Energy storage system and control method thereof

Abstract

The invention discloses an energy storage system and a control method thereof. The energy storage system comprises an energy storage loop in which energy storage fluid circulates and a first heat exchange loop in which heat exchange fluid circulates. A first energy conversion device, a second energy conversion device, a first flow dividing assembly, a first-stage pressure storage tank, a second-stage pressure storage tank and a third-stage pressure storage tank which are communicated are arranged in the energy storage loop, and the energy storage system further comprises at least one heat exchange device. According to the embodiment of the invention, the high-pressure energy storage fluid in the third-stage pressure storage tank is divided into the first stream and the second stream through the first shunting assembly, the first stream is used for acting to supply power to a user power utilization system, and the second stream which does not act is recycled through the second-stage pressure storage tank; and the ratio of the first stream to the second stream is adjusted according to the demand of a power utilization system of a user, so that the energy utilization efficiency in the energy storage system is improved.

Description

Technical Field

[0001] The present application relates to the field of energy technology, and in particular to an energy storage system and a control method thereof. Background Art

[0002] Since the power generation of renewable energy is irregular and difficult to match with the peak and valley periods of power demand of the user's power system, in order to store the excess energy of renewable energy, there are some energy storage systems in the related technology, which use air, carbon dioxide and other fluids as energy storage media, and realize energy storage and release through changes in the pressure of the energy storage medium. However, when adapting to the peak and valley periods of power demand of the user's power system, the compressed gas energy storage system in the related technology needs to adjust the flow rate of the tank output to adjust the amount of released energy. However, this will cause the output of the energy storage system to be unstable, so that the performance of key components such as compressors and turbines will deteriorate and their lifespan will be reduced, reducing the energy utilization efficiency and service life of the energy storage system. Summary of the invention

[0003] The purpose of the present application is to propose an energy storage system and a control method thereof in view of the deficiencies of the above-mentioned prior art, so as to at least solve the deficiencies of the above-mentioned prior art. This purpose is achieved through the following technical solutions.

[0004] The embodiment of the present application provides an energy storage system, the energy storage system comprising an energy storage circuit in which an energy storage fluid flows and a first heat exchange circuit in which a heat exchange fluid flows;

[0005] The energy storage circuit is provided with a first energy conversion device, a second energy conversion device, a first flow dividing component, a first-stage pressure storage tank, a second-stage pressure storage tank and a third-stage pressure storage tank which are connected to each other;

[0006] The energy storage fluid outputted from the first-stage pressure storage tank flows to the second-stage pressure storage tank after being pressurized by renewable energy, and the energy storage fluid outputted from the second-stage pressure storage tank flows to the third-stage pressure storage tank after being pressurized by renewable energy;

[0007] The first flow splitting component is used to split the energy storage fluid output from the third-level pressure storage tank to obtain a first flow stream flowing to the first-level pressure storage tank and a second flow stream flowing to the second-level pressure storage tank, and adjust the ratio of the first flow stream to the second flow stream according to the power demand of the user's power system;

[0008] The first energy conversion device is disposed on the passage from the first flow distribution component to the first-stage pressure storage tank, and the first energy conversion device is in communication with the second-stage pressure storage tank, and the first energy conversion device is used to convert the pressure energy released by the first flow stream into energy for supplying power to the user's power system;

[0009] The second energy conversion device is arranged on the passage from the third-stage pressure storage tank to the first flow dividing component, and is used to convert the pressure energy released by the energy storage fluid output by the third-stage pressure storage tank into energy for supplying power to the user's power system;

[0010] The energy storage system also includes at least one heat exchange device, each of the heat exchange devices includes two channels that are not connected to each other, the two channels of each heat exchange device are respectively connected in series in the first heat exchange circuit and the energy storage circuit, and each heat exchange device is used to exchange heat between fluids of different circuits flowing in the two channels of the heat exchange device.

[0011] Optionally, the system further comprises:

[0012] A fourth-stage pressure storage tank, wherein the energy storage fluid outputted from the third-stage pressure storage tank is further pressurized by renewable energy and flows to the fourth-stage pressure storage tank;

[0013] a second flow splitting component, used for splitting the energy storage fluid outputted from the fourth-stage pressure storage tank to obtain a third flow stream flowing to the third-stage pressure storage tank and a fourth flow stream flowing to the second energy conversion device, and adjusting the ratio of the third flow stream to the fourth flow stream according to the power demand of the user power system;

[0014] The third energy conversion device is arranged on the passage from the fourth-stage pressure storage tank to the second diversion component, and is used for converting the pressure energy released by the energy storage fluid output by the fourth-stage pressure storage tank into energy for supplying power to the user's power system.

[0015] Optionally, the first heat exchange circuit includes a heat collection device for collecting thermal energy; in the at least one heat exchange device, at least one heating device is included for heating the energy storage fluid using the thermal energy provided by the heat collection device, and the channels of each heating device connected in series in the energy storage circuit are arranged on the passage flowing into any energy conversion device.

[0016] Optionally, the first heat exchange circuit also includes an underground heat storage device for recovering the thermal energy.

[0017] Optionally, the heat collection device includes a solar heat collection device and / or a geothermal heat collection device.

[0018] Optionally, the energy storage system also includes a second heat exchange circuit, which includes a cold collection device for collecting cold energy; in the at least one heat exchange device, at least one cooling device is included for cooling the energy storage fluid using the cold energy provided by the cold collection device, and the channels of each cooling device connected in series in the energy storage circuit are arranged on the passage flowing out of any energy conversion device.

[0019] Optionally, the energy storage circuit also includes:

[0020] A plurality of heat recovery devices, each of which includes two channels that are not connected to each other, the two channels in each of the heat recovery devices are connected in series in the energy storage circuit, the flow direction of one channel in each of the heat recovery devices is from the Nth level pressure storage tank to the N-1th energy conversion device, and the flow direction of the other channel in each of the heat recovery devices is from the N-1th level pressure storage tank to the N-1th energy conversion device, and N is a positive integer greater than 1.

[0021] Optionally, the renewable energy is wind and photovoltaic energy, and the energy storage system further includes:

[0022] A plurality of wind and photovoltaic power hydraulic pumps, each of which is arranged on an output passage of each pressure storage tank except the highest pressure storage tank, and is used to pressurize the energy storage fluid based on wind and photovoltaic power.

[0023] Optionally, the energy storage system further comprises:

[0024] A throttle valve is arranged on the output passage of each storage tank, and each throttle valve is used to adjust the pressure of the energy storage fluid output by the corresponding storage tank.

[0025] The present application also provides a control method for an energy storage system, which is applied to the energy storage system provided by any technical solution of the present application, and the method includes:

[0026] Determine the ratio of the two streams flowing out of each flow splitting component according to the power demand of the user's power system;

[0027] Control each of the flow diversion components to adjust according to the determined ratio.

[0028] Based on the above embodiments, the present application has at least the following beneficial effects or advantages:

[0029] The energy storage system comprises an energy storage circuit in which an energy storage fluid flows and a first heat exchange circuit in which a heat exchange fluid flows; the energy storage circuit is provided with a first energy conversion device, a second energy conversion device, a first flow splitter assembly, a first-stage pressure storage tank, a second-stage pressure storage tank and a third-stage pressure storage tank in communication with each other; the energy storage fluid outputted from the first-stage pressure storage tank flows to the second-stage pressure storage tank after being pressurized by renewable energy, and the energy storage fluid outputted from the second-stage pressure storage tank flows to the third-stage pressure storage tank after being pressurized by renewable energy; the first flow splitter assembly is used to split the energy storage fluid outputted from the third-stage pressure storage tank to obtain a first flow stream flowing to the first-stage pressure storage tank and a second flow stream flowing to the second-stage pressure storage tank, and to adjust the ratio of the first flow stream to the second flow stream according to the power demand of the user's power system; The first energy conversion device is arranged on the passage from the first diversion component to the first-stage pressure storage tank, and the first energy conversion device is connected to the second-stage pressure storage tank. The first energy conversion device is used to convert the pressure energy released by the first stream into energy for supplying power to the user's power system; the second energy conversion device is arranged on the passage from the third-stage pressure storage tank to the first diversion component, and is used to convert the pressure energy released by the energy storage fluid output by the third-stage pressure storage tank into energy for supplying power to the user's power system; the energy storage system also includes at least one heat exchange device, each heat exchange device includes two channels that are not connected to each other, and the two channels of each heat exchange device are respectively connected in series in the first heat exchange circuit and the energy storage circuit, and each heat exchange device is used to exchange heat between fluids of different circuits flowing in the two channels of the heat exchange device.

[0030] The embodiment of the present application divides the high-pressure energy storage fluid of the third-stage pressure storage tank into a first stream and a second stream through a first diversion component, uses the first stream to do work to supply power to the user's power system, recovers the second stream that does not do work through the second-stage pressure storage tank, and adjusts the ratio of the first stream to the second stream according to the needs of the user's power system, thereby improving the energy utilization efficiency in the energy storage system.

[0031] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0033] Figure 1 A schematic diagram of the structure of an energy storage system provided according to an embodiment of the present application Figure 1 ;

[0034] Figure 2 A schematic diagram of the structure of an energy storage system provided according to an embodiment of the present application Figure 2 ;

[0035] Figure 3 A schematic diagram of the structure of a first heat exchange circuit in an energy storage system provided according to an embodiment of the present application;

[0036] Figure 4 A schematic diagram of the structure of a second heat exchange circuit in an energy storage system provided according to an embodiment of the present application;

[0037] Figure 5 A schematic diagram of the structure of an energy storage system in mode 1 of the energy release stage according to an embodiment of the present application;

[0038] Figure 6 A schematic diagram of the structure of an energy storage system in mode 2 of the energy release stage according to an embodiment of the present application;

[0039] Figure 7 A schematic diagram of the structure of an energy storage system in mode three of the energy release stage provided according to an embodiment of the present application;

[0040] Figure 8 A schematic diagram of the structure of an energy storage system in energy release stage mode 4 according to an embodiment of the present application;

[0041] Fig. 9 A schematic diagram of the structure of an energy storage system in energy release stage mode 5 according to an embodiment of the present application;

[0042] Fig.10 A schematic diagram of the structure of an energy storage system in energy storage stage mode 1 provided according to an embodiment of the present application;

[0043] Fig.11 A schematic diagram of the structure of an energy storage system in energy storage stage mode 2 provided according to an embodiment of the present application;

[0044] Fig.12 This is a structural schematic diagram of an energy storage system in energy storage stage mode three provided according to an embodiment of the present application.

[0045] In the accompanying drawings, some of the reference numerals represent the following:

[0046] 101. Third-stage pressure storage tank, 102. Throttle valve of third-stage pressure storage tank, 103. Second-stage preheater, 104. Second-stage regenerator, 105. Second-stage heater, 106. Second energy conversion device, 107. First flow divider, 1071. First three-way valve, 1072. Second three-way valve, 108. First-stage reheater, 109. First energy conversion device, 110. First-stage regenerator, 111. First-stage cooler, 112. Cold storage unit, 113. First-stage pressure storage tank, 114. Throttle valve of first-stage pressure storage tank, 115. First-stage heater, 116. First-stage hydraulic pump, 117. First-stage preheater, 118. Second-stage pressure storage tank, 119. First throttle valve of second-stage pressure storage tank, 120. Second-stage cooler, 121, second throttle valve of second-stage pressure storage tank, 122, buried pipe heat exchanger, 123, second-stage hydraulic pump, 124, solar thermal collection unit, 125, heat storage unit, 127, third-stage hydraulic pump, 128, fourth-stage pressure storage tank, 129, throttle valve of fourth-stage pressure storage tank, 130, third-stage preheater, 131, third-stage reheater, 132, third-stage heater, 133, third energy conversion device, 134, second diversion component, 1341, third three-way valve, 1342, fourth three-way valve, 135, second-stage reheater, 136, third-stage cooler, 137, water tank, 138, first buried heat storage device, 139, second buried heat storage device, 140, third buried heat storage device, 141, external cold source. DETAILED DESCRIPTION

[0047] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0048] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0049] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0050] The present application embodiment provides an energy storage system, referring to Figure 1 The energy storage system includes an energy storage circuit in which an energy storage fluid flows and a first heat exchange circuit in which a heat exchange fluid flows. Figure 1 The energy storage fluid is a fluid that stores energy through pressure, and can be a liquid, a gas, or a medium in a critical state or a supercritical state. Optionally, the energy storage fluid can be carbon dioxide. Depending on the temperature and air pressure, carbon dioxide may be in different stages of liquid, gas, or supercritical state in different parts of the energy storage circuit.

[0051] The energy storage circuit is provided with a first energy conversion device 109 , a second energy conversion device 106 , a first flow diversion component 107 , a first-stage pressure storage tank 113 , a second-stage pressure storage tank 118 and a third-stage pressure storage tank 101 which are connected to each other.

