Energy storage system and operating method thereof

Abstract

The invention provides an energy storage system and an operating method thereof, and the energy storage system is used for being coupled to a power grid so as to provide power regulation of which the maximum value is an appointed capacity for the power grid. The energy storage system comprises an energy storage unit, a measuring unit and a control unit. The measuring unit is used for measuring operation frequency of the power grid. The control unit is coupled to the measuring unit and the energy storage unit and is used for receiving the operation frequency of the power grid measured by the measuring unit. When the operation frequency of the power grid measured by the measuring unit is greater than or equal to a first frequency boundary value and less than or equal to a second frequency boundary value, the control unit sets the adjustment proportion of power adjustment as a first operation proportion which is less than or equal to 0 and greater than or equal to a first input boundary value. The first frequency boundary value is smaller than the first frequency and / or the second frequency boundary value is larger than the second frequency.

Description

Technical Field

[0001] This case involves an energy storage system and its operation method, especially an energy storage system and its operation method that can improve efficiency. Background Art

[0002] In response to the increasing demand for energy and environmental protection, renewable energy such as wind power and solar energy plays an increasingly important role in the power system and continuously increases the proportion of power supply. However, the unstable characteristics of renewable energy also bring many management challenges to the traditional power grid, and energy storage systems that can increase reliability, resilience, and flexibility are increasingly being applied to the power grid. The energy storage system can include a battery system (such as power conversion devices such as fuel cells and lithium batteries) and an energy management system, and can provide functions such as voltage regulation and frequency regulation.

[0003] In response to the instability of renewable energy and the changes in the power generation structure and power consumption demand of the power system, power operators have developed a series of auxiliary service products and formulated corresponding power market rules to enhance the stability and resilience of the power grid, such as frequency modulation services, voltage regulation services, demand response, black start, etc. The above services all have specific rules to regulate the response of the energy storage. However, directly regulating the energy storage according to the rules may lead to poor system performance, and during operation, the energy storage system may operate in a state of poor efficiency or over-consume the energy storage system and reduce its service life due to factors such as the energy storage system configuration, power topology, the surrounding environment of the energy storage (such as temperature and humidity), and the power grid situation. Therefore, how to integrate the energy storage system in multiple aspects and operate at the optimal working point so that the energy storage system can effectively utilize the site structure, improve or regulate the energy storage efficiency curve, and extend the battery life is an urgent need at present. Summary of the Invention

[0004] The purpose of this case is to provide an energy storage system and its operation method to solve the aforementioned technical problems.

[0005] To achieve the above object, the present case provides an energy storage system for coupling to a power grid to provide power regulation with a maximum value equal to the agreed capacity to the power grid. When the operating frequency of the power grid is greater than or equal to the first frequency and less than or equal to the second frequency, the regulation ratio of the power regulation of the energy storage system is greater than or equal to the first input boundary value and less than or equal to the first output boundary value. When the operating frequency of the power grid is greater than or equal to the third frequency and less than or equal to the first frequency, the regulation ratio of the power regulation of the energy storage system is greater than or equal to the first input boundary value and less than or equal to the second output boundary value. When the operating frequency decreases from the first frequency to the third frequency, a plurality of first upper limit values of the regulation ratio corresponding to the change in the operating frequency increase from the first output boundary value to the second output boundary value correspondingly, and a plurality of first lower limit values of the regulation ratio corresponding to the change in the operating frequency increase from the first input boundary value to the second output boundary value correspondingly. When the operating frequency of the power grid is greater than or equal to the second frequency and less than or equal to the fourth frequency, the regulation ratio of the power regulation of the energy storage system is greater than or equal to the second input boundary value and less than or equal to the first output boundary value. When the operating frequency increases from the second frequency to the fourth frequency, a plurality of second upper limit values of the regulation ratio corresponding to the change in the operating frequency decrease from the first output boundary value to the second input boundary value correspondingly, and a plurality of second lower limit values of the regulation ratio corresponding to the change in the operating frequency decrease from the first input boundary value to the second input boundary value correspondingly. The energy storage system includes an energy storage unit, a measurement unit, and a control unit. The energy storage unit is used to store and provide electrical energy. The measurement unit is used to measure the operating frequency of the power grid. The control unit is used to couple to the measurement unit and the energy storage unit and is used to receive the operating frequency of the power grid measured by the measurement unit. When the state of charge of the energy storage unit is greater than the first electric quantity, the energy storage unit is in a normal electric quantity state; when the state of charge of the energy storage unit is less than the first electric quantity, the energy storage unit is in a low electric quantity state. When the control unit sets the regulation ratio of the power regulation of the energy storage system to be greater than 0, the control unit sets the energy storage unit to supply power to the power grid at the regulation ratio of the agreed capacity; when the control unit sets the regulation ratio of the power regulation of the energy storage system to be less than 0, the control unit sets the energy storage unit to charge from the power grid at the regulation ratio of the agreed capacity. When the operating frequency of the power grid measured by the measurement unit is greater than or equal to the first frequency boundary value and less than or equal to the second frequency boundary value, the control unit sets the regulation ratio of the power regulation to the first operation ratio, and the first operation ratio is less than or equal to 0 and greater than or equal to the first input boundary value. The first frequency boundary value is less than the first frequency and / or the second frequency boundary value is greater than the second frequency.

[0006] To achieve the above object, the present case further provides an operating method for an energy storage system, where the energy storage system is used to be coupled to a power grid to provide power regulation with a maximum value of the agreed capacity to the power grid. When the operating frequency of the power grid is greater than or equal to the first frequency and less than or equal to the second frequency, the regulation ratio of the power regulation of the energy storage system is greater than or equal to the first input boundary value and less than or equal to the first output boundary value. When the operating frequency of the power grid is greater than or equal to the third frequency and less than or equal to the first frequency, the regulation ratio of the power regulation of the energy storage system is greater than or equal to the first input boundary value and less than or equal to the second output boundary value. When the operating frequency decreases from the first frequency to the third frequency, a plurality of first upper limit values of the regulation ratio corresponding to the change in the operating frequency increase from the first output boundary value to the second output boundary value correspondingly, and a plurality of first lower limit values of the regulation ratio corresponding to the change in the operating frequency increase from the first input boundary value to the second output boundary value correspondingly. When the operating frequency of the power grid is greater than or equal to the second frequency and less than or equal to the fourth frequency, the regulation ratio of the power regulation of the energy storage system is greater than or equal to the second input boundary value and less than or equal to the first output boundary value. When the operating frequency increases from the second frequency to the fourth frequency, a plurality of second upper limit values of the regulation ratio corresponding to the change in the operating frequency decrease from the first output boundary value to the second input boundary value correspondingly, and a plurality of second lower limit values of the regulation ratio corresponding to the change in the operating frequency decrease from the first input boundary value to the second input boundary value correspondingly. The energy storage system includes an energy storage unit, a measurement unit, and a control unit. The energy storage unit is used to store and provide electric energy. The measurement unit is used to measure the operating frequency of the power grid. The control unit is used to be coupled to the measurement unit and the energy storage unit and is used to receive the operating frequency of the power grid measured by the measurement unit. When the state of charge of the energy storage unit is greater than the first electric quantity, the energy storage unit is in a normal electric quantity state; when the state of charge of the energy storage unit is less than the first electric quantity, the energy storage unit is in a low electric quantity state. When the control unit sets the regulation ratio of the power regulation of the energy storage system to be greater than 0, the control unit sets the energy storage unit to supply power to the power grid at the regulation ratio of the agreed capacity; when the control unit sets the regulation ratio of the power regulation of the energy storage system to be less than 0, the control unit sets the energy storage unit to charge from the power grid at the regulation ratio of the agreed capacity. The operating method includes: when the operating frequency of the power grid measured by the measurement unit is greater than or equal to the first frequency boundary value and less than or equal to the second frequency boundary value, setting the control unit to set the regulation ratio of the power regulation to the first operation ratio, where the first operation ratio is less than or equal to 0 and greater than or equal to the first input boundary value, the first frequency boundary value is less than the first frequency and / or the second frequency boundary value is greater than the second frequency.

[0007] The foregoing embodiments can improve the efficiency of the energy storage system, and can optimize the battery of the energy storage system to achieve an optimized battery life, achieving excellent electric energy and reducing electric energy loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1Schematic diagram of the architecture of an embodiment of the energy storage system in this case;

[0009] Figure 2 Illustrative Figure 1 An embodiment of the energy storage unit;

[0010] Figure 3 Schematic diagram of the reference relationship between the adjustment ratio of the power regulation provided by the energy storage system and the operating frequency of the power grid;

[0011] Figure 4A Schematic diagram of an embodiment of the adjustment ratio of the power regulation provided by the energy storage system corresponding to the operating frequency of the power grid when the energy storage unit is in a normal power state;

[0012] Figure 4B Schematic diagram of an embodiment of the efficiency of the energy storage system and the adjustment ratio of the power regulation provided by it when the energy storage unit is in a normal power state;

[0013] Figure 4C Schematic diagram of another embodiment of the efficiency of the energy storage system and the adjustment ratio of the power regulation provided by it when the energy storage unit is in a normal power state;

[0014] Figure 5A Schematic diagram of another embodiment of the adjustment ratio of the power regulation provided by the energy storage system corresponding to the operating frequency of the power grid when the energy storage unit is in a normal power state;

[0015] Figure 5B Schematic diagram of another embodiment of the efficiency of the energy storage system and the adjustment ratio of the power regulation provided by it when the energy storage unit is in a normal power state;

[0016] Figure 6A Schematic diagram of yet another embodiment of the adjustment ratio of the power regulation provided by the energy storage system corresponding to the operating frequency of the power grid when the energy storage unit is in a normal power state;

[0017] Figure 6B Schematic diagram of yet another embodiment of the efficiency of the energy storage system and the adjustment ratio of the power regulation provided by it when the energy storage unit is in a normal power state;

[0018] Figure 7A Schematic diagram of an embodiment of the adjustment ratio of the power regulation provided by the energy storage system corresponding to the operating frequency of the power grid when the energy storage unit is in a low power state;

[0019] Figure 7B Schematic diagram of an embodiment of the efficiency of the energy storage system and the adjustment ratio of the power regulation provided by it when the energy storage unit is in a low power state;

[0020] Figure 8Schematic diagram of another embodiment of the regulation ratio of power regulation provided by an energy storage system corresponding to the operating frequency of a power grid when the energy storage unit is in a low power state;

[0021] Figure 9A Schematic diagram of an embodiment of the regulation ratio of power regulation provided by an energy storage system corresponding to the operating frequency of a power grid when the energy storage unit is in a high power state;

[0022] Figure 9B Schematic diagram of an embodiment of the efficiency of an energy storage system and the regulation ratio of the power regulation provided by it when the energy storage unit is in a high power state;

[0023] Figure 10 Schematic diagram of another embodiment of the regulation ratio of power regulation provided by an energy storage system corresponding to the operating frequency of a power grid when the energy storage unit is in a high power state.

