CN119508012A

CN119508012A - Energy storage system and control method thereof

Info

Publication number: CN119508012A
Application number: CN202411486014.9A
Authority: CN
Inventors: 张信荣; 方瑾嵘; 郑秋云; 刘佳
Original assignee: Peking University
Current assignee: Peking University
Priority date: 2024-10-23
Filing date: 2024-10-23
Publication date: 2025-02-25

Abstract

The present application discloses an energy storage system and a control method thereof, wherein 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; a first energy conversion device, a second energy conversion device, a first flow diversion component, a first-stage pressure storage tank, a second-stage pressure storage tank and a third-stage pressure storage tank are connected to each other and arranged in the energy storage circuit; the energy storage system further comprises at least one heat exchange device; in an embodiment of the present application, the high-pressure energy storage fluid of the third-stage pressure storage tank is divided into a first flow stream and a second flow stream by the first flow diversion component, the first flow stream is used to do work to supply power to a user's power system, the second flow stream that does not do work is recovered by the second-stage pressure storage tank, and the ratio of the first flow stream to the second flow stream is adjusted according to the demand of the user's power system, thereby improving the energy utilization efficiency in the energy storage system.

Description

Energy storage system and control method thereof

Technical Field

The application relates to the technical field of energy, in particular to an energy storage system and a control method thereof.

Background

Because renewable energy generating capacity is irregular and is difficult to match with peak-valley time periods of power demand of a user power utilization system, in order to store surplus energy of renewable energy, some energy storage systems exist in related technologies, fluids such as air, carbon dioxide and the like are used as energy storage media, and energy storage and release are realized through pressure change of the energy storage media. However, in the compressed gas energy storage system in the related art, when the peak-valley period of the electric power of the user power system is adapted, the flow output by the storage tank is regulated so as to regulate the amount of energy released. However, the output of the energy storage system is unstable, so that the performance of key components such as a compressor, a turbine and the like is deteriorated, the service life of the key components is shortened, and the energy utilization efficiency and the service life of the energy storage system are reduced.

Disclosure of Invention

The present application aims to solve at least the above-mentioned shortcomings of the prior art by providing an energy storage system and a control method thereof.

The embodiment of the application provides an energy storage system, which comprises an energy storage loop and a first heat exchange loop, wherein the energy storage loop is communicated with energy storage fluid, and the first heat exchange loop is communicated with heat exchange fluid;

The energy storage loop is internally provided with a first energy conversion device, a second energy conversion device, a first shunt assembly, a first-stage pressure storage tank, a second-stage pressure storage tank and a third-stage pressure storage tank which are communicated;

The energy storage fluid output by the first-stage pressure storage tank flows to the second-stage pressure storage tank after being pressurized by renewable energy sources, and the energy storage fluid output by the second-stage pressure storage tank flows to the third-stage pressure storage tank after being pressurized by renewable energy sources;

The first diversion component is used for diverting the energy storage fluid output by the third-stage pressure storage tank to obtain a first flow which flows to the first-stage pressure storage tank and a second flow which flows to the second-stage pressure storage tank, and adjusting the proportion of the first flow to the second flow according to the electricity consumption requirement of a user electricity consumption system;

The first energy conversion device is arranged on a passage of the first diversion component, which flows to the first-stage pressure storage tank, and is communicated with the second-stage pressure storage tank, and the first energy conversion device is used for converting pressure energy released by the first flow into energy for supplying power to the user power utilization system;

the second energy conversion device is arranged on a passage of the third-stage pressure storage tank, which flows to the first diversion assembly, and is used for converting pressure energy released by the energy storage fluid output by the third-stage pressure storage tank into energy for supplying power to the user power utilization system;

The energy storage system further comprises at least one heat exchange device, each heat exchange device comprises two channels which are not communicated with 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 for exchanging heat of fluid of different circuits flowing in the two channels of the heat exchange device.

Optionally, the system further comprises:

The energy storage fluid output by the third-stage pressure storage tank flows to the fourth-stage pressure storage tank after being pressurized by renewable energy sources;

The second flow dividing assembly is used for dividing the energy storage fluid output by the fourth-stage pressure storage tank to obtain a third flow which flows to the third-stage pressure storage tank and a fourth flow which flows to the second energy conversion device, and adjusting the proportion of the third flow to the fourth flow according to the electricity consumption requirement of the user electricity consumption system;

and the third energy conversion device is arranged on a passage of the fourth-stage pressure storage tank, which flows to the second flow dividing assembly, and is used for converting pressure energy released by the energy storage fluid output by the fourth-stage pressure storage tank into energy for supplying power to the user power utilization system.

Optionally, the first heat exchange loop comprises a heat collecting device for collecting heat energy, and the at least one heat exchange device comprises at least one heating device for heating the energy storage fluid by using the heat energy provided by the heat collecting device, and a channel of each heating device connected in series in the energy storage loop is arranged on a channel flowing into any energy conversion device.

Optionally, the first heat exchange loop further comprises an underground heat storage device for recovering the heat energy.

Optionally, the heat collecting device comprises a solar heat collecting device and/or a geothermal heat collecting device.

Optionally, the energy storage system further comprises a second heat exchange loop, wherein the second heat exchange loop comprises a cold collecting device for collecting cold energy, at least one cooling device for cooling the energy storage fluid by using the cold energy provided by the cold collecting device is arranged in the at least one heat exchange device, and a channel, wherein the cooling devices are connected in series in the energy storage loop, is arranged on a channel flowing out of any energy conversion device.

Optionally, the energy storage loop further includes:

the energy storage device comprises a plurality of heat recovery devices, wherein each heat recovery device comprises two channels which are not communicated with each other, the two channels in each heat recovery device are connected in series in the energy storage loop, the flow direction of one channel in each heat recovery device is from an N-th pressure storage tank to an N-1 energy conversion device, the flow direction of the other channel in each heat recovery device is from the N-1 pressure storage tank to the N-1 energy conversion device, and N is a positive integer greater than 1.

