CN113394827A - Wind power frequency modulation control method suitable for high wind power permeability level - Google Patents
Wind power frequency modulation control method suitable for high wind power permeability level Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
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- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
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Abstract
The invention provides a wind power frequency modulation control method suitable for high wind power permeability level, which relates to the field of wind power generation grid connection and comprises the following steps: monitoring the frequency of a power grid in real time, calculating the instantaneous frequency of the power grid, and when the frequency deviation of the power grid exceeds a set dead zone range due to disturbance of a power system; measuring the rotational speed of the fan and the rotational speed of the rotor of the fanω rGreater than the minimum allowable speedω minWhen the double-fed wind turbine generator system is started, the double-fed wind turbine generator system virtual inertia control module is started, and the fan actively participates in frequency modulation; calculating the active increment of the wind turbine generator; calculating an equivalent active power increment of a time domain; calculating an active power reference value of the fan; elapsed time deltatThen, the active power output of the fan is smoothly switched to the maximum power tracking output power; the rotation speed gradually returns to the initial state. The method is characterized in that a virtual inertia control link is added to a converter controller at the rotor side of the wind turbine generator, and when the frequency of a power grid is out of limit due to disturbance, the wind turbine generator is used forThe rotor rapid throughput kinetic energy participates in the frequency modulation of the power system, the frequency modulation response is faster, and the effect is better.
Description
Technical Field
The invention relates to the field of wind power generation grid connection, in particular to a wind power frequency modulation control method suitable for high wind power permeability level.
Background
With the urgent need for the reserves of non-renewable energy resources such as petroleum and the increasing deterioration of environmental problems, in recent years, new energy power generation is rapidly developed by virtue of the advantages of cleanness, low carbon, high efficiency and the like, the traditional thermal power is gradually replaced, and the architecture of the power system in China is gradually changed to a novel power system mainly comprising new energy resources. The double-fed wind turbine generator system has the advantages of active and reactive decoupling control, maximum power tracking control, small size and the like, and is connected to the grid by virtue of a power electronic converter, so that the rotor rotating speed and the grid frequency are decoupled, the advantage that the fan has rich rotating kinetic energy is hidden, and the fan does not have frequency response capability. In addition, the doubly-fed wind turbine is usually operated in a maximum power tracking mode, and cannot provide active backup for a power system. With the continuous increase of the penetration level of the wind power, the stability of the grid frequency is bound to face a huge challenge.
At present, aiming at the problem of how to ensure the frequency stability of a power system after large-scale wind power integration, the active participation of a fan in power grid frequency modulation is realized mainly by means of an additional control link. The most common virtual inertia control method includes virtual inertia control, droop control, and step virtual inertia control. The fan simulates the inertia response and the primary frequency modulation characteristic of the synchronous generator through virtual inertia and droop control; step virtual inertia control participates in system frequency modulation by means of rotor fast throughput kinetic energy, compared with the former two control strategies, the frequency modulation response is faster, the frequency modulation effect is better, however, the rotation speed recovery after the frequency response is accompanied with active sudden change, the secondary impact phenomenon to the power grid frequency still generally exists, especially under the high wind power permeation level, the fan rotation speed recovery can cause the bigger active shortage of the power grid, and more serious secondary frequency drop is caused. In order to relieve the secondary impact of the fan rotating speed recovery on the power grid frequency, the existing wind turbine generator rotating speed recovery strategy adopts a constant power method, the rotating speed recovery is driven by a small amount of active load shedding, but the secondary frequency falling degree and the rotating speed recovery time cannot be considered at the same time: the difference between the output electromagnetic power and the input mechanical power of the fan is small due to the excessively small active power load reduction, and the recovery of the rotating speed of the rotor is slowed down; on the contrary, the excessive active power load reduction can cause the instantaneous drop of the active power of the system, so that the secondary drop of the power grid frequency occurs, and in a high wind power grid-connected power system, the secondary frequency drop is even lower than the primary frequency drop. In summary, how to eliminate the problem of secondary frequency drop caused by the recovery of the rotating speed of the wind turbine generator after frequency response is urgently needed to be solved.
