Energy storage cabinet

Abstract

The embodiment of the utility model discloses an energy storage cabinet, which adopts a mode of adding an additional power converter between an energy storage device and an air conditioning system to meet the power supply requirement of the air conditioning system under the conditions of low-voltage ride-through and off-grid black start. Under the conditions of low-voltage ride-through and off-grid black start, electric energy of the energy storage device is converted through the power converter and then supplied to the air conditioning system, and after the voltage of the power grid is normal or start is completed, a conversion circuit in the air conditioning system is adopted to take electricity from the power grid. The working time of the power converter is very short, so that the power converter can adopt a DC-DC circuit which is relatively low in rated power and supports relatively high transient power, and a low-voltage ride-through scene and an off-grid black-start scene are supported at low cost.

Description

Technical Field

[0001] The present application relates to the technical field of storage batteries, and in particular to an energy storage cabinet. Background Art

[0002] A microgrid refers to an independent power grid that is not connected to the national grid in certain scenarios, such as in remote areas or on islands. Microgrids are usually equipped with new energy power generation devices such as wind or solar energy and energy storage devices. Among them, the energy storage device is placed in an energy storage cabinet, and an air-conditioning system for heat dissipation is also provided in the energy storage cabinet. Before the electric energy stored in the energy storage device is converted into alternating current and transmitted to the grid, the air-conditioning system needs to be started to avoid the risk of thermal runaway of the energy storage cabinet. Since the air-conditioning system draws power from the grid side, the air-conditioning system cannot work when the grid is abnormal, such as low voltage crossing, or when the grid is not established, such as off-grid black start, so that the energy storage cabinet does not support low voltage crossing scenarios and off-grid black start scenarios. Utility Model Content

[0003] The present application provides an energy storage cabinet to achieve low-cost support for low-voltage ride-through scenarios and off-grid black start scenarios.

[0004] In the first aspect, an embodiment of the present application provides an energy storage cabinet, including: an energy storage device, an energy storage converter, an air conditioning system and a power converter. Among them, the energy storage device is connected to the power grid through the energy storage converter, the energy storage device is connected to the air conditioning system through the power converter, and the air conditioning system is connected to the power grid. The air conditioning system includes: a first load, a conversion circuit and a first power supply circuit. The first power supply circuit has two power supply input ports, the first input end of the first power supply circuit is connected to the conversion circuit, the second input end of the first power supply circuit is connected to the power converter, and the output end of the first power supply circuit is connected to the first load. The conversion circuit is connected to the power grid, and the conversion circuit is used to convert the alternating current provided by the power grid into a first voltage and provide it to the first power supply circuit when the voltage amplitude of the power grid is greater than the set threshold; the power converter is used to convert the electric energy of the energy storage device into a second voltage and provide it to the first power supply circuit, and the first voltage is higher than the second voltage. In this way, when the power grid is normal, because the first voltage of the first input end of the first power supply circuit is higher than the second voltage of the second input end, the power converter connected to the second input end is in a standby state, and the first power supply circuit draws power from the power grid through the conversion circuit. When an abnormality occurs in the power grid (i.e., low voltage ride-through), the conversion circuit connected to the first input terminal loses power, causing the output of the conversion circuit to drop from the first voltage to a voltage lower than the second voltage. The first power supply circuit draws power from the energy storage device through the power converter, which can ensure that the first power supply circuit provides uninterrupted power to the first load, so that the first load works uninterruptedly under the drive of the first power supply circuit, thereby ensuring that the air-conditioning system continues to cool the energy storage cabinet. During the continuous operation of the first load, the energy storage converter can convert the electric energy of the energy storage device into AC power and output it to the power grid to maintain the connection between the energy storage cabinet and the power grid during the low voltage ride-through. Alternatively, when there is no electricity in the power grid, i.e., when the power grid is off-grid and black-started, the first power supply circuit directly draws power from the energy storage device through the power converter, starts the first load, and starts to cool the energy storage cabinet. After the first load works, the energy storage converter can be started to convert the electric energy of the energy storage device into AC power and output it to the power grid to support the off-grid black-start.

[0005] In the present application, only during low voltage ride-through or off-grid black start, a power converter arranged between the energy storage device and the air-conditioning system is used to provide a second voltage to the first power supply circuit. After the grid voltage is normal or after the startup is completed, the first power supply circuit uses a conversion circuit to draw power from the grid. Since the working time of the power converter is very short, the power converter can use a DC-to-DC circuit with a small rated power and a large transient power support to realize its power conversion function. In addition, the power converter occupies a small volume, and the power converter can be integrated in the driving auxiliary source module of the air-conditioning system, that is, the power converter can be integrated in the same module as the conversion circuit, or the power converter can also be arranged outside the air-conditioning system, for example, integrated in a module for collecting and controlling the energy balance of the energy storage device, and the added power converter will not occupy too much space in the energy storage cabinet.

