Wind turbine generator active frequency support control method and device based on disturbance level

Abstract

The invention discloses a disturbance level-based active frequency support control method and device for a wind turbine generator. The method comprises the following steps: S1, constructing a system frequency response model considering the frequency modulation response of a grid-following type wind turbine generator; s2, determining identification thresholds of frequency disturbance levels of different degrees through the system frequency response model in combination with operation parameters of the power system; s3, based on the identification threshold values, according to the maximum frequency change rate when the power disturbance occurs to the system, the disturbance degree grade of the system under the current disturbance is judged; and S4, selecting a corresponding control strategy to participate in system frequency modulation according to the current disturbance degree grade of the system and the operation state of the wind turbine generator, so that the wind turbine generator actively supports the system frequency. The system disturbance degree and the operation state of the wind turbine generator are comprehensively considered, the standby power and the rotor kinetic energy of the wind turbine generator are fully called, the active frequency supporting capacity of the wind turbine generator is effectively improved, the method is easy to implement in engineering, and the safety and stability of power grid operation are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of power system frequency regulation control, and in particular to a method and device for active frequency support control of a wind turbine generator set based on disturbance level. Background Art

[0002] With the large-scale grid connection of wind turbines, the proportion of traditional synchronous units has continued to decrease, and the frequency regulation capability of the power system has continued to weaken. At the same time, the uncertainty and volatility of the active output of wind turbines have significantly increased the frequency regulation pressure of the system, resulting in an increased risk of system frequency instability. In order to improve the frequency support capability of the power system and ensure the reliability of power supply to users, it is urgent to tap the potential frequency regulation resources of the power grid to participate in system frequency regulation. Among them, as one of the main power sources of the future new power system, proposing a reasonable and effective frequency regulation control strategy for wind turbines is the key to solving the system frequency problem.

[0003] At present, there have been some studies on improving the frequency regulation capability of wind turbines. For example, in some related technologies, the "Improved Wind Turbine Virtual Inertia Control Strategy Based on Torque Limit" is disclosed. This study improves the traditional virtual inertia control based on the torque limit, and provides the same frequency support effect as the traditional control under the premise of consuming less rotor kinetic energy. The frequency support efficiency and capacity of the wind turbine are improved; however, this method does not adopt load reduction standby control, and can only support the system frequency in a short period of time, and cannot continuously participate in the system frequency regulation. In other related technologies, the "Direct Drive Wind Turbine Load Reduction and Frequency Regulation Strategy Combined with Wind Speed ​​Prediction" is also disclosed. This study proposes an optimized load reduction and frequency regulation strategy based on variable load reduction rate, which improves the problems of insufficient frequency regulation power and redundant standby power of the traditional load reduction and frequency regulation control strategy, and improves the frequency regulation quality and economy of the wind turbine. Although this method can take into account the different operating states of the wind turbine, it still lacks consideration of the system disturbance conditions, and the continuous frequency regulation capability of the wind turbine needs to be further optimized. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a method and device for active frequency support control of wind turbines based on disturbance level. By comprehensively considering the system disturbance degree and the operating status of the wind turbine, the standby power and rotor kinetic energy of the wind turbine are fully called upon, thereby effectively improving the active frequency support capability of the wind turbine and being easy to implement in engineering, thereby ensuring the safe and stable operation of the power grid.

[0005] The present invention adopts the following technical solution.

[0006] In a first aspect, the present invention provides a method for active frequency support control of a wind turbine generator system based on disturbance level, the method comprising:

[0007] S1. Construct a system frequency response model that takes into account the frequency regulation response of grid-connected wind turbines;

[0008] S2. Determine identification thresholds of frequency disturbance levels of different degrees through the system frequency response model in combination with the operating parameters of the power system;

[0009] S3. Based on each of the identification thresholds, judging the disturbance level of the system under the current disturbance according to the maximum frequency change rate when the system has a power disturbance;

[0010] S4. Select a corresponding control strategy to participate in system frequency modulation according to the current disturbance level of the system and the operating status of the wind turbine generator set, so that the wind turbine generator set actively supports the system frequency.

[0011] Optionally, the constructed system frequency response model includes a frequency regulation model of a thermal power unit, a frequency regulation model of a wind power unit, and an inertia model of a thermal power unit, and the expressions thereof are as follows:

[0012]

[0013]

[0014]

[0015] Where ΔP G (s) is the frequency modulation power of thermal power units, η is the proportion of new energy in the system, K M is the mechanical advantage coefficient, F H is the work proportionality coefficient of the high-pressure steam cylinder, T R is the steam cylinder reheating time coefficient, s is the Laplace variable, R is the thermal power unit adjustment coefficient; ΔP w (s) is the frequency modulation power of wind turbine, T J is the equivalent inertia time constant of the wind turbine, K f is the active frequency modulation coefficient of the wind turbine, P 0 is the steady-state active power of the wind turbine, df / dt is the frequency change rate, Δf is the frequency deviation, and f N is the rated frequency, Δf(s) is the inertia model of the thermal power unit, ΔP L is the load active power disturbance, H is the inertia time constant of the thermal power unit, and D is the damping constant of the thermal power unit.

