Primary frequency modulation control method and system for hybrid wind farm

Abstract

The application discloses a kind of primary frequency modulation control method and system of hybrid wind farm, including obtaining the data information of target power system and corresponding hybrid wind farm;Multiple-machine system frequency response model of target power system is constructed and is simplified to obtain aggregate response model;Based on the dynamic process of wind turbine output power and fan, the primary frequency modulation dynamic model of hybrid wind farm is constructed;The active output power of network type fan in hybrid wind farm is calculated;Based on the real-time rotor kinetic energy stored in each fan in hybrid wind farm, the droop coefficient of each network type fan and the frequency modulation power required to be provided by follow network type fan cluster are calculated;According to the frequency modulation characteristic parameters of follow network type fan cluster, real-time system frequency and energy state index, the output power of each follow network type fan is calculated;The primary frequency modulation control of hybrid wind farm is completed.The application not only realizes the primary frequency modulation control of hybrid wind farm, but also has higher reliability and better accuracy.

Description

Technical Field

[0001] This invention belongs to the field of electrical automation, and specifically relates to a primary frequency regulation control method and system for a hybrid wind farm. Background Technology

[0002] With economic and technological development and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and daily life, bringing endless convenience. Therefore, ensuring a stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] Currently, environmental problems are becoming increasingly serious, and more and more wind power systems are being integrated into the power grid. The impact of wind farm grid-connected operation on the frequency stability of the power system is becoming increasingly significant. Currently, wind turbine converters mainly employ two control methods: grid-following (GFL) and grid-forming (GFM). Grid-following wind turbines respond to grid frequency changes by adjusting active power, but their response depends on a locked grid voltage phase, limiting their dynamic adjustment capability during large frequency fluctuations. Grid-forming wind turbines can autonomously establish and support grid voltage and frequency, exhibiting stronger grid stability capabilities; however, they still have shortcomings in frequency regulation parameter setting and power distribution strategies, and have not yet achieved ideal regulation performance.

[0004] Existing frequency regulation strategies for wind farms typically do not adequately consider the optimal distribution of turbine rotor kinetic energy. Furthermore, current control schemes often fail to fully utilize the frequency regulation potential of wind farms, and during frequency events, some turbines may shut down due to exceeding speed limits, thus weakening the frequency regulation effect. Finally, existing schemes cannot effectively address the coordinated control issues between grid-connected and grid-connected turbines in hybrid wind farms. These shortcomings result in poor reliability and accuracy of existing primary frequency regulation control schemes for hybrid wind farms. Summary of the Invention

[0005] One of the objectives of this invention is to provide a primary frequency regulation control method for hybrid wind farms that is highly reliable and accurate.

[0006] The second objective of this invention is to provide a system for implementing the primary frequency regulation control method of the hybrid wind farm.

[0007] The primary frequency regulation control method for a hybrid wind farm provided by this invention includes the following steps:

[0008] S1. Obtain data information on the target power system and the corresponding hybrid wind farm;

[0009] S2. Based on the data obtained in step S1, construct a multi-machine system frequency response model of the target power system and simplify it to obtain a converged response model;

[0010] S3. Based on the data obtained in step S1, construct a primary frequency regulation dynamic model of the hybrid wind farm based on the wind turbine output power and the dynamic process of the wind turbine;

[0011] S4. When the frequency deviation exceeds the adjustment dead zone due to system power imbalance, calculate the active power output of the grid-type wind turbines in the hybrid wind farm based on the model constructed in steps S2 and S3.

[0012] S5. Based on the data obtained in step S4, and the real-time rotor kinetic energy stored in each wind turbine in the hybrid wind farm, calculate the sag coefficient of each grid-type wind turbine and the frequency regulation power required by the grid-type wind turbine cluster.

[0013] S6. Calculate the output power of each grid-connected wind turbine based on the frequency regulation characteristic parameters of the grid-connected wind turbine cluster, the real-time system frequency, and the energy state index;

[0014] S7. Complete the primary frequency regulation control of the hybrid wind farm.

[0015] Step S2 specifically includes the following steps:

[0016] Based on the data obtained in step S1, a multi-machine system frequency response (MM-SFR) model of the target power system is constructed; in the constructed model, the step disturbance power... The frequency deviation is obtained by subtracting the feedback signal from the first transmission module. The transfer function of the first transfer module is expressed as follows: , The normalized inertial constant of the thermal power generating unit. The normalized damping constant of the thermal power generating unit; frequency deviation Feedback signals are obtained through feedback loops; each of the m thermal power units and n wind power units in the target power system is modeled as a feedback loop; the feedback loop corresponding to the m-th thermal power unit includes a first thermal power feedback module and a second thermal power feedback module connected in series, and the transfer function of the first thermal power feedback module is expressed as: The transfer function of the second feedback module of the thermal power plant is expressed as: , Let be the high-pressure turbine coefficient of the m-th thermal power unit. Let be the reheater time constant of the m-th thermal power unit. Let be the mechanical power gain coefficient of the m-th thermal power unit. Let be the speed regulation rate of the generator governor of the m-th thermal power unit; the feedback loop corresponding to the n-th wind turbine unit includes a first wind power feedback module and a second wind power feedback module connected in series, and the transfer function of the first wind power feedback module is expressed as: The transfer function of the second module of the wind power n-feedback is expressed as: , Let be the response time constant of the wind turbine inverter of the nth wind turbine unit. The droop coefficient of the nth wind turbine unit; the sum of the output values ​​of all feedback loops is used as the feedback signal;

[0017] The constructed multi-machine system frequency response (MM-SFR) model is simplified into a convergent response (ASFR) model; in the convergent response (ASFR) model, the step disturbance power... With aggregated feedback signal After subtraction, the frequency deviation is obtained through the aggregation and transfer module. Frequency deviation The aggregated feedback signal is obtained through processing by the aggregated feedback module. The transfer function of the aggregation transfer module is expressed as follows: , Let be the system's equivalent inertial constant. , Let be the normalized inertial constant of the i-th thermal power generating unit. Let i be the installed capacity of the i-th thermal power generating unit. Let be the installed capacity of the j-th wind turbine generator; the transfer function of the aggregation feedback module is expressed as: , The total energy storage coefficient of the system. , Let be the mechanical power gain coefficient of the i-th thermal power unit. Let be the high-pressure turbine coefficient of the i-th thermal power unit. Adjust the speed of the generator governor of the i-th thermal power unit. This represents the total droop coefficient of the system. , The total energy storage time constant of the system. , Let be the reheater time constant of the i-th thermal power unit. Let be the response time constant of the wind turbine inverter of the j-th wind turbine unit;