Optionally, the renewable energy source is wind-solar electric energy, and the energy storage system further comprises:

And a plurality of wind-solar energy hydraulic pumps, each of which is arranged on an output passage of each of the pressure tanks except the highest pressure tank, for pressurizing the energy storage fluid based on wind-solar energy.

Optionally, the energy storage system further comprises:

and the throttle valves are arranged on the output passages of the storage tanks and are used for adjusting the pressure of the energy storage fluid output by the corresponding storage tanks.

The embodiment of the application also provides a control method of the energy storage system, and the method is applied to the energy storage system provided by any technical scheme of the embodiment of the application, and comprises the following steps:

determining the proportion of two streams flowing out of each split component according to the electricity consumption requirement of a user electricity consumption system;

And controlling each flow dividing assembly to adjust according to the determined proportion.

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

The energy storage system comprises an energy storage loop through which energy storage fluid flows and a first heat exchange loop through which heat exchange fluid flows, wherein the energy storage loop is internally provided with a first energy conversion device, a second energy conversion device, a first shunt assembly, a first stage pressure storage tank, a second stage pressure storage tank and a third stage pressure storage tank which are communicated, the energy storage fluid output by the first stage pressure storage tank flows to the second stage pressure storage tank after being pressurized by renewable energy sources, the energy storage fluid output by the second stage pressure storage tank flows to the third stage pressure storage tank after being pressurized by renewable energy sources, the first shunt assembly is used for shunting the energy storage fluid output by 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, the proportion of the first flow stream and the second flow stream is adjusted according to the electricity consumption requirement of a user electricity consumption system, the first energy conversion device is arranged on a channel of the first shunt assembly, the first energy conversion device is communicated with the second stage pressure storage tank, the first energy conversion device is used for converting pressure energy released by the first flow stream into energy consumed by the user electricity, the second energy conversion device flows to the heat exchange device, the first heat exchange device is arranged on each heat exchange loop, and the heat exchange device is not connected to the first heat exchange device and the second heat exchange device is connected to the heat exchange loop through at least two heat exchange channels, and the first heat exchange device is connected to the first heat exchange device, and the heat exchange device is used for releasing heat exchange fluid flow, and the heat exchange fluid flows through the heat exchange device.

According to the embodiment of the application, the high-pressure energy storage fluid of the third-stage pressure storage tank is divided into the first flow and the second flow through the first flow dividing component, the first flow is used for acting to supply power to the user power utilization system, the second flow which does not act is recovered through the second-stage pressure storage tank, the proportion of the first flow to the second flow is regulated according to the user power utilization system requirement, and the energy utilization efficiency in the energy storage system is improved.

The foregoing description is only an overview of the present application, and is intended to provide a better understanding of the technical means of the present application, as it is embodied in the present specification, and is intended to provide a better understanding of the above and other objects, features and advantages of the present application, as it is embodied in the following description.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:

Fig. 1 is a schematic structural diagram of an energy storage system according to an embodiment of the present application;

Fig. 2 is a schematic diagram of a second structure of an energy storage system according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of a first heat exchange circuit in an energy storage system according to an embodiment of the present application;

Fig. 4 is a schematic structural diagram of a second heat exchange circuit in an energy storage system according to an embodiment of the present application;

FIG. 5 is a schematic diagram of an energy storage system according to an embodiment of the present application in a first mode of a power release phase;

FIG. 6 is a schematic diagram of a second mode of an energy storage system in a power release phase according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a third embodiment of an energy storage system in a third mode of energy release;

FIG. 8 is a schematic diagram of a structure of an energy storage system according to an embodiment of the present application in a fourth mode of the energy release phase;

Fig. 9 is a schematic structural diagram of an energy storage system in a mode five of an energy release stage according to an embodiment of the present application;

FIG. 10 is a schematic diagram of an energy storage system according to an embodiment of the present application in a first energy storage phase mode;

FIG. 11 is a schematic diagram of a second energy storage system in a second energy storage phase mode according to an embodiment of the present application;

Fig. 12 is a schematic structural diagram of an energy storage system in a third energy storage phase mode according to an embodiment of the present application.

In the drawings, the list of partial reference numerals is as follows:

101. A third stage pressure tank 102, a throttle valve of the third stage pressure tank 103, a second stage preheater 104, a second stage regenerator 105, a second stage heater 106, a second energy conversion device 107, a first split flow component 1071, a first three-way valve 1072, a second three-way valve 108, a first stage reheater 109, a first energy conversion device 110, a first stage regenerator 111, a first stage cooler 112, a cold storage unit 113, a first stage pressure tank 114, a throttle valve of the first stage pressure tank 115, a first stage heater 116, a first stage hydraulic pump 117, a first stage preheater 118, a second stage pressure tank 119, a first throttle valve of the second stage pressure tank 120, a 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 heat collecting unit, 125, heat accumulating 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 regenerator, 132, third-stage heater, 133, third energy conversion device, 134, second shunt assembly, 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 accumulating device, 139, second buried heat accumulating device, 140, third buried heat accumulating device, 141, external cold source.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the application. Rather, they are merely examples of apparatus and methods consistent with aspects of the application as detailed in the accompanying claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.

It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, these information should not be limited by these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the application. The term "if" as used herein may be interpreted as "at..once" or "when..once" or "in response to a determination", depending on the context.

An embodiment of the present application provides an energy storage system, referring to fig. 1, that includes an energy storage circuit in which an energy storage fluid is circulated and a first heat exchange circuit in which a heat exchange fluid is circulated. The energy storage fluid flows in the direction indicated by the solid line with the arrow in fig. 1. The energy storage fluid is a fluid for storing energy through pressure, and can be liquid, gas or medium in a critical state or a supercritical state, alternatively, the energy storage fluid can be carbon dioxide, and according to different temperatures and pressures, different parts of the carbon dioxide in the energy storage loop can be in different stages in the liquid, gas or supercritical state.

