power, which is applied to a flexible DC grid-connected system of offshore wind power, wherein the flexible DC grid-connected system of offshore wind power comprises an onshore converter station and an offshore converter station, and comprises:

[0036] A first starting module is configured to acquire real-time voltages of each onshore sub-module and each offshore sub-module in the flexible DC grid-connected system of offshore wind power, and to perform uncontrolled charging on the offshore converter station and the onshore converter station.

[0037] A first analysis module is configured to determine whether each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to a corresponding first-stage voltage value.

[0038] A second starting module is configured to perform controllable charging on the offshore converter station and the onshore converter station when each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first-stage voltage value.

[0039] A second analysis module is configured to determine whether each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to a corresponding second-stage voltage value.

[0040] An unlocking module is configured to perform starting operation on the offshore converter station and the onshore converter station based on each offshore sub-module voltage and a preset DC oscillation suppression model when each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding second-stage voltage value.

[0041] The third aspect of the present application provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor to make the processor execute the steps of the starting control method of the flexible DC grid-connected system of offshore wind power according to any one of the above aspects.

[0042] The fourth aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed to implement the starting control method of the flexible DC grid-connected system of offshore wind power according to any one of the above aspects.

[0043] From the above technical solutions, the present application has the following advantages:

[0044] The application firstly performs uncontrolled charging on the offshore converter station and the land converter station, when each land submodule voltage and each offshore submodule voltage are greater than or equal to the corresponding first stage voltage value, then performs controllable charging on the offshore converter station and the land converter station, when each land submodule voltage and each offshore submodule voltage are greater than or equal to the corresponding second stage voltage value, then performs starting operation on the offshore converter station and the land converter station based on each offshore submodule voltage and a preset DC oscillation suppression model, which overcomes the technical problem of the existing offshore wind power through flexible DC grid connection system starting control method, only considers how to complete the establishment of the flexible DC offshore station AC voltage through control, and does not consider the influence of the electrical quantity impact on the flexible DC converter valve and other devices in the starting process, and reduces the reliability of the offshore wind power through flexible DC grid connection system. Compared with the traditional starting control method, the application realizes smooth starting of the system and improves the reliability of the offshore wind power through flexible DC grid connection system by coordinating the control of the offshore converter station and the land converter station, and using the preset DC oscillation suppression model to suppress the DC oscillation of the land converter station when the land converter station is unlocked. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor.

[0046] Figure 1 A step flow chart of a starting control method of an offshore wind power through flexible DC grid connection system provided by the embodiment one of the present application;

[0047] Figure 2 A double-ended offshore wind power through flexible DC grid connection system topology structure schematic diagram provided by the embodiment one of the present application;

[0048] Figure 3 A flexible DC converter valve topology structure schematic diagram provided by the embodiment one of the present application;

[0049] Figure 4 A step flow chart of a starting control method of an offshore wind power through flexible DC grid connection system provided by the embodiment two of the present application;

[0050] Figure 5 A starting first stage schematic diagram of an offshore wind power through flexible DC grid connection system provided by the embodiment two of the present application;

[0051] Figure 6 A starting second stage schematic diagram of an offshore wind power through flexible DC grid connection system provided by the embodiment two of the present application;

[0052] Figure 7 The third stage diagram of starting of the offshore wind power through the flexible DC grid-connected system is provided for the second embodiment of the present application.

[0053] Figure 8 The structure diagram of the DC oscillation suppression model is provided for the second embodiment of the present application.

[0054] Figure 9 The fourth stage diagram of starting of the offshore wind power through the flexible DC grid-connected system is provided for the second embodiment of the present application.

[0055] Figure 10 The structure block diagram of the starting control device of the offshore wind power through the flexible DC grid-connected system is provided for the third embodiment of the present application.

[0056] Figure 11 The structure block diagram of the electronic device is provided for the fourth embodiment of the present application. DETAILED DESCRIPTION

[0057] The offshore wind power through the flexible DC grid-connected system starting control method and device are provided in the embodiments of the present application, which are used for solving the technical problem that the existing offshore wind power through the flexible DC grid-connected system starting control method only considers how to complete the establishment of the flexible DC offshore station AC voltage through control, and does not consider the influence of the electrical quantity impact on the flexible DC converter valve and other devices in the starting process, thereby reducing the reliability of the offshore wind power through the flexible DC grid-connected system.