[0018] Based on the obtained convergent response model ASFR, the frequency deviation is calculated using the inverse Laplace transform. Time-domain expression , is represented as:

[0019]

[0020] In the formula The total damping coefficient of the system; This represents the total droop coefficient of the system. For the system oscillation gain, and , Let be the system damping ratio, and , This is the system's inherent oscillation frequency, and ; This is the actual oscillation frequency of the system, and ; This is the initial phase of the system oscillation, and .

[0021] Step S3 specifically includes the following steps:

[0022] The target hybrid wind farm is designed to use full-power converter wind turbines;

[0023] The active power input of wind turbines in a wind farm is expressed as:

[0024]

[0025] In the formula Let a1 be the active power input of the a1-th wind turbine in the i1-th wind farm; air density; Let a1 be the blade radius of the a1-th wind turbine in the i1-th wind farm; Let a1 be the wind speed at the a1-th wind turbine in the i1-th wind farm; Let a1 be the tip speed ratio of the a1-th wind turbine in the i1-th wind farm, and , Let a1 be the rotor speed of the a1-th wind turbine in the i1-th wind farm; Let a1 be the blade pitch angle of the a1th wind turbine in the i1th wind farm; Let a1 be the wind energy capture coefficient of the a1-th wind turbine in the i1-th wind farm, and , It is the intermediate coefficient, and ;

[0026] The dynamic process of the wind turbine is represented by the following first-order transient model:

[0027]

[0028] In the formula Let a1 be the rotor speed of the a1-th wind turbine in the i1-th wind farm. Rate of change over time; The moment of inertia of the fan; Let a1 be the input torque of the a1-th wind turbine in the i1-th wind farm; Let a1 be the output torque of the a1-th wind turbine in the i1-th wind farm; Let a1 be the input power of the a1-th wind turbine in the i1-th wind farm; Let a1 be the output power of the a1-th wind turbine in the i1-th wind farm.

[0029] Step S4 specifically includes the following steps:

[0030] When system power imbalance causes frequency deviation to exceed the regulation dead zone, the active power output of grid-type wind turbines in the hybrid wind farm is calculated based on the model constructed in steps S2 and S3, and expressed as:

[0031]

[0032] In the formula For the i1th wind farm The active power output of the grid-type wind turbine; For the i1th wind farm The sag coefficient of a platform-type mesh fan; The rated frequency of the power grid; For the real-time frequency of the power grid; For the i1th wind farm Active input power of the grid-type wind turbine.

[0033] Step S5 includes the following steps:

[0034] Based on the operating rules of wind turbines, a model of the kinetic energy stored in the wind turbine rotor is constructed, and the real-time rotor kinetic energy stored in each wind turbine is calculated.

[0035] All grid-connected wind turbines in the target wind farm are aggregated into a frequency regulation support cluster. Based on the real-time rotor kinetic energy stored in each wind turbine, a proportional allocation scheme is used to calculate the sag coefficient of each grid-connected wind turbine and the frequency regulation characteristic parameters required by the grid-connected wind turbine cluster.

[0036] Calculate the frequency regulation power of the grid-connected wind turbine cluster based on the frequency regulation characteristic parameters required for the cluster and the real-time grid frequency.

[0037] Step S5 specifically includes the following steps:

[0038] The following formula is used as a model for the stored kinetic energy of the wind turbine rotor:

[0039]

[0040]

[0041]

[0042]

[0043]

[0044] In the formula The kinetic energy stored for the blade of the a1th wind turbine in the i1th wind farm; Let a1 be the maximum rotor kinetic energy that the a1 wind turbine in the i1th wind farm can absorb when the frequency is disturbed. This represents the maximum rotor speed of the a1-th wind turbine in the i1-th wind farm. Let a1 be the maximum rotor kinetic energy that the a1 wind turbine in the i1th wind farm can release when the frequency is disturbed. Let a1 be the minimum rotor speed of the a1-th wind turbine in the i1-th wind farm; The maximum total rotor kinetic energy that the i1th wind farm can absorb when the frequency is lowered; This represents the total maximum rotor kinetic energy that the i1th wind farm can release when the frequency is disturbed. The total number of wind turbines in the i1th wind farm;

[0045] The sag coefficient of each grid-type wind turbine and the frequency regulation characteristic parameters required for the grid-type wind turbine cluster are calculated using the following formula:

[0046]

[0047]

[0048] In the formula For the i1th wind farm The sag coefficient of a platform-type mesh fan; For the i1th wind farm The maximum rotor kinetic energy that a table-type grid-type wind turbine can absorb under frequency disturbance; The overall frequency regulation coefficient of the i1th wind farm issued by the main grid operator; For the i1th wind farm, there is a set of grid-type wind turbines; For the i1th wind farm The maximum rotor kinetic energy that a table-type grid-type wind turbine can release when subjected to frequency disturbance; For the overall frequency regulation droop characteristic parameter of the grid-connected wind turbine cluster in the i1th wind farm during primary frequency regulation; For the i1th wind farm The maximum rotor kinetic energy that a tandem and grid-type wind turbine can absorb under frequency disturbance; For the i1th wind farm The maximum rotor kinetic energy that a tandem and grid-type wind turbine can release when subjected to frequency disturbance; For the i1th wind farm, there is a set of grid-connected wind turbines; This represents the total number of grid-connected wind turbines in the i1th wind farm;

[0049] Will The data is sent to the local controller of the corresponding grid-type wind turbine to realize the control of the grid-type wind turbine;

[0050] The frequency regulation power of the grid-connected wind turbine cluster is calculated using the following formula:

[0051]

[0052] In the formula Let be the frequency regulation power of the grid-connected wind turbine cluster of the i1th wind farm; For the i1th wind farm The active input power of the tandem and grid-type wind turbines.