The energy storage loop is provided with a first energy conversion device 109, a second energy conversion device 106, a first diversion assembly 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 communicated.

The energy storage fluid output from the first stage pressure storage tank 113 flows to the second stage pressure storage tank 118 after being pressurized by the renewable energy source, and the energy storage fluid output from the second stage pressure storage tank 118 flows to the third stage pressure storage tank 101 after being pressurized by the renewable energy source. Alternatively, the pressurized module may be a hydraulic pump and the renewable energy source may use wind energy and/or light energy, which after conversion to electrical energy drives the hydraulic pump to pressurize the energy storage fluid. The renewable energy source is utilized to pressurize the energy storage fluid, the renewable green energy source can be converted into pressure energy, the renewable energy source is stored in a mode of storing the pressure energy of the energy storage fluid, and the environmental protection effect of the energy storage system is improved. It will be appreciated that in addition to the three-stage pressure storage tank, more stages of pressure storage tanks may be provided in the energy storage system according to the embodiment of the present invention, for example, referring to fig. 2, the energy storage system may further include a fourth-stage pressure storage tank 128, where the energy storage fluid output from the third-stage pressure storage tank 101 flows to the fourth-stage pressure storage tank 128 after being pressurized by the renewable energy source.

For example, the means for pressurizing the energy storage fluid in the energy storage system may be wind-solar energy hydraulic pumps using wind-solar energy, each wind-solar energy hydraulic pump being arranged on the output path of each pressure tank except the highest pressure tank for pressurizing the energy storage fluid based on wind-solar energy. Referring to fig. 1, the energy storage system may include a first stage hydraulic pump 116 and a second stage hydraulic pump 123. Referring to FIG. 2, the energy storage system may also include a third stage hydraulic pump 127.

The pressures of the third-stage pressure tank 101, the second-stage pressure tank 118 and the first-stage pressure tank 113 are reduced, which is equivalent to a high-pressure tank, a medium-pressure tank and a low-pressure tank, respectively, and the specific pressure value design of each pressure tank can be determined according to the actual situation, which is not limited in this embodiment. The energy of the renewable energy sources is used for providing pressure for the energy storage fluid output by the low-pressure storage tank and the medium-pressure storage tank, and the renewable energy sources can be converted into the pressure energy of the energy storage fluid so as to be stored, and the pressure energy is converted into electric energy when a power supply requirement exists in the electric system for a user.

Alternatively, the conversion process may be to convert the pressure energy into mechanical energy and then to convert the mechanical energy into electrical energy. For example, the pressure energy of the stored energy fluid may be converted to mechanical energy by a pneumatic turbine and then to electrical energy by a generator.

First energy conversion device 109 is disposed on a path of first diversion assembly 107 to first stage pressure storage tank 113, and first energy conversion device 109 communicates with second stage pressure storage tank 118, first energy conversion device 109 being configured to convert pressure energy released by the first stream into energy that is used to power the consumer's electrical system. The first energy conversion device 109 may be a turbine device for converting pressure energy of the stored energy fluid into mechanical energy, which may then be used to perform work and convert the mechanical energy into electrical energy for powering the consumer electrical system. For example, the turbine device may be a steam turbine, an expander, or the like.

The first diversion component 107 is configured to divert the energy storage fluid output from the third stage pressure storage tank 101 to obtain a first flow that flows to the first stage pressure storage tank 113 and a second flow that flows to the second stage pressure storage tank 118, and adjust the ratio of the first flow to the second flow according to the power consumption requirement of the user power consumption system. The first flow does work through the first energy conversion device 109 to supply power to the user power system, and the second flow which does not do work is recovered through the second-stage pressure storage tank 118, so that the energy waste of the collected renewable energy sources is reduced, the pressure energy which does not do work is recovered into the second-stage pressure storage tank 118, and the energy utilization efficiency of the energy storage system is improved. In addition, the flow rate of the outlet of the third-stage pressure storage tank 101 does not need to be adjusted, so that the output of the third-stage pressure storage tank 101 can be kept stable, the energy storage fluid is conveyed outwards through a constant flow, and the ratio of the first flow to the second flow is adjusted by the first flow dividing component 107 according to the peak-valley condition of the power utilization system of the user. Referring to fig. 1, first split assembly 107 may include a first three-way valve 1071 and a second three-way valve 1072.

A second energy conversion device 106 is disposed in the path of the third stage pressure tank 101 to the first diversion assembly 107 for converting the pressure energy released by the stored energy fluid output from the third stage pressure tank 101 into energy for powering the consumer electrical system. By arranging two energy conversion devices at the outlet of the third-stage pressure storage tank 101 and the outlet of the first flow of the first diversion component 107 respectively, the pressure energy of the energy storage fluid can be fully converted, the energy release is effectively improved, and the conversion efficiency of the pressure energy is improved.

The energy storage system further comprises at least one heat exchange device, each heat exchange device comprises two channels which are not communicated with 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 channels connected in series in the first heat exchange circuit circulate heat exchange fluid, the channels connected in series in the energy storage circuit circulate energy storage fluid, and each heat exchange device is used for exchanging heat of the fluid of different circuits circulated in the two channels of the heat exchange device.

It will be appreciated that in the case of the energy storage system provided by the embodiment of the present invention further comprising a fourth stage pressure tank, the energy storage system further comprises a second splitting component 134, configured to split the energy storage fluid output from the fourth stage pressure tank 128 to obtain a third flow stream flowing to the third stage pressure tank 101 and a fourth flow stream flowing to the second energy conversion device 106, and adjust the ratio of the third flow stream and the fourth flow stream according to the power consumption requirement of the user power consumption system. Referring to fig. 2, the second flow dividing assembly 134 may include a third three-way valve 1341 and a fourth three-way valve 1342.

And a third energy conversion device 133, disposed on a path of the fourth stage pressure storage tank 128 flowing to the second shunt assembly 134, for converting pressure energy released by the energy storage fluid output from the fourth stage pressure storage tank 128 into energy for supplying power to the user electrical system.