[0058] In order to make the technical features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the following described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0059] Please refer to Figure 1 , Figure 1 The step flow chart of the offshore wind power through the flexible DC grid-connected system starting control method is provided for the first embodiment of the present application.

[0060] The offshore wind power through the flexible DC grid-connected system starting control method is provided in the present application, which is applied to the offshore wind power through the flexible DC grid-connected system, the offshore wind power through the flexible DC grid-connected system including the land converter station and the offshore converter station, and comprising:

[0061] It is worth mentioning that, please refer to Figure 2As shown, there is a great difference in DC control function between the offshore wind power through the flexible DC grid-connected system and the traditional two-end networking flexible DC, especially in the DC starting process, the stable AC voltage amplitude and frequency need to be provided for the offshore wind farm to complete the start of the offshore wind farm. Figure 3 As shown, the existing start control of the offshore wind power through the flexible DC grid-connected system often only considers how to control the establishment of the AC voltage of the offshore station of the flexible DC, and does not consider how to reduce the threat of the electrical quantity impact of the unlocking process to the flexible DC converter valve and other devices in the whole starting process, so as to realize the smooth start of the flexible DC two-end converter station.

[0062] Step 101, real-time acquisition of the voltage of each onshore sub-module and the voltage of each offshore sub-module in the offshore wind power through the flexible DC grid-connected system, and uncontrolled charging of the offshore converter station and the onshore converter station;

[0063] In the embodiment of the present application, the onshore converter station is AC uncontrolled charged by the AC power grid connected through the onshore converter station, the offshore converter station is DC uncontrolled charged by the generated DC voltage, and the voltage of each onshore sub-module and the voltage of each offshore sub-module in the offshore wind power through the flexible DC grid-connected system are acquired in real time.

[0064] Step 102, judging whether the voltage of each onshore sub-module and the voltage of each offshore sub-module is greater than or equal to the corresponding first stage voltage value;

[0065] The onshore sub-module voltage refers to the capacitor voltage value of the onshore converter valve sub-module.

[0066] The offshore sub-module voltage refers to the capacitor voltage value of the offshore converter valve sub-module.

[0067] In the embodiment of the present application, it is judged whether the voltage of each onshore sub-module and the voltage of each offshore sub-module reaches the corresponding first stage voltage value.

[0068] It should be noted that the first stage voltage value refers to the maximum capacitor voltage of each onshore sub-module and each offshore sub-module in the first stage of starting of the offshore wind power through the flexible DC grid-connected system.

[0069] Step 103, when the voltage of each onshore sub-module and the voltage of each offshore sub-module is greater than or equal to the corresponding first stage voltage value, the offshore converter station and the onshore converter station are controlled charged;

[0070] In the embodiment of the present application, if the voltage of each onshore sub-module and the voltage of each offshore sub-module reaches the first stage voltage value, the offshore converter station and the onshore converter station are controlled charged based on the capacitor voltage equalization strategy of the converter valve.

[0071] It should be noted that 1, when the converter station is a land converter station, the capacitor voltage sharing strategy is: turn on (sqrt(2)*Uac / Uc2_rate) sub-modules for charging, wherein Uac is the AC line voltage of the AC side of the land station, and Uc2_rate is the corresponding second stage voltage value of the land sub-module voltage.

[0072] 2, when the converter station is not a sea converter station, the capacitor voltage sharing strategy is: keep the number of sub-modules on each bridge arm on and off as N / 2, and a total of N sub-modules are turned on in the charging circuit, wherein N is the number of sub-modules of the land converter station.

[0073] Step 104, judge whether each land sub-module voltage and each sea sub-module voltage is greater than or equal to the corresponding second stage voltage value;

[0074] In the embodiment of the application, whether each land sub-module voltage and each sea sub-module voltage reaches the corresponding second stage voltage value is judged.

[0075] It should be noted that the second stage voltage value refers to the maximum capacitor voltage of each land sub-module and each sea sub-module in the second stage of starting the sea wind power through the flexible DC grid-connected system.

[0076] Step 105, when each land sub-module voltage and each sea sub-module voltage is greater than or equal to the corresponding second stage voltage value, then based on each sea sub-module voltage and a preset DC oscillation suppression model, the sea converter station and the land converter station are started.

