An energy storage system

Abstract

This application provides an energy storage system, which may include an energy storage module and an energy conversion module. The energy storage module is connected to the energy conversion module via a DC bus, and the energy storage module and the energy conversion module are connected in parallel. Here, the energy storage module can also be referred to as an energy storage container, and the energy conversion module can also be referred to as an energy conversion system. The aforementioned energy storage module can generate a target waveform signal on the DC bus when a black-start signal is received. At this time, the energy conversion module can detect the target waveform signal on the DC bus and start operation based on the target waveform signal. It can be understood that even when the power-on command of the energy management system cannot be received, the energy conversion module can also actively start operation upon detecting the target waveform signal on the DC bus, achieving a black start. In this application, black start can be achieved by the energy conversion module actively starting operation upon detecting the target waveform signal on the DC bus, which is low-cost and has wider applicability.

Description

Technical Field

[0001] This application relates to the field of battery energy storage technology, and in particular to an energy storage system. Background Technology

[0002] In energy storage systems, multiple battery modules can be connected in series to form multiple battery clusters, and multiple battery clusters can be connected in parallel to supply power to the load.

[0003] Currently, pressing the black start button allows multiple parallel battery clusters to power an auxiliary power supply to start the energy storage system. For large-scale energy storage systems, an uninterrupted power supply (UPS) can be configured to power the system controller to start the system, but this is costly. Furthermore, when the energy storage network is not yet fully constructed or the system controller lacks power, the distance between the system controller and other controllers in the energy storage system prevents communication. Consequently, the grid-connected power conversion system (PCS, such as a DC / AC inverter) cannot receive the start-up signal, leading to black start failure and ultimately preventing the energy storage system from powering the load. Summary of the Invention

[0004] This application provides an energy storage system that can achieve black start by starting the system when the target waveform signal of the DC bus is detected through the energy conversion unit. This system is low in cost and has wider applicability.

[0005] Firstly, this application provides an energy storage system, which may include an energy storage module and an energy conversion module. The energy storage module is connected to the energy conversion module via a DC bus, and the energy storage module and the energy conversion module are connected in parallel. Here, the energy storage module can also be referred to as an energy storage container, and the energy conversion module can also be referred to as an energy conversion system. The energy storage module can generate a target waveform signal on the DC bus upon receiving a black-start signal. The waveform of the target waveform signal can be a preset waveform, which can be a waveform set by the user or a waveform configured in the energy storage system's database. The energy conversion module can detect the target waveform signal on the DC bus and start operation based on the target waveform signal. It can be understood that, in the absence of a power-on command from the energy management system (EMS), the energy conversion module can start operation upon detecting the target waveform signal on the DC bus, achieving a black start. In this application, the energy conversion module can actively start operation upon detecting the target waveform signal on the DC bus to achieve a black start for the energy storage system, resulting in lower cost and wider applicability.

[0006] In conjunction with the first aspect, in a first possible implementation, the energy storage module may include an energy storage unit, a battery control unit, and a DC / DC conversion unit (also referred to as a DC / DC converter), with the energy storage unit and the DC / DC conversion unit connected in parallel. The energy storage unit can be used to provide a DC input voltage to the DC / DC conversion unit. The energy storage unit may include at least one battery cluster, and the battery control unit may also be referred to as a battery control unit (BCU). The battery control unit can be used to send a black-start signal to the DC / DC conversion unit when a black-start command is detected. The DC / DC conversion unit can be used to receive the black-start signal from the battery control unit and generate a target waveform signal on the DC bus. In the energy storage system provided in this application, a target waveform signal with a preset waveform can be generated based on the DC / DC conversion unit, so that the energy conversion module actively starts working when the target waveform signal is detected to achieve the black start of the energy storage system, resulting in lower cost and wider applicability.