Similarly, the embodiment of the invention can also be provided with more stages of pressure storage tanks, which cannot be used for exhaustion. Through addding multistage pressure storage tank, can create more careful grade difference for the storage, the utilization and the recovery of energy, and then show the availability factor of promoting energy.

Optionally, the energy storage system further comprises a throttle valve provided on the output passage of each tank, each throttle valve for regulating the pressure of the storage fluid output by the corresponding tank, with reference to the throttle valve of each stage of pressure tanks in fig. 1 and 2. The throttle valve is used for stabilizing the pressure of the energy storage fluid output by each pressure storage tank, so that the pressure stability of the energy storage fluid output by the pressure storage tank is improved, and the pressure balance capacity of the whole energy storage loop is improved. Referring to fig. 3, a throttle valve 129 of the fourth stage pressure tank is also included.

Optionally, the energy storage loop also comprises a plurality of heat recovery devices, each heat recovery device comprises two channels which are not communicated with each other, the two channels in each heat recovery device are connected in series in the energy storage loop, the flow direction of one channel in each heat recovery device is from the N-th pressure storage tank to the N-1 energy conversion device, the flow direction of the other channel in each heat recovery device is from the N-1 pressure storage tank to the N-1 energy conversion device, and N is a positive integer greater than 1. Referring to fig. 1, the plurality of regeneration devices includes a first stage regenerator 110 and a second stage regenerator 104. Referring to fig. 2, the plurality of regeneration devices may further include a third stage regenerator 131.

The heat of the energy storage fluid flowing out of each energy conversion device can be recovered through the heat recovery device, and the energy storage fluid flowing into the energy conversion device is heated by utilizing the heat energy, so that the heat energy of the energy storage fluid is fully utilized, and the heat energy utilization efficiency is improved.

Alternatively, a heat collecting device for collecting heat energy may be included in the first heat exchange circuit, and the heat collecting device may collect heat, for example, may collect solar energy, geothermal energy, or the like. At least one heat exchange device comprises at least one heating device for heating the energy storage fluid by using the heat energy provided by the heat collection device, and a channel of each heating device connected in series in the energy storage loop is arranged on a passage flowing into any energy conversion device. Optionally, referring to fig. 1, the heating device in the first heat exchange circuit may include a first stage heater 115 and a second stage heater 105, optionally the heat collecting device includes a solar heat collecting device and/or a geothermal heat collecting device. Referring to fig. 1, the heat collecting device is a solar heat collecting unit 124. The solar heat collection unit 124 is used to convert solar energy into thermal energy of a heat exchange fluid. Heating the energy storage fluid using the green energy collected by the solar heat collection unit 124 may improve the environmental protection effect of the energy storage system. Referring to fig. 2, for the added fourth stage pressure tank 128, the heating device in the first heat exchange circuit may also include a third stage heater 132.

Further, referring to fig. 1, the heating means in the first heat exchange circuit may further comprise a first stage preheater 117 and a second stage preheater 103. Taking the second-stage preheater 103 as an example of the preheater, the second-stage preheater 103 can raise the temperature of the energy storage fluid output by the third-stage pressure storage tank 101, which is favorable for converting the liquid energy storage fluid output by the third-stage pressure storage tank 101 into the supercritical state or gaseous energy storage fluid, so that the energy conversion device connected subsequently can conveniently utilize the pressure energy of the energy storage fluid to apply work, and the energy conversion efficiency of the energy conversion device is improved. Referring to fig. 2, for the added fourth stage pressure tank 128, the heating device in the first heat exchange circuit may also include a third stage preheater 130.

Optionally, in the at least one heating device, a reheating device may be further included. Referring to fig. 1, the reheating device includes a first stage reheater 108 provided on a passage flowing into the first energy conversion device 109 to heat the energy storage fluid flowing into the first energy conversion device 109. Referring to fig. 2, the reheat device may further include a second stage reheater 135 provided in 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 reheating device can improve the energy conversion efficiency of the energy conversion device.

Optionally, the first heat exchange circuit further comprises an underground heat storage device for recovering heat energy, so as to store the redundant heat energy in the first heat exchange circuit.

Optionally, the energy storage system may further comprise a second heat exchange circuit, the first heat exchange circuit and the second heat exchange circuit being non-communicating, the heat exchange fluid in the second heat exchange circuit being used as a cold source for cooling the energy storage fluid in the energy storage circuit. The second heat exchange loop comprises a cold collecting device for collecting cold energy, wherein the cold collecting device can collect cold energy, and the cold collecting device can comprise air, water and liquid natural gas of a building. At least one heat exchange device comprises at least one cooling device for cooling the energy storage fluid by using the cold energy provided by the cold collecting device, and channels, which are connected in series in the energy storage loop, of each cooling device are arranged on a channel flowing out of any energy conversion device. Referring to fig. 1, the cold collecting device includes a first stage cooler 111 and a second stage cooler 120, and referring to fig. 2, the cold collecting device may further include a third stage cooler 136. The cold energy collected by the cold collecting 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, so that the volume of the energy storage fluid is compressed, the pressure of the energy storage fluid is improved, and the efficiency of the energy storage fluid for storing pressure energy is improved. The effect of the cooler cooling the stored energy fluid is illustrated with respect to the second stage cooler 120, which helps to convert the stored energy fluid in the gaseous or supercritical state back to the liquid state, thereby improving the energy storage efficiency of the second stage pressure storage tank 118.

Through the first heat exchange loop, the temperature of the energy storage fluid circulating in the energy storage system can be adjusted, the control of switching between different states of the energy storage fluid such as gas state, liquid state and supercritical state is realized, the temperature of the energy storage fluid can be adjusted through the position of the heat exchange device specifically arranged in the energy storage loop, and the energy release efficiency and the energy storage efficiency of the energy storage fluid are improved.

