CN115940208A

CN115940208A - Wind power storage cooperative control and energy storage capacity configuration method and terminal

Info

Publication number: CN115940208A
Application number: CN202211493069.3A
Authority: CN
Inventors: 林伟伟; 林毅; 林威
Original assignee: State Grid Fujian Electric Power Co Ltd; Economic and Technological Research Institute of State Grid Fujian Electric Power Co Ltd
Current assignee: State Grid Fujian Electric Power Co Ltd; Economic and Technological Research Institute of State Grid Fujian Electric Power Co Ltd
Priority date: 2022-11-25
Filing date: 2022-11-25
Publication date: 2023-04-07

Abstract

The invention provides a method and a terminal for wind storage cooperative control and energy storage capacity configuration, wherein the method comprises the following steps: analyzing constraint conditions of frequency change indexes in the frequency response process of the system, and evaluating the frequency modulation requirement of the system according to the constraint conditions; determining a wind storage cooperative control strategy according to the system frequency modulation requirement, determining an energy storage capacity configuration scheme and setting the parameters of a wind storage controller by combining with the wind power grid-connected standard. According to the method, the frequency modulation requirement of the system is evaluated by analyzing the constraint condition of the frequency change index of the system subjected to power disturbance in the frequency response process, the wind-power storage cooperative control strategy and the energy storage capacity configuration scheme are provided according to the frequency modulation requirement of the system in combination with the wind-power grid-connection standard, and the parameters of the wind-power storage controller are set, so that the frequency change index is limited in safety constraint after wind storage is performed, the frequency safety is guaranteed, and the wind-power grid-connection requirement is met.

Description

Wind storage cooperative control and energy storage capacity configuration method and terminal

Technical Field

The invention relates to the technical field of new energy high-permeability power system frequency modulation demand assessment and control, in particular to a method and a terminal for wind storage cooperative control and energy storage capacity configuration.

Background

With the large-scale access of wind power to a power grid, the inertial support capability and the primary frequency modulation capability of the system are continuously reduced, and the frequency safety problem of the system after power disturbance is seriously influenced. The wind turbine generator and the energy storage device utilize the energy stored by the wind turbine generator and the energy storage device to participate in power response, and the frequency response characteristic of the system is improved. However, the specific output of the wind energy storage needs to be set according to the system frequency modulation requirement and the respective capacity ratio, and how the wind energy storage and the wind energy storage cooperate with each other to enable the output to meet the system frequency modulation requirement needs to be further researched. Therefore, how to evaluate the frequency modulation requirement of the system, and configure the energy storage capacity and configure the wind storage cooperative control strategy according to the evaluation result becomes a problem to be solved urgently.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the method and the terminal for wind power storage cooperative control and energy storage capacity configuration are provided, the frequency safety of the system is effectively guaranteed, and the wind power grid-connected requirement is met.

In order to solve the technical problems, the invention adopts the technical scheme that:

a method for wind storage cooperative control and energy storage capacity configuration comprises the following steps:

s1, analyzing constraint conditions of frequency change indexes in a system frequency response process, and evaluating system frequency modulation requirements according to the constraint conditions;

s2, determining a wind storage cooperative control strategy according to the system frequency modulation requirement;

s3, determining an energy storage capacity configuration scheme according to the system frequency modulation requirement and in combination with a wind power grid-connected standard;

and S4, setting parameters of the wind storage controller according to the system frequency modulation requirement.

In order to solve the technical problem, the invention adopts another technical scheme as follows:

a terminal for cooperative wind storage control and energy storage capacity configuration, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the following steps when executing the computer program.

and S4, setting parameters of the wind storage controller according to the frequency modulation requirement of the system.

The invention has the beneficial effects that: the invention provides a method and a terminal for wind storage cooperative control and energy storage capacity configuration, wherein the frequency modulation requirement of a system is evaluated by analyzing the constraint condition of a frequency change index of the system subjected to power disturbance in the frequency response process, a wind storage cooperative control strategy and an energy storage capacity configuration scheme are provided according to the frequency modulation requirement of the system by combining with the wind power grid-connection standard, and wind storage controller parameters are set, so that the frequency change index is limited in safety constraint after wind storage is output, the frequency safety is ensured, and the wind power grid-connection requirement is met.

Drawings

Fig. 1 is an overall flowchart of a method for wind storage cooperative control and energy storage capacity allocation according to an embodiment of the present invention;

FIG. 2 is a three-dimensional surface diagram of a system inertia demand evaluation result under a frequency change rate constraint according to an embodiment of the present invention;

FIG. 3 is a three-dimensional surface diagram of a system primary frequency modulation demand evaluation result under the constraint of frequency deviation according to the embodiment of the present invention;

FIG. 4 is a wind storage cooperative control block diagram based on system frequency modulation requirements in an embodiment of the present invention;

FIG. 5 is a simulation topology structure diagram of a wind power integration system in the embodiment of the present invention;

FIG. 6 is a frequency response curve under different controls according to an embodiment of the present invention;

FIG. 7 is a fan output curve of an embodiment of the present invention;

fig. 8 is a graph of energy storage output according to an embodiment of the present invention.

Fig. 9 is a schematic structural diagram of a terminal for wind storage cooperative control and energy storage capacity configuration according to an embodiment of the present invention;

description of reference numerals:

1. a terminal for wind storage cooperative control and energy storage capacity configuration; 2. a memory; 3. a processor.

Detailed Description

In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.

Referring to fig. 1 to 8, a method for wind storage cooperative control and energy storage capacity allocation includes the steps of:

As can be seen from the above description, the beneficial effects of the present invention are: the method comprises the steps of evaluating the frequency modulation requirement of a system by analyzing the constraint condition of the frequency change index of the system subjected to power disturbance in the frequency response process, extracting an air storage cooperative control strategy and an energy storage capacity configuration scheme according to the frequency modulation requirement of the system by combining with the wind power grid-connected standard, setting the parameters of a wind storage controller, limiting the frequency change index in safety constraint after wind storage output, ensuring frequency safety and meeting the wind power grid-connected requirement.

