A frequency control method and device for combining wind turbine and energy storage

Abstract

The present invention discloses a frequency control method and device combining a wind turbine and energy storage, comprising: obtaining power system frequency measurement data, wind turbine unit data, and energy storage data; giving priority to using energy storage to provide frequency response when the system frequency drops, and enabling the wind turbine frequency response if the energy storage power reaches an upper limit and the system frequency deviation or frequency change rate is still greater than a certain threshold. The power margin is calculated based on the wind turbine rotor speed and the maximum wind energy tracking coefficient, and the energy margin is calculated based on the rated speed and the moment of inertia, and the wind turbine frequency response adaptive control coefficient is further calculated. By considering the synergy between the wind turbine and the energy storage, the impact on the maximum wind energy capture of the wind turbine is reduced; through the wind turbine adaptive control coefficient, the frequency response capability of wind turbines with different speeds can be most effectively utilized when the system frequency is greatly disturbed.

Description

Technical Field

[0001] The present invention relates to the technical field of power system frequency control, and in particular to a frequency control method and device combining a wind turbine and energy storage. Background Art

[0002] With the large-scale integration of renewable energy into the power grid, a large number of converters composed of power electronic devices have been connected to the power grid, making the proportion of traditional units in the power grid lower and lower, resulting in reduced system equivalent inertia and damping, and gradually worsening the problem of system frequency stability.

[0003] Among them, offshore wind farms often have large rated capacity and relatively stable wind speeds, and there is considerable rotational kinetic energy to be developed in offshore wind turbines. However, at present, there are certain limitations for wind turbines and energy storage systems to participate in frequency response alone. For example, the frequency response of wind turbines is controlled by a single MPPT (Maximum power point tracking) control method. Among them, the frequency response control parameters of wind turbines are often set uniformly. The unified control parameters do not take into account the operating characteristics and frequency response capabilities of different wind turbines, and cannot maximize the use of wind turbine kinetic energy. Summary of the invention

[0004] The technical problem to be solved by the present invention is: a frequency control method and device combining a wind turbine and energy storage, so as to maximize the utilization of wind turbine kinetic energy.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A frequency control method for a wind turbine combined with energy storage, comprising:

[0007] Obtaining system frequency, wind turbine unit data and energy storage data; the wind turbine unit data includes the current rotor speed, rated speed, moment of inertia, and maximum wind energy tracking coefficient;

[0008] The wind turbine power margin is calculated according to the current rotation speed of the rotor and the maximum wind energy tracking coefficient, and the wind turbine energy margin is calculated according to the current rotation speed, rated rotation speed and moment of inertia of the rotor;

[0009] Calculating a frequency response adaptive control coefficient of the fan according to the power margin and the energy margin;

[0010] When the system frequency drops, the energy storage and the way in which the fan provides frequency response are determined according to the frequency drop situation, and the frequency response power of the fan is obtained according to the frequency response adaptive control coefficient.

[0011] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0012] A frequency control device for a combined wind turbine and energy storage device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, each step in the above-mentioned frequency control method for a combined wind turbine and energy storage device is implemented.

[0013] The beneficial effect of the present invention is that by combining the wind turbine unit data and the energy storage data, the power margin and the energy margin of the wind turbine can be adjusted to the frequency regulation capability of the wind turbine at the current moment, that is, the power margin and the energy margin can be adjusted according to the current wind turbine parameters, and based on this, the virtual inertia control coefficient of the wind turbine is adjusted. Compared with the existing method of uniformly adjusting the control parameters, the virtual inertia control coefficient is adjusted based on the real-time parameters of the wind turbine, which takes into account the operating characteristics and frequency response capabilities of different wind turbines, and can maximize the use of the kinetic energy of the wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A frequency response control coefficient setting process of a frequency control method for combining a wind turbine and energy storage in an embodiment of the present invention;

[0015] Figure 2 It is a flowchart of a frequency control method for combining a wind turbine and energy storage in an embodiment of the present invention;

[0016] Figure 3 A block diagram of a frequency response control of a wind turbine in a frequency control method combining a wind turbine and energy storage in an embodiment of the present invention;

[0017] Figure 4 It is a structural schematic diagram of an application system of a frequency control method for combining a wind turbine and energy storage in an embodiment of the present invention;

[0018] Figure 5 A flow chart of application system steps of a frequency control method for a wind turbine combined with energy storage in an embodiment of the present invention;

[0019] Figure 6 A topological diagram of an offshore wind-storage combined transmission system in a frequency control method for combining wind turbines and energy storage in an embodiment of the present invention;

[0020] Figure 7 A power margin and energy margin variation diagram considering the fan speed in a frequency control method for combining a fan and energy storage in an embodiment of the present invention;

[0021] Figure 8 An output power diagram of auxiliary frequency modulation output of a wind turbine in different wind speed regions in a frequency control method for combining a wind turbine with energy storage in an embodiment of the present invention;

[0022] Fig. 9A system frequency response diagram under different frequency modulation strategies in a frequency control method for combining a wind turbine and energy storage in an embodiment of the present invention;

[0023] Fig.10 Schematic diagram of the structure of a frequency control device combining a wind turbine and energy storage in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0025] A frequency control method for a wind turbine combined with energy storage, comprising:

[0026] Obtaining system frequency, wind turbine unit data and energy storage data; the wind turbine unit data includes the current rotor speed, rated speed, moment of inertia, and maximum wind energy tracking coefficient;

[0027] The wind turbine power margin is calculated according to the current rotation speed of the rotor and the maximum wind energy tracking coefficient, and the wind turbine energy margin is calculated according to the current rotation speed, rated rotation speed and moment of inertia of the rotor;

[0028] Calculating a frequency response adaptive control coefficient of the fan according to the power margin and the energy margin;

[0029] When the system frequency drops, the energy storage and the way in which the fan provides frequency response are determined according to the frequency drop situation, and the frequency response power of the fan is obtained according to the frequency response adaptive control coefficient.

[0030] From the above description, it can be seen that the beneficial effects of the present invention are: by combining the wind turbine unit data and the energy storage data, the power margin and the energy margin of the wind turbine can be adjusted to the frequency regulation capability of the wind turbine at the current moment, that is, the power margin and the energy margin can be adjusted according to the current wind turbine parameters, and based on this, the virtual inertia control coefficient of the wind turbine is adjusted. Compared with the existing method of uniformly setting the control parameters, the virtual inertia control coefficient is adjusted based on the real-time parameters of the wind turbine, which takes into account the operating characteristics and frequency response capabilities of different wind turbines and can maximize the utilization of the kinetic energy of the wind turbine.

[0031] Furthermore, the energy storage and wind turbine provide frequency response in the following specific ways:

[0032] The system frequency is monitored in real time. If the system frequency is lower than the frequency modulation dead zone, the energy storage is used to provide frequency response first.

[0033] If the energy storage discharge power reaches the upper limit, and the system frequency deviation or frequency drop rate is greater than a preset threshold, an action signal is sent to the fan to start the fan frequency response;

[0034] After the fan receives the action signal, it calculates the power margin and energy margin of the fan based on the current state of the fan, and calculates the adaptive control coefficient to control the frequency response power of the fan;

[0035] The frequency response process ends according to the system frequency recovery situation.

[0036] From the above description, it can be seen that the method proposed in the present invention is mainly aimed at the situation where the frequency drops after the power system is disturbed. The wind turbine unit cooperates with energy storage to provide virtual inertia and frequency modulation power support to accelerate the recovery of system frequency.

[0037] Furthermore, the power margin of the wind turbine is calculated as follows:

[0038] The power margin is calculated based on the current rotor speed and the maximum wind energy tracking coefficient:

[0039]

[0040] In the formula, k MPPTi is the maximum wind energy tracking coefficient of the i-th wind turbine, ω wi is the rotor speed of the i-th fan at the current moment, P wn is the maximum output power of the fan, a i is the power margin of the i-th wind turbine at the current moment.

[0041] From the above description, it can be seen that the current power margin of the wind turbine is obtained based on the current maximum wind energy tracking coefficient, rotor speed and maximum output power of the wind turbine, which can accurately describe the current operating condition of the wind turbine.

[0042] Further, the energy margin is calculated according to the current speed, rated speed and moment of inertia of the wind turbine rotor, including:

[0043]

[0044] In the formula, J w is the moment of inertia coefficient of the fan, ω wn Rated speed; wi is the rotor speed of the i-th fan at the current moment, b i is the energy margin of the i-th wind turbine.

[0045] From the above description, it can be seen that the current energy margin of the wind turbine is obtained through the rotor speed, moment of inertia coefficient and rated speed of the wind turbine, so that the speed of the wind turbine can be judged by the energy margin and a suitable power regulation strategy can be provided.

