CN119813309A

CN119813309A - Energy storage system, control method of energy storage system and storage medium

Info

Publication number: CN119813309A
Application number: CN202411930446.4A
Authority: CN
Inventors: 侯子安; 刘建波; 易昊昊
Original assignee: Eve Energy Storage Co Ltd
Current assignee: Eve Energy Storage Co Ltd
Priority date: 2024-12-25
Filing date: 2024-12-25
Publication date: 2025-04-11

Abstract

The application provides an energy storage system, a control method of the energy storage system and a storage medium, wherein the energy storage system is connected with a power grid and comprises a battery module, the voltage range of the battery module is between a first voltage and a second voltage, the second voltage is larger than the first voltage, a first end of the energy storage converter is connected with the battery module, a second end of the energy storage converter is connected with the power grid, the initial voltage range of the energy storage converter is between an initial lower limit voltage and an initial upper limit voltage, the initial lower limit voltage is larger than the first voltage or the initial upper limit voltage is smaller than the second voltage, and the energy storage system is used for adjusting the voltage range of the energy storage converter from the initial voltage range to a target voltage range so that the target voltage range is matched with the voltage range of the battery module, wherein the target voltage range is between the target lower limit voltage and the target upper limit voltage, the target lower limit voltage is smaller than or equal to the first voltage, and the target upper limit voltage is larger than or equal to the second voltage. The application can enable the target voltage range after the energy storage converter is adjusted to cover the voltage range of the battery module, thereby improving the energy utilization rate of the energy storage system.

Description

Energy storage system, control method of energy storage system and storage medium

Technical Field

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

Background

An energy storage system refers to a system that is capable of storing electrical energy and releasing the electrical energy when needed. The energy storage system plays a vital role in the power system, and can improve the energy efficiency, balance the supply and demand, provide a standby power supply, support the integration of renewable energy sources and enhance the stability and reliability of a power grid. The energy storage converter is an important component of the energy storage system and is a bridge for connecting the energy storage system and the power grid.

Electrochemical energy storage is applied to a battery module of an energy storage system as an important resource in the construction of a novel power system, but the voltage range of the battery module is not matched with that of an energy storage converter due to the wider voltage range of the battery module. In the related art, the battery module is matched with the voltage range of the energy storage converter by increasing the discharge cut-off voltage of the battery module or reducing the discharge cut-off voltage of the battery module, but the electric quantity of part of the battery module is sacrificed in the mode, so that the energy utilization rate of the energy storage system is reduced.

Disclosure of Invention

The application provides an energy storage system, a control method of the energy storage system and a storage medium, which improve the energy utilization rate of the energy storage system.

In a first aspect, the present application provides an energy storage system, the energy storage system being connected to a power grid, the energy storage system comprising:

A battery module having a voltage range between a first voltage and a second voltage, the second voltage being greater than the first voltage;

The first end of the energy storage converter is connected with the battery module, the second end of the energy storage converter is connected with the power grid, and the initial voltage range of the energy storage converter is between an initial lower limit voltage and an initial upper limit voltage, wherein the initial lower limit voltage is larger than the first voltage or the initial upper limit voltage is smaller than the second voltage;

The energy storage system is used for adjusting the voltage range of the energy storage converter from the initial voltage range to a target voltage range so as to enable the target voltage range to be matched with the voltage range of the battery module, wherein the target voltage range is between a target lower limit voltage and a target upper limit voltage, the target lower limit voltage is smaller than or equal to the first voltage, and the target upper limit voltage is larger than or equal to the second voltage.

In some embodiments of the application, the energy storage system further comprises an isolation transformer disposed between the energy storage converter and the power grid, a first end of the isolation transformer being connected to a second end of the energy storage converter, the second end of the isolation transformer being connected to the power grid.

In some embodiments of the present application, the second end of the energy storage converter is a three-phase three-wire system, and the second end of the isolation transformer is a three-phase four-wire system;

The isolation transformer is used for converting a three-phase three-wire system at the second end of the energy storage converter into a three-phase four-wire system at the second end of the isolation transformer.

In some embodiments of the application, the energy storage system further comprises a load connected to the second end of the isolation transformer for transmitting the output voltage of the battery module to the load.

In some embodiments of the application, the three-phase four-wire system of the second end of the isolation transformer comprises a neutral wire and three phase wires, and the load is connected to the neutral wire and one of the phase wires of the second end of the isolation transformer.

In some embodiments of the application, the energy storage system further comprises a control module for adjusting the voltage range of the energy storage converter from the initial voltage range to the target voltage range based on a parameter adjustment strategy and/or a mode adjustment strategy.

In some embodiments of the application, the battery module is a sodium ion battery module comprising a plurality of sodium ion battery cells, each of the sodium ion battery cells having a voltage ranging between 1.5V and 3.95V.

In some embodiments of the application, the isolation transformer is a Dyn11 type isolation transformer.

