Pq tracking feedback control strategy method based on offshore wind power frequency deviation damper

Abstract

The application discloses a PQ tracking feedback control strategy method based on a marine wind power frequency deviation damper, which comprises the following steps: building a marine wind power flexible high-voltage alternating current transmission system on a PSCAD power system simulation software, wherein the system comprises a machine-side converter connected with a marine wind turbine, a grid-side converter, a step-up transformer and a transmission line, the machine-side converter is connected with the step-up transformer through the grid-side converter, and the step-up transformer is connected with a large-capacity power source through the transmission line in sequence; the transmission line comprises a submarine cable and an overhead line; the control strategy comprises the control of the machine-side converter and the grid-side converter, the machine-side converter adopts voltage control on the direct current side of the converter and reactive power control on the alternating current side of the converter; the grid-side converter adopts a reactive power and alternating current voltage control mode; and the method effectively suppresses power oscillation in an alternating current power grid and improves the reliability of marine wind power transmission.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power grid connection technology, and in particular to a PQ tracking feedback control strategy method based on an offshore wind power frequency deviation damper. Background Technology

[0002] With the continuous expansion of the power system and the ongoing development of new energy technologies, the installed capacity of systems represented by wind power is also constantly increasing, continuously connecting with the main grid. In the current hot research field, offshore wind power is increasingly becoming the future direction of new energy development. Because offshore wind farms are far away, they have less impact on residents' production and life, and offshore wind resources are abundant. Therefore, the scale of newly built offshore wind farms is also continuously increasing.

[0003] At present, the grid-connected areas of wind farms in my country are characterized by weak grid structure and long-distance transmission. Especially under the weak grid structure, if a certain degree of fault occurs, the interaction between the large wind turbines and the main grid and power electronic equipment such as converters may lead to low-frequency oscillations or subsynchronous oscillations, thereby affecting the stability of system operation.

[0004] Since most wind farms are connected to the main grid via high-voltage transmission, the inertia provided by the wind turbines to the grid system during operation is extremely small, which weakens the overall stability of the system and increases the risk of various oscillations. As a result, the system has poor stability during power transmission.

[0005] Therefore, this application provides a PQ tracking feedback control strategy based on offshore wind power frequency deviation dampers. By controlling the turbine-side converter and the grid-side converter, it is possible to achieve fast and real-time tracking feedback control of active and reactive power. In addition, by utilizing flexible transmission technology, the control has a large degree of freedom and rapid feedback adjustment, which can quickly suppress power oscillations in offshore wind power and improve the stability of system operation. Summary of the Invention

[0006] The technical problem this invention aims to solve is the issue of power oscillations occurring during power transmission due to equipment failures after existing offshore wind power grid connection, which affects the stability of system operation. This invention provides a PQ tracking feedback control strategy based on offshore wind power frequency deviation dampers. By controlling the turbine-side converter and the grid-side converter, the system can achieve rapid and real-time tracking feedback control of active and reactive power. Furthermore, by utilizing flexible transmission technology, which offers high control freedom and rapid feedback adjustment, it can quickly suppress power oscillations in offshore wind power and improve system operational stability.

[0007] The technical solution adopted by this invention to solve its technical problem is: a PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper, including building an offshore wind power flexible high-voltage AC transmission system on PSCAD power system simulation software. The system includes a turbine-side converter, a grid-side converter, a step-up transformer and transmission lines connected to the offshore wind turbine. The turbine-side converter is connected to the step-up transformer through the grid-side converter. The step-up transformer is connected to a large-capacity power source through the transmission lines.

[0008] Control strategies are set on the machine-side converter and the grid-side converter;

[0009] The control strategy for the machine-side converter includes setting voltage control on the DC side of the machine-side converter and setting reactive power control on the AC side of the machine-side converter.

[0010] The DC side of the machine-side converter is equipped with voltage control to achieve dynamic power balance of the system;

[0011] The AC side of the converter is equipped with reactive power control to meet the reactive power requirements of offshore wind farms and to output the maximum wind power.