[0053] Step S6 includes the following steps:

[0054] Based on the real-time rotor speed and the upper and lower limits of the rotor speed of the grid-type fan, calculate the energy state index of each grid-type fan.

[0055] The output power of each grid-connected fan is calculated with the goal of making the ratio of the unbalanced power of each fan to its corresponding energy state index equal.

[0056] Step S6 specifically includes the following steps:

[0057] The energy state index of each grid-connected wind turbine is calculated using the following formula:

[0058]

[0059] In the formula For the i1th wind farm Energy State Index of terrazzo and grid-type wind turbines; For the i1th wind farm The upper limit of rotor speed for both slab and mesh type fans; For the i1th wind farm The lower limit of rotor speed for tandem and mesh type fans;

[0060] The ratio of the unbalanced power of each grid-type wind turbine to its corresponding energy state index is set to be equal, expressed as:

[0061]

[0062] In the formula For the i1th wind farm Output power of pedestal and grid-type fans; For the i1th wind farm Output power of pedestal and grid-type fans; For the i1th wind farm The active power input of the tandem and grid-type wind turbines; For the i1th wind farm Energy State Index of terrazzo and grid-type wind turbines;

[0063] Based on the energy state index of each grid-connected wind turbine, and with the objective of ensuring that the ratio of the unbalanced power to the corresponding energy state index of each grid-connected wind turbine is equal, the output power of each grid-connected wind turbine is calculated:

[0064]

[0065] The output power of each grid-connected wind turbine is obtained and sent to the local controller of the corresponding grid-connected wind turbine to realize the control of the grid-connected wind turbine.

[0066] This invention also provides a system for implementing the primary frequency regulation control method of the hybrid wind farm, comprising a data acquisition module, a model simplification module, a model construction module, an active power calculation module, a frequency regulation calculation module, an output calculation module, and a primary frequency regulation module; the data acquisition module, model simplification module, model construction module, active power calculation module, frequency regulation calculation module, output calculation module, and primary frequency regulation module are connected in series; the data acquisition module is used to acquire data information of the target power system and the corresponding hybrid wind farm, and upload the data information to the model simplification module; the model simplification module is used to construct a multi-machine system frequency response model of the target power system based on the received data information and the acquired data information, and simplify it to obtain a converged response model, and upload the data information to the model construction module; the model construction module is used to construct the primary frequency regulation of the hybrid wind farm based on the received data information and the acquired data information, and based on the wind turbine output power and the dynamic process of the wind turbine. The system employs a dynamic model and uploads the data to the active power calculation module. The active power calculation module, based on the received data, calculates the active power output of grid-type wind turbines in the hybrid wind farm when system power imbalance causes frequency deviation to exceed the regulation dead zone, and uploads the data to the frequency regulation calculation module. The frequency regulation calculation module, based on the received data and the real-time rotor kinetic energy stored in each turbine in the hybrid wind farm, calculates the droop coefficient of each grid-type wind turbine and the required frequency regulation power of the grid-connected turbine cluster, and uploads the data to the output calculation module. The output calculation module, based on the received data and the frequency regulation characteristic parameters of the grid-connected turbine cluster, real-time system frequency, and energy state index, calculates the output power of each grid-connected wind turbine and uploads the data to the primary frequency regulation module. The primary frequency regulation module, based on the received data, completes the primary frequency regulation control of the hybrid wind farm.

[0067] The primary frequency regulation control method and system for hybrid wind farms provided by this invention, through modeling and constructing the target power system and the target hybrid wind farm, as well as the corresponding power calculation and parameter calculation, not only realizes the primary frequency regulation control of the hybrid wind farm, but also has higher reliability and better accuracy. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0069] Figure 2 This is a schematic diagram of the structure of the MM-SFR model of the frequency response of a multi-machine system according to the method of the present invention.

[0070] Figure 3 This is a schematic diagram of the structure of the aggregation response model ASFR of the method of the present invention.

[0071] Figure 4 This is a schematic diagram of the simulation results of the wind turbine speed control accuracy at frequencies below the rated frequency in an embodiment of the method of the present invention.

[0072] Figure 5 This is a schematic diagram of the simulation results of the power control accuracy of wind turbine units at frequencies below the rated frequency in an embodiment of the method of the present invention.

[0073] Figure 6 This is a schematic diagram illustrating the simulation results of the frequency regulation process of a centralized wind farm 3 under different control strategies, as an embodiment of the method of the present invention; wherein... Figure 6 (a) is a schematic diagram of the fan speed curve. Figure 6 (b) is a schematic diagram of the wind turbine power curve. Figure 6 (c) is a schematic diagram of the wind farm power curve. Figure 6 (d) is a schematic diagram of the system frequency curve.

[0074] Figure 7 This is a schematic diagram of the functional modules of the system of the present invention. Detailed Implementation

[0075] like Figure 1 The diagram shown is a flowchart of the method of the present invention: The primary frequency regulation control method for this hybrid wind farm disclosed in the present invention includes the following steps:

[0076] S1. Obtain data information on the target power system and the corresponding hybrid wind farm;

[0077] S2. Based on the data obtained in step S1, construct a multi-machine system frequency response model of the target power system and simplify it to obtain a converged response model; specifically, this includes the following steps:

[0078] Based on the data obtained in step S1, construct a multi-machine system frequency response (MM-SFR) model of the target power system (e.g., Figure 2 As shown); in the constructed model, the step disturbance power The frequency deviation is obtained by subtracting the feedback signal from the first transmission module. The transfer function of the first transfer module is expressed as follows: , The normalized inertial constant of the thermal power generating unit. The normalized damping constant of the thermal power generating unit; frequency deviation Feedback signals are obtained through feedback loops; each of the m thermal power units and n wind power units in the target power system is modeled as a feedback loop; the feedback loop corresponding to the m-th thermal power unit includes a first thermal power feedback module and a second thermal power feedback module connected in series, and the transfer function of the first thermal power feedback module is expressed as: The transfer function of the second feedback module of the thermal power plant is expressed as: , Let be the high-pressure turbine coefficient of the m-th thermal power unit. Let be the reheater time constant of the m-th thermal power unit. Let be the mechanical power gain coefficient of the m-th thermal power unit. Let be the speed regulation rate of the generator governor of the m-th thermal power unit; the feedback loop corresponding to the n-th wind turbine unit includes a first wind power feedback module and a second wind power feedback module connected in series, and the transfer function of the first wind power feedback module is expressed as: The transfer function of the second module of the wind power n-feedback is expressed as: , Let be the response time constant of the wind turbine inverter of the nth wind turbine unit. The droop coefficient of the nth wind turbine unit; the sum of the output values ​​of all feedback loops is used as the feedback signal;

[0079] Because the MM-SFR model has a complex structure and it is difficult to directly obtain the analytical expression for the frequency, this invention simplifies the constructed multi-machine system frequency response MM-SFR model into an aggregated response model ASFR (e.g., Figure 3 As shown); in the aggregate response model ASFR, the step disturbance power With aggregated feedback signal After subtraction, the frequency deviation is obtained through the aggregation and transfer module. Frequency deviation The aggregated feedback signal is obtained through processing by the aggregated feedback module. The transfer function of the aggregation transfer module is expressed as follows: , Let be the system's equivalent inertial constant. , Let be the normalized inertial constant of the i-th thermal power generating unit. Let i be the installed capacity of the i-th thermal power generating unit. Let be the installed capacity of the j-th wind turbine generator; the transfer function of the aggregation feedback module is expressed as: , The total energy storage coefficient of the system. , Let be the mechanical power gain coefficient of the i-th thermal power unit. Let be the high-pressure turbine coefficient of the i-th thermal power unit. Adjust the speed of the generator governor of the i-th thermal power unit. The total droop coefficient of the system. , The total energy storage time constant of the system. , Let be the reheater time constant of the i-th thermal power unit. Let be the response time constant of the wind turbine inverter of the j-th wind turbine unit;

[0080] Based on the obtained convergent response model ASFR, the frequency deviation is calculated using the inverse Laplace transform. Time-domain expression , is represented as:

[0081]

[0082] In the formula The total damping coefficient of the system; This represents the total droop coefficient of the system. For the system oscillation gain, and , Let be the system damping ratio, and , This is the system's inherent oscillation frequency, and ; This is the actual oscillation frequency of the system, and ; This is the initial phase of the system oscillation, and .

[0083] S3. Based on the data obtained in step S1, and considering the turbine output power and dynamic process of the wind turbine, construct a primary frequency regulation dynamic model for the hybrid wind farm; specifically including the following steps:

[0084] The target hybrid wind farm is designed to use full-power converter wind turbines;

[0085] The active power input of wind turbines in a wind farm is expressed as:

[0086]

[0087] In the formula Let a1 be the active power input of the a1-th wind turbine in the i1-th wind farm; air density; Let a1 be the blade radius of the a1-th wind turbine in the i1-th wind farm; Let a1 be the wind speed at the a1-th wind turbine in the i1-th wind farm; Let a1 be the tip speed ratio of the a1-th wind turbine in the i1-th wind farm, and , Let a1 be the rotor speed of the a1-th wind turbine in the i1-th wind farm; Let a1 be the blade pitch angle of the a1th wind turbine in the i1th wind farm; Let a1 be the wind energy capture coefficient of the a1-th wind turbine in the i1-th wind farm, and , It is the intermediate coefficient, and ;

[0088] When a wind turbine uses rotor kinetic energy for frequency regulation, a mismatch occurs between the turbine power and the output electromagnetic power, causing dynamic changes in the rotor speed. Therefore, the dynamic process of the wind turbine is represented by the following first-order transient model:

[0089]

[0090] In the formula Let a1 be the rotor speed of the a1-th wind turbine in the i1-th wind farm. Rate of change over time; The moment of inertia of the fan; Let a1 be the input torque of the a1-th wind turbine in the i1-th wind farm; Let a1 be the output torque of the a1-th wind turbine in the i1-th wind farm; Let a1 be the input power of the a1-th wind turbine in the i1-th wind farm; Let a1 be the output power of the a1-th wind turbine in the i1-th wind farm;

[0091] S4. When system power imbalance causes frequency deviation to exceed the regulation dead zone, calculate the active power output of grid-type wind turbines in the hybrid wind farm based on the model constructed in steps S2 and S3; specifically including the following steps:

[0092] In this invention, a centralized controller allocates frequency regulation coefficients to grid-type wind turbines and issues frequency regulation power commands to grid-type wind turbines.

[0093] When system power imbalance causes frequency deviation to exceed the regulation dead zone, the active power output of grid-type wind turbines in the hybrid wind farm is calculated based on the model constructed in steps S2 and S3, and expressed as:

[0094]

[0095] In the formula For the i1th wind farm The active power output of the grid-type wind turbine; For the i1th wind farm The sag coefficient of a platform-type mesh fan; The rated frequency of the power grid; For the real-time frequency of the power grid; For the i1th wind farm Active input power of the grid-type wind turbine;

[0096] Unlike grid-type fans, follow-grid fans participate in frequency regulation services through frequency regulation power issued by a centralized controller; therefore, the key to achieving fast and accurate overall frequency regulation is to reasonably allocate the frequency regulation coefficient of grid-type fans and the frequency regulation power of follow-grid fans.

[0097] S5. Based on the data obtained in step S4, and considering the real-time rotor kinetic energy stored in each wind turbine in the hybrid wind farm, calculate the sag coefficient of each grid-type wind turbine and the frequency regulation power required by the grid-type wind turbine cluster; including the following steps:

[0098] The present invention aims to rationally allocate frequency regulation commands based on the kinetic energy stored in each wind turbine within the wind farm;

[0099] Based on the operating rules of wind turbines, a model of the kinetic energy stored in the wind turbine rotor is constructed, and the real-time rotor kinetic energy stored in each wind turbine is calculated.