In a second aspect, the application provides a control method of an energy storage system, the energy storage system is connected with a power grid, the energy storage system comprises a battery module and an energy storage converter, the voltage range of the battery module is between a first voltage and a second voltage, the second voltage is larger than the first voltage, a first end of the energy storage converter is connected with the battery module, and a second end of the energy storage converter is connected with the power grid, the method comprises the following steps:

Responding to an adjustment instruction, acquiring an initial voltage range of the energy storage converter, wherein the initial voltage range of the energy storage converter is between an initial lower limit voltage and an initial upper limit voltage, and the initial lower limit voltage is larger than the first voltage or the initial upper limit voltage is smaller than the second voltage;

And adjusting the voltage range of the energy storage converter from the initial voltage range to a target voltage range based on a preset adjustment strategy so as to enable the target voltage range to be matched with the voltage range of the battery module, wherein the target voltage range is between a target lower limit voltage and a target upper limit voltage, the target lower limit voltage is smaller than or equal to the first voltage, and the target upper limit voltage is larger than or equal to the second voltage.

In some embodiments of the present application, the adjusting the voltage range of the energy storage converter from the initial voltage range to a target voltage range based on a preset adjustment strategy to match the target voltage range to the voltage range of the battery module includes:

And adjusting the voltage range of the energy storage converter from the initial voltage range to the target voltage range based on a parameter adjustment strategy and/or a mode adjustment strategy.

In a third aspect, the present application provides a computer readable storage medium storing computer program code for implementing the steps of a method of controlling an energy storage system as described above, when the computer program is run on a computer.

The application provides an energy storage system, a control method of the energy storage system and a storage medium, wherein the energy storage system is connected with a power grid and comprises a battery module and an energy storage converter, the voltage range of the battery module is between a first voltage and a second voltage, the second voltage is larger than the first voltage, a first end of the energy storage converter is connected with the battery module, a second end of the energy storage converter is connected with the power grid, the initial voltage range of the energy storage converter is between an initial lower limit voltage and an initial upper limit voltage, the initial lower limit voltage is larger than the first voltage or the initial upper limit voltage is smaller than the second voltage, the energy storage system is used for adjusting the voltage range of the energy storage converter from the initial voltage range to the target voltage range, so that the target lower limit voltage in the target voltage range of the energy storage converter is smaller than or equal to the first voltage, and the target upper limit voltage is larger than or equal to the second voltage, the adjusted target voltage range of the energy storage converter can cover the voltage range of the battery module, and the energy utilization rate of the energy storage system is improved.

Drawings

In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are necessary for the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application and that other drawings may be obtained from them without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a first configuration of an energy storage system according to an embodiment of the present application;

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

FIG. 3 is a schematic diagram of a third configuration of an energy storage system according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a fourth configuration of an energy storage system according to an embodiment of the present application;

Fig. 5 is a flowchart of a control method of an energy storage system according to an embodiment of the present application.

Detailed Description

In order to make the features and advantages of the present application more comprehensible, embodiments accompanied with figures in the present application are described in detail below, wherein the embodiments are described only in some but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

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 certain aspects of the application as detailed in the accompanying claims.

The terms "first," "second," and the like, are used below for descriptive purposes only and are not to be construed as implying or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.

The energy storage converter and the battery module are important components of the energy storage system, but the voltage range of the battery module is wider, so that the voltage range of the battery module cannot be matched with the voltage range of the energy storage converter. In the related art, the battery module is matched with the voltage range of the energy storage converter by increasing the discharge cut-off voltage of the battery module or reducing the discharge cut-off voltage of the battery module, but the electric quantity of part of the battery module is sacrificed in the mode, so that the energy utilization rate of the energy storage system is reduced.

In order to solve the problems in the related art, the embodiments of the present application provide an energy storage system, and the following detailed descriptions will be provided, wherein the description sequence of the following embodiments is not to be taken as a limitation on the preferred sequence of the embodiments.

It should be noted that the energy storage system may include devices such as a battery module, an energy storage converter, a battery management system, an energy management system, a fire protection system, and a temperature control system. The energy storage system comprises an energy storage system, an energy storage converter, a battery management module, an energy management system, a fire protection system and a temperature control system, wherein the battery module is a core part of the energy storage system and is responsible for actual energy storage and release, the energy storage converter is responsible for converting direct current of the battery module into alternating current to be transmitted to a power grid and a load thereof or rectifying the alternating current of the power grid into direct current to be transmitted to the battery module, the battery management module is used for monitoring and managing states of voltage, current, temperature, battery residual capacity and the like of the battery module to ensure safe, reliable and efficient operation of the battery module, the energy management system is responsible for energy scheduling and optimal management of the whole energy storage system, a reasonable charge and discharge strategy is formulated according to factors such as power grid requirements, electricity price signals and renewable energy power generation conditions so as to improve economical efficiency and efficiency of the energy storage system, the fire protection system is used for guaranteeing safety of the energy storage system, fire safety accidents are prevented, and the temperature control system is used for adjusting working temperature of energy storage equipment, keeping the working within a proper temperature range, improving system performance and prolonging service life of the equipment.