[0012] The control strategy for the grid-side converter adopts a reactive power and AC voltage control method, specifically including the control of the frequency, reactive power, DC voltage, and current of the grid-side converter. This control method includes the following steps:

[0013] Step 1. Obtain the three-phase voltage u at the bus node through the grid-side converter. abc Three-phase current i abc and DC voltage u dc The three-phase voltage u abc As input, the AC grid frequency ω at the bus node is obtained from the PLL phase-locked loop, and then the three-phase voltage u is used as input. abc Three-phase current i abc As input, the real-time reactive power Q is obtained through the instantaneous power calculator;

[0014] Step 2. Obtain the reactive power reference value Q using the AC grid frequency ω and the rated angular frequency ω0 obtained in Step 1. ref The AC grid frequency ω and the rated angular frequency ω0 are used as inputs to the damper to obtain the system's DC reference voltage u. dcref ;

[0015] Step 3. Utilize the DC voltage u from Step 1 dc The DC reference voltage u obtained in step 2 dcref As the input to PI controller one, the AC current reference value i in the d-axis is obtained. drefThe real-time reactive power Q obtained in step 1 is compared with the reactive power reference value Q obtained in step 2. ref As the input to PI controller two, the AC current reference value i in the q-axis is obtained. qref ;

[0016] Step 4. Obtain the phase angle θ from the PLL in Step 1. PLL With three-phase current i abc As input to the dq transform, the currents i in the d and q axes are output respectively. d and i q ;

[0017] Step 5. The d-axis AC current reference value i obtained in Steps 3 and 4 above is used as the reference value. dref d-axis current i d Reference value of AC current i along the q-axis qref q-axis current i q These are respectively used as inputs to PI controller three and PI controller four, and the outputs of PI controller three and PI controller four are jointly input into SPWM, which is then modulated to obtain a drive signal S. abc .

[0018] Furthermore, in step 1, the PLL phase-locked loop converts the three-phase voltage u abc As input, obtain the AC power grid frequency ω and phase angle θ. PLL ;

[0019] Specifically, the three-phase voltage u at the busbar in the abc coordinate system is... abc Transformed into d-axis voltage v in dq coordinate system d and q-axis voltage v q Then, using the q-axis voltage v q With q-axis reference voltage v qref H, as the transfer function of the phase-locked loop PI regulator PLL (s) as input, obtain the AC grid frequency ω and phase angle θ PLL .

[0020] Furthermore, the transfer function H PLL (s) The specific formula is as follows:

[0021]

[0022] Among them, K pPLL and K iPLL These represent the proportional and integral coefficients of the PI control in the phase-locked loop (PLL), respectively.

[0023] Furthermore, the grid-side converter can adjust the reactive power reference value Q. ref The change in Q adjusts the actual reactive power;

[0024] Among them, the reactive power reference value Q ref The actual reactive power Q is specifically expressed using the following formula:

[0025]

[0026]

[0027] Among them, K p K i These represent the gain of the PI controller; U α i α and U β i β These represent the grid voltage and current on the α-axis and β-axis, respectively.

[0028] Furthermore, the DC reference voltage u dcref The input to the damper is obtained by using the AC grid frequency ω and the rated angular frequency ω0 as inputs, specifically using the following formula:

[0029]

[0030] in, This indicates a low-pass filter, and K represents the gain stage.

[0031] Furthermore, the grid-side converter can adjust according to the DC reference voltage u. dcref The change adjusts the actual DC voltage u dc This, in turn, generates corresponding changes in active power on the AC side, damping the change in AC grid frequency ω.

[0032] Furthermore, the control strategy of the grid-side converter reacts on a millisecond timescale.

[0033] Furthermore, an AC filter one is installed at the input end of the machine-side converter, and an AC filter two is installed at the output end of the grid-side converter.

[0034] The AC filter one and AC filter two are used to maintain the system bus voltage, eliminate harmonics, and compensate for reactive power.

[0035] Furthermore, the transmission line includes submarine cables and overhead lines. The submarine cables are laid on the seabed and are used for long-distance offshore high-voltage AC power transmission.

[0036] The elevated line is erected on land and is used to connect to the ground high-voltage transmission line grid.

[0037] Furthermore, the grounding layer of the elevated line is equipped with two ground wires.

[0038] Compared with the prior art, the beneficial effects of the present invention are: the PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper can achieve fast and real-time tracking feedback control of active and reactive power by controlling the turbine-side converter and the grid-side converter.