[0024] Description of the reference numerals in the drawings

[0025] 1: Energy storage system

[0026] 2: Point of common coupling

[0027] 3: Power grid

[0028] 11: Energy storage unit

[0029] 11_1, 11_2, 11_n: Energy storage devices

[0030] 12: Measuring unit

[0031] 13: Control unit

[0032] 14: Auxiliary power supply device

[0033] 111: Battery module

[0034] 112: Power regulator

[0035] 113: Transformer

[0036] fr1: First frequency

[0037] fr2: Second frequency

[0038] fr3: Third frequency

[0039] fr4: Fourth frequency

[0040] fr5: Fifth frequency

[0041] fr6: Sixth frequency

[0042] IL1: First input boundary value

[0043] IL2: Second input boundary value

[0044] IL3: Third input boundary value

[0045] OL1: First output boundary value

[0046] OL2: Second output boundary value

[0047] OL3: Third output boundary value

[0048] f11, f21, f31: First frequency boundary value

[0049] f12, f22, f32: Second frequency boundary value

[0050] f13, f23, f33: Third frequency boundary value

[0051] f14, f14a, f24, f34: Fourth frequency boundary value

[0052] f15, f25, f35: Fifth frequency boundary value

[0053] f16, f26, f36: Sixth frequency boundary value

[0054] f17, f17a: Seventh frequency boundary value

[0055] f18: Eighth frequency boundary value

[0056] R11, R21, R31: First operation ratio

[0057] R12, R22, R32: Second operation ratio

[0058] R13, R23, R33: Third operation ratio

[0059] R14, R24, R34: Fourth operation ratio

[0060] R15: Fifth operation ratio

[0061] 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1Ba, 1Ia: Operating points

[0062] 2A, 2B, 2Ca, 2Cb, 2D, 2E, 2F, 2G, 2H: Operating points

[0063] 3A, 3B, 3C, 3D, 3E, 3Fa, 3Fb, 3G, 3H: Operating points

[0064] f0: Default supply frequency

[0065] fx: First critical frequency

[0066] fy: Second critical frequency

[0067] TH1: First efficiency threshold

[0068] TH2: Second efficiency threshold

[0069] TH3: Third efficiency threshold

[0070] TH4: Fourth efficiency threshold

[0071] TH5: Fifth efficiency threshold

[0072] TH6: Sixth efficiency threshold Detailed implementation manners

[0073] Some typical embodiments embodying the features and advantages of the present case will be described in detail in the following description. It should be understood that the present case can have various variations in different embodiments, all of which do not depart from the scope of the present case.

[0074] Figure 1 It is a schematic structural diagram of an embodiment of the energy storage system of the present case. As Figure 1 shown, the energy storage system 1 is coupled to the power grid 3 through the grid connection point 2 to provide power regulation for the power grid 3, where the maximum value of the power regulation provided by the energy storage system 1 is a specified capacity. For example, the specified capacity of the energy storage system 1 can be set to the awarded capacity (volume accepted) agreed with the power operator. In this embodiment, the energy storage system 1 includes an energy storage unit 11, a measurement unit 12, a control unit 13, and an auxiliary power supply device 14, where the energy storage unit 11, the measurement unit 12, and the auxiliary power supply device 14 are respectively coupled to the grid connection point 2, and the control unit 13 is coupled to the energy storage unit 11 and the measurement unit 12. For the sake of simplicity of the drawing and convenience of description, Figure 1 other components of the energy storage system 1 are not shown in the figure. In this embodiment, the energy storage system 1 is divided into an energy storage unit 11, a measurement unit 12, a control unit 13, and an auxiliary power supply device 14 to clearly illustrate the operation mode of the energy storage system 1. Each component of the energy storage system 1 can be set to an appropriate number respectively, for example, one or more auxiliary power supply devices. In addition, the above units can be implemented by appropriate components respectively, or can be integrated or implemented by one or more components respectively. For example, the measurement unit 12 and the control unit 13 can perform their functions by the same circuit composed of discrete components and / or integrated circuit components.

[0075] The measurement unit 12 can adopt an ammeter or other suitable measurement devices, and can measure the electrical parameters at the grid connection point 2 or other suitable positions through direct or indirect coupling to obtain the operating information of the power grid 3 such as voltage, frequency, and power. The control unit 13 can include components such as logic circuits to control the operation of the energy storage unit 11. For example, the control unit 13 receives information such as the operating frequency and / or voltage of the power grid 3 measured by the measurement unit 12, and obtains the state of charge of the energy storage unit 11. According to the information such as the operating frequency and / or voltage of the power grid 3 and the state of charge of the energy storage unit 11, the control unit 13 controls the energy storage unit 11 to supply power to the power grid 3 or receive electrical energy from the power grid 3 to achieve power regulation of the power grid 3. The auxiliary power supply device 14 can adopt a suitable power conversion architecture to provide the required auxiliary voltage, and the auxiliary voltage is used to supply power to the internal components in the energy storage system 1, such as cooling systems, communication devices, fire prevention devices, and sensors.

[0076] In Figure 1 the illustrated embodiment, the energy storage unit 11 of the energy storage system 1 includes a plurality of energy storage devices 11_1, 11_2,..., 11_n. The number of the energy storage units 11 in the energy storage system 1 in this case is not limited, and the energy storage unit 11 can be set to include one or more energy storage devices.

[0077] The energy storage device can adopt a suitable architecture to provide the energy storage function. Figure 2 Illustrative Figure 1 a possible implementation manner of the energy storage device 11_n, in Figure 2 the illustrated implementation manner, the energy storage device 11_n includes a plurality of battery modules 111, a plurality of power regulators 112, and a transformer 113. Among them, the plurality of battery modules 111 are respectively electrically connected to the plurality of power regulators 112, the plurality of power regulators 112 are respectively electrically connected to the transformer 113, and the transformer 113 is electrically connected to the grid connection point 2. The battery module 111 can be implemented in ways such as lithium batteries, solid-state batteries, fuel cells, or thermal energy batteries. In some embodiments, the battery module 111 further includes a DC-DC converter (direct current to direct current converter) for converting the electrical energy provided by the energy storage battery into an appropriate voltage and supplying it to the power regulator 112, or converting the electrical energy received from the power regulator 112 into an appropriate voltage and storing it in the battery module 111 to ensure voltage stability. The power regulator 112 is used to perform bidirectional electrical energy conversion and can, for example, adopt a bidirectional DC / AC converter. The transformer 113 is used for the transmission and step-up / step-down adjustment of alternating current, and can be set to have an isolation function or set to a non-isolation architecture. In Figure 2In the illustrated embodiment, the transformer 113 may be a multi-winding transformer that has a plurality of windings on one side connected to a plurality of power regulators 112. In another embodiment, the energy storage device 11_n includes a plurality of transformers. In another embodiment, the energy storage device includes an electrically connected battery module 111, a power regulator 112, and a transformer 113, where the transformer 113 is electrically connected to the grid connection point 2. In another embodiment, the energy storage device includes an electrically connected battery module 111 and a power regulator 112, where the power regulator 112 is electrically connected to the grid connection point 2, and the power regulator 112 directly supplies electrical energy to the power grid 3 or receives electrical energy from the power grid 3 via the grid connection point 2 without passing through a transformer.

[0078] The specifications for grid ancillary services may vary in different regions or among different power utilities. Please refer to Figure 3 for an embodiment which is a schematic diagram of the reference relationship between the regulation ratio of the power regulation provided by the energy storage system 1 and the operating frequency of the power grid 3, showing the upper and lower limits of the regulation ratio of the power regulation provided by the energy storage system 1 corresponding to different operating frequencies of the power grid 3. The regulation ratio of the power regulation provided by the energy storage system 1 is controlled by its control unit 13, where the maximum value of the power regulation is a predefined capacity (for example, a power regulation capacity of 10 MW agreed upon with the power utility). When the control unit 13 sets the regulation ratio of the power regulation of the energy storage system 1 to be greater than 0 (i.e., greater than 0 and less than or equal to 100%), the control unit 13 sets the energy storage unit 11 to supply power to the power grid 3 at the regulation ratio of the predefined capacity; when the control unit 13 sets the regulation ratio of the power regulation of the energy storage system 1 to be less than 0 (i.e., less than 0 and greater than or equal to -100%), the control unit 13 sets the energy storage unit 11 to charge from the power grid 3 at the absolute value of the regulation ratio of the predefined capacity (for the sake of simplicity, when referring to the energy storage unit 11 charging from the power grid 3 in the following paragraphs, the "absolute value" of the "regulation ratio of the absolute value" will be omitted). In addition, it should be noted that Figure 3 the curve in is formed by connecting a plurality of discrete reference points, where each reference point represents the upper limit value and / or the lower limit value of the regulation ratio corresponding to an operating frequency.

[0079] If it is necessary to comply with the Figure 3 power regulation specifications, when the operating frequency of the power grid 3 is greater than or equal to the first frequency fr1 and less than or equal to the second frequency fr2, the regulation ratio of the power regulation of the energy storage system 1 should be set to be greater than or equal to the first input boundary value IL1 and less than or equal to the first output boundary value OL1. Figure 3 The f0 in may be the default power supply frequency of the power grid 3, for example: 50 Hz or 60 Hz.

[0080] When the operating frequency of the power grid 3 is greater than or equal to the third frequency fr3 and less than or equal to the first frequency fr1, the adjustment ratio of the power regulation of the energy storage system 1 should be set to be greater than or equal to the first input boundary value IL1 and less than or equal to the second output boundary value OL2. When the operating frequency decreases from the first frequency fr1 to the third frequency fr3, the multiple first upper limit values of the adjustment ratio corresponding to the change in the operating frequency increase correspondingly from the first output boundary value OL1 to the second output boundary value OL2, and the multiple first lower limit values of the adjustment ratio corresponding to the change in the operating frequency increase correspondingly from the first input boundary value IL1 to the second output boundary value OL2.

[0081] When the operating frequency of the power grid 3 is greater than or equal to the second frequency fr2 and less than or equal to the fourth frequency fr4, the adjustment ratio of the power regulation of the energy storage system 1 should be set to be greater than or equal to the second input boundary value IL2 and less than or equal to the first output boundary value OL1. When the operating frequency increases from the second frequency fr2 to the fourth frequency fr4, the multiple second upper limit values of the adjustment ratio corresponding to the change in the operating frequency decrease correspondingly from the first output boundary value OL1 to the second input boundary value IL2, and the multiple second lower limit values of the adjustment ratio corresponding to the change in the operating frequency decrease correspondingly from the first input boundary value IL1 to the second input boundary value IL2.

[0082] When the operating frequency of the power grid 3 is greater than or equal to the fifth frequency fr5 and less than or equal to the third frequency fr3, the adjustment ratio of the power regulation of the energy storage system 1 should be set to be greater than or equal to the second output boundary value OL2 and less than or equal to the third output boundary value OL3. When the operating frequency decreases from the third frequency fr3 to the fifth frequency fr5, the adjustment ratio corresponding to the change in the operating frequency increases correspondingly from the second output boundary value OL2 to the third output boundary value OL3. When the operating frequency of the power grid 3 is less than the fifth frequency fr5, the adjustment ratio of the power regulation of the energy storage system 1 should be set to be equal to the third output boundary value OL3.

[0083] When the operating frequency of the power grid 3 is greater than or equal to the fourth frequency fr4 and less than or equal to the sixth frequency fr6, the adjustment ratio of the power regulation of the energy storage system 1 should be set to be greater than or equal to the third input boundary value IL3 and less than or equal to the second input boundary value IL2. When the operating frequency increases from the fourth frequency fr4 to the sixth frequency fr6, the adjustment ratio corresponding to the change in the operating frequency decreases correspondingly from the second input boundary value IL2 to the third input boundary value IL3. When the operating frequency of the power grid 3 is greater than the sixth frequency fr6, the adjustment ratio of the power regulation of the energy storage system 1 should be set to be equal to the third input boundary value IL3.

[0084] At Figure 3In the embodiments, the numerical values of the boundary values are OL3 > OL2 > OL1 > IL1 > IL2 > Il3, and the numerical values of the frequencies are fr6 > fr4 > fr2 > f0 > fr1 > fr3 > fr5. However, the specific numerical values of the foregoing frequencies, input boundary values, and output boundary values depend on the frequency response specifications of grid auxiliary services in each region or by each power operator. However, the relative magnitude relationships between the frequencies and between the input boundary values and output boundary values can be similar to those shown in Figure 3 as shown.

[0085] During the operation of the energy storage system 1, the control unit 13 can set the adjustment ratio of the power adjustment of the energy storage system 1 according to conditions such as the state of charge of the energy storage unit 11, the operating frequency of the power grid 3, and the efficiency of the energy storage system 1, so that the energy storage unit 11 supplies power to or charges from the power grid 3 at a regulated ratio of the agreed capacity. The specific setting method is illustrated as follows.

[0086] The control unit 13 evaluates the state of charge of the energy storage unit 11. For example, when the state of charge of the energy storage unit 11 is greater than the first power amount, the control unit 13 determines that the energy storage unit 11 is in a normal power state; when the state of charge of the energy storage unit 11 is less than the first power amount, the control unit 13 determines that the energy storage unit 11 is in a low power state. When the state of charge of the energy storage unit 11 is greater than the second power amount (the second power amount is greater than the first power amount), the control unit 13 determines that the energy storage unit 11 is in a high power state. The specific numerical values of the first power amount and the second power amount can be determined according to actual needs. In another embodiment, the energy storage system 1 can be set to provide a power adjustment function corresponding to one or more of the three states. For example, it can be set to provide power adjustment only corresponding to the normal power and low power states, set to provide power adjustment only corresponding to the high power and low power states, or set to provide power adjustment only corresponding to the normal power and high power states, and use the following methods to provide the power adjustment function for each state of charge.