[0077] In the embodiment of the application, when each land sub-module voltage and each sea sub-module voltage is greater than or equal to the corresponding second stage voltage value, then based on the preset DC oscillation suppression model, the land converter station is unlocked, and the sea converter station is kept locked, and the DC controllable charging of the converter valve of the sea converter station is continued. Until each sea sub-module voltage reaches the preset third stage threshold, the sea converter station is unlocked.

[0078] It should be noted that after unlocking the land converter station, the DC oscillation suppression model is turned on to suppress the DC oscillation of the land converter station, so as to reduce the impact current at the unlocking moment.

[0079] In the embodiment of the present application, firstly, the offshore converter station and the onshore converter station are uncontrolled charging, when each onshore sub-module voltage and each offshore sub-module voltage are greater than or equal to the corresponding first stage voltage value, then the offshore converter station and the onshore converter station are controlled charging, when each onshore sub-module voltage and each offshore sub-module voltage are greater than or equal to the corresponding second stage voltage value, then based on each offshore sub-module voltage and the preset DC oscillation suppression model, the offshore converter station and the onshore converter station are started, which overcomes the existing offshore wind power through flexible DC grid connection system starting control method, only considers how to control the establishment of the flexible DC offshore station AC voltage, and does not consider the influence of the electrical quantity impact on the flexible DC converter valve and other devices in the starting process, which reduces the reliability of the offshore wind power through flexible DC grid connection system. Compared with the traditional starting control method, the offshore converter station and the onshore converter station are coordinated and controlled, and when the onshore converter station is unlocked, the onshore converter station is subjected to DC oscillation suppression by using the preset DC oscillation suppression model, so that the system is started smoothly, and the reliability of the offshore wind power through flexible DC grid connection system is improved.

[0080] Please refer to Figure 4 , Figure 4 The step flow chart of the offshore wind power through flexible DC grid connection system starting control method provided for the second embodiment of the present application.

[0081] The offshore wind power through flexible DC grid connection system starting control method provided by the present application is applied to the offshore wind power through flexible DC grid connection system, which includes an onshore converter station and an offshore converter station, and includes the following steps.

[0082] Step 201, real-time acquisition of each onshore sub-module voltage and each offshore sub-module voltage in the offshore wind power through flexible DC grid connection system, and uncontrolled charging of the offshore converter station and the onshore converter station;

[0083] In the embodiment of the present application, the real-time acquisition of each onshore sub-module voltage and each offshore sub-module voltage in the offshore wind power through flexible DC grid connection system, and the uncontrolled charging of the onshore converter station and the onshore converter station are performed by using the AC power grid connected to the onshore converter station to perform AC uncontrolled charging on N sub-modules of the onshore converter valve of the onshore converter station, to generate a DC voltage, and by using the DC voltage to perform DC uncontrolled charging on 2N sub-modules of the offshore converter valve of the offshore converter station.

[0084] It should be noted that when the offshore converter station and the onshore converter station are uncontrolled charging, the offshore converter station and the onshore converter station are both locked.

[0085] It should be noted that the offshore wind power through the flexible DC grid-connected system includes the onshore converter station and the offshore converter station, the onshore converter station includes the onshore converter valve, and the onshore converter valve includes a plurality of onshore sub-modules. The offshore converter station includes the offshore converter valve, and the offshore converter valve includes a plurality of offshore sub-modules.

[0086] It should be noted that, referring to Figure 5 As shown in the figure, taking the onshore converter station AB phase charging loop as an example, the diode of the N sub-modules through the A-phase upper arm charges the capacitor of the N sub-modules of the B-phase upper arm, and the voltage of each sub-module capacitor is charged to √2*Uac / N. Similarly, through the charging loop of the other phase, the sub-modules of the upper and lower arms of the ABC three-phase can be charged respectively, and each is charged to √2*Uac / N, and the DC side voltage also reaches the maximum √2*Uac. For the offshore converter valve, the 2N sub-modules of the three-phase upper and lower arms are unidirectionally charged through the DC side voltage √2*Uac, until the voltage of each sub-module capacitor reaches the maximum √2*Uac / 2N.

[0087] Step 202, judge whether each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first stage voltage value;

[0088] In the embodiment of the application, it is judged whether each onshore sub-module voltage is greater than or equal to the corresponding first stage voltage value (i.e. √2*Uac / N), and whether each offshore sub-module voltage is greater than or equal to the corresponding first stage voltage value (i.e. √2*Uac / 2N).