Disclosure of Invention
The invention provides a wind power frequency modulation control method suitable for a high wind power permeability level, and aims to solve the problem of secondary frequency drop caused by the recovery of the rotating speed of a wind turbine generator after frequency response in the prior art.
In order to solve the technical problems, the invention provides a wind power frequency modulation control method suitable for high wind power penetration level, which is characterized by comprising the following steps: comprises the following steps:
s1: monitoring the power grid frequency in real time, calculating the instantaneous power grid frequency, and executing the step S2 when the power grid frequency deviation exceeds the set dead zone range due to the disturbance of the power system;
s2: measuring the rotational speed of fan, and measuring the rotational speed omega of rotorrGreater than the minimum permissible speed ωminWhen the double-fed wind turbine generator system is started, the double-fed wind turbine generator system virtual inertia control module is started, and the fan actively participates in frequency modulation;
s3: starting a virtual inertia control module of the doubly-fed wind turbine generator;
s4: calculating the active increment of the wind turbine generator;
s5: calculating an equivalent active power increment of a time domain;
s6: calculating an active power reference value of the fan;
after the time delta t, the active power output of the fan is smoothly switched to the maximum power tracking output power; the rotation speed gradually returns to the initial state.
Preferably, the dead zone range is 49.98Hz-50.02 Hz.
Preferably, the step S3 isCollecting the rotation speed of the rotor of the fan at the disturbance moment, and calculating the maximum output power P under the protection of the torque limit of the fan corresponding to the rotation speedTlim(ω0) And maximum power tracking output power PMPPT(ω0) The calculation formula is as follows:
PTlim(ω0)＝Tlimω0 (1)
wherein in the formula (1) and the formula (2), ω is0The rotating speed of the fan rotor corresponding to the disturbance occurrence moment; t islimFor torque protection limit value, kgA constant is calculated for one of the characteristic parameters of the fan.
Preferably, said T islimThe value is 1.07 pu; k isgThe value is 0.512.
Preferably, the calculation formula in S4 is as follows:
ΔPDFIG＝PTlim(ω0)-PMPPT(ω0) (3)
in the formula (3), Δ PDFIGAnd the active variable quantity of the double-fed wind turbine generator participating in system frequency modulation is obtained.
Preferably, in S5, the calculated active power variation of the fan is coupled with time by means of a first decreasing function with respect to time, so as to obtain an equivalent active power increase Δ P in a time domain, where the calculation formula is as follows:
in the formula (4), t0Is the disturbance occurrence time; and delta t is the duration of the grid frequency support phase.
Preferably, in S6, the active power reference value of the wind turbine set is obtained by superimposing the calculated active increase to the maximum power tracking output power of the doubly-fed wind turbine, and the calculation formula is as follows:
in the formula (5), PMPPTThe output power is tracked for maximum power.
The invention has the following beneficial effects:
(1) according to the invention, a virtual inertia control link is added to a converter controller at the rotor side of the wind turbine generator, when the frequency of a power grid is out of limit due to disturbance, the power can participate in the frequency modulation of a power system by means of the fast throughput of the rotor of the wind turbine generator, the frequency modulation response is faster, and the effect is better;
(2) in the power grid frequency supporting stage, the power function based on the torque limit is a function related to time and rotating speed, and on the premise that the fan releases the same energy, the fan can provide more power supports in the disturbance initial stage, so that the lowest point of the system frequency is further improved, and the rotating speed recovery can be started earlier;
(3) the invention starts the rotation speed recovery at the moment when the fan starts the virtual inertia response, and enables the active power increment of the fan to be smoothly reduced to zero within the set time by means of the time-varying power function on the premise that the rotation speed of the fan is recovered to the initial state at the same time, so that the active power output of the fan is smoothly reduced and recovered to the maximum power tracking mode, thereby realizing the smooth recovery of the rotation speed while eliminating the secondary frequency drop, and in addition, the negative influence of mechanical fatigue on the fan body is reduced to a certain extent.
(4) The simulation verifies that the frequency response capability of the wind generating set can be further optimized under various wind power penetration levels by adopting the method, the lowest point of the power grid frequency is improved, and meanwhile, the simulation also verifies that the problems of secondary drop of the power grid frequency and mechanical fatigue in the rotating speed recovery process of the wind generating set can be eliminated by adopting the method.
Drawings
FIG. 1 is a flow chart of a wind power frequency modulation control method suitable for high wind power penetration level according to the present invention;
FIG. 2 is a schematic diagram of a change trajectory curve of active power of a doubly-fed wind turbine in a rotating speed domain according to the invention;
FIG. 3 is a schematic diagram of a simulation model according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a double-fed wind turbine generator according to an embodiment of the present invention;
fig. 5 is a simulation result of the embodiment of the present invention when the wind power permeability is 20%, where (a) is a power grid frequency change curve, (b) is a doubly-fed fan active power output change curve, (c) is a doubly-fed fan rotation speed change curve, (d) is a fan active increment change curve in the optimization method, (e) is a change curve of a difference between the torques of the high-speed shaft and the low-speed shaft of the fan, and (f) is a doubly-fed fan active power output change curve in the rotation speed domain;
fig. 6 is a simulation result of the embodiment of the present invention when the wind power permeability is 40%, where fig. (a) is a power grid frequency change curve, fig. (b) is a doubly-fed fan active output change curve, fig. (c) is a doubly-fed fan rotation speed change curve, and fig. (d) is a fan active increment change curve in the optimization method.
Detailed Description
The noun explains:
a phase-locked loop: a negative feedback control system for tuning a voltage controlled oscillator to generate a target frequency using a voltage generated by phase synchronization.
The symbols in the examples represent:
in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments.
When the frequency of a power grid exceeds a dead zone due to disturbance, a wind turbine generator set provides inertia response by increasing active power to the maximum active output under a torque limit, and the rotating speed is recovered by means of a time-varying power function.
Referring to fig. 1, the specific process is as follows:
s1: monitoring the power grid frequency in real time, calculating the instantaneous frequency of the power grid by using a phase-locked loop, executing the step S2 when the power grid frequency deviation exceeds the set dead zone range due to the disturbance of the power system, and otherwise, repeating the step S1;
in one embodiment, the dead band range is 49.98Hz to 50.02Hz, and therefore, when the grid frequency deviation is equal to or less than 49.98Hz, step S2 is performed.
S2: measuring the rotational speed of the fan rotor at a speed omegarGreater than minimum speed omegaminWhen the double-fed wind turbine generator system is started, the double-fed wind turbine generator system virtual inertia control module is started, and the fan actively participates in frequency modulation; otherwise, the fan does not participate in system frequency modulation;
s3: starting a virtual inertia control module of the doubly-fed wind turbine generator:
specifically, the rotating speed of the fan rotor at the disturbance moment is collected, and the maximum output power P under the protection of the fan torque limit corresponding to the rotating speed is calculatedTlim(ω0) And maximum power tracking output power PMPPT(ω0) The calculation formula is as follows:
PTlim(ω0)＝Tlimω0 (1)
in the above formulas (1) and (2), ω is0The rotating speed of the fan rotor corresponding to the disturbance occurrence moment; t islimFor the torque protection limit value, in one embodiment, TlimThe value is 1.07 pu; k is a radical ofgFor a calculation constant relating to a characteristic parameter of the fan, k is, in one embodimentgThe value is 0.512; and the maximum allowable output of the fan is equal to the maximum power corresponding to the torque protection limit, so that the safety and the stability of the double-fed fan are ensured, and the safety of the fan body is protected.
When the frequency of the power grid is out of limit due to disturbanceIn the method, the active power of the doubly-fed wind turbine is tracked by the maximum power of the disturbance front wind turbine to output power PMPPT(ω0) Maximum output power P added to torque limit protectionTlim(ω0) Thereby more kinetic energy of the rotor is released into the power grid, and the lowest point of the frequency is effectively improved.
S4: calculating the active increment delta P of the wind turbine generatorDFIG，
In one embodiment, the active variation of the wind turbine generator participating in the frequency modulation of the power system is calculated based on the formula in S3, where the calculation formula is as follows:
ΔPDFIG＝PTlim(ω0)-PMPPT(ω0) (3)
in the above formula (3), Δ PDFIGAnd the active variable quantity of the double-fed wind turbine generator participating in system frequency modulation is obtained.
S5: calculating an equivalent active power increment delta P of a time domain;
in one embodiment, the calculated active variation Δ P of the fan is calculated by means of a decreasing function with respect to timeDFIGCoupling with time to obtain an equivalent active power increment delta P of a time domain;
the calculation formula is as follows:
in the above formula (4), t0Is the disturbance occurrence time; and delta t is the duration of the grid frequency support phase.
In general, before the secondary frequency response is started, the rotation speed of the fan is restored to the initial state, and considering that the starting time of the secondary frequency of the system is about 20-30s after disturbance, the value of Δ t in the application is 26 s.
S6: calculating an active power reference value of the fan:
in an embodiment, the calculated active power variation Δ P is superimposed on the maximum power tracking output power of the doubly-fed wind turbine to obtain an active power reference value of the wind turbine, and a calculation formula is as follows:
in the above formula (5), PMPPTThe output power is tracked for maximum power. And, calculating the effective power reference value P of the fanrefIn order to prevent overloading of the fan and to reduce mechanical fatigue, the active power reference value P is calculatedrefIt is limited by the active power rate of change and the maximum active power limiter.
After the fan starts the virtual inertia response, the active increment of the fan is gradually reduced to zero within the set time through the decreasing function about the time in the formula (4), so that the active output of the fan is smoothly reduced and recovered to the maximum power tracking state, namely the active output of the fan is smoothly switched to PMPPTThe rotating speed is gradually restored to the initial state, and meanwhile, the secondary frequency drop is eliminated, and the mechanical fatigue problem is relieved to a certain extent.
Referring to fig. 2, fig. 2 is a schematic diagram of a power variation trajectory curve of a doubly-fed wind turbine in the application speed domain, and a process of the wind turbine participating in frequency modulation of the power system is shown as an a-B-C-D-a curve in fig. 2. When the frequency of the power grid is normal, the double-fed fan works in the maximum power tracking mode, and the active output of the double-fed fan is the maximum power tracking power PMPPT(ω0) Corresponding to point a in fig. 2; when the frequency drops and exceeds the dead zone due to the disturbance of the power grid, the virtual inertia control of the fan is started, the active output of the double-fed fan is increased to the maximum active power P under the torque limitTlim(ω0) (corresponding to the A-B stage), thereby releasing more rotor kinetic energy into the power grid, effectively raising the lowest point of frequency; as the active power of the fan is a function of time and rotating speed, the active power of the fan is smoothly reduced and recovered to a maximum power tracking mode (corresponding to a B-C-D stage) along with the change of the time and the rotating speed, and then the active power of the fan is recovered to a state before disturbance along a maximum power tracking curve, so that the rotating speed is smoothly recovered, and secondary frequency drop is eliminated.
The beneficial effects of the invention are explained in detail in the following by combining specific simulation examples.
According to the wind turbine rotor frequency response control method and device, the virtual inertia control loop is added in the rotor side converter controller, the frequency response service is rapidly provided by means of the advantage of the rapid handling function of the wind turbine rotor, and the lowest point of the power grid frequency is improved.
Referring to fig. 3, in order to verify the rationality and effectiveness of the wind power frequency modulation control method suitable for the high wind penetration level provided by the application, the application builds a power system model with different wind power permeabilities by means of an EMTP-RV software platform. The system comprises 4 synchronous generator sets, 1 asynchronous motor, a dead load with the capacity of 240MW and an aggregated wind power plant. The structural schematic diagram of the doubly-fed wind generating set is shown in fig. 4.
According to the method, when the wind speed is 9m/s and the synchronous unit is off-line at 120MW, the frequency modulation characteristics of the doubly-fed wind turbine under the following three control strategies are compared and analyzed under the scenes that the wind power permeability is 20% and 40% respectively.
(1) Maximum power tracking control (MPPT);
(2) constant power speed recovery strategy (existing method);
(3) the method is suitable for a frequency modulation strategy (optimization method) with high wind power penetration level.
For better analytical comparison with the prior art methods, the experiments were set up with: in the existing method and the optimization method, the double-fed fan releases the same rotor kinetic energy to participate in the frequency adjustment of the power grid; and in the two methods, the rotating speed of the fan is recovered to the initial state at the same time. And debugging to obtain that in the simulation analysis, the frequency support duration time delta t of the optimization method is set to be 26s, and the active power reduction amount of the rotation speed recovery stage of the existing method is set to be 0.15 pu.
When the wind power permeability is 20%, the 4 th synchronous unit is set to be offline in 40s, the active power loss of the power system is 120MW, and the frequency of the power grid drops. As can be seen from fig. 5(a), when the doubly-fed wind turbine generator employs maximum power tracking control, the doubly-fed wind turbine generator does not participate in grid frequency modulation, the active power output and the rotating speed of the doubly-fed wind turbine generator remain unchanged, and the maximum deviation of the grid frequency is 0.806 Hz. When the existing method is adopted, the maximum frequency deviation of the power grid is reduced to 0.578Hz, and the main reason is that the fan releases certain rotation kinetic energy to the power grid, and the active power output of the fan is increased from 63MW to 108 MW. Compared with the existing method, when the optimization method is adopted, the maximum frequency deviation of the power grid is further reduced to 0.566Hz and improved by 0.012Hz, which is mainly because the optimization method releases more active power in the early period of disturbance, as shown in FIGS. 5(b) and 5 (f).
As can be seen from fig. 5(c), in the early period of disturbance, the fan speed is reduced more rapidly in the optimization method, and the speed recovery is started at 53 s; because the rotating speed of the existing method is slowly converged, the rotating speed recovery is started only at 60s, and the rotating speeds of the two methods are recovered to the state before disturbance at 116 s. In addition, the existing method adopts a constant-power rotating speed recovery strategy, and the load is reduced by 20MW successfully at 60s, so that the frequency of the power grid falls for the second time, and the fall value is 0.466 Hz; and by means of the optimization method, the active power output of the double-fed fan is smoothly reduced along with time by means of a time-varying power function and is restored to a maximum power tracking mode, and secondary frequency drop is effectively eliminated.
As can be seen from fig. 5(e), in the initial stage of disturbance, due to the rapid increase of the active power of the fan in the existing method and the optimization method, both methods inevitably generate similar mechanical problems, however, the change of the fan torque in the optimization method is smooth in the process of rotating speed recovery, and the mechanical fatigue problem caused by the active sudden change of the fan is improved to a certain extent.
When the wind power permeability is increased to 40%, as can be seen from fig. 6(a) and 6(b), in the conventional method, the first drop value of the grid frequency is 0.963Hz, and the second drop value is 1.082Hz, so that the maximum deviation of the grid frequency is 1.082 Hz. Compared with the result that the wind power permeability is 20%, the secondary frequency drop is more serious, and the main reason is that under the wind power permeability of 40%, the active load reduction amount for driving the rotation speed to recover is 41MW, which is obviously higher than the active load reduction amount with the permeability of 20%. In addition, when the double-fed fan adopts an optimization method, the maximum deviation of the power grid frequency is 0.942Hz, the method is improved by 0.140Hz compared with the prior method, the frequency curve changes smoothly, and no obvious frequency secondary drop exists, which is mainly because the optimization method smoothes active sudden change in the rotating speed recovery stage by means of a time-varying power function.
The simulation result shows that with the continuous improvement of the wind power permeation level, particularly under the scene that the wind power generation permeability is 40%, the frequency secondary dropping phenomenon of the existing method is very serious and is far lower than the frequency primary dropping phenomenon. In addition, on the premise that the fans release the same energy and the rotor speed recovery time is the same: the method provided by the invention can effectively solve the problem of frequency stability of the power system under high wind power permeability, further improve the lowest point of frequency, simultaneously eliminate secondary frequency drop in the process of recovering the rotating speed of the fan and reduce the mechanical fatigue of the fan.
According to the wind power frequency modulation control method suitable for the high wind power permeability level, the existing fan rotating speed recovery method is improved, more power supports are provided for the fan at the initial disturbance stage by means of the optimized power function based on the torque limit, the lowest point of frequency is improved, and the rotating speed recovery is started earlier; and secondly, the rotation speed is recovered by a time-varying power function, the active power output of the fan is smoothly reduced and recovered to a maximum power tracking mode, the secondary frequency drop caused by the active power mutation of the fan in the rotation speed recovery process is effectively eliminated, and the mechanical fatigue problem of the fan during the rotation speed recovery period is reduced to a certain extent.
The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (7)
1. A wind power frequency modulation control method suitable for high wind power permeability level is characterized by comprising the following steps: comprises the following steps:
s1: monitoring the power grid frequency in real time, calculating the instantaneous power grid frequency, and executing the step S2 when the power grid frequency deviation exceeds the set dead zone range due to the disturbance of the power system;
s2: measuring the rotational speed of fan, and measuring the rotational speed omega of rotorrGreater than the minimum permissible speed ωminIn time, starting the virtual inertia control of the doubly-fed wind turbineThe system module is used for actively participating in frequency modulation by the fan;
s3: starting a virtual inertia control module of the doubly-fed wind turbine generator;
s4: calculating the active increment of the wind turbine generator;
s5: calculating an equivalent active power increment of a time domain;
s6: calculating an active power reference value of the fan;
after the time delta t, the active power output of the fan is smoothly switched to the maximum power tracking output power; the rotation speed gradually returns to the initial state.
2. The wind power frequency modulation control method suitable for high wind power penetration level according to claim 1, characterized in that: the dead zone range is 49.98Hz-50.02 Hz.
3. The wind power frequency modulation control method suitable for high wind power penetration level according to claim 1, characterized in that: and S3, collecting the rotating speed of the fan rotor at the disturbance moment, and calculating the maximum output power P under the protection of the fan torque limit corresponding to the rotating speedTlim(ω0) And maximum power tracking output power PMPPT(ω0) The calculation formula is as follows:
PTlim(ω0)＝Tlimω0 (1)
wherein in the formula (1) and the formula (2), ω is0The rotating speed of the fan rotor corresponding to the disturbance occurrence moment; t islimFor torque protection limit value, kgA constant is calculated for one of the characteristic parameters of the fan.
4. The wind power frequency modulation control method suitable for high wind power penetration level according to claim 3, characterized in that: the T islimThe value is 1.07 pu; k isgThe value is 0.512.
5. The wind power frequency modulation control method suitable for high wind power penetration level according to claim 1, characterized in that: the calculation formula in S4 is as follows:
ΔPDFIG＝PTlim(ω0)-PMPPT(ω0) (3)
in the formula (3), Δ PDFIGAnd the active variable quantity of the double-fed wind turbine generator participating in system frequency modulation is obtained.
6. The wind power frequency modulation control method suitable for high wind power penetration level according to claim 1, characterized in that: in S5, the calculated active power variation of the fan is coupled with time by using a first decreasing function with respect to time, so as to obtain an equivalent active power increase Δ P in a time domain, where the calculation formula is as follows:
in the formula (4), t0Is the disturbance occurrence time; and delta t is the duration of the grid frequency support phase.
7. The wind power frequency modulation control method suitable for high wind power penetration level according to claim 1, characterized in that: in the step S6, the active power reference value of the wind turbine set is obtained by superimposing the calculated active increase to the maximum power tracking output power of the doubly-fed wind turbine, and the calculation formula is as follows:
in the formula (5), PMPPTThe output power is tracked for maximum power.
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