[0087] Figure 4A FIG. is a schematic diagram of an embodiment of the adjustment ratio of the power adjustment provided by the energy storage system 1 corresponding to the operating frequency of the power grid 3 when the energy storage unit 11 is in a normal power state. Figure 4A The curve in is formed by connecting a plurality of discrete working points, where each working point represents the adjustment ratio corresponding to an operating frequency. When the energy storage unit 11 is in a normal power state, as shown in Figure 4AAs shown, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the first frequency boundary value f11 and less than or equal to the second frequency boundary value f12 (i.e., between the operating point 1E and the operating point 1F), the control unit 13 sets the adjustment ratio of the power adjustment to the first operation ratio R11, where the first operation ratio R11 is less than or equal to 0 and greater than or equal to the first input boundary value IL1. In addition, the control unit 13 sets the first frequency boundary value f11 to be less than the first frequency fr1, and / or sets the second frequency boundary value f12 to be greater than the second frequency fr2, that is, in this embodiment, at least one of the first two conditions is satisfied. In some embodiments, the control unit 13 sets the first operation ratio R11 to zero, which means that the energy storage system 1 does not supply electrical energy to the power grid 3 and does not receive electrical energy from the power grid 3 either. In other embodiments, the energy storage system 1 includes an auxiliary power supply device 14 (such as Figure 1 shown), so the control unit 13 sets the first operation ratio R11 to be less than zero, so that the input electrical energy received by the energy storage system 1 from the power grid 3 is greater than or equal to the auxiliary electrical energy required by the auxiliary power supply device 14. At this time, the auxiliary power supply device 14 is substantially directly powered by the power grid 3. In this frequency range where power adjustment is not required, by setting the first operation ratio R11 to be less than zero and using the power grid 3 to directly supply power to the auxiliary power supply device 14, it will not cause a burden on the power grid 3, and can avoid the energy loss of storing electrical energy in the energy storage unit 11 first and then supplying it to the auxiliary power supply device 14, and can avoid unnecessary charge and discharge to extend the service life of the energy storage unit 11.

[0088] When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the third frequency fr3 and less than or equal to the third frequency boundary value f13 (i.e., between the operating point 1A and the operating point 1D), the control unit 13 sets the adjustment ratio of the power adjustment to be less than or equal to the second output boundary value OL2 and greater than or equal to the second operation ratio R12, where the third frequency boundary value f13 is greater than the third frequency fr3 and less than the first frequency boundary value f11. The second operation ratio R12 is greater than the first operation ratio R11, and the efficiency value of the energy storage system 1 supplying power to the power grid 3 at the second operation ratio R12 is greater than a first efficiency threshold TH1 compared to the efficiency value of the energy storage system 1 supplying power to the power grid 3 at the first operation ratio R11. As Figure 4A shown, when the operating frequency of the power grid 3 decreases from the first frequency boundary value f11 to the third frequency boundary value f13, the adjustment ratio of the power adjustment correspondingly jumps from the first operation ratio R11 to the second operation ratio R12.

[0089] When the energy storage unit 11 is in a normal power state, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fourth frequency boundary value f14 and less than or equal to the third frequency boundary value f13 (i.e., between the operating point 1C and the operating point 1D), the control unit 13 sets the adjustment ratio of the power adjustment to be substantially equal to (i.e., the error is within the allowable range) the first upper limit value corresponding to the operating frequency. In addition, the control unit 13 sets the fourth frequency boundary value f14 to be greater than the third frequency fr3 and less than the third frequency boundary value f13. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fifth frequency boundary value f15 and less than or equal to the fourth frequency boundary value f14 (i.e., between the operating point 1B and the operating point 1C), the control unit 13 sets the adjustment ratio of the power adjustment to be less than or equal to the first upper limit value corresponding to the operating frequency at the fifth frequency boundary value f15 and greater than or equal to the first upper limit value corresponding to the operating frequency at the fourth frequency boundary value f14, and the control unit 13 sets the adjustment ratio of the power adjustment to increase or remain fixed as the operating frequency decreases ( Figure 4A taking remaining fixed as an example). In addition, the control unit 13 sets the fifth frequency boundary value f15 to be greater than the third frequency fr3 and less than the fourth frequency boundary value f14. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the third frequency fr3 and less than or equal to the fifth frequency boundary value f15 (i.e., between the operating point 1A and the operating point 1B), the control unit 13 sets the adjustment ratio of the power adjustment to increase as the operating frequency decreases. For example, the control unit 13 sets the adjustment ratio of the power adjustment to be substantially equal to the first lower limit value corresponding to the operating frequency.

[0090] When the operating frequency of the power grid 3 measured by the measurement unit 12 is less than or equal to the third frequency fr3, in this embodiment, the power operator does not give the energy storage system 1 room for adjustment (see Figure 3 ), so the relationship between the adjustment ratio of the power adjustment provided by the energy storage system 1 and the operating frequency of the power grid 3 is the same as that shown in Figure 3 .

[0091] In addition, when the energy storage unit 11 is in a normal power state, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the sixth frequency boundary value f16 and less than or equal to the fourth frequency fr4 (i.e., between the operating point 1G and the operating point 1J), the control unit 13 sets the adjustment ratio of the power adjustment to be less than or equal to the fourth operation ratio R14 and greater than or equal to the second input boundary value IL2, where the sixth frequency boundary value f16 is greater than the second frequency boundary value f12 and less than the fourth frequency fr4. The fourth operation ratio R14 is less than the first operation ratio R11, and the efficiency value of the energy storage unit 11 charging from the power grid 3 at the fourth operation ratio R14 is greater than the efficiency value of the energy storage unit 11 charging from the power grid 3 at the first operation ratio R11 by a second efficiency threshold TH2. As Figure 4AAs shown, when the operating frequency of the power grid 3 increases from the second frequency boundary value f12 to the sixth frequency boundary value f16, the adjustment ratio of the power adjustment correspondingly decreases from the first operating ratio R11 to the fourth operating ratio R14.

[0092] When the energy storage unit 11 is in a normal state of charge, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the sixth frequency boundary value f16 and less than or equal to the seventh frequency boundary value f17 (i.e., between the operating points 1G and 1H), the control unit 13 sets the adjustment ratio of the power adjustment to be substantially equal to the second lower limit value corresponding to the operating frequency. In addition, the control unit 13 sets the seventh frequency boundary value f17 to be greater than the sixth frequency boundary value f16 and less than the fourth frequency fr4. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the seventh frequency boundary value f17 and less than or equal to the eighth frequency boundary value f18 (i.e., between the operating points 1H and 1I), the control unit 13 sets the adjustment ratio of the power adjustment to be less than or equal to the second lower limit value corresponding to the operating frequency at the seventh frequency boundary value f17 and greater than or equal to the second lower limit value corresponding to the operating frequency at the eighth frequency boundary value f18, and the control unit 13 sets the adjustment ratio of the power adjustment to decrease or remain fixed as the operating frequency increases ( Figure 4A taking remaining fixed as an example). In addition, the control unit 13 sets the eighth frequency boundary value f18 to be greater than the seventh frequency boundary value f17 and less than the fourth frequency fr4. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the eighth frequency boundary value f18 and less than or equal to the fourth frequency fr4 (i.e., between the operating points 1I and 1J), the control unit 13 sets the adjustment ratio of the power adjustment to decrease as the operating frequency increases. For example, the control unit 13 sets the adjustment ratio of the power adjustment to be substantially equal to the second upper limit value corresponding to the operating frequency.

[0093] When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fourth frequency fr4, in this embodiment, the power operator does not give the energy storage system 1 room for adjustment (see Figure 3 ), so the relationship between the adjustment ratio of the power adjustment provided by the energy storage system 1 and the operating frequency of the power grid 3 is the same as that Figure 3 shown.

[0094] Figure 4B FIG. is a schematic diagram of an embodiment of the charge-discharge efficiency of the energy storage system 1 and the adjustment ratio of the power adjustment provided by it when the energy storage unit 11 is in a normal state of charge, Figure 4B in which the right curve is the power supply efficiency curve when the energy storage system 1 supplies power to the power grid 3, and Figure 4B the left curve in FIG. is the charging efficiency curve when the energy storage system 1 charges the energy storage unit 11 from the power grid 3, Figure 4BThe power supply efficiency curve and the charging efficiency curve are not necessarily linear or symmetric curves. If the energy storage system 1 selects a poor regulation ratio, it will result in poor efficiency of the energy storage system 1, and may even cause damage to the energy storage system 1, reducing its charge-discharge performance and service life. For example, when the operating frequency of the power grid 3 is the first frequency boundary value f11, although the energy storage system 1 can select to supply power to the power grid 3 at the regulation ratio of the first output boundary value OL1, however, from Figure 4B it can be seen that when the energy storage system 1 supplies power at the regulation ratio of the first output boundary value OL1, the efficiency of the energy storage system 1 is still poor. Therefore, in this embodiment, the energy storage system 1 waits until the operating frequency of the power grid 3 drops to the third frequency boundary value f13, and then supplies power to the power grid 3 at the regulation ratio of the second operation ratio R12. From Figure 4B it can be seen that compared with the regulation ratio of the first output boundary value OL1, the operating efficiency of the energy storage system 1 corresponding to the second operation ratio R12 is higher, and it can supply power to the power grid 3 more efficiently. Referring to Figure 3 , Figure 4A and Figure 4B , in an embodiment, when the energy storage unit 11 is in a normal power state, when the operating frequency of the power grid 3 drops from the third frequency boundary value f13 to the third frequency fr3, the efficiency of the first upper limit value of the regulation ratio corresponding to this operating frequency may decrease with the decrease of the operating frequency in some sections (such as the curve corresponding to the section between the second operation ratio R12, the third operation ratio R13 and the second output boundary value OL2 in the regulation ratio in Figure 4B ), then the energy storage system 1 needs to select a regulation ratio with a better efficiency value to supply power to the power grid 3. For example: when the operating frequency of the power grid 3 is between the third frequency boundary value f13 and the fourth frequency boundary value f14, the energy storage system 1 can use the first upper limit value of these regulation ratios to supply power to the power grid 3, and the corresponding efficiency curve in Figure 4B is the rising curve corresponding to the section between the second operation ratio R12 and the third operation ratio R13 in the regulation ratio. Since the efficiency value of the regulation ratio corresponding to the third operation ratio R13 is substantially the best, and when the regulation ratio is greater than the third operation ratio R13, the corresponding efficiency value will start to decrease, so when the operating frequency of the power grid 3 is between the fourth frequency boundary value f14 and the fifth frequency boundary value f15, the energy storage system 1 supplies power to the power grid 3 at the regulation ratio of the third operation ratio R13. When the operating frequency of the power grid 3 is between the fifth frequency boundary value f15 and the third frequency fr3, since the regulation ratio of the energy storage system 1 must be greater than or equal to the first lower limit value of the regulation ratio, the energy storage system 1 uses the first lower limit value substantially corresponding to these regulation ratios to supply power to the power grid 3, and the corresponding efficiency curve in Figure 4BThe curve corresponding to the section where the adjustment ratio is between the third operation ratio R13 and the second output boundary value OL2. In one embodiment, the first lower limit value of the adjustment ratio corresponding to the fifth frequency boundary value f15 may be greater than the third operation ratio R13. Therefore, when the operating frequency of the power grid 3 is the fifth frequency boundary value f15, the energy storage system 1 must supply power to the power grid 3 at the first lower limit value of the adjustment ratio substantially corresponding to the operating frequency.