[0006] In some embodiments of the present application, the conversion circuit may include a rectifier circuit and a DC conversion circuit, the input end of the rectifier circuit is connected to the power grid, the output end of the rectifier circuit is connected to the input end of the DC conversion circuit, and the first output end of the DC conversion circuit is connected to the first input end of the first power supply circuit. The rectifier circuit is used to convert the AC power provided by the power grid into a high-voltage DC output when the power grid is normal, the DC conversion circuit is used to convert the high-voltage DC power provided by the rectifier circuit into a first low-voltage DC output when the power grid is normal, and the power converter is used to convert the high-voltage electric energy stored in the energy storage device into a second low-voltage DC output, and the voltage of the first low-voltage DC is higher than the voltage of the second low-voltage DC. In this way, since the power converter converts the high-voltage electric energy into the second low-voltage DC output, it is beneficial to save the energy consumption of the power converter when it is in a standby state when the power grid is normal.

[0007] In some embodiments of the present application, the air conditioning system may further include: a second load and a second power supply circuit, and the second output end of the DC conversion circuit is connected to the second load through the second power supply circuit. The output of the conversion circuit is divided into two different DC power supply circuits, namely a first power supply circuit and a second power supply circuit, and the first load, i.e., the important load, is powered by the first power supply circuit, and the second load, i.e., the non-important load, is powered by the second power supply circuit. Since the power of the important load is relatively small, generally accounting for less than 10% of the total power of the air conditioning system, the added power converter only needs to meet the requirements of large transient power and small rated power.

[0008] In some embodiments of the present application, the first load, i.e., the important load, includes: an air conditioning controller, a multi-way valve, and a cooling water pump of an energy storage converter, etc.; the second load, i.e., the non-important load, includes: a cooling water pump and a fan of an energy storage device, etc. The first load machine is powered by the first power supply circuit, and the second load, i.e., the non-important load, is powered by the second power supply circuit. The first power supply circuit has a second input terminal connected to the power converter in addition to the second power supply circuit. During off-grid or low-voltage ride-through, the first power supply circuit draws power from the energy storage device through the power converter to support the operation of the important load, so as to provide partial cooling capacity, such as providing cooling capacity for the energy storage converter, and providing heat dissipation guarantee for the energy storage converter, thereby supporting the energy storage converter to establish the connection between the energy storage device and the power grid. Since the second power supply circuit only draws power from the power grid through the conversion circuit, during off-grid or low-voltage ride-through, the power grid voltage is insufficient to support the second power supply circuit to supply power to the non-important load, and the non-important load stops working.

[0009] In some embodiments of the present application, the air conditioning system further includes a compressor, the conversion circuit further includes an inverter circuit, the input end of the inverter circuit is connected to the output end of the rectifier circuit, and the output end of the inverter circuit is connected to the compressor. Specifically, the conversion circuit can also convert the power grid into the AC power required by the compressor. During off-grid or low-voltage ride-through, the grid voltage is insufficient to support the conversion circuit to power the compressor, so the compressor stops working.

[0010] In some other embodiments of the present application, the air-conditioning system may not distinguish between important loads and non-important loads, that is, all loads in the air-conditioning system, that is, the first load, are powered by the first power supply circuit. Specifically, the conversion circuit may include a rectifier circuit, and the first power supply circuit includes a DC conversion circuit; the input end of the rectifier circuit is connected to the power grid, the output end of the rectifier circuit is connected to the input end of the DC conversion circuit, and the output end of the DC conversion circuit is connected to the first load; the output end of the power converter is connected to the input end of the DC conversion circuit. In this way, when the power grid is normal, the conversion circuit can supply power to the first power supply circuit to meet the normal operation of all loads. When off-grid black start or low voltage crossing occurs in the power grid, the power converter is switched to supply power to the first power supply circuit to meet the short-term normal operation of all loads. After waiting for the power grid to be normal, the conversion circuit is switched to supply power to the first power supply circuit.

[0011] In other embodiments of the present application, the first load includes: an air conditioning controller, a multi-way valve, a cooling water pump of the energy storage converter, a cooling water pump and a fan of the energy storage device. During off-grid or low-voltage crossing, the first power supply circuit draws power from the energy storage device through a power converter to support the above loads to work uninterruptedly to provide full cooling capacity, such as providing cooling capacity for the energy storage converter and the energy storage device, and providing heat dissipation protection for the energy storage converter and the energy storage device, thereby supporting the energy storage converter to establish grid connection between the energy storage device and the power grid.