Further, the frequency variation index includes a frequency variation rate (df/dt) and a frequency deviation polarity value Δ f _max The system frequency modulation requirement comprises a system inertia requirement and a system primary frequency modulation requirement;

the step S1 specifically comprises the following steps:

s11, determining the constraint condition of the frequency change index, and limitingThe frequency change rate (df/dt) is within + -0.5 Hz/s, and the frequency deviation polarity value |. DELTA.f is defined _max |≤0.5Hz；

S12, evaluating the system frequency modulation requirement according to the constraint conditions of the frequency change rate and the frequency deviation polarity value, specifically:

using the system inertia time constant H _sys (unit s) represents the magnitude of the inertia requirement, and H is established _sys The relationship with (df/dt) is as follows:

wherein, Δ P _d Initializing power disturbance for the system;

the system inertial time constant H _sys Can be expressed as:

wherein H _min The minimum inertia requirement of the system is met;

according to the frequency deviation polarity value Deltaf _max Determining a frequency response equation of the system after the system is disturbed by power according to a constraint condition that | is less than or equal to 0.5 Hz:

wherein D is _sys Adjusting a small effect coefficient for a system load frequency, where Δ f is a system frequency deviation, Δ P _d For initial power disturbance of the system, Δ P _m Delta P is the amount of change in generator power _m Can be expressed as:

wherein, K _g For the primary frequency-modulation coefficient, T, of the synchronous machine _g Delay time for primary frequency modulation of synchronous machine；

Solving and analyzing the frequency response equation, and when the frequency change rate (df/dt) =0 and the frequency reaches an extreme value, determining the frequency deviation extreme value delta f _max Can be expressed as:

wherein, K _sys Is the system primary frequency modulation coefficient, t _max The time corresponding to the frequency extreme point, a, b, m and n are calculation parameters, then K _sys 、t _max A, b, m and n are respectively represented as:

wherein λ is _g The proportion of the capacity of the synchronous machine to the total capacity of the system is shown;

make the system inertia demand meet the system minimum inertia demand, H _sys ＝H _min When it is in contact with H _min Substituting the above equation (6) to obtain a, b, m and n as:

according to the above formula (7), when Δ f _max Can be regarded as only having Δ P _d And K _sys In this connection, at the frequency deviation polarity value |. DELTA.f _max Under the constraint condition that | is less than or equal to 0.5Hz, according to the initial power disturbance Delta P of the system _d Calculating the primary frequency modulation requirement K of the system _min Then, the primary frequency modulation coefficient of the system needs to satisfy all the time: k _sys ≥K _min 。

As can be seen from the above description, for the frequency change rate (df/dt), relevant studies at home and abroad indicate that the frequency change rate of the wind power high permeability system after receiving power disturbance should be limited within +/-0.5 Hz/s, and therefore, the maximum frequency change rate of the system after receiving power disturbance should meet the requirementThe above constraint condition; meanwhile, for the inertia requirement of the system, as the inertia represents the capability of hindering the frequency change after the power disturbance of the system occurs, the inertia time constant can be directly adopted to represent the inertia requirement, and the inertia requirement of the system is evaluated by establishing the relation between the inertia time constant and the frequency change rate, so that the frequency change rate is always smaller than the allowable value of the safe operation of the system under the action of the inertia; in addition to the frequency deviation polarity value Deltaf _max Because the primary frequency modulation capability of the system determines the frequency deviation polarity value after the system receives power disturbance, according to the regulation of the national standard GB/T15945-2008, the frequency deviation after the power system receives the power disturbance is not allowed to exceed 0.5Hz, namely the maximum frequency deviation after the system is subjected to the power disturbance also meets the constraint condition, so that the primary frequency modulation requirement of the system can be determined subsequently.

Further, the step S2 specifically includes:

when wind-powered electricity generation permeability crescent, control fan and energy storage provide frequency and support, specifically do:

s21, controlling the fan to participate in inertial response in a mode of releasing rotor kinetic energy so as to meet the inertia requirement of the system, and then displaying an inertia time constant H after the fan participates in the inertial response _{vir_w} Can be expressed as:

wherein, J _w Inherent moment of inertia of the fan, J _vir Is a virtual moment of inertia, P, of the fan _w Is the number of pole pairs of the fan S _w Rated capacity of the fan, H _w Is the inherent inertia time constant of the fan, delta omega _r Is the variation of the fan speed, omega _r0 Is the initial rotation speed before the inertial response of the fan, delta omega _e For synchronizing the rotational speed variations, ω _e The synchronous rotating speed is set;

s22, when the fan carries out the inertial response, the requirements are as follows:

and controlling the fan to exit the inertial response in a mode of additional differential control and introducing a time signal, and controlling the fan to exit the inertial response after the frequency falls to an extreme point according to the formula (9), wherein the method specifically comprises the following steps:

the time t when the frequency calculated in step S12 reaches the extreme point _max As the time for the fan to exit the inertial response;

and S23, controlling the energy storage to participate in primary frequency modulation under the droop control so as to meet the primary frequency modulation requirement of the system, and controlling the energy storage output to be 0 when the frequency recovers the reference value.

According to the description, when the wind power permeability shoulder pad is increased, the occupation ratio of the synchronous machine is reduced, so that the inertia and the primary frequency modulation capability of the system are insufficient, the fan and the stored energy are needed to provide frequency support, but the fan generally operates in the maximum power output state for ensuring economy, reserve capacity is not reserved, the fan usually cannot participate in primary frequency modulation, so that the fan only can participate in inertial response in a mode of releasing the kinetic energy of the rotor, and the inertia support capability of the system is improved; meanwhile, because the rotating speed of the fan is decoupled from the system frequency, the rotating speed of the fan can be changed in a rotating speed interval allowed by the safe operation when the fan participates in the inertial response, and the synchronous rotating speed is coupled with the system frequency, so that the fan needs to have the inertial support capacity similar to that of a synchronous machine through additional differential control to ensure the safety of the system frequency and even exceeds the inertia of the synchronous machine with the same capacity, the requirement of the system inertia can be met only by the fan performing the inertial response, and the requirement of the system on primary frequency modulation can be met only by performing primary frequency modulation on energy storage; in addition, the fan needs to retreat from the inertial response when the frequency falls to the extreme value so as to avoid the difficulty in frequency recovery caused by the fact that the fan absorbs energy in the system frequency recovery stage, but because the traditional differential control has high-frequency noise and cannot reasonably retreat through a frequency differential signal controller, a time signal is introduced on the basis of the differential control, and the time t when the frequency obtained by calculation in the step S12 reaches the extreme value is added _max As the time for the fan to exit the inertial responseThe fan can be timely withdrawn after the inertial response is finished, and the grid connection requirement is met; and different from the inertial response of the fan, when the stored energy participates in primary frequency modulation under droop control, as long as frequency deviation exists, the output force of the stored energy is always favorable for frequency recovery, and therefore when the frequency recovers to a reference value, the output force of the stored energy is also reduced to 0, and therefore the problem of exiting of the primary frequency modulation of the stored energy does not need to be considered.

