A wind power frequency regulation control method based on virtual synchronization technology

Abstract

This invention discloses a wind power frequency regulation control method based on virtual synchronization technology, belonging to the field of virtual synchronization technology. The virtual synchronization control method is embedded into the normal control of wind turbine generators. After the wind turbine generator starts, when the virtual synchronization function is not enabled, the turbine operates according to the original traditional control mode. When the virtual synchronization function is enabled, the virtual synchronization control calculates the pitch angle and torque control commands that need to be adjusted based on grid fluctuations. These commands are then superimposed and judged with the normal pitch and torque control of the wind turbine to form the final control command, which is then sent to the pitch system and converter for execution. In other words, this invention addresses the shortcomings of existing wind power virtual synchronization frequency regulation control methods by controlling the wind turbine generator through two control modes: one with energy storage and one without, based on the virtual synchronization frequency regulation function of wind power and the operating characteristics of the wind turbine generator.

Description

Technical Field

[0001] This invention belongs to the field of wind power generation technology based on virtual synchronization technology, and particularly relates to a wind power frequency regulation control method based on virtual synchronization technology. Background Technology

[0002] With the energy crisis and environmental problems becoming increasingly severe, new energy sources, represented by wind power, are receiving more and more attention. In 2017, my country added 15.03 million kilowatts of grid-connected wind power capacity, bringing the cumulative grid-connected capacity to 164 million kilowatts, accounting for 9.2% of the total power generation capacity. The State Grid has become the world's largest and fastest-growing power grid in terms of the scale of new energy access.

[0003] The increasing proportion of new energy power generation, represented by wind power, in the power system has led to a lack of inertia and damping in the system. Virtual synchronous machine technology, by simulating the external characteristics of conventional synchronous generator units operating in grid connection, can provide effective power support to the grid when disturbances occur in grid frequency and voltage, and can effectively solve the impact of new energy power generation on the stability of the power system.

[0004] Traditional wind power control strategies aim for maximum power point tracking (MPPT). Depending on the generator's operating speed, wind turbine control is divided into minimum speed control, optimal power point tracking, constant speed, and constant power stages. Analysis of traditional wind power power characteristics and transmission chain characteristics, combined with the flexibility of wind power control, makes virtual synchronous frequency regulation of wind power possible. The wind turbine stores enormous rotational kinetic energy, and the relationship between the pitch angle and wind energy capture coefficient of variable-speed wind turbine generators provides multiple control methods for wind power participation in frequency regulation.

[0005] Research on virtual synchronous frequency regulation control technology for wind power mainly focuses on wind turbines with inertia and primary frequency regulation. The realization of inertia and primary frequency regulation functions primarily studies the regulation and support capabilities of wind turbine active power. Currently, large-megawatt wind turbines generally employ variable pitch control systems, which can adjust wind energy capture by regulating the blade pitch angle. However, existing virtual synchronous frequency regulation control methods for wind power are not accurate enough; therefore, a wind power frequency regulation control method based on virtual synchronization technology is needed. Summary of the Invention

[0006] The purpose of this invention is to provide a wind power frequency regulation control method based on virtual synchronization technology, thereby solving the shortcomings of existing wind power virtual synchronization frequency regulation control that is not accurate enough.

[0007] To achieve the above objectives, the present invention provides a wind power frequency regulation control method based on virtual synchronization technology, comprising the following steps:

[0008] Embed the virtual synchronous control method into the normal control of wind turbine units;

[0009] When the wind turbine is started, the controller determines whether the virtual synchronization control function is enabled. When the virtual synchronization control function is not enabled, the wind turbine operates according to the original traditional control mode. When the virtual synchronization function is enabled, the wind turbine is controlled through the virtual synchronization control strategy.

[0010] The virtual synchronous control strategy includes: calculating the pitch angle and torque control commands that need to be adjusted based on the fluctuations in the power grid, and after combining the normal pitch and torque control judgments of the wind turbine, forming the final control command and sending it to the pitch system and converter of the wind turbine for execution.

