Wind-storage combined power plants participating in frequency regulation optimization control methods, systems, equipment, and media

Abstract

This invention provides a method, system, equipment, and medium for frequency regulation optimization control of a wind-storage combined power station. During primary frequency regulation, the system releases rotor kinetic energy through virtual inertial control of the wind turbine to dampen frequency drops during the inertial response phase. Energy storage compensates for the later-stage power output decline of the wind turbine and avoids secondary frequency drops caused by the wind turbine, effectively improving the frequency response characteristics of the system during primary frequency regulation. During secondary frequency regulation, aiming to minimize the cost of automatic power generation control involving the frequency-regulating power source, reference values ​​for wind turbine power variation and energy storage power variation are determined. Secondary frequency regulation control is then performed based on these reference values, taking into account not only the state of charge of the energy storage power station itself but also coordinating with the wind turbine's operating conditions in real time. This extends the lifespan of the energy storage while improving the dynamic frequency characteristics of the system.

Description

Technical Field

[0001] This invention relates to the field of power system operation control, specifically to a method, system, equipment, and medium for frequency regulation optimization control of a wind-storage combined power plant. Background Technology

[0002] In recent years, new energy sources, represented by wind power, have developed rapidly. However, due to the low rotor inertia of wind turbines and their current primary operation in maximum power point tracking (MPPT) mode, they generally lack the active grid support capabilities similar to conventional synchronous turbines in terms of inertia support and primary frequency regulation. Furthermore, with the increasing penetration rate of wind power, existing control methods are insufficient to meet the requirements of grid frequency stability. Therefore, current research has proposed technologies such as virtual inertial control, overspeed load shedding control, and pitch control to enhance the ability of wind turbines to participate in grid frequency regulation. Simultaneously, energy storage technologies, represented by electrochemical and flywheel technologies, possess advantages such as fast response speed and strong controllability. Combining wind power with wind power to form wind-storage integrated power plants can effectively address the problems of large output fluctuations and insufficient grid regulation capabilities of wind power and other new energy sources. Therefore, the participation of wind-storage integrated power plants in frequency regulation is an important technical means to solve the insufficient frequency response characteristics of the grid under high wind power penetration.

[0003] In practical engineering applications, the capacity of a single wind turbine is relatively small, and a wind farm typically consists of hundreds of turbines operating under different conditions. When wind farms participate in grid frequency regulation, it is necessary to fully consider factors such as the spatiotemporal distribution characteristics of wind speed within the wind farm, the actual operating status of each wind turbine, and the frequency response characteristics of different frequency regulation control technologies for wind turbines at different wind speeds. Furthermore, it is also necessary to coordinate control strategies with the operating status of energy storage devices. Therefore, researching an optimized control method for wind-storage combined power plants participating in frequency regulation is of great significance. Summary of the Invention

[0004] To address the issue of reduced grid frequency stability under high wind power penetration, this invention proposes a method for frequency regulation optimization control involving a combined wind and energy storage power plant, comprising:

[0005] When secondary frequency regulation is required, the reference values ​​for wind turbine power change and energy storage power change are determined with the goal of minimizing the cost of the frequency regulation power supply participating in automatic power generation control.

[0006] Secondary frequency regulation control is performed based on the reference values ​​for the change in wind turbine power and the change in energy storage power.

[0007] Preferably, the objective of minimizing the cost of frequency-modulated power supply participation in automatic power generation control includes:

[0008] An objective function is constructed with the goal of minimizing the cost of frequency modulation power supply participating in automatic generation control, and constraints are determined for the objective function.

[0009] Among them, the minimum cost of the frequency-regulated power supply participating in automatic power generation control includes: the minimum secondary frequency regulation cost of each wind turbine and the minimum frequency regulation cost of each energy storage unit at the current moment; the secondary frequency regulation cost of the wind turbine is described by a quadratic function of the turbine offset power; the secondary frequency regulation cost of the energy storage is described by a quadratic function of the SOC offset and power.

[0010] The constraints include: constraints on the change in wind turbine output power, constraints on the change in energy storage device power, constraints on the state of charge of energy storage device, and constraints on the power balance condition of secondary frequency regulation.

[0011] Preferably, the objective function is as follows:

[0012]

[0013] In the formula, C wi,k C represents the secondary frequency regulation cost of the i-th wind turbine at time k; bj,k Let be the frequency regulation cost of the j-th energy storage unit at time k; n be the number of wind turbines; m be the number of energy storage units;

[0014] The secondary frequency regulation cost of the fan is calculated using the following formula:

[0015]

[0016] In the formula, C wi,k Let ΔP be the secondary frequency regulation cost of the i-th wind turbine at time k; wi,k For the secondary frequency regulation responsibility undertaken by the i-th wind turbine at time k, a wi This is the weighting coefficient for the increased frequency regulation cost of the i-th wind turbine due to power deviation;

[0017] The secondary frequency regulation cost of the energy storage is calculated using the following formula:

[0018]

[0019] In the formula C bj,k Let ΔP be the frequency regulation cost of the j-th energy storage unit at time k; bj,k The secondary frequency regulation responsibility undertaken by the j-th energy storage unit at time k; S j,k Let S be the SOC of the j-th energy storage unit at time k; j,0 This is the baseline value for SOC; a bj and b bj These are the weighting coefficients for the increased frequency regulation cost of the j-th energy storage unit due to high power and SOC offset.