[0095] In one embodiment, the difference between the efficiency of the energy storage system 1 at the second operation ratio R12 and the efficiency at the first operation ratio R11 of the adjustment ratio needs to be greater than the first efficiency threshold TH1 as the basis for selecting the third frequency boundary value f13. That is, it is necessary to select the third frequency boundary value f13 corresponding to the second operation ratio R12 of the adjustment ratio on the premise that the difference between the efficiency of the energy storage system 1 at the second operation ratio R12 and the efficiency at the first operation ratio R11 of the adjustment ratio is greater than the first efficiency threshold TH1. In another embodiment, when the operating frequency of the power grid 3 is between the first critical frequency fx and the default power supply frequency f0 (see Figure 3 ), the adjustment ratio of the power regulation provided by the energy storage system 1 is the first operation ratio R11; when the operating frequency of the power grid  3 drops to less than or equal to the first critical frequency fx, the energy storage system 1 must supply power to the power grid 3 at an adjustment ratio greater than or equal to zero. At this time, the energy storage system 1 selects the adjustment ratio corresponding to the highest efficiency as the second operation ratio R12 from the allowable adjustment ratio range to supply power to the power grid 3.

[0096] Similarly, in the case where the energy storage unit 11 charges from the power grid 3, when the operating frequency of the power grid 3 is the second frequency boundary value f12, although the energy storage system 1 can choose to charge the energy storage unit 11 from the power grid 3 at the adjustment ratio of the first input boundary value IL1, however, Figure 4B it can be seen that when the energy storage unit 11 charges from the power grid 3 at the adjustment ratio of the first input boundary value IL1, the efficiency of the energy storage system 1 is still not good. Therefore, in this embodiment, the energy storage system 1 waits until the operating frequency of the power grid 3 rises to the sixth frequency boundary value f16, and then the energy storage unit 11 charges from the power grid 3 at the adjustment ratio of the fourth operation ratio R14. Figure 4B It can be seen that compared with the adjustment ratio of the first input boundary value IL1, the operating efficiency of the energy storage system 1 corresponding to the fourth operation ratio R14 is higher, enabling the energy storage unit 11 to charge from the power grid 3 more efficiently. Refer to Figure 3 、 Figure 4A and Figure 4B, in one embodiment, when the energy storage unit 11 is in a normal power state, when the operating frequency of the power grid 3 rises from the sixth frequency boundary value f16 to the fourth frequency fr4, the efficiency of the second lower limit value of the adjustment ratio corresponding to this operating frequency may decrease as the operating frequency rises in some sections (such as Figure 4B the curve corresponding to the section of the adjustment ratio between the fourth operating ratio R14, the fifth operating ratio R15 and the second input boundary value IL2 in Figure 4B ), then the energy storage system 1 needs to select the adjustment ratio with a better efficiency value to charge the energy storage unit 11 from the power grid 3. For example: when the operating frequency of the power grid 3 is between the sixth frequency boundary value f16 and the seventh frequency boundary value f17, the energy storage unit 11 can use the second lower limit value of these adjustment ratios to supply power from the power grid 3, and the corresponding efficiency curve is in Figure 4B the rising curve corresponding to the section of the adjustment ratio between the fourth operating ratio R14 and the fifth operating ratio R15 in

[0097] Since the efficiency value of the adjustment ratio corresponding to the fifth operating ratio R15 is substantially the best, and when the adjustment ratio is less than the fifth operating ratio R15, the corresponding efficiency value will start to decline. Therefore, when the operating frequency of the power grid 3 is between the seventh frequency boundary value f17 and the eighth frequency boundary value f18, the energy storage unit 11 charges from the power grid 3 at the adjustment ratio of the fifth operating ratio R15. When the operating frequency of the power grid 3 is between the eighth frequency boundary value f18 and the fourth frequency fr4, since the adjustment ratio of the energy storage system 1 must be less than or equal to the second upper limit value of the adjustment ratio, the energy storage unit 11 charges from the power grid 3 using substantially the second upper limit value of these adjustment ratios, and the corresponding efficiency curve is in Figure 4B the curve corresponding to the section of the adjustment ratio between the fifth operating ratio R15 and the second input boundary value IL2 in

[0097] In one embodiment, the difference between the efficiency of the energy storage system 1 at the adjustment ratio of the fourth operating ratio R14 and the efficiency at the adjustment ratio of the first operating ratio R11 needs to be greater than the second efficiency threshold TH2 as the basis for selecting the sixth frequency boundary value f16. That is, it is necessary to select the sixth frequency boundary value f16 corresponding to the fourth operating ratio R14 of the adjustment ratio on the premise that the difference between the efficiency of the energy storage system 1 at the adjustment ratio of the fourth operating ratio R14 and the efficiency at the adjustment ratio of the first operating ratio R11 is greater than the second efficiency threshold TH2. In another embodiment, when the operating frequency of the power grid 3 is between the second critical frequency fy and the default power supply frequency f0 (see Figure 3) For all regulation ratios of the power regulation provided by the energy storage system 1, they are all the first operation ratio R11; and when the operating frequency of the power grid 3 rises to be greater than or equal to the second critical frequency fy, the energy storage unit 11 must charge from the power grid 3 at a regulation ratio less than or equal to zero. At this time, the energy storage system 1 selects the regulation ratio corresponding to the highest efficiency within the allowable regulation ratio range to charge the energy storage unit 11 from the power grid 3.

[0098] Figure 4C FIG. is a schematic diagram of another embodiment of the charge-discharge efficiency of the energy storage system 1 and the regulation ratio of the power regulation provided by it when the energy storage unit 11 is in a normal power state. Compared with Figure 4B the embodiment of Figure 4C in the power supply efficiency curve of the embodiment of Figure 4C the efficiency values corresponding to the third operation ratio R13 and / or the second output boundary value OL2 do not reach the optimal value; and in the charge efficiency curve, the efficiency values corresponding to the fifth operation ratio R15 and / or the second input boundary value IL2 do not reach the optimal value. In the embodiment of

[0099] it may be due to the performance limitation of the energy storage system 1, protecting the service life of the energy storage unit 11, or other design considerations that the efficiency of the third operation ratio R13 and / or the fifth operation ratio R15 is not the optimal value. For example: the third operation ratio R13 and the fifth operation ratio R15 can also be set to be equal to the second operation ratio R12 and the fourth operation ratio R14 respectively. However, when the operating frequency of the power grid 3 drops to the third frequency boundary value f13, the energy storage system 1 jumps from the first operation ratio R11 to supply power to the power grid 3 at the regulation ratio of the second operation ratio R12, or when the operating frequency of the power grid 3 rises to the sixth frequency boundary value f16, the energy storage system 1 is adjusted from the first operation ratio R11 to charge from the power grid 3 at the regulation ratio of the fourth operation ratio R14. Both can optimize the regulation of the energy storage system 1 by improving the power supply efficiency and / or the charge efficiency, and can extend the service life of the energy storage unit 11 and reduce power loss.

[0099] In other embodiments, the regulation ratio of the power regulation provided by the energy storage system 1 can also be adjusted correspondingly according to the efficiency curve of the energy storage system 1. For example, Figure 5A FIG. is a schematic diagram of another embodiment of the regulation ratio of the power regulation provided by the energy storage system 1 corresponding to the operating frequency of the power grid 3 when the energy storage unit 11 is in a normal power state. Figure 5B FIG. is a schematic diagram of another embodiment of the efficiency of the energy storage system 1 and the regulation ratio of the power regulation provided by it when the energy storage unit 11 is in a normal power state. Among them, the working points similar to Figure 4A are denoted by the same reference numerals and will not be described in detail here. However, in this embodiment, as Figure 5A and Figure 5BAs shown, when the energy storage system 1 supplies power to the power grid 3, the energy storage system 1 has better or optimal efficiency when supplying power to the power grid 3 at the regulation ratio of the second output boundary value OL2. Correspondingly, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the third frequency fr3 and less than or equal to the third frequency boundary value f13 (i.e., between the operating point 1A and the operating point 1D), the control unit 13 sets the regulation ratio of the power regulation to be substantially equal to the first upper limit value corresponding to the operating frequency, so as to optimize the efficiency of the energy storage system 1. In addition, when the energy storage unit 11 charges from the power grid 3, the energy storage system 1 has better or optimal efficiency when the energy storage unit 11 charges from the power grid 3 at the regulation ratio of the second input boundary value IL2. Correspondingly, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the sixth frequency boundary value f16 and less than or equal to the fourth frequency fr4 (i.e., between the operating point 1G and the operating point 1J), the control unit 13 sets the regulation ratio of the power regulation to be substantially equal to the second lower limit value corresponding to the operating frequency, so as to optimize the efficiency of the energy storage system 1.

[0100] The efficiency curve of the energy storage system 1 according to another embodiment Figure 6A is a schematic diagram of the regulation ratio of the power regulation provided by the energy storage system 1 corresponding to the operating frequency of the power grid 3 when the energy storage unit 11 is in a normal power state. Figure 6B is a schematic diagram of the efficiency of the energy storage system 1 and the regulation ratio of the power regulation provided by it when the energy storage unit 11 is in a normal power state, where Figure 4A similar operating points are denoted by the same reference numerals and will not be elaborated here. However, in this embodiment, as Figure 6A and Figure 6B shown, when the energy storage system 1 supplies power to the power grid 3, the energy storage system 1 has the best efficiency when supplying power to the power grid 3 at the regulation ratio of the second operating ratio R12. Therefore, during the process that the operating frequency of the power grid 3 decreases from the third frequency boundary value f13 to the third frequency fr3, the energy storage system 1 supplies power to the power grid 3 at the regulation ratio of the second operating ratio R12 until the energy storage system 1 has to supply power to the power grid 3 using the lower limit value of the regulation ratio. Specifically, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fourth frequency boundary value f14a and less than or equal to the third frequency boundary value f13 (i.e., between the operating point 1Ba and the operating point 1D), the control unit 13 sets the regulation ratio of the power regulation to be less than or equal to the first upper limit value corresponding to the operating frequency at the fourth frequency boundary value f14a and greater than or equal to the first upper limit value corresponding to the operating frequency at the third frequency boundary value f13, and the control unit 13 sets the regulation ratio of the power regulation to increase or remain fixed as the operating frequency decreases ( Figure 6ATake maintaining a fixed value as an example for the middle case). In addition, the control unit 13 sets the fourth frequency boundary value f14a to be greater than the third frequency fr3 and less than the third frequency boundary value f13. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the third frequency fr3 and less than or equal to the fourth frequency boundary value f14a (i.e., between the operating point 1A and the operating point 1Ba), the control unit 13 sets the adjustment ratio of the power adjustment to increase as the operating frequency decreases. For example, the adjustment ratio of the power adjustment is set to be substantially equal to the first lower limit value corresponding to the operating frequency. In another embodiment, similar to Figure 4C In the embodiment of, due to the performance limitations of the energy storage system 1, protecting the service life of the energy storage unit 11, or other design considerations, the efficiency value corresponding to the adjustment ratio being the second operating ratio R12 and / or the second output boundary value OL2 may not have reached the optimal value yet. However, when the energy storage system 1 jumps from the first operating ratio R11 to the adjustment ratio of the second operating ratio R12 to supply power to the power grid 3, the energy storage system 1 can be optimally adjusted through the improvement of the power supply efficiency, thereby extending the service life of the energy storage unit 11 and reducing power loss.

[0101] Similarly, in the case where the energy storage unit 11 charges from the power grid 3, the energy storage system 1 has the best efficiency when the energy storage unit 11 charges from the power grid 3 at the adjustment ratio of the fourth operating ratio R14. Therefore, during the process of the operating frequency of the power grid 3 rising from the sixth frequency boundary value f16 to the fourth frequency fr4, the energy storage unit 11 charges from the power grid 3 at the adjustment ratio of the fourth operating ratio R14 until the energy storage unit 11 has to charge from the power grid 3 at the upper limit value of the adjustment ratio. Specifically, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the sixth frequency boundary value f16 and less than or equal to the seventh frequency boundary value f17a (i.e., between the operating point 1G and the operating point 1Ia), the control unit 13 sets the adjustment ratio of the power adjustment to be less than or equal to the second lower limit value corresponding to the operating frequency at the sixth frequency boundary value f16 and greater than or equal to the second lower limit value corresponding to the operating frequency at the seventh frequency boundary value f17a, and the control unit 13 sets the adjustment ratio of the power adjustment to decrease or maintain a fixed value as the operating frequency increases ( Figure 6A Take maintaining a fixed value as an example for the middle case). In addition, the control unit 13 sets the seventh frequency boundary value f17a to be greater than the sixth frequency boundary value f16 and less than the fourth frequency fr4. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the seventh frequency boundary value f17a and less than or equal to the fourth frequency fr4 (i.e., between the operating point 1Ia and the operating point 1J), the control unit 13 sets the adjustment ratio of the power adjustment to decrease as the operating frequency increases. For example, the adjustment ratio of the power adjustment is set to be substantially equal to the second upper limit value corresponding to the operating frequency. In another embodiment, similar to Figure 4CIn an embodiment, due to the efficiency limitation of the energy storage system 1, to protect the service life of the energy storage unit 11, or other design considerations, the efficiency value corresponding to the regulation ratio of the fourth operation ratio R14 and / or the second input boundary value IL2 may not have reached the optimal value yet. However, when the energy storage system 1 is adjusted from the first operation ratio R11 to the regulation ratio of the fourth operation ratio R14 for charging from the power grid 3, the energy storage system 1 can be optimally regulated by improving the charging efficiency, thereby extending the service life of the energy storage unit 11 and reducing power loss.

[0102] Figure 7A FIG. is a schematic diagram of an embodiment of the regulation ratio of the power regulation provided by the energy storage system 1 corresponding to the operating frequency of the power grid 3 when the energy storage unit 11 is in a low power state. Figure 7A The curve in FIG. is formed by connecting a plurality of discrete working points, where each working point represents the regulation ratio corresponding to an operating frequency. In the case where the energy storage unit 11 is in a low power state, as Figure 7A shown, when the operating frequency of the power grid 3 measured by the measuring unit 12 is greater than or equal to the first frequency boundary value f21 and less than or equal to the second frequency boundary value f22 (i.e., between the working point 2D and the working point 2E. For example, the second frequency boundary value f22 can be set to the default power supply frequency f0, set to be less than the default power supply frequency f0, or set to the first frequency boundary value f21), the control unit 13 sets the regulation ratio of the power regulation to the first operation ratio R21, where the first operation ratio R21 is less than or equal to 0 and greater than or equal to the first input boundary value IL1. In addition, the control unit 13 sets the first frequency boundary value f21 to be less than the first frequency fr1, and sets the second frequency boundary value f22 to be greater than the first frequency fr1 and less than the second frequency fr2. In some embodiments, the control unit 13 sets the first operation ratio R21 to zero, which means that the energy storage system 1 does not supply electrical energy to the power grid 3 and does not receive electrical energy from the power grid 3 either. In other embodiments, the energy storage system 1 includes an auxiliary power supply device 14 (as Figure 1 shown), so the control unit 13 sets the first operation ratio R21 to be less than zero, so that the input electrical energy received by the energy storage system 1 from the power grid 3 is greater than or equal to the auxiliary electrical energy required by the auxiliary power supply device 14. At this time, the auxiliary power supply device 14 is substantially directly powered by the power grid 3. In this frequency range where power regulation is not required, by setting the first operation ratio R21 to be less than zero and using the power grid 3 to directly supply power to the auxiliary power supply device 14, it will not cause a burden on the power grid 3, and can avoid the energy loss of storing electrical energy in the energy storage unit 11 first and then supplying it to the auxiliary power supply device 14, and can avoid unnecessary charge and discharge to extend the service life of the energy storage unit 11.

[0103] When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the third frequency fr3 and less than or equal to the third frequency boundary value f23 (i.e., between the operating point 2A and the operating point 2Cb), the control unit 13 sets the adjustment ratio of the power regulation to be less than or equal to the second output boundary value OL2 and greater than or equal to the second operating ratio R22, where the third frequency boundary value f23 is greater than the third frequency fr3 and less than the first frequency boundary value f21. The second operating ratio R22 is greater than the first operating ratio R21, and the efficiency value of the energy storage system 1 supplying power to the power grid 3 at the second operating ratio R22 is greater than the efficiency value of the energy storage system 1 supplying power to the power grid 3 at the first operating ratio R21 by a third efficiency threshold TH3. As Figure 7A shown, when the operating frequency of the power grid 3 decreases from the first frequency boundary value f21 to the third frequency boundary value f23, the adjustment ratio of the power regulation jumps from the first operating ratio R21 to the second operating ratio R22 correspondingly.

[0104] In some embodiments, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fourth frequency boundary value f24 and less than or equal to the third frequency boundary value f23 (i.e., between the operating point 2Ca and the operating point 2Cb), the control unit 13 sets the adjustment ratio of the power regulation to remain fixed as the operating frequency decreases. In addition, the control unit 13 sets the fourth frequency boundary value f24 to be greater than the third frequency fr3 and less than the third frequency boundary value f23. By appropriately selecting the value of the third efficiency threshold TH3 and keeping the adjustment ratio fixed as the operating frequency decreases between the operating point 2Ca and the operating point 2Cb, the energy storage system 1 can provide the function of power regulation for the power grid 3 in a more efficient and less-discharge way, while taking into account both power regulation and the discharge amount of the energy storage system 1 to avoid damaging the energy storage unit 11 due to too low power as much as possible.

[0105] When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fifth frequency boundary value f25 and less than or equal to the fourth frequency boundary value f24 (i.e., between the operating point 2B and the operating point 2Ca), the control unit 13 sets the adjustment ratio of the power regulation to be less than or equal to the first lower limit value corresponding to the operating frequency at the fifth frequency boundary value f25 and greater than or equal to the first lower limit value corresponding to the operating frequency at the fourth frequency boundary value f24, and the control unit 13 sets the adjustment ratio of the power regulation to increase as the operating frequency decreases. In addition, the control unit 13 sets the fifth frequency boundary value f25 to be greater than the third frequency fr3 and less than the fourth frequency boundary value f24. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the third frequency fr3 and less than or equal to the fifth frequency boundary value f25 (i.e., between the operating point 2A and the operating point 2B), the control unit 13 sets the adjustment ratio of the power regulation to increase as the operating frequency decreases, for example, setting the adjustment ratio of the power regulation to be substantially equal to the first lower limit value corresponding to the operating frequency.

[0106] When the operating frequency of the power grid 3 measured by the measurement unit 12 is less than or equal to the third frequency fr3, in this embodiment, the power industry does not give the energy storage system 1 room for adjustment (see Figure 3 ), so the relationship between the adjustment ratio of the power regulation provided by the energy storage system 1 and the operating frequency of the power grid 3 is the same as that Figure 3 shown.

[0107] In addition, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the sixth frequency boundary value f26 and less than or equal to the fourth frequency fr4 (i.e., between the operating point 2F and the operating point 2H), the control unit 13 sets the adjustment ratio of the power regulation to be less than or equal to the fourth operation ratio R24 and greater than or equal to the second input boundary value IL2, where the sixth frequency boundary value f26 is greater than the second frequency boundary value f22 and less than the fourth frequency fr4. The fourth operation ratio R24 is less than the first operation ratio R21, and the efficiency value of the energy storage unit 11 charging from the power grid 3 at the fourth operation ratio R24 is greater than the efficiency value of the energy storage unit 11 charging from the power grid 3 at the first operation ratio R21 by a fourth efficiency threshold TH4. As Figure 7A shown, when the operating frequency of the power grid 3 increases from the second frequency boundary value f22 to the sixth frequency boundary value f26, the adjustment ratio of the power regulation correspondingly decreases from the first operation ratio R21 to the fourth operation ratio R24. In this embodiment, the fourth operation ratio R24 is substantially equal to the first input boundary value IL1.

[0108] In some embodiments, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the sixth frequency boundary value f26 and less than or equal to the second frequency fr2 (i.e., between the operating point 2F and the operating point 2G), the control unit 13 sets the adjustment ratio of the power regulation to be substantially equal to the first input boundary value IL1. In addition, the control unit 13 sets the sixth frequency boundary value f26 to be greater than the second frequency boundary value f22 and less than the second frequency fr2. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the second frequency fr2 and less than or equal to the fourth frequency fr4, the control unit 13 sets the adjustment ratio of the power regulation to decrease as the operating frequency increases, for example, setting the adjustment ratio of the power regulation to be substantially equal to the second lower limit value corresponding to the operating frequency.

[0109] When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fourth frequency fr4, in this embodiment, the power industry does not give the energy storage system 1 room for adjustment (see Figure 3 ), so the relationship between the adjustment ratio of the power regulation provided by the energy storage system 1 and the operating frequency of the power grid 3 is the same as that Figure 3 shown.

[0110] Figure 7BSchematic diagram of an embodiment of the efficiency of energy storage system 1 and the regulation ratio of power regulation provided thereby when energy storage unit 11 is in a low power state. Figure 7B The right curve in [figure] is the power supply efficiency curve when energy storage system 1 supplies power to power grid 3, and Figure 7B the left curve in [figure] is the charging efficiency curve when energy storage system 1 charges energy storage unit 11 from power grid 3. Figure 7B The power supply efficiency curve and the charging efficiency curve are not necessarily linear or symmetric curves. If energy storage system 1 selects a poor regulation ratio, it will result in poor efficiency of energy storage system 1, and may even cause loss of energy storage system 1, reducing its charge-discharge performance and service life. For example, when the operating frequency of power grid 3 is the first frequency boundary value f21, although energy storage system 1 can select to supply power to power grid 3 at a regulation ratio of the first output boundary value OL1, however, as Figure 7B can be seen, when energy storage system 1 supplies power at a regulation ratio of the first output boundary value OL1, the efficiency of energy storage system 1 is still poor. Therefore, in this embodiment, energy storage system 1 waits until the operating frequency of power grid 3 drops to the third frequency boundary value f23, and then supplies power to power grid 3 at a regulation ratio of the second operation ratio R22. As Figure 7B can be seen, compared with the regulation ratio of the first output boundary value OL1, the operating efficiency of energy storage system 1 corresponding to the second operation ratio R22 is higher, and it can supply power to power grid 3 more efficiently. Referring to ​ , ​ and ​ , in an embodiment, when energy storage unit 11 is in a low power state, when the operating frequency of power grid 3 drops from the third frequency boundary value f23 to the third frequency fr3, the efficiency of the first upper limit value of the regulation ratio corresponding to this operating frequency may decrease with the decrease of the operating frequency in some sections (such as ​ the curve corresponding to the section of the regulation ratio between the second operation ratio R22, the third operation ratio R23 and the second output boundary value OL2 in [figure]), then energy storage system 1 needs to balance between efficiency and the power of energy storage unit 11 to select an appropriate regulation ratio to supply power to power grid 3. For example: when the operating frequency of power grid 3 is between the third frequency boundary value f23 and the fourth frequency boundary value f24, energy storage system 1 fixedly uses the regulation ratio of the second operation ratio R22 to supply power to power grid 3, so that energy storage system 1 supplies power regulation function to power grid 3 with relatively high efficiency and low discharge limit, while taking into account power regulation and the discharge amount of energy storage system 1, so as to avoid damage to energy storage unit 11 due to too low power as much as possible. When the operating frequency of power grid 3 is between the fourth frequency boundary value f24 and the fifth frequency boundary value f25, the regulation ratio adopted by energy storage system 1 increases with the decrease of the operating frequency of power grid 3, so that the efficiency of energy storage system 1 gradually increases, and the corresponding efficiency curve is shown in ​The rising curve corresponding to the section where the adjustment ratio is between the second operating ratio R22 and the third operating ratio R23. The efficiency value of the adjustment ratio corresponding to the third operating ratio R23 is substantially the best, and when the adjustment ratio is greater than the third operating ratio R23, the corresponding efficiency value will start to decline. When the operating frequency of the power grid 3 is between the fifth frequency boundary value f25 and the third frequency fr3, since the adjustment ratio of the energy storage system 1 must be greater than or equal to the first lower limit value of the adjustment ratio, the energy storage system 1 supplies power to the power grid 3 by substantially corresponding to the first lower limit value of these adjustment ratios, and the corresponding efficiency curve is at ​ The curve corresponding to the section where the adjustment ratio is between the third operating ratio R23 and the second output boundary value OL2.

[0111] In one embodiment, the difference between the efficiency of the energy storage system 1 at the second operating ratio R22 and the efficiency at the first operating ratio R2 is required to be greater than the third efficiency threshold TH3 as the basis for selecting the third frequency boundary value f23. That is, under the premise that the difference between the efficiency of the energy storage system 1 at the second operating ratio R22 and the efficiency at the first operating ratio R21 is greater than the third efficiency threshold TH3, the third frequency boundary value f23 corresponding to the second operating ratio R22 of the adjustment ratio is selected. In another embodiment, when the operating frequency of the power grid 3 is between the first critical frequency fx and the default power supply frequency f0 (see ​ ), the adjustment ratio of the power regulation provided by the energy storage system 1 is the first operating ratio R21; when the operating frequency of the power grid 3 drops to the first critical frequency fx, the energy storage system 1 must supply power to the power grid 3 with an adjustment ratio greater than or equal to zero. At this time, the energy storage system 1 selects the adjustment ratio corresponding to the highest efficiency as the second operating ratio R22 within the allowable adjustment ratio range to supply power to the power grid 3.

[0112] In the case where the energy storage unit 11 is charged from the power grid 3, since the energy storage unit 11 is already in a low power state, the energy storage system 1 preferentially selects the adjustment ratio to increase the power of the energy storage unit 11. For example, when the operating frequency of the power grid 3 is between the sixth frequency boundary value f26 and the second frequency fr2, the energy storage unit 11 charges from the power grid 3 by substantially corresponding to the lower limit value of these adjustment ratios (i.e., the first input boundary value IL1). When the operating frequency of the power grid 3 is between the second frequency fr2 and the fourth frequency fr4, the energy storage unit 11 charges from the power grid 3 by the second lower limit value of the adjustment ratio substantially corresponding to the operating frequency.

[0113] According to the relatively low state of charge of the energy storage unit 11, the sixth frequency boundary value f26 can also be set as close as possible to the first frequency boundary value f21, and the energy storage unit 11 is charged as soon as possible to avoid damaging the energy storage unit 11. In another embodiment, to maximize the state of charge of the energy storage unit 11, when the operating frequency of the power grid 3 measured by the measuring unit 12 is greater than or equal to the first frequency boundary value f21 and less than or equal to the first frequency fr1, the control unit 13 sets the adjustment ratio of the power adjustment equal to the fourth operation ratio R24 or the first input boundary value IL1. In another embodiment, similar to ​ In the embodiment, due to the performance limitations of the energy storage system 1, protecting the service life of the energy storage unit 11, or other design considerations, in the power supply efficiency curve, the efficiency values corresponding to the second operation ratio R22, the third operation ratio R23, and / or the second output boundary value OL2 do not reach the optimal value; and / or in the charging efficiency curve, the efficiency values corresponding to the fourth operation ratio R24 and / or the second input boundary value IL2 do not reach the optimal value. However, when the operating frequency of the power grid 3 drops to the third frequency boundary value f23, the energy storage system 1 jumps from the first operation ratio R21 to the adjustment ratio of the second operation ratio R22 to supply power to the power grid 3, or when the operating frequency of the power grid 3 rises to the sixth frequency boundary value f26, the energy storage system 1 is adjusted from the first operation ratio R21 to the adjustment ratio of the fourth operation ratio R24 to charge from the power grid 3. Both can optimize the adjustment of the energy storage system 1 by improving the power supply efficiency and / or the charging efficiency, thereby extending the service life of the energy storage unit 11 and reducing power loss.

[0114] ​ FIG. is a schematic diagram of another embodiment of the adjustment ratio of the power adjustment provided by the energy storage system 1 corresponding to the operating frequency of the power grid 3 when the energy storage unit 11 is in a low state of charge, where ​ Similar operating points are denoted by the same reference numerals and will not be described in detail here. However, in this embodiment, as ​ shown, when the operating frequency of the power grid 3 measured by the measuring unit 12 is greater than or equal to the fifth frequency boundary value f25 and less than or equal to the third frequency boundary value f23 (i.e., between the operating points 2B and 2Cb), the control unit 13 sets the adjustment ratio of the power adjustment to be less than or equal to the first lower limit value corresponding to the operating frequency at the fifth frequency boundary value f25 and greater than or equal to the first lower limit value corresponding to the operating frequency at the third frequency boundary value f23, and the control unit 13 sets the adjustment ratio of the power adjustment to increase or remain fixed as the operating frequency decreases ( ​Take the example of increasing as the operating frequency decreases. In the section between operating point 2B and operating point 2Cb, if the control unit 13 sets the adjustment ratio of power regulation to remain fixed as the operating frequency decreases, the energy storage system 1 can provide the power regulation function for the power grid 3 with higher efficiency and lower discharge, while taking into account both power regulation and the discharge amount of the energy storage system 1, so as to avoid damaging the energy storage unit 11 due to too low power as much as possible; if the control unit 13 sets the adjustment ratio of power regulation to increase as the operating frequency decreases, the efficiency of the energy storage system 1 can be improved.

[0115] ​ FIG. is a schematic diagram of an embodiment of the adjustment ratio of power regulation provided by the energy storage system 1 corresponding to the operating frequency of the power grid 3 when the energy storage unit 11 is in a high power state. ​ The curve in FIG. is formed by connecting a plurality of discrete operating points, and each operating point represents the adjustment ratio corresponding to an operating frequency. When the energy storage unit 11 is in a high power state, as ​ shown, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the first frequency boundary value f31 and less than or equal to the second frequency boundary value f32 (i.e., between operating point 3D and operating point 3E, for example: the first frequency boundary value f31 can be set to the default power supply frequency f0, set to be greater than the default power supply frequency f0, or set to the second frequency boundary value f32), the control unit 13 sets the adjustment ratio of power regulation to the first operation ratio R31, where the first operation ratio R31 is less than or equal to 0 and greater than or equal to the first input boundary value IL1. In addition, the control unit 13 sets the second frequency boundary value f32 to be greater than the second frequency fr2, and sets the first frequency boundary value f31 to be greater than the first frequency fr1 and less than the second frequency fr2. In some embodiments, the control unit 13 sets the first operation ratio R31 to zero, which means that the energy storage system 1 does not supply electrical energy to the power grid 3 and does not receive electrical energy from the power grid 3 either. In other embodiments, the energy storage system 1 includes an auxiliary power supply device 14 (as ​ shown), so the control unit 13 sets the first operation ratio R31 to be less than zero, so that the input electrical energy received by the energy storage system 1 from the power grid 3 is greater than or equal to the auxiliary electrical energy required by the auxiliary power supply device 14. At this time, the auxiliary power supply device 14 is substantially directly powered by the power grid 3. In this frequency range where power regulation is not required, by setting the first operation ratio R31 to be less than zero and using the power grid 3 to directly supply power to the auxiliary power supply device 14, it will not cause a burden on the power grid 3, and can avoid the energy loss of storing electrical energy in the energy storage unit 11 first and then supplying it to the auxiliary power supply device 14, and can avoid unnecessary charge and discharge and extend the service life of the energy storage unit 11.

[0116] When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the third frequency fr3 and less than or equal to the third frequency boundary value f33 (i.e., between the operating point 3A and the operating point 3C), the control unit 13 sets the adjustment ratio of the power regulation to be less than or equal to the second output boundary value OL2 and greater than or equal to the second operating ratio R32, where the third frequency boundary value f33 is greater than the third frequency fr3 and less than the first frequency boundary value f31. The second operating ratio R32 is greater than the first operating ratio R31, and the efficiency value of the energy storage system 1 supplying power to the power grid 3 at the second operating ratio R32 is greater than a fifth efficiency threshold TH5 compared to the efficiency value of the energy storage system 1 supplying power to the power grid 3 at the first operating ratio R31. As ​ shown, when the operating frequency of the power grid 3 decreases from the first frequency boundary value f31 to the third frequency boundary value f33, the adjustment ratio of the power regulation correspondingly jumps from the first operating ratio R31 to the second operating ratio R32. In this embodiment, the second operating ratio R32 is substantially equal to the first output boundary value OL1.

[0117] In some embodiments, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the first frequency fr1 and less than or equal to the third frequency boundary value f33 (i.e., between the operating point 3B and the operating point 3C), the control unit 13 sets the adjustment ratio of the power regulation to be substantially equal to the first output boundary value OL1. In addition, the control unit 13 sets the third frequency boundary value f33 to be greater than the first frequency fr1 and less than the first frequency boundary value f31. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the third frequency fr3 and less than or equal to the first frequency fr1, the control unit 13 sets the adjustment ratio of the power regulation to increase as the operating frequency decreases, for example, setting the adjustment ratio of the power regulation to be substantially equal to the first upper limit value corresponding to the operating frequency.

[0118] When the operating frequency of the power grid 3 measured by the measurement unit 12 is less than or equal to the third frequency fr3, in this embodiment, the power operator does not give the energy storage system 1 room for adjustment (see ​ ), so the relationship between the adjustment ratio of the power regulation provided by the energy storage system 1 and the operating frequency of the power grid 3 is the same as that ​ shown.

[0119] In addition, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fourth frequency boundary value f34 and less than or equal to the fourth frequency fr4 (i.e., between the operating point 3Fa and the operating point 3H), the control unit 13 sets the adjustment ratio of the power adjustment to be less than or equal to the third operating ratio R33 and greater than or equal to the second input boundary value IL2, where the fourth frequency boundary value f34 is greater than the second frequency boundary value f32 and less than the fourth frequency fr4. The third operating ratio R33 is less than the first operating ratio R31, and the efficiency value of the energy storage unit 11 charging from the power grid 3 at the third operating ratio R33 is greater than the first efficiency threshold TH6 compared to the efficiency value of the energy storage unit 11 charging from the power grid 3 at the first operating ratio R31. As ​ shown, when the operating frequency of the power grid 3 increases from the second frequency boundary value f32 to the fourth frequency boundary value f34, the adjustment ratio of the power adjustment correspondingly decreases from the first operating ratio R31 to the third operating ratio R33.

[0120] In some embodiments, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fourth frequency boundary value f34 and less than or equal to the fifth frequency boundary value f35 (i.e., between the operating point 3Fa and the operating point 3Fb), the control unit 13 sets the adjustment ratio of the power adjustment to remain fixed as the operating frequency increases. In addition, the control unit 13 sets the fifth frequency boundary value f35 to be greater than the fourth frequency boundary value f34 and less than the fourth frequency fr4. By keeping the adjustment ratio fixed as the operating frequency increases between the operating point 3Fa and the operating point 3Fb, the energy storage system 1 can receive electrical energy from the power grid 3 more efficiently and with a lower limit, to provide the function of power adjustment for the power grid 3, while taking into account both power adjustment and the charging amount of the energy storage system 1, so as to avoid the excessive charge of the energy storage unit 11 as much as possible.

[0121] When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fifth frequency boundary value f35 and less than or equal to the sixth frequency boundary value f36 (i.e., between the operating point 3Fb and the operating point 3G), the control unit 13 sets the adjustment ratio of the power adjustment to be less than or equal to the second upper limit value corresponding to the operating frequency at the fifth frequency boundary value f35 and greater than or equal to the second upper limit value corresponding to the operating frequency at the sixth frequency boundary value f36, and the control unit 13 sets the adjustment ratio of the power adjustment to decrease as the operating frequency increases. In addition, the control unit 13 sets the sixth frequency boundary value f36 to be greater than the fifth frequency boundary value f35 and less than the fourth frequency fr4. When the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the sixth frequency boundary value f36 and less than or equal to the fourth frequency fr4 (i.e., between the operating point 3G and the operating point 3H), the control unit 13 sets the adjustment ratio of the power adjustment to decrease as the operating frequency increases, for example, setting the adjustment ratio of the power adjustment to be substantially equal to the second upper limit value corresponding to the operating frequency.

[0122] When the operating frequency of the power grid 3 measured by the measuring unit 12 is greater than or equal to the fourth frequency fr4, in this embodiment, the power company does not give the energy storage system 1 any room for adjustment (see ​ ), so the relationship between the power regulation ratio provided by the energy storage system 1 and the operating frequency of the power grid 3 is ​ Same as shown.

[0123] ​ FIG. 1 is a schematic diagram of an embodiment of the efficiency of the energy storage system 1 and the adjustment ratio of the power adjustment provided by the energy storage unit 11 when the energy storage unit 11 is in a high power state. ​ The right curve in the middle is the power supply efficiency curve when the energy storage system 1 supplies power to the grid 3. ​ The left curve in the middle is the charging efficiency curve when the energy storage system 1 charges the energy storage unit 11 from the power grid 3. ​ The power supply efficiency curve and charging efficiency curve are not necessarily linear or symmetrical curves. If the energy storage system 1 selects a poor regulation ratio, the efficiency of the energy storage system 1 will be poor, and it may even cause loss of the energy storage system 1, thereby reducing its charging and discharging performance and service life. When the energy storage system 1 supplies power to the power grid 3, since the energy storage unit 11 is already in a high power state, the energy storage system 1 selects the regulation ratio with priority given to reducing the power of the energy storage unit 11. For example, when the operating frequency of the power grid 3 is between the third frequency boundary value f33 and the first frequency fr1, the energy storage system 1 supplies power to the power grid 3 at the upper limit value (i.e., the first output boundary value OL1) that substantially corresponds to these regulation ratios. When the operating frequency of the power grid 3 is between the first frequency fr1 and the third frequency fr3, the energy storage system 1 supplies power to the power grid 3 at the first upper limit value of the regulation ratio that substantially corresponds to the operating frequency.

[0124] In the case where the energy storage unit 11 is charged from the grid 3, when the operating frequency of the grid 3 is the second frequency limit value f32, the energy storage system 1 can choose to charge the energy storage unit 11 from the grid 3 at the adjustment ratio of the first input limit value IL1. ​ It can be seen that when the energy storage unit 11 is charged from the grid 3 at the adjustment ratio of the first input boundary value IL1, the efficiency of the energy storage system 1 is still poor. Therefore, in this embodiment, the energy storage system 1 waits until the operating frequency of the grid 3 rises to the fourth frequency boundary value f34, and then the energy storage unit 11 is charged from the grid 3 at the adjustment ratio of the third operating ratio R33. ​ It can be seen that compared with the adjustment ratio of the first input boundary value IL1, the operation efficiency of the energy storage system 1 corresponding to the third operation ratio R33 is higher, and the energy storage unit 11 can be charged from the power grid 3 more efficiently. ​ 、 ​ and ​, in an embodiment, when the energy storage unit 11 is in a high power state, when the operating frequency of the power grid 3 rises from the fourth frequency boundary value f34 to the fourth frequency fr4, the efficiency of the second upper limit value of the adjustment ratio corresponding to this operating frequency may decrease as the operating frequency rises in some sections (such as ​ the curve corresponding to the section of the adjustment ratio between the third operating ratio R33, the fourth operating ratio R34, and the second input boundary value IL2 in ​ ), then the energy storage system 1 needs to balance between the efficiency and the power of the energy storage unit 11 to select an appropriate adjustment ratio to supply power to the power grid 3. For example: when the operating frequency of the power grid 3 is between the fourth frequency boundary value f34 and the fifth frequency boundary value f35, the energy storage system 1 fixedly uses the adjustment ratio of the third operating ratio R33 to charge the energy storage unit 11 from the power grid 3, so that the energy storage system 1 receives electric energy from the power grid 3 more efficiently and with a lower limit, to provide the function of power regulation for the power grid 3, while taking into account power regulation and the charging amount of the energy storage system 1 to avoid the power of the energy storage unit 11 being too high as much as possible. When the operating frequency of the power grid 3 is between the fifth frequency boundary value f35 and the sixth frequency boundary value f36, the adjustment ratio adopted by the energy storage system 1 decreases as the operating frequency of the power grid 3 rises, so that the efficiency of the energy storage system 1 gradually increases, and the corresponding efficiency curve is in ​ the rising curve corresponding to the section of the adjustment ratio between the third operating ratio R33 and the fourth operating ratio R34 in

[0125] The efficiency value corresponding to the adjustment ratio of the fourth operating ratio R34 is substantially the best, and when the adjustment ratio is less than the fourth operating ratio R34, the corresponding efficiency value will start to decline. When the operating frequency of the power grid 3 is between the sixth frequency boundary value f36 and the fourth frequency fr4, since the adjustment ratio of the energy storage system 1 must be less than or equal to the second upper limit value of the adjustment ratio, the energy storage unit 11 charges from the power grid 3 substantially corresponding to the second upper limit value of these adjustment ratios, and the corresponding efficiency curve is in ​ the curve corresponding to the section of the adjustment ratio between the fourth operating ratio R34 and the second input boundary value IL2 in

[0125] In an embodiment, the difference between the efficiency of the energy storage system 1 at the third operating ratio R33 and the efficiency at the first operating ratio R31 is required to be greater than the sixth efficiency threshold TH6 as the basis for selecting the fourth frequency boundary value f34, that is, it is necessary to select the fourth frequency boundary value f34 corresponding to the third operating ratio R33 under the premise that the difference between the efficiency of the energy storage system 1 at the third operating ratio R33 and the efficiency at the first operating ratio R31 is greater than the sixth efficiency threshold TH6. In another embodiment, when the operating frequency of the power grid 3 is between the second critical frequency fy and the default power supply frequency f0 (see ​) For all power regulations provided by the energy storage system 1, the regulation ratio is the first operation ratio R31. When the operating frequency of the power grid 3 rises to the second critical frequency fy, the energy storage system 1 must supply power to the power grid 3 at a regulation ratio less than or equal to zero. At this time, the energy storage system 1 selects the regulation ratio corresponding to the highest efficiency within the allowable regulation ratio range as the third operation ratio R33 to charge the energy storage unit 11 from the power grid 3.

[0126] According to the relatively high state of charge of the energy storage unit 11, the third frequency boundary value f33 can also be set as close as possible to the second frequency boundary value f32 to discharge the energy storage unit 11 as soon as possible. In another embodiment, to minimize the state of charge of the energy storage unit 11 as much as possible, when the operating frequency of the power grid 3 measured by the measuring unit 12 is greater than or equal to the first frequency boundary value f31 and less than or equal to the second frequency fr2, the control unit 13 sets the regulation ratio of the power regulation to be equal to the second operation ratio R32 or the first output boundary value OL1.

[0127] In another embodiment, similar to ​ the embodiment, due to possible limitations in the performance of the energy storage system 1, protection of the service life of the energy storage unit 11, or other design considerations, in the power supply efficiency curve, the efficiency values corresponding to the second operation ratio R32 and / or the second output boundary value OL2 do not reach the optimal value; and / or in the charging efficiency curve, the efficiency values corresponding to the third operation ratio R33, the fourth operation ratio R34, and / or the second input boundary value IL2 do not reach the optimal value. However, when the operating frequency of the power grid 3 drops to the third frequency boundary value f33, the energy storage system 1 jumps from the first operation ratio R31 to supply power to the power grid 3 at the regulation ratio of the second operation ratio R32, or when the operating frequency of the power grid 3 rises to the fourth frequency boundary value f34, the energy storage system 1 adjusts down from the first operation ratio R31 to charge from the power grid 3 at the regulation ratio of the third operation ratio R33, both of which can optimize the regulation of the energy storage system 1 through the improvement of power supply efficiency and / or charging efficiency, thereby extending the service life of the energy storage unit 11 and reducing electrical energy loss.

[0128] ​ Schematic diagram of another embodiment of the regulation ratio of the power regulation provided by the energy storage system 1 corresponding to the operating frequency of the power grid 3 when the energy storage unit 11 is in a high state of charge, where the working points similar to ​ are denoted by the same reference numerals and will not be elaborated here. However, in this embodiment, as ​As shown, when the operating frequency of the power grid 3 measured by the measurement unit 12 is greater than or equal to the fourth frequency boundary value f34 and less than or equal to the sixth frequency boundary value f36 (i.e., between the operating points 3Fa and 3G), the control unit 13 sets the adjustment ratio of the power regulation to be less than or equal to the second upper limit value corresponding to the operating frequency at the fourth frequency boundary value f34 and greater than or equal to the second upper limit value corresponding to the operating frequency at the sixth frequency boundary value f36, and the control unit 13 sets the adjustment ratio of the power regulation to remain fixed or decrease as the operating frequency increases ( ​ taking the example of decreasing as the operating frequency increases in ​ . In the section between the operating points 3Fa and 3G, if the control unit 13 sets the adjustment ratio of the power regulation to remain fixed as the operating frequency increases, the energy storage system 1 can receive electrical energy from the power grid 3 more efficiently and with a lower limit, so as to provide the function of power regulation for the power grid 3, while taking into account both power regulation and the charging amount of the energy storage system 1 to avoid the excessive power of the energy storage unit 11 as much as possible; if the control unit 13 sets the adjustment ratio of the power regulation to decrease as the operating frequency increases, the efficiency of the energy storage system 1 can be improved.

[0129] In summary, this case provides an energy storage system and its operating method, which sets the adjustment ratio of the power regulation of the energy storage system according to the state of charge of the energy storage unit in the energy storage system, the operating frequency of the power grid, and the efficiency of the energy storage system, so that the energy storage unit supplies power to the power grid or charges from the power grid at a regulated ratio of the agreed capacity, thereby enabling the energy storage system to operate at a higher efficiency state.

[0130] It should be noted that the above are only preferred embodiments proposed for the purpose of illustrating this case. This case is not limited to the described embodiments, and the scope of this case is determined by the scope of the appended claims. And this case can be variously modified by those skilled in the art, but all are not outside the scope of protection as desired by the appended claims.

Claims

1. An energy storage system is used to be coupled to a power grid to provide power regulation with a maximum value of the agreed capacity to the power grid. When the operating frequency of the power grid is greater than or equal to a first frequency (fr1) and less than or equal to a second frequency (fr2), the regulation ratio of the power regulation of the energy storage system is greater than or equal to a first input boundary value (IL1) and less than or equal to a first output boundary value (OL1). When the operating frequency of the power grid is greater than or equal to a third frequency (fr3) and less than or equal to the first frequency (fr1), the regulation ratio of the power regulation of the energy storage system is greater than or equal to the first input boundary value (IL1) and less than or equal to a second output boundary value (OL2). When the operating frequency decreases from the first frequency (fr1) to the third frequency (fr3), a plurality of first upper limit values of the regulation ratio corresponding to the change in the operating frequency increase from the first output boundary value (OL1) to the second output boundary value (OL2), and a plurality of first lower limit values of the regulation ratio corresponding to the change in the operating frequency increase from the first input boundary value (IL1) to the second output boundary value (OL2). When the operating frequency of the power grid is greater than or equal to the second frequency (fr2) and less than or equal to a fourth frequency (fr4), the regulation ratio of the power regulation of the energy storage system is greater than or equal to a second input boundary value (IL2) and less than or equal to the first output boundary value (OL1). When the operating frequency increases from the second frequency (fr2) to the fourth frequency (fr4), a plurality of second upper limit values of the regulation ratio corresponding to the change in the operating frequency decrease from the first output boundary value (OL1) to the second input boundary value (IL2), and a plurality of second lower limit values of the regulation ratio corresponding to the change in the operating frequency decrease from the first input boundary value (IL1) to the second input boundary value (IL2). The energy storage system includes: An energy storage unit for storing and providing electrical energy. A measurement unit for measuring the operating frequency of the power grid. And A control unit for being coupled to the measurement unit and the energy storage unit to receive the operating frequency of the power grid measured by the measurement unit. Wherein, When the state of charge of the energy storage unit is greater than a first electric quantity, the energy storage unit is in a normal electric quantity state. When the state of charge of the energy storage unit is less than the first electric quantity, the energy storage unit is in a low electric quantity state. When the control unit sets the regulation ratio of the power regulation of the energy storage system to be greater than 0, the control unit sets the energy storage unit to supply power to the power grid at the regulation ratio of the agreed capacity. When the control unit sets the regulation ratio of the power regulation of the energy storage system to be less than 0, the control unit sets the energy storage unit to charge from the power grid at the regulation ratio of the agreed capacity. When the operating frequency of the power grid measured by the measurement unit is greater than or equal to the first frequency boundary value (f11) and less than or equal to the second frequency boundary value (f12), the control unit sets the adjustment ratio of the power adjustment to the first operation ratio (R11), and the first operation ratio (R11) is less than or equal to 0 and greater than or equal to the first input boundary value (IL1); The first frequency boundary value (f11) is less than the first frequency (fr1) and / or the second frequency boundary value (f12) is greater than the second frequency (fr2).

2. The energy storage system according to claim 1, wherein when the energy storage unit is in the normal power state, the first frequency boundary value (f11) is less than the first frequency (fr1) and the second frequency boundary value (f12) is greater than the second frequency (fr2).

3. The energy storage system according to claim 1, wherein when the energy storage unit is in the low power state, the first frequency boundary value (f21) is less than the first frequency (fr1).

4. The energy storage system according to claim 1, wherein when the state of charge of the energy storage unit is greater than the second power, the energy storage unit is in the high power state; when the energy storage unit is in the high power state, the second frequency boundary value (f32) is greater than the second frequency (fr2).

5. The energy storage system according to claim 1, further comprising an auxiliary power supply device, wherein the control unit sets the first operation ratio to be less than 0, so that the input electric energy received by the energy storage system from the power grid is greater than or equal to the auxiliary electric energy provided by the auxiliary power supply device.

6. The energy storage system according to claim 1, wherein when the operating frequency of the power grid measured by the measurement unit is greater than or equal to the third frequency (fr3) and less than or equal to the third frequency boundary values (f13, f23, f33), the control unit sets the adjustment ratio of the power adjustment to be less than or equal to the second output boundary value (OL2) and greater than or equal to the second operation ratios (R12, R22, R32); The third frequency boundary values (f13, f23, f33) are less than the first frequency boundary values (f11, f21, f31); The second operation ratios (R12, R22, R32) are greater than the first operation ratios (R11, R21, R31), and the second efficiency value of the energy storage system supplying power to the power grid at the second operation ratios (R12, R22, R32) is greater than the first efficiency value of the energy storage system supplying power to the power grid at the first operation ratios (R11, R21, R31) by an efficiency threshold.

7. The energy storage system according to claim 1, wherein when the state of charge of the energy storage unit is greater than the second electric quantity, the energy storage unit is in a high electric quantity state; when the energy storage unit is in the high electric quantity state and the operating frequency of the power grid measured by the measurement unit is greater than or equal to the third frequency (fr3) and less than or equal to the third frequency boundary value (f33), the control unit sets the adjustment ratio of the power adjustment to be less than or equal to the second output boundary value (OL2) and greater than or equal to the second operation ratio (R32); The third frequency boundary value (f33) is less than the first frequency boundary value (f31), and the first frequency boundary value (f31) is less than or equal to the second frequency boundary value (f32), which is the default power supply frequency of the power grid; The second operation ratio (R32) is greater than the first operation ratio (R31), and the second efficiency value of the energy storage system supplying power to the power grid at the second operation ratio (R32) is greater than the efficiency threshold than the first efficiency value of the energy storage system supplying power to the power grid at the first operation ratio (R31).

8. The energy storage system according to claim 1, when the operating frequency of the power grid measured by the measurement unit is greater than or equal to the third frequency boundary value (f16, f26, f34) and less than or equal to the fourth frequency (fr4), the control unit sets the adjustment ratio of the power adjustment to be less than or equal to the second operation ratio (R14, R24, R33) and greater than or equal to the second input boundary value (IL2); The third frequency boundary value (f16, f26, f34) is greater than the second frequency boundary value (f12, f22, f32); The second operation ratio (R14, R24, R33) is less than the first operation ratio (R11, R21, R31), and the second efficiency value of charging the energy storage unit from the power grid at the second operation ratio (R14, R24, R33) is greater than the efficiency threshold than the first efficiency value of charging the energy storage unit from the power grid at the first operation ratio (R11, R21, R31).

9. The energy storage system according to claim 1, wherein when the energy storage unit is in the low electric quantity state and the operating frequency of the power grid measured by the measurement unit is greater than or equal to the third frequency boundary value (f26) and less than or equal to the fourth frequency (fr4), the control unit sets the adjustment ratio of the power adjustment to be less than or equal to the second operation ratio (R24) and greater than or equal to the second input boundary value (IL2); The third frequency boundary value (f26) is greater than the second frequency boundary value (f22), and the second frequency boundary value (f22) is greater than or equal to the first frequency boundary value (f21), which is the default power supply frequency of the power grid; The second operation ratio (R24) is less than the first operation ratio (R21), and the second efficiency value of the power grid charging the energy storage unit from the power grid at the second operation ratio (R24) is greater than the first efficiency value of the power grid charging the energy storage unit from the power grid at the first operation ratio (R21) by an efficiency threshold value.

10. An operating method of an energy storage system, wherein the energy storage system is used to be coupled to a power grid to provide power regulation with a maximum value of a specified capacity to the power grid. When the operating frequency of the power grid is greater than or equal to a first frequency (fr1) and less than or equal to a second frequency (fr2), the regulation ratio of the power regulation of the energy storage system is greater than or equal to a first input boundary value (IL1) and less than or equal to a first output boundary value (OL1). When the operating frequency of the power grid is greater than or equal to a third frequency (fr3) and less than or equal to the first frequency (fr1), the regulation ratio of the power regulation of the energy storage system is greater than or equal to the first input boundary value (IL1) and less than or equal to a second output boundary value (OL2); when the operating frequency decreases from the first frequency (fr1) to the third frequency (fr3), a plurality of first upper limit values of the regulation ratio corresponding to the change in the operating frequency increase from the first output boundary value (OL1) to the second output boundary value (OL2) correspondingly, and a plurality of first lower limit values of the regulation ratio corresponding to the change in the operating frequency increase from the first input boundary value (IL1) to the second output boundary value (OL2) correspondingly. When the operating frequency of the power grid is greater than or equal to the second frequency (fr2) and less than or equal to a fourth frequency (fr4), the regulation ratio of the power regulation of the energy storage system is greater than or equal to a second input boundary value (IL2) and less than or equal to the first output boundary value (OL1); when the operating frequency increases from the second frequency (fr2) to the fourth frequency (fr4), a plurality of second upper limit values of the regulation ratio corresponding to the change in the operating frequency decrease from the first output boundary value (OL1) to the second input boundary value (IL2) correspondingly, and a plurality of second lower limit values of the regulation ratio corresponding to the change in the operating frequency decrease from the first input boundary value (IL1) to the second input boundary value (IL2) correspondingly. The energy storage system includes an energy storage unit, a measurement unit, and a control unit. The energy storage unit is used to store and supply electric energy. The measurement unit is used to measure the operating frequency of the power grid. The control unit is used to be coupled to the measurement unit and the energy storage unit, and is used to receive the operating frequency of the power grid measured by the measurement unit. When the state of charge of the energy storage unit is greater than the first electric quantity, the energy storage unit is in a normal electric quantity state. When the state of charge of the energy storage unit is less than the first electric quantity, the energy storage unit is in a low electric quantity state. When the control unit sets the adjustment ratio of the power adjustment of the energy storage system to be greater than 0, the control unit sets the energy storage unit to supply power to the power grid at the adjustment ratio of the agreed capacity. When the control unit sets the adjustment ratio of the power adjustment of the energy storage system to be less than 0, the control unit sets the energy storage unit to charge from the power grid at the adjustment ratio of the agreed capacity. The operation method includes: When the operating frequency of the power grid measured by the measurement unit is greater than or equal to the first frequency boundary value (f11) and less than or equal to the second frequency boundary value (f12), the control unit is set to set the adjustment ratio of the power adjustment to the first operation ratio (R11), where the first operation ratio (R11) is less than or equal to 0 and greater than or equal to the first input boundary value (IL1), and the first frequency boundary value (f11) is less than the first frequency (fr1) and / or the second frequency boundary value (f12) is greater than the second frequency (fr2).

11. The operation method according to claim 10, wherein when the energy storage unit is in the normal electric quantity state, the first frequency boundary value (f11) is less than the first frequency (fr1) and the second frequency boundary value (f12) is greater than the second frequency (fr2).

12. The operation method according to claim 10, wherein when the energy storage unit is in the low electric quantity state, the first frequency boundary value (f21) is less than the first frequency (fr1).

13. The operation method according to claim 10, wherein when the state of charge of the energy storage unit is greater than the second electric quantity, the energy storage unit is in a high electric quantity state. When the energy storage unit is in the high electric quantity state, the second frequency boundary value (f32) is greater than the second frequency (fr2).

14. The operation method according to claim 10, wherein the energy storage system further includes an auxiliary power supply device, and the operation method further includes: Setting the control unit to set the first operation ratio to be less than 0, so that the input electric energy received by the energy storage system from the power grid is greater than or equal to the auxiliary electric energy provided by the auxiliary power supply device.

15. The operation method according to claim 10 further includes: When the operating frequency of the power grid measured by the measurement unit is greater than or equal to the third frequency (fr3) and less than or equal to the third frequency boundary values (f13, f23, f33), the control unit is set to set the adjustment ratio of the power adjustment to be less than or equal to the second output boundary value (OL2) and greater than or equal to the second operation ratio (R12, R22, R32). Among them, The third frequency boundary values (f13, f23, f33) are less than the first frequency boundary values (f11, f21, f31). The second operation ratio (R12, R22, R32) is greater than the first operation ratio (R11, R21, R31), and the second efficiency value of the energy storage system supplying power to the power grid at the second operation ratio (R12, R22, R32) is greater than the efficiency threshold compared to the first efficiency value of the energy storage system supplying power to the power grid at the first operation ratio (R11, R21, R31).

16. The operating method according to claim 10, wherein when the state of charge of the energy storage unit is greater than the second electric quantity, the energy storage unit is in a high state of charge, and the operating method further includes: When the energy storage unit is in the high state of charge and the operating frequency of the power grid measured by the measurement unit is greater than or equal to the third frequency (fr3) and less than or equal to the third frequency boundary value (f33), the control unit is set to set the adjustment ratio of the power adjustment to be less than or equal to the second output boundary value (OL2) and greater than or equal to the second operation ratio (R32). Wherein the third frequency boundary value (f33) is less than the first frequency boundary value (f31), and the first frequency boundary value (f31) is less than or equal to the default power supply frequency of the second frequency boundary value (f32) of the power grid. The second operation ratio (R32) is greater than the first operation ratio (R31), and the second efficiency value of the energy storage system supplying power to the power grid at the second operation ratio (R32) is greater than the efficiency threshold compared to the first efficiency value of the energy storage system supplying power to the power grid at the first operation ratio (R31).

17. The operating method according to claim 10 further includes: When the operating frequency of the power grid measured by the measurement unit is greater than or equal to the third frequency boundary values (f16, f26, f34) and less than or equal to the fourth frequency (fr4), the control unit is set to set the adjustment ratio of the power adjustment to be less than or equal to the second operation ratio (R14, R24, R33) and greater than or equal to the second input boundary value (IL2). Among them, The third frequency boundary values (f16, f26, f34) are greater than the second frequency boundary values (f12, f22, f32). The second operation ratio (R14, R24, R33) is less than the first operation ratio (R11, R21, R31), and the second efficiency value of charging the energy storage unit from the power grid at the second operation ratio (R14, R24, R33) is greater than the first efficiency value of charging the energy storage unit from the power grid at the first operation ratio (R11, R21, R31) by an efficiency threshold value.

18. The operation method according to claim 10 further includes: When the energy storage unit is in the low power state and the operation frequency of the power grid measured by the measurement unit is greater than or equal to a third frequency boundary value (f26) and less than or equal to the fourth frequency (fr4), the control unit sets the adjustment ratio of the power adjustment to be less than or equal to a second operation ratio (R24) and greater than or equal to the second input boundary value (IL2); wherein the third frequency boundary value (f26) is greater than the second frequency boundary value (f22), and the second frequency boundary value (f22) is greater than or equal to the default power supply frequency of the first frequency boundary value (f21) of the power grid; and The second operation ratio (R24) is less than the first operation ratio (R21), and the second efficiency value of charging the energy storage unit from the power grid at the second operation ratio (R24) is greater than the first efficiency value of charging the energy storage unit from the power grid at the first operation ratio (R21) by an efficiency threshold value.

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