[0011] Preferably, the virtual synchronization control strategy includes active frequency regulation divided into an energy storage control mode and a non-energy storage control mode. The two modes are set according to the wind farm requirements, and both control modes have inertial function and primary frequency regulation function.

[0012] Preferably, the energy storage control mode is a control strategy when the wind turbine is in an energy storage off state, including the following steps:

[0013] When the wind turbine is in an energy storage off state, determine whether the inertial function of the wind turbine is enabled.

[0014] If the inertial function of the wind turbine is enabled, set the first inertial control strategy, and then determine whether the primary frequency regulation function of the wind turbine is enabled.

[0015] If the inertial function of the wind turbine is not enabled, then directly determine whether the primary frequency regulation function of the wind turbine is enabled.

[0016] When the primary frequency regulation function of the wind turbine is enabled, the first primary frequency regulation control strategy is set.

[0017] A first superposition strategy is set according to the first inertial control strategy and the first frequency regulation control strategy. The wind turbine responds to the first superposition strategy to complete the control.

[0018] When the primary frequency regulation function of the wind turbine is not enabled, the wind turbine responds to the first inertial control strategy and completes the control.

[0019] Preferably, the energy storage control mode is a control strategy when the wind turbine is in the energy storage on state, including the following steps:

[0020] When the wind turbine starts energy storage, set an energy storage control strategy to determine whether the energy storage of the wind turbine is complete.

[0021] When the energy storage of the wind turbine is completed, determine whether the inertial function of the wind turbine is enabled.

[0022] If the inertial function of the wind turbine is enabled, set the second inertial control strategy, and then determine whether the primary frequency regulation function of the wind turbine is enabled.

[0023] If the inertial function of the wind turbine is not enabled, then directly determine whether the primary frequency regulation function of the wind turbine is enabled.

[0024] When the primary frequency regulation function of the wind turbine is enabled, a second primary frequency regulation control strategy is set.

[0025] A second superposition strategy is set according to the second inertial control strategy and the second frequency regulation control strategy. The wind turbine responds to the second superposition strategy to complete the control.

[0026] When the primary frequency regulation function of the wind turbine is not enabled, the wind turbine responds to the second inertial control strategy to complete the control.

[0027] Preferably, the first inertial control strategy includes:

[0028] When the actual power output of the wind turbine is greater than 20%Pn and the grid frequency change exceeds 0.03Hz, the actual active power output at that moment is locked, and the required additional power output is calculated. The limit range of the required additional power output is within ±10% of the rated power of the unit.

[0029] The first inertial power of the wind turbine is determined based on the actual active power and the additional active power.

[0030] Preferably, the first frequency modulation control strategy includes:

[0031] When the actual power output of the wind turbine is greater than 20%Pn and the grid frequency change exceeds 0.03Hz, the actual active power output at that moment is locked, and the required additional power output is calculated. The limit range of the additional power output is -20% to 10% of the rated power of the unit.

[0032] The first frequency regulation power of the wind turbine is determined based on the actual active power and the additional power generated, and the first frequency regulation power is used to support the grid frequency until it is restored.

[0033] Preferably, obtaining the first superposition strategy based on the first inertial control strategy and the first frequency modulation control strategy includes:

[0034] The wind turbine prioritizes responding to the first inertial power output by the first inertial control strategy, and the response is a step response;

[0035] After responding to the first inertial power, the wind turbine continues to respond to the first frequency regulation power output by the first primary frequency regulation control strategy. The response of the first frequency regulation power is set with a fixed ramp rate.

[0036] The first superimposed power is determined based on the first inertial power output by the first inertial control strategy and the first frequency modulation power output by the first frequency modulation control strategy. The first superimposed power is divided by the real-time speed to obtain the torque command, which is then sent to the converter of the wind turbine for execution.

[0037] Preferably, the energy storage control strategy includes: using pitch regulation control to achieve energy storage of the wind turbine, with the stored power being 10% of the rated power of the turbine.

[0038] Preferably, the second inertial control strategy has the same method steps as the first inertial strategy, but the specific parameters are adjusted according to the energy storage situation; the second frequency modulation control strategy has the same method steps as the first frequency modulation control strategy, but the specific parameters are adjusted according to the energy storage situation; and the second superposition strategy has the same method steps as the first superposition strategy.

[0039] Compared with existing technologies, the present invention has the following advantages:

[0040] The wind power frequency regulation control method based on virtual synchronization technology provided by this invention embeds the virtual synchronization control method into the normal control of the wind turbine. After the wind turbine starts up, when the virtual synchronization function is not enabled, the wind turbine operates according to the original traditional control mode. When the virtual synchronization function is enabled, the virtual synchronization control calculates the pitch angle and torque control commands that need to be adjusted based on grid fluctuations. These commands are then superimposed and judged with the normal pitch and torque control of the wind turbine to form the final control command, which is then sent to the pitch system and converter for execution. This invention enables wind power frequency regulation control, increasing power output. Specifically, this invention simulates the external characteristics of a traditional synchronous generator set to develop a virtual synchronous machine for wind turbines, giving the wind turbine frequency regulation characteristics similar to those of a traditional synchronous generator set. Regarding the wind power virtual synchronous frequency regulation function, combined with the operating characteristics of the wind turbine, it controls the wind turbine through two control modes: one with energy storage and one without, based on active power frequency regulation, thus overcoming the shortcomings of existing wind power virtual synchronous frequency regulation control methods that are not accurate enough. Attached Figure Description

[0041] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the structure of the wind power virtual synchronous machine connected to the wind turbine generator according to the present invention;

[0043] Figure 2 This is a flowchart of the wind power frequency regulation control method based on virtual synchronization technology of the present invention;

[0044] Figure 3 This is a flowchart of the virtual synchronization control strategy of the present invention. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. 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.

[0046] like Figure 2 As shown, the wind power frequency regulation control method based on virtual synchronization technology provided by the present invention includes the following steps:

[0047] S1. Embed the virtual synchronous control method into the normal control of the wind turbine;

[0048] Specifically, such as Figure 1 The diagram shows the structure of the virtual synchronous machine connected to the wind turbine generator set. The output terminal of the generator set is connected to the power grid. The virtual synchronous control system is connected to the generator set's generator-side converter, grid-side converter, and pitch system, respectively. The main control system is connected to the virtual synchronous control system and the pitch system, respectively.

[0049] S2. When the wind turbine is started, the controller determines whether the virtual synchronization control function is enabled. When the virtual synchronization control function is not enabled, the wind turbine operates according to the original traditional control mode. When the virtual synchronization function is enabled, the wind turbine is controlled through the virtual synchronization control strategy.

[0050] The virtual synchronous control strategy includes: calculating the pitch angle and torque control commands that need to be adjusted based on the fluctuations in the power grid, and after combining the normal pitch and torque control judgments of the wind turbine, forming the final control command and sending it to the pitch system and converter of the wind turbine for execution.

[0051] S3. Considering the fluctuation of wind speed during actual operation, in order to stabilize the power output during the power support process, the operating conditions of the unit may exceed the limit. It is necessary to set the "power-speed" protection limit. Different models need to plan the protection curve according to the simulation and calculation results. When the protection limit is exceeded, the strategy will immediately exit the active frequency regulation function and switch to normal torque control.

[0052] The aforementioned wind power frequency regulation control method based on virtual synchronization technology embeds the virtual synchronization control method into the normal control of the wind turbine. After the wind turbine starts up, when the virtual synchronization function is not enabled, the turbine operates according to the original traditional control mode. When the virtual synchronization function is enabled, the virtual synchronization control calculates the pitch angle and torque control commands that need to be adjusted based on grid fluctuations. These commands are then superimposed and judged with the normal pitch and torque control of the wind turbine to form the final control command, which is then sent to the pitch system and converter for execution. This invention enables wind power frequency regulation control, increases power output, and ensures accurate energy reserve for the wind turbine under all wind conditions.

[0053] Specifically, Figure 3 The flowchart of the virtual synchronization control strategy of the present invention is shown. The virtual synchronization control strategy includes active frequency regulation divided into energy storage control mode and non-energy storage control mode. The two modes are set according to the wind farm requirements. Both control modes have inertial function and primary frequency regulation function. Enable switches are set for each mode to facilitate starting or stopping as needed.

[0054] In the non-energy storage control mode, under stable grid conditions, the wind turbines follow the conventional control strategy; when the grid frequency fluctuates, the wind turbines rely on the inertia of the wind turbines to reduce the wind turbine speed by forcibly increasing the generator excitation current, thus converting the rotational kinetic energy of the wind turbines into electrical energy output.

[0055] In energy storage control mode, based on the power generation corresponding to the current wind speed of the wind turbine, the pitch angle is reserved through pitch control to reduce wind energy capture, thereby achieving the purpose of reserving reserve capacity. When the grid frequency fluctuates downward, the reserved pitch angle is released to increase wind energy capture, thereby increasing the power generation. When the grid frequency fluctuates upward, the rotor speed is increased through rotor overspeed control. When the rotor speed reaches the rated speed, the pitch angle is increased in conjunction with pitch control to reduce wind energy capture, thereby reducing the unit's output power.

[0056] The energy storage control mode is a control strategy for wind turbines when energy storage is not activated, and includes the following steps:

[0057] S11. When the wind turbine is in the energy storage off state, determine whether the inertial function of the wind turbine is enabled. If the inertial function of the wind turbine is enabled, set the first inertial control strategy and proceed to the next step S12. If the inertial function of the wind turbine is not enabled, proceed directly to step S12.

[0058] S12. Determine whether the primary frequency regulation function of the wind turbine is enabled. When the primary frequency regulation function of the wind turbine is enabled, set the first primary frequency regulation control strategy, set the first superposition strategy according to the first inertial control strategy and the first frequency regulation control strategy, and the wind turbine responds to the first superposition strategy to complete the control. When the primary frequency regulation function of the wind turbine is not enabled, the wind turbine responds to the first inertial control strategy to complete the control.

[0059] The energy storage control mode is a control strategy when the wind turbine is in the energy storage activation state, including the following steps:

[0060] S21. When the wind turbine starts energy storage, set the energy storage control strategy, determine whether the wind turbine has completed energy storage, and proceed to the next step S22 when the wind turbine has completed energy storage; otherwise, end the control and re-determine whether the wind turbine has started energy storage.

[0061] S22. Determine whether the inertial function of the wind turbine is enabled. If the inertial function of the wind turbine is enabled, set the second inertial control strategy and then proceed to the next step S23. If the inertial function of the wind turbine is not enabled, proceed directly to the next step S23.

[0062] S23. Determine whether the primary frequency regulation function of the wind turbine is enabled. When the primary frequency regulation function of the wind turbine is enabled, set a second primary frequency regulation control strategy. Set a second superposition strategy according to the second inertial control strategy and the second frequency regulation control strategy. The wind turbine responds to the second superposition strategy to complete the control. When the primary frequency regulation function of the wind turbine is not enabled, the wind turbine responds to the second inertial control strategy to complete the control.

[0063] Specifically, in step S11, the first inertial control strategy is the control strategy for the wind turbine to respond to the grid frequency change rate when energy storage is not activated. The first inertial control strategy includes:

[0064] When the actual power generated by the wind turbine is greater than 20% of Pn and the grid frequency change exceeds 0.03Hz, the actual active power P0 generated at that moment is locked, and the first required additional power generation is calculated. The corresponding calculation formula is as follows: Among them, T J Set to an adjustable parameter (default setting is 5), P N f is the rated power of the unit. N Here, f is the system's rated frequency, f is the real-time frequency at the grid connection point, t is the inertial time constant, and the limit range of ΔP1 is -10%P. N ~+10%P N ;

[0065] The first inertial power P of the wind turbine is determined based on the actual generated active power and the first additional generated power. 11=P0+ΔP1.

[0066] Specifically, in step S12, the first frequency regulation control strategy is the control strategy for wind turbine units to respond to changes in grid frequency when energy storage is not activated. The first frequency regulation control strategy includes:

[0067] When the actual power generated by the wind turbine is greater than 20% of Pn and the grid frequency change exceeds 0.03Hz, the actual active power P0 generated at that moment is locked, and the second required additional power generation is calculated. K f The active frequency modulation coefficient is ΔP2, where Δf is the frequency change, and the limit range of ΔP2 is -20%P. N ~10% P N Inside;

[0068] The first frequency regulation power P of the wind turbine is determined based on the actual generated active power and the increased generated power. 12 =P0 + ΔP2;

[0069] The active power upward support time is set to an adjustable parameter (default setting is 10s). When the active power is downward supported, it can support for a long time until the grid frequency is restored, that is, the first frequency regulation power support is until the grid frequency is restored.

[0070] Specifically, in step S12, the first superposition strategy is obtained based on the first inertial control strategy and the first frequency modulation control strategy, including:

[0071] The wind turbine prioritizes responding to the first inertial power output by the first inertial control strategy, and the response is a step response;

[0072] After responding to the first inertial power, the wind turbine continues to respond to the first frequency regulation power output by the first primary frequency regulation control strategy. The response of the first frequency regulation power is set with a fixed ramp rate.

[0073] The first superimposed power is determined based on the first inertial power output by the first inertial control strategy or the first frequency modulation power output by the first frequency modulation control strategy (i.e., the first superimposed power can be either the first inertial power or the first frequency modulation power). The first superimposed power P1 is divided by the real-time speed to obtain the torque command T1, which is sent to the converter of the wind turbine for execution. After the action is completed, it switches back to the normal torque control output. A modulation process is added during the torque switching process to achieve smooth switching.

[0074] Specifically, in step S21, the energy storage control strategy includes: using pitch regulation control to achieve energy storage of the wind turbine, with the stored power being 10% of the rated power of the turbine.

[0075] The principle of variable pitch energy storage is based on the relationship between pitch angle and power. Under certain wind speed conditions, the larger the pitch angle, the greater the energy that can be stored.

[0076] Based on simulation results, the energy storage curve is calculated and incorporated into the energy storage control strategy. After virtual synchronous control is activated and energy storage is enabled, the pitch angle output by the energy storage control strategy is superimposed and judged with the normal pitch control to ensure that the wind turbine pitch angle reserve can meet 10% P. N The power is reserved.

[0077] The second inertial control strategy has the same method steps as the first inertial strategy, but the specific parameters are adjusted according to the energy storage situation; the second frequency modulation control strategy has the same method steps as the first frequency modulation control strategy, but the specific parameters are adjusted according to the energy storage situation; the second superposition strategy has the same method steps as the first superposition strategy, and will not be repeated here.

[0078] In summary, the present invention provides a wind power frequency regulation control method based on virtual synchronization technology, which sets the reserved pitch angle limit based on the current active power, thereby achieving accurate energy reservation of the wind turbine under all wind conditions.

[0079] The above description only discloses specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A wind power frequency regulation control method based on virtual synchronization technology, characterized in that, Includes the following steps: Embed the virtual synchronous control method into the normal control of wind turbine units; When the wind turbine is started, the controller determines whether the virtual synchronization control function is enabled. When the virtual synchronization control function is not enabled, the wind turbine operates according to the original traditional control mode. When the virtual synchronization function is enabled, the wind turbine is controlled through the virtual synchronization control strategy; The virtual synchronous control strategy includes: calculating the pitch angle and torque control commands that need to be adjusted based on the fluctuation of the power grid, and after combining the normal pitch and torque control judgment of the wind turbine, forming the final control command and sending it to the pitch system and converter of the wind turbine for execution; The virtual synchronous control strategy includes active frequency regulation divided into energy storage control mode and non-energy storage control mode. The two modes are set according to the wind farm requirements, and both control modes have inertial function and primary frequency regulation function. The energy storage control mode is the control strategy when the wind turbine is in an energy storage off state, including the following steps: When the wind turbine is in an energy storage off state, determine whether the inertial function of the wind turbine is enabled. If the inertial function of the wind turbine is enabled, set the first inertial control strategy, and then determine whether the primary frequency regulation function of the wind turbine is enabled. If the inertial function of the wind turbine is not enabled, then directly determine whether the primary frequency regulation function of the wind turbine is enabled. When the primary frequency regulation function of the wind turbine is enabled, the first primary frequency regulation control strategy is set. A first superposition strategy is set according to the first inertial control strategy and the first primary frequency regulation control strategy. The wind turbine responds to the first superposition strategy to complete the control. When the primary frequency regulation function of the wind turbine is not enabled, the wind turbine responds to the first inertial control strategy and completes the control.

2. The wind power frequency regulation control method based on virtual synchronization technology according to claim 1, characterized in that, The energy storage control mode is the control strategy when the wind turbine is in the energy storage enabled state, including the following steps: When the wind turbine starts energy storage, set an energy storage control strategy to determine whether the energy storage of the wind turbine is complete. When the energy storage of the wind turbine is completed, determine whether the inertial function of the wind turbine is enabled. If the inertial function of the wind turbine is enabled, set the second inertial control strategy, and then determine whether the primary frequency regulation function of the wind turbine is enabled. If the inertial function of the wind turbine is not enabled, then directly determine whether the primary frequency regulation function of the wind turbine is enabled. When the primary frequency regulation function of the wind turbine is enabled, a second primary frequency regulation control strategy is set. A second superposition strategy is set according to the second inertial control strategy and the second primary frequency regulation control strategy. The wind turbine responds to the second superposition strategy to complete the control. When the primary frequency regulation function of the wind turbine is not enabled, the wind turbine responds to the second inertial control strategy to complete the control.

3. The wind power frequency regulation control method based on virtual synchronization technology according to claim 1, characterized in that, The first inertial control strategy includes: When the actual power output of the wind turbine is greater than 20%Pn and the grid frequency changes by more than 0.03Hz, the actual active power output at that moment is locked, and the required additional power output is calculated. The limit range of the required additional power output is within ±10% of the rated power of the unit. The first inertial power of the wind turbine is determined based on the actual active power and the additional active power.

4. The wind power frequency regulation control method based on virtual synchronization technology according to claim 1, characterized in that, The first frequency modulation control strategy includes: When the actual power output of the wind turbine is greater than 20%Pn and the grid frequency change exceeds 0.03Hz, the actual active power output at that moment is locked, and the required additional power output is calculated. The limit range of the additional power output is within -20% to 10% of the rated power of the unit. The first frequency regulation power of the wind turbine is determined based on the actual active power and the additional power generated, and the first frequency regulation power is used to support the grid frequency until it is restored.

5. The wind power frequency regulation control method based on virtual synchronization technology according to claim 1, characterized in that, The first superposition strategy is obtained based on the first inertial control strategy and the first primary frequency modulation control strategy, including: The wind turbine prioritizes responding to the first inertial power output by the first inertial control strategy, and the response is a step response; After responding to the first inertial power, the wind turbine continues to respond to the first frequency regulation power output by the first primary frequency regulation control strategy. The response of the first frequency regulation power is set with a fixed ramp rate. The first superimposed power is determined based on the first inertial power output by the first inertial control strategy and the first frequency modulation power output by the first frequency modulation control strategy. The first superimposed power is divided by the real-time speed to obtain the torque command, which is then sent to the converter of the wind turbine for execution.

6. The wind power frequency regulation control method based on virtual synchronization technology according to claim 1, characterized in that, The energy storage control strategy includes: using pitch regulation control to achieve energy storage of the wind turbine, with the stored power being 10% of the rated power of the turbine.

7. The wind power frequency regulation control method based on virtual synchronization technology according to claim 2, characterized in that, The second inertial control strategy has the same method steps as the first inertial strategy, but the specific parameters are adjusted according to the energy storage situation; the second primary frequency regulation control strategy has the same method steps as the first primary frequency regulation control strategy, but the specific parameters are adjusted according to the energy storage situation; the second superposition strategy has the same method steps as the first superposition strategy.

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