Further, the step S3 specifically includes:

when the fan does not deload the operation and leads to the unable primary control of participating in of fan, adopt the energy storage to replace the fan to accomplish primary control, specifically do:

s31, under the condition that the constraint condition of the frequency deviation polarity value is determined according to the step S1, the primary frequency modulation requirement of the system depends on power disturbance, the maximum power disturbance of the system is set to be 20%, and then the primary frequency modulation requirement K of the system under the maximum power disturbance is calculated _min Configuring an energy storage capacity at the demand;

after the energy storage participates in the primary frequency modulation, the primary frequency modulation coefficient K of the system _sys Can be expressed as:

K _sys ＝D _sys +K _g ×λ _g +K _b ×λ _b (10)；

wherein λ is _b The ratio of the energy storage capacity to the total system capacity, K _b Is an energy storage controller parameter;

in order to meet the primary frequency modulation requirement K of the system _min Energy storage capacity ratio λ _b Can be expressed as:

according to the formula (11), the primary frequency modulation requirement K of the system is obtained under the condition of maximum power disturbance _min When the primary frequency modulation requirement K of the system can be met by substituting values of other parameters in the formula (11) _min Energy storage capacity of desired configuration, wherein, K _g Has a value range of 20 to 25 _sys Value range of (A)Is 0 to 1;

s32, taking K _g ＝20，D _sys =0, synchronous machine capacity ratio lambda for wind power high permeability system _g Can be controlled by the permeability lambda of the fan _w Is represented by lambda _g ＝1-λ _w While the stored energy participates in the primary frequency modulation by droop control, which supports the power P _b The size can be expressed as:

wherein, P _b Supporting power provided for energy storage, f _N To a nominal frequency, P _bn Rated power for storing energy.

From the above description, it can be known that, under the condition that the frequency deviation constraint is determined, the primary frequency modulation requirement of the system depends on power disturbance, for a microgrid with a small capacity, the maximum disturbance power of the microgrid can be derived from the maximum load fluctuation of the system or generator tripping, for a large-scale interconnected system, the maximum disturbance power of the microgrid can be derived from direct current blocking, so that the maximum power disturbance of the system is limited to 20%, and only the requirement K of the system on the primary frequency modulation coefficient under the maximum disturbance power needs to be calculated _min And then configuring the energy storage capacity according to the requirement.

Further, the step S4 specifically includes:

s41, when the fan adopts differential control and energy storage adopts droop control, setting the parameter of the fan controller as K _w Then, the inertia and the primary frequency modulation energy presented by the fan and the stored energy at this time can be expressed as:

wherein H _{vir_w} Virtual inertia time constant, K, exhibited after additional control of the fan _{vir_b} The size of primary frequency modulation coefficient shown after additional control for energy storage is realized, and the inertia time constant H of the system is at the moment _sys And the system primary frequency modulation coefficient K _sys Can be expressed as：

Wherein λ is _w The ratio of the fan capacity to the total system capacity, H _g Is the inertia time constant of the synchronous generator;

s42, according to the formula (14) and the system frequency modulation requirement evaluation result in the step S1, a fan controller parameter K _w And energy storage controller parameter K _b The following conditions are satisfied:

according to the description, the parameters of the wind storage are controlled regularly according to the frequency modulation requirement of the system, so that the frequency change rate and the frequency deviation are limited in the frequency safety constraint after the wind storage output, and the frequency safety is guaranteed.

Referring to fig. 9, a terminal for wind storage cooperative control and energy storage capacity configuration includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the following steps when executing the computer program:

As can be seen from the above description, the beneficial effects of the present invention are: based on the same technical concept, the wind storage cooperative control and energy storage capacity configuration method is matched, a wind storage cooperative control and energy storage capacity configuration terminal is provided, the frequency modulation requirement of the system is evaluated by analyzing the constraint condition of the frequency change index of the system subjected to power disturbance in the frequency response process, the wind storage cooperative control strategy and the energy storage capacity configuration scheme are provided according to the frequency modulation requirement of the system and the wind power grid-connection standard, the wind storage controller parameters are set, the frequency change index is limited in the safety constraint after the wind storage output, the frequency safety is guaranteed, and the wind power grid-connection requirement is met.

Further, the frequency variation indicator includes a frequency variation rate (df/dt) and a frequency deviation polarity value Δ f _max The system frequency modulation requirement comprises a system inertia requirement and a system primary frequency modulation requirement;

the step S1 specifically comprises the following steps:

s11, determining a constraint condition of the frequency change index, limiting the frequency change rate (df/dt) within +/-0.5 Hz/S, and limiting the frequency deviation polarity value | [ Delta ] f _max |≤0.5Hz；

wherein, Δ P _d Initializing power disturbance for the system;

the system inertial time constant H _sys Can be expressed as:

wherein H _min The minimum inertia requirement of the system is met;

wherein, K _g For the primary frequency-modulation coefficient, T, of the synchronous machine _g Delay time for primary frequency modulation of a synchronous machine;

according to the above formula (7), when Δ f _max Can be regarded as only having Δ P _d And K _sys In this connection, at the frequency deviation polarity value |. DELTA.f _max Under the constraint condition that | is less than or equal to 0.5Hz, according to the initial power disturbance Delta P of the system _d Calculating the primary frequency modulation requirement K of the system _min Then, the primary frequency modulation coefficient of the system needs to satisfy all the time: k is _sys ≥K _min 。

