Method and system for primary frequency modulation of power grid using charging and discharging of lithium battery energy storage device

Abstract

The present invention discloses a method and system for primary frequency regulation of a power grid by charging and discharging a lithium battery energy storage device. The method comprises: step 1, fitting a linear P-f curve G(f) of the generator set according to two or more rated data of power P and frequency f of the generator set on the power grid source side; step 2, calculating the output power value ΔP that needs to be increased or decreased on the load side according to the frequency value f0 or frequency adjustment amount Δf required by the power grid source side dispatch using the linear P-f curve G(f); step 3, using the output power value ΔP that needs to be increased or decreased as a given power value for charging or discharging a lithium battery energy storage device connected to the grid on the source side, and tracking and regulating the given power value by controlling the charging and discharging of the lithium battery energy storage device to achieve tracking and control of the frequency f0 or frequency adjustment amount Δf dispatched on the power grid source side. The present invention uses the characteristics of the lithium battery energy storage device that can quickly and accurately respond to given requirements under automatic control to replace the traditional thermal power frequency regulation method, and provides a method for accurately regulating the power grid frequency using a lithium battery energy storage device, especially an accurate given and configuration algorithm.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery energy storage, and in particular to a method and system for primary frequency modulation of a power grid by charging and discharging a lithium battery energy storage device. Background Art

[0002] In recent years, due to the large number of intermittent new energy sources such as photovoltaic power and wind power connected to the power grid in my country, the frequency and load of the power grid have fluctuated, resulting in a decrease in the safety of the power grid. Therefore, it is necessary to adjust the frequency and load of the power grid in a timely manner. At present, the frequency regulation method of my country's power grid is mainly to respond to the frequency regulation instructions of the power grid dispatch by adjusting the active output of thermal power generating units.

[0003] Due to the slow start-up, long response lag and low ramp rate of the generator sets of the existing thermal power generation technology, the frequency regulation instructions for tracking the grid dispatch have problems such as regulation delay, large regulation deviation and easy regulation reversal; moreover, the frequent power conversion of thermal power units will increase the wear and fatigue of the unit equipment, increase energy consumption and shorten the life of the unit. Therefore, new frequency regulation technologies and means are urgently needed to meet the frequency regulation needs of the grid. Lithium battery energy storage devices have the advantages of fast response speed, strong short-term power throughput capacity and flexible regulation, and can achieve precise control at any power point within the rated power. However, there is currently no method to use lithium battery energy storage devices to achieve primary frequency regulation of the grid.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for primary frequency modulation of a power grid by charging and discharging a lithium battery energy storage device, which can utilize the charging and discharging of a lithium battery energy storage device as a frequency modulation power source to perform primary frequency modulation on the source side of the power grid, thereby improving the power quality, stability and safety of the power grid, while reducing harmful gas and carbon emissions, thereby solving the above-mentioned technical problems existing in the prior art.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A method for primary frequency modulation of a power grid by charging and discharging a lithium battery energy storage device, comprising:

[0008] Step 1, fitting a linear Pf curve G(f) of the generator set according to two or more rated data of power P and frequency f of the generator set at the source side of the power grid;

[0009] Step 2, according to the frequency value f0 or frequency adjustment amount Δf required by the grid source side dispatch, use the linear Pf curve G(f) to calculate the output power value ΔP that needs to be increased or decreased on the load side;

[0010] Step 3, using the output power value ΔP that needs to be increased or decreased as the given power value for charging or discharging the lithium battery energy storage device connected to the grid on the source side, and tracking and adjusting the given power value by controlling the charging and discharging of the lithium battery energy storage device to achieve tracking and control of the frequency f0 or the frequency adjustment amount Δf scheduled on the source side of the power grid.

[0011] A primary frequency modulation system for a power grid using a lithium battery energy storage device for charging and discharging, comprising:

[0012] Lithium battery energy storage device and charge and discharge frequency modulation control device; wherein,

[0013] The lithium battery energy storage device has a main charging and discharging circuit connected to the medium-voltage busbar of the generator set on the power grid source side;

[0014] The charge-discharge frequency modulation control device is respectively connected to the control end of the power generator set on the power grid source side and the lithium battery energy storage device, and can fit the linear Pf curve G(f) of the power generator set according to two or more rated data of the power P and frequency f of the power generator set on the source side, and calculate the output power value ΔP that needs to be increased or decreased on the load side according to the frequency value f0 or frequency adjustment amount Δf required by the power grid dispatching by using the linear Pf curve G(f), and use the output power value ΔP that needs to be increased or decreased as the given power value for charging or discharging the lithium battery energy storage device connected to the power grid source side, and track and adjust the given power value by controlling the charging and discharging of the lithium battery energy storage device to achieve tracking and control of the frequency f0 or frequency adjustment amount Δf of the power grid dispatching.

[0015] Compared with the prior art, the method and system for primary frequency modulation of a power grid by charging and discharging a lithium battery energy storage device provided by the present invention has the following beneficial effects:

[0016] By utilizing the flexible charging and discharging characteristics of lithium battery energy storage devices, its main charging and discharging circuit is connected to the medium-voltage busbar of the generator set on the source side of the power grid. By adjusting and tracking the output power value ΔP that needs to be increased or decreased on the load side determined by the fitted linear Pf curve G(f) of the generator set on the source side, the primary frequency modulation of the power grid source side is achieved. This frequency modulation method is simple and flexible. It can improve the power quality, stability and safety of the power grid while effectively reducing harmful gases and carbon emissions. It solves the problem that intermittent new energy sources such as photovoltaics and wind power are connected to the power grid, which causes fluctuations in the frequency and load of the power grid and leads to a decrease in the safety of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for primary frequency modulation of a power grid using charging and discharging of a lithium battery energy storage device provided in an embodiment of the present invention.

[0019] Figure 2 A schematic diagram of a method for primary frequency modulation of a power grid by charging and discharging a lithium battery energy storage device provided in an embodiment of the present invention.

[0020] Figure 3 A schematic diagram of calculation of a method for primary frequency modulation of a power grid by charging and discharging a lithium battery energy storage device provided in an embodiment of the present invention.

[0021] Figure 4 A schematic diagram of a primary frequency modulation system for a power grid using a lithium battery energy storage device for charging and discharging provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the specific content of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0023] First, the terms that may be used in this article are explained as follows:

[0024] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0025] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0026] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0027] Unless otherwise specified or limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this article can be understood according to specific circumstances.

[0028] The orientation or position relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or position relationship shown in the drawings and are only for the convenience and simplification of description, and do not explicitly or implicitly indicate that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation of this document.

[0029] The scheme provided by the present invention is described in detail below. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professionals in the field. If the specific conditions are not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturers are not specified in the reagents or instruments used in the embodiments of the present invention, they are all conventional products that can be purchased commercially.

[0030] like Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a method for frequency modulation on the power grid source side by charging and discharging a lithium battery energy storage device, comprising:

[0031] Step 1, fitting a linear Pf curve G(f) of the generator set according to two or more rated data of power P and frequency f of the generator set at the source side of the power grid;

[0032] Step 2, according to the frequency value f0 or frequency adjustment amount Δf required by the grid source side dispatch, use the linear Pf curve G(f) to calculate the output power value ΔP that needs to be increased or decreased on the load side;

[0033] Step 3, using the output power value ΔP that needs to be increased or decreased as the given power value for charging or discharging the lithium battery energy storage device connected to the grid on the source side, and tracking and adjusting the given power value by controlling the charging and discharging of the lithium battery energy storage device to achieve tracking and control of the frequency f0 or the frequency adjustment amount Δf scheduled on the source side of the power grid.

[0034] See also Figure 3 Preferably, in step 3 of the above method, the charging and discharging of the lithium battery energy storage device is controlled in the following manner to track and adjust the given power value in the following manner, including:

[0035] When there is no frequency modulation instruction, the lithium battery energy storage device is controlled to automatically charge or discharge to 50% SOC standby, and the rated capacity adjustment range of the lithium battery energy storage device is ±40% SOC;

[0036] When the output power value ΔP that needs to be increased or decreased as the given power value is a positive real number, controlling the lithium battery energy storage device to discharge at the output power value ΔP;

[0037] When the output power value ΔP that needs to be increased or decreased as the given power value is a negative real number, the lithium battery energy storage device is controlled to be charged with the output power value ΔP.

[0038] Preferably, in the above method, the frequency modulation power ΔPx of the lithium battery energy storage device is calculated and determined according to the following formula:

[0039]

[0040] Among them, f0 is the rated frequency of the generator set and the grid load, in Hz; fx is the target frequency of the grid dispatch, in Hz; Kx is the adjustment rate of the grid load, which is set to 2%; P0 is the rated power of the generator set, in MW; P1 is the power corresponding to f1 of the known generator set, in MW; f1 is the non-rated frequency of the known generator set, in Hz;

[0041] When the frequency modulation time is 1h and the charging and discharging capacity of the lithium battery is 1C, the capacity of the lithium battery energy storage device is: 2.5ΔPx, unit MWh.

[0042] See also Figure 4 The embodiment of the present invention also provides a primary frequency modulation system for a power grid using a lithium battery energy storage device for charging and discharging, comprising:

[0043] Lithium battery energy storage device and charge and discharge frequency modulation control device; wherein,

[0044] The lithium battery energy storage device has a main charging and discharging circuit connected to the medium-voltage busbar of the generator set on the power grid source side;

[0045] The charge-discharge frequency modulation control device is respectively connected to the control end of the power generator set on the power grid source side and the lithium battery energy storage device, and can fit the linear Pf curve G(f) of the power generator set according to two or more rated data of the power P and frequency f of the power generator set on the source side, and calculate the output power value ΔP that needs to be increased or decreased on the load side according to the frequency value f0 or frequency adjustment amount Δf required by the power grid dispatching by using the linear Pf curve G(f), and use the output power value ΔP that needs to be increased or decreased as the given power value for charging or discharging the lithium battery energy storage device connected to the power grid source side, and control the charging and discharging of the lithium battery energy storage device to track and adjust the given power value to achieve tracking and control of the frequency f0 or frequency adjustment amount Δf of the power grid dispatching.

[0046] Preferably, in the above system, the charge and discharge frequency modulation control device controls the charge and discharge of the lithium battery energy storage device to track and adjust the given power value in the following manner, including:

[0047] When there is no frequency modulation instruction, the lithium battery energy storage device is controlled to automatically charge or discharge to 50% SOC standby, and the rated capacity adjustment range of the lithium battery energy storage device is ±40% SOC;

[0048] When the output power value ΔP that needs to be increased or decreased as the given power value is a positive real number, controlling the lithium battery energy storage device to discharge at the output power value ΔP;

[0049] When the output power value ΔP that needs to be increased or decreased as the given power value is a negative real number, the lithium battery energy storage device is controlled to be charged with the output power value ΔP.

[0050] Preferably, in the above system, the frequency modulation power ΔPx of the lithium battery energy storage device is calculated and determined according to the following formula:

[0051]

[0052] Among them, f0 is the rated frequency of the generator set and the grid load, in Hz; fx is the target frequency of the grid dispatch, in Hz; Kx is the adjustment rate of the grid load, which is set to 2%; P0 is the rated power of the generator set, in MW; P1 is the power corresponding to f1 of the known generator set, in MW; f1 is the non-rated frequency of the known generator set, in Hz;

[0053] When the frequency modulation time is 1h and the charging and discharging capacity of the lithium battery is 1C, the capacity of the lithium battery energy storage device is: 2.5ΔPx, unit MWh.

[0054] The above-mentioned lithium battery energy storage device is commonly used on the market and can be flexibly connected to public power grids of various voltage levels such as 0.4kV, 6kV, 10kV, 18kV, 20kV, 35kV, etc. It is a complete set of lithium battery energy storage equipment that can accept network control signals and perform fully automatic constant power charging, discharging, fault alarm and other unmanned operations.

[0055] In summary, the system and method of the embodiments of the present invention make full use of the characteristic of the lithium battery energy storage device that is easy to control charging and discharging, and use the control of its charging and discharging regulation and tracking of the output power value ΔP that needs to be increased or decreased on the load side, thereby achieving tracking and control of the dispatched frequency f0 or frequency adjustment amount Δf on the power grid source side.

[0056] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the solution provided by the embodiment of the present invention is described in detail with specific embodiments below.

[0057] Example 1

[0058] like Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a method for frequency modulation on the power grid source side by charging and discharging a lithium battery energy storage device, comprising the following steps:

[0059] Step 1, fitting a linear Pf curve G(f) of the generator set according to two or more rated data of power P and frequency f of the generator set at the source side of the power grid;

[0060] Step 2, according to the frequency value f0 required by the grid dispatch or the frequency adjustment amount Δf required by the grid dispatch, use the G(f) curve to calculate the output power value ΔP that needs to be increased or decreased on the load side;

[0061] Step 3, the output power value ΔP that needs to be increased or decreased is used as the given power value for charging or discharging the lithium battery energy storage device connected to the grid source side, and the given power value is tracked and adjusted by controlling the charging and discharging of the lithium battery energy storage device, so as to achieve fast and accurate tracking of the frequency f0 by the grid.

[0062] In step 3 of the above method, the charging and discharging of the lithium battery energy storage device is controlled in the following manner to track and adjust the given power value, including:

[0063] When there is no frequency modulation command, the lithium battery energy storage device is controlled to automatically charge or discharge to 50% SOC standby, and the rated capacity adjustment range of the lithium battery energy storage device is ±40% SOC;

[0064] When the given power value ΔP is a positive real number, the lithium battery energy storage device is controlled to discharge at the given power value ΔP;

[0065] When the given power value ΔP is a negative real number, the lithium battery energy storage device is controlled to charge with the given power value ΔP;

[0066] In this way, the tracking and control of the frequency f0 or the frequency adjustment amount Δf of the power grid dispatching is achieved.

[0067] The following is an explanation of how to fit the linear Pf curve G(f) of the generator set in step 1. The power grid system includes the following states, see Figure 2 , Figure 3 :

[0068] 1) Initial state: The power grid system operates at the intersection a of the load PF characteristic curve L1(f) and the generator set PF characteristic curve G(f), and the frequency is determined to be f0;

[0069] 2) The load power increases by ΔP1, the load PF characteristic curve changes to L2(f), the generator set performs a frequency modulation, outputs power ΔPg, L2(f) and G(f) intersect at point c, and the frequency f1 is determined;

[0070] 3) At this time, the frequency deviation is Δf, and the frequency modulation is completed;

[0071] 4) If the grid dispatching instruction is to restore f0, that is, to adjust the frequency Δf, the lithium battery energy storage device discharges to the grid, and the discharge power is ΔP1, which is equivalent to the load returning from L2(f) to L1(f), intersecting G(f) at point a, and the frequency is restored to f0 and maintained;

[0072] 5) On the contrary, the process is the opposite of the above, and the lithium battery energy storage device is charged from the grid to restore the frequency f0 until the dispatch instruction is released;

[0073] 6) Figure 3 The calculation diagram of the primary frequency modulation method of the present invention is given. Given two points (P0, f0) and (P1, f1) on the characteristic curve G(f) of the generator set, the load frequency adjustment rate, i.e., the slope of the L1(f), L2(f), L(x) curves K1=K2=Kx=2%=0.02, the target frequency fx(Hz) of the power grid dispatching frequency modulation can be obtained. Figure 4 The schematic lithium battery energy storage device is connected to the grid as a primary frequency modulation power source. The calculation process of the output or input power of the lithium battery energy storage device is as follows:

[0074]

[0075] In the above formula, Kg is the adjustment rate of the generator set, which is also the slope of the generator Pf characteristic curve; f0 is the rated frequency of the generator set and the grid load, in Hz; f1 is the known non-rated frequency of the generator set, in Hz; P0 is the rated power of the generator set, in MW; P1 is the power corresponding to the known generator set and f1, in MW; fx is the target frequency of the grid dispatch, in Hz; P3 is the intermediate power value used for calculation, in MW; Px is the power value corresponding to the grid load Lx and f0, in MW; Kx is the adjustment rate of the grid load, which is set to 2%;

[0076] From formula (1), P3 is:

[0077]

[0078] Substituting equation (3) into equation (2) above, we can obtain Px:

[0079]

[0080] From formula (4), we can know that when the lithium battery energy storage device replaces the generator set to respond to the grid dispatch and adjust the frequency to fx, the power ΔPx that needs to be discharged or charged is:

[0081]

[0082] In formula (5), ΔPx is the charging or discharging power of the lithium battery energy storage device during frequency modulation, MW; when ΔPx is a positive value, it means that the lithium battery energy storage device discharges to the grid; when ΔPx is a negative value, it means that the lithium battery energy storage device is charged from the grid.

[0083] Since the frequency modulation rated capacity adjustment range of the lithium battery energy storage device is limited to ±40% SOC in the present invention, when the rated frequency modulation power is ΔPx, the frequency modulation time is 1h, and the lithium battery charge and discharge capacity is 1C, the lithium battery rated capacity should be configured to 2.5ΔPx (MWh).

[0084] The present invention utilizes the functions and performance of lithium battery energy storage devices to replace the primary frequency modulation of traditional generator sets. According to the "T / CEC Electrochemical Energy Storage Power Station Frequency Modulation and Peak Modulation Technical Specifications", the primary frequency modulation difference rate should not be greater than 3%, preferably 2%, and the present invention adopts 2%. The present invention has the following characteristics as a primary frequency modulation power supply for the power grid:

[0085] (1) The lithium battery energy storage frequency modulation system has a fast response speed and strong short-term power throughput capacity: the power rises from 0 to 90% of the rated value, or converts from the charging rated power to 90% of the discharging rated power in less than 100 milliseconds.

[0086] (2) Accurate control at any power point: no dead zone, control accuracy 5% between 20% and rated power.

[0087] (3) It can independently participate in the frequency regulation service of the power grid as a frequency regulation power source, solve the problem of power grid frequency deviation, and improve the power quality and system stability of the power grid.

[0088] (4) The power factor is above 0.98 and can be adjusted in four quadrants between -1 and 1.

[0089] Example 2

[0090] like Figure 4 As shown, the embodiment of the present invention also provides a primary frequency modulation system for the power grid using the charging and discharging of a lithium battery energy storage device. The lithium battery energy storage device is connected to the power grid as a primary frequency modulation power source, and the main circuit of the lithium battery energy storage device is connected to the medium voltage bus of the power grid. At the same time, the network control interface of the lithium battery energy storage device is connected to the dispatching network of the power grid, so that the frequency of the power grid can be adjusted. The charging and discharging frequency modulation control device that controls the charging and discharging of the lithium battery energy storage device is connected to the dispatching network of the power grid. Examples are as follows:

[0091] The basic parameters of a power plant are as follows:

[0092] project quantity unit Generator set rated power 255 MW Rated frequency of power generation 50 Hz When the power generation frequency changes by 0.1Hz, the corresponding power change value 7.495 MW Frequency adjustment range 0.04 Hz

[0093] Through the basic parameters in the table above and Figure 3 The corresponding diagram of primary frequency modulation calculation shows that:

[0094] P0 = 255 (MW);

[0095] f0=50(Hz);

[0096] P1=255+7.495=262.495(MW);

[0097] f1=50-0.1=49.9(Hz);

[0098] fx=50-0.04=49.96(Hz);

[0099] Substitute the above known quantities and Kx=0.02 into equation (5) of Example 1 to calculate the frequency modulation power and capacity configuration of the lithium battery energy storage device:

[0100]

[0101] It is concluded that the frequency modulation power of this power plant is 4.998MW. When the frequency modulation time is 1h and the lithium battery charge and discharge capacity is 1C, the configuration of the lithium battery rated capacity should be 2.5ⅹ4.998=12.495(MWh);

[0102] In summary, the configuration of this power plant using lithium battery energy storage device for frequency regulation is:

[0103] Rated capacity of lithium battery: not less than 12.495MWh;

[0104] Lithium battery charge and discharge characteristics: 1C;

[0105] Lithium battery frequency modulation device charging and discharging rated power: 4.998MW;

[0106] The maximum duration of a single lithium battery frequency modulation is 1h.

[0107] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0108] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for primary frequency modulation of a power grid by charging and discharging a lithium battery energy storage device, characterized in that: include: Step 1, fitting a linear Pf curve G(f) of the generator set according to two or more rated data of power P and frequency f of the generator set at the source side of the power grid; Step 2, according to the frequency value f0 or frequency adjustment amount Δf required by the grid source side dispatch, use the linear Pf curve G(f) to calculate the output power value ΔP that needs to be increased or decreased on the load side; Step 3, using the output power value ΔP that needs to be increased or decreased as a given power value for charging or discharging the lithium battery energy storage device connected to the grid on the source side, and tracking and adjusting the given power value by controlling the charging and discharging of the lithium battery energy storage device to achieve tracking and control of the frequency f0 or frequency adjustment amount Δf dispatched on the grid source side; In step 3, the charging and discharging of the lithium battery energy storage device is controlled in the following manner to track and adjust the given power value in the following manner, including: When there is no frequency modulation instruction, the lithium battery energy storage device is controlled to automatically charge or discharge to 50% SOC standby, and the rated capacity adjustment range of the lithium battery energy storage device is ±40% SOC; When the output power value ΔP that needs to be increased or decreased as the given power value is a positive real number, controlling the lithium battery energy storage device to discharge at the output power value ΔP; When the output power value ΔP value that needs to be increased or decreased as the given power value is a negative real number, controlling the lithium battery energy storage device to charge with the output power value ΔP; The lithium battery energy storage device replaces the generator set to respond to the grid dispatch and adjust the frequency to fx. The power ΔPx required to be discharged or charged is calculated and determined according to the following formula: Among them, f0 is the rated frequency of the generator set and the grid load, in Hz; fx is the target frequency of the grid dispatch, in Hz; Kx is the adjustment rate of the grid load, which is set to 2%; P0 is the rated power of the generator set, in MW; P1 is the power corresponding to f1 of the known generator set, in MW; f1 is the non-rated frequency of the known generator set, in Hz; When the frequency modulation time is 1h and the charging and discharging capacity of the lithium battery is 1C, the capacity of the lithium battery energy storage device is: 2.5ΔPx, unit MWh.

2. A primary frequency modulation system for a power grid using a lithium battery energy storage device for charging and discharging, characterized in that: The method for implementing claim 1 comprises: Lithium battery energy storage device and charge and discharge frequency modulation control device; among which, The lithium battery energy storage device has a main charging and discharging circuit connected to the medium-voltage busbar of the generator set on the power grid source side; The charge-discharge frequency modulation control device is respectively connected to the control end of the power generator set on the power grid source side and the lithium battery energy storage device, and can fit the linear Pf curve G(f) of the power generator set according to two or more rated data of the power P and frequency f of the power generator set on the source side, and calculate the output power value ΔP that needs to be increased or decreased on the load side according to the frequency value f0 or frequency adjustment amount Δf required by the power grid dispatching by using the linear Pf curve G(f), and use the output power value ΔP that needs to be increased or decreased as the given power value for charging or discharging the lithium battery energy storage device connected to the power grid source side, and track and adjust the given power value by controlling the charging and discharging of the lithium battery energy storage device to achieve tracking and control of the frequency f0 or frequency adjustment amount Δf of the power grid dispatching.

3. The primary frequency modulation system for power grid using lithium battery energy storage device charging and discharging according to claim 2 is characterized in that: The charge and discharge frequency modulation control device controls the charge and discharge of the lithium battery energy storage device to track and adjust the given power value in the following manner, including: When there is no frequency modulation instruction, the lithium battery energy storage device is controlled to automatically charge or discharge to 50% SOC standby, and the rated capacity adjustment range of the lithium battery energy storage device is ±40% SOC; When the output power value ΔP that needs to be increased or decreased as the given power value is a positive real number, controlling the lithium battery energy storage device to discharge at the output power value ΔP; When the output power value ΔP that needs to be increased or decreased as the given power value is a negative real number, the lithium battery energy storage device is controlled to be charged with the output power value ΔP.

4. The primary frequency modulation system for power grid using lithium battery energy storage device charging and discharging according to claim 2 or 3, characterized in that: The frequency modulation power ΔPx of the lithium battery energy storage device is calculated and determined according to the following formula: Among them, f0 is the rated frequency of the generator set and the grid load, in Hz; fx is the target frequency of the grid dispatch, in Hz; Kx is the adjustment rate of the grid load, which is set to 2%; P0 is the rated power of the generator set, in MW; P1 is the power corresponding to f1 of the known generator set, in MW; f1 is the non-rated frequency of the known generator set, in Hz; When the frequency modulation time is 1h and the charging and discharging capacity of the lithium battery is 1C, the capacity of the lithium battery energy storage device is: 2.5ΔPx, unit MWh.

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