[0016] Optionally, determining identification thresholds for different degrees of frequency disturbance levels includes:

[0017] The frequency deviation is calculated by dynamically adjusting the power disturbance input into the system frequency response model to determine the maximum frequency deviation Δf output by the model. nadir The load active power disturbance ΔP when reaching -0.1Hz, -0.2Hz, 0.1Hz and 0.2Hz respectively L1, ΔP L2 , ΔP L3 and ΔP L4 and their corresponding maximum frequency change rate r f_1 、r f_2 、r f_3 and r f_4 .

[0018] Optionally, the disturbance degree level includes:

[0019] Mild disturbance: r f_1 ≤r f_max ≤r f_3 ;

[0020] Moderate disturbance: r f_2 ≤r f_max <r f_1 or f_3 <r f_max ≤r f_4 ;

[0021] Severe disturbance: r f_max <r f_2 or f_max >r f_4 ;

[0022] Among them, r f_max is the maximum frequency change rate of the system under the current disturbance.

[0023] Optionally, the operating status of the wind turbine generator set includes: a low wind scenario and a high wind scenario;

[0024] Among them, the wind turbine set adopts overspeed load reduction control to achieve a set proportion of load reduction, which is regarded as a low wind scene, otherwise it is a high wind scene.

[0025] Optionally, selecting a corresponding control strategy to participate in system frequency regulation according to the current disturbance level of the system and the operating state of the wind turbine generator set includes:

[0026] Under mild disturbance, within the constraint of the first frequency modulation power threshold, variable coefficient virtual inertia control and droop control strategies are used to participate in system frequency modulation.

[0027] Under moderate disturbance, the maximum coefficient virtual inertia control and droop control strategies are selected to participate in system frequency regulation within the constraint of the first frequency regulation power threshold.

[0028] In the case of severe disturbance and low wind frequency drop, the system frequency is modulated by adopting a multi-control coordination strategy of short-time additional power control, speed recovery control, MPPT operation control and maximum coefficient droop control in sequence within the constraint of the second frequency modulation power threshold;

[0029] In the case of severe disturbance and low wind frequency rise, the coordinated strategies of maximum active power down-regulation control and maximum coefficient droop control are selected within the constraints of the second frequency regulation power threshold to participate in system frequency regulation;

[0030] In the case of severe disturbance and high wind frequency drop, the coordinated strategy of MPPT operation control and maximum coefficient droop control is selected within the constraint of the first frequency regulation power threshold to participate in system frequency regulation;

[0031] In the case of severe disturbance and high wind frequency rise, the coordinated strategies of maximum active power reduction control and maximum coefficient droop control are selected in sequence to participate in system frequency regulation within the constraint of the first frequency regulation power threshold.

[0032] Optionally, the virtual inertia control and droop control strategy using variable coefficients participates in the system frequency modulation, and its equivalent inertia time constant T J and active frequency modulation coefficient K f Calculated by the following formulas:

[0033]

[0034]

[0035] Where, T J_min is the minimum value of the equivalent inertia time constant; K f_min is the minimum value of the active frequency modulation coefficient; r f_max is the maximum frequency change rate of the system under the current disturbance; K J1 and K J2 T when the frequency drops and rises respectively J Adjustment coefficient, K kf1 and K kf2 are K when the frequency drops and rises respectively f Adjustment coefficient.

[0036] Optionally, the adjustment coefficient K J1 , K J2 , K kf1 and K kf2 The calculation formulas are:

[0037]

[0038] Where, T J_max is the maximum value of the equivalent inertia time constant; K f_max is the maximum value of the active frequency modulation coefficient; r f_1 and r f_3 Corresponding to the maximum frequency deviation Δf nadir The maximum frequency change rate is achieved at -0.1Hz and 0.1Hz.

[0039] Optionally, the calculation formula of the first frequency modulation power threshold is as follows:

[0040]

[0041] Where ΔP 1 w_max is the first upper limit threshold of the frequency regulation power of the wind turbine, P 0 is the steady-state active power of the wind turbine, d is the load reduction factor of the wind turbine, and Δf is the frequency deviation.

[0042] Optionally, a calculation formula for the second frequency modulation power threshold is as follows:

[0043]

[0044] Where ΔP 2 w_max is the second upper limit threshold of the frequency regulation power of the wind turbine, P 0 is the steady-state active power of the wind turbine, d is the load reduction factor of the wind turbine, Δf is the frequency deviation, ΔP si To increase power for a short time.

[0045] Optionally, the step of using a multi-control coordination strategy of short-time additional power generation control, speed recovery control, MPPT operation control and maximum coefficient droop control to participate in system frequency modulation includes:

[0046] When the disturbance occurs, the wind turbine enters the short-term increase phase to participate in the system frequency regulation. During this phase, the rotor speed of the wind turbine is ω r Speed ​​ω from overspeed to load reduction del Start to reduce continuously until the speed drops to the set speed recovery threshold ω rc Enter the speed recovery stage;

[0047] Through the speed recovery stage, the speed is restored to the optimal speed corresponding to the current wind speed ω opt Enter the MPPT operation control stage;

[0048] When the frequency deviation is restored to -0.1Hz through the MPPT operation control stage, the maximum coefficient droop control stage is entered to perform frequency regulation until the frequency deviation is restored to the frequency regulation dead zone of the wind turbine set.