According to the description, related researches at home and abroad show that the frequency change rate (df/dt) of the wind power high permeability system after receiving power disturbance is limited within +/-0.5 Hz/s, so that the maximum frequency change rate of the system after receiving the power disturbance meets the constraint condition; meanwhile, for the inertia requirement of the system, as the inertia represents the capability of hindering the frequency change after the power disturbance of the system occurs, the inertia time constant can be directly adopted to represent the inertia requirement, and the inertia requirement of the system is evaluated by establishing the relation between the inertia time constant and the frequency change rate, so that the frequency change rate is always smaller than the allowable value of the safe operation of the system under the action of the inertia; in addition to the frequency deviation polarity value Deltaf _max Because the primary frequency modulation capability of the system determines the frequency deviation polarity value after the system receives power disturbance, according to the regulation of the national standard GB/T15945-2008, the frequency deviation after the power system receives the power disturbance is not allowed to exceed 0.5Hz, namely the maximum frequency deviation after the system is subjected to the power disturbance also meets the constraint condition, so that the primary frequency modulation requirement of the system can be determined subsequently.

Further, the step S2 specifically includes:

s21, controlling the fan to participate in inertial response in a mode of releasing rotor kinetic energy so as to meet the requirement of the inertia of the system, and displaying an inertia time constant H after the fan participates in the inertial response _{vir_w} Can be expressed as:

wherein, J _w Is the inherent moment of inertia of the fan, J _vir Is a virtual moment of inertia, P, of the fan _w Is the number of pole pairs of the fan S _w Rated capacity of the fan, H _w Is the inherent inertia time constant of the fan, delta omega _r Is the variation of the fan speed, omega _r0 Is the initial rotation speed before the inertial response of the fan, delta omega _e For synchronizing the rotational speed variations, omega _e The synchronous rotating speed is adopted;

and S23, controlling the stored energy to participate in primary frequency modulation under the droop control so as to meet the primary frequency modulation requirement of the system, and controlling the stored energy output to be 0 when the frequency recovers the reference value.

According to the description, when the wind power permeability shoulder pad is increased, the occupation ratio of the synchronous machine is reduced, so that the inertia and the primary frequency modulation capability of the system are insufficient, the fan and the stored energy are needed to provide frequency support, but the fan generally operates in the maximum power output state for ensuring economy, reserve capacity is not reserved, the fan usually cannot participate in primary frequency modulation, so that the fan only can participate in inertial response in a mode of releasing the kinetic energy of the rotor, and the inertia support capability of the system is improved; meanwhile, because the rotating speed of the fan is decoupled from the system frequency, the rotating speed of the fan can be changed in a rotating speed range allowed by safe operation when the fan participates in inertial response, and the synchronous rotating speed is coupled with the system frequency to ensure the systemThe system frequency is safe, the fan needs to have the inertial support capacity similar to that of a synchronous machine through additional differential control, even the inertia of the synchronous machine with the same capacity is far exceeded, so that the inertia requirement of the system can be met only by the fan performing inertial response, and the energy storage only needs to perform primary frequency modulation to meet the primary frequency modulation requirement of the system; in addition, the fan needs to retreat from the inertial response when the frequency falls to the extreme value so as to avoid the difficulty in frequency recovery caused by the fact that the fan absorbs energy in the system frequency recovery stage, but because the traditional differential control has high-frequency noise and cannot reasonably retreat through a frequency differential signal controller, a time signal is introduced on the basis of the differential control, and the time t when the frequency obtained by calculation in the step S12 reaches the extreme value is added _max The time for the fan to exit the inertial response is used, so that the fan can exit in time after the inertial response is finished; and different from the inertial response of the fan, when the energy storage participates in the primary frequency modulation under the droop control, as long as frequency deviation exists, the output force of the energy storage is always favorable for frequency recovery, therefore, when the frequency recovers to a reference value, the output force of the energy storage is also reduced to 0, and the problem of exiting of the primary frequency modulation of the energy storage does not need to be considered.

Further, the step S3 specifically includes:

after the stored energy participates in the primary frequency modulation, the primary frequency modulation coefficient K of the system _sys Can be expressed as:

K _sys ＝D _sys +K _g ×λ _g +K _b ×λ _b (10)；

according to the formula (11), the primary frequency modulation requirement K of the system is obtained under the maximum power disturbance _min When the primary frequency modulation requirement K of the system can be met by substituting values of other parameters in the formula (11) _min Energy storage capacity of desired configuration, wherein, K _g Has a value range of 20 to 25 _sys The value range of (a) is 0 to 1;

s32, taking K _g ＝20，D _sys =0, synchronous machine capacity ratio lambda for wind power high permeability system _g Permeability lambda of blower _w Is represented by lambda _g ＝1-λ _w While the stored energy participates in primary frequency modulation through droop control, which supports power P _b The size can be expressed as:

Further, the step S4 specifically includes:

s41, whenWhen the fan adopts differential control and the energy storage adopts droop control, the parameter of the fan controller is set as K _w Then, the inertia and the primary frequency modulation energy presented by the fan and the stored energy at this time can be expressed as:

wherein H _{vir_w} Virtual inertia time constant, K, shown after additional control of the fan _{vir_b} The size of primary frequency modulation coefficient shown after additional control for energy storage is realized, and the inertia time constant H of the system is at the moment _sys And the primary frequency modulation coefficient K of the system _sys Can be expressed as:

The method and the terminal for wind storage cooperative control and energy storage capacity configuration are suitable for making a wind storage cooperative control strategy and an energy storage capacity configuration scheme under a power grid accessed to a large-scale wind power system. The following examples are given for illustrative purposes.

Referring to fig. 1, a first embodiment of the present invention is:

in this embodiment, as shown in fig. 1, a method for wind storage cooperative control and energy storage capacity configuration includes the steps of:

s1, analyzing constraint conditions of frequency change indexes in a system frequency response process, and evaluating system frequency modulation requirements according to the constraint conditions.

And S2, determining a wind storage cooperative control strategy according to the system frequency modulation requirement.

And S3, determining an energy storage capacity configuration scheme according to the system frequency modulation requirement and in combination with the wind power grid-connected standard.