Referring to fig. 3, a specific implementation of a first heat exchange circuit in an energy storage system according to the embodiment of the present invention is provided in the embodiment of fig. 2. The first heat exchange circuit is the circuit shown in dashed lines in fig. 3, with the heat exchange fluid flowing in the direction indicated by the dashed lines with arrows in fig. 3. The first heat exchange circuit corresponds to the cycle of the heat storage unit 125. The first heat exchange circuit includes three circuits as in fig. 3, and includes a plurality of buried heat storage apparatuses, a first buried heat storage apparatus 138, a second buried heat storage apparatus 139, and a third buried heat storage apparatus 140. The three loops are described as follows:

Referring to fig. 3, the first circuit includes a heat storage unit 125 to collect heat of a solar heat collection unit 124, and then release a working medium (water, oil or others) to a third stage heater 132 as a heat source, wherein after the working medium is cooled once, optionally, surplus heat can be stored in a first buried heat storage device 138, and the working medium is cooled twice, then passes through a second stage heater 105 as a heat source of the second stage heater 105, and optionally, the surplus heat is stored in the first buried heat storage device 138 for three times, and then passes through the first stage heater 115 as a heat source of the first stage heater, and finally, the surplus heat is stored in soil through the first buried heat storage device 138, and finally, returns to the solar heat collection unit 124 for heating. The circuit buried heat storage device is in the heat storage process.

Referring to fig. 3, the second circuit includes a working medium in a tank (specifically, a water tank 137) for storing the working medium (i.e., a heat exchange fluid, water or others), after entering the second buried heat storage device 139, the working medium is first warmed up, enters the third-stage preheater 130 as a heat source, is first cooled down, then enters the second buried heat storage device 139, is second warmed up, then enters the second-stage preheater 103 as a heat source, is second cooled down, then enters the second buried heat storage device 139, is third warmed up, finally enters the first-stage preheater as a heat source, is third cooled down, and finally returns to the water tank 137. The circuit buried heat storage device is in a heat release process.

Referring to fig. 3, the third circuit includes a heat storage unit 125 that collects heat from the solar heat collection unit 124, then releases the working medium (water, oil, or other) that passes through the second stage reheater 135 and the first stage reheater 108 in sequence as a heat source, and optionally then enters a third buried heat storage unit 140, stores the excess heat in soil, and finally returns to the solar heat collection unit 124 for heating. The circuit buried heat storage device is in the heat storage process.

It should be noted that the first buried heat storage device 138 in the buried heat storage device is exchanged with the second buried heat storage device 139 after a certain period of time has elapsed/when the heat storage is nearly saturated, or the second buried heat storage device 139 is released after a certain period of time/when the heat storage is nearly saturated, i.e., the first buried heat storage device 138 is connected to the second circuit, the second buried heat storage device 139 is connected to the first circuit, and the third buried heat storage device 140 may be provided as a backup heat source to the first circuit or other heat-consuming components such as a heat pump.

Referring to fig. 4, in the embodiment of the present invention, the heat exchange fluid flows along the direction of the dotted arrow, and the second heat exchange circuit may be a cold source circuit, where the cold storage unit 112 releases the working medium (i.e., the heat exchange fluid) and sequentially passes through the first stage cooler 111, the second stage cooler 120, and the third stage cooler 136 to serve as a cold source for cooling the energy storage fluid. After the working medium is warmed up, the working medium may be cooled by the external cooling source 141 and stored in the cold storage unit 112.

The technical scheme of the energy storage system provided in this embodiment applied in a specific application scenario is described in detail below with reference to fig. 1.

With the improvement of industrialization degree and the rapid development of economy, global energy demands are increasing, and excessive emission of greenhouse gas carbon dioxide is brought about. To solve environmental problems caused by excessive carbon dioxide emissions, global energy structures are being inclined toward clean energy. However, renewable energy sources such as wind power and solar energy are intermittent, which means that surplus power which may be generated by the renewable energy sources cannot be utilized, and at the same time, due to the inherent characteristics of the renewable energy sources and the mismatch between the renewable energy source generation and a user power utilization system, the rejection rate of green power is high, and only a part of renewable energy source generation can be supplied to a power terminal. In addition to this, the application of energy storage technology is therefore an effective solution to the above-mentioned problems.

At present, a plurality of mature energy storage technologies are put into commercial use, such as pumped storage, compressed gas storage and the like. The pumped storage is higher than the compressed gas storage in energy storage efficiency, but is difficult to be widely applied because the pumped storage is limited by geographical environment, and the compressed gas storage is currently two types, namely compressed air storage and compressed carbon dioxide storage, and the two types of compressed gas storage generally have the problems of low energy storage density and the like, but the excellent thermophysical heat of carbon dioxide and the proper critical point thereof enable the carbon dioxide to be more easily stored in a supercritical state or in a liquid state than air, so that the energy storage density of a compressed energy storage system taking carbon dioxide as an energy storage working medium is superior to that of a system taking the carbon dioxide as the working medium. At present, the research on a liquid carbon dioxide energy storage system mainly aims at designing a better system circulation, evaluating the system performance from the aspects of economy and thermodynamics, and the research is directed at the problems of coupling of liquid carbon dioxide energy storage and renewable energy sources and energy storage and release regulation of the liquid carbon dioxide energy storage system.

The embodiment provides an energy storage system for storing energy by utilizing liquid carbon dioxide. The system comprises a liquid carbon dioxide energy storage and release unit, a solar heat collection unit 124, a heat storage unit 125, a soil source heat storage unit 125 and a cold storage unit 112. The system aims at optimizing the circulation of the energy storage system, provides a new peak regulation strategy of the power utilization system of the user by additionally arranging the pressure storage tank of the middle stage, and also realizes the multistage compression and multistage expansion of the liquid carbon dioxide. By using the photoelectric hydraulic pump in the energy storage system, the heat exchange loss of vaporization when the liquid carbon dioxide energy storage system releases energy is reduced. Meanwhile, the solar heat collection unit 124, the heat storage unit 125, the cold storage unit 112 and the soil source heat storage unit 125 are combined, corresponding heat energy (comprising heat energy and cold energy) is provided for the liquid carbon dioxide energy storage and release unit, the purpose of cold storage and heat storage is achieved, and the heat energy utilization efficiency of the energy storage system is improved through gradient utilization of the heat energy.

The manner in which the energy storage system including the three-stage pressure storage tank shown in FIG. 1 operates is described below. The energy release stage comprises five working modes shown in fig. 5-9, and the energy storage stage comprises three working modes shown in fig. 10-12.

Referring to fig. 5, the energy release phase mode one:

The third-stage pressure storage tank 101 releases a liquid energy storage medium, and the liquid energy storage medium sequentially passes through the second-stage preheater 103, the second-stage regenerator 104 and the second-stage heater 105 through pipelines, is heated and gasified to be in a gaseous state or a supercritical state, then enters a steam turbine (equivalent to the second energy conversion device 106) to do work, enters the second-stage regenerator 104, and is cooled into a liquid state by the second-stage cooler 120, and enters the second-stage pressure storage tank 118.

Referring to fig. 6, energy release phase mode two:

The third-stage pressure storage tank 101 releases energy storage medium, the energy storage medium sequentially passes through the second-stage preheater 103, the second-stage regenerator 104 and the second-stage heater 105 to be gasified to a gaseous state or a supercritical state through pipelines, the energy storage medium enters a steam turbine to do work and then enters a flow dividing valve (a first three-way valve 1071), one flow flowing out of the flow dividing valve is cooled to be liquid through the second-stage regenerator 104 and the second-stage cooler 120 in sequence and then enters a second-stage pressure storage tank 118 to be stored, the other flow flowing out of the flow dividing valve is heated through the first-stage reheater 108 and then enters an expansion machine (equivalent to the first energy conversion device 109) to do work and then enters the first-stage pressure storage tank 113 to be stored after being liquefied through the second-stage cooler 120, and the proportion of the flow to the second-stage pressure storage tank 118 and the first-stage pressure storage tank 113 is adjusted according to the power consumption requirement of a user.

Referring to fig. 7, energy release phase mode three:

The third-stage pressure storage tank 101 releases energy storage medium, and the energy storage medium sequentially passes through the second-stage preheater 103, the second-stage heat regenerator 104 and the second-stage heater 105 to be gasified to a gaseous state or a supercritical state through pipelines, enters a steam turbine to do work, is heated by the first-stage heat regenerator 108 and then enters an expansion machine to do work, and then sequentially passes through the second-stage heat regenerator 104 and the first-stage cooler 111 to be cooled to be liquid, and then enters the first-stage pressure storage tank 113.

Referring to fig. 8, energy release phase mode four:

Simultaneously, the second-stage pressure storage tank 118 releases the energy storage medium to be gasified to a gaseous state or a supercritical state through the pipeline in sequence through the first-stage preheater 117, the first-stage regenerator 110 and the first-stage heater 115, enters a flow dividing valve, is mixed with the energy storage medium released by the third-stage pressure storage tank 101 through the flow dividing valve, is heated through the first-stage reheater 108 and then enters an expander to do work, and a flow at an outlet of the expander sequentially passes through the second-stage regenerator 104, the first-stage regenerator 110 and the first-stage cooler 111, is cooled to be liquid and then enters the first-stage pressure storage tank 113 for storage.

Referring to fig. 9, energy release phase mode five:

The second-stage pressure storage tank 118 releases energy storage medium, and the energy storage medium is vaporized to a gaseous state or a supercritical state through the first-stage preheater 117, the first-stage regenerator 110 and the first-stage heater 115 in sequence through pipelines, then enters an expander to apply work after being heated by the first-stage reheater 108, and flows at the outlet of the expander are cooled to be liquid through the first-stage regenerator 110 and the first-stage cooler 111 in sequence and then enter the first-stage pressure storage tank 113 for storage.

Referring to fig. 10, in the first energy storage stage mode, the first-stage pressure storage tank 113 releases the energy storage medium, passes through the throttle valve 114 of the first-stage pressure storage tank 113, enters the first-stage hydraulic pump 116, drives the first-stage hydraulic pump 116 by using redundant wind and light electricity, pressurizes the energy storage medium, and enters the second-stage pressure storage tank 118 for storage.

Referring to fig. 11, in the second energy storage stage mode, the second stage pressure storage tank 118 releases the energy storage medium, passes through the throttle valve of the second stage pressure storage tank 118, enters the second stage hydraulic pump 123, drives the second stage hydraulic pump 123 by using redundant wind and light electricity, pressurizes the energy storage medium, and enters the third stage pressure storage tank 101 for storage.

Referring to fig. 12, in the energy storage stage mode three, the first-stage pressure storage tank 113 releases the energy storage medium, passes through the throttle valve 114 of the first-stage pressure storage tank 113, enters the first-stage hydraulic pump 116, drives the first-stage hydraulic pump 116 by using redundant wind and light electricity, pressurizes the energy storage medium, passes through the second-stage hydraulic pump 123, pressurizes the energy storage medium, and enters the third-stage pressure storage tank 101 for storage.

Further, the structure of the energy storage system shown in fig. 1 and its operation principle will be described in detail:

Referring to fig. 1, the liquid carbon dioxide energy storage and release unit includes a third stage pressure tank 101, a throttle valve 102 of the third stage pressure tank 101, a second energy conversion device 106 (which may be a steam turbine, in particular), a first diversion component 107 (which may be a three-way valve, in particular), a first energy conversion device 109 (which may be an expander, in particular), a first stage pressure tank 113, a throttle valve 114 of the first stage pressure tank 113, a first stage hydraulic pump 116, a second stage pressure tank 118, a first throttle valve 119 of the second stage pressure tank 118, a second throttle valve 121 of the second stage pressure tank 118, and a second stage hydraulic pump 123.

The energy storage system also includes a high pressure stage carbon dioxide vaporization heating unit, specifically including a second stage preheater 103 and a third stage heater 132. The energy storage system also includes a medium pressure stage carbon dioxide vaporization heating unit, specifically including a first stage preheater 117 and a second stage heater 105.

In the structure of the energy storage system shown in fig. 1, the specific connection relationship of the components includes:

The outlet of the third-stage pressure storage tank 101 is communicated with the high-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 diversion component 107 through pipelines. One flow of the first diversion assembly 107 is sequentially connected with the inlet of the second-stage pressure storage tank 118 through the high-temperature side of the second-stage regenerator 104 and the high-temperature side of the second-stage cooler 120 by pipelines. The outlet of the second-stage pressure storage tank 118 is sequentially mixed with the other side flow of the first diversion assembly 107 through a 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 by pipelines. The mixed flow is connected with the inlet of the first-stage pressure storage tank 113 through a pipeline sequentially through the low-temperature side of the reheater, the first energy conversion device 109, the high-temperature side of the first-stage regenerator 110 and the high-temperature side of the first-stage cooler 111. The outlet of the first-stage pressure storage tank 113 is connected with the other inlet of the second-stage pressure storage tank 118 through a throttle valve 114 of the first-stage pressure storage tank 113 and a first-stage hydraulic pump 116 in sequence by pipelines. The other outlet of the second-stage pressure storage tank 118 is connected with the inlet of the third-stage pressure storage tank 101 through a pipeline sequentially through a second throttle valve 121 and a second-stage hydraulic pump 123 of the second-stage pressure storage tank 118. By adding a second stage pressure tank 118 between third stage pressure tank 101 and first stage pressure tank 113, the stored energy may be regulated by flow distribution of first split assembly 107. Alternatively, third stage pressure tank 101 can reach a minimum rated pressure at each energy release.

The energy storage system also comprises a shallow geothermal utilization unit, and specifically comprises a ground heat exchanger 122, wherein the ground heat exchanger 122 is formed by connecting a plurality of ground pipes in series. The outlet of the cold storage unit 112 is connected to the first stage cooler 111 through a pipe. The outlet of the solar heat collection unit 124 is connected with the heat storage unit 125 through a pipeline, one stream of the outlet of the heat storage unit 125 sequentially passes through 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 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 through pipelines, and the other stream of the outlet of the heat storage unit 125 is connected with the inlet of the solar heat collection unit 124 through the high temperature side of the reheater through a pipeline. The photo-thermal collected by the solar heat collection unit 124 is stored in the heat storage unit 125, and is connected with the buried pipe heat exchanger 122 after being released to the third-stage carbon dioxide vaporization heating unit. The heat exchange medium at the outlet of the solar heat collection unit 124 enters the heat storage unit 125, the heat exchange medium at the outlet of the heat storage unit 125 sequentially passes through 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 and the first-stage preheater 117 to be connected with the solar heat collection unit 124 through pipelines to form a circulation loop, and the heat exchange medium at the outlet of the heat storage unit 125 is connected with the solar heat collection unit 124 through a reheater through pipelines to form a two-circulation loop.

The working principle and specific operation process of the energy storage system provided by the embodiment are as follows:

In the energy storage stage, only the liquid carbon dioxide energy storage and release system unit comprising the multistage pressure storage tank works and is divided into two working conditions, namely a photoelectric sufficient working condition and a photoelectric insufficient working condition, wherein:

In the photoelectric full working condition, the outlet of the first-stage pressure storage tank 113 provides low-temperature low-pressure liquid carbon dioxide, the low-temperature low-pressure liquid carbon dioxide passes through the throttle valve 114 of the first-stage pressure storage tank 113 to reach a stable pressure and then enters the first-stage hydraulic pump 116, the first-stage hydraulic pump 116 pressurizes the liquid carbon dioxide under photoelectric driving to lower-temperature medium pressure and then enters the second-stage pressure storage tank 118 until the first-stage pressure storage tank 113 reaches a rated minimum pressure, meanwhile, the outlet of the second-stage pressure storage tank 118 provides low-temperature medium-pressure liquid carbon dioxide, the low-temperature medium-pressure liquid carbon dioxide passes through the second throttle valve 121 of the second-stage pressure storage tank 118 to reach the stable pressure and then enters the second-stage hydraulic pump 123, the second-stage hydraulic pump 123 pressurizes the liquid carbon dioxide under photoelectric driving to lower-temperature high-pressure and then enters the third-stage pressure storage tank 101 until the second-stage pressure storage tank 118 reaches the lowest rated pressure and at the same time the third-stage pressure storage tank 101 reaches the highest rated pressure.

When the photoelectricity is insufficient, the operation flow is the same as that of the photoelectricity sufficient condition, and the difference is that when the photoelectricity is insufficient, the first-stage hydraulic pump 116 is preferentially operated, the second-stage hydraulic pump 123 stops operating, and after the second-stage pressure storage tank 118 is ensured to reach the highest rated pressure, the first-stage hydraulic pump 116 and the second-stage hydraulic pump 123 are simultaneously operated.

In the energy release stage, the liquid carbon dioxide energy storage and release system unit comprising the multi-stage pressure storage tank is circulated as follows, the third-stage pressure storage tank 101 provides high-pressure low-temperature liquid carbon dioxide, after the high-pressure storage tank throttles to stable pressure, the liquid carbon dioxide absorbs heat of a heat transfer medium of the heat storage unit 125 through a low-temperature side of the second-stage preheater 103, the residual heat at an outlet of the second energy conversion device 106 is recovered through a low-temperature side of the second-stage regenerator 104, and then the liquid carbon dioxide is heated to a high-temperature supercritical state through a heat transfer medium of the heat storage unit 125 through the third-stage heater 132, and then the liquid carbon dioxide enters the second energy conversion device 106 to perform work and power generation. The medium temperature and medium pressure carbon dioxide gas at the outlet of the second energy conversion device 106 enters the first diversion assembly 107 to be split into two streams. The second flow passes through the high temperature side of the second-stage regenerator 104 through a pipeline, then enters the high temperature side of the second-stage cooler 120, enters the second-stage pressure storage tank 118, and is mixed with the low-temperature medium-pressure liquid carbon dioxide provided by the second-stage pressure storage tank 118, sequentially passes 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 to be heated into medium-temperature medium-pressure gaseous carbon dioxide, and then is added into the first flow. The first stream enters the reheater to be heated and then enters the first energy conversion device 109 to perform work. The flow of the two streams is controlled by the consumer electrical load, and when the electrical load is greater, more flow flows to the reheater. When the electrical load is smaller, more flow flows to the high temperature side of second stage regenerator 104. The low-pressure carbon dioxide after the outlet of the first energy conversion device 109 sequentially enters the high-temperature side of the first-stage regenerator 110 through a pipeline, and the high-temperature side of the first-stage cooler 111 enters the first-stage pressure storage tank 113, so that energy release is finished.

The solar heat collection unit 124 heats the heat transfer medium to a certain temperature and stores the heat transfer medium in the heat storage unit 125, in the energy release stage, the heat storage unit 125 releases the heat transfer medium, one stream sequentially enters 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 and the first-stage preheater 117 through pipelines to finally return to the solar heat collection unit 124 to form a first circulation loop, and the other stream enters the high temperature side of the reheater to finally return to the solar heat collection unit 124 to form a second circulation loop.

The embodiment provides an energy storage system, can couple geothermal energy, photo-thermal, wind-solar electricity, utilizes multistage liquid carbon dioxide pressure storage tank to carry out peak shaving, and this energy storage system has following characteristics:

1. The method can enable peak regulation to be more flexible, can enable the flow output by the storage tanks to be kept stable, ensures the thermodynamic properties of the compressor, the turbine and other parts, and reduces the risks of fatigue and damage of equipment;

2. When releasing energy, the heat of the storage tank is recovered by the heat regenerator, so that the energy utilization rate is improved;

3. the multi-stage expansion intermediate heating effectively improves the energy release;

4. The compression energy storage system is innovatively coupled with wind, light, electricity, light, heat and geothermal, so that the heat exchange temperature difference is reduced while the utilization rate of renewable energy sources is improved, and the energy cascade utilization is realized.

According to the technical scheme and the characteristics of the energy storage system, the energy storage system at least has the beneficial technical effects that wind-light electricity, light heat and shallow geothermal energy are combined with the liquid carbon dioxide energy storage system, heat exchange loss is reduced through heat cascade utilization, the utilization rate of renewable energy sources is improved, the combined utilization of wind-light electricity, light heat, geothermal energy and energy storage is realized, a novel peak regulation strategy of the liquid carbon dioxide energy storage system is provided through the addition of the intermediate pressure storage tank, and the peak regulation strategy can control the pressure of the carbon dioxide storage tank more flexibly.

The energy storage system provided by the embodiment can execute the peak regulation strategy according to the peak-valley condition of the user power utilization system, and can regulate energy storage and energy release, so that the energy waste is reduced. And the energy conversion efficiency in the system is improved through the heat regenerative device, the multistage expansion and the system structure heated before the expansion. The system can absorb the pressure energy of photoelectric storage, and simultaneously can provide the heat required in the energy storage system by storing and utilizing photo-thermal energy and geothermal energy, thereby reducing the heat exchange temperature difference and improving the heat utilization rate.

The embodiment of the application also provides a control method of the energy storage system, which can be applied to control the energy storage system provided by any technical scheme of the embodiment of the application, and specifically comprises the following steps:

And secondly, controlling each flow dividing assembly to adjust according to the determined proportion.

The method can be applied to electronic equipment, such as a computer, a processor and the like, and after the electronic equipment is executed, control signals are output to each shunt assembly to control each shunt assembly to adjust the shunt proportion.

For the portions of the technical solution of the control method of the energy storage system and the beneficial effects thereof, which are not described in detail in the present embodiment, reference may be made to the description related to the energy storage system provided in the present embodiment, and details are not repeated here.

Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.

The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather to enable any modification, equivalent replacement, improvement or the like to be made within the spirit and principles of the application.

In the present description and embodiments, if the personal information processing is concerned, the processing is performed on the premise of having a legal basis (for example, obtaining agreement of the personal information body, or being necessary for executing a contract, etc.), and the processing is performed only within a prescribed or agreed range. The user refuses to process the personal information except the necessary information of the basic function, and the basic function is not influenced by the user.

Claims

1. An energy storage system comprising an energy storage circuit in fluid communication with an energy storage fluid and a first heat exchange circuit in fluid communication with a heat exchange fluid;

2. The energy storage system of claim 1, further comprising:

3. The energy storage system of claim 1, wherein the first heat exchange circuit includes a heat collector for collecting thermal energy, and wherein the at least one heat exchanger includes at least one heater for heating the stored energy fluid using thermal energy provided by the heat collector, and wherein a channel of each heater connected in series in the stored energy circuit is disposed in a path into any one of the energy conversion devices.

4. The energy storage system of claim 3, further comprising an underground thermal storage device in the first heat exchange circuit for recovering the thermal energy.

5. The energy storage system of claim 3, wherein the heat collection device comprises a solar heat collection device and/or a geothermal heat collection device.

6. The energy storage system of claim 1, further comprising a second heat exchange circuit including a cold collector for collecting cold energy, wherein the at least one heat exchanger includes at least one cooling device for cooling the stored energy fluid using cold energy provided by the cold collector, and wherein each cooling device is connected in series with a passage in the stored energy circuit and is disposed in a path from any one of the energy conversion devices.

7. The energy storage system of claim 1, wherein the tank circuit further comprises:

8. The energy storage system of claim 1, wherein the renewable energy source is wind-solar electrical energy, the energy storage system further comprising:

9. The energy storage system of claim 1, characterized in that the energy storage system further comprises:

10. A method of controlling an energy storage system, characterized in that the method is applied to an energy storage system according to any one of claims 1-9, the method comprising: