CN114884085A - Frequency modulation method and system for flywheel energy storage of multi-direct-current feed-in receiving-end power grid - Google Patents

Frequency modulation method and system for flywheel energy storage of multi-direct-current feed-in receiving-end power grid Download PDF

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CN114884085A
CN114884085A CN202210372605.8A CN202210372605A CN114884085A CN 114884085 A CN114884085 A CN 114884085A CN 202210372605 A CN202210372605 A CN 202210372605A CN 114884085 A CN114884085 A CN 114884085A
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energy storage
frequency
flywheel energy
power grid
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李�杰
孟高军
周煜
孙玉坤
刘海涛
袁野
刘宇
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Nanjing Institute of Technology
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Nanjing Institute of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/30—Arrangements for balancing of the load in a network by storage of energy using dynamo-electric machines coupled to flywheels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/16—Mechanical energy storage, e.g. flywheels or pressurised fluids

Abstract

A frequency modulation method and a system for flywheel energy storage of a multi-direct-current feed-in receiving-end power grid belong to the technical field of receiving-end power grid energy storage frequency control methods, and comprise the following steps: monitoring the fluctuation of the frequency value of the receiving-end power grid in real time, acquiring the difference value between the frequency value of the receiving-end power grid and the standard frequency, and inputting the difference value into a data processing system; and judging whether the difference value exceeds the limit, predicting the power change of the power grid in a short period by a short-time-limit state disturbance estimation algorithm according to the difference value, constructing a power state prediction fitness function, and adjusting the working state of the flywheel energy storage unit to the optimal parameter by the flywheel energy storage control system according to an automatic power generation control strategy for improving conditions. The system monitors the frequency of the power grid in real time and switches the working state and the output of the flywheel energy storage unit, so that the frequency is always kept in a certain range. The invention enhances the frequency stability of the receiving-end power grid accessed by high-proportion new energy, and enables the frequency modulation to be more flexible and accurate.

Description

Frequency modulation method and system for flywheel energy storage of multi-direct-current feed-in receiving-end power grid
Technical Field
The invention belongs to the technical field of energy storage frequency control methods of receiving-end power grids, and particularly relates to a frequency modulation method and a frequency modulation system for flywheel energy storage of a multi-direct-current feed-in receiving-end power grid.
Background
Frequency is one of the important indicators for measuring the quality of electric energy. For the power grid, the frequency fluctuation of the system reflects the balance condition of power supply and demand, the power generation is larger than the load consumption, the system frequency is increased, the load consumption is larger than the power generation, and the system frequency is reduced. Frequency variations in the power system can have adverse effects on the customer, the power plant, and the power system itself, so the frequency must be maintained at a nominal value of 50Hz and below, and the offset cannot exceed a certain range. With the increase of a large number of new energy generator sets connected to a power grid and having impact loads, in order to ensure safe and economic operation of the power grid and improve the power utilization quality of users, the frequency modulation requirement of the power grid on the generator sets is higher and higher. At present, in each large regional power grid in China, large hydroelectric and thermal power units are main frequency modulation power supplies, and the frequency change of a system is responded by continuously adjusting the output of the frequency modulation power supplies, but each of the large hydroelectric and thermal power units has certain limitations and defects and influences the safety and quality of the power grid frequency. The problem of insufficient capacity of the existing frequency modulation is obvious, and a new frequency modulation means is urgently needed.
With the continuous improvement of the direct-current transmission power, the impact of the direct-current fault on the power grid is larger and larger, the problem of frequency or power angle stability can be caused, and voltage instability can be caused in severe cases. However, with the rapid development of extra-high voltage ac/dc, the existing control means and measures for feeding multiple dc into the receiving-end power grid cannot meet the requirements of wide-area consumption of clean energy and guarantee of operation safety of the power grid. In order to solve the above problems, countermeasures have to be found, and a method and a system for controlling frequency modulation of flywheel energy storage based on a short-time state disturbance estimation algorithm are researched and developed to solve the problem of frequency stability of a multi-dc feed receiving-end power grid.
The battery energy storage system has the characteristics of quick response and accurate tracking, so that the battery energy storage system is more efficient than the traditional frequency modulation means. In recent years, large-scale energy storage systems have been receiving attention in the industry to replace power plants for frequency modulation. Compared with the traditional power supply, the energy storage has obvious technical advantages of providing frequency modulation for the power grid, and the economy is gradually presented, so that the operating efficiency of the power system can be effectively improved. Flywheel Energy Storage (FES) is an advanced physical Energy Storage technology, and refers to an Energy Storage mode in which a Flywheel is driven by electric Energy to rotate at a high speed, the electric Energy is converted into mechanical Energy, and when needed, a motor is dragged by inertia of the Flywheel to generate electricity, so that the stored mechanical Energy is converted into electric Energy to be output (so-called Flywheel discharge). The power amplifier has the characteristics of high power density, high response speed, long service life, no maintenance, good expandability, no pollution and the like. Compared with other types of energy storage modes, such as lithium batteries, lead-acid batteries, pumped storage and the like, the flywheel energy storage power station has the advantages of high output power, high instantaneous response speed, low long-term operation and maintenance cost, safety, reliability, environmental friendliness, no pollution and the like. Particularly, the discharge power response speed of the flywheel energy storage system is high, the millisecond level is achieved, the requirement of primary frequency modulation control can be met, and the primary frequency modulation control can be carried out by combining the flywheel energy storage and the unit.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method and a system for frequency modulation of flywheel energy storage of a multi-direct-current feed-in receiving-end power grid.
In order to achieve the purpose, the invention adopts the following technical scheme:
a frequency modulation method for flywheel energy storage of a multi-direct-current feed-in receiving-end power grid is characterized by comprising the following steps:
step 1: monitoring the fluctuation of the frequency value of the receiving-end power grid in real time, and acquiring the difference value between the frequency value of the receiving-end power grid and the standard frequency;
step 2: judging whether the difference value exceeds the limit or not, predicting power variation of the power grid in a short period by a disturbance estimation algorithm according to the difference value, and searching the optimal state and parameters of the flywheel energy storage unit;
and step 3: and adjusting the state and the parameters of the flywheel energy storage unit through an automatic power generation control strategy according to the optimal state and the parameters to keep the frequency of the flywheel energy storage unit within a set range.
In order to optimize the technical scheme, the specific measures adopted further comprise:
further, in the step 2, when the difference value is within the upper limit and the lower limit, the flywheel energy storage unit works in an energy holding state in a short time; when the difference value is higher than the upper limit, the flywheel energy storage unit works in a charging state; when the difference value is lower, the flywheel energy storage unit works in a discharging state.
Further, in step 2, the power change of the power grid in a short term is predicted by a disturbance estimation algorithm according to the difference, and the optimal state and parameters of the flywheel energy storage unit are searched, specifically as follows:
step 2.1: screening frequency difference values delta f acquired within a short time limit (second level, such as between 10 and 15 seconds) to form a 2 multiplied by N matrix, wherein each element x (i, j) (i is less than or equal to 2, j is less than or equal to N) in the matrix is regarded as a state disturbance quantity, and the numerical fluctuation among the difference values is within [0, 2 ];
step 2.2: processing a matrix formed by the frequency difference value delta f by adopting a Gauss Seidel method, taking the processed frequency difference value as an initial value, and generating an initial state by adopting an embedded Chebyshev mapping chaotic sequence;
step 2.3: designing a power state prediction fitness function for predicting power change of the power grid in a short term;
step 2.4: and (4) predicting a fitness function based on the power state, and searching the optimal working state and parameters of the energy storage unit.
Further, the power state prediction fitness function is:
Figure BDA0003588636990000021
in the formula, f (u, v) is a state parameter function of the flywheel energy storage unit, u represents a state, v represents a parameter, and u represents a discharging state, an energy holding state and a charging state when the value of u is-1, 0 and 1 respectively; g (x, y) is a function of frequency time; h (z, y) is an active load time function.
Further, in step 2.4, the process of finding the optimal working state and parameters of the energy storage unit is as follows:
the initial state parameter function of the flywheel energy storage unit is f 0 (u, v) adding a disturbance amount (Δ u, Δ v), the state parameter function after adding disturbance being f i+1 (u，v)＝f i (u+Δu i ，v+Δv i ) In a corresponding state, g is obtained i+1 (x, y), the index i indicates the number of iterations; designing an optimal solution memory when the value of G (f (u, v)) is larger than the set value
Figure BDA0003588636990000033
When f is corresponding to n (u, v) are stored in a memory, the subscript n represents the nth iteration, G (f (u, v)) corresponding to the state parameter function of each unit is compared with G (f (u, v)) corresponding to the state parameter function of the memory, and if the value of G (f (u, v)) is larger than the value of the memory, the G (f (u, v)) replaces the state parameter function f (u, v)) in the memory n (u, v), then 2X 10 4 And outputting the optimal state and parameters after secondary disturbance.
Further, in step 3, the automatic power generation control strategy is specifically as follows:
in the control time domain, the occupation ratios of the unit in the charging state and the unit in the discharging state are lambda and mu respectively, and the expression is as follows:
Figure BDA0003588636990000031
Figure BDA0003588636990000032
in the formula, P RECN (k) And P DISCN (k) Respectively predicting the charging power and the discharging power of the flywheel energy storage unit at the moment k; n is a radical of REC (k) And N DISC (k) The number of the charging state machine set and the number of the discharging state machine set at the moment k are respectively;
the constraints are as follows:
-P BN ≤P B (k)≤P BN
ηN T ≤N REC (k)≤θN T ，ηN T ≤N DISC (k)≤θN T
0≤ΔN REC ≤θN T
0≤ΔN DISC ≤θN T
20％≤λ≤70％，20％≤μ≤70％，λ+μ≤80％
in the formula, P B (k) The output power of the flywheel energy storage system at the moment k; p BN The rated power of the flywheel energy storage system; n is a radical of T The total number of the flywheel energy storage units; η and θ are values less than 1, and η < θ; delta N REC The value of the change of the state of the unit in the charging state; delta N DISC The value is the changed value of the state of the unit in the discharging state.
Further, in step 3, the flywheel energy storage unit is controlled through constraint conditions according to the optimal state and parameters, so that the frequency is within the set upper and lower limit ranges.
The invention further provides a frequency modulation system for flywheel energy storage of a multi-direct-current feed-in receiving-end power grid, which is characterized by comprising the following components:
the data acquisition module is used for acquiring the frequency value of the receiving-end power grid and obtaining the difference value between the frequency value of the receiving-end power grid and the standard frequency through processing;
the data processing module is used for processing the input difference value, predicting power variation of the power grid in a short term by a disturbance estimation algorithm according to the difference value and outputting the optimal state and parameters of the flywheel energy storage unit;
and the unit working state adjusting module is used for adjusting the state and the parameters of the flywheel energy storage unit through an automatic power generation control strategy according to the output optimal state and the output optimal parameters, so that the frequency of the flywheel energy storage unit is kept within a set range.
The invention further provides a computer-readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute the method for frequency modulation of flywheel energy storage of a multi-dc-fed receiving-end power grid as described above.
The invention further provides an electronic device, which is characterized by comprising: the frequency modulation method for the flywheel energy storage of the multi-direct-current feed receiving-end power grid is realized when the processor executes the computer program.
The invention has the beneficial effects that: the invention effectively utilizes the flywheel energy storage system to store and release electric energy, transfers the flywheel energy storage unit to improve the frequency stability of the receiving-end power grid under the background of multi-direct-current feed-in through charging and discharging, realizes efficient primary frequency modulation by utilizing the advantage of high discharge power response speed of the flywheel energy storage system, improves the frequency stability of the receiving-end power grid accessed by high-proportion new energy, leads the frequency modulation to be more flexible and accurate, and improves the consumption capacity of the power grid to the new energy.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
Fig. 2 is a schematic diagram of a power grid structure based on a flywheel energy storage system.
Fig. 3 is a wiring diagram of the flywheel energy storage system of the present invention.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings.
The frequency modulation method for flywheel energy storage of a multi-direct current feed receiving-end power grid shown in fig. 1 mainly comprises the following three steps.
Step 1: and monitoring the fluctuation of the frequency value of the receiving-end power grid in real time, and acquiring the difference value delta f between the frequency value of the receiving-end power grid and the standard frequency.
Step 2: judging whether the difference value delta f exceeds the limit or not, predicting the power change of the power grid in a short period by a short-time-limit state disturbance estimation algorithm according to the difference value delta f, and searching the optimal state and parameters of the flywheel energy storage unit;
when the difference value is within the upper limit and the lower limit, the flywheel energy storage unit works in an energy holding state in a short period; when the difference value is higher than the upper limit, the system adjusts the flywheel energy storage unit to work in a charging state to an optimal parameter according to the predicted result of the power change of the power grid in a short period; when the difference value is lower, the system adjusts the working and discharging states of the flywheel energy storage unit to optimal parameters according to the predicted result of power change of the power grid in a short period.
In an embodiment, the flywheel energy storage unit may be a single flywheel energy storage system with fixed capacity or a flywheel array energy storage system with large-scale capacity expansion. The structure of the power grid based on the flywheel energy storage system is shown in fig. 2, and the wiring diagram of the flywheel energy storage system is shown in fig. 3.
The short-time-limit state disturbance estimation algorithm comprises the following steps:
a. numerical value encoding: and screening the frequency difference value delta f acquired within a short time limit to form a 2 multiplied by N matrix, wherein each element x (i, j) (i is less than or equal to 2, j is less than or equal to N) in the matrix is regarded as a state disturbance quantity, and the numerical fluctuation among the difference values is a numerical value within [0, 2 ].
b. Initializing a system state: in order to avoid the problem of low convergence speed caused by random initialization of the system state, the frequency value processed by the traditional Gauss Seidel method is used as an initial value, and an embedded Chebyshev (Chebyshev) mapping chaotic sequence is used for generating the initial state. Data X processed by Gauss Seidel method 0 As an initial value, X 0 Is a matrix whose elements are frequency differences of short duration, X 0 Each element x in (1) 0 (i, j) mapping to the interval [0, 100 ]]In the interval of (a) to (b),
Figure BDA0003588636990000051
in the formula, x 0 (i, j) is a frequency difference matrix X 0 Of the elements (a).
With X 0 As an initial value, obtaining a matrix X by utilizing Chebyshev chaotic mapping L (L ═ 1, 2.., K), then X L Value x of element (1) L (i, j) sequence obtained by inverse mapping:
X K ＝0+(100-0)X L (2)
in the formula, X K Is a new sequence obtained by inverse mapping for K times.
The frequency difference values are chaotic disturbed on the original basis, the diversity of the initial state is ensured by the ergodicity of the chaotic disturbance, the continuity of the change of the frequency difference values is also ensured to a certain extent, and the frequency change rule in the power system is better fitted.
c. Designing a power state prediction fitness function: the method is used for solving the optimal running state and parameters of the energy storage unit, the optimal running state can be compared with various different running states and parameters to judge whether the optimal running state is optimal or not, the running state and the parameters which need to be adjusted of the energy storage unit are unknown quantities in the real situation, the frequency is in a stable state within a short time limit, namely the frequency time function g (x, y) before the frequency difference value is not out of limit, and the active load time function h (z, y) are used for analyzing, and the h (z, y) can be calculated according to a daily load curve according to the power grid load before the frequency difference value is out of limit. And obtaining a short-time-limit frequency time function g '(x, y) according to the adjusted state and parameter f (u, v) of the energy storage unit, and when the g' (x, y) is very close to the g (x, y), considering the adjusted state and output f (u, v) of the energy storage unit as the optimal working state and parameter. Constructing a power state prediction fitness function according to the content as follows:
Figure BDA0003588636990000052
in the formula, f (u, v) is a state parameter function of the flywheel energy storage unit, u represents a state, v represents a parameter, and u represents a discharging state, an energy holding state and a charging state when the value of u is-1, 0 and 1 respectively; g (x, y) is a function of frequency time; h (z, y) active load time function.
The optimal working state and parameters of the energy storage unit are found, namely the process of maximizing G (f (u, v)), and the larger G (f (u, v)), the more stable the power grid frequency after the flywheel energy storage frequency adjustment is.
d. The process of adjusting the state and the parameters f (u, v) of the energy storage unit is as follows: the initial state of the unit is f 0 (u, v), adding a disturbance quantity (delta u, delta v), and adding the state and the parameter f of the disturbed unit i+1 (u，v)＝f i (u+Δu i ，v+Δv i ) G can be obtained in the corresponding state i+1 (x, y), the index i indicates the number of iterations. Designing an optimal solution memory when the value of G (f (u, v)) is larger than a set value
Figure BDA0003588636990000063
When f is corresponding to n (u, v) are stored in a memory, and each value of G (f (u, v)) is larger than a set value
Figure BDA0003588636990000064
Comparing the lower unit state parameter with the G (f (u, v)) corresponding to the state parameter of the memory, and replacing the unit state parameter f in the memory if the lower unit state parameter is larger than the value in the memory n (u, v), then 2X 10 4 And outputting the optimal solution after secondary disturbance.
And step 3: the working state and parameters of the flywheel energy storage unit are controlled by the flywheel energy storage unit control master station, and the frequency is always kept within a certain range.
First, an automatic generation control strategy (AGC) is created that improves the conditions, specifically including:
in the control time domain, the occupation ratios of the unit in the charging state and the unit in the discharging state are lambda and mu respectively, and the expression is as follows:
Figure BDA0003588636990000061
Figure BDA0003588636990000062
in the formula, P RECN And P DISCN Respectively predicting the charging power and the discharging power of the flywheel energy storage unit by the ultra-short-term power; n is a radical of REC And N DISC The number of the charging state machine set and the number of the discharging state machine set are respectively; (k) for the corresponding value at the time instant k,
the improved AGC system model constraints are as follows:
-P BN ≤P B (k)≤P BN (6)
ηN T ≤N REC (k)≤θN T ，ηN T ≤N DISC (k)≤θN T (7)
0≤ΔN REC ≤θN T (8)
0≤ΔN DISC ≤θN T (9)
20％≤λ≤70％，20％≤μ≤70％，λ+μ≤80％ (10)
in the formula, P B The output power of the flywheel energy storage system; p BN The rated power of the energy storage system; n is a radical of T The total number of flywheel energy storage units in the system; eta and theta are respectively a specific value less than 1, and eta < theta; delta N REC The value of the change of the state of the unit in the charging state; delta N DISC The value of the change of the state of the unit in the discharge state; (k) the corresponding value at time k.
And then, controlling the flywheel storage system according to the optimal state and parameters of the flywheel storage system in the step 2 through the constraint conditions, so that the frequency is within the upper limit and the lower limit.