[0100] All grid-connected wind turbines in the target wind farm are aggregated into a frequency regulation support cluster. Based on the real-time rotor kinetic energy stored in each wind turbine, a proportional allocation scheme is used to calculate the sag coefficient of each grid-connected wind turbine and the frequency regulation characteristic parameters required by the grid-connected wind turbine cluster.

[0101] Calculate the frequency regulation power of the grid-connected wind turbine cluster based on the frequency regulation characteristic parameters required by the grid-connected wind turbine cluster and the real-time frequency of the power grid.

[0102] The specific implementation includes the following steps:

[0103] The following formula is used as a model for the stored kinetic energy of the wind turbine rotor:

[0104]

[0105]

[0106]

[0107]

[0108]

[0109] In the formula The kinetic energy stored for the blade of the a1th wind turbine in the i1th wind farm; Let a1 be the maximum rotor kinetic energy that the a1 wind turbine in the i1th wind farm can absorb when the frequency is disturbed. This represents the maximum rotor speed of the a1-th wind turbine in the i1-th wind farm. Let a1 be the maximum rotor kinetic energy that the a1 wind turbine in the i1th wind farm can release when the frequency is disturbed. Let a1 be the minimum rotor speed of the a1-th wind turbine in the i1-th wind farm; The maximum total rotor kinetic energy that the i1th wind farm can absorb when the frequency is lowered; This represents the total maximum rotor kinetic energy that the i1th wind farm can release when the frequency is disturbed. The total number of wind turbines in the i1th wind farm;

[0110] The sag coefficient of each grid-type wind turbine and the frequency regulation characteristic parameters required for the grid-type wind turbine cluster are calculated using the following formula:

[0111]

[0112]

[0113] In the formula For the i1th wind farm The sag coefficient of a platform-type mesh fan; For the i1th wind farm The maximum rotor kinetic energy that a table-type grid-type wind turbine can absorb under frequency disturbance; The overall frequency regulation coefficient of the i1th wind farm issued by the main grid operator; For the i1th wind farm, there is a set of grid-type wind turbines; For the i1th wind farm The maximum rotor kinetic energy that a table-type grid-type wind turbine can release when subjected to frequency disturbance; For the overall frequency regulation droop characteristic parameter of the grid-connected wind turbine cluster in the i1th wind farm during primary frequency regulation; For the i1th wind farm The maximum rotor kinetic energy that a tandem and grid-type wind turbine can absorb under frequency disturbance; For the i1th wind farm The maximum rotor kinetic energy that a tandem and grid-type wind turbine can release when subjected to frequency disturbance; For the i1th wind farm, there is a set of grid-connected wind turbines; This represents the total number of grid-connected wind turbines in the i1th wind farm;

[0114] Will The data is sent to the local controller of the corresponding grid-type wind turbine to realize the control of the grid-type wind turbine;

[0115] The frequency regulation power of the grid-connected wind turbine cluster is calculated using the following formula:

[0116]

[0117] In the formula Let be the frequency regulation power of the grid-connected wind turbine cluster of the i1th wind farm; For the i1th wind farm The active power input of the tandem and grid-type wind turbines;

[0118] S6. Based on the frequency regulation characteristic parameters of the grid-connected wind turbine cluster, the real-time system frequency, and the energy state index, calculate the output power of each grid-connected wind turbine; including the following steps:

[0119] Based on the real-time rotor speed and the upper and lower limits of the rotor speed of the grid-type fan, calculate the energy state index of each grid-type fan.

[0120] With the goal of making the ratio of the unbalanced power of each grid-connected fan to the corresponding energy state index equal, the output power of each grid-connected fan is calculated.

[0121] The specific implementation includes the following steps:

[0122] After obtaining the frequency regulation power of the grid-connected wind turbine cluster, it is necessary to rationally allocate the active power among the grid-connected wind turbines, taking into account the rotor speed constraints, in order to avoid operational safety issues caused by excessively high or low rotor speeds. Since the wind turbine models in the wind farm may differ, it is difficult to uniformly characterize the usable rotor kinetic energy of the wind turbines based solely on rotor speed. Therefore, this invention introduces a State of Energy (SOE) index to achieve a rational power allocation among the grid-connected wind turbines, ensuring system safety while fully utilizing the frequency regulation capability of each wind turbine.

[0123] The energy state index of each grid-connected wind turbine is calculated using the following formula:

[0124]

[0125] In the formula For the i1th wind farm Energy State Index of terrazzo and grid-type wind turbines; For the i1th wind farm The upper limit of rotor speed for both slab and mesh type fans; For the i1th wind farm The lower limit of rotor speed for tandem and mesh type fans;

[0126] SOE is a dimensionless ratio indicator. When its value is close to 0 or 1, it indicates that the wind turbine has almost exhausted its available mechanical energy due to participating in the frequency regulation process. Therefore, the optimal power distribution scheme of this invention should ensure that the ratio of the unbalanced power of each grid-connected wind turbine to its SOE remains consistent, expressed as:

[0127]

[0128] In the formula For the i1th wind farm Output power of pedestal and grid-type fans; For the i1th wind farm Output power of pedestal and grid-type fans; For the i1th wind farm The active power input of the tandem and grid-type wind turbines; For the i1th wind farm Energy State Index of terrazzo and grid-type wind turbines;

[0129] Based on the energy state index of each grid-connected wind turbine, and with the objective of ensuring that the ratio of the unbalanced power to the corresponding energy state index of each grid-connected wind turbine is equal, the output power of each grid-connected wind turbine is calculated:

[0130]

[0131] The output power of each grid-connected wind turbine is obtained and sent to the local controller of the corresponding grid-connected wind turbine to realize the control of the grid-connected wind turbine;

[0132] In this way, the frequency regulation power of each grid-type wind turbine can be reasonably allocated, so that at the end of a frequency response process, the rotor speed of all wind turbines can reach their limit value at the same time, thereby maximizing the utilization of the rotor kinetic energy stored in each wind turbine.