Referring to fig. 1, fig. 1 is a schematic diagram of a first structure of an energy storage system according to an embodiment of the application. The energy storage system 10 provided in this embodiment is connected to the power grid 20, such as the energy storage system 10 is electrically connected to the power grid 20, so as to achieve power transmission between the energy storage system 10 and the power grid 20. The energy storage system 10 may be an outdoor energy storage device such as an energy storage outdoor cabinet that can be adapted for use in industrial and commercial settings, micro-grids, backup power sources, and the like.

In some embodiments, the energy storage system 10 may include a battery module 11 and an energy storage converter 12, and the voltage of the battery module 11 may range between a first voltage and a second voltage, the second voltage being greater than the first voltage. The battery module 11 may be an electrochemical battery module such as a sodium ion battery module, a lithium ion battery module, or the like, and if the battery module 11 is a sodium ion battery module, the battery module 11 may include a plurality of sodium ion battery cells, and a voltage range of each sodium ion battery cell is between 1.5V and 3.95V.

The battery module 11 is formed by connecting a plurality of sodium ion battery cells in series to meet the required voltage and capacity, and the voltage range of the battery module 11 is positively related to the number of the sodium ion battery cells connected in series. For example, if the battery module 11 includes 100 sodium ion battery cells connected in series, the voltage of the battery module 11 ranges between 150V and 395V, i.e., the first voltage is 150V and the second voltage is 395V, and if the battery module 11 includes 400 sodium ion battery cells connected in series, the voltage of the battery module 11 ranges between 600V and 1580V, i.e., the first voltage is 600V and the second voltage is 1580V. The series connection of the plurality of sodium ion battery cells in the battery module 11 is not particularly limited, and may be set according to the actual situation, for example, a 1-to-16 series connection method, a 1-to-8 series connection method, and the like.

Accordingly, if the battery module 11 is a lithium ion battery module, the battery module 11 may include a plurality of lithium ion battery cells, and a voltage range of each lithium ion battery cell is between 3.0V and 4.2V. The voltage range of the sodium ion battery monomer is wider than that of the lithium ion battery monomer due to potential change caused by electrochemical reaction between the electrode material and the electrolyte in the charge and discharge processes of the sodium ion battery monomer.

It should be noted that, the energy storage converter is used as a bridge connecting the battery module and the power grid, and can rectify the alternating current of the power grid into direct current and transmit the direct current of the battery module to the battery module, and also can invert the direct current of the battery module into alternating current and transmit the alternating current to the power grid and the load thereof, so that in order to enable the battery module and the energy storage converter to work normally, the voltage range of the energy storage ac needs to be matched with the voltage range of the battery module, that is, the voltage range of the battery module should be within the voltage range acceptable by the energy storage converter, so as to ensure the sufficiency and conversion efficiency of the electric energy conversion between the battery module and the power grid, and also ensure the safety and stability of the battery module in the charging and discharging process, and avoid damage to the battery module caused by overhigh or overlow voltage.

The voltage range of the energy storage converter is usually between 600V and 1000V, or between 1000V and 1500V. If the battery module is a lithium ion battery module, the voltage range of the lithium ion battery cells is between 3.0V and 4.2V, if the battery module comprises 200 lithium ion battery cells which are connected in series, the voltage range of the battery module is between 600V and 840V, the energy storage converter with the voltage range between 600V and 1000V can cover the voltage range of the battery module, and if the battery module comprises 350 lithium ion battery cells which are connected in series, the voltage range of the battery module is between 1050V and 1470V, and the energy storage converter with the voltage range between 1000V and 1500V can cover the voltage range of the battery module. It can be understood that if the battery module is a lithium ion battery module, the voltage range of the lithium ion battery cell is narrower, so that the voltage range of the energy storage converter can cover the voltage range of the battery module, and under the condition that the battery module is fully discharged and the voltage range of the energy storage converter is not adjusted, the voltage range of the energy storage converter can still be ensured to cover the voltage range of the lithium ion battery module, so that the energy storage converter is matched with the lithium ion battery module.

Correspondingly, if the battery module is a sodium ion battery module, the voltage range of the sodium ion battery monomer is between 1.5V and 3.95V, if the battery module comprises 400 lithium ion battery monomers which are mutually connected in series, the voltage range of the battery module is between 600V and 1580V, and at the moment, the voltage range of the battery module cannot be covered by the energy storage converter which is between 600V and 1000V or between 1000V and 1500V, so that the battery module and the energy storage converter cannot work normally. In order to solve the problem of the voltage range of the battery module and the energy storage converter being not adaptive due to the fact that the voltage range of the sodium ion battery monomer is wider, the voltage range of the sodium ion battery module and the voltage range of the energy storage converter are adjusted under the condition that the sodium ion battery module can be fully charged and discharged, the battery module and the energy storage converter are enabled to be adaptive, normal operation of the battery module and the energy storage converter is guaranteed, and therefore the energy utilization rate of an energy storage system is improved.