[0012] In other embodiments of the present application, the first load may also include a compressor, and the first power supply circuit may also include an inverter circuit; the input end of the inverter circuit is respectively connected to the output end of the rectifier circuit and the output end of the power converter, and the output end of the inverter circuit is connected to the compressor. That is, when the power grid is normal, the inverter circuit can convert the direct current output by the rectifier circuit into the alternating current required by the compressor, and when off-grid or during low voltage ride-through, the inverter circuit can convert the direct current provided by the power converter into the alternating current required by the compressor, thereby ensuring uninterrupted operation of the compressor.

[0013] In some embodiments of the present application, in order to prevent the second voltage of the first power supply circuit from flowing back from the first input end to the conversion circuit and damaging the circuit when off-grid black start or low voltage ride-through of the power grid occurs, a first anti-reverse connection circuit may be provided between the conversion circuit and the first input end of the first power supply circuit. The first anti-reverse connection circuit may ensure unidirectional flow of current from the conversion circuit to the first input end of the first power supply circuit, that is, may prevent reverse flow of current from the first input end of the first power supply circuit to the conversion circuit.

[0014] In some embodiments of the present application, in order to prevent the first voltage of the first power supply circuit from flowing back from the second input terminal to the power converter and damaging the device when the power grid is normal, a second anti-reverse connection circuit can be provided between the output terminal of the power converter and the second input terminal of the first power supply circuit. The second anti-reverse connection circuit can ensure the unidirectional flow of current from the power converter to the second input terminal of the first power supply circuit, that is, it can prevent the reverse flow of current from the second input terminal of the first power supply circuit to the power converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0016] Figure 1 A schematic diagram of the architecture of a microgrid system;

[0017] Figure 2 This is a schematic diagram of the structure of the energy storage cabinet of the traditional technical solution;

[0018] Figure 3 A schematic diagram of the structure of an energy storage cabinet provided in an embodiment of the present application;

[0019] Figure 4 A schematic diagram of a specific structure of an energy storage cabinet provided in an embodiment of the present application;

[0020] Figure 5 A schematic diagram of an actual signal waveform of a water pump in an energy storage cabinet provided in an embodiment of the present application;

[0021] Figure 6 Another structural schematic diagram of an energy storage cabinet provided in an embodiment of the present application;

[0022] Figure 7 Another specific structural schematic diagram of the energy storage cabinet provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings.

[0024] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be limiting of the present application. As used in the specification and appended claims of the present application, the singular expressions "a", "an", "said", "above", "the" and "this" are intended to also include expressions such as "one or more", unless there is a clear contrary indication in the context.

[0025] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear at different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0026] In addition, the same reference numerals in the figures represent the same or similar structures, and thus their repeated description will be omitted. The words expressing positions and directions described in this application are all explained with reference to the drawings as examples, but they can be changed as needed, and the changes are all included in the protection scope of this application. The drawings of this application are only used to illustrate the relative position relationship and do not represent the true proportion.

[0027] Below, some terms in the embodiments of the present application are explained to facilitate understanding by those skilled in the art.

[0028] Important loads: refers to the air conditioning controller in the air conditioning system, the cooling water pump of the PCS, the multi-way valve and other components.

[0029] Non-critical loads: refers to components such as fans in air-conditioning systems and cooling water pumps in energy storage devices.

[0030] Black start: refers to starting the energy storage cabinet and generating electricity and connecting to the grid without external power supply.

[0031] Grid connection: refers to the transmission and use of electricity generated by new energy power generation devices such as photovoltaic panels or energy storage cabinets after being connected to the power grid.

[0032] Off-grid: refers to photovoltaic panels and other new energy power generation devices being disconnected from the power grid.

[0033] Low voltage ride through: refers to a temporary voltage drop in the power network, that is, the voltage amplitude of the power grid drops below a certain set threshold.

[0034] Reference Figure 1In a microgrid system, new energy generation devices such as photovoltaic panels and energy storage cabinets are usually configured. The photovoltaic inverter is used to convert the power of the photovoltaic panel into AC power and output it to the grid. The energy storage cabinet is equipped with an energy storage device, a power conversion system (PCS) and an air conditioning system. The PCS is used to convert the power stored in the energy storage device into AC power and output it to the grid. The air conditioning system is used to cool the energy storage device and PCS after taking power from the grid to prevent thermal runaway of the energy storage cabinet.

[0035] When photovoltaic panels and other new energy generation devices are not generating electricity, the establishment of the power grid requires the energy storage cabinet to generate electricity and connect to the grid. In this case, starting the energy storage cabinet is an off-grid black start, and the air conditioning system in the energy storage cabinet needs to be started first to avoid thermal runaway and failure of the energy storage cabinet. However, at this time, since the power grid is not established, the air conditioning system cannot draw power from the power grid, causing the air conditioning system to be unable to operate, forming a demand interlock.

[0036] When low voltage ride-through occurs in the power grid, in order to avoid the expansion of the power grid fault, the energy storage cabinet needs to maintain connection with the power grid to support the grid until the grid returns to normal. Therefore, during the low voltage ride-through time, the PCS of the energy storage cabinet must continue to work, which requires the air conditioning system to provide cooling capacity in a short period of time to provide heat dissipation guarantee for the normal operation of the PCS. Similarly, under this working condition, the air conditioning system will be unable to obtain power from the power grid and the air conditioning system operation requirements will be interlocked, resulting in the air conditioning system being unable to operate normally.

[0037] Therefore, in order to solve the problem of demand interlocking in off-grid black start and low voltage ride-through scenarios, refer to Figure 2 , the traditional technical solution usually configures an uninterruptible power supply (UPS) in the energy storage cabinet, and the UPS is usually equipped with a battery. At the initial moment when the energy storage cabinet is connected to the grid, the battery in the UPS is used to power the air conditioning system, which is loop ①. When the air conditioning system is powered on and works normally, it provides cooling for the energy storage device and PCS. After that, the PCS is powered on and works to establish the voltage connection between the energy storage device and the grid, which is loop ②. After the grid connection, the UPS enters the bypass mode, loop ① stops supplying power, and the air conditioning system draws power from the grid, which is loop ③.

[0038] In order to meet the requirement of normal operation of the air-conditioning system in off-grid scenarios and low-voltage ride-through scenarios, the UPS and the batteries in the UPS are configured in the energy storage cabinet, which will increase the size of the energy storage cabinet and increase the cost. In addition, the batteries in the UPS also need frequent maintenance and have low reliability.

[0039] In order to overcome the shortcomings of the above-mentioned traditional technical solutions, the present application provides an energy storage cabinet, which adopts a method of adding an additional low-power power converter between the energy storage device and the air-conditioning system to meet the power supply requirements of the air-conditioning system in the case of low voltage ride-through and off-grid black start. That is, in the case of low voltage ride-through and off-grid black start, the power converter converts the electric energy of the energy storage device to power the air-conditioning system, thereby achieving low-cost support for low voltage ride-through scenarios and off-grid black start scenarios.

[0040] The energy storage cabinet provided in this application is described in detail below with reference to the accompanying drawings.

[0041] Figure 3 A structural schematic diagram of an energy storage cabinet provided in an embodiment of the present application is exemplified.

[0042] Reference Figure 3In an embodiment of the present application, the energy storage cabinet may specifically include: an energy storage device, an energy storage converter, an air conditioning system and a power converter. Among them, the energy storage device is connected to the power grid through the energy storage converter, the energy storage device is connected to the air conditioning system through the power converter, and the air conditioning system is connected to the power grid. The air conditioning system includes: a first load, a conversion circuit and a first power supply circuit. The first power supply circuit has two power supply input ports, wherein the first input end ① of the first power supply circuit is connected to the conversion circuit, the second input end ② of the first power supply circuit is connected to the power converter, and the output end of the first power supply circuit is connected to the first load. The conversion circuit is connected to the power grid, and the conversion circuit is used to convert the alternating current provided by the power grid into a first voltage and provide it to the first power supply circuit when the voltage amplitude of the power grid is greater than the set threshold, that is, when the power grid is normal; the power converter is used to convert the electric energy of the energy storage device into a second voltage and provide it to the first power supply circuit, and the second voltage is lower than the first voltage. In this way, when the power grid is normal, since the first voltage of the first input end ① of the first power supply circuit is higher than the second voltage of the second input end ②, the power converter connected to the second input end ② is in a standby state, and the first power supply circuit draws power from the power grid through the conversion circuit. When an abnormality occurs in the power grid (i.e., low voltage ride-through), the conversion circuit connected to the first input terminal ① loses power, causing the output of the conversion circuit to drop from the first voltage to a voltage lower than the second voltage. The first power supply circuit draws power from the energy storage device through the power converter, which can ensure that the first power supply circuit provides uninterrupted power to the first load, so that the first load works uninterruptedly under the drive of the first power supply circuit, thereby ensuring that the air-conditioning system continues to cool the energy storage cabinet. During the continuous operation of the first load, the energy storage converter can convert the electric energy of the energy storage device into AC power and output it to the power grid to maintain the connection between the energy storage cabinet and the power grid during the low voltage ride-through. Alternatively, when there is no electricity in the power grid, i.e., when the power grid is off-grid and black-started, the first power supply circuit directly draws power from the energy storage device through the power converter, starts the first load to work, and starts to cool the energy storage cabinet. After the first load works, the energy storage converter can be started to convert the electric energy of the energy storage device into AC power and output it to the power grid to support the off-grid black-start.