[0046] Furthermore, the fan unit data also includes the maximum output power, rated frequency and regulation coefficient of the fan;

[0047] The frequency response adaptive control coefficient of the wind turbine is calculated according to the power margin and the energy margin, specifically:

[0048] The differential coefficient of the virtual inertia control of the fan is calculated according to the rotational inertia coefficient and the rated speed, and the proportional coefficient of the primary frequency modulation control of the fan is calculated according to the maximum output power, rated frequency and the differential coefficient of the fan;

[0049] Correcting the differential coefficient by the power margin to obtain a corrected differential coefficient, and correcting the proportional coefficient by the energy margin to obtain a corrected proportional coefficient;

[0050] The differential coefficient is:

[0051]

[0052] In the formula, K di represents the differential coefficient of the i-th fan, J w is the moment of inertia coefficient of the fan, ω wn Rated speed;

[0053] The differential coefficient is corrected by the power margin to obtain a corrected differential coefficient:

[0054]

[0055] In the formula, represents the modified differential coefficient, a i is the power margin of the i-th wind turbine at the current moment;

[0056] The proportionality factor is:

[0057]

[0058] In the formula, K pi represents the proportionality coefficient of the i-th fan, P wn Indicates the maximum output power of the fan, f n represents the rated power, σ represents the adjustment coefficient;

[0059] The proportional coefficient is corrected by the energy margin to obtain the corrected proportional coefficient:

[0060]

[0061] In the formula, represents the correction proportionality coefficient, b i is the energy margin of the i-th wind turbine at the current moment.

[0062] From the above description, it can be seen that the proportional coefficient is calculated by the maximum output power, rated frequency, adjustment coefficient and frequency change of the fan, and the differential coefficient is calculated according to the moment of inertia coefficient and the rated speed. The proportional coefficient and the differential coefficient are corrected by the energy margin and the power margin respectively, so that the proportional coefficient and the differential coefficient can be adjusted according to the current operating conditions of the fan, so that the obtained virtual inertia control system can more effectively adjust the power of the fan to reach the corresponding operating frequency.

[0063] Furthermore, the output power variation of the fan frequency response is obtained according to the modified differential coefficient, the modified proportional coefficient and the frequency variation:

[0064]

[0065] Where ΔP w represents the virtual inertia control coefficient, represents the modified differential coefficient of the i-th fan, It represents the correction proportional coefficient of the i-th fan, and Δf represents the frequency change.

[0066] Furthermore, when the system frequency drops, the power of the fan and energy storage jointly providing frequency modulation and inertia response is obtained according to the frequency drop amplitude, the current state of the fan and energy storage, and the adaptive control coefficient of the fan, specifically:

[0067] When the system frequency drops and is lower than the frequency regulation dead zone, the frequency regulation response is provided in the following priority order: First, the energy storage outputs the frequency regulation power in response to the system frequency drop. At the same time, the wind farm receives the frequency change signal, and the controller calculates the current wind turbine frequency regulation capability, sets the adaptive control coefficient, and waits for the action signal. If the energy storage discharge power reaches the upper limit, and the system frequency deviation or the frequency drop rate is still greater than a certain threshold, an action signal is sent to the wind turbine to start the wind turbine frequency response. If it is not reached, the energy storage system continues to participate in the system frequency response alone. The system frequency deviation threshold is temporarily set to -0.2Hz, and the frequency drop rate threshold is -0.1Hz / s, which can be adjusted according to the actual situation of the power system.

[0068] Another embodiment of the present invention provides a frequency control device for a combined wind turbine and energy storage, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the various steps in the above-mentioned combined frequency control method for a wind turbine and energy storage when executing the computer program.

[0069] The frequency control method and device for combining a wind turbine and energy storage provided by the present invention can be applied to the application scenario of wind turbine frequency regulation, which is described below through specific implementation methods:

[0070] Embodiment 1

[0071] Please refer to Figure 1 as well as Figure 2 , a frequency control method for a wind turbine combined with energy storage, comprising:

[0072] S0. Real-time monitoring of the system frequency of the wind turbine unit. If the system frequency is lower than the frequency modulation dead zone, for example, the frequency modulation dead zone is set to: f=49.97Hz, then execute steps S1-S5, that is, the wind storage jointly participates in frequency control and inertia response, and is adjusted through an adaptive parameter calculator. Under certain conditions, the wind turbine releases kinetic energy by changing the rotor speed to provide additional power support; if the system frequency is higher than the frequency threshold, the power of the wind turbine unit is controlled based on the maximum power tracking control method.

[0073] According to the fan design, the upper and lower limits of the rotor speed are:

[0074] ω wmin <ω w <ω wmax ; (1)

[0075] Among them, ω wmin The rotor speed corresponding to the fan cut-in wind speed is generally 0.3 times the rated speed of the fan. wmax is the maximum speed of the wind turbine, which is generally 1.2 times the rated speed of the wind turbine. The wind turbine should return to the initial MPPT operating point after the frequency modulation is completed, and the speed recovery constraint is:

[0076] ω ∞ =ω MPPT ; (2)

[0077] In the formula, ω ∞ is the stable speed value of the fan after exiting frequency modulation, ω MPPT It is the speed value of the fan under MPPT control.

[0078] S1. Obtain system frequency (power system frequency measurement data), wind turbine unit data and energy storage data; wind turbine unit data includes rotor speed, maximum wind energy tracking coefficient, rated speed and moment of inertia, as well as wind turbine rated output power, current output power and regulation coefficient; energy storage data includes rated output power and current output power of energy storage.

[0079] S2. When the system frequency drops and is lower than the frequency modulation dead zone, the energy storage first provides frequency modulation and inertia response, that is, according to the frequency control and inertia response control signals, the output power P B If the energy storage discharge power does not reach the upper limit, the energy storage will provide frequency regulation and inertia response alone. If the energy storage discharge power reaches the upper limit, and the system frequency deviation or frequency drop rate is still greater than a certain threshold, an action signal will be sent to the fan to start the fan frequency response, such as Figure 2 As shown. Among them, the system frequency deviation or frequency drop rate threshold can be adjusted according to the actual situation of the power system. For example, the system frequency deviation is -0.2Hz (that is, the system frequency is still less than 49.8Hz), or the frequency drop rate is less than -0.1Hz / s, indicating that the frequency and inertia response provided by energy storage alone can no longer meet the frequency stability requirements of the power system, and it is necessary to further introduce the wind turbine power increment to control the system frequency. That is: execute S3-S4 to determine the control coefficient of the wind turbine, and then execute step S5 to determine the final output power of the wind turbine. During the frequency modulation process, the output power of the wind turbine includes the current output power P w0 and frequency response output power ΔP w , the sum of which cannot exceed the rated output power, that is, the fan output power constraint:

[0080] P wmin <P w0 +ΔP w <P wn ; (3)

[0081] Where P wmin is the minimum output power of the fan, P wn is the rated output power of the fan; taking the fan response frequency drop as an example, the maximum output power that the fan can increase is ΔP wmax :

[0082] ΔP wmax =P wn -P w0 (4)

[0083] S3. Calculate the power margin of the wind turbine according to the rotor speed and the maximum wind energy tracking coefficient, and calculate the energy margin of the wind turbine according to the rated speed and the moment of inertia;

[0084] According to the corresponding relationship between the wind turbine rotor speed and wind speed, different wind speed zones are divided into high, medium and low wind speed zones according to the speed limit constraint. The low and medium wind speed zones correspond to the wind turbine MPPT control zone, and the high wind speed zone corresponds to the wind turbine constant speed control zone. Definition a i is the power margin of the i-th wind turbine in the wind farm at the current moment. The power margin is calculated as follows:

[0085]

[0086] In the formula, k MPPTi is the maximum wind energy tracking coefficient of the i-th wind turbine, ω wi is the rotor speed of the i-th fan at the current moment, P wn is the maximum output power of the fan, a i is the power margin of the i-th wind turbine at the current moment.

[0087] At the same time, assuming that the mechanical power input of the fan remains unchanged in a short period of time, the energy source for the fan to provide frequency modulation response comes entirely from the change in rotor kinetic energy. Definition b i is the energy margin of the i-th wind turbine at the current moment. The energy margin is calculated as follows:

[0088]

[0089] In the formula, J w is the moment of inertia coefficient of the fan, ω wn Rated speed; wi is the rotor speed of the i-th fan at the current moment, b i is the energy margin of the i-th wind turbine.

[0090] Combining equations (4)-(6), it can be seen that if the wind speed is low at the current moment and the basic output power of the fan is small, the fan has a large space to increase the output power, but the rotor kinetic energy margin is small, and can only provide a short-term upward adjustment power. If the wind speed is high at the current moment, the rotor kinetic energy margin is large, but the fan has a small space to increase the output power, and can provide a relatively long but smaller upward adjustment power.

[0091] S4. The control coefficient of the frequency response provided by the fan is calculated based on the power margin and energy margin, and the power increment of the fan is obtained based on the control coefficient. Among them, the fan participates in the frequency response by combining primary frequency modulation control and virtual inertia control, and adds a response link to the frequency change rate and frequency deviation on the original power reference value. The energy source is the rotational kinetic energy stored in the fan rotor. However, in the existing method, the fan frequency response control parameters are generally set uniformly, without considering the influencing factors such as wind speed and fan operating status, and the uniform control parameters may cause the fan to shut down due to too low speed or cause secondary frequency reduction. In this example, the virtual inertia control coefficient is optimized based on the two indicators of power margin and energy margin, so that the fan in different operating states plays different roles in the frequency response strategy. The specific method is as follows:

[0092] S41. The differential coefficient is calculated according to the moment of inertia coefficient and the rated speed, and the differential coefficient is corrected by the power margin to obtain the corrected differential coefficient:

[0093]

[0094] In the formula, K di represents the differential coefficient of the i-th fan, J w is the moment of inertia coefficient of the fan, ω wn Rated speed; represents the modified differential coefficient, a i is the power margin of the i-th wind turbine at the current moment; K diIt mainly affects the frequency drop speed at the initial stage of the system frequency response and the time to reach the minimum frequency value. When the frequency drops, K increases. di value, a single fan releases the same rotor inertia in a shorter time, has a larger short-term output power, and has a stronger frequency support capability, so K di It determines the inertia response characteristics of the virtual inertia control of the wind turbine.

[0095] S42. Calculate the proportional coefficient according to the maximum output power, rated frequency and adjustment coefficient of the fan, and correct the proportional coefficient by the energy margin to obtain the corrected proportional coefficient:

[0096]

[0097] In the formula, K pi represents the proportionality coefficient of the i-th fan, P wn Indicates the maximum output power of the fan, f n represents the rated power, σ represents the adjustment coefficient; represents the correction proportionality coefficient, b i is the energy margin of the i-th wind turbine at the current moment; K pi It mainly affects the minimum frequency value in the system frequency response process and the rotor kinetic energy released by the system frequency regulation, and determines the primary frequency regulation characteristics of the virtual inertia control of the wind turbine.

[0098] S43. Obtain the change in the fan output power according to the corrected differential coefficient, the corrected proportional coefficient and the frequency measurement data:

[0099]

[0100] In the formula, ΔP w Indicates the change in the fan output power, that is, the output power of the fan providing frequency response; represents the modified differential coefficient of the i-th fan, It represents the correction proportional coefficient of the i-th fan, and Δf represents the frequency change, that is, the difference between the current frequency value of the system and the rated frequency value of the system.

[0101] Generally speaking, the response time scale to the frequency change rate is shorter, while the response time scale to the frequency deviation is relatively long. According to equations (8) and (10), when the wind turbine is at a lower wind speed, its rotor energy margin is less and the frequency modulation response time it can provide is short. At this time, a i Larger and b i The fan is more sensitive to the frequency change rate and mainly provides short-term power support when the frequency drops rapidly. When the fan is at a higher wind speed, a i Smaller and iThe larger the frequency, the more sensitive the wind turbine is to frequency deviation, and can provide power support for a relatively longer time; the proposed strategy makes the frequency regulation capability of the wind turbine at the current moment more matched with the frequency inertia support provided.

[0102] S5, please refer to Figure 3 , according to the wind turbine output power change and current output power, the wind turbine output power control target is obtained, that is, P ref =P w0 +ΔP w After wind and energy storage provide frequency response, further control methods are determined based on the real-time frequency changes of the power system.

[0103] Depending on whether the current frequency is higher than the frequency threshold, if so, the wind turbine returns to the MPPT operating state, and the energy storage system provides frequency support alone until the end of this frequency modulation phase; if not, the kinetic energy of the wind turbine unit continues to be released until the current frequency reaches the frequency threshold, or the wind turbine speed reaches the lower limit. Since energy storage frequency modulation control participates in the entire frequency response process, and fan frequency modulation control is only activated when the energy storage discharge power reaches the upper limit, and the system frequency deviation or frequency drop rate is still greater than a certain threshold, the fan frequency modulation control is not involved in the entire process.