[0089] Step 203, when each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first stage voltage value, the bypass switch of the starting loop in the onshore converter station is closed, and the onshore sub-modules in the onshore converter station are charged based on the preset onshore input quantity;

[0090] In the embodiment of the application, when each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first stage voltage value, the bypass switch of the starting loop in the onshore converter station is closed, and the onshore sub-modules of the preset onshore input quantity are charged in turn.

[0091] It should be noted that the onshore input quantity specific configuration process is:

[0092] The DC side voltage of the onshore converter station at the current time is obtained, and the onshore input quantity function is input according to the DC side voltage and the corresponding second stage voltage value of the onshore sub-module voltage, to obtain the onshore input quantity;

[0093] The onshore input quantity function is specifically:

[0094] ;

[0095] wherein, is the onshore input quantity, is the DC side voltage, is the corresponding second stage voltage value of the onshore sub-module voltage.

[0096] Further comprising:

[0097] A1, when any onshore sub-module voltage or any offshore sub-module voltage is less than the corresponding first stage voltage value, then jump to execute the step of uncontrolled charging of the offshore converter station and the onshore converter station until each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first stage voltage value.

[0098] In the embodiment of the present application, when any onshore sub-module voltage or any offshore sub-module voltage is less than the corresponding first stage voltage value, then jump to execute step 201.

[0099] Step 204, based on the preset offshore input quantity, charge the offshore bridge arm in the offshore converter station.

[0100] In the embodiment of the present application, based on the preset offshore input quantity, the offshore bridge arm in the offshore converter station is charged.

[0101] It should be noted that the number of offshore sub-modules input into the upper bridge arm and the lower bridge arm of each bridge arm of the offshore converter valve in the offshore converter station is respectively the preset offshore input quantity, and N offshore sub-modules are input into the charging circuit for each bridge arm.

[0102] It should be noted that the specific configuration process of the offshore input quantity is as follows:

[0103] Obtain the number of offshore sub-modules, and perform ratio processing on the number of offshore sub-modules (i.e. 2N) and the preset input coefficient (i.e. 4) to obtain the offshore input quantity.

[0104] Step 205, judge whether each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding second stage voltage value;

[0105] In the embodiment of the present application, whether each onshore sub-module voltage is greater than or equal to the corresponding second stage voltage value (i.e. ) is judged. Whether each offshore sub-module voltage is greater than or equal to the corresponding second stage voltage value (i.e. √2*Uac / N) is judged.

[0106] It should be noted that reference is made to Figure 6As shown, when each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first stage voltage value, the onshore converter valve enters an AC controllable charging mode by closing the bypass breaker of the onshore converter station starting loop: by turning on (sqrt(2)*Uac / Uc2_rate) modules in turn, the target is to charge each sub-module of the onshore converter valve to the corresponding second stage voltage value (i.e. Uc2_rate); at this time, the DC side voltage remains unchanged at sqrt(2)*Uac, and the offshore converter valve enters a DC controllable charging mode: by keeping the number of upper and lower arms of each bridge arm as N / 2, a total of N offshore sub-modules are turned on in each bridge arm to enter the charging loop, and the voltage of each offshore sub-module capacitor is charged to sqrt(2)*Uac / N.

[0107] Step 206, when each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding second stage voltage value, then based on each offshore sub-module voltage and a preset DC oscillation suppression model, the offshore converter station and the onshore converter station are started.

[0108] Further, it also includes:

[0109] A2, when any onshore sub-module voltage or any offshore sub-module voltage is less than the corresponding second stage voltage value, then jump to execute the step of controllable charging of the offshore converter station and the onshore converter station until each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding second stage voltage value.

[0110] In the embodiment of the application, when any onshore sub-module voltage or any offshore sub-module voltage is less than the corresponding second stage voltage value, then jump to execute step 203.

[0111] It should be noted that when the offshore converter station and the onshore converter station are controllably charged, the offshore converter station and the onshore converter station are both locked.

[0112] Further, step 206 includes the following sub-steps:

[0113] S11, unlocking the onshore converter station and acquiring the DC side DC current of the onshore converter station in real time;

[0114] In the embodiment of the application, the onshore converter station is manually unlocked, and the DC side DC current of the onshore converter station is acquired in real time.

