High-voltage energy storage device and starting method

Abstract

The application belongs to the technical field of electric power energy storage, and particularly relates to a high-voltage energy storage device and a starting method. The method comprises the following steps: when performing grid-connected starting by using a power grid to soft-start charge the capacitors of all power modules in the high-voltage energy storage device, charging the capacitor voltage of all power modules to a set voltage, wherein the set voltage is less than a starting voltage; alternately removing a set number of power modules for charging until the capacitor voltage of all power modules reaches the starting voltage; when the capacitor voltage of all power modules reaches the starting voltage, the power module charging is completed, and the high-voltage energy storage device is controlled to operate in a grid-connected mode. By alternately removing a set number of power modules, the capacitor voltage of the overall power modules is quickly raised, so that the capacitor voltage of all power modules can quickly reach the starting voltage, thereby solving the problems of long starting time of the high-voltage energy storage device or starting failure of part of the power modules.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power energy storage, and particularly relates to a high-voltage energy storage device and a starting method. BACKGROUND

[0002] As a new type of energy storage technology, the high-voltage energy storage technology can store energy in the valley stage of electricity consumption and release electric energy in the peak stage of electricity consumption, so as to alleviate the pressure of the power grid. It does not need to establish a transformer and has less pollution to the power grid, and is suitable for most electricity consumption conditions. The high-voltage energy storage device includes a circuit breaker, a soft start circuit and a plurality of power modules. Under the grid-connected condition, the alternating current grid charges the capacitors of the power modules through the soft start circuit. When the capacitor voltage reaches the starting value, the high-voltage energy storage device is successfully started. However, with the expansion of the electricity consumption scale, the number of power modules connected in series in the high-voltage energy storage device is also increasing. When the alternating current grid directly charges the capacitors of all the power modules through the soft start circuit, the capacitor voltage may be too small to meet the starting condition, resulting in that the high-voltage energy storage device takes too long to start or some power modules fail to start, thereby affecting the normal use of the high-voltage direct-hanging device. SUMMARY

[0003] The application aims to provide a high-voltage energy storage device and a starting method, so as to solve the problem that the high-voltage energy storage device takes too long to start or some power modules fail to start when the alternating current grid starts the high-voltage energy storage device due to too many power modules in the high-voltage energy storage device.

[0004] The application provides a high-voltage energy storage device starting method to solve the above technical problem, which includes the following steps:

[0005] 1) When performing grid-connected starting by soft starting charging the capacitors of all the power modules in the high-voltage energy storage device with the power grid, the capacitor voltages of all the power modules are charged to a set voltage, and the set voltage is less than the starting voltage;

[0006] 2) A set number of power modules are alternately removed for charging until the capacitor voltages of all the power modules reach the starting voltage;

[0007] 3) When the capacitor voltages of all the power modules reach the starting voltage, the charging of the power modules is completed, and the high-voltage energy storage device is controlled to operate in the grid-connected mode.

[0008] Further, the calculation formula of the set number is:

[0009] Cut_num=Rate_num-Upp_peak / Udc_rate*0.5

[0010] Wherein, Cut_num is the number of single-phase converter chain to be cut off power module, Rate_num is the rated power module number of single-phase converter chain, Upp_peak is the peak value of AC grid line voltage, Udc_rate is the rated operating voltage of power module.

[0011] Further, the power module to be cut off in rotation is a set number of power modules with higher voltage.

[0012] Further, when the grid-connected start is performed by using the battery to soft-start charge the capacitor of the power module, the battery charges the capacitor voltage of all power modules to the start voltage, the power module charging is completed, and the high-voltage energy storage device is controlled to operate in grid-connected mode; when the off-grid start is performed by using the battery to soft-start charge the capacitor of the power module, the battery charges the capacitor voltage of all power modules to the start voltage, the power module charging is completed, and the main loop grid-connected switch is closed to control the high-voltage energy storage device to operate in grid-connected mode.

[0013] The beneficial effects of the above technical solution are: the present application is an improved invention, and when the grid-connected start is performed by soft-start charging the capacitor in all power modules in the high-voltage energy storage device by the grid, if there are too many power modules and the grid voltage is not enough to charge the capacitor of all power modules to the start voltage, the sorting voltage boosting strategy is adopted, the capacitor voltage of all power modules is charged to a set voltage, and then part of the power modules are cut off in rotation, so that the grid charges the capacitor voltage of the cut-off power modules to the start voltage in turn, thereby the capacitor voltage of all power modules can be quickly charged to the start voltage, and the problems of long start time of the high-voltage energy storage device or start failure of part of the power modules are solved.

[0014] To solve the above technical problems, the present application further provides a high-voltage energy storage device, comprising power modules and a control module, the control module is used to control the grid to charge the capacitor of all power modules in the high-voltage energy storage device through a first soft-start loop to perform grid-connected start, the capacitor voltage of all power modules is charged to a set voltage, and the set voltage is less than the start voltage; a set number of power modules are cut off in rotation for charging until the capacitor voltage of all power modules reaches the start voltage; when the capacitor voltage of all power modules reaches the start voltage, the power module charging is completed, and the high-voltage energy storage device is controlled to operate in grid-connected mode.

[0015] Further, the calculation formula of the set number is:

[0016] Cut_num=Rate_num-Upp_peak / Udc_rate*0.5

[0017] Wherein, Cut_num is the number of power modules to be cut off in the single-phase converter chain, Rate_num is the number of rated power modules in the single-phase converter chain, Upp_peak is the peak value of the AC grid line voltage, and Udc_rate is the rated operating voltage of the power module.

[0018] Further, the power modules to be cut off in rotation are a set number of power modules with higher voltage.

[0019] Further, the control module is further configured to control the battery to start grid connection by charging the capacitors of the power modules through the second soft start circuit, charge the capacitor voltages of all the power modules to the starting voltage by the battery, complete the charging of the power modules, and control the high-voltage energy storage device to operate in grid connection; and control the battery to start off-grid by charging the capacitors of the power modules through the second soft start circuit, charge the capacitor voltages of all the power modules to the starting voltage by the battery, complete the charging of the power modules, close the grid connection switch of the main circuit, and control the high-voltage energy storage device to operate in grid connection.

[0020] Further, the control module is connected to the capacitor and the battery through a power taking circuit, and the power taking circuit converts the electric energy of the capacitor and the battery into electric energy suitable for the control module.

[0021] Further, a diode is arranged between the capacitor and the power taking circuit and between the battery and the power taking circuit to prevent reverse connection.

[0022] The above technical solution has the following beneficial effects: when the capacitors in all the power modules in the high-voltage energy storage device are soft-start charged by the grid to start grid connection under grid connection, if there are too many power modules and the grid voltage is not enough to charge the capacitors of all the power modules to the starting voltage, the sorting voltage boosting strategy is adopted, the capacitor voltages of all the power modules are first charged to a set voltage, and then part of the power modules are cut off in rotation, so that the capacitors of the cut-off power modules are charged to the starting voltage by the grid in rotation, thereby the capacitor voltages of all the power modules can be quickly charged to the starting voltage, and the problems of long starting time of the high-voltage energy storage device or failure of starting of part of the power modules are solved. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a high-voltage energy storage device starting method flowchart of the device embodiment of the present application;

[0024] Figure 2 is a high-voltage direct-hanging energy storage device main circuit system of the device embodiment of the present application;

[0025] Figure 3 is a battery soft-start charging system of the high-voltage direct-hanging energy storage device of the device embodiment of the present application;

[0026] Figure 4is the grid charging mode starting high-voltage direct-hanging energy storage device flow chart of the device embodiment of the present application.

[0027] Figure 5 is the battery charging mode starting high-voltage direct-hanging energy storage device flow chart of the device embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application more clear, the specific embodiments of the present application will be further described below with reference to the drawings.

[0029] The present application realizes the grid-connected start of high-voltage direct-hanging energy storage device by soft starting charging of the capacitors of all power modules in the high-voltage energy storage device through the grid. If there are many power modules and the grid voltage is not enough to charge the capacitors of all power modules to the starting voltage, the charging start is carried out by using the sorting and boosting strategy. The capacitor voltages of all power modules are first charged to the set voltage, and then part of the power modules are cut off by rotation, so that the capacitor voltages of the cut-off power modules are charged to the starting voltage by the grid in turn, thereby the capacitor voltages of all power modules can be quickly raised to the starting voltage, and the problems of long starting time of high-voltage energy storage device or failure of starting of part of the power modules are solved.

[0030] Device embodiment

[0031] The present application provides a kind of high-voltage energy storage device, it is suitable for cascading structure's high-voltage energy storage device, including power module, control module, first circuit breaker and first soft start circuit.Several power modules are connected in cascade and are connected to three-phase alternating current grid through first soft start circuit.The first soft start circuit includes first soft start resistance R and first contactor KM.In this embodiment, high-voltage energy storage device is high-voltage direct-hanging energy storage device, as shown in Figure 2 First soft start circuit is arranged on the main circuit of high-voltage direct-hanging energy storage device, first circuit breaker includes A-phase circuit breaker QF-A, B-phase circuit breaker QF-B and C-phase circuit breaker QF-C, and first contactor KM is main circuit grid-connected switch, including A-phase main circuit grid-connected switch KM-A, B-phase main circuit grid-connected switch KM-B and C-phase main circuit grid-connected switch KM-C.Filter reactor is further arranged between first soft start circuit and power module, for filtering multiple harmonics of main circuit.Power module includes converter, capacitor and inductor connected in sequence, and capacitor and inductor constitute LC filter.In this embodiment, converter is single-phase full-bridge converter composed of four IGBTs, for bidirectional power conversion.Control module is used to realize a kind of high-voltage energy storage device starting method, which realizes the grid-connected start of high-voltage direct-hanging energy storage device by grid charging mode, and specific process is as shown in Figure 1 And Figure 4

[0032] 1) close first circuit breaker in main circuit; ​

[0033] 2) The AC power grid charges the capacitors of all power modules through the first soft start resistor R;

[0034] 3) When the capacitor voltage of the power module after soft start charging is small and cannot meet the starting condition, a sorting boost strategy is used for charging: first, charge the capacitor voltage of all power modules to a set voltage, which is less than the starting voltage; in this embodiment, the set voltage is set to 500V; then, a certain number of power modules with higher voltage in each phase are cut off in turn to improve the capacitor voltage in the overall power module; the calculation formula for the number of power modules to be cut off is:

[0035] Cut_num = Rate_num - Upp_peak / Udc_rate * 0.5

[0036] Wherein, Cut_num is the number of power modules to be cut off in the single-phase converter chain, Rate_num is the rated power module number of the single-phase converter chain, Upp_peak is the peak value of the AC grid line voltage, and Udc_rate is the rated operating voltage of the power module.

[0037] 4) The capacitor voltage of all power modules reaches the starting voltage, and the power module charging is completed;

[0038] 5) Close the main loop grid connection switch KM, and after the main loop grid connection switch is closed, the pulse is removed, and the high-voltage energy storage device is connected to the grid.

[0039] The AC power grid side AC power is rectified into pulsating DC power by the single-phase full-bridge converter, and is stored in the battery after being filtered by the LC filter. The battery power can also be inverted into AC power by the single-phase full-bridge converter and sent back to the AC power grid side.

[0040] After the high-voltage direct-hanging energy storage device is started, the capacitor voltage in the power module and the battery voltage may be different. In order to reduce the current impact caused by the voltage difference, a second soft start circuit is provided between the power module and the battery module, as shown in Figure 3 The second soft start circuit includes a second soft start resistor R0 and a second contactor KM1 connected in series, and a third contactor KM2 connected in parallel with the second soft start resistor R0 and the second contactor KM1. After the power module charging is completed, the second contactor KM1 on the DC side of the power module is first closed, and then the third contactor KM2 on the DC side of the power module is closed. After the third contactor KM2 on the DC side of all power modules is closed, the main loop grid connection switch KM is closed. In order to further ensure safety, the battery module is also provided with a second circuit breaker.

[0041] The control module is connected with the capacitor and the battery through a power taking circuit, and the power taking circuit converts the electric energy of the capacitor and the battery into electric energy suitable for the control module; the power taking circuit includes a controller power supply unit, which takes electric energy from the capacitor and the battery and converts the high-voltage power supply into a power supply suitable for the voltage level of the control module; in the embodiment, the controller is a power module control board card arranged in the power module, and the controller power supply unit is a high-voltage power taking power supply, which takes electric energy from the capacitor and the battery in a redundant manner through a unidirectional diode provided with an anti-reverse function to supply power to the power module control board card.

[0042] The control module is also used for controlling the battery to start the power module in an off-grid mode through the second soft start circuit and the capacitor soft start charging mode.

[0043] Based on the above device, the high-voltage direct-hanging energy storage device starting method also includes starting the power module in an off-grid mode through the second soft start circuit and the capacitor soft start charging mode. Figure 5

[0044] 1) close the second contactor KM1 on the direct current side of the power module;

[0045] 2) the battery charges the capacitor of the power module through the second soft start resistor;

[0046] 3) after the power module is fully charged, the capacitor voltage approaches the battery voltage, at this time, the third contactor KM2 on the direct current side of the power module is closed;

[0047] 4) after all the modules are fully charged, the first circuit breaker of the main circuit is closed;

[0048] 5) after the first circuit breaker is closed, the main circuit grid-connected switch KM is closed, after the main circuit grid-connected switch is closed, the pulse is released, and the grid-connected operation is performed.

[0049] ​In order to meet the starting demand of high-voltage direct-hanging energy storage device compatible in grid-connected and off-grid, the high-voltage direct-hanging energy storage device starting method can start according to the actual working condition, so as to be compatible with grid-connected and off-grid conditions, and has wide application range. In the grid-connected condition, the capacitor in the power module of the high-voltage direct-hanging energy storage device can be powered from the AC side power grid or the DC side battery, but in order to save battery energy or avoid insufficient battery energy to charge to the starting voltage, the AC side power supply is preferred, and the power grid charges the capacitor in the power module through the AC side first soft start circuit. In the off-grid condition, the capacitor in the power module of the high-voltage direct-hanging energy storage device can only be powered from the DC side battery, and the battery charges the capacitor in the power module through the DC side second soft start circuit. When used, according to the actual condition, select which starting mode to use, the two starting modes do not interfere with each other, once a certain starting mode is selected, the other starting mode is not executed, and the protection and control logic related thereto is also not executed, so as to simplify the program execution process, and also improve the starting efficiency. The method comprises the following steps:

[0050] 1) Set the starting mode through the background, and the starting mode is grid-connected starting or off-grid starting;

[0051] 2) When the grid-connected starting is set, the high-voltage direct-hanging energy storage device is started by the AC side power grid charging starting mode;

[0052] 3) When the off-grid starting is set, the high-voltage direct-hanging energy storage device is started by the DC side battery charging starting mode.

[0053] Method embodiment

[0054] The application provides a high-voltage energy storage device starting method. The specific implementation process of the method has been described in detail in the device embodiment, which will not be repeated here.

Claims

1. A method of starting a high voltage energy storage device, the method comprising: Comprise the following steps: 1) when the grid is used to soft start charging the capacitors of all power modules in the high-voltage energy storage device to carry out grid-connected start, the capacitor voltage of all power modules is charged to a set voltage, which is less than the start voltage; 2) a set number of power modules are alternately cut off for charging until the capacitor voltage of all power modules reaches the start voltage; the calculation formula of the set number is: Cut_num = Rate_num–Upp_peak / Udc_rate*0.5 wherein, Cut_num is the number of power modules to be cut off in the single-phase converter chain, Rate_num is the rated power module number of the single-phase converter chain, Upp_peak is the peak value of the AC grid line voltage, and Udc_rate is the rated operating voltage of the power module; 3) when the capacitor voltage of all power modules reaches the start voltage, the power module charging is completed, and the high-voltage energy storage device is controlled to operate in grid-connected mode.

2. The high voltage energy storage device starting method of claim 1, wherein, The alternately cut-off power modules are a set number of power modules with higher voltage.

3. The method of claim 1, wherein the high voltage energy storage device is a capacitor. When the grid is used to soft start charging the capacitors of all power modules in the high-voltage energy storage device to carry out grid-connected start, the battery charges the capacitor voltage of all power modules to the start voltage, the power module charging is completed, and the high-voltage energy storage device is controlled to operate in grid-connected mode; when the battery is used to soft start charging the capacitors of all power modules in the high-voltage energy storage device to carry out off-grid start, the battery charges the capacitor voltage of all power modules to the start voltage, the power module charging is completed, the main loop grid-connected switch is closed, and the high-voltage energy storage device is controlled to operate in grid-connected mode.

4. A high voltage energy storage device comprising a power module and a control module, characterized in that, The control module is used to control the grid to charge the capacitors of all power modules in the high-voltage energy storage device through the first soft start loop to carry out grid-connected start, charge the capacitor voltage of all power modules to a set voltage, which is less than the start voltage, alternately cut off a set number of power modules for charging until the capacitor voltage of all power modules reaches the start voltage, and when the capacitor voltage of all power modules reaches the start voltage, the power module charging is completed, and the high-voltage energy storage device is controlled to operate in grid-connected mode; the calculation formula of the set number is: Cut_num = Rate_num–Upp_peak / Udc_rate*0.5 wherein, Cut_num is the number of power modules to be cut off in the single-phase converter chain, Rate_num is the rated power module number of the single-phase converter chain, Upp_peak is the peak value of the AC grid line voltage, and Udc_rate is the rated operating voltage of the power module.

5. The high pressure energy storage device of claim 4, wherein, The alternately cut-off power modules are a set number of power modules with higher voltage.

6. The high pressure energy storage device of claim 4, wherein, The control module is also used to control the battery to charge the capacitors of all power modules through the second soft start loop to carry out grid-connected start, charge the capacitor voltage of all power modules to the start voltage, complete the power module charging, and control the high-voltage energy storage device to operate in grid-connected mode; and used to control the battery to charge the capacitors of all power modules through the second soft start loop to carry out off-grid start, charge the capacitor voltage of all power modules to the start voltage, complete the power module charging, close the main loop grid-connected switch, and control the high-voltage energy storage device to operate in grid-connected mode.

7. The high pressure energy storage device of claim 4, wherein, The control module is connected with the capacitor and the battery through a power taking circuit, and the power taking circuit converts the electric energy of the capacitor and the battery into electric energy suitable for the control module.

8. The high pressure energy storage device of claim 7, wherein, A reverse prevention diode is arranged between the capacitor and the power taking circuit and between the battery and the power taking circuit.

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