[0020] Preferably, the secondary frequency regulation control based on the reference value of the wind turbine power change includes:

[0021] An AGC signal is added to the active power control stage of the secondary frequency regulation control of the wind turbine.

[0022] Based on the relationship between the wind turbine pitch angle and the active power of the wind turbine, the wind turbine pitch angle value is determined by taking the reference value of the wind turbine power change as the target and combining the AGC signal with the improved pitch angle control equation.

[0023] Based on the aforementioned wind turbine pitch value, the wind turbine pitch angle is controlled to achieve secondary frequency regulation control.

[0024] Preferably, the AGC signal includes at least one or more of the following control signals: pitch control, speed limiting control, and pitch angle compensation control.

[0025] Preferably, determining the wind turbine pitch angle value using the improved pitch angle control equation in conjunction with the AGC signal includes:

[0026] When the enable signal E0 is 0, pitch control is not triggered; when the enable signal E0 is 1, the pitch angle is increased to β0 by calculating β0.

[0027] When wind speed v≥v high At that time, the active power output is changed by adjusting the pitch angle;

[0028] When the enable signal E1 for pitch angle compensation control is 1, the pitch angle increment obtained based on the improved pitch angle control equation determines the secondary frequency regulation control signal issued by AGC to the wind farm controller; when E1 is 0, the wind turbine does not participate in frequency regulation.

[0029] Preferably, the relationship between the wind turbine pitch angle and the active power of the wind turbine is as follows:

[0030]

[0031] In the formula, P is the output power of the fan, ρ is the air density, and V is the air density. w Let A be the wind speed, A be the area of ​​rotation of the wind turbine blades, and C be the area of ​​rotation of the wind turbine blades. p The wind energy utilization coefficient is related to the tip speed ratio λ and the pitch angle β.

[0032] Preferably, the improved pitch angle control equation is as follows:

[0033] β ref =E1Δβ AGC +Δβ ω +E0β0

[0034] In the formula β ref For the improved pitch angle control reference value, β0 is the preset pitch angle during wind turbine unloading operation; assuming the initial load unloading of the wind turbine is k%, then β0 satisfies:

[0035]

[0036] In the formula C pmax The optimal wind energy utilization coefficient.

[0037] Preferably, the frequency modulation signal of the wind farm controller is calculated using the following formula:

[0038]

[0039] In the formula ΔP w P is the secondary frequency modulation control signal issued by AGC. set P represents the planned power output of the wind turbine. e To output electromagnetic power to the wind turbine, K p and K i These are the proportional gain coefficient and integral gain coefficient of the AGC controller for the pitch angle response system, respectively.

[0040] Preferably, the method further includes:

[0041] When frequency regulation is required, the frequency regulation control of the wind turbine is determined based on the wind speed range, and the output of the energy storage system is adjusted in conjunction with the frequency regulation control of the wind turbine.

[0042] Preferably, the wind speed range includes:

[0043]

[0044] In the formula: v is the wind speed; v in The cut-in wind speed for the fan; v out Cut off the wind speed for the fan; v low This is the critical value for the low to medium wind speed range; v high This is the critical value for the medium-to-high wind speed range.

[0045] Preferably, the step of determining the frequency regulation control of the wind turbine based on the wind speed range, and simultaneously adjusting the output of the energy storage system in conjunction with the frequency regulation control of the wind turbine, includes:

[0046] When the wind speed is in the low wind speed range or during the high wind speed period, virtual droop control is used for energy storage; when the wind speed is in the medium wind speed range, virtual inertial control is used for the wind turbine.

[0047] Determine whether the polarity of the frequency change rate has changed. If it has, the virtual inertial response process of the wind turbine ends, the wind turbine exits primary frequency regulation, and the energy storage output is gradually increased by adjusting the main control coefficient.

[0048] When the system frequency approaches stability, the power output mode of the energy storage is switched, and the energy storage exits frequency regulation once after a few seconds.

[0049] Preferably, the virtual inertial control of the fan includes determining the frequency-modulated output power of the fan using the following formula:

[0050]

[0051] In the formula, K w ΔP is the proportionality coefficient; w Δf represents the frequency regulation power of the fan; Δf represents the frequency deviation.

[0052] Preferably, the energy storage system employs virtual droop control, which includes determining the frequency regulation output of the energy storage system using the following formula:

[0053]

[0054] Where k1 is the coordination coefficient with the virtual inertial control of the wind turbine; k2 is the control coefficient related to the state of charge of the energy storage itself; k3 is the main control coefficient; K E T represents the unit regulation power of the energy storage system. E ΔP is the response time constant of the energy storage system. BESS s is the frequency regulation output of the energy storage system; s is the Laplace operator of the transfer function.

[0055] Preferably, the formula for calculating the coordination coefficient with the virtual inertial control of the wind turbine is as follows:

[0056] k1 = 1 - e -αt

[0057] In the formula, α is the adjustment coefficient; t is time.

[0058] The preferred control coefficients related to the state of charge of the energy storage system include: energy storage system charging control coefficients and energy storage system discharging control coefficients.

[0059] Preferably, the formula for calculating the charging control coefficient of the energy storage system is as follows:

[0060]

[0061] The formula for calculating the discharge control coefficient of the energy storage system is as follows:

[0062]

[0063] In the formula, k 2c The charging control coefficient for the energy storage system; k 2d S is the discharge control coefficient of the energy storage system. socis the SOC value of the energy storage system; m is the adjustment coefficient; sy1 is the SOC charging parameter, sy2 is the SOC discharging parameter; soc1, soc2, soc3, and soc4 are all SOC thresholds, and 0 < soc1 < soc2 < 1, 0 < soc3 < soc4 < 1.