[0115] S12, inputting the DC side DC current into a preset DC oscillation suppression model to obtain a DC voltage reference value, wherein the DC oscillation suppression model includes a difference operator, a filter and a damping coefficient device connected in sequence;

[0116] In the embodiment of the present application, the DC oscillation analysis is performed on the DC side DC current by using the preset DC oscillation suppression model to obtain a DC voltage reference value, wherein the DC oscillation suppression model comprises a difference operator, a filter and a damping coefficient generator connected in sequence.

[0117] It should be noted that, as shown in Figure 8 The difference between the DC current reference value and the DC side DC current is processed by the difference operator to obtain a first difference, the specific harmonic component in the first difference is extracted by the filter link, and multiplied by the damping coefficient to simulate the virtual resistance in series on the DC loop to generate an additional DC voltage reference value Udcref1 superimposed on the modulation wave Udcref generated by the original DC voltage control, thereby realizing the DC oscillation suppression of the land converter station.

[0118] S13, using the DC voltage reference value to perform DC oscillation suppression operation on the land converter station, and based on the preset first ramp rate, gradually increasing the DC voltage of the land converter station to the preset DC rated voltage;

[0119] In the embodiment of the present application, as shown in Figure 7 The DC voltage reference value Udcref1 is superimposed on the modulation wave Udcref generated by the original DC voltage control to perform DC oscillation suppression operation on the land converter station, and the DC voltage of the land converter station is gradually increased to the preset DC rated voltage according to the preset first ramp rate.

[0120] It should be noted that, as shown in Figure 7 During the DC oscillation suppression operation on the land converter station, based on the preset first ramp rate, the DC voltage of the land converter station is gradually increased to the preset DC rated voltage (i.e. the third phase). The offshore converter valve still performs DC controllable charging, and the upper and lower bridge arms are respectively put into N / 2 sub-modules, which is equivalent to the equivalent capacitance of the DC side remains unchanged, to cope with the influence of the step rise of the DC voltage of the land converter station on the offshore converter station at the unlocking moment of the land converter station. After that, the offshore sub-module capacitor voltage gradually reaches the rated value Uc1_rate=Udc2_rate / N as the DC voltage rises to the third phase threshold value (i.e. Uc1_rate), and the entire charging process is basically impact-free, realizing smooth charging.

[0121] S14, judging whether each offshore sub-module voltage is greater than or equal to the preset third phase threshold value,

[0122] In the embodiment of the present application, it is judged whether each offshore sub-module voltage reaches the preset third phase threshold value.

[0123] S15, if each offshore sub-module voltage is greater than or equal to the third stage threshold value, then the offshore converter station is unlocked, and the offshore converter station is unlocked based on a preset second ramping rate;

[0124] Further, S15 includes the following sub-steps:

[0125] S151, each offshore sub-module in the offshore converter station is switched on or off by a preset offshore station control target model;

[0126] In the embodiment of the present application, referring to Figure 9 As shown, when each offshore sub-module voltage reaches the third stage threshold value (i.e. Uc1_rate), the fourth stage is started, the instruction of unlocking the offshore station is opened, the offshore converter station unlocking instruction is manually issued, and the modulation wave generated by the preset offshore station control target model is used to switch on or off each offshore sub-module.

[0127] S152, based on the preset second ramping rate, the AC voltage of the offshore converter station is gradually increased to the preset AC rated voltage.

[0128] In the embodiment of the present application, the AC voltage of the offshore converter station is gradually increased from 0kv to the preset AC rated voltage according to the preset second ramping rate.

[0129] S16, if any offshore sub-module voltage is less than the third stage threshold value, then the step of controllable charging of the offshore converter station is performed until each offshore sub-module voltage is greater than or equal to the third stage threshold value.

[0130] In the embodiment of the present application, when any offshore sub-module voltage is less than the third stage threshold value, the step of controllable charging of the offshore converter station is performed until each offshore sub-module voltage reaches the third stage threshold value.

[0131] It is worth mentioning that the voltage of each stage of the onshore sub-module and the offshore sub-module is shown in Table 1.