In the frequency adjustment link, the embodiment ignores the influence of the flywheel energy storage unit on the primary frequency modulation, that is, the unit regulation power K of the flywheel energy storage unit is not ignored G Power K per unit of regulation of the system S The influence of (c). Adjusting the power deficit Δ P of a system by means of secondary frequency modulation only S To achieve frequency stabilization. When the frequency is within the allowable range, part of the units are adjusted to the charging state according to the delta f on the premise of not influencing the frequency of the receiving-end power grid so as to ensure that a larger power shortage delta P occurs in the power grid S There is sufficient regulation capacity to maintain the grid frequency within the allowable range.
The invention also provides a frequency modulation system for flywheel energy storage of a multi-direct-current feed-in receiving-end power grid, which comprises the following components:
the data acquisition module is used for acquiring the frequency value of the receiving-end power grid and obtaining the difference value between the frequency value of the receiving-end power grid and the standard frequency through processing;
the data processing module is used for processing the input difference value, predicting the power change of the power grid in a short term by a disturbance estimation algorithm according to the difference value and outputting the optimal state and parameters of the flywheel energy storage unit;
and the unit working state adjusting module is used for adjusting the state and the parameters of the flywheel energy storage unit through an automatic power generation control strategy according to the output optimal state and the output optimal parameters, so that the frequency of the flywheel energy storage unit is kept within a set range.
The invention also provides a computer-readable storage medium, which stores a computer program, and the computer program enables a computer to execute the frequency modulation method for flywheel energy storage of the multi-direct-current feed-in receiving-end power grid.
The invention also proposes an electronic device comprising: the frequency modulation method for the flywheel energy storage of the multi-direct-current feed receiving-end power grid is realized when the processor executes the computer program.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.

Claims (10)

1. A frequency modulation method for flywheel energy storage of a multi-direct-current feed-in receiving-end power grid is characterized by comprising the following steps:
step 1: monitoring the fluctuation of the frequency value of the receiving-end power grid in real time, and acquiring the difference value between the frequency value of the receiving-end power grid and the standard frequency;
and 2, step: judging whether the difference value exceeds the limit or not, predicting power variation of the power grid in a short period by a disturbance estimation algorithm according to the difference value, and searching the optimal state and parameters of the flywheel energy storage unit;
and step 3: and adjusting the state and the parameters of the flywheel energy storage unit through an automatic power generation control strategy according to the optimal state and the parameters to keep the frequency of the flywheel energy storage unit within a set range.
2. A method as claimed in claim 1, wherein the method comprises the following steps: in step 2, when the difference value is within an upper limit and a lower limit, the flywheel energy storage unit works in an energy holding state in a short time; when the difference value is higher than the upper limit, the flywheel energy storage unit works in a charging state; when the difference value is lower, the flywheel energy storage unit works in a discharging state.
3. A method as claimed in claim 1, wherein the method comprises the following steps: in step 2, the power change of the power grid in a short term is predicted by a disturbance estimation algorithm according to the difference value, and the optimal state and parameters of the flywheel energy storage unit are searched, specifically as follows:
step 2.1: screening frequency difference values delta f acquired within a short time limit to form a 2 multiplied by N matrix, wherein each element x (i, j) (i is less than or equal to 2, j is less than or equal to N) in the matrix is regarded as a state disturbance quantity, and the numerical fluctuation among the difference values is within [0, 2 ];
step 2.2: processing a matrix formed by the frequency difference value delta f by adopting a Gauss Seidel method, taking the processed frequency difference value as an initial value, and generating an initial state by adopting an embedded Chebyshev mapping chaotic sequence;
step 2.3: designing a power state prediction fitness function for predicting power change of the power grid in a short term;
step 2.4: and (4) predicting a fitness function based on the power state, and searching the optimal working state and parameters of the energy storage unit.
4. A method as claimed in claim 3, wherein the method comprises the following steps: in step 2.3, the power state prediction fitness function is:
Figure FDA0003588636980000011
in the formula, f (u, v) is a state parameter function of the flywheel energy storage unit, u represents a state, v represents a parameter, and u represents a discharging state, an energy holding state and a charging state when the value of u is-1, 0 and 1 respectively; g (x, y) is a function of frequency time; h (z, y) is an active load time function.
5. A method as claimed in claim 4, wherein the method comprises the following steps: in step 2.4, the process of searching the optimal working state and parameters of the energy storage unit is as follows:
the initial state parameter function of the flywheel energy storage unit is f 0 (u, v) adding a disturbance amount (Δ u, Δ v), the state parameter function after disturbance addition being f i+1 (u，v)＝f i (u+Δu i ，v+Δv i ) In a corresponding state, g is obtained i+1 (x, y), the index i indicates the number of iterations; designing an optimal solution memory when the value of G (f (u, v)) is larger than a set value
Figure FDA0003588636980000023
When f is corresponding to n (u, v) are stored in a memory, the subscript n represents the nth iteration, G (f (u, v)) corresponding to the state parameter function of each unit is compared with G (f (u, v)) corresponding to the state parameter function of the memory, and if the value of G (f (u, v)) is larger than the value of the memory, the G (f (u, v)) replaces the state parameter function f (u, v)) in the memory n (u, v), then 2X 10 4 And outputting the optimal state and parameters after secondary disturbance.
6. A method as claimed in claim 2, wherein the method comprises the following steps: in step 3, the automatic power generation control strategy is specifically as follows:
in the control time domain, the occupation ratios of the unit in the charging state and the unit in the discharging state are lambda and mu respectively, and the expression is as follows:
Figure FDA0003588636980000021
Figure FDA0003588636980000022
in the formula, P RECN (k) And P DISCN (k) Respectively predicting the charging power and the discharging power of the flywheel energy storage unit at the k moment; n is a radical of hydrogen REC (k) And N DISC (k) The number of the charging state machine set and the number of the discharging state machine set at the moment k are respectively;
the constraints are as follows:
-P BN ≤P B (k)≤P BN
ηN T ≤N REC (k)≤θN T ，ηN T ≤N DISC (k)≤θN T
0≤ΔN REC ≤θN T
0≤ΔN DISC ≤θN T
20％≤λ≤70％，20％≤μ≤70％，λ+μ≤80％
in the formula, P B (k) The output power of the flywheel energy storage system at the moment k; p BN The rated power of the flywheel energy storage system; n is a radical of T The total number of the flywheel energy storage units; η and θ are values less than 1, and η < θ; delta N REC The value of the change of the state of the unit in the charging state; delta N DISC The value is the changed value of the state of the unit in the discharging state.
7. A method as claimed in claim 6, wherein the method comprises the following steps: and 3, controlling the flywheel energy storage unit through constraint conditions according to the optimal state and parameters to enable the frequency to be within the set upper and lower limit ranges.
8. A frequency modulation system of many direct currents feed in receiving end electric wire netting flywheel energy storage, its characterized in that includes:
the data acquisition module is used for acquiring the frequency value of the receiving-end power grid and obtaining the difference value between the frequency value of the receiving-end power grid and the standard frequency through processing;
the data processing module is used for processing the input difference value, predicting power variation of the power grid in a short term by a disturbance estimation algorithm according to the difference value and outputting the optimal state and parameters of the flywheel energy storage unit;
and the unit working state adjusting module is used for adjusting the state and the parameters of the flywheel energy storage unit through an automatic power generation control strategy according to the output optimal state and the output optimal parameters, so that the frequency of the flywheel energy storage unit is kept within a set range.
9. A computer-readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute a method for tuning a flywheel of a multiple dc-feed receiving grid according to any of claims 1 to 7.
10. An electronic device, comprising: a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method for frequency modulation of flywheel energy storage of a multiple direct current fed receiving grid according to any one of claims 1 to 7.
CN202210372605.8A 2022-04-11 2022-04-11 Frequency modulation method and system for flywheel energy storage of multi-direct-current feed-in receiving-end power grid Pending CN114884085A (en)

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