[0064] Preferably, the main control coefficient k3 is adjusted according to the following formula:

[0065]

[0066] In the formula, k 3(0) ω0 is the inherent control coefficient; M is the conversion coefficient based on the rated power of the energy storage system; P(ω0) is the active power reference value of the wind turbine at the initial moment of frequency regulation; and P(t) is the real-time output power of the wind turbine during the speed recovery phase.

[0067] Preferably, the power output mode of the energy storage is switched according to the following formula:

[0068]

[0069] In the formula, ΔP E (t q ) for t q The output power of the stored energy at any given time; d is the coefficient of the power decay rate.

[0070] Based on the same inventive concept, this invention also provides a wind-storage combined power plant frequency regulation optimization control system, comprising:

[0071] The reference value determination module is used to determine the reference values ​​for wind turbine power change and energy storage power change with the goal of minimizing the cost of frequency modulation power supply participating in automatic power generation control.

[0072] The secondary frequency regulation control module is used to perform secondary frequency regulation control based on the reference values ​​of the wind turbine power change and the energy storage power change.

[0073] Preferably, the reference value determination module includes an objective function determination submodule;

[0074] The objective function determination submodule is used to construct an objective function with the goal of minimizing the cost of frequency modulation power supply participating in automatic generation control, and to determine the constraints for the objective function.

[0075] Among them, the minimum cost of the frequency-regulated power supply participating in automatic power generation control includes: the minimum secondary frequency regulation cost of each wind turbine and the minimum frequency regulation cost of each energy storage unit at the current moment; the secondary frequency regulation cost of the wind turbine is described by a quadratic function of the turbine offset power; the secondary frequency regulation cost of the energy storage is described by a quadratic function of the SOC offset and power.

[0076] The constraints include: constraints on the change in wind turbine output power, constraints on the change in energy storage device power, constraints on the state of charge of energy storage device, and constraints on the power balance condition of secondary frequency regulation.

[0077] Preferably, the secondary frequency modulation control module is specifically used for:

[0078] An AGC signal is added to the active power control stage of the secondary frequency regulation control of the wind turbine.

[0079] Based on the relationship between the wind turbine pitch angle and the active power of the wind turbine, the wind turbine pitch angle value is determined by taking the reference value of the wind turbine power change as the target and combining the AGC signal with the improved pitch angle control equation.

[0080] Based on the aforementioned wind turbine pitch value, the wind turbine pitch angle is controlled to achieve secondary frequency regulation control.

[0081] Preferably, the system further includes: a primary frequency modulation control module;

[0082] The primary frequency control module is used to determine the primary frequency control of the wind turbine based on the wind speed range, and at the same time adjust the output of the energy storage system in conjunction with the frequency control of the wind turbine.

[0083] Preferably, the primary frequency modulation control module is specifically used for:

[0084] When the wind speed is in the low wind speed range or during the high wind speed period, virtual droop control is used for energy storage; when the wind speed is in the medium wind speed range, virtual inertial control is used for the wind turbine.

[0085] Determine whether the polarity of the frequency change rate has changed. If it has, the virtual inertial response process of the wind turbine ends, the wind turbine exits primary frequency regulation, and the energy storage output is gradually increased by adjusting the main control coefficient.

[0086] When the system frequency approaches stability, the power output mode of the energy storage is switched, and the energy storage exits frequency regulation once after a few seconds.

[0087] Based on the same inventive concept, the present invention also provides a computer device, comprising: one or more processors;

[0088] The processor is used to store one or more programs;

[0089] When the one or more programs are executed by the one or more processors, the wind-storage combined power plant frequency regulation optimization control method provided by the present invention is implemented.

[0090] Based on the same inventive concept, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, it implements a wind-storage combined power plant frequency regulation optimization control method provided by the invention.

[0091] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0092] The wind-storage combined power station frequency regulation optimization control method and system proposed in this invention includes: during secondary frequency regulation, with the goal of minimizing the cost of the frequency regulation power supply participating in automatic power generation control, determining the reference value of wind turbine power change and the reference value of energy storage power change, and performing secondary frequency regulation control based on the reference values ​​of wind turbine power change and energy storage power change. This not only considers the state of charge of the energy storage power station itself, but also coordinates with the operating conditions of the wind turbine in real time, which can extend the service life of energy storage while improving the dynamic frequency characteristics of the system.

[0093] The wind-storage combined power plant frequency regulation optimization control method and system proposed in this invention can compensate for the insufficient output of the wind turbine in the later stage and avoid the problem of secondary frequency drop caused by the wind turbine during the primary frequency regulation by using energy storage. This effectively improves the frequency response characteristics of the system during the primary frequency regulation stage. Attached Figure Description

[0094] Figure 1 Control flowchart for wind-storage integrated system participating in primary frequency regulation;

[0095] Figure 2 This is a schematic diagram of the wind-storage combined power plant frequency regulation optimization control method of the present invention;

[0096] Figure 3 A schematic diagram of a wind turbine generator with an improved pitch angle structure participating in secondary frequency regulation control;

[0097] Figure 4 The s-curve is based on a simplified relationship between energy storage soc and k2;

[0098] Figure 5 This is a structural diagram of the wind-storage combined power plant frequency regulation optimization control system of the present invention. Detailed Implementation

[0099] To better understand this invention, the following description, in conjunction with the accompanying drawings and examples, will further illustrate the invention.