[0052] The energy storage fluid output by the first-stage pressure storage tank 113 flows to the second-stage pressure storage tank 118 after being pressurized by renewable energy, and the energy storage fluid output by the second-stage pressure storage tank 118 flows to the third-stage pressure storage tank 101 after being pressurized by renewable energy. Optionally, the pressurizing module can be a hydraulic pump, and the renewable energy can use wind energy and / or light energy. After the renewable energy is converted into electrical energy, the hydraulic pump is driven to pressurize the energy storage fluid. By pressurizing the energy storage fluid with renewable energy, renewable green energy can be converted into pressure energy, and the renewable energy can be stored in the form of storing the pressure energy of the energy storage fluid, thereby improving the environmental protection effect of the energy storage system. It can be understood that in addition to the above-mentioned three-stage pressure storage tanks, more levels of pressure storage tanks can be provided in the energy storage system provided in the embodiment of the present invention. For example, refer to Figure 2 The energy storage system may further include: a fourth-stage pressure storage tank 128 , and the energy storage fluid outputted from the third-stage pressure storage tank 101 flows to the fourth-stage pressure storage tank 128 after being pressurized by renewable energy.

[0053] For example, the device for pressurizing the energy storage fluid in the energy storage system may be a wind power hydraulic pump using wind power, each wind power hydraulic pump being arranged on the output path of each pressure storage tank except the highest pressure storage tank, for pressurizing the energy storage fluid based on wind power. Figure 1 , the energy storage system may include a first stage hydraulic pump 116 and a second stage hydraulic pump 123. Figure 2 , the energy storage system may further include a third stage hydraulic pump 127 .

[0054] The pressures of the third-stage pressure storage tank 101, the second-stage pressure storage tank 118, and the first-stage pressure storage tank 113 are decreasing, which are equivalent to high-pressure pressure storage tanks, medium-pressure pressure storage tanks, and low-pressure pressure storage tanks, respectively. The specific pressure value design of each pressure storage tank can be determined according to actual conditions, and this embodiment does not limit this. By providing pressure to the energy storage fluid output by the low-pressure pressure storage tank and the medium-pressure pressure storage tank with the energy of renewable energy, renewable energy can be converted into pressure energy of the energy storage fluid, which is then stored, and the pressure energy can be converted into electrical energy when there is a power supply demand in the user's power system.

[0055] Optionally, the conversion process may be to convert pressure energy into mechanical energy first, and then convert mechanical energy into electrical energy. For example, the pressure energy of the energy storage fluid may be converted into mechanical energy by a pneumatic turbine, and then converted into electrical energy by a generator.

[0056] The first energy conversion device 109 is arranged on the passage from the first flow distribution component 107 to the first-stage pressure storage tank 113, and the first energy conversion device 109 is connected to the second-stage pressure storage tank 118. The first energy conversion device 109 is used to convert the pressure energy released by the first flow stream into energy for supplying power to the user's power system. The first energy conversion device 109 can be a turbine device, which is used to convert the pressure energy of the energy storage fluid into mechanical energy, and then the mechanical energy can be used to do work and converted into electrical energy for supplying power to the user's power system. For example, the turbine device can be a steam turbine, an expander, etc.

[0057] The first flow diversion component 107 is used to divert the energy storage fluid output from the third-stage pressure storage tank 101 to obtain a first flow stream flowing to the first-stage pressure storage tank 113 and a second flow stream flowing to the second-stage pressure storage tank 118, and adjust the ratio of the first flow stream to the second flow stream according to the power demand of the user's power system. The first flow stream performs work to supply power to the user's power system through the first energy conversion device 109, and the second flow stream that does not perform work is recovered through the second-stage pressure storage tank 118, thereby reducing the energy waste of the collected renewable energy, and recovering the pressure energy that does not perform work into the second-stage pressure storage tank 118, thereby improving the energy utilization efficiency of the energy storage system. In addition, this embodiment does not need to adjust the flow rate at the outlet of the third-stage pressure storage tank 101, so that the output of the third-stage pressure storage tank 101 can be kept stable, and the energy storage fluid is transported outward at a constant flow rate. The first flow diversion component 107 can adjust the ratio of the first flow stream to the second flow stream according to the peak and valley conditions of the user's power system. Reference Figure 1 The first flow dividing component 107 may include a first three-way valve 1071 and a second three-way valve 1072 .

[0058] The second energy conversion device 106 is arranged on the passage from the third-stage pressure storage tank 101 to the first flow diversion component 107, and is used to convert the pressure energy released by the energy storage fluid output by the third-stage pressure storage tank 101 into energy for supplying power to the user's power system. By respectively arranging two energy conversion devices at the outlet of the third-stage pressure storage tank 101 and the outlet of the first flow stream of the first flow diversion component 107, the pressure energy of the energy storage fluid can be fully converted, the released energy can be effectively increased, and the pressure energy conversion efficiency can be improved.

[0059] The energy storage system also includes at least one heat exchange device, each heat exchange device includes two channels that are not connected to each other, the two channels of each heat exchange device are respectively connected in series in the first heat exchange circuit and the energy storage circuit, the channel connected in series in the first heat exchange circuit circulates heat exchange fluid, and the channel connected in series in the energy storage circuit circulates energy storage fluid, and each heat exchange device is used to exchange heat between fluids of different circuits flowing in the two channels of the heat exchange device.

[0060] It is understood that when the energy storage system provided in the embodiment of the present invention further includes a fourth-stage pressure storage tank, it also includes the following components: a second flow splitting component 134, which is used to split the energy storage fluid output from the fourth-stage pressure storage tank 128 to obtain a third flow stream flowing to the third-stage pressure storage tank 101 and a fourth flow stream flowing to the second energy conversion device 106, and adjust the ratio of the third flow stream to the fourth flow stream according to the power demand of the user's power system. Figure 2 The second flow dividing component 134 may include a third three-way valve 1341 and a fourth three-way valve 1342 .

[0061] The third energy conversion device 133 is arranged on the passage from the fourth-stage pressure storage tank 128 to the second diversion component 134, and is used for converting the pressure energy released by the energy storage fluid output by the fourth-stage pressure storage tank 128 into energy for supplying power to the user's power system.

[0062] Similarly, the embodiments of the present invention may also be provided with more levels of pressure storage tanks, which cannot be listed one by one. By adding multiple levels of pressure storage tanks, more detailed level differences can be created for energy storage, utilization and recycling, thereby significantly improving energy utilization efficiency.

[0063] Optionally, the energy storage system further comprises a throttle valve disposed on the output passage of each storage tank, each throttle valve being used to adjust the pressure of the energy storage fluid outputted by the corresponding storage tank, Figure 1 and Figure 2 The throttle valves of each level of pressure storage tanks are used to stabilize the pressure of the energy storage fluid output by each pressure storage tank, thereby improving the pressure stability of the energy storage fluid output by the pressure storage tank and improving the pressure balance capacity of the entire energy storage circuit. Figure 3 , also includes a throttle valve 129 of the fourth-stage pressure storage tank.

[0064] Optionally, the energy storage circuit may further include: a plurality of heat recovery devices, each heat recovery device includes two channels that are not connected to each other, the two channels in each heat recovery device are connected in series in the energy storage circuit, the flow direction of one channel in each heat recovery device is from the Nth level pressure storage tank to the N-1th energy conversion device, and the flow direction of another channel in each heat recovery device is from the N-1th level pressure storage tank to the N-1th energy conversion device, where N is a positive integer greater than 1. Reference Figure 1 The plurality of heat recovery devices include a first stage heat recovery device 110 and a second stage heat recovery device 104. Figure 2 The multiple heat recovery devices may further include a third-stage heat recovery device 131.

[0065] The heat of the energy storage fluid flowing out of each energy conversion device can be recovered through the heat recovery device, and the heat energy can be used to heat the energy storage fluid flowing into the energy conversion device, thereby fully utilizing the heat energy of the energy storage fluid and improving the thermal energy utilization efficiency.

[0066] Optionally, the first heat exchange loop may include a heat collection device for collecting heat energy, and the heat collection device may collect heat, for example, solar energy, geothermal energy, etc. In at least one heat exchange device, at least one heating device is included for heating the energy storage fluid using the heat energy provided by the heat collection device, and the channels of each heating device connected in series in the energy storage loop are arranged on the path flowing into any energy conversion device. Optionally, refer to Figure 1 The heating device in the first heat exchange loop may include a first stage heater 115 and a second stage heater 105. Optionally, the heat collection device includes a solar heat collection device and / or a geothermal heat collection device. Figure 1 The heat collection device is a solar heat collection unit 124. The solar heat collection unit 124 is used to convert solar energy into heat energy of a heat exchange fluid. The green energy collected by the solar heat collection unit 124 is used to heat the energy storage fluid, thereby improving the environmental protection effect of the energy storage system. Figure 2 For the added fourth-stage pressure storage tank 128 , the heating device in the first heat exchange loop may also include a third-stage heater 132 .

[0067] Further, refer to Figure 1 , the heating device in the first heat exchange loop may also include a first stage preheater 117 and a second stage preheater 103. Taking the second stage preheater 103 as an example to illustrate the role of the preheater, the second stage preheater 103 can increase the temperature of the energy storage fluid output by the third stage pressure storage tank 101, which is conducive to converting the liquid energy storage fluid output by the third stage pressure storage tank 101 into a supercritical or gaseous energy storage fluid, making it convenient for the subsequent connected energy conversion device to use the pressure energy of the energy storage fluid to do work, thereby improving the energy conversion efficiency of the energy conversion device. Figure 2For the added fourth-stage pressure storage tank 128 , the heating device in the first heat exchange circuit may further include a third-stage preheater 130 .

[0068] Optionally, at least one heating device may further include a reheating device. Figure 1 The reheating device includes a first-stage reheater 108, which is arranged on the passage flowing into the first energy conversion device 109 to heat the energy storage fluid flowing into the first energy conversion device 109. Figure 2 The reheat device may further include a second-stage reheater 135, which is disposed on the passage flowing into the second energy conversion device 106 to heat the energy storage fluid flowing into the second energy conversion device 106. The reheat device can improve the energy conversion efficiency of the energy conversion device.

[0069] Optionally, the first heat exchange loop also includes an underground heat storage device for recovering heat energy to store excess heat energy in the first heat exchange loop.

[0070] Optionally, the energy storage system may further include a second heat exchange circuit, the first heat exchange circuit and the second heat exchange circuit are not interconnected, and the heat exchange fluid in the second heat exchange circuit is used as a cold source for cooling the energy storage fluid in the energy storage circuit. The second heat exchange circuit includes a cold collection device for collecting cold energy; the cold collection device can collect cold energy, for example, cold energy from air, water, and liquid natural gas in a building. At least one heat exchange device includes at least one cooling device for cooling the energy storage fluid using the cold energy provided by the cold collection device, and the channels of the cooling devices connected in series in the energy storage circuit are arranged on the passage flowing out from any energy conversion device. Reference Figure 1 The cooling device includes a first-stage cooler 111 and a second-stage cooler 120, referring to Figure 2 The cooling device may further include a third-stage cooler 136. The cold energy collected by the cooling device can cool the energy storage fluid when passing through the cooling device before the energy storage fluid is recovered in the energy storage loop, thereby compressing the volume of the energy storage fluid, increasing the pressure of the energy storage fluid, and improving the efficiency of the energy storage fluid in storing pressure energy. The effect of the cooler cooling the energy storage fluid is illustrated by taking the second-stage cooler 120 as an example, which helps to convert the gaseous or supercritical energy storage fluid back to the liquid state, thereby improving the energy storage efficiency of the second-stage pressure storage tank 118.

[0071] Through the first heat exchange circuit, the temperature of the energy storage fluid circulating in the energy storage system can be adjusted to achieve control over the switching of the energy storage fluid between different states such as gas, liquid, and supercritical states. By specifically setting the position of the heat exchange device in the energy storage circuit, the temperature of the energy storage fluid can be adjusted to improve the efficiency of the energy storage fluid in releasing and storing energy.

[0072] refer to Figure 3 , which is an embodiment of the present invention Figure 2 The embodiment provides a specific implementation of a first heat exchange loop in an energy storage system. The first heat exchange loop is Figure 3 The circuit shown by the dashed line in the middle shows that the heat exchange fluid flows along Figure 3 The first heat exchange loop is equivalent to the circulation of the heat storage unit 125. The first heat exchange loop includes: Figure 3 The first heat exchange circuit includes a plurality of underground heat storage devices: a first underground heat storage device 138, a second underground heat storage device 139 and a third underground heat storage device 140. The three circuits are described as follows:

[0073] refer to Figure 3 , loop 1 includes: after the heat storage unit 125 collects the heat of the solar thermal collection unit 124, it releases the working medium (water, oil or other) to the third-stage heater 132 as a heat source. After the working medium is cooled once, optionally, the excess heat can be stored in the first underground thermal storage device 138, and the working medium is cooled twice; then it passes through the second-stage heater 105, as the heat source of the second-stage heater 105, the working medium is cooled three times, optionally, the excess heat is stored in the first underground thermal storage device 138, and the working medium is cooled four times; then, it passes through the first-stage heater 115, as the heat source of the first-stage heater, and finally passes through the first underground thermal storage device 138 to store the remaining heat in the soil, and finally returns to the solar thermal collection unit 124 for heating. The underground thermal storage device in this loop is in the heat storage process.

[0074] refer to Figure 3 , loop 2 includes: the working medium in the storage tank (specifically, the water tank 137) for storing the working medium (i.e., the heat exchange fluid, which can be water or other), after entering the second underground heat storage device 139, the working medium is heated for the first time, enters the third-stage preheater 130 as a heat source, the working medium is cooled for the first time, and then enters the second underground heat storage device 139, the working medium is heated for the second time; then enters the second-stage preheater 103 as a heat source, the working medium is cooled for the second time, then enters the second underground heat storage device 139, the working medium is heated for the third time; finally enters the first-stage preheater as a heat source, the working medium is cooled for the third time, and finally returns to the water tank 137. The underground heat storage device in this loop is in the heat release process.

[0075] refer to Figure 3 , loop three includes: after the heat storage unit 125 collects the heat from the solar thermal collection unit 124, it releases the working medium (water, oil or other) and passes through the second stage reheater 135 and the first stage reheater 108 as a heat source; optionally, it then enters the third underground thermal storage device 140 to store the excess heat in the soil, and finally returns to the solar thermal collection unit 124 for heating. The underground thermal storage device in this loop is in the heat storage process.

[0076] It should be noted that: after the first underground heat storage device 138 in the underground heat storage device has stored heat for a certain period of time / when the heat storage is nearly saturated, or after the second underground heat storage device 139 has released heat for a certain period of time / when the heat release is nearly saturated, the first underground heat storage device 138 and the second underground heat storage device 139 need to be exchanged, that is, the first underground heat storage device 138 is connected to loop two, and the second underground heat storage device 139 is connected to loop one, and the third underground heat storage device 140 can be provided as a backup heat source to loop one or other components that require heat, such as heat pumps.

[0077] refer to Figure 4 , is the second heat exchange loop in the embodiment of the present invention, the heat exchange fluid flows in the direction of the dotted arrow, the second heat exchange loop can be a cold source loop, the cold storage unit 112 releases the working medium (i.e., the heat exchange fluid), which passes through the first stage cooler 111, the second stage cooler 120, and the third stage cooler 136 successively, as a cold source for cooling the energy storage fluid. After the working medium is heated up, the working medium can be cooled down by the external cold source 141 and then stored in the cold storage unit 112.

[0078] Reference below Figure 1 The technical solution for applying the energy storage system provided in this embodiment in a specific application scenario is described in detail.

[0079] With the improvement of industrialization and rapid economic development, global energy demand is experiencing a surge, which also brings about excessive emissions of greenhouse gas carbon dioxide. In order to solve the environmental problems caused by excessive carbon dioxide emissions, the global energy structure is leaning towards clean energy. However, renewable energy sources such as wind power and solar power are intermittent, which means that the excess electricity they may generate cannot be used. At the same time, due to the inherent characteristics of renewable energy and the mismatch between renewable energy generation and user power systems, the abandonment rate of green electricity is high, and only a part of renewable energy generation can be supplied to power terminals. In addition, therefore, the application of energy storage technology is an effective solution to the above problems.

[0080] At present, there are many mature energy storage technologies that have been put into commercial application, such as pumped storage and compressed gas energy storage. Pumped storage has higher energy storage efficiency than compressed gas energy storage, but it is difficult to be widely used due to its geographical environment. There are currently two types of compressed gas energy storage, one is compressed air energy storage, and the other is compressed carbon dioxide energy storage. Both of them generally have problems such as low energy storage density. However, the excellent thermophysical thermal properties of carbon dioxide and its more suitable critical point make it easier to achieve supercritical or liquid storage than air. Therefore, the compressed energy storage system with carbon dioxide as the energy storage medium has better energy storage density than the system with air as the working fluid. At present, the research on liquid carbon dioxide energy storage system mainly focuses on the following aspects: designing a better system cycle and evaluating the system performance from the perspective of economics and thermodynamics. Few studies point to the coupling of liquid carbon dioxide energy storage with renewable energy and the regulation of energy storage and release of liquid carbon dioxide energy storage system.

[0081] This embodiment provides an energy storage system that uses liquid carbon dioxide to store energy. The system includes a liquid carbon dioxide storage and release unit, a solar thermal collection unit 124, a heat storage unit 125, a soil source heat storage unit 125, and a cold storage unit 112. The system aims to optimize the cycle of the energy storage system. By adding an intermediate pressure storage tank, a new user power system peak-shaving strategy is provided, and multi-stage compression and multi-stage expansion of liquid carbon dioxide are also realized. Through the use of a photoelectric hydraulic pump in the energy storage system, the heat exchange loss of vaporization during energy release of the liquid carbon dioxide energy storage system is reduced. At the same time, the solar thermal collection unit 124, the heat storage unit 125, the cold storage unit 112 and the soil source heat storage unit 125 are combined to provide corresponding thermal energy (including heat energy and cold energy) for the liquid carbon dioxide storage and release unit, so as to achieve the purpose of cold and heat storage, and improve the thermal energy utilization efficiency of the energy storage system through the cascade utilization of thermal energy.

[0082] The following is for Figure 1 The operation and control method of the energy storage system including the three-stage pressure storage tank shown in FIG. Figures 5 to 9 There are five working modes shown in the figure. In the energy storage stage, they include Figure 10 to Figure 12 There are three working modes shown in .

[0083] refer to Figure 5 , Energy release stage mode 1:

[0084] The third-stage pressure storage tank 101 releases the liquid energy storage medium which passes through the second-stage preheater 103, the second-stage regenerator 104, and the second-stage heater 105 in sequence through the pipeline, is heated and vaporized to a gaseous or supercritical state, and then enters the steam turbine (equivalent to the second energy conversion device 106) to perform work, and then enters the second-stage regenerator 104 and the second-stage cooler 120 to be cooled into a liquid state and enter the second-stage pressure storage tank 118.

[0085] refer to Figure 6 , Energy release stage mode 2:

[0086] The energy storage medium released from the third-stage pressure storage tank 101 passes through the second-stage preheater 103, the second-stage regenerator 104, and the second-stage heater 105 through the pipeline in sequence, and is vaporized to a gaseous state or a supercritical state. After entering the steam turbine to perform work, it enters the diverter valve (the first three-way valve 1071). One stream flowing out of the diverter valve passes through the second-stage regenerator 104 and the second-stage cooler 120 to be cooled into a liquid state, and then enters the second-stage pressure storage tank 118 for storage. The other stream flowing out of the diverter valve is heated by the first-stage reheater 108 and then enters the expander (equivalent to the first energy conversion device 109). After performing work, it passes through the second-stage cooler 120 to be liquefied and then enters the first-stage pressure storage tank 113 for storage. According to the user's electricity demand, the ratio of the flow to the second-stage pressure storage tank 118 and the first-stage pressure storage tank 113 is adjusted.

[0087] refer to Figure 7 , Energy release stage mode three:

[0088] The energy storage medium released from the third-stage pressure storage tank 101 passes through the second-stage preheater 103, the second-stage reheater 104, and the second-stage heater 105 through a pipeline, and is vaporized to a gaseous state or a supercritical state, and then enters the steam turbine to perform work. Subsequently, it is heated in the first-stage reheater 108 and then enters the expander to perform work. After that, it passes through the second-stage reheater 104 and the first-stage cooler 111 in sequence to be cooled into a liquid state, and then enters the first-stage pressure storage tank 113.

[0089] refer to Figure 8 , Energy release stage mode four:

[0090] The energy storage medium released by the third-stage pressure storage tank 101 passes through the second-stage preheater 103, the second-stage reheater 104, and the second-stage heater 105 through the pipeline in sequence, and is vaporized to a gaseous state or a supercritical state, and then enters the steam turbine to perform work; at the same time, the energy storage medium released by the second-stage pressure storage tank 118 passes through the first-stage preheater 117, the first-stage reheater 110, and the first-stage heater 115 through the pipeline in sequence, and is vaporized to a gaseous state or a supercritical state, and enters the diverter valve, and after being mixed with the energy storage medium released by the third-stage pressure storage tank 101 at the diverter valve, it is heated by the first-stage reheater 108, and then enters the expander to perform work; the flow stream at the outlet of the expander passes through the second-stage reheater 104, the first-stage reheater 110, and the first-stage cooler 111 in sequence, and after being cooled into a liquid state, it enters the first-stage pressure storage tank 113 for storage.

[0091] refer to Fig. 9 , Energy release stage mode five:

[0092] The energy storage medium released from the second-stage pressure storage tank 118 passes through the first-stage preheater 117, the first-stage reheater 110, and the first-stage heater 115 through a pipeline to be vaporized to a gaseous state or a supercritical state, and then enters the expander to perform work after being heated by the first-stage reheater 108. The flow stream at the outlet of the expander passes through the first-stage reheater 110 and the first-stage cooler 111 in sequence, and after being cooled into a liquid state, enters the first-stage pressure storage tank 113 for storage.

[0093] refer to Fig.10 Energy storage stage mode 1: The first-stage pressure storage tank 113 releases the energy storage medium, which passes through the throttle valve 114 of the first-stage pressure storage tank 113 and enters the first-stage hydraulic pump 116. The first-stage hydraulic pump 116 is driven by the excess wind and solar power, and the energy storage medium is pressurized and enters the second-stage pressure storage tank 118 for storage.

[0094] refer to Fig.11 Energy storage stage mode two: the second-stage pressure storage tank 118 releases the energy storage medium, which passes through the throttle valve of the second-stage pressure storage tank 118 and enters the second-stage hydraulic pump 123. The second-stage hydraulic pump 123 is driven by the excess wind and solar power, and the energy storage medium is pressurized and enters the third-stage pressure storage tank 101 for storage.

[0095] refer to Fig.12 Energy storage stage mode three: the first-stage pressure storage tank 113 releases the energy storage medium, which passes through the throttle valve 114 of the first-stage pressure storage tank 113 and then enters the first-stage hydraulic pump 116. The first-stage hydraulic pump 116 is driven by the excess wind and solar power to pressurize the energy storage medium. After that, the energy storage medium is pressurized by the second-stage hydraulic pump 123 and then enters the third-stage pressure storage tank 101 for storage.

[0096] Further, Figure 1 The structure of the energy storage system shown and its working principle are explained in detail:

[0097] refer to Figure 1 The above-mentioned liquid carbon dioxide energy storage and release unit includes: a third-stage pressure storage tank 101, a throttle valve 102 of the third-stage pressure storage tank 101, a second energy conversion device 106 (specifically, it can be a steam turbine), a first diversion component 107 (specifically, it can be a three-way valve), a first energy conversion device 109 (specifically, it can be an expander), a first-stage pressure storage tank 113, a throttle valve 114 of the first-stage pressure storage tank 113, a first-stage hydraulic pump 116, a second-stage pressure storage tank 118, a first throttle valve 119 of the second-stage pressure storage tank 118, a second throttle valve 121 of the second-stage pressure storage tank 118, and a second-stage hydraulic pump 123.

[0098] The energy storage system further comprises a high-pressure carbon dioxide vaporization heating unit, specifically comprising: a second-stage preheater 103 and a third-stage heater 132. The energy storage system further comprises a medium-pressure carbon dioxide vaporization heating unit, specifically comprising: a first-stage preheater 117 and a second-stage heater 105.

[0099] Figure 1 In the structure of the energy storage system shown, the specific connection relationship of each component includes:

[0100] The outlet of the third-stage pressure storage tank 101 is connected through a pipeline in sequence through the high-pressure pressure storage tank throttle valve, the low-temperature side of the second-stage preheater 103, the low-temperature side of the second-stage regenerator 104, the low-temperature side of the third-stage heater 132, the second energy conversion device 106, and the first diverter assembly 107. A stream of the first diverter assembly 107 is connected to the inlet of the second-stage pressure storage tank 118 through a pipeline in sequence through the high-temperature side of the second-stage regenerator 104 and the high-temperature side of the second-stage cooler 120. The outlet of the second-stage pressure storage tank 118 is mixed with the stream on the other side of the first diverter assembly 107 through a pipeline in sequence through the first throttle valve 119 of the second-stage pressure storage tank 118, the low-temperature side of the first-stage preheater 117, the low-temperature side of the first-stage regenerator 110, and the low-temperature side of the second-stage heater 105. The mixed stream is connected to the inlet of the first-stage pressure storage tank 113 through the pipeline in sequence through the low-temperature side of the reheater, the first energy conversion device 109, the high-temperature side of the first-stage heat exchanger 110, and the high-temperature side of the first-stage cooler 111. The outlet of the first-stage pressure storage tank 113 is connected to the other inlet of the second-stage pressure storage tank 118 through the pipeline in sequence through the throttle valve 114 of the first-stage pressure storage tank 113 and the first-stage hydraulic pump 116. The other outlet of the second-stage pressure storage tank 118 is connected to the inlet of the third-stage pressure storage tank 101 through the pipeline in sequence through the second throttle valve 121 of the second-stage pressure storage tank 118 and the second-stage hydraulic pump 123. By adding the second-stage pressure storage tank 118 between the third-stage pressure storage tank 101 and the first-stage pressure storage tank 113, the storage and release energy can be adjusted through the flow distribution of the first diversion component 107. Optionally, the third-stage pressure storage tank 101 can reach the minimum rated pressure at each energy release.