Specifically, the energy storage system 10 includes an energy storage converter 12, a first end of the energy storage converter 12 is connected to the battery module 11, such as electrically connected, and a second end of the energy storage converter 12 is connected to the power grid 20, such as electrically connected, where an initial voltage range of the energy storage converter 12 is between an initial lower limit voltage and an initial upper limit voltage, and the initial lower limit voltage is greater than the first voltage or the initial upper limit voltage is less than the second voltage.

The energy storage converter 12 is disposed between the battery module 11 and the power grid 20, and a first end of the energy storage converter 12 is a side close to the battery module 11 and far away from the power grid 20, and since the energy storage converter 12 can rectify the alternating current of the power grid 20 into direct current and transmit the direct current to the battery module 11, the first end of the energy storage converter 12 can be an alternating current output end on the alternating current side, and the energy storage converter can also invert the direct current of the battery module into alternating current and transmit the alternating current to the power grid and a load thereof, and therefore the first end of the energy storage converter 12 can be a direct current input end on the direct current side. Correspondingly, the second end of the energy storage converter 12 is a side close to the power grid 20 and far from the battery module 11, and the second end of the energy storage converter 12 may be an ac input end on the ac side and may be a dc output end on the dc side.

The initial voltage range of the energy storage converter 12 is a voltage range before unregulated, for example, the initial voltage range may be between 600V and 1000V or between 1000V and 1500V, and the initial voltage range may be adapted to the lithium ion battery module, but the voltage range of the sodium ion battery module is wider, so the initial voltage range is not adapted to the voltage range of the lithium ion battery module. The battery module 11 in this embodiment is a sodium ion battery module, the voltage range of the battery module 11 is between the first voltage and the second voltage, and since the initial voltage range is not adapted to the voltage range of the lithium ion battery module, the initial lower limit voltage of the initial voltage range is greater than the first voltage of the battery module 11 or the initial upper limit voltage is smaller than the second voltage of the battery module 11, for example, the voltage range of the battery module 11 is between 600V and 1580V, the initial lower limit voltage may be 1000V, which is greater than the first voltage 600V of the battery module 11, or the initial upper limit voltage may be 1500V, which is smaller than the second voltage 1580V of the battery module 11.

It will be appreciated that, in order to enable the voltage range of the energy storage converter 12 to cover the voltage range of the battery module 11, the present embodiment adjusts the voltage range of the energy storage converter 12, and adjusts the voltage range of the energy storage converter 12 from the initial voltage range to the target voltage range so that the target voltage range matches the voltage range of the battery module 11. The target voltage range is between a target lower limit voltage and a target upper limit voltage, the target lower limit voltage is smaller than or equal to the first voltage, and the target upper limit voltage is larger than or equal to the second voltage. For example, the lower limit voltage of the energy storage converter 12 is adjusted from the initial lower limit voltage 1000V to the target lower limit voltage 600V, the target lower limit voltage is equal to the first voltage 600V of the battery module 11, the upper limit voltage of the energy storage converter 12 is adjusted from the initial upper limit voltage 1500V to the target upper limit voltage 1600V, and the target upper limit voltage is greater than the second voltage 1580V of the battery module 11, so that the target voltage range, that is, 600V-1500V, can cover the voltage range 600V-1580V of the battery module 11, the voltage range of the battery module 11 is matched with the target voltage range of the energy storage converter 12, and the battery module 11 can ensure that the battery module 11 and the energy storage converter 12 work normally under the condition of full discharging, thereby improving the energy utilization rate of the energy storage system 10.

In some embodiments, the voltage range of the sodium ion battery cell during operation may be generally less than 1.5V-3.95V, for example, the voltage range of the sodium ion battery cell may be 1.5V-3.75V, and if the battery module 11 is composed of 400 sodium ion battery cells connected in series, the voltage range of the battery module 11 is 600V-1500V, i.e., the first voltage is 600V and the second voltage is 1500V. At this time, since the initial upper limit voltage 1500V of the energy storage converter 12 is equal to the second voltage 1500V and the initial lower limit voltage 1000V is greater than the first voltage 600V, when the voltage range of the energy storage converter 12 is adjusted, only the lower limit voltage is needed to be adjusted without adjusting the upper limit voltage, i.e. the initial lower limit voltage 1000V is adjusted to the target lower limit voltage 600V and the initial upper limit voltage 1500V is equal to the target upper limit voltage 1500V, so that the adjustment efficiency of the energy storage converter 12 can be improved. Of course, only the initial upper limit voltage may be adjusted without adjusting the initial lower limit voltage, and the specific adjustment strategy needs to be set according to the initial voltage range and the voltage range of the battery module 12, which is not limited herein. And the voltage range of the battery module 12 is related to the number of sodium-ion cells according to the voltage range of the sodium-ion cells inside thereof.

In some embodiments, the energy storage system 20 may further include a control module that may be electrically connected to the energy storage converter 12, or that may be disposed within the energy storage converter 12, and that may be configured to adjust the voltage range of the energy storage converter 12 from an initial voltage range to a target voltage range based on a parameter adjustment strategy and/or a mode adjustment strategy.