[0043] In the present application, only during low voltage ride-through or off-grid black start, a power converter arranged between the energy storage device and the air-conditioning system is used to provide a second voltage to the first power supply circuit. After the grid voltage is normal or after the startup is completed, the first power supply circuit uses a conversion circuit to draw power from the grid. Since the working time of the power converter is very short, the power converter can use a DC-to-DC circuit (DC / DC) with a small rated power and large transient power support to achieve its power conversion function. In addition, the power converter occupies a small volume, and the power converter can be integrated in the driving auxiliary source module of the air-conditioning system, that is, the power converter can be integrated in the same module as the conversion circuit, or the power converter can also be arranged outside the air-conditioning system, for example, integrated in a module for collecting and controlling the energy balance of the energy storage device, and the added power converter will not occupy too much space in the energy storage cabinet.

[0044] Embodiment 1:

[0045] Reference Figure 3In this embodiment, the DC load in the air-conditioning system can be divided into important loads and non-important loads. The important load, i.e., the first load, can specifically include components such as the air-conditioning controller, the cooling water pump of the energy storage converter, and the multi-way valve. The non-important load, i.e., the second load, can include components such as the fan and the cooling water pump of the energy storage device. The air-conditioning controller can provide a driving signal to components such as the cooling water pump, the fan, and the multi-way valve in the air-conditioning system to control their working state. The multi-way valve is used to connect multiple pipes in the air-conditioning system. The multi-way valve can include valves such as a three-way valve and a four-way valve. By changing the valve core state of the multi-way valve, the water flow path in the pipe can be changed. Multiple fans can be set in the air-conditioning system, for example, a fan for exhausting air facing the energy storage device, a fan for exhausting air facing the energy storage converter, and a dehumidification fan. The output of the conversion circuit can be divided into two different DC power supply circuits, i.e., a first power supply circuit and a second power supply circuit. The first power supply circuit is used to power the important load, and the second power supply circuit is used to power the non-important load. Since the power of important loads is relatively small, generally accounting for less than 10% of the total power of the air-conditioning system, the added power converter only needs to meet the requirements of large transient power and small rated power. The first power supply circuit has an additional second input terminal ② connected to the power converter compared to the second power supply circuit. During off-grid or low-voltage ride-through, the first power supply circuit draws power from the energy storage device through the power converter to support the operation of important loads to provide partial cooling capacity, such as providing cooling capacity for the energy storage converter and providing heat dissipation guarantee for the energy storage converter, thereby supporting the energy storage converter to establish grid connection between the energy storage device and the power grid. Since the second power supply circuit only draws power from the power grid through the conversion circuit, during off-grid or low-voltage ride-through, the grid voltage is not enough to support the second power supply circuit to power non-important loads, and non-important loads stop working. In addition, the air-conditioning system may also include an AC load, namely a compressor, and the conversion circuit may also convert the power grid into the AC power required by the compressor. During off-grid or low-voltage ride-through, the grid voltage is not enough to support the conversion circuit to power the compressor, so the compressor stops working.

[0046] Reference Figure 4In this embodiment, the conversion circuit may specifically include a rectifier circuit (AC / DC), a direct current conversion circuit (DC / DC) and an inverter circuit (DC / AC). The input end of the rectifier circuit is connected to the power grid, and the output end of the rectifier circuit is respectively connected to the input end of the direct current conversion circuit and the input end of the inverter circuit. The rectifier circuit is used to convert the alternating current provided by the power grid into a high-voltage direct current output when the power grid is normal. For example, the rectifier circuit converts 220V alternating current into a high-voltage direct current output of 420V. The first output end of the direct current conversion circuit is connected to the first input end ① of the first power supply circuit, and the second output end of the direct current conversion circuit is connected to the second load through the second power supply circuit. The direct current conversion circuit is used to convert the high-voltage direct current provided by the rectifier circuit into a low-voltage direct current output when the power grid is normal. For example, the direct current conversion circuit converts 420V high-voltage direct current into a low-voltage direct current output of 14V. The output end of the power converter is connected to the second input end ② of the first power supply circuit. The power converter is used to convert the high-voltage electric energy stored in the energy storage device into a low-voltage direct current output. For example, the power converter converts the 800V high-voltage electric energy of the energy storage device into a low-voltage direct current output of 13V. In this way, since the power converter converts the high-voltage electric energy into a low-voltage direct current output, it is beneficial to save the energy consumption of the power converter when it is in a standby state when the power grid is normal. The output end of the inverter circuit is connected to the compressor. The inverter circuit is used to convert the high-voltage direct current provided by the rectifier circuit into an alternating current output when the power grid is normal.

[0047] In this embodiment, in order to prevent the second voltage of the first power supply circuit from flowing back from the first input terminal ① to the DC conversion circuit (also known as the reverse injection phenomenon) and damaging the circuit when the grid is off-grid black start or low voltage ride-through occurs, a first anti-reverse connection circuit (oring circuit) can be set between the first output terminal of the DC conversion circuit and the first input terminal ① of the first power supply circuit. The first anti-reverse connection circuit can ensure the unidirectional flow of current from the conversion circuit to the first input terminal ① of the first power supply circuit, that is, it can prevent the current from the first input terminal ① of the first power supply circuit to the reverse flow of the conversion circuit. Exemplarily, the first anti-reverse connection circuit can specifically use a parallel switch tube and a diode to realize its function.

[0048] In this embodiment, in order to prevent the first voltage of the first power supply circuit from flowing back from the second input terminal ② to the power converter and damaging the device when the power grid is normal, a second anti-reverse connection circuit (oring circuit) can be set between the output terminal of the power converter and the second input terminal ② of the first power supply circuit. The second anti-reverse connection circuit can ensure the unidirectional flow of current from the power converter to the second input terminal ② of the first power supply circuit, that is, it can prevent the current from flowing in the reverse direction from the second input terminal ② of the first power supply circuit to the power converter. Exemplarily, the second anti-reverse connection circuit can specifically use a diode to realize its function.

[0049] The working states of this embodiment under different working conditions of the power grid are as follows:

[0050] Phase 1: When the 220V AC voltage of the power grid is normally supplied, the first voltage of the first input terminal ① of the first power supply circuit is higher than the second voltage of the second input terminal ②, the DC conversion circuit connected to the first input terminal ① supplies power to the first power supply circuit, the second input terminal ② is cut off, and the power converter connected to the second input terminal ② is in standby state. The DC conversion circuit supplies power to important loads and non-important loads through the first power supply circuit and the second power supply circuit respectively, the inverter circuit supplies power to the compressor, the loads in the air-conditioning system are all working, and the air-conditioning system provides full cooling and heat dissipation functions.

[0051] The second stage: when off-grid black start or low voltage ride-through occurs in the grid, the 220V AC voltage of the grid is cut off, the voltage of the first input terminal ① of the first power supply circuit drops from the first voltage to 0V, the voltage of the first input terminal ① is lower than the second voltage of the second input terminal ②, the second input terminal ② starts to supply power to the first power supply circuit, and the first input terminal ① is cut off. At this time, only the first power supply circuit supplies power to important loads, the non-important loads and compressor of the air-conditioning system stop working, only the important loads work, and the air-conditioning system can provide partial cooling and heat dissipation functions.

[0052] Phase 3: After successful startup or low-voltage ride-through of the power grid, the power grid establishes a 220V AC voltage, the first voltage of the first input terminal ① of the first power supply circuit is higher than the second voltage of the second input terminal ②, the DC conversion circuit connected to the first input terminal ① starts to supply power to the first power supply circuit, the second input terminal ② is cut off, and the power converter connected to the second input terminal ② resumes standby mode. The DC conversion circuit supplies power to important loads and non-important loads through the first power supply circuit and the second power supply circuit respectively, the inverter circuit supplies power to the compressor, the loads in the air-conditioning system are all working, and the air-conditioning system provides full cooling and heat dissipation functions.

[0053] Reference Figure 5 , taking the cooling water pump of the energy storage inverter in the air-conditioning system as an example, the actual signal waveforms corresponding to the above three stages are tested. In the first stage: the DC conversion circuit provides a first voltage to the first input terminal ① of the first power supply circuit, the power supply voltage of the water pump is 14V, and the water pump can operate normally. In the second stage: switch to the power converter to provide a second voltage to the second input terminal ② of the first power supply circuit, the power supply voltage of the water pump is 13V, and the water pump can operate normally. In the third stage: switch to the DC conversion circuit to provide a first voltage to the first input terminal ① of the first power supply circuit, the power supply voltage of the water pump is 14V, and the water pump can operate normally.