In the embodiment, the frequency modulation requirement of the system is evaluated by analyzing the constraint condition of the frequency change index of the system subjected to power disturbance in the frequency response process, the wind and storage cooperative control strategy and the energy storage capacity configuration scheme are provided according to the frequency modulation requirement of the system in combination with the wind power grid connection standard, and the parameters of the wind storage controller are set, so that the frequency change index is limited in the safety constraint after the wind storage output, the frequency safety is guaranteed, and the wind power grid connection requirement is met.

Referring to fig. 2 to fig. 8, a second embodiment of the present invention is:

based on the first embodiment, in this embodiment, the frequency change indicator in the system frequency response process includes a frequency change rate (df/dt) and a frequency deviation polarity value Δ f _max 。

The step S1 specifically comprises the following steps:

s11, first, a constraint condition of the frequency change index and a constraint condition of the frequency deviation polarity value need to be determined.

For the frequency change rate (df/dt), relevant researches at home and abroad show that the frequency change rate of the wind power high permeability system after receiving power disturbance is limited within +/-0.5 Hz/s, and for the frequency deviation polarity value delta f _max The national standard GB/T15945-2008 stipulates that the frequency deviation of the power system after power disturbance is not allowed to exceed 0.5Hz, so the frequency deviation polarity value | Δ f is defined _max The maximum frequency change of the system after power disturbance is less than or equal to 0.5HzThe rate and maximum frequency deviation should be based on the constraints described above.

And S12, evaluating system frequency modulation requirements according to the constraint conditions of the frequency change rate and the frequency deviation polarity value, wherein the system frequency modulation requirements comprise system inertia requirements and system primary frequency modulation requirements.

For the inertia requirement of the system, the inertia time constant H of the system can be adopted as the inertia represents the capacity of the system to block frequency change after power disturbance _sys (unit s) represents the magnitude of the inertia demand by establishing H _sys The relationship to (df/dt) is used to evaluate the inertia requirements of the system.

Because the system needs to ensure that the frequency change rate of the system is always smaller than the allowable value of safe operation of the system under the action of inertia, the maximum frequency change rate of the system after receiving power disturbance needs to be determined, the system only has inertia response at the initial moment of the power disturbance, and the frequency change rate of the system is the maximum at the moment, namely H _sys The relationship to (df/dt) can be expressed as:

wherein, Δ P _d A power perturbation is initiated for the system.

According to the analysis, the system inertia requirement is the system inertia time constant H _sys Can be expressed as:

wherein H _min The minimum inertia requirement of the system. Fig. 2 is a three-dimensional surface graph of a system inertia demand evaluation result under a frequency change rate constraint according to an embodiment of the present invention, and according to fig. 2, under a condition that a maximum frequency change rate constraint is determined, a system inertia demand can be determined according to a power disturbance magnitude. For example, when the system power disturbance takes 0.1pu, the corresponding system minimum inertia requirement is 5s.

Primary frequency modulation requirement for systemBecause the primary frequency modulation capability of the system determines the frequency deviation polarity value delta f after the system receives power disturbance _max According to the above-mentioned pair |. DELTA.f _max The power disturbance is determined, and if it is required to ensure that the frequency deviation of the system always meets the constraint condition, the frequency response equation of the system after the power disturbance can be expressed as:

wherein D is _sys Adjusting a small effect coefficient for a system load frequency, where Δ f is a system frequency deviation, Δ P _d For initial power disturbance, Δ P, of the system _m Is the generator power variation. Then Δ P _m Can be expressed as:

wherein, K _g For the primary frequency-modulation coefficient, T, of the synchronous machine _g The delay time is modulated for the primary frequency of the synchronous machine.

The frequency response equation of the system is solved and analyzed, when the frequency change rate (df/dt) =0 and the frequency reaches an extreme value, the frequency deviation extreme value delta f _max Can be expressed as:

wherein, K _sys Is the system primary frequency modulation coefficient, t _max And a, b, m and n are calculation parameters for the time corresponding to the frequency extreme point. Then K is _sys 、t _max A, b, m and n are respectively represented as:

wherein λ is _g For the ratio of the capacity of the synchronous machine to the total capacity of the system。

according to the above equation (7), where Δ f _max Can be regarded as only having Δ P _d And K _sys In relation to, at frequency deviation polarity value |. DELTA.f _max Under the constraint condition that | is less than or equal to 0.5Hz, according to the initial power disturbance Delta P of the system _d The primary frequency modulation requirement K of the system can be calculated _min Then, the primary frequency modulation coefficient of the system needs to satisfy all the time: k _sys ≥K _min 。

As shown in fig. 3, which is a three-dimensional surface diagram of a system primary frequency modulation requirement evaluation result under the constraint of frequency deviation according to the embodiment of the present invention, according to fig. 3, when the constraint of frequency deviation of the system is 0.5Hz and the power disturbance is 0.15pu, the primary frequency modulation requirement K of the system is obtained _min Is 13MW/Hz.

When the wind power permeability is gradually increased, the occupation ratio of the synchronous machine is reduced, the inertia of the system and the sequential frequency modulation capacity are insufficient, and therefore the fan and the stored energy need to be controlled to provide frequency support. Because the fan generally operates in a maximum power output state for ensuring economy, reserve capacity is not reserved, and primary frequency modulation cannot be participated in, the fan can only participate in inertial response in a mode of releasing rotor kinetic energy, and therefore inertia supporting capacity of a system is improved. Namely, step S2 specifically includes:

s21, controlling the fan to participate in inertial response in a mode of releasing rotor kinetic energy so as to meet the requirement of system inertia, wherein an inertia time constant H is shown after the fan participates in the inertial response _{vir_w} Can be expressed as:

wherein, J _w Is the inherent moment of inertia of the fan, J _vir Is the virtual moment of inertia, P, of the fan _w Is the number of pole pairs of the fan, S _w Rated capacity of the fan, H _w Is the inherent inertia time constant of the fan, delta omega _r Is the variation of the fan speed, omega _r0 Is the initial rotation speed before the inertial response of the fan, delta omega _e For synchronizing the rotational speed variations, ω _e Is the synchronous speed.

Because the rotating speed of the fan is decoupled from the system frequency, the rotating speed of the fan in the inertia response period can be changed in a rotating speed range allowed by the safe operation of the fan, the rotating speed change range is 0.7-1.1 pu, the synchronous rotating speed is coupled with the system frequency, the change range is 0.99-1.01 pu for ensuring the safety of the system frequency, and the fan can have inertia far exceeding that of a synchronous machine with the same capacity through additional differential control according to the formula (8). Therefore, the inertia response of the fan can meet the requirement of the system inertia, and the energy storage can meet the primary frequency modulation requirement of the system by frequency modulation in sequence.

S22, the wind turbine has similar inertia supporting capacity to the synchronous machine through additional differential control, and according to GB/T19963.1-2021 technical Specification for connecting a wind power plant to a power system, the wind turbine needs to meet the following requirements when in inertia response:

according to the formula (9), the fan needs to retreat from the inertia response when the frequency falls to an extreme point, so that the problem that the frequency recovery is difficult due to the absorption capacity of the fan in the system frequency recovery stage is avoided. However, since the conventional differential control has high-frequency noise and cannot reasonably exit through the control of the frequency differential signal, the embodiment introduces a time signal, i.e., the time t when the frequency calculated in step S12 reaches the extreme point, on the basis of the differential control _max As the time for the fan to exit the inertial response, the fan can exit in time after the inertial response is finished, and the grid connection requirement is met.

And different with the inertial response of fan, when the energy storage participated in primary frequency modulation under flagging control, as long as there is frequency deviation, the play of energy storage was favorable to the frequency to resume all the time, promptly:

and S23, controlling the stored energy to participate in primary frequency modulation under the droop control so as to meet the primary frequency modulation requirement of the system, and controlling the stored energy output to be 0 when the frequency recovers the reference value without considering the problem that the primary frequency modulation of the stored energy exits.

Based on the analysis, the wind storage cooperative control strategy based on the system frequency modulation requirement is provided, according to the system frequency modulation requirement, the fan carries out inertial response to meet the system inertia requirement, and quits when the frequency reaches an extreme point, and the stored energy is sequentially modulated to meet the primary frequency modulation requirement of the system.

When the fan does not deload operation and leads to the fan can't participate in primary frequency modulation, adopt the energy storage to replace the fan and accomplish primary frequency modulation, for satisfying the primary frequency modulation demand of system, energy memory' S capacity needs to be configured sufficiently, step S3 specifically does promptly:

s31, firstly, the energy storage needs to meet the frequency modulation requirement of the system, and the primary frequency modulation requirement of the system depends on power disturbance under the condition that the constraint condition of the frequency deviation polarity value is determined according to the step S1. For a microgrid with smaller capacity, the maximum disturbance power of the microgrid can come from the maximum load fluctuation of a system or a generator tripping machine, and the maximum load disturbance is generally 5% -20% of the total capacity of the system; for large interconnected systems, the maximum disturbance power may come from dc blocking, e.g., the power disturbance caused by the bejin dc transmission blocking accounts for 3.2% of the capacity of the grid in some province of east china in 2015. In summary, the maximum power disturbance of the system can be set to 20%, and only the primary frequency modulation requirement K of the system under the maximum power disturbance needs to be calculated _min And configuring the energy storage capacity under the requirement.

K _sys ＝D _sys +K _g ×λ _g +K _b ×λ _b (10)；

wherein λ is _b The ratio of the energy storage capacity to the total system capacity, K _b Is an energy storage controller parameter.

According to aboveThe formula (10) is shown, in order to meet the primary frequency modulation requirement K of the system _min Energy storage capacity ratio λ _b Can be expressed as:

according to the formula (11), the primary frequency modulation requirement K of the system is obtained under the maximum power disturbance _min When the frequency modulation is determined, values of other parameters in the formula (11) are substituted to calculate the requirement K of meeting the primary frequency modulation of the system _min Energy storage capacity of desired configuration, wherein, K _g Has a value in the range of 20 to 25 _sys The value range of (A) is 0 to 1.

S32, taking K _g ＝20，D _sys =0, synchronous machine capacity ratio lambda for wind power high permeability system _g Can be controlled by the permeability lambda of the fan _w Is represented by λ _g ＝1-λ _w While the stored energy participates in primary frequency modulation through droop control, which supports power P _b The size can be expressed as:

wherein, P _b Supporting power provided for energy storage, f _N At a nominal frequency, P _bn Rated power for storing energy. Because the frequency deviation of the system does not exceed 0.5Hz, the energy storage power support potential is exerted to the maximum extent, and the energy storage is supported by rated power when the power disturbance is large.

Substituting the parameters in the analysis into an energy storage capacity ratio expression to calculate:

in the face of maximum power disturbance, energy storage capacity ratio configuration requirement lambda under different wind power permeabilities _b1 As shown in table 1 below:

TABLE 1

Permeability lambda of wind power _w	Energy storage capacity duty ratio requirement lambda _b1
		20％	0
40％	2.41％
		60％	6.41％

According to table 1, when the wind power permeability is low, the requirement can be met only by the synchronous machine participating in primary frequency modulation, and when the wind power permeability is high, energy storage needs to be configured to participate in primary frequency modulation.

And secondly, the energy storage capacity configuration needs to meet the wind power grid-connected standard regulation. The specification of the primary frequency modulation capability of the fan in the technical specification of the wind power plant access power system is as follows: when the system frequency rises, the maximum 10% of the fan should be provided _wn A power support; when the system frequency is reduced, the maximum power of the fan can be increased by 6% _wn Power support of (2), wherein P _wn The rated power of the fan. Therefore, the capacity of stored energy should be not less than 10% _wn 。

According to the analysis, the energy storage capacity ratio configuration requirement lambda under different wind power permeabilities is obtained according to the wind power grid-connected standard _b2 As shown in table 2 below:

TABLE 2

According to the analysis, in order to meet the frequency modulation requirement and meet the wind power grid-connected standard, the capacity of the energy storage device is divided into lambda _b Can be expressed as:

λ _b ＝max{λ _b1 ,λ _b2 } (16)。

when the system capacity is known, the energy storage capacity may be configured according to the above equation (16).

Fig. 4 is a block diagram of the cooperative wind storage control based on the system frequency modulation requirement in this embodiment, where in fig. 4, f _rq As a frequency measurement, t ₀ For the moment of disturbance occurrence, f ₀ Is an initial value of frequency, S ₁ To select the switch, P _opt For fan power output under maximum power tracking control, P _{w_ref} For the reference value of the output power of the fan, P _{b_ref} For energy-storage output power reference value, P _{b_rq} To store initial power. In this embodiment, according to fig. 4, step S4 specifically includes:

s41, when the fan adopts differential control and the energy storage adopts droop control, setting the parameters of the fan controller and the parameters of the energy storage controller to be K respectively _w And K _b Then, the inertia and the primary frequency modulation energy exhibited by the fan and the stored energy at this time can be expressed as:

wherein H _{vir_w} Virtual inertia time constant, K, exhibited after additional control of the fan _{vir_b} The size of the primary frequency modulation coefficient is shown after additional control is carried out on the stored energy.

At this time, the inertia time constant H of the system _sys Sum system primary frequency modulation coefficient K _sys Can be expressed as:

wherein λ is _w The ratio of the fan capacity to the total system capacity, H _g To synchronize forThe generator inertia time constant is generally 5s.

after the system frequency modulation requirement is calculated according to the frequency change constraint and the system power disturbance, setting values of the fan controller parameter and the energy storage controller parameter under different wind power ratios can be obtained by substituting the system frequency modulation requirement into the formula (15).

As shown in fig. 5, the simulation topology structure diagram of the wind power grid-connected system in this embodiment is shown, and according to fig. 5, the simulation system includes two thermal power plants with capacities of 600MW, a wind power plant formed by connecting 400 doubly-fed wind power generation sets in parallel, and an energy storage device formed by a storage battery, where wind power permeability is 40%, and according to the energy storage capacity configuration scheme provided in this embodiment, the storage battery capacity is configured to 80MW × 30s.

By adding the wind storage cooperative control strategy based on the system frequency modulation requirement provided by the embodiment to the fan and the energy storage, the power disturbance of 300MW of load sudden increase of the system at the moment of 2s is set. I.e. DELTA P _d =0.15pu, at which disturbance the minimum inertia requirement H of the system is _min 7.5s, the primary frequency modulation requirement K of the system _min Is 13MW/Hz. When wind and storage do not participate in frequency modulation, i.e. K _w And K _b When the values are all 0, according to the formula (14), when the inertia time constant of the synchronous machine is 5s, the primary frequency modulation coefficient is 20MW/Hz, and the wind power permeability is 40%, the inertia time constant and the sequential frequency modulation coefficients of the system are 3s and 12MW/Hz, so that the frequency modulation requirement of the system is not met, and wind and storage additional control participates in frequency modulation. Substituting the system frequency modulation requirement into the formula (15) can obtain the controller parameter K of the fan and the stored energy at the moment _w And K _b The setting is respectively 22.5 and 25.

Fig. 6 shows frequency response curves of the present embodiment under different controls, and fig. 7 and 8 show output curves of the blower and the stored energy, respectively. According to FIG. 6, when wind and storage are not additionally controlled, the maximum frequency change rate of the system is-0.64 Hz/s, and the frequency change rate constraint is not satisfied; the extreme value of the frequency deviation is-0.68 Hz, and the frequency deviation constraint is not satisfied; when only the fan is additionally provided with virtual inertia control, according to the graph of fig. 7, the fan can increase output according to the frequency signal after disturbance occurs, the frequency change rate of the system can be reduced to-0.46 Hz/s within a safety constraint range, and the inertia support power of the fan can be quitted when the frequency reaches an extreme point. But at the moment, the extreme value of the frequency deviation of the system is-0.56 Hz, the frequency deviation constraint is still not met, and the inertia response exits at the extreme value point of the frequency, so that the improvement effect on the steady-state deviation of the frequency is not achieved; after the energy storage is additionally provided with primary frequency modulation control according to the system frequency modulation requirement, as shown in fig. 6 and 8, the energy storage can provide power support according to the system frequency deviation signal until the system frequency is restored to a steady-state value, the energy storage participates in frequency adjustment according to the system frequency modulation requirement, the frequency deviation extreme value can be reduced to-0.5 Hz, the frequency deviation safety constraint is met, and the frequency steady-state deviation is effectively reduced.

Referring to fig. 9, a third embodiment of the present invention is:

a terminal 1 for wind storage cooperative control and energy storage capacity configuration includes a memory 2, a processor 3, and a computer program stored on the memory 2 and executable on the processor 3, in this embodiment, the processor 3 implements the steps in the first embodiment or the second embodiment when executing the computer program.

In summary, according to the method and the terminal for wind storage cooperative control and energy storage capacity configuration provided by the invention, the frequency modulation requirement of the system is evaluated by analyzing the constraint condition of the frequency change index of the system after power disturbance in the frequency response process, and the wind storage cooperative control strategy and the energy storage capacity configuration scheme are provided according to the frequency modulation requirement of the system in combination with the wind power grid-connected standard, and the method sets the parameters of the wind storage controller according to the frequency modulation requirement of the system, so that the frequency change rate and the frequency deviation are limited within the frequency safety constraint after wind storage output, the frequency safety is ensured, and the frequency safety is ensured; and the exit of the fan inertia response at the moment corresponding to the frequency extreme point is realized by introducing a time signal, and the grid-connected requirement is met.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.

Claims

1. A method for wind storage cooperative control and energy storage capacity configuration is characterized by comprising the following steps:

2. A method according to claim 1, wherein the frequency variation indicators comprise frequency variation rate (df/dt) and frequency deviation polarity value af _max The system frequency modulation requirement comprises a system inertia requirement and a system primary frequency modulation requirement;

the step S1 specifically comprises the following steps:

wherein, Δ P _d Initializing power disturbance for the system;

the system inertial time constant H _sys Can be expressed as:

wherein H _min The minimum inertia requirement of the system is met;

according to the frequency deviation polarity value |. DELTA.f _max Determining a frequency response equation of the system after the system is disturbed by power according to a constraint condition that | is less than or equal to 0.5 Hz:

wherein D is _sys Adjusting a small effect coefficient for the system load frequency,. DELTA.f is the system frequency deviation,. DELTA.P _d For initial power disturbance, Δ P, of the system _m Is the generator power variation, then _m Can be expressed as:

according to the above formula (7), when Δ f _max Can be regarded as only having Δ P _d And K _sys In this connection, at the frequency deviation polarity value |. DELTA.f _max Under the constraint condition that | < 0.5Hz, disturbing delta P according to the initial power of the system _d Calculating the primary frequency modulation requirement K of the system _min Then, the primary frequency modulation coefficient of the system needs to always satisfy: k _sys ≥K _min 。

3. The method of claim 2, wherein the step S2 specifically comprises:

wherein, J _w Inherent moment of inertia of the fan, J _vir Is a virtual moment of inertia, P, of the fan _w Is the number of pole pairs of the fan, S _w Rated capacity of the fan, H _w Is the inherent inertia time constant of the fan, delta omega _r Is the variation of the fan speed, omega _r0 Is the initial rotation speed before the inertial response of the fan, delta omega _e For synchronizing the rotational speed variations, omega _e The synchronous rotating speed is set;

the time t when the frequency calculated in step S12 reaches the extreme point _max As the time at which the fan exits the inertial response;

4. The method of claim 3, wherein the step S3 specifically comprises:

when the fan does not carry the operation and leads to the unable primary control of participating in of fan, adopt the energy storage to replace the fan to accomplish primary control, specifically do:

K _sys ＝D _sys +K _g ×λ _g +K _b ×λ _b (10)；

s32, taking K _g ＝20，D _sys =0, synchronous machine capacity ratio lambda for wind power high permeability systems _g Can be controlled by the permeability lambda of the fan _w Is represented by lambda _g ＝1-λ _w While the stored energy participates in the primary frequency modulation by droop control, which supports the power P _b The size can be expressed as:

wherein, P _b Supporting power provided for energy storage, f _N At a nominal frequency, P _bn Rated power for storing energy.

5. The method of claim 4, wherein the step S4 specifically comprises:

s41, when the fan adopts differential control and the energy storage adopts droop control, setting the parameter of the fan controller as K _w Then, the inertia and the primary frequency modulation energy presented by the fan and the stored energy at this time can be expressed as:

wherein H _{vir_w} Virtual inertia time constant, K, exhibited after additional control of the fan _{vir_b} The size of primary frequency modulation coefficient shown after additional control for energy storage is realized, and the inertia time constant H of the system is at the moment _sys And the primary frequency modulation coefficient K of the system _sys Can be expressed as:

6. a terminal for wind storage cooperative control and energy storage capacity configuration, comprising a memory, a processor and a computer program stored on the memory and operable on the processor, wherein the processor implements the following steps when executing the computer program:

7. A terminal for wind-storage cooperative control and energy storage capacity allocation according to claim 6, wherein the frequency variation index includes frequency variation rate (df/dt) and frequency deviation polarity value Δ f _max The system frequency modulation requirement comprises a system inertia requirement and a system primary frequency modulation requirement;

the step S1 specifically comprises the following steps:

s11, determining a constraint condition of the frequency change index, limiting the frequency change rate (df/dt) within +/-0.5 Hz/S, and limiting the frequency deviation polarity value (delta f) _max |≤0.5Hz；

using the system inertia time constant H _sys (unit s) represents the magnitude of the inertia demand, establish H _sys The relationship with (df/dt) is as follows:

wherein, Δ P _d Initializing power disturbance for the system;

the system inertial time constant H _sys Can be expressed as:

wherein H _min The minimum inertia requirement of the system is met;

according to said frequency deviationExtreme difference value Deltaf _max Determining a frequency response equation of the system after the system is disturbed by power according to a constraint condition that | is less than or equal to 0.5 Hz:

wherein D is _sys Adjusting a small effect coefficient for a system load frequency, where Δ f is a system frequency deviation, Δ P _d For initial power disturbance, Δ P, of the system _m Is the generator power variation, then _m Can be expressed as:

wherein, K _sys Is the primary frequency modulation coefficient, t, of the system _max The time corresponding to the frequency extreme point, a, b, m and n are calculation parameters, then K _sys 、t _max A, b, m and n are respectively represented as:

according to the above formula (7), when Δ f _max Can be regarded as only having Δ P _d And K _sys In connection with, at said frequency deviation polarity value |. DELTA.f _max Under the constraint condition that | is less than or equal to 0.5Hz, according to the initial power disturbance Delta P of the system _d Calculating the primary frequency modulation requirement K of the system _min Then, the primary frequency modulation coefficient of the system needs to always satisfy: k _sys ≥K _min 。

8. The terminal for wind-storage cooperative control and energy storage capacity configuration according to claim 7, wherein the step S2 specifically comprises:

wherein, J _w Is the inherent moment of inertia of the fan, J _vir Is the virtual moment of inertia, P, of the fan _w Is the number of pole pairs of the fan, S _w Rated capacity of the fan, H _w Is the inherent inertia time constant of the fan, delta omega _r Is the variation of the fan speed, omega _r0 Is the initial rotation speed before the inertial response of the fan, delta omega _e For synchronizing the rotational speed variations, omega _e The synchronous rotating speed is adopted;

9. The terminal for wind-storage cooperative control and energy storage capacity configuration according to claim 8, wherein the step S3 specifically comprises:

s31, under the condition that the constraint condition of the frequency deviation polarity value is determined according to the step S1, the primary frequency modulation requirement of the system depends on power disturbance, the maximum power disturbance of the system is set to be 20%, and only the primary frequency modulation requirement K of the system under the maximum power disturbance needs to be calculated _min Configuring an energy storage capacity at the demand;

K _sys ＝D _sys +K _g ×λ _g +K _b ×λ _b (10)；

according to the formula (11), the primary frequency modulation requirement K of the system is obtained under the condition of maximum power disturbance _min When the primary frequency modulation requirement K of the system can be met by substituting values of other parameters in the formula (11) _min Energy storage capacity of desired configuration, wherein, K _g Has a value in the range of 20 to 25 _sys The value range of (A) is 0 to 1;

10. The terminal for cooperative wind-storage control and energy storage capacity configuration according to claim 9, wherein the step S4 specifically comprises:

wherein H _{vir_w} Virtual inertia time constant, K, exhibited after additional control of the fan _{vir_b} Additional control for energy storageThen showing the magnitude of primary frequency modulation coefficient, at the moment of inertia time constant H of the system _sys And the system primary frequency modulation coefficient K _sys Can be expressed as: