A coordinated control method and system for improving the utilization efficiency of energy storage

Abstract

The present invention belongs to the technical field of energy management and control, and discloses a coordinated control method and system for improving the utilization efficiency of energy storage. It includes a flywheel energy storage system, an inverter, a DC / AC converter, and an electrochemical energy storage system, wherein: the flywheel energy storage system is connected to the input interface of the inverter through a DC bus; the output interface of the inverter is connected to an external AC power grid through three-phase wires; the electrochemical energy storage system is connected to the DC bus connecting the flywheel energy storage system and the inverter through a wire; the DC end of the DC / AC converter is connected to the input interface of the inverter; the AC end of the DC / AC converter is connected to the output interface of the inverter. The method of the present invention is simple, the system is concise, and at the same time, the power and energy constraints of the flywheel energy storage and the electrochemical energy storage are considered, which has a positive effect on improving the response accuracy and efficiency of the hybrid energy storage system.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy management and control, and particularly relates to a coordinated control method and system for improving the utilization efficiency of energy storage. Background Art

[0002] With the gradual deepening of China's industrialization process, the electricity consumption is increasing day by day and the electricity demand is becoming more diverse. The energy storage system, with its advantage of flexible energy regulation, has become an increasingly important role in the power grid field.

[0003] At present, there are various types of energy storage with different characteristics. Among them, electrochemical energy storage has become the first choice for power grid energy storage due to its stable power output, long charge and discharge time, and low construction cost. However, when electrochemical energy storage is applied in scenarios with relatively high charge and discharge frequencies, there will be problems such as inaccurate SOC correction and insufficient response rate. To solve these problems, existing research has considered using supercapacitors in cooperation with electrochemical energy storage to jointly respond to power output. However, supercapacitors have problems such as high cost, large floor area, and short lifespan. At present, although a method of using flywheels and electrochemical energy storage for time-scale matching has been proposed, which can effectively improve the response accuracy and efficiency of electrochemical energy storage, there is currently no power coordination control method for such a hybrid energy storage system. Summary of the Invention

[0004] The purpose of the present invention is to provide a coordinated control method and system for improving the utilization efficiency of energy storage to solve the problems in the prior art.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] A coordinated control system for improving the utilization efficiency of energy storage includes a flywheel energy storage system, an inverter, a DC / AC converter, and an electrochemical energy storage system, wherein:

[0007] The flywheel energy storage system is connected to the input interface of the inverter through a DC bus;

[0008] The output interface of the inverter is connected to the external AC power grid through three-phase wires;

[0009] The electrochemical energy storage system is connected to the DC bus between the flywheel energy storage system and the inverter through a wire;

[0010] The DC end of the DC / AC converter is connected to the input interface of the inverter; the AC end of the DC / AC converter is connected to the output interface of the inverter.

[0011] Further, it further includes a hybrid energy storage system, and the hybrid energy storage system includes a hybrid energy storage instruction generation module, a hybrid energy storage power detection module, and a system frequency detection module, where:

[0012] The hybrid energy storage power detection module is connected to the first input end of the hybrid energy storage instruction generation module;

[0013] The system frequency detection module is connected to the second input end of the hybrid energy storage instruction generation module;

[0014] The first output end of the hybrid energy storage instruction generation module is connected to the control end of the AC / DC converter;

[0015] The second output end of the hybrid energy storage instruction generation module is connected to the control end of the DC / DC converter.

[0016] Further, the hybrid energy storage instruction generation module includes a power and frequency measurement quantity receiving and storing module, a hybrid energy storage instruction calculation module, and a flywheel and electrochemical energy storage instruction generation module, where:

[0017] The power and frequency measurement quantity receiving and storing module is configured to receive the frequency measurement quantity input by the system frequency detection module and the power input by the hybrid energy storage power detection module, and transmit them to the hybrid energy storage instruction calculation module;

[0018] The hybrid energy storage instruction calculation module is configured to calculate according to the input frequency measurement quantity and power, obtain the power instruction value of the flywheel energy storage and the power instruction value of the electrochemical energy storage, and transmit them to the flywheel and electrochemical energy storage instruction generation module;

[0019] The flywheel and electrochemical energy storage instruction generation module is configured to output the obtained power instruction value of the flywheel energy storage to the AC / DC converter, and output the power instruction value of the electrochemical energy storage to the DC / DC converter.