[0054] Embodiment 2:

[0055] Reference Figure 6 and Figure 7In this embodiment, in the air-conditioning system, no distinction is made between important loads and non-important loads, that is, all loads in the air-conditioning system, that is, the first loads, are powered by the first power supply circuit. The first load includes: an air-conditioning controller, a multi-way valve, a cooling water pump of an energy storage converter, a cooling water pump and a fan of an energy storage device, and other DC loads, as well as an AC load such as a compressor. When the power grid is normal, the conversion circuit can supply power to the first power supply circuit to meet the normal operation of all loads. When off-grid black start or low-voltage crossing occurs in the power grid, the power converter is switched to supply power to the first power supply circuit to meet the short-term normal operation of all loads. After waiting for the power grid to be normal, the conversion circuit is switched to supply power to the first power supply circuit.

[0056] Reference Figure 6 and Figure 7 In this embodiment, the conversion circuit may specifically include a rectifier circuit (AC / DC), and the first power supply circuit includes a direct current conversion circuit (DC / DC) and an inverter circuit (DC / AC). Among them, the input end of the rectifier circuit is connected to the power grid, and the output end of the rectifier circuit is connected to the first input end ① of the high-voltage bus. The rectifier circuit is used to convert the alternating current provided by the power grid into a high-voltage direct current output when the power grid is normal. For example, the rectifier circuit converts 220V alternating current into a 420V high-voltage direct current output. A second input end ② is set on the high-voltage bus for connection with the output end of the power converter. The power converter is used to convert the high-voltage electric energy stored in the energy storage device into a high-voltage direct current output. For example, the power converter converts the 800V high-voltage electric energy of the energy storage device into a 410V high-voltage direct current output. The output end of the high-voltage bus is respectively connected to the input end of the direct current conversion circuit and the input end of the inverter circuit. When the power grid is normal, the high-voltage bus outputs the high-voltage direct current provided by the rectifier circuit. During off-grid or low-voltage ride-through, the high-voltage bus outputs the high-voltage direct current provided by the power converter. The output end of the DC conversion circuit is connected to the DC load, and the DC conversion circuit is used to convert the high-voltage DC power provided by the high-voltage bus into a low-voltage DC power output. For example, the DC conversion circuit converts 420V or 410V high-voltage DC power into a 14V low-voltage DC power output. The output end of the inverter circuit is connected to the compressor, and the inverter circuit is used to convert the high-voltage DC power provided by the high-voltage bus into an AC power output. For example, the inverter circuit converts 420V or 410V high-voltage DC power into an AC power output.

[0057] In this embodiment, in order to prevent the second voltage transmitted on the high-voltage bus from flowing back from the first input terminal ① to the rectifier circuit and damaging the circuit when off-grid black start or low-voltage crossing occurs in the power grid, a first anti-reverse connection circuit (oring circuit) can be set between the output end of the rectifier circuit and the high-voltage bus. By way of example, the first anti-reverse connection circuit can specifically use parallel switching tubes and diodes to achieve its function.

[0058] In this embodiment, in order to prevent the first voltage transmitted on the high-voltage bus from flowing back from the second input terminal ② to the power converter and damaging the device when the power grid is normal, a second anti-reverse connection circuit (oring circuit) can be set between the output terminal of the power converter and the high-voltage bus. By way of example, the second anti-reverse connection circuit can specifically use parallel switching tubes and diodes to achieve its function.

[0059] The working states of this embodiment under different working conditions of the power grid are as follows:

[0060] Phase 1: When the 220V AC voltage of the power grid is normally supplied, the first voltage of the first input terminal ① of the first power supply circuit is higher than the second voltage of the second input terminal ②, the rectifier circuit connected to the first input terminal ① supplies power to the high-voltage bus, the second input terminal ② is cut off, and the power converter connected to the second input terminal ② is in standby mode. The DC conversion circuit supplies power to all DC loads, the inverter circuit supplies power to the compressor, the loads in the air-conditioning system are all working, and the air-conditioning system provides full cooling and heat dissipation functions.

[0061] The second stage: when off-grid black start or low voltage ride-through occurs in the grid, the 220V AC voltage of the grid is cut off, the voltage of the first input terminal ① of the first power supply circuit drops from the first voltage to 0V, the voltage of the first input terminal ① is lower than the second voltage of the second input terminal ②, the second input terminal ② starts to supply power to the high-voltage bus, and the first input terminal ① is cut off. The DC conversion circuit supplies power to all DC loads, the inverter circuit supplies power to the compressor, the loads in the air-conditioning system are all working, and the air-conditioning system provides full cooling and heat dissipation functions.

[0062] Phase 3: After successful startup or low-voltage ride-through of the power grid, the power grid establishes a 220V AC voltage, the first voltage of the first input terminal ① of the first power supply circuit is higher than the second voltage of the second input terminal ②, the rectifier circuit connected to the first input terminal ① starts to supply power to the first power supply circuit, the second input terminal ② is cut off, and the power converter connected to the second input terminal ② resumes standby mode. The DC conversion circuit supplies power to all DC loads, the inverter circuit supplies power to the compressor, the loads in the air-conditioning system are all working, and the air-conditioning system provides full cooling and heat dissipation functions.