[0133] S7. Complete the primary frequency regulation control of the hybrid wind farm.

[0134] The method of the present invention will be further described below with reference to an embodiment:

[0135] Taking the IEEE-39 node test system as the research object,

[0136] The test system includes 10 synchronous generators with a capacity of 150 MW each, and 3 centralized wind farms with installed capacities of 72 MW, 96 MW, and 120 MW, respectively, consisting of 12, 16, and 20 wind turbines. Each wind turbine has a capacity of 6 MW, and the anemometers in each centralized site correspond to 4 wind turbines.

[0137] Assuming a severe system power imbalance occurs at the start of a frequency regulation process, with power system load fluctuations of ±300MW, simulate frequency rise and fall scenarios. The rotational speed range of the renewable energy units is [0.7, 1.3] pu, and the active power regulation range of the renewable energy units is [1.2, 6.6] MW. Sixteen wind speed scenarios ranging from 8 to 12 m / s were simulated in the test.

[0138] Control parameters were obtained using the method of this invention, time-domain simulations were performed, and the final rotor speed and initial regulated power of the wind turbine generator after a single frequency adjustment were observed in the test scenario. The mean relative error (MRE) and root mean square error (RMSE) were used to analyze the deviation of the wind turbine generator rotor speed and power from their boundary values. For clarity, MRE1 / RMSE1 represents the maximum relative error / RMSE of centralized power station 1. In comparison, this invention also conducted simulations using a non-iterative state-space transformation method (blue), a time-domain simulation based on an inaccurate physical model (i.e., load fluctuation deviation of -8% and wind energy utilization coefficient deviation of +6%) (red), and an artificial neural network (ANN) method (purple). The simulation results are as follows: Figure 4 and Figure 5 As shown.

[0139] The results show that the deviation of the proposed method is closer to the boundary value than the other methods mentioned above. Comparative results verify that the control performance of the proposed method is parameter-independent, and that it fully considers dynamic frequency changes through cooperative iteration, thus fully exploiting the frequency regulation capability of the wind turbine.

[0140] In contrast, this invention also presents actual frequency modulation dynamic results based on an inaccurate physical model, a non-iterative state-space transformation method, and an artificial neural network (ANN) method. Taking a centralized wind farm 3 as an example, the results are as follows: Figure 6 As shown.

[0141] When using the method of this invention, the power output of wind farm 3 is effectively improved throughout the frequency regulation process, and the final rotor speed of the wind turbine is closer to the boundary value. Conversely, when using the coefficients obtained by the state-space transformation method without iteration, the inaccurate physical model, or the ANN method, the rotor speed and power output may exceed or fail to reach the corresponding limit values ​​during a single frequency regulation process.

[0142] The results verify that the method of the present invention can effectively prevent rotor speed and power output from exceeding the safety boundary, fully exploit the frequency regulation capability of centralized wind farms, and ensure the safety of centralized wind farms.

[0143] This invention, by establishing a frequency model of the power system and an electromechanical transient model of the wind turbine in a high-penetration wind power environment, accurately reflects the dynamic response characteristics of the wind turbine during primary frequency regulation, providing a reliable theoretical basis for the design of control strategies. This invention proposes using the wind turbine rotor energy state index as a frequency regulation energy evaluation index, which can reflect the actual frequency regulation potential of the wind turbine under different operating conditions in real time, overcoming the limitation of inaccurate frequency regulation capability assessment in traditional methods. This invention, through a centralized controller, achieves coordinated and optimized allocation of the droop coefficient of grid-connected wind turbines and the power command of grid-following wind turbines, improving the overall frequency regulation capability of the wind farm while ensuring rapid system response and safe operation.

[0144] like Figure 7 The diagram shows the functional modules of the system of the present invention: The system for implementing the primary frequency regulation control method of the hybrid wind farm disclosed in this invention includes a data acquisition module, a model simplification module, a model construction module, an active power calculation module, a frequency regulation calculation module, an output calculation module, and a primary frequency regulation module; the data acquisition module, model simplification module, model construction module, active power calculation module, frequency regulation calculation module, output calculation module, and primary frequency regulation module are connected in series; the data acquisition module is used to acquire data information of the target power system and the corresponding hybrid wind farm, and upload the data information to the model simplification module; the model simplification module is used to construct a multi-machine system frequency response model of the target power system based on the received data information and the acquired data information, and simplify it to obtain a converged response model, and upload the data information to the model construction module; the model construction module is used to construct a hybrid wind farm based on the received data information and the acquired data information, and based on the wind turbine output power and the dynamic process of the wind turbine, a model of the hybrid wind farm is constructed. The system first establishes a dynamic model for primary frequency regulation of the wind farm and uploads the data to the active power calculation module. The active power calculation module, based on the received data, calculates the active power output of grid-connected wind turbines in the hybrid wind farm when system power imbalance causes frequency deviation to exceed the regulation dead zone, and uploads this data to the frequency regulation calculation module. The frequency regulation calculation module, based on the received data and the real-time rotor kinetic energy stored in each turbine in the hybrid wind farm, calculates the droop coefficient of each grid-connected wind turbine and the required frequency regulation power of the grid-connected turbine cluster, and uploads this data to the output calculation module. The output calculation module, based on the received data and the frequency regulation characteristic parameters of the grid-connected turbine cluster, real-time system frequency, and energy state index, calculates the output power of each grid-connected wind turbine and uploads this data to the primary frequency regulation module. The primary frequency regulation module then completes the primary frequency regulation control of the hybrid wind farm based on the received data.

Claims

1. A primary frequency regulation control method for a hybrid wind farm, characterized in that... Includes the following steps: S1. Obtain data information on the target power system and the corresponding hybrid wind farm; S2. Based on the data obtained in step S1, construct a multi-machine system frequency response model of the target power system and simplify it to obtain a converged response model; S3. Based on the data obtained in step S1, construct a primary frequency regulation dynamic model of the hybrid wind farm based on the wind turbine output power and the dynamic process of the wind turbine; S4. When the frequency deviation exceeds the adjustment dead zone due to system power imbalance, calculate the active power output of the grid-type wind turbines in the hybrid wind farm based on the model constructed in steps S2 and S3. S5. Based on the data obtained in step S4, and considering the real-time rotor kinetic energy stored in each wind turbine in the hybrid wind farm, calculate the sag coefficient of each grid-type wind turbine and the frequency regulation power required by the grid-type wind turbine cluster; including the following steps: Based on the operating rules of wind turbines, a model of the kinetic energy stored in the wind turbine rotor is constructed, and the real-time rotor kinetic energy stored in each wind turbine is calculated. All grid-connected wind turbines in the target wind farm are aggregated into a frequency regulation support cluster. Based on the real-time rotor kinetic energy stored in each wind turbine, a proportional allocation scheme is used to calculate the sag coefficient of each grid-connected wind turbine and the frequency regulation characteristic parameters required by the grid-connected wind turbine cluster. Calculate the frequency regulation power of the grid-connected wind turbine cluster based on the frequency regulation characteristic parameters required by the grid-connected wind turbine cluster and the real-time frequency of the power grid. S6. Based on the frequency regulation characteristic parameters of the grid-connected wind turbine cluster, the real-time system frequency, and the energy state index, calculate the output power of each grid-connected wind turbine; including the following steps: Based on the real-time rotor speed and the upper and lower limits of the rotor speed of the grid-type fan, calculate the energy state index of each grid-type fan. With the goal of making the ratio of the unbalanced power of each grid-connected fan to the corresponding energy state index equal, the output power of each grid-connected fan is calculated. S7. Complete the primary frequency regulation control of the hybrid wind farm.

2. The primary frequency regulation control method for a hybrid wind farm according to claim 1, characterized in that... Step S2 specifically includes the following steps: Based on the data obtained in step S1, a multi-machine system frequency response model of the target power system is constructed; in the constructed model, the step disturbance power... The frequency deviation is obtained by subtracting the feedback signal from the first transmission module. The transfer function of the first transfer module is expressed as follows: , The normalized inertial constant of the thermal power generating unit. The normalized damping constant of the thermal power generating unit; frequency deviation Feedback signals are obtained through feedback loops; each of the m thermal power units and n wind power units in the target power system is modeled as a feedback loop; the feedback loop corresponding to the m-th thermal power unit includes a first thermal power feedback module and a second thermal power feedback module connected in series, and the transfer function of the first thermal power feedback module is expressed as: The transfer function of the second feedback module of the thermal power plant is expressed as: , Let be the high-pressure turbine coefficient of the m-th thermal power unit. Let be the reheater time constant of the m-th thermal power unit. Let be the mechanical power gain coefficient of the m-th thermal power unit. Let be the speed regulation rate of the generator governor of the m-th thermal power unit; the feedback loop corresponding to the n-th wind turbine unit includes a first wind power feedback module and a second wind power feedback module connected in series, and the transfer function of the first wind power feedback module is expressed as: The transfer function of the second module of the wind power n-feedback is expressed as: , Let be the response time constant of the wind turbine inverter of the nth wind turbine unit. The droop coefficient of the nth wind turbine unit; the sum of the output values ​​of all feedback loops is used as the feedback signal; The constructed multi-machine system frequency response model is simplified into a convergent response model; in the convergent response model, the step disturbance power... With aggregated feedback signal After subtraction, the frequency deviation is obtained through the aggregation and transfer module. Frequency deviation The aggregated feedback signal is obtained through processing by the aggregated feedback module. The transfer function of the aggregation transfer module is expressed as follows: , Let be the system's equivalent inertial constant. , Let be the normalized inertial constant of the i-th thermal power generating unit. Let i be the installed capacity of the i-th thermal power generating unit. Let be the installed capacity of the j-th wind turbine generator; the transfer function of the aggregation feedback module is expressed as: , The total energy storage coefficient of the system. , Let be the mechanical power gain coefficient of the i-th thermal power unit. Let be the high-pressure turbine coefficient of the i-th thermal power unit. Adjust the speed of the generator governor of the i-th thermal power unit. This represents the total droop coefficient of the system. , The total energy storage time constant of the system. , Let be the reheater time constant of the i-th thermal power unit. Let be the response time constant of the wind turbine inverter of the j-th wind turbine unit; Based on the obtained aggregate response model, the frequency deviation is calculated using the inverse Laplace transform. Time-domain expression , represented as: In the formula The total damping coefficient of the system; This represents the total droop coefficient of the system. For the system oscillation gain, and , Let be the system damping ratio, and , This is the system's inherent oscillation frequency, and ; This is the actual oscillation frequency of the system, and ; This is the initial phase of the system oscillation, and .

3. The primary frequency regulation control method for a hybrid wind farm according to claim 2, characterized in that... Step S3 specifically includes the following steps: The target hybrid wind farm is designed to use full-power converter wind turbines; The input power of the wind turbines in a wind farm is expressed as: In the formula Let a1 be the input power of the a1-th wind turbine in the i1-th wind farm; air density; Let a1 be the blade radius of the a1-th wind turbine in the i1-th wind farm; Let a1 be the wind speed at the a1-th wind turbine in the i1-th wind farm; Let a1 be the tip speed ratio of the a1-th wind turbine in the i1-th wind farm, and , Let a1 be the rotor speed of the a1-th wind turbine in the i1-th wind farm; Let a1 be the blade pitch angle of the a1th wind turbine in the i1th wind farm; Let a1 be the wind energy capture coefficient of the a1-th wind turbine in the i1-th wind farm, and , It is the intermediate coefficient, and ; The dynamic process of the wind turbine is represented by the following first-order transient model: In the formula Let a1 be the rotor speed of the a1-th wind turbine in the i1-th wind farm. Rate of change over time; The moment of inertia of the fan; Let a1 be the input torque of the a1-th wind turbine in the i1-th wind farm; Let a1 be the output torque of the a1-th wind turbine in the i1-th wind farm; Let a1 be the input power of the a1-th wind turbine in the i1-th wind farm; Let a1 be the output power of the a1-th wind turbine in the i1-th wind farm.

4. The primary frequency regulation control method for a hybrid wind farm according to claim 3, characterized in that... Step S4 specifically includes the following steps: When system power imbalance causes frequency deviation to exceed the regulation dead zone, the active power output of grid-type wind turbines in the hybrid wind farm is calculated based on the model constructed in steps S2 and S3, and expressed as: In the formula For the i1th wind farm The active power output of the grid-type wind turbine; For the i1th wind farm The sag coefficient of a platform-type mesh fan; The rated frequency of the power grid; For the real-time frequency of the power grid; For the i1th wind farm Active input power of the grid-type wind turbine.

5. The primary frequency regulation control method for a hybrid wind farm according to claim 4, characterized in that... Step S5 specifically includes the following steps: The following formula is used as a model for the stored kinetic energy of the wind turbine rotor: In the formula The kinetic energy stored for the blade of the a1th wind turbine in the i1th wind farm; Let a1 be the maximum rotor kinetic energy that the a1 wind turbine in the i1th wind farm can absorb when the frequency is disturbed. This represents the maximum rotor speed of the a1-th wind turbine in the i1-th wind farm. Let a1 be the maximum rotor kinetic energy that the a1 wind turbine in the i1th wind farm can release when the frequency is disturbed. Let a1 be the minimum rotor speed of the a1-th wind turbine in the i1-th wind farm; The maximum total rotor kinetic energy that the i1th wind farm can absorb when the frequency is lowered; This represents the total maximum rotor kinetic energy that the i1th wind farm can release when the frequency is disturbed. The total number of wind turbines in the i1th wind farm; The sag coefficient of each grid-type wind turbine and the frequency regulation characteristic parameters required for the grid-type wind turbine cluster are calculated using the following formula: In the formula For the i1th wind farm The sag coefficient of a platform-type mesh fan; For the i1th wind farm The maximum rotor kinetic energy that a table-type grid-type wind turbine can absorb under frequency disturbance; The overall frequency regulation coefficient of the i1th wind farm issued by the main grid operator; For the i1th wind farm, there is a set of grid-type wind turbines; For the i1th wind farm The maximum rotor kinetic energy that a table-type grid-type wind turbine can release when subjected to frequency disturbance; For the overall frequency regulation droop characteristic parameter of the grid-connected wind turbine cluster in the i1th wind farm during primary frequency regulation; For the i1th wind farm The maximum rotor kinetic energy that a tandem and grid-type wind turbine can absorb under frequency disturbance; For the i1th wind farm The maximum rotor kinetic energy that a tandem and grid-type wind turbine can release when subjected to frequency disturbance; For the i1th wind farm, there is a set of grid-connected wind turbines; This represents the total number of grid-connected wind turbines in the i1th wind farm; Will The data is sent to the local controller of the corresponding grid-type wind turbine to realize the control of the grid-type wind turbine; The frequency regulation power of the grid-connected wind turbine cluster is calculated using the following formula: In the formula Let be the frequency regulation power of the grid-connected wind turbine cluster of the i1th wind farm; For the i1th wind farm The active input power of the tandem and grid-type wind turbines.

6. The primary frequency regulation control method for a hybrid wind farm according to claim 5, characterized in that... Step S6 specifically includes the following steps: The energy state index of each grid-connected wind turbine is calculated using the following formula: In the formula For the i1th wind farm Energy State Index of terrazzo and grid-type wind turbines; For the i1th wind farm The upper limit of rotor speed for both slab and mesh type fans; For the i1th wind farm Lower limit of rotor speed for tandem and grid-type fans; The ratio of the unbalanced power of each grid-type wind turbine to its corresponding energy state index is set to be equal, expressed as: In the formula For the i1th wind farm Output power of pedestal and grid-type fans; For the i1th wind farm Output power of pedestal and grid-type fans; For the i1th wind farm The active power input of the tandem and grid-type wind turbines; For the i1th wind farm Energy State Index of terrazzo and grid-type wind turbines; Based on the energy state index of each grid-connected wind turbine, and with the objective of ensuring that the ratio of the unbalanced power to the corresponding energy state index of each grid-connected wind turbine is equal, the output power of each grid-connected wind turbine is calculated: The output power of each grid-connected wind turbine is obtained and sent to the local controller of the corresponding grid-connected wind turbine to realize the control of the grid-connected wind turbine.

7. A system for implementing the primary frequency regulation control method for a hybrid wind farm as described in any one of claims 1 to 6, characterized in that... It includes a data acquisition module, a model simplification module, a model building module, an active power calculation module, a frequency regulation calculation module, an output calculation module, and a primary frequency regulation module; the data acquisition module, model simplification module, model building module, active power calculation module, frequency regulation calculation module, output calculation module, and primary frequency regulation module are connected in series; the data acquisition module is used to acquire data information of the target power system and the corresponding hybrid wind farm, and upload the data information to the model simplification module; The model simplification module is used to construct a multi-machine system frequency response model of the target power system based on the received data information and the acquired data information, and to simplify it to obtain a aggregate response model, and then upload the data information to the model construction module; The model building module is used to construct a primary frequency regulation dynamic model of the hybrid wind farm based on the received data and the acquired data, and based on the wind turbine output power and the dynamic process of the wind turbine, and upload the data to the active power calculation module; the active power calculation module is used to calculate the active power output of the grid-type wind turbines in the hybrid wind farm based on the constructed model, when the frequency deviation exceeds the regulation dead zone due to system power imbalance, and upload the data to the frequency regulation calculation module. The frequency regulation calculation module is used to calculate the sag coefficient of each grid-type wind turbine and the frequency regulation power required by the grid-type wind turbine cluster based on the received data information and the real-time rotor kinetic energy stored in each wind turbine in the hybrid wind farm, and upload the data information to the output calculation module. The output calculation module is used to calculate the output power of each grid-connected wind turbine based on the received data, the frequency regulation characteristic parameters of the grid-connected wind turbine cluster, the real-time system frequency, and the energy state index, and upload the data to the primary frequency regulation module; the primary frequency regulation module is used to complete the primary frequency regulation control of the hybrid wind farm based on the received data.

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