[0132] Table 1

[0133]

[0134] In the embodiment of the present application, firstly, the offshore converter station and the onshore converter station are uncontrolled charging, when each onshore sub-module voltage and each offshore sub-module voltage are greater than or equal to the corresponding first stage voltage value, then the offshore converter station and the onshore converter station are controlled charging, when each onshore sub-module voltage and each offshore sub-module voltage are greater than or equal to the corresponding second stage voltage value, then based on each offshore sub-module voltage and the preset DC oscillation suppression model, the offshore converter station and the onshore converter station are started, which overcomes the existing offshore wind power through flexible DC grid connection system starting control method, only considers how to control the establishment of the flexible DC offshore station AC voltage, and does not consider the influence of the electrical quantity impact on the flexible DC converter valve and other devices in the starting process, which reduces the reliability of the offshore wind power through flexible DC grid connection system. Compared with the traditional starting control method, the offshore converter station and the onshore converter station are coordinated and controlled, and when the onshore converter station is unlocked, the onshore converter station is subjected to DC oscillation suppression by using the preset DC oscillation suppression model, so that the system is started smoothly, and the reliability of the offshore wind power through flexible DC grid connection system is improved.

[0135] Please refer to Figure 10 , Figure 10 The structure block diagram of the offshore wind power through flexible DC grid connection system starting control device provided in the third embodiment of the present application.

[0136] The offshore wind power through flexible DC grid connection system starting control device provided by the present application is applied to the offshore wind power through flexible DC grid connection system, which includes an onshore converter station and an offshore converter station, and comprises:

[0137] The first starting module 301 is used for acquiring each onshore sub-module voltage and each offshore sub-module voltage in the offshore wind power through flexible DC grid connection system in real time, and performing uncontrolled charging on the offshore converter station and the onshore converter station.

[0138] The first analysis module 302 is used for judging whether each onshore sub-module voltage and each offshore sub-module voltage are greater than or equal to the corresponding first stage voltage value.

[0139] The second starting module 303 is used for performing controlled charging on the offshore converter station and the onshore converter station when each onshore sub-module voltage and each offshore sub-module voltage are greater than or equal to the corresponding first stage voltage value.

[0140] The second analysis module 304 is used for judging whether each onshore sub-module voltage and each offshore sub-module voltage are greater than or equal to the corresponding second stage voltage value.

[0141] The unlocking module 305 is configured to, when each of the onshore sub-module voltage and each of the offshore sub-module voltage is greater than or equal to the corresponding second stage voltage value, start the offshore converter station and the onshore converter station based on each of the offshore sub-module voltage and a preset DC oscillation suppression model.

[0142] Further, the second starting module 303 comprises:

[0143] The onshore charging sub-module is configured to control the bypass breaker of the starting loop in the onshore converter station to be closed, and charge the onshore sub-module in the onshore converter station based on a preset onshore input quantity;

[0144] The offshore charging sub-module is configured to charge the offshore bridge arm in the offshore converter station based on a preset offshore input quantity.

[0145] Further, the unlocking module 305 comprises:

[0146] The onshore unlocking sub-module is configured to unlock the onshore converter station and acquire the DC side DC current of the onshore converter station in real time;

[0147] The DC oscillation suppression sub-module is configured to input the DC side DC current into a preset DC oscillation suppression model to obtain a DC voltage reference value, wherein the DC oscillation suppression model comprises a difference operator, a filter and a damping coefficient device connected in sequence;

[0148] The first regulation sub-module is configured to perform DC oscillation suppression on the onshore converter station by using the DC voltage reference value, and control the DC voltage of the onshore converter station to gradually increase to a preset DC rated voltage based on a preset first ramping rate;

[0149] The first analysis sub-module is configured to determine whether each of the offshore sub-module voltage is greater than or equal to a preset third stage threshold value,

[0150] The second regulation sub-module is configured to, if each of the offshore sub-module voltage is greater than or equal to the third stage threshold value, unlock the offshore converter station and perform unlocking operation on the offshore converter station based on a preset second ramping rate;

[0151] The jump sub-module is configured to, if any of the offshore sub-module voltage is less than the third stage threshold value, perform the controllable charging step on the offshore converter station until each of the offshore sub-module voltage is greater than or equal to the third stage threshold value.

[0152] Further, the second regulation sub-module comprises:

[0153] The first regulation unit is configured to perform switching control on each of the offshore sub-module in the offshore converter station by using a preset offshore station control target model;

[0154] The second regulating unit is configured to control the AC voltage of the offshore converter station to gradually increase to the preset AC rated voltage based on a preset second climbing rate.