[0100] Example 1:

[0101] This invention provides a method for frequency regulation optimization control of a wind-storage combined power plant, including primary frequency regulation control and secondary frequency regulation control.

[0102] When primary frequency regulation is required, the frequency regulation control of the wind turbine is determined based on the wind speed range. Simultaneously, the output of the energy storage system is adjusted in conjunction with the wind turbine's frequency regulation control. First, based on the frequency response characteristics of the wind turbine, a wind speed segmentation method is proposed to determine the wind speed range in which the wind turbine participates in primary frequency regulation. Then, based on the frequency change characteristics of the inertial response and frequency recovery stages during primary frequency regulation, a joint wind-storage primary frequency regulation control strategy is proposed, such as... Figure 1 As shown, the specific steps include:

[0103] Step 1.1: First, detect the system frequency deviation at the current moment. If it exceeds the set frequency deviation dead zone |Δf|>0.033Hz, the first frequency adjustment process is initiated. Based on the inertial response characteristics of the fan releasing rotor kinetic energy at different wind speeds, a wind speed segment division method is proposed, specifically: wind speed v <v in and v>v out The fan does not participate in frequency regulation, where v in For the cut-in wind speed of the fan, v out Cut off the wind speed for the fan; v in ≤v≤v low This is the low wind speed range, where v low The critical value for the low to medium wind speed range can be taken as the wind speed corresponding to 20% of the fan's output power. The setting principle is that the fan speed during the release of rotor kinetic energy must not be lower than the minimum speed required for grid connection. low ≤v≤v high This is the medium wind speed range, where v high The critical value for the medium-to-high wind speed range can be taken as the wind speed corresponding to 95% of the fan's output power. The setting principle is that at high wind speeds, the fan's output power is limited and it cannot output the additional power required for frequency modulation; v high ≤v≤v out This is a high wind speed zone.

[0104] Step 1.2: Based on the wind speed segment division method in Step 1.1 above, it is proposed that in the medium wind speed segment, the wind turbine adopts virtual inertial control, and its frequency-modulated output is... Where K w ΔP is the proportionality coefficient. w Δf is the frequency regulation power of the wind turbine; when the wind turbine is in the low wind speed range and the high wind speed range, it cannot complete the inertial response, and the energy storage adopts virtual droop control to undertake its frequency regulation task.

[0105] Step 1.3: The energy storage system adopts virtual droop control for frequency regulation output ΔP BESS for Where k1, k2, and k3 are the coordination coefficients for the virtual inertial control of the wind turbine, the control coefficients related to the state of charge of the energy storage itself, and the main control coefficients, respectively; K ET represents the unit regulation power of the energy storage system. E is the response time constant of the energy storage system; s is the Laplace operator of the transfer function.

[0106] Step 1.4: k1 is the coordination coefficient with the virtual inertial control of the wind turbine, which is k1 = 1 - e -αt , where α is the adjustment coefficient and t is time, to avoid the wind turbine's output continuously decreasing during the inertial response phase, resulting in insufficient frequency support from the wind farm for the system;

[0107] Step 1.5: k2 is a control coefficient related to the state of charge of the energy storage itself, which can be expressed separately according to the charging and discharging operating modes as: Energy storage system charging control coefficient k 2c and energy storage discharge control coefficient k 2d The calculation formula is as follows:

[0108]

[0109]

[0110] In the formula, k 2c The charging control coefficient for the energy storage system; k 2d S is the discharge control coefficient of the energy storage system. soc Let Soc be the SOC value of the energy storage system; m be the adjustment coefficient; σc be the SOC charging parameter; σc be the SOC discharging parameter; socc1, socc2, socc3, and socc4 are all SOC thresholds, and 0 < socc1 < socc2 < 1, 0 < socc3 < socc4 < 1. Based on the simplified S-curve of the relationship between energy storage SOC and k2, as shown... Figure 4 As shown, when the system frequency fluctuation is small, shallow charging and discharging is typically performed within the SOC range of 40%-60% for energy storage; when the system frequency fluctuation is large, deep charging and discharging is performed, with the SOC range typically between 10%-90%. Therefore, SOC1, SOC2, SOC3, and SOC4 can be obtained. For example, SOC1 = 0.55, SOC2 = 0.9, SOC3 = 0.1, and SOC4 = 0.45. Thus, k is derived. 2c and k 2d The expression is as follows: sy1 represents the SOC charging parameter, and sy2 represents the SOC discharging parameter; determined empirically, these are taken as 0.725 and 0.275 respectively in this invention. Based on the above values, the charging control coefficient k of the energy storage system of this invention is... 2c and energy storage discharge control coefficient k 2d It can be specifically expressed as follows:

[0111] Energy storage system charging control coefficient

[0112] and discharge control coefficient

[0113] Step 1.6: Determine if the polarity of the frequency change rate has changed. If it has, the virtual inertial response process of the wind turbine ends, the wind turbine exits primary frequency regulation, and the speed begins to recover. To avoid the electromagnetic power jump causing impact on the system when the wind turbine exits frequency regulation, the output of the energy storage system gradually increases. This power deficit is compensated by dynamically adjusting k3. Where k 3(0) ω0 is the inherent control coefficient, M is the conversion coefficient based on the rated power of the energy storage system, P(ω0) is the active power reference value of the wind turbine at the initial moment of frequency regulation, and P(t) is the real-time output power of the wind turbine during the speed recovery phase.

[0114] Step 1.7: Smoothly exit the primary frequency regulation of the energy storage system, with the energy storage system operating at a frequency close to stable at time t. q The power output mode is switched during this process, and the energy storage output ΔP from step 1.2 is used. BESS Switch to Where ΔP E (t q ) for t q The output power of the energy storage at any given moment, where d is the coefficient of the power decay rate; after a few seconds, the energy storage exits the first frequency regulation, and the wind-storage combined first frequency regulation process ends.

[0115] The primary frequency regulation control strategy proposed in this invention releases rotor kinetic energy through virtual inertial control of the wind turbine to dampen the frequency drop during the inertial response stage, and compensates for the insufficient output reduction of the wind turbine in the later stage and avoids the problem of secondary frequency drop caused by the wind turbine through energy storage, effectively improving the frequency response characteristics of the system in the primary frequency regulation stage.

[0116] When secondary frequency modulation is required, such as Figure 2 As shown, it includes:

[0117] S1. When secondary frequency regulation is required, the reference values ​​for wind turbine power change and energy storage power change are determined with the goal of minimizing the cost of the frequency regulation power supply participating in automatic power generation control.

[0118] S2. Secondary frequency regulation control is performed based on the reference values ​​of the wind turbine power change and the energy storage power change.

[0119] Specifically, with the goal of minimizing the cost of frequency regulation power supply participating in automatic generation control, the reference values ​​for wind turbine power variation and energy storage power variation are determined as follows:

[0120] Step 2.1: Considering the wide applicability of wind speed and the large adjustable range of active power for wind turbine pitch angle control, pitch angle control is adopted in the secondary frequency regulation stage of the system, and the frequency regulation cost is described by a quadratic function of the unit offset power. Where C wi,kLet ΔP be the secondary frequency regulation cost of the i-th wind turbine at time k; wi,k For the secondary frequency regulation responsibility undertaken by the i-th wind turbine at time k, a wi This is the weighting coefficient for the increased frequency regulation cost of the i-th wind turbine due to power deviation;

[0121] Step 2.2: Energy storage uses a quadratic function of SOC offset and power to describe its frequency regulation cost. Where C bj,k Let ΔP be the frequency regulation cost of the j-th energy storage unit at time k; bj,k The secondary frequency regulation responsibility undertaken by the j-th energy storage unit at time k; S j,k Let S be the SOC of the j-th energy storage unit at time k; j,0 This is the baseline value for SOC; a bj and b bj These are the weighting coefficients for the increased frequency regulation cost of the j-th energy storage unit due to high power and SOC offset;

[0122] Step 2.3: Based on steps 2.1 and 2.2, the objective function at time k of frequency modulation is: The constraint condition is the constraint on the change in wind turbine output power P. wi,min ≤P wi,k ≤P wi,max Constraints on power variation of energy storage devices P bj,min ≤P bj,k ≤P bj,max State of charge constraints S of energy storage devices min ≤S j,k ≤S max Secondary frequency modulation power balance condition constraints The reference value ΔP for the change in wind turbine power is obtained by optimization. wi,k Reference value ΔP for changes in energy storage power bj,k .

[0123] The economically optimal allocation strategy proposed in this invention, which takes minimizing the cost of frequency regulation power supply participating in AGC as the objective function, not only considers the charge state of the energy storage power station itself, but also coordinates with the operating conditions of the wind turbine in real time. This can extend the service life of energy storage while improving the dynamic frequency characteristics of the system.

[0124] Secondary frequency regulation control is performed based on the reference values ​​of wind turbine power change and energy storage power change, such as... Figure 3 As shown, it specifically includes:

[0125] Step 3.1: Add AGC signals to the active power control stage of the wind turbine, mainly including pitch control, speed limiting control, and pitch angle compensation control. The improved pitch angle control equation is β. ref =E1Δβ AGC+Δβ ω +E0β0, where β ref For the improved pitch angle control reference value, β0 is the preset pitch angle during wind turbine unloading operation; assuming the initial load unloading of the wind turbine is k%, then β0 satisfies: In the formula C pmax The optimal wind energy utilization coefficient; the relationship between the pitch angle β and the active power of the wind turbine is as follows: Where P is the output power of the fan, ρ is the air density, and V is the air density. w Let A be the wind speed, A be the area of ​​rotation of the wind turbine blades, and C be the area of ​​rotation of the wind turbine blades. p The wind energy utilization coefficient is related to the tip speed ratio λ and the blade pitch angle β.

[0126] Step 3.2: Based on step 3.1, E0 is the enable signal in pitch load reduction control. When E0 is 0, β0 is 0 and pitch load reduction control is not triggered; when E0 is 1, the pitch angle is increased to β0 by calculating β0.

[0127] Step 3.3: Based on Step 3.1, Δβ ω For rotor speed limiting protection control, when the wind speed is too high, the blade pitch angle is adjusted by speed limiting control to reduce the active power output and maintain the speed near the rated value.

[0128] Step 3.4: Based on Step 3.1, Δβ AGC E1 is the pitch angle increment of the secondary frequency modulation signal of the pitch angle response system, and E1 is the enable signal for pitch angle compensation control. When E1 is 1, the wind turbine can respond to the frequency modulation signal sent by AGC to the wind farm controller. Where ΔP w P is the secondary frequency modulation control signal issued by AGC. set P represents the planned power output of the wind turbine. e To output electromagnetic power to the wind turbine, K p and K i These are the proportional gain coefficient and integral gain coefficient of the pitch angle response system AGC controller, respectively; when E1 is 0, the wind turbine does not participate in frequency regulation.

[0129] The secondary frequency regulation control strategy for wind turbines based on the improved pitch angle structure proposed in this invention makes full use of the speed of frequency regulation in wind farms and greatly improves the frequency response capability of the system.

[0130] Example 2:

[0131] To implement a method for frequency regulation optimization control of a wind-storage combined power plant, this invention also provides a control system for frequency regulation optimization of a wind-storage combined power plant, such as... Figure 5 As shown, it includes:

[0132] The primary frequency control module is used to determine the primary frequency control of the wind turbine based on the wind speed range, and at the same time, adjust the output of the energy storage system in conjunction with the frequency control of the wind turbine.

[0133] The reference value determination module is used to determine the reference values ​​for wind turbine power change and energy storage power change with the goal of minimizing the cost of frequency modulation power supply participating in automatic power generation control.

[0134] The secondary frequency regulation control module is used to perform secondary frequency regulation control based on the reference values ​​of the wind turbine power change and the energy storage power change.

[0135] The primary frequency modulation control module is specifically used for:

[0136] When the wind speed is in the low wind speed range or during the high wind speed period, virtual droop control is used for energy storage; when the wind speed is in the medium wind speed range, virtual inertial control is used for the wind turbine.

[0137] Determine whether the polarity of the frequency change rate has changed. If it has, the virtual inertial response process of the wind turbine ends, the wind turbine exits primary frequency regulation, and the energy storage output is gradually increased by adjusting the main control coefficient.

[0138] When the system frequency approaches stability, the power output mode of the energy storage is switched, and the energy storage exits frequency regulation once after a few seconds.

[0139] The reference value determination module includes an objective function determination submodule;

[0140] The objective function determination submodule is used to construct an objective function with the goal of minimizing the cost of frequency modulation power supply participating in automatic generation control, and to determine the constraints for the objective function.

[0141] Among them, the minimum cost of the frequency-regulated power supply participating in automatic power generation control includes: the minimum secondary frequency regulation cost of each wind turbine and the minimum frequency regulation cost of each energy storage unit at the current moment; the secondary frequency regulation cost of the wind turbine is described by a quadratic function of the turbine offset power; the secondary frequency regulation cost of the energy storage is described by a quadratic function of the SOC offset and power.

[0142] The constraints include: constraints on the change in wind turbine output power, constraints on the change in energy storage device power, constraints on the state of charge of energy storage device, and constraints on the power balance condition of secondary frequency regulation.

[0143] The secondary frequency modulation control module is specifically used for:

[0144] An AGC signal is added to the active power control stage of the secondary frequency regulation control of the wind turbine.

[0145] Based on the relationship between the wind turbine pitch angle and the active power of the wind turbine, the wind turbine pitch angle value is determined by taking the reference value of the wind turbine power change as the target and combining the AGC signal with the improved pitch angle control equation.

[0146] Based on the aforementioned wind turbine pitch value, the wind turbine pitch angle is controlled to achieve secondary frequency regulation control.

[0147] For details on the specific functions of each module in this embodiment, please refer to Embodiment 1, which will not be repeated here.

[0148] Example 3

[0149] Based on the same inventive concept, this invention also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement corresponding method flows or corresponding functions, thereby realizing the steps of the wind-storage combined power station participating in frequency regulation optimization control method in the above embodiments.

[0150] Example 4

[0151] Based on the same inventive concept, this invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the wind-storage combined power plant frequency regulation optimization control method in the above embodiments.

[0152] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0153] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0154] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0155] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0156] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0157] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A method for a wind and storage combined power station to participate in frequency modulation optimization control, characterized in that, The method comprises the following steps: When primary frequency modulation is needed, the wind turbine is controlled based on the interval of the wind speed, and the output of the energy storage system is adjusted in coordination with the frequency modulation control of the wind turbine; When secondary frequency modulation is needed, the wind turbine power change reference value and the energy storage power change reference value are determined by taking the minimum cost of the automatic generation control of the frequency modulation power supply as the target; Secondary frequency modulation control is performed based on the wind turbine power change reference value and the energy storage power change reference value; The interval of the wind speed comprises: wherein: is the wind speed; is the fan cut-in wind speed; is the fan cut-out wind speed; is the low-moderate wind speed segment threshold value; is the moderate-high wind speed segment threshold value; The wind turbine is controlled based on the interval of the wind speed, and the output of the energy storage system is adjusted in coordination with the frequency modulation control of the wind turbine, which comprises the following steps: When the wind speed is in the low wind speed section or the high wind speed section, the energy storage is controlled by virtual droop control; when the wind speed is in the medium wind speed section, the wind turbine is controlled by virtual inertia control; It is judged whether the polarity of the frequency change rate changes, if so, the virtual inertia response process of the wind turbine ends, the wind turbine exits the primary frequency modulation, and the output of the energy storage is gradually increased by adjusting the main control coefficient; When the system frequency tends to be stable, the power output mode of the energy storage is switched, and the energy storage exits the primary frequency modulation after a few seconds; The energy storage system is controlled by virtual droop control, which comprises the following steps: wherein, k 1 is the matching coefficient of the virtual inertia control of the wind turbine; k 2 is the control coefficient related to the state of charge of the energy storage itself; k 3 is the main control coefficient; K E is the unit regulation power of the energy storage system; T E is the response time constant of the energy storage system; Δ P BESS is the frequency modulation output of the energy storage system; s is the Laplace operator of the transfer function; is the frequency deviation.