[0104] In an alternative embodiment, please refer to Figure 4 as well as Figure 5 The above method is implemented by a system including a frequency detection device, a wind-storage coordinated frequency controller, an energy storage frequency controller, a wind turbine frequency controller, a wind speed detection device, an adaptive parameter calculator and a power control device. The specific operation process of the system is as follows:

[0105] The station-level frequency detection device detects the system frequency. When it detects that the system frequency drops and is below the frequency regulation dead zone, it sends a frequency control command to the wind-storage coordinated frequency controller. The wind-storage coordinated frequency controller directly sends a frequency response command to the energy storage frequency controller, and sends a pre-control command to the wind turbine frequency controller. At this time, the energy storage frequency controller responds to the system frequency based on the conventional frequency control strategy; the wind turbine frequency controller sequentially uses the wind speed detection device and the adaptive parameter calculator to control the system frequency.

[0106] When the frequency modulation power of the energy storage system reaches the upper limit, and the system frequency deviation or frequency drop rate is still greater than a certain threshold, the energy storage frequency controller sends a frequency response instruction (carrying the basic output power P w0 ). At this time, the fan frequency controller determines the frequency response output power ΔP of the fan through adaptive control parameters. w and the wind turbine final output power target value P ref , and complete this round of frequency response according to the system frequency changes.

[0107] Embodiment 2

[0108] This embodiment provides a specific application scenario to verify the above method; taking the offshore wind power wind-storage combined transmission system as an example, its complete structure diagram is as follows Figure 6 As shown, the offshore wind farm is connected to the offshore booster station through the AC submarine cable, and then connected to the onshore power grid through the flexible DC system, and the energy storage system is directly connected to the onshore power grid.

[0109] Please refer to Figure 7 , which shows the power margin and energy margin of the power wind turbine in Example 1 as the wind speed changes; wherein, the power margin shows a downward trend as the wind speed increases, and reaches the minimum at the rated wind speed; the energy margin shows an upward trend as the wind speed increases, and reaches the maximum value when the rated wind speed is reached. According to the above properties, a wind-storage combined system is designed, and three equivalent wind turbines are set to constant wind speed models of 6.5m / s, 10.4m / s, and 13m / s respectively to simulate wind turbines in low, medium, and high wind speed zones. The method for optimizing virtual inertia involved in Example 1 is involved in the simulation experiment of frequency modulation response. At 500s in the simulation experiment, a frequency drop event occurs, and the auxiliary frequency modulation power output by the three wind turbines is recorded;

[0110] The simulation waveform is as follows Figure 8 As shown in the figure, it shows that with the increase of wind speed, the short-term high-power support capability of the wind turbine decreases, but the output power of the auxiliary frequency regulation capability will increase in steady state. It can be obtained that the wind turbine in the low wind speed zone is suitable for participating in the inertia response link, the wind turbine in the high wind speed zone is suitable for participating in the long-term primary frequency regulation link, and the wind turbine in the medium wind speed zone has both high inertia support and primary frequency regulation capabilities and can participate in the entire frequency regulation process.

[0111] at the same time, Fig. 9 The diagram is the system frequency response diagram under different strategies. The figure shows that compared with the traditional wind-storage control strategy with unified control parameters, the proposed wind-storage frequency regulation strategy has a lower initial change rate of system frequency, an higher minimum point of frequency drop, and a lower steady-state frequency difference, and has a better auxiliary frequency regulation effect.

[0112] Embodiment 3

[0113] Please refer to Fig.10 A frequency control device for a combined wind turbine and energy storage device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, each step in a frequency control method for a combined wind turbine and energy storage device as described in Example 1 is implemented.

[0114] In summary, the frequency control method and device for wind turbine and energy storage provided by the present invention, by analyzing the frequency response characteristics of wind turbine and energy storage system, utilizing the characteristics of fast response speed and stable output power of energy storage system and strong short-term support capacity of wind turbine, and taking the idea of ​​giving priority to dispatching energy storage system as main wind turbine to assist frequency modulation as auxiliary, greatly improves the utilization rate of energy storage system, reduces the operation frequency and wind abandonment rate of wind turbine, and improves the economic benefits of wind-storage combined system. At the same time, in the process of wind turbine frequency modulation, by dividing the wind turbine speed into three wind speed zones according to the mapping relationship of wind speed, and designing two indicators of wind turbine power margin and energy margin according to constraint conditions, the frequency modulation capability of each wind turbine in the current wind speed zone is evaluated based on the two indicators, and the wind turbine virtual inertia control parameter adaptive setting method is designed based on this, so that each wind turbine can maximize its participation in the frequency response process according to the current state.