[0007] In conjunction with the first possible implementation of the first aspect, in a second possible implementation, the energy storage module may further include a black-start unit, which can be connected to the energy storage unit. This black-start unit (such as a black-start button or black-start switch) can be used to generate a black-start command. When the black-start command is detected, the energy storage unit can feed back the black-start command to the battery control unit. In the energy storage system provided in this application, the black-start command can be fed back to the battery control unit based on the energy storage unit, thereby realizing the black-start of the energy storage system through the DC / DC conversion unit and the energy conversion module, resulting in lower cost and wider applicability.

[0008] In a third possible implementation, combining the first or second possible implementation of the first aspect, the DC / DC converter unit can be used to perform open-loop control of the reference voltage of the DC bus to generate a target waveform signal on the DC bus. The reference voltage here can be a user-set DC bus voltage value or the default DC bus voltage value configured in the energy storage system. In the energy storage system provided in this application, a target waveform signal with a preset waveform can be generated based on the open-loop control of the DC / DC converter unit, so that the energy conversion module actively starts working when it detects the target waveform signal to achieve a black start for the energy storage system, resulting in lower cost and wider applicability.

[0009] In a fourth possible implementation, combining the first or second possible implementation of the first aspect, the DC / DC conversion unit may include a bus voltage loop. This DC / DC conversion unit can be used to acquire the feedback voltage of the DC bus and perform closed-loop control of the reference voltage and feedback voltage of the DC bus based on the bus voltage loop to generate a target waveform signal on the DC bus. In the energy storage system provided in this application, a target waveform signal with a preset waveform can be generated based on the closed-loop control of the DC / DC conversion unit, so that the energy conversion module actively starts working when it detects the target waveform signal to achieve black start of the energy storage system, resulting in lower cost and wider applicability.

[0010] In a fifth possible implementation, in conjunction with any one of the first to fourth possible implementations of the first aspect, a bus capacitor may be included on the DC bus, and the bus capacitor is connected in parallel with the DC / DC conversion unit.

[0011] In conjunction with the fifth possible implementation of the first aspect, in the sixth possible implementation, the target waveform signal is the waveform signal of the voltage across the bus capacitor.

[0012] In a seventh possible embodiment, in conjunction with any one of the first to fourth possible embodiments of the first aspect, the DC bus includes a bus inductor connected in series with the DC / DC conversion unit.

[0013] In conjunction with the seventh possible implementation of the first aspect, in the eighth possible implementation, the target waveform signal is the waveform signal of the current flowing through the bus inductor.

[0014] In conjunction with any of the first to eighth possible embodiments of the first aspect, in the ninth possible embodiment, the energy conversion module can be a DC / AC conversion unit (also called a DC / AC converter), and the output terminal of the DC / AC conversion unit can be used to connect to an AC power grid or an AC load. The DC / AC conversion unit is also used to convert the DC power output by the energy storage module into AC power when the output terminal is connected to an AC power grid or an AC load, thereby supplying power to the AC power grid or AC load. In the energy storage system provided in this application, after the DC / AC conversion unit is actively turned on, it can supply power to the AC power grid or AC load, thus offering greater applicability.

[0015] In this application, even when the power-on command from the energy management system cannot be received, the energy conversion module can also actively start working when the target waveform signal of the DC bus is detected, thereby realizing the black start of the energy storage system, which is lower in cost and more applicable. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the application scenario of the energy storage system provided in this application;

[0017] Figure 2 This is a structural schematic diagram of the energy storage system provided in this application;

[0018] Figure 3 This is another structural schematic diagram of the energy storage system provided in this application;

[0019] Figure 4 This is a schematic diagram of the working process of the battery control unit provided in this application;

[0020] Figure 5 This is a schematic diagram of the working process of the DC / DC conversion unit provided in this application;

[0021] Figure 6 This is a schematic diagram illustrating the working principle of the DC / AC conversion unit provided in this application;

[0022] Figure 7 This is another structural schematic diagram of the energy storage system provided in this application;

[0023] Figure 8 This is a waveform diagram of the target waveform signal provided in this application;

[0024] Figure 9 This is a power supply diagram of the energy storage system provided in this application. Detailed Implementation