[0020] Further, the hybrid energy storage power detection module includes a raw electrical quantity measurement sensor module, an electrical quantity signal filtering and calculation module, and a power measurement quantity generation module, where:

[0021] The raw electrical quantity measurement sensor module is configured to measure the electrical signal of the AC power grid and transmit it to the electrical quantity signal filtering and calculation module;

[0022] The electrical quantity signal filtering and calculation module is configured to filter and calculate the received electrical signal and then transmit it to the power measurement quantity generation module;

[0023] The power measurement quantity generation module performs analog-to-digital and digital-to-analog signal conversions based on the power values obtained through filtering and calculation by the electrical quantity signal filtering and calculation module, and transmits the converted power values to the hybrid energy storage instruction generation module.

[0024] Further, the system frequency detection module includes an original frequency quantity measurement sensor module, a frequency quantity filtering link module, and a frequency measurement quantity generation module, where: the original frequency quantity measurement sensor module is used to detect the original frequencies of the flywheel energy storage and the electrochemical energy storage, and transmit the measured quantities of the detected original frequencies to the frequency quantity filtering link module;

[0025] The frequency quantity filtering link module is used to filter the measured quantities of the original frequencies and transmit them to the frequency measurement quantity generation module;

[0026] The frequency measurement quantity generation module is used to generate frequency measurement quantities based on the filtered measured quantities of the original frequencies, and transmit the generated frequency measurement quantities to the hybrid energy storage instruction generation module.

[0027] Further, the flywheel energy storage system includes a flywheel, a permanent magnet synchronous motor, and an AC / DC converter, where:

[0028] The flywheel is fixedly connected to the motor shaft of the permanent magnet synchronous motor through a flywheel shaft;

[0029] The AC side of the AC / DC converter is connected to the permanent magnet synchronous motor, and the DC side is connected to the input interface of the inverter; the control end of the AC / DC converter is connected to the hybrid energy storage instruction generation module.

[0030] Further, the electrochemical energy storage system includes a DC / DC converter and a storage battery, where:

[0031] One end of the DC / DC converter is connected to the DC bus through a wire;

[0032] The storage battery is connected to the other end of the DC / DC converter.

[0033] A coordinated control method for improving the energy storage utilization efficiency, characterized by including:

[0034] S1: Invert the electric energy of the external AC power grid through three-phase wires connected to the inverter;

[0035] S2: Transmit the inverted electric energy to the flywheel energy storage system through the DC bus for preliminary storage;

[0036] S3: Connect an electrochemical energy storage system to the DC bus to store the electric energy of the external AC power grid again;

[0037] S4: Connect the DC / AC converter in parallel to the inverter to convert the electric energy transmitted to the electro-chemical energy storage system;

[0038] S5: Perform hybrid energy storage from the external power grid on the flywheel energy storage system and the electro-chemical energy storage system respectively.

[0039] Further, the method of hybrid energy storage in S5 is as follows:

[0040] Construct a flywheel 11 system and an electro-chemical energy storage system 4; continuously detect the power command signal P* through the hybrid energy storage command generation module 7 and give a reference initial frequency f0;

[0041] Filter and decompose the power command signal according to the reference initial frequency. Let n = 0 to obtain Perform energy constraint check on the initial frequency after filtering and decomposition. If the system triggers the constraint check condition, perform the critical frequency adjustment operation and turn to the operation of filtering and decomposing the power command signal according to the initial frequency; otherwise, perform power constraint check on the power after energy constraint check. If the constraint check triggers the power constraint check condition, adjust the critical frequency of the flywheel energy storage and the electro-chemical energy storage system. If it does not trigger, calculate the reference power of the flywheel energy storage and the electro-chemical energy storage.

