A high-voltage direct-hanging energy storage system based on DC-DC and a control method thereof

Abstract

The application provides a high-voltage direct-hanging energy storage system based on DC-DC and a control method thereof, and belongs to the technical field of high-voltage direct-hanging energy storage systems. The system comprises a plurality of battery packs and a plurality of power modules. The battery packs and the power modules are connected in a cascaded form to a medium-high voltage power grid. An isolation topology module is connected in parallel between the battery packs and the power modules. The isolation topology module comprises a common-mode inductor and a current stabilizing unit. A first end of the common-mode inductor is connected to a battery pack, a second end of the common-mode inductor is connected to a first end of the current stabilizing unit, and a second end of the current stabilizing unit is connected to a power module. Through the isolation topology module, common-mode interference is effectively suppressed, and secondary pulsating current can be effectively absorbed. Through an LC passive filter composed of the common-mode inductor and a direct-current voltage stabilizing capacitor C1, common-mode interference and secondary pulsating current problems caused by cable parasitic parameters are more effectively suppressed.

Description

Technical Field

[0001] This invention belongs to the technical field of high-voltage direct-connected energy storage systems, and particularly relates to a high-voltage direct-connected energy storage system based on DC-DC and its control method. Background Technology

[0002] As the proportion of new energy sources connected to the grid increases, the power fluctuation problem caused by photovoltaic and wind power is becoming increasingly apparent. Configuring a series of energy storage systems can effectively solve this power fluctuation problem.

[0003] Currently, lithium-ion battery technology, primarily based on lithium iron phosphate batteries, is relatively mature, offering advantages such as high safety and low cost. Energy storage power stations already utilize lithium-ion battery packs. However, most energy storage power stations still employ centralized or string parallel connection methods, connecting to the medium- and high-voltage power grid via step-up transformers. This type of grid connection method suffers from problems such as high power loss and high cost.

[0004] To reduce the conversion steps between DC batteries and the AC grid, improve the overall efficiency of the energy storage power station, and simplify the conversion process, high-voltage direct-connected energy storage systems are typically used.

[0005] However, in existing high-voltage direct-connected energy storage systems, there is a common-mode interference problem between the battery pack and the power module. The secondary pulsating current on the battery pack side affects the normal operation of high-voltage direct-connected energy storage. Therefore, how to solve the common-mode interference, secondary pulsating current and high-voltage ride-through of the battery pack has become a technical problem to be solved. Summary of the Invention

[0006] This invention provides a DC-DC-based high-voltage direct-connected energy storage system and its control method, which at least solves the problem of common-mode interference between the battery pack and the power module in the prior art.

[0007] In a first aspect, embodiments of this application provide a DC-DC-based high-voltage direct-connected energy storage system. The system includes several battery packs and several power modules. The battery packs and the power modules are connected to the medium- and high-voltage power grid in a cascaded manner. An isolation topology module is connected in parallel between the battery packs and the power modules.

[0008] The isolation topology module includes a common-mode inductor. and current stabilization unit;

[0009] The common mode inductor The first end is connected to the battery pack via a cable, and the common mode inductor The second end is connected to the first end of the current stabilizing unit, and the second end of the current stabilizing unit is connected to the power module.

[0010] Furthermore, the current stabilizing unit includes a DC-side voltage stabilizing capacitor C1, an inductor L3, a cascaded DC-DC converter G11, a cascaded DC-DC converter G12, a cascaded DC-DC converter G13, a cascaded DC-DC converter G14, and a pulsation buffer capacitor C2.

[0011] The first end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G11 and the collector of the cascaded DC-DC converter G13.

[0012] The collector of the cascaded DC-DC converter G11 is connected to the first terminal of the DC-side voltage regulator capacitor C1, and then connected to a common-mode inductor. The second end;

[0013] The emitter of the cascaded DC-DC converter G13 is connected to the second terminal of the DC-side voltage regulator capacitor C1, and then connected to a common-mode inductor. The second end;

[0014] The second end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G12 and the collector of the cascaded DC-DC converter G14.

[0015] The collector of the cascaded DC-DC converter G12 and the first terminal of the pulsating buffer capacitor C2 are connected to the upper output terminal of the power module.

[0016] The emitter of the cascaded DC-DC converter G14 and the second terminal of the pulsating buffer capacitor C2 are connected to the lower output terminal of the power module.

[0017] Common mode inductor Together with the DC-side voltage regulator capacitor C1, they form an LC passive filter.

[0018] Furthermore, considering the common-mode current interference as a step response to a voltage pulse, the common-mode interference current corresponding to one power module is:

[0019]

[0020] in:

[0021] In the formula, For common-mode interference current, The voltage of a battery pack. This refers to the number of battery packs corresponding to one power module. For the parasitic capacitance of the cable, For the parasitic inductance of the cable, Parasitic resistance of the line, For parasitic resistance to ground, This refers to the number of power modules connected in parallel in one phase of a three-phase alternating current system. and To and Correlation coefficient For a certain power module connected in parallel;

[0022] Parasitic capacitance of cables Compared to the parasitic inductance of cables Line parasitic resistance Parasitic resistance to ground The common-mode interference current is relatively small and therefore negligible. The peak value is:

[0023]

[0024] In the formula, Common-mode interference current The peak value;

[0025] Add common mode inductor common-mode interference current The peak value is:

[0026]

[0027] In the formula, To add a common mode inductor common-mode interference current The peak value.

[0028] Furthermore, common mode inductor Together with the DC-side voltage regulator capacitor C1, they form an LC passive filter to suppress the secondary pulsating current;

[0029] By using the absence of common-mode inductor The energy storage system is subjected to Fourier transform and carrier phase-shift modulation strategy to calculate the secondary pulsating current:

[0030]

[0031] In the formula, It is a secondary pulsating current. This is the DC-side current component. This refers to the battery's internal resistance.

[0032] Through common mode inductor Together with the DC-side voltage regulator capacitor C1, they form an LC passive filter to suppress the secondary pulsating current. The secondary pulsating current after passing through the LC passive filter is:

[0033]

[0034] At this point, the system becomes a second-order oscillating system, which suppresses the secondary pulsating current to a certain extent in a short period of time.

[0035] Furthermore, the operating modes of the current stabilization unit are: boost mode and buck mode;

[0036] Battery power generation: In boost mode, only cascaded DC-DC converters G12 and G14 are working; in buck mode, only cascaded DC-DC converters G11 and G13 are working.

[0037] Battery charging: In boost mode, only cascaded DC-DC converters G11 and G13 are working; in buck mode, only cascaded DC-DC converters G12 and G14 are working.

[0038] Furthermore, in boost mode, cascaded DC-DC converter G11 is turned on. At this time, cascaded DC-DC converters G12 and G14 are controlled by modulation signals to increase the voltage output to the power module. The expression for the voltage output to the power module is:

[0039]

[0040] In the formula, , , Input side voltage, The voltage output to the power module, For the inductor current, according to the volt-second balance theory, we get:

[0041] .

[0042] Furthermore, the system also includes: an AC disconnect switch S1, a soft-start switch S2, a reactor L1, and a soft-start resistor R1;

[0043] The soft-start switch S2 is connected in series with the soft-start resistor R1;

[0044] The first terminal of the soft start switch S2 is connected to the first terminal of the AC disconnect switch S1 to the medium-high voltage power grid.

[0045] The second terminal of the soft-start switch S2 is connected to the first terminal of the soft-start resistor R1;

[0046] The second terminal of the soft-start resistor R1 is connected to the first terminal of the reactor L1 via the second terminal of the AC disconnect switch S1.

[0047] The second end of the reactor L1 is connected to the upper output end of the power module.

[0048] Secondly, embodiments of this application also provide a control method for a DC-DC-based high-voltage direct-connected energy storage system as described in the above aspects, the method comprising:

[0049] Step S1: Estimate the SOC status of the battery pack. If the SOC status of the battery pack is less than or equal to 20% of the battery capacity, proceed to step S2; otherwise, proceed to step S3.

[0050] Step S2: Do not discharge, issue a warning and coordinate with other battery packs to discharge, and return to execute step S1;

[0051] Step S3: Based on the fluctuations in the mains voltage, set the output voltage of the DC-DC converter and select the operating mode;

[0052] Step S4: Based on the selected operating mode, increase or decrease the voltage output to the power module;

[0053] Step S5: Calculate whether to increase or decrease the output voltage to the power module;

[0054] Step S6: Determine whether the voltage difference between the output voltage to the power module and the mains voltage is less than 5% of the mains voltage. If it is less, end the process; otherwise, return to step S3.

[0055] Thirdly, an electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the steps of the control methods described in the preceding aspects.

[0056] Fourthly, a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the control methods described in the preceding aspects.

[0057] As can be seen from the above technical solutions, the present invention has the following advantages:

[0058] This application provides a DC-DC-based high-voltage direct-connected energy storage system and its control method. Through an isolated topology module, common-mode interference is effectively suppressed, and secondary pulsating current is effectively absorbed. This is achieved through a common-mode inductor. This effectively suppresses common-mode interference caused by cable parasitic parameters.

[0059] Common mode inductor Together with the DC-side voltage regulator capacitor C1, they form an LC passive filter. Through the isolation topology module composed of the LC passive filter and the DC-DC converter, the secondary pulsating current is suppressed, thus solving the problem of secondary pulsating current on the battery pack side.

[0060] The DC-DC converter also achieves higher voltage gain through cascaded topology, increases the voltage amplitude of the buffer capacitor to suppress secondary pulsating current, and enables the battery pack to raise or lower the output voltage to the power module according to actual operating conditions, completing the high-voltage ride-through condition when the grid voltage fluctuates. This improves the high-voltage ride-through capability of the energy storage system and ensures the stable operation of high-voltage direct-connected energy storage.

[0061] By directly connecting multiple battery packs and power modules to the medium- and high-voltage power grid in a cascaded manner, the step-up transformer is eliminated; this grid connection method reduces power loss and cost. Attached Figure Description

[0062] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 This is a topology diagram of the DC-DC-based high-voltage direct-connected energy storage system of the present invention.

[0064] Figure 2 This is a schematic diagram of the isolation module topology of the DC-DC-based high-voltage direct-connected energy storage system of the present invention.

[0065] Figure 3 This is a diagram showing the boost mode operation of the cascaded DC-DC converter in the DC-DC-based high-voltage direct-connected energy storage system of this invention.

[0066] Figure 4 This is a state diagram of the step-down operating mode of the cascaded DC-DC converter in the DC-DC-based high-voltage direct-connected energy storage system of the present invention.

[0067] Figure 5 This is a simulation diagram of the secondary pulsating current of the DC-DC-based high-voltage direct-connected energy storage system of the present invention.

[0068] Figure 6 This is a modulation diagram of the cascaded DC-DC converter of the DC-DC-based high-voltage direct-connected energy storage system of the present invention.

[0069] Figure 7 This is a flowchart of the control method for the DC-DC-based high-voltage direct-connected energy storage system of the present invention.

[0070] Figure 8 This is a simulation diagram of the output voltage of the DC-DC converter in the DC-DC-based high-voltage direct-connected energy storage system of this invention. Detailed Implementation

[0071] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this patent, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this patent.

[0072] This invention provides a DC-DC-based high-voltage direct-connected energy storage system and energy storage unit control strategy, which solves the common-mode interference problem of existing energy storage systems. By using a two-stage pulsating current suppression circuit composed of LC filter and DC-DC converter, it solves the problem of secondary pulsating current on the battery pack side, realizes the voltage increase or decrease of the energy storage battery pack output to the power module according to the actual operating conditions, improves the high-voltage ride-through capability of the energy storage system, and ensures the stable operation of high-voltage direct-connected energy storage.

[0073] The technical solutions proposed in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0074] Combination Figure 1 and Figure 2 This application provides a DC-DC-based high-voltage direct-connected energy storage system. The system includes several battery packs and several power modules. The battery packs and power modules are connected to the medium- and high-voltage power grid in a cascaded manner. Energy storage systems are developing towards high voltage, large capacity, and clustered operation. This invention directly connects multiple battery packs and power modules to the medium- and high-voltage power grid in a cascaded manner, eliminating the need for a step-up transformer. This grid connection method reduces power loss and cost.

[0075] An isolation topology module is connected in parallel between the battery pack and the power module;

[0076] The isolation topology module includes a common-mode inductor. and current stabilization unit;

[0077] The common mode inductor The first end is connected to the battery pack, and the common mode inductor The second end is connected to the first end of the current stabilizing unit, and the second end of the current stabilizing unit is connected to the power module.

[0078] For safety and high voltage rating considerations, battery packs in high-voltage direct-connected energy storage systems are typically placed in remote locations far from the power modules. Their cables are long and thick, leading to significant common-mode interference caused by cable parasitic parameters. Furthermore, secondary pulsating current exists between the battery pack and the power module, which can damage the battery pack and cause safety accidents over time. This invention effectively suppresses common-mode interference and absorbs secondary pulsating current through an isolated topology module, utilizing a common-mode inductor. This effectively suppresses common-mode interference caused by cable parasitic parameters.

[0079] In an exemplary embodiment, the current stabilizing unit includes a DC-side voltage stabilizing capacitor C1, an inductor L3, a cascaded DC-DC converter G11, a cascaded DC-DC converter G12, a cascaded DC-DC converter G13, a cascaded DC-DC converter G14, and a pulsating buffer capacitor C2.

[0080] The first end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G11 and the collector of the cascaded DC-DC converter G13.

[0081] The collector of the cascaded DC-DC converter G11 is connected to the first terminal of the DC-side voltage regulator capacitor C1, and then connected to a common-mode inductor. The second end;

[0082] The emitter of the cascaded DC-DC converter G13 is connected to the second terminal of the DC-side voltage regulator capacitor C1, and then connected to a common-mode inductor. The second end;

[0083] The second end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G12 and the collector of the cascaded DC-DC converter G14.

[0084] The collector of the cascaded DC-DC converter G12 and the first terminal of the pulsating buffer capacitor C2 are connected to the upper output terminal of the power module.

[0085] The emitter of the cascaded DC-DC converter G14 and the second terminal of the pulsating buffer capacitor C2 are connected to the lower output terminal of the power module.

[0086] Common mode inductor Together with the DC-side voltage regulator capacitor C1, they form an LC passive filter.

[0087] like Figure 2The secondary pulsating current is effectively suppressed by using a cascaded DC-DC converter. By setting up a cascaded DC-DC converter, the pulsating buffer capacitor C2 is not directly connected in parallel with the battery pack. At this time, the voltage amplitude of the pulsating buffer capacitor is increased by using a cascaded DC-DC converter to suppress the secondary pulsating current. Moreover, the cascaded DC-DC converter has a higher voltage gain compared with other converters, which meets the design requirements of high-voltage direct-connected energy storage systems.

[0088] Common mode inductor Together with the DC-side voltage regulator capacitor C1, they form an LC passive filter. Through the isolation topology module composed of the LC passive filter and the DC-DC converter, the secondary pulsating current is suppressed, thus solving the problem of secondary pulsating current on the battery pack side.

[0089] The DC-DC converter also achieves higher voltage gain through cascaded topology, increases the voltage amplitude of the buffer capacitor to suppress secondary pulsating current, and enables the battery pack to raise or lower the output voltage to the power module according to actual operating conditions. Through effective logic control, it completes the high-voltage ride-through condition when the grid voltage fluctuates, improves the high-voltage ride-through capability of the energy storage system, and ensures the stable operation of high-voltage direct-connected energy storage.

[0090] As an example, consider the common-mode current interference as a step response to a voltage pulse, where the common-mode interference current corresponding to a power module is:

[0091]

[0092] in:

[0093] In the formula, For common-mode interference current, The voltage of a battery pack. This refers to the number of battery packs corresponding to one power module. For the parasitic capacitance of the cable, For the parasitic inductance of the cable, Parasitic resistance of the line, For parasitic resistance to ground, This refers to the number of power modules connected in parallel in one phase of a three-phase alternating current system. and To and Correlation coefficient For a certain power module connected in parallel;

[0094] Parasitic capacitance of cables Compared to the parasitic inductance of cables Line parasitic resistance Parasitic resistance to ground The common-mode interference current is relatively small and therefore negligible. The peak value is:

[0095]

[0096] In the formula, Common-mode interference current The peak value;

[0097] At this time, the peak value of the common-mode interference current generated by multiple parallel power modules in one phase increases the current stress of the power module due to its long duration, thus increasing losses and heat generation.

[0098] like Figure 2 The circuit diagram of the isolated topology module is given.

[0099] Understandable, Figure 2 In C1 is a common-mode inductor, G11, G12, G13 and G14 are cascaded DC-DC converter IGBTs, and C2 is a pulsation buffer capacitor.

[0100] Furthermore, common mode inductors It has a suppressive effect on common-mode interference current. As can be seen from the above derivation of the peak value of the common-mode interference current, adding a common-mode inductor... common-mode interference current The peak value is:

[0101]

[0102] In the formula, To add a common mode inductor common-mode interference current The peak value;

[0103] Among them, common mode inductors Much larger than the parasitic inductance of the cable Parasitic capacitance of cables ,at this time much smaller .

[0104] It should be noted that the parasitic inductance of the cable 60μH common mode inductance Between 2mH and 10mH, therefore, a common-mode inductance is added. The denominator increases significantly after adding a common-mode inductor. common-mode interference current peak The peak value decreased significantly, that is much smaller .

[0105] In one embodiment, the common-mode inductor Together with the DC-side voltage regulator capacitor C1, they form an LC passive filter to suppress the secondary pulsating current;

[0106] By using the absence of common-mode inductor The energy storage system is subjected to Fourier transform and carrier phase-shift modulation strategy to calculate the secondary pulsating current:

[0107]

[0108] In the formula, It is a secondary pulsating current. This is the DC-side current component. This refers to the battery's internal resistance.

[0109] Through common mode inductor Together with the DC-side voltage regulator capacitor C1, they form an LC passive filter that can suppress secondary pulsating current. The secondary pulsating current after passing through the LC passive filter is:

[0110]

[0111] At this point, the system becomes a second-order oscillating system, which suppresses the secondary pulsating current to a certain extent in a short period of time.

[0112] According to embodiments of this application, in conjunction with Figure 3 and Figure 4 The current stabilizing unit operates in two modes: boost mode and buck mode.

[0113] Battery power generation: In boost mode, only cascaded DC-DC converters G12 and G14 are working; in buck mode, only cascaded DC-DC converters G11 and G13 are working.

[0114] Battery charging: In boost mode, only cascaded DC-DC converters G11 and G13 are working; in buck mode, only cascaded DC-DC converters G12 and G14 are working.

[0115] Figure 6 This is a modulation diagram of a cascaded DC-DC converter. Figure 6 middle, For battery-powered boost mode carrier signal, For battery power generation buck mode carrier signal, It is the modulated wave control signal.

[0116] Understandably, the first step is to determine the battery pack's State of Charge (SOC). Based on the SOC, the PWM modulation is adjusted to increase the voltage and shorten the battery pack's charging and discharging time. Taking the battery pack's power generation mode as an example, when operating in boost mode, the modulation wave control signal... Greater than the carrier signal of the battery power generation buck mode At this time, cascaded DC-DC converter G11 is turned on, and cascaded DC-DC converters G12 and G14 are turned on alternately to achieve voltage boost.

[0117] According to another embodiment of the present invention, in boost mode, cascaded DC-DC converter G11 is turned on. At this time, cascaded DC-DC converters G12 and G14 are controlled by modulation signals to increase the voltage output to the power module. The expression for the voltage output to the power module is:

[0118]

[0119] In the formula, , , Input side voltage, The voltage output to the power module, For the inductor current, according to the volt-second balance theory, we get:

[0120] .

[0121] It should be noted that the system also includes: AC disconnect switch S1, soft start switch S2, reactor L1, and soft start resistor R1;

[0122] The soft-start switch S2 is connected in series with the soft-start resistor R1;

[0123] The first terminal of the soft start switch S2 is connected to the first terminal of the AC disconnect switch S1 to the medium-high voltage power grid.

[0124] The second terminal of the soft-start switch S2 is connected to the first terminal of the soft-start resistor R1;

[0125] The second terminal of the soft-start resistor R1 is connected to the first terminal of the reactor L1 via the second terminal of the AC disconnect switch S1.

[0126] The second end of the reactor L1 is connected to the upper output end of the power module.

[0127] Combination Figure 1 The AC disconnect switch S1 is used to disconnect and connect the energy storage system to the medium- and high-voltage power grid. The soft-start switch S2 and soft-start resistor R1 are used to reduce the inrush current during grid connection. The reactor L1 is used to filter the output current of the energy storage system and suppress current surges.

[0128] Combination Figure 6The present invention also provides a control method for a DC-DC-based high-voltage direct-connected energy storage system as described in the above embodiments, the method comprising:

[0129] Step S1: Estimate the SOC status of the battery pack. If the SOC status of the battery pack is less than or equal to 20% of the battery capacity, proceed to step S2; otherwise, proceed to step S3.

[0130] Step S2: Do not discharge, issue a warning and coordinate with other battery packs to discharge, and return to execute step S1;

[0131] Step S3: Based on the fluctuations in the mains voltage, set the output voltage of the DC-DC converter and select the operating mode;

[0132] Step S4: Based on the selected operating mode, increase or decrease the voltage output to the power module;

[0133] Step S5: Calculate whether to increase or decrease the output voltage to the power module;

[0134] Step S6: Determine whether the voltage difference between the output voltage to the power module and the mains voltage is less than 5% of the mains voltage. If it is less, end the process; otherwise, return to step S3.

[0135] Figure 8 The simulation diagram of the output voltage of the DC-DC converter is shown below. Figure 8 When the battery begins to discharge, the voltage rises sharply due to the influence of the dual closed-loop control PI regulator. However, the presence of the soft-start resistor will not damage the circuit. As the voltage gradually stabilizes, the grid voltage begins to rise slightly at 0.8s. The DC-DC converter gradually increases the grid voltage to 5%, which is 1 / N1 times the magnitude of the grid voltage.

[0136] DC-DC converters can not only suppress secondary pulsating current, but also address the high-voltage ride-through condition often encountered by high-voltage direct-connected energy storage systems during grid voltage fluctuations. This invention achieves high and low voltage ride-through by increasing or decreasing the DC-side voltage of the power module through the buck-boost mode of cascaded DC-DC converters.

[0137] It should be noted that, based on the power setpoint and the three-phase voltage and current, the voltage sampled after dq transformation is used to obtain the reference current value. The reference current value and the current sampled after dq transformation are then subjected to PI control and Park inverse transformation to obtain the reference three-phase voltage value.

[0138] The reference three-phase voltage values ​​and the zero-sequence voltage output from the power module converter are injected into the PWM modulation to perform inter-phase power compensation and realize the converter control of high-voltage direct-connected energy storage.

[0139] The control method for a DC-DC-based high-voltage direct-connected energy storage system provided in this application can be applied to electronic devices. Those skilled in the art will understand that the electronic device structure involved in the embodiments of this invention does not constitute a limitation on the electronic device. The electronic device may include more or fewer components than illustrated, or combine certain components, or have different component arrangements. In the embodiments of this invention, the electronic device includes, but is not limited to, laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments of this application described and / or claimed herein.

[0140] Electronic devices may include processors, external memory interfaces, internal memory, universal serial bus (USB) interfaces, charging management modules, power management modules, batteries, wireless communication modules, audio modules, speakers, microphones, sensor modules, buttons, cameras, displays, and SIM card interfaces, etc.

[0141] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the electronic device. In other embodiments of this application, the electronic device may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0142] A processor may include one or more processing units, such as: a central processing unit (CPU), an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, memory, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural network processing unit (NPU). Different processing units may be independent devices or integrated into one or more processors.

[0143] The processor can serve as the nerve center and command center of an electronic device. The controller can generate operation control signals based on the instruction opcode and timing signals to control the fetching and execution of instructions.

[0144] The processor may also include memory for storing instructions and data. In some embodiments, the memory in the processor is a cache memory. This memory can store instructions or data that the processor has just used or that are used repeatedly. If the processor needs to use the instruction or data again, it can retrieve it directly from this memory. This avoids repeated accesses, reduces processor latency, and thus improves system efficiency.

[0145] An external storage interface (ESI) can be used to connect external memory cards, such as microSD cards, to expand the storage capacity of electronic devices. The external memory card communicates with the processor through the ESI to perform data storage functions, such as saving music and video files on the external memory card.

[0146] Internal memory can be used to store computer executable program code, which includes instructions. The processor executes various functional applications and data processing of electronic devices by running the instructions stored in internal memory. Internal memory can include a program storage area and a data storage area. Internal memory can include high-speed random access memory, and can also include non-volatile memory, such as at least one disk storage device, flash memory device, universal flash storage (UFS), etc.

[0147] Wireless communication functionality in electronic devices can be achieved through antennas, wireless communication modules, modem processors, and baseband processors.

[0148] Wireless communication modules can provide solutions for wireless communication applications in electronic devices, including wireless local area networks (WLANs) (such as wireless fidelity (Wi-Fi) networks), Bluetooth (BT), global navigation satellite system (GNSS), frequency modulation (FM), near field communication (NFC), and infrared (IR) technologies.

[0149] Electronic devices can implement audio functions through audio modules, speakers, receivers, microphones, headphone jacks, and application processors.

[0150] Electronic devices can achieve shooting functions through ISPs, cameras, video codecs, GPUs, displays, and application processors.

[0151] Electronic devices can achieve display functions through GPUs, displays, and application processors.

[0152] A GPU is a microprocessor for image processing, connected to the display screen and application processor. GPUs are used to perform mathematical and geometric calculations for graphics rendering. A processor may include one or more GPUs, which execute program instructions to generate or modify display information.

[0153] A display screen is used to display images, videos, etc. A display screen includes a display panel.

[0154] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0155] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of devices, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0156] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, apparatuses, or units, or they may be electrical, mechanical, or other forms of connection.

[0157] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of the invention.

[0158] The aforementioned electronic device implements the control method of the DC-DC-based high-voltage direct-connected energy storage system of this application. The method includes: Step S1: Estimating the SOC status of the battery pack. If the SOC status of the battery pack is less than or equal to 20% of the charge, proceed to Step S2; otherwise, proceed to Step S3. Step S2: Do not discharge, issue a warning and coordinate other battery packs to discharge, and return to Step S1. Step S3: Set the output voltage of the DC-DC converter and select the operating mode according to the fluctuation of the grid voltage. Step S4: Increase or decrease the voltage output to the power module based on the selected operating mode. Step S5: Calculate whether to increase or decrease the voltage output to the power module. Step S6: Determine whether the voltage difference between the voltage output to the power module and the grid voltage is less than 5% of the grid voltage. If it is less, the process ends; otherwise, return to Step S3. By isolating the topology module, common-mode interference is effectively suppressed and secondary pulsating current can be effectively absorbed. Through the common-mode inductor... This effectively suppresses common-mode interference caused by cable parasitic parameters.

[0159] The storage medium provided in this application stores a program product capable of implementing a control method for a DC-DC-based high-voltage direct-connected energy storage system.

[0160] The control method for a DC-DC-based high-voltage direct-connected energy storage system includes: estimating the state of charge (SOC) of the battery pack; when the SOC of the battery pack is less than or equal to 20% of its charge, no discharge is performed, an early warning is issued, and other battery packs are coordinated to discharge; otherwise, based on the fluctuation of the grid voltage, the output voltage of the DC-DC converter is set, and the operating mode is selected; based on the selected operating mode, the voltage output to the power module is increased or decreased; the increase or decrease of the voltage output to the power module is calculated; and it is determined whether the voltage difference between the voltage output to the power module and the grid voltage is less than 5% of the grid voltage. If it is less, the process ends.

[0161] DC-DC converters can not only suppress secondary pulsating current, but also address the high-voltage ride-through condition often encountered by high-voltage direct-connected energy storage systems during grid voltage fluctuations. This invention achieves high and low voltage ride-through by increasing or decreasing the DC-side voltage of the power module through the buck-boost mode of cascaded DC-DC converters.

[0162] In some possible implementations, the control method for a DC-DC-based high-voltage direct-connected energy storage system disclosed herein can be implemented as a program product comprising program code that, when the program product is run on a terminal device, causes the terminal device to perform the steps described in the "Exemplary Methods" section of this specification according to various exemplary embodiments of this disclosure.

[0163] The storage medium disclosed herein may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0164] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0165] For those skilled in the art, designing different forms of control circuits according to the teachings of this invention does not require creative effort. Changes, modifications, substitutions, and variations made to the embodiments without departing from the principles and spirit of this invention still fall within the scope of protection of this invention.

Claims

1. A DC-DC based high voltage direct plug-in energy storage system, the system comprising a plurality of battery packs and a plurality of power modules, the battery packs and the power modules being connected in cascade to a medium-high voltage grid, characterized in that, The isolation topology module is connected in parallel between the battery pack and the power module; The isolation topology module includes a common mode inductor and a current stabilizing unit; The common mode inductor The first end of the common mode inductor The second end of the common mode inductor connects the first end of the current stabilization unit, and the second end of the current stabilization unit connects the power module. The steady flow unit comprises a direct current side voltage stabilizing capacitor C1, an inductor L3, a cascaded DC-DC converter G11, a cascaded DC-DC converter G12, a cascaded DC-DC converter G13, a cascaded DC-DC converter G14 and a pulsation buffer capacitor C2; The first end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G11 and the collector of the cascaded DC-DC converter G13; The collector of the cascade DC-DC converter G11 is connected to the first end of the DC side voltage stabilizing capacitor C1, and then connected to the second end of the common mode inductor ​ The second end of the common mode inductor is connected to the emitter of the cascade DC-DC converter G13 and the second end of the DC side voltage stabilizing capacitor C1 ; The second end of the inductor L3 is connected to the emitter of the cascaded DC-DC converter G12 and the collector of the cascaded DC-DC converter G14; The collector of the cascaded DC-DC converter G12 and the first end of the pulsation buffer capacitor C2 are connected to the upper output end of the power module; The emitter of the cascaded DC-DC converter G14 and the second end of the pulsation buffer capacitor C2 are connected to the lower output end of the power module; Common mode inductance And the LC passive filter is composed of the direct current side voltage stabilizing capacitor C1; The common-mode current interference is regarded as a step response of a voltage pulse, wherein the common-mode interference current corresponding to one power module is: wherein: wherein, is the common mode interference current, is the voltage of one battery pack, is the number of battery packs corresponding to one power module, is the parasitic capacitance of the cable, is the parasitic inductance of the cable, is the line parasitic resistance, is the ground parasitic resistance, is the number of power modules in parallel for one phase of the three-phase AC power, and is the coefficient associated with , is a certain parallel power module; Parasitic capacitance of a cable Compared to the parasitic inductance of a cable Line parasitic resistance Parasitic resistance to ground is small and can be neglected, the peak value of the common-mode interference current is In the formula, is the peak value of the common-mode interference current ; Adding a common mode inductance after the common mode interference current is: In the formula, to add common mode inductance after the common mode interference current peak; Common mode inductance And the LC passive filter consisting of DC side voltage stabilizing capacitor C1, the secondary pulsating current is suppressed; By Fourier transform and carrier phase-shift modulation strategy on the energy storage system without common-mode inductance , the secondary ripple current is calculated: In the formula, is a secondary ripple current, is a DC side current component, is a battery internal resistance; By common mode inductance And DC side voltage stabilizing capacitor C1 constitute LC passive filter to suppress secondary pulsating current, after LC passive filter secondary pulsating current is: At this time, the second-order oscillation system is changed, and the second-order oscillation system suppresses the second pulsation current to a certain extent in a short time; The working modes of the steady flow unit are a boost mode and a buck mode respectively; Battery power generation: only the cascaded DC-DC converter G12 and the cascaded DC-DC converter G14 work in the boost mode, and only the cascaded DC-DC converter G11 and the cascaded DC-DC converter G13 work in the buck mode; Battery charging: only the cascaded DC-DC converter G11 and the cascaded DC-DC converter G13 work in the boost mode, and only the cascaded DC-DC converter G12 and the cascaded DC-DC converter G14 work in the buck mode; In the boost mode, the cascaded DC-DC converter G11 is turned on, and at this time, the cascaded DC-DC converter G12 and the cascaded DC-DC converter G14 are controlled by a modulation signal, the voltage output to the power module is raised, and the expression of the voltage output to the power module is: wherein , , is the input side voltage, is the voltage output to the power module, is the inductance current, according to the volt-second balance theory, we get: ； The system further comprises an alternating current isolation switch S1, a soft start switch S2, a reactor L1 and a soft start resistor R1; The soft start switch S2 is connected in series with the soft start resistor R1; The first end of the soft start switch S2 is connected to the first end of the alternating current isolation switch S1 and a medium-high voltage power grid; The second end of the soft start switch S2 is connected to the first end of the soft start resistor R1; The second end of the soft start resistor R1 is connected to the second end of the alternating current isolation switch S1 and the first end of the reactor L1; The second end of the reactor L1 is connected to the upper output end of the power module.

2. A control method applied to the DC-DC-based high-voltage direct plug-in energy storage system according to claim 1, characterized in that, The method comprises: Step S1: estimating the SOC condition of the battery pack, when the SOC condition of the battery pack is less than or equal to 20% of the power, executing step S2, otherwise, executing step S3; Step S2: not discharging, issuing a warning and coordinating other battery packs to discharge, and returning to execute step S1; Step S3: setting the output voltage of the DC-DC converter according to the fluctuation of the grid voltage, and selecting a working mode; Step S4: raising or lowering the voltage output to the power module based on the selected working mode; Step S5: calculating an increase or decrease in the voltage output to the power module; Step S6: determining whether the voltage difference between the voltage output to the power module and the grid voltage is less than 5% of the grid voltage, and if so, ending, otherwise, returning to perform step S3.

3. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the steps of the method of claim 2 when executing the program.

4. A storage medium having stored thereon a computer program, characterized in that The computer program implements the steps of the method of claim 2 when executed by the processor.

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