[0101] The energy storage system also includes a shallow geothermal utilization unit, specifically including: a ground pipe heat exchanger 122, wherein the ground pipe heat exchanger 122 is composed of a plurality of ground pipes connected in series. The outlet of the cold storage unit 112 is connected to the first-stage cooler 111 through a pipeline. The outlet of the solar thermal collection unit 124 is connected to the thermal storage unit 125 through a pipeline, and one of the streams at the outlet of the thermal storage unit 125 is connected to the inlet of the solar thermal collection unit 124 through a pipeline in sequence through the high-temperature side of the third-stage heater 132, the high-temperature side of the second-stage preheater 103, the ground pipe heat exchanger 122, the low-temperature side of the second-stage cooler 120, the high-temperature side of the second-stage heater 105, and the high-temperature side of the first-stage preheater 117, and the other stream at the outlet of the thermal storage unit 125 is connected to the inlet of the solar thermal collection unit 124 through a pipeline through the high-temperature side of the reheater. The light and heat collected by the solar thermal collection unit 124 is stored in the heat storage unit 125, and after releasing heat to the third-stage carbon dioxide vaporization heating unit, it is connected to the ground pipe heat exchanger 122. The heat exchange medium at the outlet of the solar thermal collection unit 124 enters the heat storage unit 125, and the heat exchange medium at the outlet of the heat storage unit 125 passes through the high temperature side of the third-stage heater 132, the high temperature side of the second-stage preheater 103, the ground pipe heat exchanger 122, the second-stage cooler 120, the second-stage heater 105, and the first-stage preheater 117 to connect with the solar thermal collection unit 124 to form a circulation loop; the heat exchange medium at the outlet of the heat storage unit 125 passes through the pipeline through the reheater to connect with the solar thermal collection unit 124 to form a second circulation loop.

[0102] The working principle and specific operation process of the energy storage system provided in this embodiment are as follows:

[0103] In the energy storage stage, only the liquid carbon dioxide energy storage and release system unit including the multi-stage pressure storage tank is working, which is divided into two working conditions, namely, the photovoltaic sufficient working condition and the photovoltaic insufficient working condition, among which:

[0104] When the photovoltaic power is sufficient, the outlet of the first-stage pressure storage tank 113 provides low-temperature and low-pressure liquid carbon dioxide, which enters the first-stage hydraulic pump 116 after passing through the throttle valve 114 of the first-stage pressure storage tank 113 to a stable pressure, and then enters the second-stage hydraulic pump 116. The first-stage hydraulic pump 116 pressurizes the liquid carbon dioxide to a low-temperature medium pressure under the drive of the photovoltaic power, and then enters the second-stage pressure storage tank 118 until the first-stage pressure storage tank 113 reaches the rated minimum pressure; at the same time, the outlet of the second-stage pressure storage tank 118 provides low-temperature and medium-pressure liquid carbon dioxide, which enters the second-stage hydraulic pump 123 after passing through the second throttle valve 121 of the second-stage pressure storage tank 118 to a stable pressure, and then enters the third-stage pressure storage tank 101. Until the second-stage pressure storage tank 118 reaches the minimum rated pressure, at the same time, the third-stage pressure storage tank 101 reaches the maximum rated pressure.

[0105] When the photoelectricity is insufficient, the operating process is the same as that of the photoelectricity is sufficient. The difference is that when the photoelectricity is insufficient, the first-stage hydraulic pump 116 is prioritized to work, and the second-stage hydraulic pump 123 stops working. After ensuring that the second-stage pressure storage tank 118 reaches the maximum rated pressure, the first-stage hydraulic pump 116 and the second-stage hydraulic pump 123 work at the same time.

[0106] In the energy release stage, the working cycle of the liquid carbon dioxide energy storage and release system unit including the multi-stage pressure storage tank is as follows: the third-stage pressure storage tank 101 provides high-pressure and low-temperature liquid carbon dioxide, which passes through the high-pressure pressure storage tank throttle valve to a stable pressure, passes through the low-temperature side of the second-stage preheater 103 to absorb the heat of the heat transfer medium of the heat storage unit 125, and then passes through the low-temperature side of the second-stage heat regenerator 104 to recover the waste heat at the outlet of the second energy conversion device 106, and then passes through the third-stage heater 132, and is heated to a high-temperature supercritical state by the heat transfer medium of the heat storage unit 125, and then enters the second energy conversion device 106 to generate power. The medium-temperature and medium-pressure carbon dioxide gas at the outlet of the second energy conversion device 106 enters the first diversion component 107 and is divided into two streams. The second stream passes through the high temperature side of the second stage regenerator 104 through the pipeline and then enters the high temperature side of the second stage cooler 120, and enters the second stage pressure storage tank 118. In addition, the second stream and the low temperature and medium pressure liquid carbon dioxide provided by the second stage pressure storage tank 118 are heated to medium temperature and medium pressure gaseous carbon dioxide through the low temperature side of the first stage preheater 117, the low temperature side of the first stage regenerator 110, and the low temperature side of the second stage heater 105, and then added to the first stream. After the first stream enters the reheater for heating, it enters the first energy conversion device 109 to do work. The flow of the two streams is controlled by the user's power load. When the power load is large, more flow flows to the reheater. When the power load is small, more flow flows to the high temperature side of the second stage regenerator 104. The low-pressure carbon dioxide after the outlet of the first energy conversion device 109 enters the high temperature side of the first stage regenerator 110 through the pipeline in turn, and the high temperature side of the first stage cooler 111 enters the first stage pressure storage tank 113, and the energy release ends.

[0107] The solar thermal collection unit 124 heats the heat transfer medium to a certain temperature and stores it in the heat storage unit 125. In the energy release stage, the heat storage unit 125 releases the heat transfer medium, one of which flows into the high-temperature side of the third-stage heater 132, the high-temperature side of the second-stage preheater 103, the buried pipe heat exchanger 122, the second-stage cooler 120, the second-stage heater 105, the first-stage preheater 117 in sequence through the pipeline and finally returns to the solar thermal collection unit 124 to form a circulation loop one; the other flow enters the high-temperature side of the reheater and finally returns to the solar thermal collection unit 124 to form a circulation loop two.

[0108] This embodiment proposes an energy storage system that can couple geothermal, solar thermal, wind and photovoltaic power, and use multi-level liquid carbon dioxide pressure storage tanks for peak load regulation. The energy storage system has the following characteristics:

[0109] 1. Use multiple storage tanks to adjust the storage and release power of the liquid carbon dioxide energy storage system. This method can make peak regulation more flexible, while keeping the flow rate of the storage tank output stable, ensuring the thermodynamic performance of components such as compressors and turbines, and reducing the risk of equipment fatigue and damage;

[0110] 2. When releasing energy, the heat from the liquefaction of the storage tank is recovered by using the regenerator to improve energy utilization;

[0111] 3. Multi-stage expansion and intermediate heating effectively increase the energy release;

[0112] 4. Innovatively couple the compressed energy storage system with wind, solar, solar and geothermal energy, which not only improves the utilization rate of renewable energy, but also reduces the heat exchange temperature difference and realizes the cascade utilization of energy.

[0113] From the analysis of the above technical scheme and its characteristics, it can be seen that the energy storage system of this embodiment has at least the following beneficial technical effects: combining wind photovoltaic, solar thermal, shallow geothermal and liquid carbon dioxide energy storage systems, reducing heat exchange losses through cascaded heat utilization, improving the utilization rate of renewable energy, and realizing the combined utilization of wind photovoltaic, solar thermal, geothermal and energy storage. By adding an intermediate pressure storage tank, a new peak-shaving strategy for the liquid carbon dioxide energy storage system is proposed, which can more flexibly control the pressure of the carbon dioxide storage tank.

[0114] The energy storage system provided in this embodiment can implement a peak-shaving strategy according to the peak and valley conditions of the user's power system, adjust energy storage and release, and reduce energy waste. In addition, the system structure of heat recovery device, multi-stage expansion and heating before expansion improves the energy conversion efficiency in the system. While absorbing photovoltaic storage as pressure energy, the system also stores and utilizes light heat and geothermal energy to provide the heat required in the energy storage system, reduce the heat exchange temperature difference, and improve the utilization rate of heat.

[0115] The present application also provides a method for controlling an energy storage system. The method can be applied to control the energy storage system provided by any technical solution of the above-mentioned embodiment of the present application. The method specifically comprises the following steps:

[0116] Step 1: Determine the ratio of the two streams flowing out of each flow splitting component according to the power demand of the user's power system;

[0117] Step 2: Control each of the diversion components to adjust according to the determined ratio.

[0118] The method can be applied to electronic devices, such as computers, processors, etc. After execution, the electronic devices output control signals to each shunt component to control each shunt component to adjust the shunt ratio.

[0119] For the parts not described in detail about the technical solutions and beneficial effects of the control method of the energy storage system provided in this embodiment, reference can be made to the relevant description of the energy storage system provided in the embodiment of the present application, and they will not be repeated here.

[0120] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0121] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0122] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

[0123] The solutions in this application specification and embodiments, if they involve the processing of personal information, will be processed on the premise of having a legal basis (such as obtaining the consent of the subject of personal information, or being necessary for the performance of a contract, etc.), and will only be processed within the scope of regulations or agreements. If a user refuses to process personal information other than the necessary information for basic functions, it will not affect the user's use of basic functions.

Claims

1. An energy storage system, characterized in that: The energy storage system comprises an energy storage circuit in which an energy storage fluid flows and a first heat exchange circuit in which a heat exchange fluid flows; The energy storage circuit is provided with a first energy conversion device, a second energy conversion device, a first flow dividing component, a first-stage pressure storage tank, a second-stage pressure storage tank and a third-stage pressure storage tank which are connected to each other; The energy storage fluid outputted from the first-stage pressure storage tank flows to the second-stage pressure storage tank after being pressurized by renewable energy, and the energy storage fluid outputted from the second-stage pressure storage tank flows to the third-stage pressure storage tank after being pressurized by renewable energy; The first flow splitting component is used to split the energy storage fluid output from the third-level pressure storage tank to obtain a first flow stream flowing to the first-level pressure storage tank and a second flow stream flowing to the second-level pressure storage tank, and adjust the ratio of the first flow stream to the second flow stream according to the power demand of the user's power system; The first energy conversion device is disposed on the passage from the first flow distribution component to the first-stage pressure storage tank, and the first energy conversion device is in communication with the second-stage pressure storage tank, and the first energy conversion device is used to convert the pressure energy released by the first flow stream into energy for supplying power to the user's power system; The second energy conversion device is arranged on the passage from the third-stage pressure storage tank to the first flow dividing component, and is used to convert the pressure energy released by the energy storage fluid output by the third-stage pressure storage tank into energy for supplying power to the user's power system; The energy storage system also includes at least one heat exchange device, each of the heat exchange devices includes two channels that are not connected to each other, the two channels of each heat exchange device are respectively connected in series in the first heat exchange circuit and the energy storage circuit, and each heat exchange device is used to exchange heat between fluids of different circuits flowing in the two channels of the heat exchange device.

2. The energy storage system according to claim 1, characterized in that Also includes: A fourth-stage pressure storage tank, wherein the energy storage fluid outputted from the third-stage pressure storage tank is further pressurized by renewable energy and flows to the fourth-stage pressure storage tank; a second flow splitting component, used for splitting the energy storage fluid outputted from the fourth-stage pressure storage tank to obtain a third flow stream flowing to the third-stage pressure storage tank and a fourth flow stream flowing to the second energy conversion device, and adjusting the ratio of the third flow stream to the fourth flow stream according to the power demand of the user power system; The third energy conversion device is arranged on the passage from the fourth-stage pressure storage tank to the second diversion component, and is used for converting the pressure energy released by the energy storage fluid output by the fourth-stage pressure storage tank into energy for supplying power to the user's power system.

3. The energy storage system according to claim 1, characterized in that The first heat exchange circuit includes a heat collection device for collecting thermal energy; in the at least one heat exchange device, at least one heating device is included for heating the energy storage fluid using the thermal energy provided by the heat collection device, and the channels of each heating device connected in series in the energy storage circuit are arranged on the passage flowing into any energy conversion device.

4. The energy storage system according to claim 3, characterized in that The first heat exchange circuit also includes an underground heat storage device for recovering the thermal energy.

5. The energy storage system according to claim 3, characterized in that The heat collection device includes a solar heat collection device and / or a geothermal heat collection device.

6. The energy storage system according to claim 1, characterized in that The energy storage system also includes a second heat exchange circuit, which includes a cold collection device for collecting cold energy; in the at least one heat exchange device, at least one cooling device is included for cooling the energy storage fluid using the cold energy provided by the cold collection device, and the channels of each cooling device connected in series in the energy storage circuit are arranged on the passage flowing out of any energy conversion device.

7. The energy storage system according to claim 1, characterized in that The energy storage circuit also includes: A plurality of heat recovery devices, each of which includes two channels that are not connected to each other, the two channels in each of the heat recovery devices are connected in series in the energy storage circuit, the flow direction of one channel in each of the heat recovery devices is from the Nth level pressure storage tank to the N-1th energy conversion device, and the flow direction of the other channel in each of the heat recovery devices is from the N-1th level pressure storage tank to the N-1th energy conversion device, and N is a positive integer greater than 1.

8. The energy storage system according to claim 1, characterized in that The renewable energy is wind and photovoltaic energy, and the energy storage system further comprises: A plurality of wind and photovoltaic power hydraulic pumps, each of which is arranged on an output passage of each pressure storage tank except the highest pressure storage tank, and is used to pressurize the energy storage fluid based on wind and photovoltaic power.

9. The energy storage system according to claim 1, characterized in that The energy storage system further comprises: A throttle valve is arranged on the output passage of each storage tank, and each throttle valve is used to adjust the pressure of the energy storage fluid output by the corresponding storage tank.

10. A control method for an energy storage system, characterized in that: The method is applied to the energy storage system according to any one of claims 1 to 9, and the method comprises: Determine the ratio of the two streams flowing out of each flow splitting component according to the power demand of the user's power system; Control each of the flow diversion components to adjust according to the determined ratio.

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