[0042] Allocate reference power to the hybrid energy storage system of the flywheel energy storage and the electro-chemical energy storage. The calculation method of the reference power is as follows:

[0043]

[0044]

[0045] where: P FW * refers to the power command value of the flywheel energy storage, P B * refers to the power command value of the electro-chemical energy storage; refers to the power signal component below the frequency fn, refers to the power signal component above the frequency fn.

[0046] Further, the constraint check conditions are:

[0047]

[0048] Or

[0049]

[0050] where: In the constraint check conditions, let f n+1 = f n+Δf, n = n + 1;

[0051] SOC FW refers to the current state of charge of the flywheel energy storage, SOC FWmax refers to the maximum state of charge of the flywheel energy storage, SOC FWmin refers to the maximum state of charge of the flywheel energy storage;

[0052] The power constraint verification condition is:

[0053]

[0054] And

[0055]

[0056] Wherein: f in the power constraint verification condition n+1 and f n are consistent with the constraint verification condition, which is: Let f n+1 = f n +Δf, n = n + 1.

[0057] Compared with the prior art, the present invention has at least the following beneficial effects:

[0058] 1. Through the flywheel energy storage system, inverter, second power converter and electrochemical energy storage system, using the flywheel-electrochemical hybrid energy storage system, the control module receives the power command, sets the initial power frequency division critical frequency, and decomposes the power according to the critical frequency; conducts the state of charge boundary condition verification, and adjusts the critical frequency according to the verification result; conducts the output power boundary condition verification, and adjusts the critical frequency according to the verification result; allocates the actual power reference signal for the flywheel and the electrochemical energy storage components, records the response and uploads the response result. The method is simple, and at the same time, through the power and energy constraints of the flywheel energy storage and the electrochemical energy storage, it has good reference value in improving the response accuracy and efficiency of the hybrid energy storage system.

[0059] 2. Through the structure of the flywheel, the energy and inertia outside the working stroke of the motor are stored, reducing the work and energy loss of the motor.

[0060] 3. Through the energy constraint verification of the energy storage system, the problem that the flywheel energy storage cannot respond to high-frequency power fluctuations due to overcharging or over-discharging, resulting in the SOC being lower or higher than the critical value, is avoided. And when it is found that the energy constraint is not met, the critical frequency can be adjusted in time to reduce the charge and discharge pressure of the flywheel energy storage.

[0061] 4. Through the power constraint verification of the energy storage system, the problem that the utilization rate of the electrochemical energy storage is too low due to too low setting of the critical frequency is avoided, which can effectively improve the utilization efficiency of the electrochemical energy storage without affecting its service life. Description of the Drawings

[0062] The accompanying drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments and descriptions thereof of the invention are used to explain the invention and do not unduly limit the invention. In the drawings:

[0063] Figure 1 It is the system structure diagram of the flywheel - electrochemical hybrid energy storage control system of a coordinated control system for improving the energy storage utilization efficiency of the present invention;

[0064] Figure 2 It is the flowchart of a coordinated control method for improving the energy storage utilization efficiency of the present invention; Hybrid energy storage instruction generation module;

[0065] Figure 3 It is the effect simulation diagram of the coordinated control system for improving the energy storage utilization efficiency of the present invention in dividing - frequency response to the fluctuation of the power command reference value;

[0066] Figure 4 It is the effect simulation diagram of the power decomposition of the coordinated control system for improving the energy storage utilization efficiency of the present invention participating in system frequency modulation;

[0067] Figure 5 It is the schematic flow diagram of a coordinated control method for improving the energy storage utilization efficiency of the present invention;

[0068] Figure 6 It is the flowchart of a coordinated control method for improving the energy storage utilization efficiency of the present invention;

[0069] 1. Flywheel energy storage system; 2. DC bus; 3. Inverter; 4. Electrochemical energy storage system; 5. DC / AC converter; 6. AC power grid; 11. Flywheel; 12. Permanent magnet synchronous motor; 13. AC / DC converter; 41. DC / DC converter; 42. Battery; 7. Hybrid energy storage instruction generation module; 8. Hybrid energy storage power detection module; 9. System frequency detection module. Specific Embodiments

[0070] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0071] The following detailed descriptions are all exemplary descriptions, aiming to provide a further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments and are not intended to limit the exemplary embodiments of the present invention.

[0072] Embodiment 1:

[0073] As Figure 1 shown, a coordinated control system for improving the energy utilization efficiency of energy storage includes a flywheel energy storage system 1, an inverter 3, a DC / AC converter 5, and an electrochemical energy storage system 4, where: The flywheel energy storage system 1 is connected to the input interface of the inverter 3 through a DC bus 2; the output interface of the inverter 3 is connected to an external AC power grid 6 through three-phase wires; the electrochemical energy storage system 4 is connected to the DC bus 2 between the flywheel energy storage system 1 and the inverter 3 through a wire; the DC end of the DC / AC converter 5 is connected to the input interface of the inverter 3; the AC end of the DC / AC converter 5 is connected to the output interface of the inverter 3.

[0074] Specifically, two wires at one end of the DC / AC converter 5 are respectively connected to the neutral wire and the live wire of the electrochemical energy storage system 4; the other end is respectively connected to the neutral wire, the live wire, and the ground wire of the three-phase circuit where the inverter 3 is connected to the AC power grid 6.

[0075] Specifically, AC represents alternating current; DC represents direct current; AC / DC represents an AC / DC power converter, which means the power supply specification is AC input and DC output, and it belongs to one of the classifications of switching power supplies.

[0076] The flywheel-electrochemical hybrid energy storage control system control module composed of the flywheel energy storage system 1 and the electrochemical energy storage system 4 receives a power command, sets the initial power frequency division critical frequency, decomposes the power according to the critical frequency; conducts a state of charge boundary condition check, and adjusts the critical frequency according to the check result; conducts an output power boundary condition check, and adjusts the critical frequency according to the check result; allocates actual power reference signals to the flywheel and the electrochemical energy storage components, records the response situation and uploads the response result. The structure is simple, and it has good reference value in improving the response accuracy and efficiency of the hybrid energy storage system through the power and energy constraints of the flywheel energy storage and the electrochemical energy storage.

[0077] Further specifically, the flywheel energy storage system 1 includes a flywheel 11, a motor 12, and an AC / DC converter 13, where: The flywheel 11 is fixedly connected to the motor shaft of the motor 12 through a flywheel shaft; the AC end of the AC / DC converter 13 is connected to the motor 12, and the DC end is connected to the input interface of the inverter 3; the control end of the AC / DC converter 13 is connected to the hybrid energy storage command generation module 7.

[0078] Further specifically, the electrochemical energy storage system 4 includes a DC / DC converter 41 and a storage battery 42, where: One end of the DC / DC converter 41 is connected to the DC bus 2 through a wire; the storage battery 42 is connected to the other end of the DC / DC converter 41.

[0079] Preferably, the motor is a permanent magnet synchronous motor 12.

[0080] Further, the DC / DC converter 41 means that the power supply specification is DC input and DC output.

[0081] More specifically, in this embodiment, a hybrid energy storage system composed of a flywheel energy storage with a capacity of 1 MW, 5 MJ, and a maximum full discharge time of 5 s and a battery with a capacity of 2 MW, 1 MWh, and a maximum full discharge time of 30 min is selected. Here, 1 MW represents 1 megawatt, which means 1 megawatt when the energy storage reaches its maximum output power; 5 MJ represents 5 megajoules, which means the maximum energy that the energy storage can accommodate is 5 megajoules. Similarly, 2 MW represents 2 megawatts, which means 2 megawatts when the energy storage reaches its maximum output power; 1 MWh represents 1 megawatt-hour, which means the maximum energy that the energy storage can accommodate is 1 megawatt-hour.

[0082] Further, as Figure 2 shown, the hybrid energy storage system includes a hybrid energy storage instruction generation module 7, a hybrid energy storage power detection module 8, and a system frequency detection module 9, where: the hybrid energy storage power detection module 8 is connected to the first input end of the hybrid energy storage instruction generation module 7; the system frequency detection module 9 is connected to the second input end of the hybrid energy storage instruction generation module 7; the first output end of the hybrid energy storage instruction generation module 7 is connected to the control end of the AC / DC converter 13; the second output end of the hybrid energy storage instruction generation module 7 is connected to the control end of the DC / DC converter 41.

[0083] Specifically, the hybrid energy storage instruction generation module 7 includes a power and frequency measurement quantity receiving and storing module, a hybrid energy storage instruction calculation module, and a flywheel and electrochemical energy storage instruction generation module, where: the power and frequency measurement quantity receiving and storing module is used to receive the frequency measurement quantity input by the system frequency detection module 9 and the power input by the hybrid energy storage power detection module 8, and transmit them to the hybrid energy storage instruction calculation module; the hybrid energy storage instruction calculation module is used to calculate based on the input frequency measurement quantity and power to obtain the power instruction value of the flywheel energy storage and the power instruction value of the electrochemical energy storage, and transmit them to the flywheel and electrochemical energy storage instruction generation module; the flywheel and electrochemical energy storage instruction generation module is used to output the obtained power instruction value of the flywheel energy storage to the AC / DC converter 13 and output the power instruction value of the electrochemical energy storage to the DC / DC converter 41.

[0084] Further, the hybrid energy storage power detection module 8 includes an original electrical quantity measurement sensor module, an electrical quantity signal filtering and calculation module, and a power measurement quantity generation module, where: the original electrical quantity measurement sensor module is used to measure the electrical signal of the AC power grid 6 and transmit it to the electrical quantity signal filtering and calculation module; the electrical quantity signal filtering and calculation module is used to filter and calculate the received electrical signal and then transmit it to the power measurement quantity generation module; the power measurement quantity generation module performs analog-to-digital and digital-to-analog signal conversions on the power value obtained by filtering and calculating the electrical quantity signal, and transmits the converted power value to the hybrid energy storage instruction generation module 7.

[0085] Further, the system frequency detection module 9 includes an original frequency quantity measurement sensor module, a frequency quantity filtering link module, and a frequency measurement quantity generation module, where: the original frequency quantity measurement sensor module is used to detect the original frequencies of the flywheel energy storage and the electrochemical energy storage, and transmit the measured quantity of the detected original frequencies to the frequency quantity filtering link module; the frequency quantity filtering link module is used to filter the measured quantity of the original frequency and then transmit it to the frequency measurement quantity generation module; the frequency measurement quantity generation module is used to generate a frequency measurement quantity based on the filtered measured quantity of the original frequency, and transmit the generated frequency measurement quantity to the hybrid energy storage instruction generation module 7.

[0086] Combined with Figure 3 the frequency division response of Figure 4 and taking the system frequency modulation of

[0087] For example, as Figure 3 shown, the critical frequency of the flywheel energy storage system 1 is set to 2 Hz. Figure 2 Three power fluctuation curves are shown in

[0088] where, from top to bottom, they respectively represent: the load fluctuation / system total power output curve, the electrochemical energy storage output curve, and the flywheel output curve. It can be seen from the three comparison curves that the power of the flywheel output curve is significantly lower than the power values of the system total power fluctuation output and the electrochemical energy storage output curve. Thus, it can be concluded that through the structure of the flywheel, the energy and inertia outside the motor working stroke are stored, reducing the work and energy loss of the motor.

[0089] Further specifically, as Figure 4 shown, the critical frequency of the flywheel energy storage system 1 is set to 2 Hz. Figure 4 Two power fluctuation curves are shown in Figure 4The arc in the upper-middle part similar to an irregular sine curve represents the output power of the electrochemical energy storage system 4, and the curve composed of a straight line and an arc in the lower part represents the output power of the flywheel energy storage. It can be seen that the system with the output power of the flywheel energy storage consumes less energy, so the energy utilization rate is higher and more energy is stored.

[0090] Specifically, the hybrid energy storage system participates in the frequency modulation requirements with large frequency fluctuations, performs frequency division processing on the frequency fluctuations of the system, and the electrochemical energy storage responds to low-frequency fluctuations, while the flywheel energy storage responds to high-frequency fluctuations, which can effectively reduce the charge and discharge times of the electrochemical energy storage and at the same time suppress the frequent fluctuations of the frequency.