2. The method of claim 1, wherein, The wind turbine power change reference value and the energy storage power change reference value are determined by taking the minimum cost of the automatic generation control of the frequency modulation power supply as the target, which comprises the following steps: A target function is constructed by taking the minimum cost of the automatic generation control of the frequency modulation power supply as the target, and constraint conditions are determined for the target function; The minimum cost of the automatic generation control of the frequency modulation power supply comprises the minimum secondary frequency modulation cost of each wind turbine at the current time and the minimum frequency modulation cost of each energy storage unit at the current time; the secondary frequency modulation cost of the wind turbine is described by a quadratic function of the unit deviation power; the secondary frequency modulation cost of the energy storage is described by a quadratic function of the SOC deviation and the power; The constraint conditions comprise the wind turbine output power change constraint, the energy storage device power change constraint, the state of charge constraint of the energy storage device, and the secondary frequency modulation power balance constraint.

3. The method of claim 2, wherein, The target function is as follows: In the formula, C wi,k is the second frequency modulation cost of the nth wind turbine at the t th moment; i k is the second frequency modulation cost of the nth wind turbine at the t th moment; C bj,k is the frequency modulation cost of the nth energy storage unit at the t th moment; j k is the frequency modulation cost of the nth energy storage unit at the t th moment; n is the number of wind turbines; m is the number of energy storage units;​​ The secondary frequency modulation cost of the wind turbine is calculated by the following formula: In the formula, C wi,k For the first i Each wind turbine unit k The cost of secondary frequency modulation at any given moment; Δ P wi,k For the first i Each wind turbine unit k The constant responsibility of secondary frequency modulation. a wi For the first i The weighting factor for increasing frequency regulation costs due to power deviation of individual wind turbine units; The secondary frequency modulation cost of the energy storage is calculated by the following formula: In the formula, C bj,k is the frequency modulation cost of the nth energy storage unit at the time instant t. j k t.​ Δ P bj,k For the first j Each energy storage unit in k The constant responsibility of secondary frequency modulation; S j,k For the first j Each energy storage unit in k SOC at any given moment; S j,0 This is the baseline value for SOC; a bj and b bj The first j The weighting factor for frequency regulation costs increases for each energy storage unit due to its high power and SOC offset.

4. The method of claim 1, wherein, The secondary frequency modulation control based on the wind turbine power change reference value comprises the following steps: An AGC signal is added to the active power control link of the wind turbine secondary frequency modulation control; The wind turbine power change reference value is taken as the target, and the wind turbine pitch angle value is determined by using an improved pitch angle control equation in combination with the AGC signal based on the relationship between the wind turbine pitch angle and the wind turbine active power; The wind turbine pitch angle is controlled based on the wind turbine pitch value to realize secondary frequency modulation control.

5. The method of claim 4, wherein, The AGC signal comprises one or more of the following control signals: variable-pitch load shedding control, speed limiting control, and pitch angle compensation control.

6. The method of claim 5, wherein, The wind turbine pitch angle and the wind turbine active power are related by the following formula: when the enable signal E 0 is 0, the pitch unloading control is not triggered; when the enable signal E 0 is 1, the pitch angle is increased to β 0 by calculating β 0, wherein β 0 is a preset pitch angle when the wind turbine is in unloading operation. When the wind speed is adjusted by adjusting the pitch angle to change the active output; When the pitch angle compensation control enables the signal E 1 is 1, the pitch angle increment based on the improved pitch angle control equation determines the secondary frequency control signal of the AGC reaching the wind farm controller; when E 1 is 0, the wind turbine does not participate in frequency modulation.

7. The method of claim 4, wherein, The improved pitch angle control equation is as follows: wherein P P is the output power of the wind turbine, The frequency modulation signal of the wind farm controller is calculated by the following formula: p is the air density, A A is the swept area of the wind turbine rotor during rotation, C p Cp is the wind energy utilization coefficient, which is related to the tip speed ratio ​ and the pitch angle β R is the radius of the wind turbine.

8. The method of claim 6, wherein, ​ In the formula β ref is an improved pitch angle control reference value, Δ β ω is a rotor speed limiting protection control, is a pitch angle increment of the pitch angle response system secondary frequency modulation signal; the initial load reduction of the wind turbine is set as k %, then β 0 satisfies: wherein C pmax is the best wind energy utilization coefficient, C p is the wind energy utilization coefficient.

9. The method of claim 8, wherein, ​ where Δ P w is a secondary frequency modulation control signal issued by the AGC, P set is a planned power of the wind turbine, P e is an electromagnetic power output of the wind turbine, K p and K i are respectively a proportional gain coefficient and an integral gain coefficient of a pitch angle response system AGC controller, is a power increment of the secondary frequency modulation signal.