[0039] Flexible power transmission technology offers a high degree of control freedom and rapid feedback adjustment, enabling the quick suppression of power oscillations in offshore wind power and improving system stability. Attached Figure Description

[0040] Figure 1 A schematic diagram of the grid-side converter control strategy;

[0041] Figure 2 This is a schematic diagram of a PLL phase-locked loop control principle.

[0042] Figure 3 This is a schematic diagram of the control strategy for the machine-side converter.

[0043] Figure 4 A system block diagram built on a PSCAD model;

[0044] Figure 5 The simulation experiment analysis curves for the PSCAD model are shown below: Figure 5 a is the oscillation curve of a single-phase fault; Figure 5 b is a graph showing the duration of a single-phase ground fault for 0.2 seconds; Figure 5 c is the oscillation curve of a two-phase fault on the line.

[0045] In the diagram: 1. Offshore wind turbine; 2. Turbine-side converter; 3. Grid-side converter; 4. Step-up transformer; 5. Submarine cable; 6. Overhead line; 7. High-capacity power supply; 8. AC filter one; 9. AC filter two. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Please see Figure 1-4This invention provides a technical solution: a PQ tracking feedback control strategy method based on offshore wind power frequency deviation dampers, including building an offshore wind power flexible high-voltage AC transmission system on PSCAD power system simulation software. The system includes a turbine-side converter 2, a grid-side converter 3, a step-up transformer 4, and transmission lines connected to an offshore wind turbine 1. The turbine-side converter 2 is connected to the step-up transformer 4 through the grid-side converter 3. The step-up transformer 4 is connected to a large-capacity power source 7 through the transmission lines. In this embodiment, the offshore wind turbine 1 is a permanent magnet synchronous generator.

[0048] The transmission line includes a submarine cable 5 and an overhead line 6. The submarine cable 5 is laid on the seabed and is used for long-distance offshore high-voltage AC power transmission.

[0049] The elevated line 6 is erected on land and is used to connect to the ground high-voltage transmission line grid; wherein, the grounding layer of the elevated line 6 is equipped with two ground wires.

[0050] The input terminal of the machine-side converter 2 is equipped with an AC filter 8, and the output terminal of the grid-side converter 3 is equipped with an AC filter 9. The AC filter 8 and the AC filter 9 are used to maintain the bus voltage of the system, eliminate harmonics, and compensate for reactive power.

[0051] Control strategies are set on the machine-side converter 2 and the grid-side converter 3;

[0052] The control strategy of the machine-side converter 2 includes setting voltage control on the DC side of the machine-side converter and setting reactive power control on the AC side of the machine-side converter.

[0053] The DC side of the machine-side converter is equipped with voltage control to achieve dynamic power balance of the system;

[0054] The AC side of the turbine-side converter is equipped with reactive power control to meet the reactive power requirements of offshore wind farms and to output maximum wind power.

[0055] Please see Figure 3 On the DC side of the machine-side converter, through DC voltage u dc and DC voltage reference value u dcref As input, the AC current reference value i along the d-axis is obtained through the PI controller. dref The AC side of the machine-side converter is connected to the AC voltage u. s and AC voltage reference value u sref As input, the AC current reference value i along the q-axis is obtained via the PI controller. qref The reference values ​​of the AC current i along the d and q axes dref i qref Respectively related to the d-axis current i dand q-axis current i q The signals are used as inputs to PI controllers 7 and 8, and their outputs are also input to the SPWM, where they are modulated to obtain a drive signal.

[0056] The grid-side converter in this embodiment employs reactive power and AC voltage control, ensuring that the wind turbines will not easily disconnect from the grid during system faults. This avoids significant grid impact caused by wind turbines reconnecting to the grid after a fault. Regarding the system's reference voltage V... ref and reference frequency ω ref This can be derived from the following formula (1):

[0057]

[0058] Among them, V base ω represents the reference voltage output by the turbine unit. base Indicates the reference frequency. Indicates the active power reference value. P represents the reactive power reference value. s Q represents the real-time active power output of the system. s K represents the output reactive power. q and K p These represent the coefficients of the active power drop.