[0091] Embodiment 2:

[0092] As Figure 5 shown, a coordinated control method for improving the energy storage utilization efficiency includes:

[0093] S1: Invert the electric energy of the external AC power grid 6 through a three-phase wire connected to the inverter 3;

[0094] S2: Transmit the inverted electric energy to the flywheel energy storage system 1 through the DC bus 2 for preliminary storage;

[0095] S3: Connect the electrochemical energy storage system 4 to the DC bus 2 to store the electric energy of the external AC power grid 6 again;

[0096] S4: Connect a DC / AC converter 5 in parallel to the inverter 3 to convert the electric energy transmitted to the electrochemical energy storage system 4;

[0097] S5: Perform hybrid energy storage of the external power grid for the flywheel energy storage system 1 and the electrochemical energy storage system 2 respectively.

[0098] Further, as Figure 6 shown, the method of hybrid energy storage in S5 is: construct a flywheel 11 system and an electrochemical energy storage system 4; continuously detect the power command signal P* through the hybrid energy storage command generation module 7 and give the reference initial frequency f0;

[0099] Filter and decompose the power command signal according to the reference initial frequency, let n = 0, and obtain Perform energy constraint verification on the filtered and decomposed initial frequency. If the system triggers the constraint verification condition, perform the critical frequency adjustment operation and turn to the operation of filtering and decomposing the power command signal according to the initial frequency; otherwise, perform power constraint verification on the power after energy constraint verification. If the constraint verification triggers the power constraint verification condition, adjust the critical frequency of the flywheel energy storage and the electrochemical energy storage system. If it does not trigger, calculate the reference power of the flywheel energy storage and the electrochemical energy storage;

[0100] The reference power for the hybrid energy storage system of flywheel energy storage and electrochemical energy storage is allocated, and the calculation method of the reference power is as follows:

[0101]

[0102]

[0103] Where: P FW * refers to the power command value of the flywheel energy storage, and P B * refers to the power command value of the electrochemical energy storage; refers to the power signal component below the frequency fn, refers to the power signal component above the frequency fn.

[0104] Furthermore, the constraint checking conditions are:

[0105]

[0106] Or

[0107]

[0108] Where: in the constraint checking conditions, let f n+1 = f n +Δf, n = n + 1;

[0109] SOC FW refers to the current state of charge of the flywheel energy storage, and SOC FWmax refers to the maximum state of charge of the flywheel energy storage, and SOC FWmin refers to the maximum state of charge of the flywheel energy storage.

[0110] Where: the power constraint checking conditions are:

[0111]

[0112] And

[0113]

[0114] Where: f n+1 and f n in the power constraint checking conditions are consistent with the conditions of the constraint checking, which are: let f n+1 = f n +Δf, n = n + 1.

[0115] As is known by common technical knowledge, the present invention can be implemented by other embodiments that do not depart from its spiritual essence or essential features. Therefore, the above-disclosed embodiments are illustrative in all aspects and not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the specific implementation manners of the present invention, and any modification or equivalent substitution that does not depart from the spirit and scope of the present invention should be covered within the scope of the protection of the claims of the present invention.

Claims

1. A coordinated control system for improving the utilization efficiency of energy storage, characterized in that, It includes a flywheel energy storage system (1), an inverter (3), a DC / AC converter (5), and an electrochemical energy storage system (4), where: The flywheel energy storage system (1) is connected to the input interface of the inverter (3) through a DC bus (2); The output interface of the inverter (3) is connected to an external AC power grid (6) through three-phase wires; The electrochemical energy storage system (4) is connected to the DC bus (2) between the flywheel energy storage system (1) and the inverter (3) through a wire; The DC end of the DC / AC converter (5) is connected to the input interface of the inverter (3); the AC end of the DC / AC converter (5) is connected to the output interface of the inverter (3); A coordinated control system for improving the energy storage utilization efficiency is used to perform hybrid energy storage of the external power grid on the flywheel energy storage system (1) and the electrochemical energy storage system (4) respectively. The method of hybrid energy storage is as follows: Construct a flywheel (11) system and an electrochemical energy storage system (4); continuously detect the power command signal P* through the hybrid energy storage command generation module (7) and give a reference initial frequency f 0; Filter and decompose the power command signal according to the reference initial frequency. Let n = 0, and obtain = )+ ); Conduct an energy constraint check on the initial frequency after filtering and decomposition. If the system triggers the constraint check condition, perform the operation of adjusting the critical frequency and turn to the operation of filtering and decomposing the power command signal according to the initial frequency; otherwise, conduct a power constraint check on the power after the energy constraint check. If the constraint check triggers the power constraint check condition, adjust the critical frequency of the flywheel energy storage and the electrochemical energy storage system. If it does not trigger, calculate the reference power of the flywheel energy storage and the electrochemical energy storage system; Allocate reference power to the flywheel energy storage and electrochemical energy storage for the hybrid energy storage system. The calculation method of the reference power is as follows: ； Wherein: P FW * refers to the power command value of the flywheel energy storage, P B * refers to the power command value of the electrochemical energy storage; ) refers to the power signal component below the frequency fn, ) refers to the power signal component above the frequency fn; The constraint checking conditions are as follows: Or Wherein: in the constraint checking condition, let = + , n = n + 1; SOC FW refers to the current state of charge of the flywheel energy storage, SOC FWmax refers to the maximum state of charge of the flywheel energy storage, SOC FWmin refers to the maximum state of charge of the flywheel energy storage; The power constraint verification condition is as follows: And Among them: In the power constraint verification condition, and are consistent with the constraint verification condition, which is: Let = + , n = n + 1.

2. The coordinated control system for improving the energy storage utilization efficiency according to claim 1, wherein It further includes a hybrid energy storage system. The hybrid energy storage system includes a hybrid energy storage command generation module (7), a hybrid energy storage power detection module (8), and a system frequency detection module (9), where: The hybrid energy storage power detection module (8) is connected to the first input end of the hybrid energy storage command generation module (7); The system frequency detection module (9) is connected to the second input end of the hybrid energy storage command generation module (7); The first output end of the hybrid energy storage command generation module (7) is connected to the control end of the AC / DC converter (13); The second output end of the hybrid energy storage command generation module (7) is connected to the control end of the DC / DC converter (41).

3. The coordinated control system for improving the energy storage utilization efficiency according to claim 2, wherein, The hybrid energy storage command generation module (7) includes a power and frequency measurement quantity receiving and storing module, a hybrid energy storage command calculation module, and a flywheel and electrochemical energy storage command generation module, where: The power and frequency measurement quantity receiving and storing module is used to receive the frequency measurement quantity input by the system frequency detection module (9) and the power input by the hybrid energy storage power detection module (8), and transmit them to the hybrid energy storage command calculation module; The hybrid energy storage command calculation module is used to calculate based on the input frequency measurement quantity and power, obtain the power command value of the flywheel energy storage and the power command value of the electrochemical energy storage, and transmit them to the flywheel and electrochemical energy storage command generation module; The flywheel and electrochemical energy storage command generation module is used to output the obtained power command value of the flywheel energy storage to the AC / DC converter (13), and output the power command value of the electrochemical energy storage to the DC / DC converter (41).

4. The coordinated control system for improving the energy storage utilization efficiency according to claim 2, wherein The hybrid energy storage power detection module (8) includes an original electrical quantity measurement sensor module, an electrical quantity signal filtering and calculation module, and a power measurement quantity generation module, where: The original electrical quantity measurement sensor module is used to measure the electrical signal of the AC power grid and transmit it to the electrical quantity signal filtering and calculation module; The electrical quantity signal filtering and calculation module is used to filter and calculate the received electrical signal and then transmit it to the power measurement quantity generation module; The power measurement quantity generation module performs analog-to-digital and digital-to-analog signal conversions on the power value obtained by filtering and calculating through the electrical quantity signal filtering and calculation module, and transmits the converted power value to the hybrid energy storage instruction generation module (7).