[0025] The energy storage system provided in this application is applicable to various types of power generation equipment, such as photovoltaic power generation equipment or wind power generation equipment, as well as different types of electrical equipment (such as power grids, household appliances, or industrial and commercial electrical equipment). It can be applied in the automotive field or microgrid field. The energy storage system provided in this application is applicable to energy storage of different types of energy storage units. Here, the components in different types of energy storage units may include lithium-ion batteries, lead-acid batteries (or lead-acid storage batteries), and supercapacitors (also known as electrochemical capacitors), etc. This application does not specifically limit the specific types of components in the energy storage unit. For ease of description, this application will use a battery as an example to illustrate the energy storage system provided in this application.

[0026] The energy storage system provided in this application may include an energy storage module and an energy conversion module. The energy storage module is connected to the energy conversion module via a DC bus, and the energy storage module and the energy conversion module are connected in parallel. The energy conversion module can also be referred to as the energy conversion system. Upon receiving a black-start signal, the energy storage module generates a target waveform signal on the DC bus. The waveform of the target waveform signal can be a preset waveform, which can be a waveform stored in the energy conversion module, or a waveform set by the user. The energy conversion module can detect the target waveform signal on the DC bus and start operation based on the target waveform signal. It can be understood that, in the absence of a power-on command from the energy management system, the energy conversion module can actively start operation upon detecting the target waveform signal on the DC bus, thus achieving a black start for the energy storage system. The energy storage system provided in this application can achieve a black start by actively starting operation upon detecting the target waveform signal on the DC bus through the energy conversion module, resulting in lower cost and wider applicability. The energy storage system provided in this application can be adapted to different application scenarios, such as photovoltaic power generation, wind power generation, or electrical equipment power supply scenarios. The following explanation will use the electrical equipment power supply scenario as an example, and will not be elaborated further.

[0027] Please see also Figure 1 , Figure 1 This is a schematic diagram illustrating the application scenario of the energy storage system provided in this application. For example... Figure 1 As shown, an energy storage system (such as energy storage system 1) may include an energy storage container and a DC / AC converter. The energy storage container may include at least one battery cluster and a DC / DC converter, with the battery clusters connected in parallel. A battery cluster may consist of multiple battery groups connected in series. This battery group may be a battery pack, which may consist of one or more battery cells (the voltage of which is typically between 2.5V and 4.2V) connected in series and parallel to form a minimum energy storage and management unit. It can be understood that at least one battery cluster can provide a DC input voltage to the DC / DC converter. The DC / DC converter performs power conversion on the DC input voltage and outputs DC power. Then, the DC / AC converter enables energy exchange between the energy storage battery and the AC power grid (such as grid 2) or between the energy storage battery and an AC load (such as household appliance 3). After energy storage system 1 is started, the energy storage container can output DC power to the DC / AC converter. The DC / AC converter can perform power conversion on the DC power provided by the energy storage container and output AC power to grid 2 or household appliance 3 to supply power to grid 2 and household appliance 3.

[0028] The following will combine Figures 2 to 9 The energy storage system provided in this application and its working principle are illustrated with examples.

[0029] See Figure 2 , Figure 2This is a structural schematic diagram of the energy storage system provided in this application. Figure 2 As shown, the energy storage system 1 may include an energy storage module 10 and an energy conversion module 20. The energy storage module 10 is connected to the energy conversion module 20 via a DC bus 30. Upon receiving a black-start signal, the energy storage module 10 generates a target waveform signal on the DC bus 30. This target waveform signal can be a preset waveform, either user-defined or configured in the energy storage system's database. The energy conversion module 20 can detect the target waveform signal on the DC bus in real time and start operation based on the target waveform signal. It can be understood that the energy conversion module 20 can actively start operation based on the detected target waveform signal to achieve a black start for the energy storage system 1, even without receiving a start-up command. Please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is another structural schematic diagram of the energy storage system provided in this application. For example... Figure 3 As shown, Figure 2 The energy storage module 10 shown may include an energy storage unit 101, a DC / DC converter unit 102, and a battery control unit 103. The energy storage unit 101 may be connected in parallel with the DC / DC converter unit 102. The energy storage unit 101 may include one or more battery clusters (i.e., at least one battery cluster), with each battery cluster connected in parallel. One battery cluster may consist of multiple battery groups connected in series. The energy storage unit 101 can provide a DC input voltage to the DC / DC converter unit 102. The DC / DC converter unit may be one or more functional modules or hardware devices within the energy storage module 10; it may also be referred to as a DC / DC converter. The circuit topology used by the DC / DC converter unit may be a flying capacitor multilevel circuit, a three-level boost circuit, or a four-switch buck-boost circuit, etc., which can be determined according to the actual application scenario requirements and is not limited here.