[0115] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A frequency control method for a wind turbine combined with energy storage, characterized in that: include: Obtaining system frequency, wind turbine unit data and energy storage data; the wind turbine unit data includes the current rotor speed, rated speed, moment of inertia, and maximum wind energy tracking coefficient; The wind turbine power margin is calculated according to the current rotation speed of the rotor and the maximum wind energy tracking coefficient, and the wind turbine energy margin is calculated according to the current rotation speed, rated rotation speed and moment of inertia of the rotor; Calculating a frequency response adaptive control coefficient of the fan according to the power margin and the energy margin; When the system frequency drops, the energy storage and the wind turbine provide a frequency response mode according to the frequency drop condition, and the frequency response power of the wind turbine is obtained according to the frequency response adaptive control coefficient; The frequency response adaptive control coefficient includes a modified differential coefficient and a modified proportional coefficient; The output power variation of the fan frequency response is obtained according to the modified differential coefficient, modified proportional coefficient and frequency variation: ； In the formula, represents the virtual inertia control coefficient, represents the modified differential coefficient of the i-th fan, represents the correction proportional coefficient of the i-th fan, Indicates the frequency change.

2. A frequency control method for a wind turbine combined with energy storage according to claim 1, characterized in that: The specific way in which energy storage and wind turbines provide frequency response is as follows: The system frequency is monitored in real time. If the system frequency is lower than the frequency modulation dead zone, the energy storage is used to provide frequency response first. If the energy storage discharge power reaches the upper limit, and the system frequency deviation or frequency drop rate is greater than a preset threshold, an action signal is sent to the fan to start the fan frequency response; After the fan receives the action signal, it calculates the power margin and energy margin of the fan based on the current state of the fan, and calculates the adaptive control coefficient to control the frequency response power of the fan; The frequency response process ends according to the system frequency recovery situation.

3. A frequency control method for wind turbine combined with energy storage according to claim 1, characterized in that: The power margin of the fan is calculated as follows: The power margin is calculated based on the current rotor speed and the maximum wind energy tracking coefficient: ； In the formula, is the maximum wind energy tracking coefficient of the i-th wind turbine, is the rotor speed of the i-th fan at the current moment, is the maximum output power of the fan, is the power margin of the i-th wind turbine at the current moment.

4. A frequency control method for wind turbine combined with energy storage according to claim 1, characterized in that: The energy margin of the fan is calculated as follows: The energy margin is calculated based on the current speed, rated speed and moment of inertia of the fan rotor: ； In the formula, is the fan's moment of inertia coefficient, Rated speed; is the rotor speed of the i-th fan at the current moment, is the energy margin of the i-th wind turbine.

5. A frequency control method for wind turbine combined with energy storage according to claim 1, characterized in that: The frequency response adaptive control coefficient of the wind turbine is calculated according to the power margin and the energy margin, specifically: The differential coefficient of the virtual inertia control of the fan is calculated according to the rotational inertia coefficient and the rated speed, and the proportional coefficient of the primary frequency modulation control of the fan is calculated according to the maximum output power, rated frequency and the differential coefficient of the fan; Correcting the differential coefficient by the power margin to obtain a corrected differential coefficient, and correcting the proportional coefficient by the energy margin to obtain a corrected proportional coefficient; The differential coefficient is: ； In the formula, represents the differential coefficient of the i-th fan, is the fan's moment of inertia coefficient, Rated speed; The differential coefficient is corrected by the power margin to obtain a corrected differential coefficient: ； In the formula, represents the modified differential coefficient, is the power margin of the i-th wind turbine at the current moment; The proportionality factor is: ； In the formula, represents the proportional coefficient of the i-th fan, Indicates the maximum output power of the fan. Indicates rated power, Indicates the adjustment coefficient; The proportional coefficient is corrected by the energy margin to obtain the corrected proportional coefficient: ； In the formula, represents the correction proportional coefficient, is the energy margin of the i-th wind turbine at the current moment.

6. A frequency control device for a wind turbine combined with energy storage, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, each step of the frequency control method for combining a wind turbine and energy storage is implemented as described in any one of claims 1-5.

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