Optionally, describing with a parameter adjustment strategy, if the voltage range of the battery module 11 is 600V-1580V and the initial voltage range of the energy storage converter 12 is 1000V-1500V, the internal control algorithm of the energy storage converter 12 is adjusted to change the voltage control strategy of the energy storage converter 12, so that the voltage control strategy can adapt to the input voltage lower than 1000V or higher than 1500V, and the energy storage converter 12 can still work normally and output stable current when detecting that the input voltage is lower than 1000V or higher than 1500V. For example, the minimum operating voltage value and the maximum operating voltage value set inside the energy storage converter 12 are reduced, that is, the voltage range of the energy storage converter 12 is adjusted to the target voltage range, so that the energy storage converter 12 can accept the input voltage of the battery module 11, and meanwhile, the set values of other relevant parameters, such as current or power, of the energy storage converter 12 are adjusted to be matched with the target voltage range, so as to ensure the normal operation and safety of the energy storage converter 12.

Alternatively, the mode adjustment strategy is described, and if the voltage range of the battery module 11 is 600V-1580V, the initial voltage range of the energy storage converter 12 is 1000V-1500V. If the input voltage of the battery module 11 is within the initial voltage range, the output power of the energy storage converter 12 is rated power, and the operation mode of the energy storage converter 12 is normal operation mode, and if the input voltage of the battery module 11 is not within the initial voltage range, the operation mode of the energy storage converter 12 is adjusted to derate operation mode or boost operation mode by reducing or increasing the output power of the energy storage converter 12. Specifically, the working mode of the energy storage converter 12 is dynamically adjusted by acquiring the input voltage of the energy storage converter 12 in real time, so that the target voltage range covers the voltage range of the battery module 11 to ensure that the energy storage converter 12 and the battery module 11 work normally, and in the process of monitoring the energy storage converter 12 in real time, faults such as abnormal voltage, overload and overheat can be timely detected by the energy storage converter 12 in the derating working mode or the increasing working mode, and corresponding protection measures can be timely taken, such as reducing output power, starting a cooling system and the like, so that safe operation of the energy storage converter 12 is ensured.

As can be seen from the above, the energy storage system 10 provided in this embodiment includes the battery module 11 and the energy storage converter 12, wherein the voltage range of the battery module 11 is between the first voltage and the second voltage, the second voltage is greater than the first voltage, the first end of the energy storage converter 12 is connected to the battery module 11, the second end of the energy storage converter 12 is connected to the power grid 20, the initial voltage range of the energy storage converter 12 is between the initial lower limit voltage and the initial upper limit voltage, the initial lower limit voltage is greater than the first voltage or the initial upper limit voltage is less than the second voltage, the energy storage system 10 is configured to adjust the voltage range of the energy storage converter 12 from the initial voltage range to the target voltage range, so that the target lower limit voltage in the target voltage range of the energy storage converter 12 is less than or equal to the first voltage, and the target upper limit voltage is greater than or equal to the second voltage, thereby enabling the adjusted target voltage range of the energy storage converter 12 to cover the voltage range of the battery module 11 without sacrificing the battery module for matching with the voltage range of the energy storage converter, and improving the energy utilization rate of the energy storage system.

It should be noted that, the second end, i.e., the dc output end or the ac input end, of the energy storage converter 12 of the energy storage system 10 is a three-phase three-wire system, the three-phase three-wire system circuit includes three phase wires, no neutral wire, only can provide line voltage but cannot provide phase voltage, and the circuit is suitable for three-phase symmetrical loads but not suitable for single-phase loads, and the application scenario of the energy storage system such as the energy storage outdoor cabinet is mostly the scenario of industrial and commercial storage, optical storage and charging, and the load types are diversified in the application scenario of industrial and commercial storage, optical storage and charging, and the like, and the circuit has three-phase symmetrical loads such as large mechanical equipment, air conditioning systems and the like, and also has single-phase loads such as lighting, sockets and the like, and the three-phase three-wire system cannot provide phase voltage such as 220V required by the single-phase loads but cannot meet the power consumption requirement of the single-phase loads.

In addition, if the three-phase three-wire system at the second end of the energy storage converter 12 is directly connected to the power grid, there is an electrical connection between the grounding system of the power grid and the battery module 11, and the grounding system of the power grid will interfere with the insulation detection of the battery module 11 to cause abnormal current in the detection loop, so that the insulation detection function of the battery module 11 will fail; when the energy storage system operates, the insulation resistance is very low, if a direct-current ground short circuit occurs, the short circuit current flows back to the battery module by using the grounding system of the power grid to form a short circuit loop, the damage is large, the normal operation of the battery module or the energy storage system is influenced by the harmonic wave of the power grid or the load, the sampling of the battery management system of the energy storage system is influenced when the harmonic wave is serious, the battery management system cannot accurately judge the state of the battery module, namely, the direct three-phase three-wire system access power grid at the second end of the energy storage converter 12 is unsuitable for the energy storage system such as an energy storage outdoor cabinet.

In order to solve the above problems caused by direct connection of the three-phase three-wire energy storage converter to the power grid, in this embodiment, an isolation transformer is added between the energy storage converter and the power grid, so that the connection side of the energy storage system and the power grid is a three-phase four-wire system. Specifically, referring to fig. 2, fig. 2 is a schematic diagram of a second structure of an energy storage system according to an embodiment of the application. The energy storage system 10 may further comprise an isolation transformer 13, the isolation transformer 13 being arranged between the energy storage converter 12 and the power grid 20, in particular a first end of the isolation transformer 13 being connected, such as electrically connected, to a second end of the energy storage converter 12, and a second end of the isolation transformer 13 being connected, such as electrically connected, to the power grid 20.

The second end of the energy storage converter 12 is a three-phase three-wire system, that is, the second end of the energy storage converter 12 includes three phase lines, and the second end of the isolation transformer 13 is a three-phase four-wire system, that is, the second end of the isolation transformer 13 includes one neutral line and three phase lines. The isolation transformer 13 is configured to convert a three-phase three-wire system at the second end of the energy storage converter 12 into a three-phase four-wire system at the second end of the isolation transformer 13.

Alternatively, the isolation transformer 13 may be a Dyn11 type isolation transformer, where Dyn11 represents a connection mode and a phase relationship of windings of the isolation transformer, D represents a delta connection mode of the high-voltage windings, the delta connection windings can provide better lightning impulse resistance, and no zero sequence current is generated when a single-phase grounding fault occurs, so that the protection of the energy storage system 10 is facilitated, y represents the low-voltage windings in a star connection mode, the star connection windings can provide a neutral point, so that a neutral line of the isolation transformer is conveniently led out, and the isolation transformer is suitable for an occasion where a phase voltage needs to be provided, n represents the neutral point of the low-voltage windings, and this grounding mode helps to stabilize the voltage of the low-voltage side, so as to improve the safety and reliability of the energy storage system 10, and 11 represents the phase relationship between the high-voltage windings and the low-voltage windings, i.e. the voltage phasor of the low-voltage windings lags by 330 ° or 30 ° relative to the voltage phasor of the high-voltage windings, which helps to reduce the influence of the harmonic.

It should be noted that, the three-phase four-wire system can provide line voltage and phase voltage simultaneously, can satisfy the power consumption demand of three-phase load and single-phase load, be applicable to symmetrical and asymmetrical load, through the introduction of neutral line, can effectively reduce voltage fluctuation and electric energy quality problem, improve the stability of system and the operational reliability of energy storage system, and the neutral line can provide current loop balancing three-phase load, improve the security and the reliability of energy storage system, because the application scenario of energy storage system 10 such as the outdoor cabinet of energy storage is mostly industrial and commercial storage, light stores up and fills etc. the scene, the load includes three-phase load and single-phase load, therefore, through setting up the energy storage system 10 and power grid 20 connection one side into three-phase four-wire system, namely through the three-phase four-wire system of the second end of isolation transformer 13 with energy storage converter 12 converts the three-phase three-wire system of the second end into the three-phase four-wire system of the second end of isolation transformer 13, can satisfy the power consumption demand of three-phase load and single-phase load under the scene such as industrial and commercial storage, light stores up.

In some embodiments, since the isolation transformer 13 is disposed between the battery module 11 and the power grid 20, if the battery module is shorted to the ground by the positive/negative pole, the isolation transformer 13 can block the circuit, so that the short circuit generated by the energy storage system 10 will not affect the power grid 20, and correspondingly, the short circuit generated by the power grid 20 will also be blocked by the isolation transformer 13 without affecting the energy storage system 10. In addition, since the input end and the output end of the isolation transformer 13 are completely isolated, the voltage of the input end does not influence the output end, so that the risk of electric shock is reduced, the energy storage system 10 is safer, and the isolation transformer 13 can effectively prevent personal injury caused by accidents such as electric leakage and electric shock.

In some embodiments, the isolation transformer 13 can isolate the harmonic wave generated by the power grid or the load, so as to avoid the electromagnetic interference of the energy storage system 10, reduce the influence of the electromagnetic compatibility problem on the energy storage system, enable the battery module or the energy storage system to work normally, further improve the sampling accuracy of the battery management module, and improve the state judgment accuracy of the battery module.

Referring to fig. 3, fig. 3 is a schematic diagram of a third structure of an energy storage system according to an embodiment of the application. The energy storage system 10 may further include a load 14, where the load 14 is connected to a second terminal of the isolation transformer 13, and the isolation transformer 13 is configured to transmit the output voltage of the battery module 11 to the load 14. The three-phase four-wire system of the second end of the isolation transformer 13 includes one neutral line and three phase lines, and the load 14 is connected to the neutral line and one of the phase lines of the second end of the isolation transformer 13 so that the output voltage of the battery module 11 can be transmitted to the load 14 after passing through the isolation transformer 13.

It should be noted that, the isolation transformer 13 not only can convert the three-phase three-wire system at the second end of the energy storage converter 12 into the three-phase four-wire system at the second end of the isolation transformer 13 so that the energy storage system 10 can be connected with the power grid, the three-phase four-wire system at the second end of the isolation transformer 13 is provided with a neutral wire, so that the second end of the isolation transformer 13 can be connected with the load 14, the isolation transformer 13 is used for transmitting the output voltage of the battery module 11 to the load 14, so that the load 14 can not only receive the electric energy of the power grid 20, but also receive the electric energy of the battery module 11, and if the power grid 20 fails, the electric energy can not supply the electric energy to the load 14 through the discharging of the battery module 11 of the energy storage system 10, so as to ensure the normal operation of the load 14, and the safety and the economical efficiency of the energy storage system 10 are improved.

In some embodiments, referring to fig. 4, fig. 4 is a schematic diagram of a fourth structure of an energy storage system according to an embodiment of the present application. The load 14 may include an uninterruptible power supply 141 (Uninterruptible Power Supply, UPS) and a liquid cooling machine 142, where the UPS is a device capable of providing continuous and stable power supply, and the UPS not only can play a role in stabilizing voltage when the voltage of the energy storage system 10 is unstable, but also can provide uninterrupted power guarantee for important loads such as a battery management system and a fire protection system in the energy storage system 10 when the mains supply is interrupted, and the liquid cooling machine 142 can ensure that the battery core of the battery module 11 works in a suitable temperature range, so as to improve the service life of the battery module 11 and the working efficiency of the energy storage system 10.

In addition, the energy storage system 10 may further include a high voltage tank 15, where the high voltage tank 15 is disposed between the battery module 11 and the energy storage converter 12, and specifically, a first end of the high voltage tank 15 is connected to a second end of the battery module 11, and a second end of the high voltage tank 15 is connected to a first end of the energy storage converter 12. The high-voltage tank 15 can realize functions of charge and discharge control, protection, monitoring and the like of the energy storage system 10, and the high-voltage tank 15 can effectively prevent electric faults and safety accidents of the energy storage system 10 in the operation process through the control and protection functions, so that the safety and reliability of the energy storage system 10 are ensured.

In order to further describe the energy storage system, the embodiment of the present application further provides a control method of the energy storage system, please refer to fig. 5, fig. 5 is a flow chart of the control method of the energy storage system provided by the embodiment of the present application. The control method of the energy storage system comprises the following specific procedures that the first end of the energy storage converter is connected with the battery module, the second end of the energy storage converter is connected with the power grid, and the control method of the energy storage system comprises the following steps:

101. And responding to the adjustment instruction, acquiring an initial voltage range of the energy storage converter, wherein the initial voltage range of the energy storage converter is between an initial lower limit voltage and an initial upper limit voltage, and the initial lower limit voltage is larger than the first voltage or the initial upper limit voltage is smaller than the second voltage.

The voltage range of the energy storage converter is typically between 600V and 1000V, or between 1000V and 1500V. If the battery module is a sodium ion battery module, the voltage range of the sodium ion battery monomer is between 1.5V and 3.95V, if the battery module comprises 400 lithium ion battery monomers which are mutually connected in series, the voltage range of the battery module is between 600V and 1580V, and at the moment, the voltage range of the battery module cannot be covered by the energy storage converter which is between 600V and 1000V or between 1000V and 1500V, so that the battery module and the energy storage converter cannot work normally. In order to solve the problem of the voltage range of the battery module and the energy storage converter being not adaptive due to the fact that the voltage range of the sodium ion battery monomer is wider, the voltage range of the sodium ion battery module and the voltage range of the energy storage converter are adjusted under the condition that the sodium ion battery module can be fully charged and discharged, the battery module and the energy storage converter are enabled to be adaptive, normal operation of the battery module and the energy storage converter is guaranteed, and therefore the energy utilization rate of an energy storage system is improved.

The initial voltage range of the energy storage converter 12 is a voltage range before being unregulated, for example, the initial voltage range may be between 600V and 1000V or between 1000V and 1500V, and the voltage range of the sodium ion battery module is not adapted to the voltage range of the lithium ion battery module because the voltage range of the sodium ion battery module is wider, so that the voltage range of the energy storage converter needs to be regulated. Specifically, in response to the adjustment command, an initial voltage range of the energy storage converter is obtained, the voltage range of the battery module 11 is between the first voltage and the second voltage, and because the initial voltage range is not adapted to the voltage range of the lithium ion battery module, an initial lower limit voltage of the initial voltage range is greater than the first voltage of the battery module 11 or an initial upper limit voltage is smaller than the second voltage of the battery module 11, for example, the voltage range of the battery module 11 is between 600V and 1580V, the initial lower limit voltage may be 1000V, the initial lower limit voltage 1000V is greater than the first voltage 600V of the battery module 11, or the initial upper limit voltage may be 1500V, and the initial upper limit voltage 1500V is smaller than the second voltage 1580V of the battery module 11.

102. And adjusting the voltage range of the energy storage converter from the initial voltage range to a target voltage range based on a preset adjustment strategy so as to enable the target voltage range to be matched with the voltage range of the battery module, wherein the target voltage range is between a target lower limit voltage and a target upper limit voltage, the target lower limit voltage is smaller than or equal to the first voltage, and the target upper limit voltage is larger than or equal to the second voltage.

In some embodiments, the voltage range of the energy storage converter is adjusted from an initial voltage range to a target voltage range based on a parameter adjustment strategy and/or a mode adjustment strategy.

As can be seen from the above, in the embodiment of the present application, the initial voltage range of the energy storage converter is obtained by responding to the adjustment command, and the voltage range of the energy storage converter is adjusted from the initial voltage range to the target voltage range based on the preset adjustment strategy, so that the target voltage range is matched with the voltage range of the battery module. According to the embodiment, the voltage range of the energy storage converter is adjusted to the target voltage range, so that the target lower limit voltage of the energy storage converter is smaller than or equal to the first voltage of the battery module, and the target upper limit voltage of the energy storage converter is larger than or equal to the second voltage of the battery module, and therefore the adjusted target voltage range of the energy storage converter covers the voltage range of the battery module, and the energy utilization rate of the energy storage system is improved.

Those of ordinary skill in the art will appreciate that all or a portion of the steps of the various methods of the above embodiments may be performed by instructions, or by instructions controlling associated hardware, which may be stored in a computer-readable storage medium and loaded and executed by a processor.

To this end, an embodiment of the present application provides a computer readable storage medium, in which a computer program code is stored, which when run on a computer causes the computer to execute the above-mentioned related method steps to implement the steps of the method for controlling an energy storage system provided in the above-mentioned embodiment. For example, the following steps may be specifically performed:

Responding to the adjustment instruction, acquiring an initial voltage range of the energy storage converter, wherein the initial voltage range of the energy storage converter is between an initial lower limit voltage and an initial upper limit voltage, and the initial lower limit voltage is larger than the first voltage or the initial upper limit voltage is smaller than the second voltage;

The specific implementation of each operation above may be referred to the previous embodiments, and will not be described herein.

The storage medium may include a Read Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, an optical disk, or the like.

The steps in the control method of any energy storage system provided by the embodiment of the present application can be executed due to the computer program code stored in the storage medium, so that the beneficial effects that can be achieved by the control method of any energy storage system provided by the embodiment of the present application can be achieved, and detailed descriptions of the foregoing embodiments are omitted herein.

The foregoing describes the energy storage system, the control method of the energy storage system and the storage medium in detail, and specific examples are applied to illustrate the principles and embodiments of the present application, and the description of the foregoing examples is only for aiding in understanding of the method and core concept of the present application, and meanwhile, for those skilled in the art, according to the concept of the present application, there are variations in the specific embodiments and application ranges, so that the disclosure should not be construed as limiting the application.

Claims

1. An energy storage system, wherein the energy storage system is connected to a power grid, the energy storage system comprising:

2. The energy storage system of claim 1, further comprising an isolation transformer disposed between the energy storage converter and the power grid, a first end of the isolation transformer connected to a second end of the energy storage converter, and a second end of the isolation transformer connected to the power grid.

3. The energy storage system of claim 2, wherein the second end of the energy storage converter is a three-phase three-wire system and the second end of the isolation transformer is a three-phase four-wire system;

4. The energy storage system of claim 3, further comprising a load connected to the second end of the isolation transformer, the isolation transformer configured to transmit the output voltage of the battery module to the load.

5. The energy storage system of claim 4, wherein said three-phase four-wire system at said second end of said isolation transformer includes a neutral wire and three phase wires, said load being connected to said neutral wire and one of said phase wires at said second end of said isolation transformer.

6. The energy storage system of claim 1, further comprising a control module for adjusting a voltage range of the energy storage converter from the initial voltage range to the target voltage range based on a parameter adjustment strategy and/or a mode adjustment strategy.

7. The energy storage system of claim 1, wherein the battery module is a sodium ion battery module comprising a plurality of sodium ion battery cells, each sodium ion battery cell having a voltage range between 1.5V and 3.95V.

8. The energy storage system of any of claims 2 to 5, wherein the isolation transformer is a Dyn11 type isolation transformer.

9. The control method of the energy storage system is characterized in that the energy storage system is connected with a power grid, the energy storage system comprises a battery module and an energy storage converter, the voltage range of the battery module is between a first voltage and a second voltage, the second voltage is larger than the first voltage, a first end of the energy storage converter is connected with the battery module, and a second end of the energy storage converter is connected with the power grid, and the method comprises the following steps:

10. The method of claim 9, wherein adjusting the voltage range of the energy storage converter from the initial voltage range to a target voltage range based on a preset adjustment strategy to match the target voltage range to the voltage range of the battery module comprises:

11. A computer readable storage medium, characterized in that the computer readable storage medium stores a computer program code for implementing the steps of the method for controlling an energy storage system according to claim 9 or 10 when the computer program runs on a computer.