[0030] In some feasible implementations, such as Figure 2 The energy storage module 10 shown may also include a black-start unit 104, which can be directly or indirectly connected to the battery control unit 103. The battery control unit 103 can communicate with the energy storage unit 101 and the DC / DC conversion unit 102 via a communication line. Assuming the black-start unit 104 is a black-start button, when the user presses the black-start button, the button can detect the press command and generate a black-start command. Assuming the black-start unit 104 is a black-start switch, when the black-start switch is on, it can generate a black-start command. Figure 3 As shown, the black start unit 104 can be connected to the energy storage unit 101 to achieve connection with the battery control unit 103. When the energy storage unit 101 detects the black start command generated by the black start unit 104, it can send the black start command back to the battery control unit 103 via the communication line. Please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a schematic diagram of the working process of the battery control unit provided in this application. Figure 4 As shown, after the battery control unit 103 starts, when it detects a black start command from the energy storage unit 101, it sends a black start signal to the DC / DC converter unit 102 via the communication line. Optionally, the black start unit 104 can also be directly connected to the battery control unit 103. When the battery control unit 103 detects a black start command generated by the black start unit 104, it can send a black start signal to the DC / DC converter unit 102 via the communication line. The specific method can be determined according to the actual application scenario and is not limited here. Conversely, if the battery control unit 103 does not detect a black start command, it terminates its operation.

[0031] In some feasible implementations, the DC / DC conversion unit 102 may include multiple switches. These switches may be insulated gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), or diodes made of silicon semiconductor materials (Si), third-generation wide-bandgap semiconductor materials (silicon, Si), gallium nitride (GaN), diamond, zinc oxide (ZnO), or other materials. The specific type can be determined according to the actual application scenario and is not limited here. Please refer to [further details omitted]. Figure 5 , Figure 5 This is a schematic diagram of the working process of the DC / DC conversion unit provided in this application. For example... Figure 5 As shown, after the DC / DC converter unit 102 is started, it can detect the black start signal sent by the battery control unit 103 in real time. When the black start signal is detected, the unit starts up and controls the on or off of the aforementioned switches to generate the target waveform signal on the DC bus 30. Conversely, if the DC / DC converter unit 102 does not detect the black start signal sent by the battery control unit 103, it stops working.

[0032] In some feasible implementations, the DC / DC converter unit 102 can perform open-loop control of the reference voltage of the DC bus 30 to control the on or off of the aforementioned switches, thereby generating a target waveform signal on the DC bus 30. The reference voltage here can be the DC bus voltage value set by the user or the DC bus voltage value configured by default in the energy storage system. Open-loop control here refers to a system control method without feedback information. After the DC / DC converter unit 102 is turned on and enters the operating state, it can generate a target waveform signal on the DC bus 30 based on the reference voltage of the DC bus 30. The target waveform signal on the DC bus 30 is consistent with or the same as the waveform signal of the output voltage or output current of the DC / DC converter unit 102.

[0033] In some feasible implementations, the DC / DC converter unit 102 may include a bus voltage loop. The DC / DC converter unit 102 can acquire the feedback voltage of the DC bus 30 in real time and perform closed-loop control on the reference voltage and feedback voltage of the DC bus 30 based on the bus voltage loop to control the on or off of the aforementioned switches, thereby generating a target waveform signal on the DC bus 30. The bus voltage loop can be used to adjust the output voltage of the DC / DC converter unit 102. In this application, the actual output voltage of the DC bus 30 acquired by the DC / DC converter unit 102 can be collectively referred to as the feedback voltage. Closed-loop control (also known as negative feedback control) refers to a system control method with feedback information (such as feedback voltage). Closed-loop control is a control method that extracts a control signal from the change in the output quantity (such as the output voltage of the DC / DC converter unit 102, i.e., the aforementioned feedback voltage) as a comparison quantity and feeds it back to the input terminal to control the input quantity. It is understood that when the DC / DC conversion unit 102 detects a deviation between the feedback voltage and the reference voltage (i.e., the feedback voltage and the reference voltage are different, or the difference between the feedback voltage and the reference voltage is greater than the voltage deviation value), it extracts a control signal from the real-time acquired feedback voltage and controls the conduction or deactivation of the aforementioned switches based on the control signal to generate a target waveform signal on the DC bus 30. The voltage deviation value here can be a user-set voltage value or a default voltage value configured in the energy storage system 1. A '1' in the control signal can indicate that the switch is on, and a '0' in the control signal can indicate that the switch is off.

[0034] Optionally, in some feasible implementations, the system controller of the energy storage system 1 can generate switch control signals for controlling each switch in the DC / DC converter unit 102, and control the switching on or off of each switch in the DC / DC converter unit 102 based on the switch control signals. The switch control signals here can be pulse width modulation (PWM) signals of each switch in the DC / DC converter unit 102, which can be simply referred to as PWM signals. For example, a 1 in the PWM signal can represent the switch being on, and a 0 in the PWM signal can represent the switch being off. In this case, the DC / DC converter unit 102 can generate a target waveform signal on the DC bus 30 based on the on or off state of each switch.

[0035] In some feasible implementations, the aforementioned DC bus 30 may include a bus capacitor or a bus inductor, which can be determined according to the actual application scenario and is not limited here. The aforementioned DC bus 30 may include a bus capacitor, and this bus capacitor is connected in parallel with the DC / DC converter unit 102; in other words, the bus capacitor can be connected in parallel across the output terminals of the DC / DC converter unit 102. This application can collectively refer to all capacitors (such as one or more capacitors) connected in series on the DC bus as bus capacitors. Assuming the DC bus 30 includes one bus capacitor, this bus capacitor can be directly connected in parallel with the DC / DC converter unit 102; assuming the DC bus 30 includes multiple bus capacitors, these multiple bus capacitors can be connected in series and then in parallel across the output terminals of the DC / DC converter unit 102. In this case, the DC bus 30 may have multiple bus capacitors connected in series in parallel. The target waveform signal in this case can be the waveform signal of the voltage across the bus capacitor (such as the aforementioned one or more capacitors) (i.e., the waveform signal of the voltage on the DC bus 30).

[0036] In some feasible implementations, the DC bus 30 may also include a bus inductor, and the bus inductor may be connected in series with the DC / DC converter unit 102. This application refers to all inductors connected in series on the DC bus (such as one or more inductors) collectively as bus inductors. Assuming the DC bus 30 includes one bus inductor, this bus inductor can be directly connected in series with the DC / DC converter unit 102; assuming the DC bus 30 includes multiple bus inductors, these multiple bus inductors can be connected in series and then connected in series with the DC / DC converter unit 102. In this case, the DC bus 30 can be composed of multiple bus inductors connected in series. The target waveform signal in this case is the waveform signal of the current flowing through the bus inductor (such as the one or more inductors mentioned above) (i.e., the waveform signal of the current on the DC bus 30).