[0063] The energy storage cabinet provided in the embodiment of the present application adopts the method of adding an additional power converter between the energy storage device and the air conditioning system to meet the power supply demand of the air conditioning system in the case of low voltage ride-through and off-grid black start. In the case of low voltage ride-through and off-grid black start, the power storage device is converted by the power converter to power the air conditioning system. After the grid voltage is normal or the startup is completed, the conversion circuit in the air conditioning system is used to draw power from the grid. Since the working time of the power converter is very short, the power converter can adopt a DC-to-DC circuit with a small rated power and a large transient power support to achieve low-cost support for low voltage ride-through scenarios and off-grid black start scenarios.

[0064] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. An energy storage cabinet, characterized in that: include: Energy storage devices, energy storage converters, air conditioning systems and power converters; among them, The energy storage device is connected to the power grid via the energy storage converter, the energy storage device is connected to the air conditioning system via the power converter, and the air conditioning system is connected to the power grid; The air conditioning system comprises: a first load, a conversion circuit and a first power supply circuit, wherein a first input end of the first power supply circuit is connected to the conversion circuit, a second input end of the first power supply circuit is connected to the power converter, an output end of the first power supply circuit is connected to the first load, and the conversion circuit is connected to the power grid; The conversion circuit is used for converting the AC power provided by the power grid into a first voltage and providing it to the first power supply circuit when the voltage amplitude of the power grid is greater than a set threshold; The power converter is used to convert the electric energy of the energy storage device into a second voltage and provide it to the first power supply circuit, wherein the first voltage is higher than the second voltage; The first load is used to work under the drive of the first power supply circuit; The energy storage converter is used to convert the electric energy of the energy storage device into alternating current and output it to the power grid after the first load is working.

2. The energy storage cabinet according to claim 1, characterized in that: The conversion circuit includes a rectifier circuit and a DC conversion circuit. The input end of the rectifier circuit is connected to the power grid, the output end of the rectifier circuit is connected to the input end of the DC conversion circuit, and the first output end of the DC conversion circuit is connected to the first input end of the first power supply circuit.

3. The energy storage cabinet according to claim 2, characterized in that: The air conditioning system further includes: a second load and a second power supply circuit, and the second output end of the DC conversion circuit is connected to the second load through the second power supply circuit.

4. The energy storage cabinet according to claim 3, characterized in that: The first load includes: an air conditioning controller, a multi-way valve and a cooling water pump of an energy storage converter; The second load includes: a cooling water pump and a fan of the energy storage device.

5. The energy storage cabinet according to any one of claims 2 to 4, characterized in that: The air conditioning system further includes a compressor, and the conversion circuit further includes an inverter circuit, the input end of the inverter circuit is connected to the output end of the rectifier circuit, and the output end of the inverter circuit is connected to the compressor.

6. The energy storage cabinet according to claim 1, characterized in that: The conversion circuit includes a rectifier circuit, and the first power supply circuit includes a DC conversion circuit; The input end of the rectifier circuit is connected to the power grid, the output end of the rectifier circuit is connected to the input end of the DC conversion circuit, and the output end of the DC conversion circuit is connected to the first load; The output end of the power converter is connected to the input end of the DC conversion circuit.

7. The energy storage cabinet according to claim 6, characterized in that: The first load includes: an air conditioning controller, a multi-way valve, a cooling water pump of an energy storage converter, a cooling water pump of an energy storage device, and a fan.

8. The energy storage cabinet according to claim 6 or 7, characterized in that: The first load further includes a compressor, and the first power supply circuit further includes an inverter circuit; The input end of the inverter circuit is connected to the output end of the rectifier circuit and the output end of the power converter respectively, and the output end of the inverter circuit is connected to the compressor.

9. The energy storage cabinet according to claim 1, 2, 3, 4, 6 or 7, characterized in that: The air conditioning system also includes a first anti-reverse connection circuit arranged between the conversion circuit and the first input end of the first power supply circuit, and the first anti-reverse connection circuit is used to ensure unidirectional flow of current from the conversion circuit to the first input end of the first power supply circuit.

10. The energy storage cabinet according to claim 1, 2, 3, 4, 6 or 7, characterized in that: Also includes: A second anti-reverse connection circuit is provided between the power converter and the second input end of the first power supply circuit, and the second anti-reverse connection circuit is used to ensure unidirectional flow of current from the power converter to the second input end of the first power supply circuit.

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