[0049] Optionally, the frequency modulation power ΔP of the wind turbine set in the short-term additional power generation control stage w1 The calculation formula is as follows:

[0050] ΔP w1 =ΔP si =K si ω opt +P0 d / (1-d)

[0051] Where ΔP si is the short-term power increase, K si is the short-term power factor, ω opt is the optimal speed corresponding to the current wind speed, P 0 is the steady-state active power of the wind turbine, and d is the load reduction factor of the wind turbine.

[0052] Optionally, the frequency modulation power ΔP of the wind turbine set in the speed recovery control stage w2 The calculation formula is as follows:

[0053]

[0054] In the formula, k rc is the speed recovery coefficient, k opt is the MPPT coefficient, t rc is the time when the speed recovery starts, t is the current time, ΔP si is the short-term power increase, ω r is the rotor speed, P 0 is the steady-state active power of the wind turbine.

[0055] Optionally, the frequency modulation power ΔP of the wind turbine set during the MPPT operation control stage w3 The calculation formula is as follows:

[0056] ΔP w3 =P 0 d / (1-d)

[0057] Where P 0 is the steady-state active power of the wind turbine, and d is the load reduction factor of the wind turbine.

[0058] Optionally, the frequency modulation power ΔP of the wind turbine set in the droop control stage of the maximum coefficient w4 The calculation formula is as follows:

[0059]

[0060] In the formula, K f_max is the maximum value of active frequency modulation coefficient, f N is the rated frequency, Δf is the frequency deviation, P 0 is the steady-state active power of the wind turbine.

[0061] Optionally, the maximum active power is reduced to control the frequency modulation power ΔP of the wind turbine group w5 The calculation formula is as follows:

[0062] ΔP w5 =-P0 d / (1-d)

[0063] Where Δf is the frequency deviation, P 0 is the steady-state active power of the wind turbine, and d is the load reduction factor of the wind turbine.

[0064] In a second aspect, the present invention provides a wind turbine active frequency support control device based on disturbance level, which runs the steps of any method described in the first aspect of the present invention, and the device includes:

[0065] Construct a frequency response model module to construct a system frequency response model that takes into account the frequency regulation response of grid-connected wind turbines;

[0066] A recognition threshold determination module is used to determine recognition thresholds of different frequency disturbance levels through the system frequency response model in combination with the operating parameters of the power system;

[0067] A disturbance level determination module, configured to determine the disturbance level of the system under the current disturbance based on the identification thresholds and the maximum frequency change rate when the system has a power disturbance;

[0068] The system frequency regulation module is used to select the corresponding control strategy to participate in the system frequency regulation according to the current disturbance level of the system and the operating status of the wind turbine generator set, so that the wind turbine generator set can actively support the system frequency.

[0069] In a third aspect, the present invention provides a terminal, including a processor and a storage medium;

[0070] The storage medium is used to store instructions;

[0071] The processor is used to operate according to the instructions to execute the steps of any one of the methods described in the first aspect of the present invention.

[0072] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods described in the first aspect of the present invention.

[0073] The beneficial effects of the present invention are as follows:

[0074] In view of the current situation that the frequency support capability of the new power system is weak and the active frequency support capability of the wind turbine has yet to be explored, the present invention comprehensively considers the different operating states of the wind turbine and the different disturbance degrees of the system, and grades the disturbance degree by establishing a system frequency response model and the maximum frequency change rate after the disturbance occurs, and then adopts different control strategies to participate in the system frequency regulation, so that the wind turbine can improve the system frequency minimum point and the system frequency change rate more finely; the present invention can fully call on the standby power and rotor kinetic energy of the wind turbine based on the actual disturbance conditions of the power grid and the operating state of the wind turbine, and effectively improve the frequency support capability of the wind turbine; at the same time, the control strategy of the present invention can be directly realized by adjusting the parameters of the existing wind turbine controller, has strong applicability, is easy to implement in engineering, and can provide technical support for the safe and stable operation of the new power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 It is a flow chart of the active frequency support control method of a wind turbine generator system based on disturbance level in the present invention;

[0076] Figure 2 It is a schematic diagram of a system frequency response model taking into account the frequency modulation response of a grid-connected wind turbine generator set in the present invention;

[0077] Figure 3 A schematic diagram of the method for selecting the active frequency support strategy of the wind turbine generator set in the present invention;

[0078] Figure 4 It is a schematic diagram of the operating state of a wind turbine in a low wind scenario, a severe disturbance and a frequency drop condition of the present invention;

[0079] Figure 5 This is a comparison diagram of simulation experiments under mild disturbance in the present invention;

[0080] Figure 6 This is a comparison diagram of simulation experiments under moderate disturbance in the present invention;

[0081] Figure 7 This is a comparison diagram of simulation experiments under moderate to severe disturbances in the present invention;

[0082] Figure 8 The figure is a structural principle block diagram of the active frequency support control device for wind turbines based on disturbance level in the present invention. DETAILED DESCRIPTION

[0083] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in the present invention are only part of the embodiments of the present invention, not all of the embodiments. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0084] Embodiment 1:

[0085] Reference Figure 1 The embodiment of the present invention provides a method for controlling active frequency support of a wind turbine generator system based on disturbance level, which specifically includes the following steps:

[0086] S1. Construct a system frequency response model that takes into account the frequency regulation response of grid-connected wind turbines;

[0087] like Figure 2 As shown, the system frequency response (SFR) model constructed in this embodiment includes the frequency regulation model of the thermal power unit, the frequency regulation model of the wind power unit and the inertia model of the thermal power unit; the expressions of these three models are shown in equations (1) to (3) respectively:

[0088]

[0089]

[0090]

[0091] Where ΔP G (s) is the frequency modulation power of thermal power units, η is the proportion of new energy in the system, K M is the mechanical advantage coefficient, F H is the work proportionality coefficient of the high-pressure steam cylinder, T R is the steam cylinder reheating time coefficient, s is the Laplace variable, R is the thermal power unit adjustment coefficient; ΔP w (s) is the frequency modulation power of wind turbine, T J is the equivalent inertia time constant of the wind turbine, K f is the active frequency modulation coefficient of the wind turbine, P 0 is the steady-state active power of the wind turbine, df / dt is the frequency change rate, Δf is the frequency deviation, and f N is the rated frequency, Δf(s) is the inertia model of the thermal power unit, ΔP L is the load active power disturbance, H is the inertia time constant of the thermal power unit, and D is the damping constant of the thermal power unit.

[0092] Among them, the wind turbine generator system adopts the control strategy proposed in this embodiment to support the system frequency.

[0093] S2. Determine identification thresholds of frequency disturbance levels of different degrees through the system frequency response model in combination with the operating parameters of the power system;

[0094] In this embodiment, after collecting the operating parameters of each node of the power system and assigning them to the system frequency response (SFR) model, the frequency deviation is calculated by dynamically adjusting the power disturbance input to the SFR model to determine the maximum frequency deviation Δf that the model outputs. nadir The load active power disturbance ΔP when reaching -0.1Hz, -0.2Hz, 0.1Hz and 0.2Hz respectively L1 , ΔP L2 , ΔP L3 and ΔP L4 and their corresponding maximum frequency change rate r f_1 、r f_2 、r f_3 and r f_4 ; The obtained r f_1 、r f_2 、r f_3 and r f_4 As the identification threshold of each disturbance level.

[0095] S3. Based on each of the identification thresholds, judging the disturbance level of the system under the current disturbance according to the maximum frequency change rate when the system has a power disturbance;

[0096] Specifically, after a power disturbance occurs in the system, the system disturbance data is obtained in real time, and the real-time maximum frequency change rate r is calculated. f_max , according to r f_max Determine the disturbance level of the system under the current disturbance; wherein the disturbance level includes:

[0097] Mild disturbance: r f_1 ≤r f_max ≤r f_3 ;

[0098] Moderate disturbance: r f_2 ≤r f_max <r f_1 or f_3 <r f_max ≤r f_4 ;

[0099] Severe disturbance: r f_max <r f_2 or f_max >r f_4 .

[0100] S4. Select a corresponding control strategy to participate in system frequency modulation according to the current disturbance level of the system and the operating status of the wind turbine generator set, so that the wind turbine generator set actively supports the system frequency.

[0101] Among them, the wind turbine adopts overspeed load reduction control to achieve a set ratio of load reduction, which is considered a low wind scene, otherwise it is a high wind scene; the set ratio in this embodiment is 10%. In the low wind scene, the wind turbine implements load reduction operation based on overspeed load reduction control, and in the high wind scene, the wind turbine implements load reduction operation based on pitch angle load reduction control;

[0102] like Figure 3 As shown, in step S4, the selection method of the wind turbine active frequency support strategy under different system disturbance levels and wind turbine operating states specifically includes:

[0103] (1) Under mild disturbance, the variable coefficient virtual inertia control and droop control strategies are selected within the constraint of the first frequency modulation power threshold to participate in system frequency modulation;

[0104] (2) Under moderate disturbance, the maximum coefficient virtual inertia control and droop control strategies are selected within the constraint of the first frequency modulation power threshold to participate in system frequency modulation;

[0105] (3) In the case of severe disturbance and low wind frequency drop, the multi-control coordination strategy of short-term additional power control, speed recovery control, MPPT operation control and maximum coefficient droop control is selected within the constraint of the second frequency regulation power threshold to participate in system frequency regulation;

[0106] (4) In the case of severe disturbance and low wind frequency rise, the coordinated strategy of maximum active power down-regulation control and maximum coefficient droop control is selected within the constraint of the second frequency regulation power threshold to participate in system frequency regulation;

[0107] (5) In the case of severe disturbance and high wind frequency drop, the coordinated strategy of MPPT operation control and maximum coefficient droop control is selected within the constraint of the first frequency regulation power threshold to participate in system frequency regulation;

[0108] (6) In the case of severe disturbance and high wind frequency rise, the coordinated strategy of maximum active power reduction control and maximum coefficient droop control is selected within the constraint of the first frequency regulation power threshold to participate in system frequency regulation.

[0109] Specifically, under mild disturbance conditions, regardless of whether the wind turbine is operating in a low wind scenario or a high wind scenario, virtual inertia control and droop control are used to participate in system frequency regulation, which can be specifically expressed by formula (4):

[0110]

[0111] Where ΔPw is the total frequency modulation power of the wind turbine; ΔP 1 and ΔP 2 are the frequency modulation power output by virtual inertia control and droop control respectively; P 0 is the steady-state active power of the wind turbine; df / dt is the frequency change rate; Δf is the frequency deviation; K 1 and K 2 are the virtual inertia coefficient and droop coefficient of the wind turbine respectively; T J is the equivalent inertia time constant of the wind turbine, K f is the active frequency regulation coefficient of the wind turbine.

[0112] Among them, under mild disturbance, when the variable coefficient virtual inertia control and droop control strategy are used to participate in the system frequency modulation, its equivalent inertia time constant T J and active frequency modulation coefficient K f Calculated by equation (5) and equation (6) respectively.

[0113]

[0114]

[0115] Where, T J_min is the minimum value of the equivalent inertia time constant, K f_min is the minimum value of the active frequency modulation coefficient; both are based on GB / T 19963.1-2021. In this embodiment, T J_min The value is 8, K f_min The value is 10; r f_max is the maximum frequency change rate of the system under the current disturbance; K J1 and K J2 T when the frequency drops and rises respectively J Adjustment coefficient, K kf1 and K kf2 are K when the frequency drops and rises respectively f The adjustment coefficient is calculated as follows:

[0116]

[0117] Where, T J_max is the maximum value of the equivalent inertia time constant, K f_max is the maximum value of the active frequency modulation coefficient, which is based on GB / T 19963.1-2021. In this embodiment, T J_max The value is 12, K f_max The value is 50; r f_1 and r f_3 Corresponding to the maximum frequency deviation Δf nadirThe maximum frequency change rate is achieved at -0.1Hz and 0.1Hz.

[0118] Under mild disturbance, the maximum frequency modulation power (first frequency modulation power threshold) of the wind turbine is calculated as follows:

[0119]

[0120] Where ΔP 1 w_max is the first upper limit threshold of the frequency regulation power of the wind turbine, P 0 is the steady-state active power of the wind turbine, d is the load reduction factor of the wind turbine, and Δf is the frequency deviation.

[0121] It is further explained that under moderate disturbance, when the maximum coefficient virtual inertia control and droop control strategy are used to participate in system frequency regulation, regardless of whether the wind turbine is operating in a low wind or high wind scenario, its equivalent inertia time constant T J and active frequency modulation coefficient K f The maximum value T J_max and K f_max , the maximum FM power is the same as formula (8).

[0122] In summary, if Figure 2 As shown in the figure, the frequency regulation model of the wind turbine can be further expressed as:

[0123]

[0124] Where ΔP w (s) is the frequency modulation power of wind turbine, T J is the equivalent inertia time constant of the wind turbine, K f is the active frequency modulation coefficient of the wind turbine, P 0 is the steady-state active power of the wind turbine, df / dt is the frequency change rate, Δf is the frequency deviation, and f N is the rated frequency, T J_max is the maximum value of the equivalent inertia time constant; K f_max It is the maximum value of the active frequency modulation coefficient.

[0125] The control strategy for severe disturbance and light wind scenarios is as follows:

[0126] A. Frequency drop condition: After the disturbance occurs, the wind turbine enters a short-term power increase stage, and the frequency modulation power ΔP w1 As shown in formula (9), the rotor speed ω of the wind turbine in this stage is r Speed ​​ω from overspeed to load reduction del Start to decrease continuously.

[0127] ΔP w1 =ΔPsi =K si ω opt +P 0 d / (1-d) (9)

[0128] Where ΔP si is the short-term power increase, K si is the short-term power factor, ω opt is the optimal speed corresponding to the current wind speed.

[0129] When the speed drops to the set speed recovery threshold ω rc (In this embodiment, ω rc When the speed is equal to 0.8 times the rated speed, it enters the speed recovery stage. At this time, the frequency modulation power of the wind turbine set ΔP w2 as follows:

[0130]

[0131] In the formula, k rc is the speed recovery coefficient, k opt is the MPPT coefficient, t rc is the time when the speed recovery starts, t is the current time, ΔP si is the short-term power increase, ω r is the rotor speed, P 0 is the steady-state active power of the wind turbine.

[0132] When the speed returns to ω opt When the wind turbine enters the MPPT (maximum power point tracking) operation stage, the frequency modulation power ΔP w3 as follows:

[0133] ΔP w3 =P 0 d / (1-d) (11)

[0134] Where P 0 is the steady-state active power of the wind turbine, and d is the load reduction factor of the wind turbine.

[0135] When the frequency deviation Δf recovers to -0.1Hz, it enters the droop control stage. At this time, the frequency modulation power ΔP of the wind turbine is w4 as follows:

[0136]

[0137] In the formula, K f_max is the maximum value of active frequency modulation coefficient, f N is the rated frequency, Δf is the frequency deviation, P 0 is the steady-state active power of the wind turbine.

[0138] The operating status of wind turbines under severe disturbance and low wind frequency drop conditions is as follows: Figure 4 As shown, where ω opt ,ω rc ,ω del They correspond to the optimal speed, speed recovery threshold, overspeed load reduction operation speed, point A is the load reduction operation point, point B is the short-time increase operation point, point C is the speed recovery start point, point D is the speed recovery middle point, and point E is the MPPT operation point. Figure 4 It can be seen that the fan starts running at point A, and the corresponding speed is ω del After the disturbance occurs, the fan operation point changes from point A to point B, and enters the short-term increase phase until the speed drops to ω rc At this time, the fan begins to enter the speed recovery stage, the speed begins to rise, and the fan operation point slowly changes from point C to point D. The fan enters the MPPT control stage. In this stage, the fan completes the transition from point D to point E, and the speed recovers to ω opt Finally, the fan operating point returns from point E to point A, and the speed becomes ω again. del , the entire frequency modulation process is completed.

[0139] B. Frequency rising condition: After the disturbance occurs, the maximum active power is reduced to control the frequency modulation power ΔP of the wind turbine group. w5 The calculation formula is as follows:

[0140] ΔP w5 =-P 0 d / (1-d) (13)

[0141] Where Δf is the frequency deviation, P 0 is the steady-state active power of the wind turbine, and d is the load reduction factor of the wind turbine.

[0142] At this time, the fan speed ω r Speed ​​ω from overspeed to load reduction del Continue to rise, if the speed reaches the upper limit ω max , then the active power output is reduced by increasing the pitch angle β. When Δf recovers to 0.1 Hz, the droop control stage is entered to perform frequency regulation until the frequency deviation is restored to the frequency regulation dead zone of the wind turbine. The calculation formula is the same as formula (12).

[0143] Under severe disturbance, the maximum frequency modulation power (second frequency modulation power threshold) of the wind turbine is calculated as follows:

[0144]

[0145] Where ΔP 2 w_max is the second upper limit threshold of the frequency regulation power of the wind turbine, P 0is the steady-state active power of the wind turbine, d is the load reduction factor of the wind turbine, Δf is the frequency deviation, ΔP si To increase power for a short time.

[0146] The control strategy in the severe disturbance and high wind scenario is as follows:

[0147] Under the condition of frequency drop, after the disturbance occurs, the frequency modulation power of the wind turbine is ΔP w1 Same as formula (11), the active power output is adjusted by pitch angle control. When Δf recovers to -0.1Hz, it enters the droop control stage, and the calculation formula is the same as formula (12); under this condition, the maximum frequency modulation power of the wind turbine is the same as formula (8).

[0148] Under the condition of frequency rise, after the disturbance occurs, the frequency modulation power of the wind turbine is ΔP w1 Same as formula (13), the active power output is adjusted by pitch angle control. When Δf recovers to 0.1Hz, it enters the droop control stage, and the calculation formula is the same as formula (12); under this condition, the maximum frequency modulation power of the wind turbine is the same as formula (8).

[0149] The effectiveness of the method of the present invention is verified by comparing the wind turbine active frequency support control method based on disturbance level provided by the present invention with the traditional method.

[0150] When the disturbance is slight, the simulation experiment comparison results of the method of the present invention with fixed parameter control and traditional adaptive control are as follows: Figure 5 As shown in (a) and (b);

[0151] When the disturbance is moderate, the simulation experiment comparison results of the method of the present invention with fixed parameter control and traditional adaptive control are as follows: Figure 6 As shown in (a) and (b);

[0152] The experimental simulation results of the method of the present invention, fixed parameter control and traditional adaptive control in different scenarios under severe disturbance are as follows: Figure 7 As shown in (a) to (f) in FIG.

[0153] It can be seen from the above simulation experimental results that, compared with the other two control methods, under different wind speed scenarios and different disturbance degrees, the lowest point of the system frequency is the highest and the frequency recovery speed is the fastest when the control method of the present invention is adopted, indicating that the control method of the present invention effectively improves the frequency regulation capability of the wind turbine.

[0154] The beneficial effects of the present invention are as follows:

[0155] In view of the current situation that the frequency support capability of the new power system is weak and the active frequency support capability of the wind turbine has yet to be explored, the present invention comprehensively considers the different operating states of the wind turbine and the different disturbance degrees of the system, and grades the disturbance degree by establishing a system frequency response model and the maximum frequency change rate after the disturbance occurs, and then adopts different control strategies to participate in the system frequency regulation, so that the wind turbine can improve the system frequency minimum point and the system frequency change rate more finely; the present invention can fully call on the standby power and rotor kinetic energy of the wind turbine based on the actual disturbance conditions of the power grid and the operating state of the wind turbine, and effectively improve the frequency support capability of the wind turbine; at the same time, the control strategy of the present invention can be directly realized by adjusting the parameters of the existing wind turbine controller, has strong applicability, is easy to implement in engineering, and can provide technical support for the safe and stable operation of the new power system.

[0156] Embodiment 2:

[0157] like Figure 8 As shown, the present invention provides a wind turbine active frequency support control device based on disturbance level, the device is used to implement the steps of the method in the above embodiment 1, and the device specifically includes:

[0158] Construct a frequency response model module to construct a system frequency response model that takes into account the frequency regulation response of grid-connected wind turbines;

[0159] A recognition threshold determination module is used to determine recognition thresholds of different frequency disturbance levels through the system frequency response model in combination with the operating parameters of the power system;

[0160] A disturbance level determination module, configured to determine the disturbance level of the system under the current disturbance based on the identification thresholds and the maximum frequency change rate when the system has a power disturbance;

[0161] The system frequency regulation module is used to select the corresponding control strategy to participate in the system frequency regulation according to the current disturbance level of the system and the operating status of the wind turbine generator set, so that the wind turbine generator set can actively support the system frequency.

[0162] The wind turbine active frequency support control device based on disturbance level provided in the embodiment of the present invention and the wind turbine active frequency support control method based on disturbance level provided in Example 1 are based on the same technical concept, and can produce the beneficial effects as described in Example 1. For the contents not described in detail in this embodiment, please refer to Example 1.

[0163] Embodiment three:

[0164] An embodiment of the present invention provides a terminal, including a processor and a storage medium;

[0165] The storage medium is used to store instructions;

[0166] The processor is used to operate according to the instruction to execute the steps of the method according to any one of the first embodiments.

[0167] Embodiment 4:

[0168] An embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the steps of any method described in Embodiment 1 are implemented.

[0169] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0170] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0171] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0172] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for active frequency support control of a wind turbine generator system based on disturbance level, characterized in that: The method includes the following steps: S1. Construct a system frequency response model that takes into account the frequency regulation response of grid-connected wind turbines; S2. Determine identification thresholds of frequency disturbance levels of different degrees through the system frequency response model in combination with the operating parameters of the power system; S3. Based on each of the identification thresholds, judging the disturbance level of the system under the current disturbance according to the maximum frequency change rate when the system has a power disturbance; S4. Select a corresponding control strategy to participate in system frequency modulation according to the current disturbance level of the system and the operating status of the wind turbine generator set, so that the wind turbine generator set actively supports the system frequency.

2. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 1, characterized in that: In step S1, the constructed system frequency response model includes the frequency regulation model of the thermal power unit, the frequency regulation model of the wind power unit and the inertia model of the thermal power unit, and the expressions thereof are as follows: In the formula, ΔP G (s) is the frequency modulation power of thermal power units, η is the proportion of new energy in the system, K M is the mechanical advantage coefficient, F H is the work proportionality coefficient of the high-pressure steam cylinder, T R is the steam cylinder reheating time coefficient, s is the Laplace variable, R is the thermal power unit adjustment coefficient; ΔP w (s) is the frequency modulation power of wind turbine, T J is the equivalent inertia time constant of the wind turbine, K f is the active frequency modulation coefficient of the wind turbine, P0 is the steady-state active power of the wind turbine, df / dt is the frequency change rate, Δf is the frequency deviation, and f N is the rated frequency, Δf(s) is the inertia model of the thermal power unit, ΔP L is the load active power disturbance, H is the inertia time constant of the thermal power unit, and D is the damping constant of the thermal power unit.

3. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 1, characterized in that: In step S2, determining the identification thresholds of different frequency disturbance levels includes: The frequency deviation is calculated by dynamically adjusting the power disturbance input into the system frequency response model to determine the maximum frequency deviation Δf output by the model. nadir The load active power disturbance ΔP when reaching -0.1Hz, -0.2Hz, 0.1Hz and 0.2Hz respectively L1 , ΔP L2 , ΔP L3 and ΔP L4 and their corresponding maximum frequency change rate r f_1 、r f_2 、r f_3 and r f_4 .

4. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 3 is characterized in that: In step S3, the disturbance degree levels include: Mild disturbance: r f_1 ≤r f_max ≤r f_3 ; Moderate disturbance: r f_2 ≤r f_max <r f_1 or f_3 <r f_max ≤r f_4 ; Severe disturbance: r f_max <r f_2 or f_max >r f_4 ; Among them, r f_max is the maximum frequency change rate of the system under the current disturbance.

5. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 4 is characterized in that: In step S4, the operating status of the wind turbine generator set includes: a low wind scene and a high wind scene; Among them, the wind turbine set adopts overspeed load reduction control to achieve a set proportion of load reduction, which is regarded as a low wind scene, otherwise it is a high wind scene.

6. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 5, characterized in that: In step S4, selecting a corresponding control strategy to participate in system frequency regulation according to the current disturbance level of the system and the operating state of the wind turbine generator set includes: Under mild disturbance, within the constraint of the first frequency modulation power threshold, variable coefficient virtual inertia control and droop control strategies are used to participate in system frequency modulation. Under moderate disturbance, the maximum coefficient virtual inertia control and droop control strategies are selected to participate in system frequency regulation within the constraint of the first frequency regulation power threshold. In the case of severe disturbance and low wind frequency drop, the system frequency is modulated by adopting a multi-control coordination strategy of short-time additional power control, speed recovery control, MPPT operation control and maximum coefficient droop control in sequence within the constraint of the second frequency modulation power threshold; In the case of severe disturbance and low wind frequency rise, the coordinated strategies of maximum active power down-regulation control and maximum coefficient droop control are selected within the constraints of the second frequency regulation power threshold to participate in system frequency regulation; In the case of severe disturbance and high wind frequency drop, the coordinated strategy of MPPT operation control and maximum coefficient droop control is selected within the constraint of the first frequency regulation power threshold to participate in system frequency regulation; In the case of severe disturbance and high wind frequency rise, the coordinated strategies of maximum active power reduction control and maximum coefficient droop control are selected in sequence to participate in system frequency regulation within the constraint of the first frequency regulation power threshold.

7. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 6, characterized in that: The virtual inertia control and droop control strategy using variable coefficients participates in the system frequency modulation, and its equivalent inertia time constant T J and active frequency modulation coefficient K f Calculated by the following formulas: Where, T J_min is the minimum value of the equivalent inertia time constant; K f_min is the minimum value of the active frequency modulation coefficient; r f_max is the maximum frequency change rate of the system under the current disturbance; K J1 and K J2 T when the frequency drops and rises respectively J Adjustment coefficient, K kf1 and K kf2 are K when the frequency drops and rises respectively f Adjustment coefficient.

8. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 7, characterized in that: The adjustment coefficient K J1 , K J2 , K kf1 and K kf2 The calculation formulas are: Where, T J_max is the maximum value of the equivalent inertia time constant; K f_max is the maximum value of the active frequency modulation coefficient; r f_1 and r f_3 Corresponding to the maximum frequency deviation Δf nadir The maximum frequency change rate is achieved at -0.1Hz and 0.1Hz.

9. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 6, characterized in that: The calculation formula of the first frequency modulation power threshold is as follows: In the formula, ΔP 1 w_max is the first upper limit threshold of the frequency modulation power of the wind turbine generator set, P0 is the steady-state active power of the wind turbine generator set, d is the load reduction factor of the wind turbine generator set, and Δf is the frequency deviation.

10. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 6, characterized in that: The calculation formula of the second frequency modulation power threshold is as follows: In the formula, ΔP 2 w_max is the second upper limit threshold of the frequency modulation power of the wind turbine, P0 is the steady-state active power of the wind turbine, d is the load reduction factor of the wind turbine, Δf is the frequency deviation, ΔP si To increase power for a short time.

11. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 6, characterized in that: The steps of participating in system frequency modulation by using a multi-control coordination strategy of short-time additional generation control, speed recovery control, MPPT operation control and maximum coefficient droop control include: When the disturbance occurs, the wind turbine enters the short-term increase phase to participate in the system frequency regulation. During this phase, the rotor speed of the wind turbine is ω r Speed ​​ω from overspeed to load reduction del Start to reduce continuously until the speed drops to the set speed recovery threshold ω rc Enter the speed recovery stage; Through the speed recovery stage, the speed is restored to the optimal speed corresponding to the current wind speed ω opt Enter the MPPT operation control stage; When the frequency deviation is restored to -0.1Hz through the MPPT operation control stage, the maximum coefficient droop control stage is entered to perform frequency regulation until the frequency deviation is restored to the frequency regulation dead zone of the wind turbine set.

12. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 11, characterized in that: The frequency modulation power ΔP of the wind turbine group in the short-term additional power generation control stage w1 The calculation formula is as follows: ΔP w1 =ΔP si =K si oh opt +P0d / (1-d) In the formula, ΔP si is the short-term power increase, K si is the short-term power factor, ω opt is the optimal speed corresponding to the current wind speed, P0 is the steady-state active power of the wind turbine, and d is the load reduction factor of the wind turbine.

13. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 11, characterized in that: The frequency modulation power ΔP of the wind turbine set in the speed recovery control stage w2 The calculation formula is as follows: In the formula, k rc is the speed recovery coefficient, k opt is the MPPT coefficient, t rc is the time when the speed recovery starts, t is the current time, ΔP si is the short-term power increase, ω r is the rotor speed, and P0 is the steady-state active power of the wind turbine.

14. The method for controlling active frequency support of a wind turbine generator system based on disturbance level according to claim 11, characterized in that: The frequency modulation power ΔP of the wind turbine set in the MPPT operation control stage w3 The calculation formula is as follows: ΔP w3 =P0d / (1-d) Where P0 is the steady-state active power of the wind turbine, and d is the load reduction factor of the wind turbine.

15. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 11, characterized in that: The frequency modulation power ΔP of the wind turbine set in the droop control stage of the maximum coefficient w4 The calculation formula is as follows: In the formula, K f_max is the maximum value of active frequency modulation coefficient, f N is the rated frequency, Δf is the frequency deviation, and P0 is the steady-state active power of the wind turbine.

16. The method for controlling active frequency support of wind turbines based on disturbance level according to claim 6, characterized in that: The maximum active power down control frequency modulation power ΔP of the wind turbine group w5 The calculation formula is as follows: ΔP w5 =-P0d / (1-d) Where Δf is the frequency deviation, P0 is the steady-state active power of the wind turbine, and d is the load reduction factor of the wind turbine.

17. A wind turbine active frequency support control device based on disturbance level, running the wind turbine active frequency support control method based on disturbance level as claimed in any one of claims 1 to 16, characterized in that: The device includes: Construct a frequency response model module to construct a system frequency response model that takes into account the frequency regulation response of grid-connected wind turbines; A recognition threshold determination module is used to determine recognition thresholds of different frequency disturbance levels through the system frequency response model in combination with the operating parameters of the power system; A disturbance level determination module, configured to determine the disturbance level of the system under the current disturbance based on the identification thresholds and the maximum frequency change rate when the system has a power disturbance; The system frequency regulation module is used to select the corresponding control strategy to participate in the system frequency regulation according to the current disturbance level of the system and the operating status of the wind turbine generator set, so that the wind turbine generator set can actively support the system frequency.

18. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1-16.

19. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 15 are implemented.

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