[0155] Further, the method further comprises:

[0156] The first jump module is configured to jump to perform the step of uncontrolled charging of the offshore converter station and the onshore converter station when any onshore sub-module voltage or any offshore sub-module voltage is less than the corresponding first-stage voltage value, until each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding first-stage voltage value.

[0157] Further, the method further comprises:

[0158] The second jump module is configured to jump to perform the step of controlled charging of the offshore converter station and the onshore converter station when any onshore sub-module voltage or any offshore sub-module voltage is less than the corresponding second-stage voltage value, until each onshore sub-module voltage and each offshore sub-module voltage is greater than or equal to the corresponding second-stage voltage value.

[0159] Further, the onshore input quantity configuration process is specifically configured as:

[0160] The DC side voltage of the onshore converter station at the current time is obtained, and the onshore input quantity function is inputted with the DC side voltage and the corresponding second-stage voltage value of the onshore sub-module voltage, to obtain the onshore input quantity.

[0161] The onshore input quantity function is specifically configured as:

[0162] ;

[0163] Wherein, the onshore input quantity, the DC side voltage, the corresponding second-stage voltage value of the onshore sub-module voltage;

[0164] The offshore input quantity configuration process is specifically configured as:

[0165] The offshore sub-module quantity is obtained, and the offshore input quantity is obtained by ratio processing of the offshore sub-module quantity and the preset input coefficient.

[0166] Please refer to Figure 11 , Figure 11 is a structural block diagram of an electronic device provided by the fourth embodiment of the present application.

[0167] The electronic device of the embodiment of the application comprises a memory 401 and a processor 402, the memory 401 stores a computer program, and the computer program is executed by the processor 402 to enable the processor 402 to execute the offshore wind power flexible DC grid connection system starting control method of any of the above embodiments.

[0168] The memory 401 can be an electronic memory such as a flash memory, an EEPROM (electrically erasable programmable read-only memory), an EPROM, a hard disk or a ROM. The memory 401 has a storage space 403 for program codes 413 for executing any of the method steps described above. For example, the storage space 403 for program codes can comprise individual program codes 413 for implementing respective steps in the above methods. These program codes can be read from or written to one or more computer program products. These computer program products comprise program code carriers such as hard disks, compact disks (CDs), memory cards or floppy disks. The program codes can be compressed in a suitable form, for example. These codes, when executed by a computing processing device, cause the computing processing device to perform the respective steps in the methods described above.

[0169] The fifth embodiment of the application also provides a computer-readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the offshore wind power flexible DC grid connection system starting control method of any of the above embodiments.

[0170] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0171] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed units can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0172] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, i.e., may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0173] In addition, each functional unit in each embodiment of the application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0174] If the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the application or the part of the prior art that essentially contributes or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method of each embodiment of the application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0175] The above embodiments are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A method for starting and controlling offshore wind power via a flexible DC grid-connected system, characterized in that, This is applied to a flexible DC grid-connected system for offshore wind power, which includes an onshore converter station and an offshore converter station, comprising: The voltage of each onshore submodule and each offshore submodule in the offshore wind power flexible DC grid connection system is acquired in real time, and uncontrolled charging is performed on the offshore converter station and the onshore converter station. Determine whether the voltage of each land submodule and the voltage of each marine submodule are greater than or equal to the corresponding first-stage voltage value; When the voltage of each of the onshore submodules and the voltage of each of the offshore submodules are greater than or equal to the corresponding first-stage voltage value, the offshore converter station and the onshore converter station are controlled to be charged. Determine whether the voltage of each land submodule and the voltage of each marine submodule are greater than or equal to the corresponding second-stage voltage value; When the voltage of each of the onshore submodules and the voltage of each of the offshore submodules are greater than or equal to the corresponding second-stage voltage value, the onshore converter station is unlocked and the DC current on the DC side of the onshore converter station is acquired in real time. The DC current on the DC side is input into a preset DC oscillation suppression model to obtain a DC voltage reference value. The DC oscillation suppression model includes a difference calculator, a filter, and a damping coefficient connected in sequence. The DC voltage reference value is used to perform DC oscillation suppression operation on the onshore converter station, and based on the preset first ramp rate, the DC voltage of the onshore converter station is controlled to gradually increase to the preset rated DC voltage. Determine whether the voltage of each of the aforementioned marine sub-modules is greater than or equal to a preset third-stage threshold. If the voltage of each of the marine sub-modules is greater than or equal to the third stage threshold, the marine converter station is unlocked, and the marine converter station is unlocked based on the preset second climb rate. If the voltage of any of the offshore submodules is less than the third stage threshold, then the offshore converter station is subjected to a controlled charging step until the voltage of each of the offshore submodules is greater than or equal to the third stage threshold.