10. The method of claim 9, wherein, The virtual inertia control of the wind turbine includes determining a frequency modulation output power of the wind turbine according to the following formula: In the formula, K w is a proportional coefficient; is the frequency-regulated power of the fan.

11. The method of claim 10, wherein, The calculation formula of the matching coefficient of the virtual inertia control of the wind turbine is as follows: In the formula, α is a modulation coefficient; t is time.

12. The method of claim 10, wherein, The control coefficient related to the state of charge of the energy storage system includes a charging control coefficient of the energy storage system and a discharging control coefficient of the energy storage system.

13. The method of claim 11, wherein, The calculation formula of the charging control coefficient of the energy storage system is as follows: The calculation formula of the discharging control coefficient of the energy storage system is as follows: In the formula, is a charging control coefficient of the energy storage system; is a discharging control coefficient of the energy storage system; S soc is an SOC value of the energy storage system; m is an adjustment coefficient; is an SOC charging parameter; is an SOC discharging parameter; are respectively threshold values of the SOC charging and discharging intervals, and , SOC is divided into a plurality of charging and discharging intervals according to 0, and 1.

14. The method of claim 10, wherein, The main control coefficient k3 is adjusted according to the following formula: wherein, k 3(0) is the inherent control coefficient; M is the conversion coefficient to the rated power of the energy storage system; P ω 0) is the active reference value of the fan at the initial time of frequency modulation, P (t) is the real-time output power in the fan speed recovery stage.​ 15. The method of claim 3, wherein, The power output mode of the energy storage is switched according to the following formula: In the formula, ΔP E (t q ) is the output power of the energy storage at time t q ; d is the coefficient of power decay rate; is the output power of the energy storage; is time.

16. A wind storage combined power station participates in frequency modulation optimization control system, characterized in that, The method comprises the following steps: a primary frequency modulation control module is configured to determine the primary frequency modulation control of the wind turbine based on the interval in which the wind speed is located, and to adjust the output of the energy storage system in cooperation with the frequency modulation control of the wind turbine; the interval in which the wind speed is located includes: wherein: V is the wind speed; Vcutin is the fan cut-in wind speed; Vcutout is the fan cut-out wind speed; Vcritmidlow is the critical value for the mid-low wind speed range; Vcritmidhigh is the critical value for the mid-high wind speed range; a reference value determination module is configured to determine a wind turbine power variation reference value and an energy storage power variation reference value with the minimum cost of the frequency modulation power source participating in automatic generation control as the target; a secondary frequency modulation control module is configured to perform secondary frequency modulation control based on the wind turbine power variation reference value and the energy storage power variation reference value; the primary frequency modulation control module is specifically configured to: when the wind speed is in a low wind speed section or a high wind speed section, virtual droop control is adopted for the energy storage; and when the wind speed is in a medium wind speed section, virtual inertia control is adopted for the wind turbine; it is determined whether the polarity of the frequency variation rate changes, and if the polarity changes, the virtual inertia response process of the wind turbine ends, the wind turbine exits the primary frequency modulation, and the output of the energy storage is gradually increased by adjusting the main control coefficient; when the system frequency tends to be stable, the power output mode of the energy storage is switched, and the energy storage exits the primary frequency modulation after a few seconds; the virtual droop control of the energy storage system includes determining the frequency modulation output of the energy storage system according to the following formula: wherein, k 1 is the matching coefficient of the virtual inertia control of the wind turbine; k 2 is the control coefficient related to the state of charge of the energy storage itself; k 3 is the main control coefficient; K E is the unit regulation power of the energy storage system; T E is the response time constant of the energy storage system; Δ P BESS is the frequency modulation output of the energy storage system; s is the Laplace operator of the transfer function; is the frequency deviation.

17. The system of claim 16, wherein, the reference value determination module includes a target function determination sub-module; the target function determination sub-module is configured to construct a target function with the minimum cost of the frequency modulation power source participating in automatic generation control as the target, and to determine a constraint condition for the target function; the minimum cost of the frequency modulation power source participating in automatic generation control includes the minimum secondary frequency modulation cost of each wind turbine at the current time and the minimum frequency modulation cost of each energy storage unit at the current time; the secondary frequency modulation cost of the wind turbine is described by a quadratic function of the unit deviation power; and the secondary frequency modulation cost of the energy storage is described by a quadratic function of the SOC deviation and the power; the constraint condition includes a wind turbine output power variation constraint, an energy storage device power variation constraint, an energy storage device state of charge constraint, and a secondary frequency modulation power balance condition constraint.

18. The system of claim 16, wherein, the secondary frequency modulation control module is specifically configured to: an AGC signal is added to the active power control link of the wind turbine secondary frequency modulation control; a wind turbine pitch angle value is determined by taking the wind turbine power variation reference value as the target, combining the AGC signal, and using an improved pitch angle control equation; the wind turbine pitch angle is controlled based on the wind turbine pitch angle value to realize secondary frequency modulation control.

19. A computer device, comprising: The method comprises the following steps: one or more processors; the processor is configured to store one or more programs; When the one or more programs are executed by the one or more processors, a method for a wind storage combined power station to participate in frequency modulation optimization control is implemented, as claimed in any one of claims 1 to 15.

20. A computer-readable storage medium, characterized in that, A computer program is stored thereon, and when the computer program is executed, a method for a wind storage combined power station to participate in frequency modulation optimization control is implemented, as claimed in any one of claims 1 to 15.

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