[0037] In some feasible implementations, such as Figure 3 As shown, Figure 2The energy conversion module 20 shown can be a DC / AC conversion unit 201. This DC / AC conversion unit 201 can be one or more functional modules or hardware devices within the energy conversion module 20. The DC / AC conversion unit 201 can also be called a DC / AC converter. The DC / AC conversion unit 201 can be connected in parallel with the DC / DC conversion unit 102. The circuit topology used in the DC / AC conversion unit 201 can be a neutral point clamped T-type three-level circuit, a neutral point clamped circuit (NPC), an active neutral point clamped circuit (ANPC), or a flying capacitor multilevel circuit, etc. The specific topology can be determined according to the actual application scenario and is not limited here. Please refer to [further details omitted]. Figure 6 , Figure 6 This is a schematic diagram illustrating the working principle of the DC / AC conversion unit provided in this application. Figure 6 As shown, after the DC / AC conversion unit 201 is started, it can detect the target waveform signal of the DC bus in real time (such as the waveform signal of the voltage across the bus capacitor or the waveform signal of the current flowing through the bus inductor). When the detected target waveform signal matches a preset waveform (i.e., the waveform of the target waveform signal is exactly the same as the preset waveform), it starts operating and runs off-grid to achieve a black start for the energy storage system 1. The DC / AC conversion unit 201 stores the preset waveform. Optionally, the DC / AC conversion unit 201 can also actively start operating when the detected matching degree between the target waveform signal and the preset waveform is greater than or equal to a matching degree threshold to achieve a black start for the energy storage system 1. The specific method can be determined according to the actual application scenario and is not limited here. The matching degree threshold can be a user-set threshold or a default value configured for the energy storage system 1. Conversely, if the DC / AC conversion unit 201 detects that the waveform of the target waveform signal is not the preset waveform, it stops operating. Optionally, the DC / AC conversion unit 201 terminates its operation when it detects that the waveform of the target waveform signal matches the preset waveform less than the matching threshold.

[0038] Please see also Figure 7 , Figure 7 This is yet another structural schematic diagram of the energy storage system provided in this application. For example... Figure 7As shown in 7a, the DC bus 30 may include bus capacitors (such as capacitors C1 to Cn). These capacitors C1 to Cn can be connected in series and then in parallel across the output terminals of the DC / DC converter unit 102. For ease of description, the following explanation will use capacitors C1 to Cn as the bus capacitors; further details will not be repeated here. The DC / DC converter unit 102 can perform open-loop control on the reference voltages corresponding to capacitors C1 to Cn to control the on / off state of each switch in the DC / DC converter unit 102, thereby generating a target waveform signal (such as the waveform signal of the voltage across capacitors C1 to Cn) on capacitors C1 to Cn. The reference voltages corresponding to capacitors C1 to Cn can be understood as the total reference voltage when the series-connected capacitors C1 to Cn are treated as a whole. Optionally, the DC / DC converter unit 102 can also acquire the feedback voltages corresponding to capacitors C1 to Cn in real time, and perform closed-loop control on the reference voltages and feedback voltages corresponding to capacitors C1 to Cn based on the bus voltage loop, so as to control the conduction or cutoff of the above-mentioned switches, thereby generating waveform signals of the voltages across capacitors C1 to Cn. Here, the feedback voltages corresponding to capacitors C1 to Cn can be understood as the total output voltage when the series-connected capacitors C1 to Cn are treated as a whole. The DC / AC converter unit 201 can actively start working when it detects that the waveform of the waveform signal of the voltages across capacitors C1 to Cn is a preset waveform, so as to realize the black start of the energy storage system 1.