5. The coordinated control system for improving the energy storage utilization efficiency according to claim 2, characterized in that, The system frequency detection module (9) includes a raw frequency quantity measurement sensor module, a frequency quantity filtering link module, and a frequency measurement quantity generation module, where: the raw frequency quantity measurement sensor module is used to detect the raw frequency of the flywheel energy storage and the electrochemical energy storage, and transmit the measurement quantity of the detected raw frequency to the frequency quantity filtering link module; The frequency quantity filtering link module is used to filter the measurement quantity of the raw frequency and then transmit it to the frequency measurement quantity generation module; The frequency measurement quantity generation module is used to generate a frequency measurement quantity based on the filtered measurement quantity of the raw frequency, and transmit the generated frequency measurement quantity to the hybrid energy storage instruction generation module (7).

6. The coordinated control system for improving the energy storage utilization efficiency according to claim 2, characterized in that, The flywheel energy storage system (1) includes a flywheel (11), a permanent magnet synchronous motor (12), and an AC / DC converter (13), where: The flywheel (11) is fixedly connected to the motor shaft of the permanent magnet synchronous motor (12) through a flywheel shaft; The AC terminal of the AC / DC converter (13) is connected to the permanent magnet synchronous motor (12), and the DC terminal is connected to the input interface of the inverter (3); the control terminal of the AC / DC converter (13) is connected to the hybrid energy storage instruction generation module (7).

7. The coordinated control system for improving the energy storage utilization efficiency according to claim 1, characterized in that, The electrochemical energy storage system (4) includes a DC / DC converter (41) and a storage battery (42), where: One end of the DC / DC converter (41) is connected to the DC bus (2) through a wire; The storage battery (42) is connected to the other end of the DC / DC converter (41).

8. A coordinated control method for improving the utilization efficiency of energy storage, characterized in that, It includes: S1: Connect the electric energy of the external AC power grid (6) to the inverter (3) through three-phase wires for inversion; S2: Transmit the inverted electric energy to the flywheel energy storage system (1) through the DC bus (2) for preliminary storage; S3: Connect the electrochemical energy storage system (4) to the DC bus (2) to store the electric energy of the external AC power grid (6) again; S4: Connect a DC / AC converter (5) in parallel to the inverter (3) to convert the electric energy transmitted to the electrochemical energy storage system (4); S5: Perform hybrid energy storage of the external power grid on the flywheel energy storage system (1) and the electrochemical energy storage system (4) respectively; The method of hybrid energy storage is: Construct a flywheel (11) system and an electrochemical energy storage system (4); continuously detect the power command signal P* through the hybrid energy storage command generation module (7) and give the reference initial frequency f 0; Filter and decompose the power command signal according to the reference initial frequency. Let n = 0, and obtain = )+ ); Conduct an energy constraint check on the initial frequency after filtering and decomposition. If the system triggers the constraint check condition, perform the critical frequency adjustment operation and turn to the operation of filtering and decomposing the power command signal according to the initial frequency; otherwise, conduct a power constraint check on the power after the energy constraint check. If the constraint check triggers the power constraint check condition, adjust the critical frequency of the flywheel energy storage and the electrochemical energy storage system. If it does not trigger, calculate the reference power of the flywheel energy storage and the electrochemical energy storage system; Allocate reference power to the flywheel energy storage and the electrochemical energy storage in the hybrid energy storage system. The calculation method of the reference power is: ； Wherein: P FW * refers to the power command value of the flywheel energy storage, P B * refers to the power command value of the electrochemical energy storage; ) refers to the power signal component below the frequency fn, ) refers to the power signal component above the frequency fn; The constraint checking conditions are as follows: Or Wherein: in the constraint checking condition, let = + , n = n + 1; SOC FW refers to the current state of charge of the flywheel energy storage, SOC FWmax refers to the maximum state of charge of the flywheel energy storage, SOC FWmin refers to the maximum state of charge of the flywheel energy storage; The power constraint verification condition is as follows: And Among them: In the power constraint verification condition, and are consistent with the constraint verification condition, which is: Let = + , n = n + 1.

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