[0059] For the machine-side converter 2 and the grid-side converter 3, the active power P and reactive power Q of the converter can be obtained on the dq axis by the following formula (2) through the equal power transformation of the stationary coordinate system αβ:

[0060]

[0061] Among them, E d Represents the voltage on the d-axis, E q I represents the voltage on the q-axis. d Represents the current on the d-axis, I q This represents the current along the q-axis.

[0062] Please see Figure 1 The control strategy for the grid-side converter 3 adopts a reactive power and AC voltage control method, specifically including the control of the frequency, reactive power, DC voltage, and current of the grid-side converter 3. This control method includes the following steps:

[0063] Step 1. Obtain the three-phase voltage u at the bus node through the grid-side converter 3. abc Three-phase current i abc and DC voltage u dc The three-phase voltage u abcAs input, the AC grid frequency ω at the bus node is obtained from the PLL phase-locked loop, and then the three-phase voltage u is used as input. abc Three-phase current i abc As input, the real-time reactive power Q is obtained through the instantaneous power calculator;

[0064] Step 2. Obtain the reactive power reference value Q using the AC grid frequency ω and the rated angular frequency ω0 obtained in Step 1. ref The AC grid frequency ω and the rated angular frequency ω0 are used as inputs to the damper to obtain the system's DC reference voltage u. dcref ;

[0065] Step 3. Utilize the DC voltage u from Step 1 dc The DC reference voltage u obtained in step 2 dcref As the input to PI controller one, the AC current reference value i in the d-axis is obtained. dref The real-time reactive power Q obtained in step 1 is compared with the reactive power reference value Q obtained in step 2. ref As the input to PI controller two, the AC current reference value i in the q-axis is obtained. qref ;

[0066] Step 4. Obtain the phase angle θ from the PLL in Step 1. PLL With three-phase current i abc As input to the dq transform, the currents i in the d and q axes are output respectively. d and i q ;

[0067] Step 5. The d-axis AC current reference value i obtained in Steps 3 and 4 above is used as the reference value. dref d-axis current i d Reference value of AC current i along the q-axis qref q-axis current i q These are respectively used as inputs to PI controller three and PI controller four, and the outputs of PI controller three and PI controller four are jointly input into SPWM, which is then modulated to obtain a drive signal S. abc .

[0068] Please see Figure 2 In step 1, the PLL phase-locked loop converts the three-phase voltage u abc As input, obtain the AC power grid frequency ω and phase angle θ. PLL Specifically, the three-phase voltage u at the busbar in the abc coordinate system is... abc Transformed into d-axis voltage v in dq coordinate system d and q-axis voltage v q Then, using the q-axis voltage v q With q-axis reference voltage v qrefH, as the transfer function of the phase-locked loop PI regulator PLL (s) as input, obtain the AC grid frequency ω and phase angle θ PLL .

[0069] The transfer function H PLL (s) The specific formula is as follows:

[0070]

[0071] Among them, K pPLL and K iPLL These represent the proportional and integral coefficients of the PI control in the phase-locked loop (PLL), respectively.

[0072] In step 1 above, ω is used as the frequency of the AC power grid, which is detected by the system and used as a feedback signal. Together with the system's rated frequency ω0, this signal serves as the input to the damper. The output of the frequency control circuit is used as the reactive power reference value Q. ref Then, through the reactive power control loop, it is connected to the three-phase voltage u at the bus node. abc and three-phase current i abc The actual reactive power Q obtained by the instantaneous power calculator is used as the input of PI controller 2.

[0073] The grid-side converter 3 can adjust the reactive power reference value Q. ref The change adjusts the actual reactive power Q. The reactive power reference value Q is... ref The specific formula for calculating reactive power Q is as follows:

[0074]

[0075]

[0076] Among them, K p K i These represent the gain of the PI controller; U α i α and U β i β These represent the grid voltage and current on the α-axis and β-axis, respectively.

[0077] The DC reference voltage u dcref The input to the damper is obtained by using the AC grid frequency ω and the rated angular frequency ω0 as inputs, specifically using the following calculation formula:

[0078]

[0079] in, This indicates a low-pass filter, and K represents the gain stage.

[0080] The grid-side converter 3 can adjust according to the DC reference voltage u dcref The change adjusts the actual DC voltage u dc This, in turn, generates corresponding changes in active power on the AC side, damping the changes in the AC grid frequency ω, thereby suppressing power oscillations.

[0081] In this embodiment, under both DC control and reactive power control, the AC current reference values ​​i in the d-axis and q-axis are obtained respectively. dref i qref The dq transform uses the phase angle θ PLL Three-phase current i abc As input, obtain the current i along the d-axis and q-axis. d i q , and the i obtained above dref i qref Together, they serve as inputs to PI controllers three and four in the current control loop. Through SPWM modulation, the actual feedback frequency deviation and PQ feedback of the system are obtained, which are then used to generate the drive signal S. abc Based on this, the grid-side converter 3 is prompted to use the control strategy in the converter to suppress power oscillations in the AC power grid.

[0082] The control strategy of the grid-side converter 3 reacts on a millisecond time scale.

[0083] To verify the effectiveness of the proposed control strategy in suppressing offshore wind power oscillations, a PSCAD model of the offshore wind farm grid-connected system was constructed for simulation experiments. To induce power oscillations of varying degrees, this embodiment installs a fault-inducing device at the busbar of the power transmission line. This device can simulate various line faults to induce system oscillations.

[0084] Please see Figure 5 Taking a transmission line generating 200MW of power as an example, under stable power transmission conditions, a single-phase ground fault with a duration of 0.1 seconds is set at the busbar. Figure 5 As shown in Figure a, in the initial stage of the fault, the power transmitted by the system drops rapidly, and its power curve shows corresponding oscillations. Observation shows that during the fault oscillation period (within 0.1 seconds), when the fault has not yet been resolved, the system's transmission power is in an oscillating state, and its power is gradually recovering to the normal state of 200MW. The fault is resolved at 0.1 seconds, but the oscillation effect caused by the fault on the system continues. After adjusting the control strategy, after two oscillation cycles, the time is only about 0.5 seconds, and the system oscillation has been completely suppressed.

[0085] like Figure 5As shown in b: In the event of a single-phase ground fault lasting 0.2 seconds, even if the fault time is doubled, the system can still quickly suppress power oscillations and prevent the oscillations from lasting for a long time.

[0086] To further verify that the control strategy proposed in this application can still cope with and suppress the continued power oscillations even under more severe system failures, such as... Figure 5 As shown in Figure c: A two-phase ground fault (AB) with a duration of 0.2 seconds is set. Analysis of the fault curves shows that in the single-phase fault experiment, even if the fault is not cleared, the system's transmitted power can gradually recover to the steady-state value of 200MW in an oscillating manner. However, under a two-phase ground fault, the system cannot increase its transmitted power during the fault period, and can only maintain a power transmission of around 100MW, resulting in corresponding power oscillations. Through the above experimental analysis of power oscillation suppression, the control strategy proposed in this application has a fast, reliable, and stable performance in suppressing power oscillations in offshore wind power grid-connected systems.

[0087] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A PQ tracking feedback control strategy method based on offshore wind power frequency deviation dampers, characterized in that: The system includes building a flexible high-voltage AC transmission system for offshore wind power on PSCAD power system simulation software. The system includes a turbine-side converter, a grid-side converter, a step-up transformer, and transmission lines connected to the offshore wind turbine. The turbine-side converter is connected to the step-up transformer through the grid-side converter, and the step-up transformer is connected to a large-capacity power source through the transmission lines. Control strategies are set on the machine-side converter and the grid-side converter; The control strategy for the machine-side converter includes setting voltage control on the DC side of the machine-side converter and setting reactive power control on the AC side of the machine-side converter. The DC side of the machine-side converter is equipped with voltage control to achieve dynamic power balance of the system; The AC side of the converter is equipped with reactive power control to meet the reactive power requirements of offshore wind farms and can output the maximum wind power. The control strategy for the grid-side converter adopts reactive power and AC voltage control, specifically including the control of the frequency, reactive power, DC voltage, and current of the grid-side converter. This control method includes the following steps: Step 1. Obtain the three-phase voltage at the bus node through the grid-side converter. Three-phase current and DC voltage Three-phase voltage As input, the AC grid frequency at the bus node is obtained from the PLL phase-locked loop. Then, using three-phase voltage Three-phase current As input, the real-time reactive power Q is obtained through the instantaneous power calculator; Step 2. Using the AC power grid frequency obtained in Step 1 With the rated angular frequency Obtain reactive power reference value and the AC power grid frequency With the rated angular frequency As input to the damper, the DC reference voltage of the system is obtained. ; Step 3. Utilize the DC voltage from Step 1 The DC reference voltage obtained in step 2 As the input to PI controller one, it obtains the AC current reference value along the d-axis. The real-time reactive power Q obtained in step 1 is compared with the reactive power reference value obtained in step 2. This serves as the input to the second PI controller, thereby obtaining the AC current reference value along the q-axis. ; Step 4. Obtain the phase angle from the PLL in Step 1. With three-phase current As input to the dq transform, the outputs are the currents along the d and q axes, respectively. and ; Step 5. Use the d-axis AC current reference values ​​obtained in Steps 3 and 4 above. d-axis current q-axis AC current reference value q-axis current These are used as inputs to PI controller three and PI controller four, respectively, and their outputs are combined and input to the SPWM to obtain a drive signal after modulation. ; The converter on the machine side is equipped with voltage control on the DC side and reactive power control on the AC side. The control method specifically includes: (1) A DC voltage is applied to the DC side of the converter on the machine side. and DC voltage reference value As input, the AC current reference value in the d-axis is obtained through PI controller 5. ; (2) The AC side of the machine-side converter is connected to AC voltage. AC voltage reference value As input, the AC current reference value in the q-axis is obtained through the PI controller. ; (3) Set the reference values ​​of AC current on the d and q axes , Respectively with d-axis current and q-axis current As the input to PI controller 7 and PI controller 8, and the outputs of PI controller 7 and PI controller 8 are jointly input into SPWM, a drive signal is obtained after modulation; The input terminal of the machine-side converter is equipped with AC filter one, and the output terminal of the grid-side converter is equipped with AC filter two. The AC filter one and AC filter two are used to maintain the system bus voltage, eliminate harmonics, and compensate for reactive power.

2. The PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper according to claim 1, characterized in that: In step 1, the PLL phase-locked loop converts the three-phase voltage As input, obtain the AC power grid frequency. and phase angle ; Specifically, the three-phase voltage at the busbar in the abc coordinate system is... Transformed into d-axis voltage in dq coordinate system and q-axis voltage Then, using the q-axis voltage With q-axis reference voltage v qref As the transfer function of the phase-locked loop PI regulator Input to obtain AC power grid frequency and phase angle .

3. The PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper according to claim 2, characterized in that: The transfer function The specific formula used is as follows: （3） in, and These represent the proportional and integral coefficients of the PI control in the phase-locked loop (PLL), respectively.

4. The PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper according to claim 1, characterized in that: The grid-side converter can adjust based on reactive power reference values. The change in Q adjusts the actual reactive power; Among them, reactive power reference value The actual reactive power Q is specifically expressed using the following formula: （4） （5） in, , These represent the gains of the PI controller; , and , They represent in axis, The grid voltage and current under the shaft.

5. The PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper according to claim 1, characterized in that: The DC reference voltage Through AC power grid frequency With the rated angular frequency The input for the damper is obtained using the following formula: （6） in, This indicates a low-pass filter, and K represents the gain stage.

6. The PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper according to claim 1, characterized in that: The grid-side converter can adjust according to the DC reference voltage. The change adjusts the actual DC voltage. This, in turn, generates corresponding changes in active power on the AC side, damping the AC grid frequency. The changes.

7. The PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper according to claim 1, characterized in that: The control strategy of the grid-side converter reacts on a millisecond timescale.

8. The PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper according to claim 1, characterized in that: The transmission line includes submarine cables and overhead lines. The submarine cables are laid on the seabed and are used for long-distance offshore high-voltage AC power transmission. The elevated line is erected on land and is used to connect to the ground high-voltage transmission line grid.

9. The PQ tracking feedback control strategy method based on offshore wind power frequency deviation damper according to claim 8, characterized in that: The grounding layer of the elevated line is equipped with two ground wires.

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