[0039] Optionally, in some feasible implementations, such as Figure 7As shown in 7b, the DC bus 30 may include bus inductors (such as inductors L1 to Ln), which can be connected in series with each other and then connected in series with the DC / DC converter unit 102. In other words, the DC bus 30 can be composed of inductors L1 to Ln connected in series. For ease of description, the following explanation will take inductors L1 to Ln as an example, and will not be repeated below. The DC / DC converter unit 102 can perform open-loop control on the reference voltages corresponding to inductors L1 to Ln to control the on or off of each switch in the DC / DC converter unit 102, thereby generating target waveform signals (such as waveform signals of the current flowing through inductors L1 to Ln) on inductors L1 to Ln. The reference voltages corresponding to inductors L1 to Ln can be understood as the total reference voltage when the series-connected inductors L1 to Ln are treated as a whole. Optionally, the DC / DC converter unit 102 can acquire the feedback voltages corresponding to inductors L1 to Ln in real time, and perform closed-loop control on the reference voltages and feedback voltages corresponding to inductors L1 to Ln based on the bus voltage loop to control the conduction or cutoff of the aforementioned switches, thereby generating the waveform signals of the aforementioned currents on inductors L1 to Ln. Here, the feedback voltages corresponding to inductors L1 to Ln can be understood as the total output voltage when the series-connected inductors L1 to Ln are treated as a whole. The DC / AC converter unit 201 can detect the waveform signals of the currents flowing through inductors L1 to Ln in real time, and actively start working when the waveform of the current signal is a preset waveform, so as to realize the black start of the energy storage system 1.

[0040] In some feasible implementations, the waveform of the target waveform signal (i.e., the preset waveform) can be any waveform other than the waveform signal generated on the DC bus 30 during normal startup of the energy storage system 1 (such as a straight line). The energy storage system 1 may also include an energy management system. During normal startup of the energy storage system 1, the energy storage module 10, the energy conversion module 20, and the energy management system can work together. The energy management system can issue a startup command to the DC / AC conversion unit 201 to start the DC / AC conversion unit 201. At this time, the waveform signal generated on the DC bus 30 can be a straight line with a constant voltage or constant current, or a straight line with small spikes. For example, the waveform of the target waveform signal can be a square wave, a stepped wave, a sine wave, a sawtooth wave, a rectangular wave, a triangular wave, a trapezoidal wave, or other waveforms, which can be determined according to the actual application scenario and are not limited here.

[0041] Please see also Figure 8 , Figure 8 This is a waveform diagram of the target waveform signal provided in this application. For example... Figure 8As shown in 8a, the target waveform signal can be a square wave. Assuming the preset waveform stored in the DC / AC conversion unit 201 is a square wave, the DC / AC conversion unit 201 starts working when it detects that the target waveform signal on the DC bus 30 is a square wave, thus achieving a black start for the energy storage system 1. Figure 8 As shown in 8b, the target waveform signal can be a stepped wave. Assuming the preset waveform stored in the DC / AC conversion unit 201 is a stepped wave, the DC / AC conversion unit 201 starts operating when it detects that the target waveform signal on the DC bus 30 is a stepped wave, thus achieving a black start for the energy storage system 1. Figure 8 As shown in 8c, the target waveform signal can be a sine wave. Assuming the preset waveform stored in the DC / AC conversion unit 201 is a sine wave, the DC / AC conversion unit 201 starts working when it detects that the target waveform signal on the DC bus 30 is a sine wave, thereby achieving a black start for the energy storage system 1. It can be understood that a black start for the energy storage system 1 refers to restarting the energy storage system 1 without relying on the main power grid or other energy storage systems after it has stopped operating due to an external or internal fault and entered a completely dark state. This is achieved by activating the black start unit 104 within the energy storage system 1, which has black start capability. This ensures the power supply to critical loads and the continuous and stable operation of the energy storage system 1, while also shortening the recovery time of the energy storage system 1 and reducing losses caused by power outages.