2. The method for starting and controlling offshore wind power via a flexible DC grid-connected system according to claim 1, characterized in that, The step of controllably charging the offshore converter station and the onshore converter station includes: Control the closing of the bypass switch of the start-up circuit in the onshore converter station, and charge the onshore sub-modules in the onshore converter station based on the preset onshore commissioning quantity; Based on the preset number of offshore deployments, the offshore bridge arm of the offshore converter station is charged.

3. The method for starting and controlling offshore wind power via a flexible DC grid-connected system according to claim 1, characterized in that, The step of unlocking the offshore converter station based on a preset second climb rate includes: The switching control of each marine sub-module in the marine converter station is performed using a preset marine station control target model. Based on a preset second climb rate, the AC voltage of the offshore converter station is controlled to gradually increase to a preset AC rated voltage.

4. The method for starting and controlling offshore wind power via a flexible DC grid-connected system according to claim 1, characterized in that, Also includes: When the voltage of any of the onshore submodules or the voltage of any of the offshore submodules is less than the corresponding first-stage voltage value, the process jumps to the step of uncontrolled charging of the offshore converter station and the onshore converter station until the voltage of each of the onshore submodules and the voltage of each of the offshore submodules are greater than or equal to the corresponding first-stage voltage value.

5. The method for starting and controlling offshore wind power via a flexible DC grid-connected system according to claim 1, characterized in that, Also includes: When the voltage of any of the onshore submodules or the voltage of any of the offshore submodules is less than the corresponding second-stage voltage value, the process jumps to the step of controlling the charging of the offshore converter station and the onshore converter station until the voltage of each onshore submodule and the voltage of each offshore submodule are greater than or equal to the corresponding second-stage voltage value.

6. The method for starting and controlling offshore wind power via a flexible DC grid-connected system according to claim 2, characterized in that, The specific configuration process for the land-based deployment quantity is as follows: Obtain the DC-side voltage of the onshore converter station at the current moment, and input the second-stage voltage value corresponding to the DC-side voltage and the onshore submodule voltage into a preset onshore input quantity function to obtain the onshore input quantity; The specific function for the quantity of land-based inputs is as follows: ； in, For the number deployed on land, DC side voltage This is the second-stage voltage value corresponding to the voltage of the land-based submodule; The specific configuration process for the quantity deployed at sea is as follows: The number of marine sub-modules is obtained, and the ratio of the number of marine sub-modules to a preset input coefficient is processed to obtain the marine input quantity.

7. A start-up control device for offshore wind power via a flexible DC grid-connected system, used to implement the start-up control method for offshore wind power via a flexible DC grid-connected system as described in any one of claims 1-6, characterized in that, This is applied to a flexible DC grid-connected system for offshore wind power, which includes an onshore converter station and an offshore converter station, comprising: The first startup module is used to acquire the voltage of each onshore submodule and each offshore submodule in the offshore wind power flexible DC grid connection system in real time, and to perform uncontrolled charging on the offshore converter station and the onshore converter station. The first analysis module is used to determine whether the voltage of each land submodule and the voltage of each marine submodule are greater than or equal to the corresponding first-stage voltage value. The second startup module is used to controllably charge the offshore converter station and the onshore converter station when the voltage of each onshore submodule and the voltage of each offshore submodule are both greater than or equal to the corresponding first-stage voltage value. The second analysis module is used to determine whether the voltage of each land submodule and the voltage of each marine submodule are greater than or equal to the corresponding second-stage voltage value. The unlocking module is used to start the offshore converter station and the onshore converter station based on the voltage of each offshore submodule and a preset DC oscillation suppression model when the voltage of each onshore submodule and the voltage of each offshore submodule are both greater than or equal to the corresponding second-stage voltage value.

8. An electronic device, characterized in that, The system includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the steps of the offshore wind power start-up control method via a flexible DC grid connection as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the offshore wind power start-up control method via a flexible DC grid-connected system as described in any one of claims 1-6.

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