[0042] In some feasible implementations, after the energy storage system 1 is restarted based on a black start, the output of the DC / AC conversion unit 201 can also be connected to an AC power grid or an AC load. When the output of the DC / AC conversion unit 201 is connected to an AC power grid or an AC load, it can convert the DC power output by the energy storage module 10 into AC power to supply power to the AC power grid or AC load. Please refer to [further details omitted]. Figure 9 , Figure 9 This is a power supply diagram of the energy storage system provided in this application. For example... Figure 9As shown, after the energy storage system 1 enters a completely dark state, the black-start unit 104 with black-start capability within the energy storage system 1 can be activated, thereby starting the energy storage units 101 and battery control unit 103 without black-start capability. This further activates the DC / DC converter unit 102 and DC / AC converter unit 201, gradually expanding the recovery range of the energy storage system 1 and ultimately restarting it. After the energy storage system 1 restarts, the energy storage unit 101 can provide a DC input voltage to the DC / DC converter unit 102. The DC / DC converter unit 102 can then perform power conversion on the DC input voltage, outputting DC power to the DC / AC converter unit 201. At this time, the DC / AC converter unit 201 can perform power conversion on the DC power input to the DC / DC converter unit 102, outputting AC power to the AC grid or AC load to supply power to the AC grid or AC load. Optionally, as... Figure 9 As shown above Figure 3 The energy storage system 1 shown may also include an energy management system 40. When the energy storage system 1 is started normally, the energy management system 40 can send a start command to the DC / AC conversion unit 201. The DC / AC conversion unit 201 can receive the start command from the energy management system 40 and start working, converting the DC power output by the energy storage module 10 into AC power to supply power to the AC grid or AC load.

[0043] In this application, even when the power-on command from the energy management system cannot be received, the energy conversion module can also actively start working when the target waveform signal of the DC bus is detected, thereby realizing the black start of the energy storage system, which is lower in cost and more applicable.

[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An energy storage system, characterized in that, The energy storage system includes an energy storage module and an energy conversion module. The energy storage module includes an energy storage unit and a DC / DC converter unit. The energy storage unit is connected in parallel with the input terminal of the DC / DC converter unit, and the output terminal of the DC / DC converter unit is connected to the energy conversion module through a DC bus. The energy storage unit is used to provide DC input voltage to the DC / DC converter unit; The DC / DC converter unit is used to generate a target waveform signal on the DC bus when a black start signal is received; The energy conversion module is used to detect the target waveform signal of the DC bus and start working based on the target waveform signal.

2. The energy storage system according to claim 1, characterized in that, The energy storage module also includes a battery control unit; The battery control unit is used to send a black start signal to the DC / DC converter unit when a black start command is detected; The DC / DC converter unit is used to receive the black start signal from the battery control unit and generate the target waveform signal on the DC bus.

3. The energy storage system according to claim 2, characterized in that, The energy storage module also includes a black start unit, which is connected to the energy storage unit; The black start unit is used to generate black start instructions; The energy storage unit is used to send the black start command back to the battery control unit when the black start command is detected.

4. The energy storage system according to claim 2 or 3, characterized in that, The DC / DC converter unit is used to perform open-loop control of the reference voltage of the DC bus to generate the target waveform signal on the DC bus.

5. The energy storage system according to claim 2 or 3, characterized in that, The DC / DC conversion unit includes a bus voltage loop; The DC / DC converter unit is also used to acquire the feedback voltage of the DC bus, and to perform closed-loop control on the reference voltage of the DC bus and the feedback voltage based on the bus voltage loop to generate a target waveform signal on the DC bus.

6. The energy storage system according to any one of claims 2-5, characterized in that, The DC bus includes a bus capacitor, which is connected in parallel with the DC / DC conversion unit.

7. The energy storage system according to claim 6, characterized in that, The target waveform signal is the waveform signal of the voltage across the two ends of the bus capacitor.

8. The energy storage system according to any one of claims 2-5, characterized in that, The DC bus includes a bus inductor, which is connected in series with the DC / DC conversion unit.

9. The energy storage system according to claim 8, characterized in that, The target waveform signal is the waveform signal of the current flowing through the bus inductor.

10. The energy storage system according to any one of claims 1-9, characterized in that, The energy conversion module is a DC / AC conversion unit, and the output terminal of the DC / AC conversion unit is used to connect to an AC power grid or an AC load. The DC / AC conversion unit is also used to convert the DC power output by the energy storage module into AC power when the output terminal is connected to the AC power grid or the AC load, so as to supply power to the AC power grid or the AC load.

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