An energy storage converter system with adaptive function and off-grid starting method thereof

Abstract

The present invention relates to an energy storage converter system with adaptive function and an off-grid starting method thereof, the system comprising: a user power grid, a battery energy storage device and an energy management system, the battery energy storage device comprising a battery and an energy storage converter, the energy storage converter comprising a supporting capacitor, a power unit, an LCL filter, an AC contactor, and an energy storage converter controller; the energy storage converter controller comprising a DSP module and an FPGA module, the FPGA module being connected to the power unit, the AC contactor, and the energy management system, and the FPGA module being connected to the DSP module to realize a coordinated control function. The present invention can adaptively judge the voltage amplitude of the power grid and send an off-grid enabling signal to the energy storage converter controller, and can realize the off-grid starting and operation of hundreds of energy storage converters. No matter what state the current off-grid power grid is in, the energy storage converter can be adaptively started, and finally an off-grid power grid is established, meeting the off-grid operation requirements of high-power loads.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage converters, and in particular to an energy storage converter system with an adaptive function and an off-grid starting method thereof. Background Art

[0002] The power storage converter (PCS) can be used to control the charging and discharging process of the battery, perform AC / DC conversion, and directly supply power to the AC load when there is no power grid. Existing power storage converters can only complete off-grid startup independently by one unit, or two units can be started at the same time to enter off-grid operation. When there are dozens or hundreds of power storage converters in the energy storage system, there is no flexible and reliable implementation method with adaptive functions for the off-grid startup of all the power storage converters, which makes it difficult to meet the off-grid operation requirements of high-power loads. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to propose an energy storage converter system with adaptive function and an off-grid starting method thereof, thereby solving the problem of adaptive off-grid starting of large-scale energy storage converters.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] An off-grid starting method for an energy storage converter system with an adaptive function, the energy storage converter system with an adaptive function comprises a user power grid, a battery energy storage device and an energy management system, the battery energy storage device comprises a battery and an energy storage converter, the energy storage converter comprises a supporting capacitor, a power unit, an LCL filter, an AC contactor and an energy storage converter controller; the battery and the supporting capacitor, the power unit, the LCL filter, the AC contactor are sequentially connected to the user power grid, the energy storage converter controller comprises a DSP module, an FPGA module, a PWM signal generation module, an analog quantity acquisition channel, a DP communication port, a DI port and a DO port, the FPGA module is connected to the state end and the control end of the AC contactor through the DI port and the DO port, the FPGA module is connected to the energy management system through the DP communication port, the FPGA module is connected to the power unit through the PWM signal generation module, the FPGA module collects the AC and DC signals of the energy storage converter and the power grid voltage through the analog quantity acquisition channel; the FPGA module is connected to the DSP module to realize the coordinated control function; the battery energy storage device is incorporated into the user power grid after off-grid to form an off-grid power grid, and the off-grid starting method comprises the following steps:

[0006] Step 1: The energy management system determines whether the energy storage converter meets the off-grid startup conditions. If the off-grid startup conditions are met, the next step of off-grid control logic is entered;

[0007] Step 2: The energy management system determines the number of energy storage converters for initial startup according to the capacity of the transformer, and sends an off-grid enable signal to the energy storage converter for initial startup. After the energy storage converter receives the off-grid enable signal from the energy management system, the energy storage converter starts off-grid;

[0008] Step 3: The energy management system determines the status signal sent back by the energy storage converter to determine whether the energy storage converter has been started;

[0009] Step 4: After the energy storage converter is started, the energy management system starts the remaining energy storage converters according to actual demand, and the remaining energy storage converters are started off-grid;

[0010] Step 5: When the battery power is low, the energy management system stops the off-grid enabling signal of the energy storage inverter;

[0011] The specific implementation method of the off-grid startup of the energy storage converter is:

[0012] After the FPGA module receives the off-grid enable signal from the energy management system, the analog acquisition channel collects the off-grid grid voltage and the energy storage converter output voltage signal; the DI port and DO port receive the switch status of the AC contactor and control the contactor to close or open; the off-grid voltage is processed by the FPGA module to determine whether there is voltage in the off-grid grid; according to the principle of off-grid voltage adaptation, the off-grid startup of the energy storage converter is divided into the following two situations for processing:

[0013] ⑴ When the off-grid grid already has voltage and the off-grid grid is connected to a small amount of load or no load, the energy storage converter controller controls the PWM signal generation module to unlock its own pulses, outputs the PWM signal to the power unit, locks the off-grid grid voltage through the phase-locked loop, and establishes its own output voltage according to the amplitude and phase of the current off-grid grid voltage; the output voltage is completely consistent with the current off-grid grid voltage, and the energy storage converter controller controls the closing of the AC contactor to complete the startup of the energy storage converter;

[0014] ⑵When the energy storage inverter is started off-grid, if no voltage is detected in the off-grid power grid and no load is connected, the energy storage inverter or multiple energy storage inverters are used as the initial startup energy storage inverters. The energy storage inverter controller first controls the closing of the AC contactor through the DO port. After detecting that the AC contactor is closed through the DI port, the controller controls the PWM signal generation module to unblock the pulse and output the PWM signal. The off-grid voltage establishes the off-grid power grid in the form of a soft start, completing the establishment of the initial voltage for off-grid operation.

[0015] The off-grid starting conditions in step 1 are: the battery power is sufficient, there is load, and the user's power grid is ready for off-grid use.

[0016] In step 4, the energy management system starts the remaining energy storage inverters according to the load size. When the load increases, the number of energy storage inverters started is increased, and an off-grid enable signal is sent to the energy storage inverter that needs to be started; when the load decreases, the off-grid enable signal is stopped.

[0017] The FPGA module includes an off-grid startup control circuit, which includes a selector A1, a comparator A2, an AND gate A3, an RS trigger A4, an AND gate A5, a comparator A6, an AND gate A7, a selector A8 and an RS trigger A9; the two input terminals S1 and S2 of the selector A1 are respectively connected to an off-grid enable signal and a switch closure signal, the switch closure signal is a closed state signal of the AC contactor, the two input terminals of the comparator A2 are connected to an off-grid power grid voltage amplitude signal and K1, the output terminal of the comparator A2 is connected to an input terminal of the AND gate A3, the other input terminal of the AND gate A3 is connected to the off-grid enable signal, the output terminal of the AND gate A3 is connected to the sel terminal of the selector A1 and the sel terminal of the selector A8, the output terminal Q of the selector A1 is connected to an input terminal S of the RS trigger A4, the other input terminal of the RS trigger A4 is connected to the off-grid power grid voltage amplitude signal K1, the output terminal of the comparator A2 is connected to an input terminal of the AND gate A3, the other input terminal of the AND gate A3 is connected to the off-grid enable signal, the output terminal of the AND gate A3 is connected to the sel terminal of the selector A1 and the sel terminal of the selector A8, the output terminal Q of the selector A1 is connected to an input terminal S of the RS trigger A4, and the other input terminal of the RS trigger A4 is connected to the off-grid power grid voltage amplitude signal K1. R is connected to a fault and shutdown signal; the output end Q of the RS trigger A4 is respectively connected to an input end of the AND gate A5 and the AND gate A7, the other input end of the AND gate A5 is connected to a PWM signal, and the output end of the AND gate A5 outputs a PWM signal generation; the two input ends of the comparator A6 are respectively connected to the output voltage amplitude of the energy storage converter and K2, the output end of the comparator A6 is connected to the other input end of the AND gate A7, the output end of the AND gate A7 is connected to an input end S1 of the selector A8, the other input end S2 of the selector A8 is connected to a value 1, the output end Q of the selector A8 is connected to an input end S of the RS trigger A9, the other input end R of the RS trigger A9 is connected to a fault and shutdown signal, and the output end Q of the RS trigger A9 outputs a contactor closing signal; the K1 is the minimum detection value for judging that there is no off-grid grid voltage; K2 is the threshold value established by the output voltage.

[0018] The PWM signal is a logic signal generated by the FPGA module according to the given voltage calculated by the DSP module and the triangular carrier; the output voltage amplitude signal of the energy storage converter is the output voltage signal collected through the analog channel and then processed and calculated by the FPGA module and the DSP module; the off-grid enable signal is the signal sent by the energy management system through the FPGA module; the switch closing signal is the closed state signal of the AC contactor detected by the DI port; the off-grid power grid voltage amplitude signal is the off-grid power grid voltage signal collected through the analog channel and then processed and calculated by the FPGA module and the DSP module; the fault and shutdown signal is the FPGA module that performs logical operations based on the operation status of the energy storage converter.

[0019] The user power grid includes a grid-connected switch, a load, a step-up transformer and a grid-connected point PCC. The grid-connected point PCC is connected to the load and the step-up transformer through the grid-connected switch. When the grid-connected switch is disconnected, the battery energy storage device outputs an off-grid voltage through the step-up transformer to provide power to the load.

[0020] The advantages and positive effects of the present invention are:

[0021] 1. The present invention can realize the off-grid startup and operation of hundreds of energy storage inverters by adaptively judging the grid voltage amplitude through the energy storage inverter controller and sending off-grid enable signals to the energy storage inverter controller at different times according to the energy management system. No matter what state the current off-grid grid is in, the energy storage inverter can be adaptively started and finally establish an off-grid grid to access various off-grid loads or emergency loads. When dozens or hundreds of energy storage inverters are started, the grid can reach the MW scale and meet the off-grid operation requirements of high-power loads.

[0022] 2. The off-grid power grid established by the present invention is stable and reliable, and the energy storage converter can be flexibly connected and exited at any time, and the power grid is not affected. The present invention can complete the establishment of the power grid in as fast as ten seconds without a power grid, and realize the zero-start boosting of the transformer, the black start of the power grid, and the high-power emergency power supply and other applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a hardware connection diagram of off-grid startup of the energy storage system of the present invention;

[0024] Figure 2 It is an off-grid startup control circuit diagram inside the FPGA in the energy storage converter controller of the present invention;

[0025] Figure 3 It is the overall flow chart of the off-grid startup of the EMS controlled energy storage system of the present invention;

[0026] Figure 4 It is a flow chart of the off-grid starting process of the energy storage converter of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings.

[0028] An energy storage converter system with adaptive function, such as Figure 1 As shown, it includes a user power grid, a battery energy storage device and an energy management system (EMS). The battery energy storage device is connected to the energy management system and the user power grid to realize the off-grid starting function of the energy storage converter system.

[0029] The user power grid includes a grid-connected switch, a load, a step-up transformer and a grid-connected point PCC. The grid-connected point PCC is connected to the load and the step-up transformer through the grid-connected switch. When the grid-connected switch is disconnected, the energy storage inverter outputs an off-grid voltage through the step-up transformer to provide power to the load.

[0030] The battery energy storage device includes a battery and an energy storage converter. The battery is composed of a lithium battery and a BMS system connected together. The energy storage converter is a key device for realizing the energy conversion between the power grid and the battery. The energy storage converter includes a supporting capacitor, a power unit, an LCL filter, an AC contactor, an energy storage converter controller, etc. The energy of the battery is filtered by the supporting capacitor, converted into AC power by the power unit, and then sent to the off-grid power grid (user power grid) through the LCL filter and the AC contactor. The energy storage converter controller includes a DSP module, an FPGA module, a PWM signal generation module, an analog quantity acquisition channel, a DP communication port, a DI port (digital input port) and a DO port (digital output port). The energy storage converter controller uses DSP and FPGA as core control devices. The FPGA module is connected to the state end and control end of the AC contactor through the DI port and the DO port to realize the contactor state acquisition and contactor closure control functions. The FPGA module is connected to the energy management system through the DP communication port. On the one hand, it receives the command of the energy management system, and on the other hand, it sends the state information of the energy storage converter to the energy management system. The FPGA module is connected to the PWM signal generation module to generate an IGBT pulse signal and send it to the power unit. The analog quantity acquisition channel is connected to the output end of the battery to collect the DC voltage and DC current signals of the battery, and is connected to the input end of the AC contactor to collect the AC voltage and current signals output by the energy storage converter, and is connected to the output end of the AC contactor to collect the grid voltage. The FPGA module is connected to the DSP module, and the FPGA module sends the received information to the DSP module, which processes the information and then sends it out.

[0031] like Figure 2As shown, the FPGA module is built with an off-grid startup control circuit, which includes a two-choice selector A1, a comparator A2, an AND gate A3, an RS trigger A4, an AND gate A5, a comparator A6, an AND gate A7, a two-choice selector A8 and an RS trigger A9. The two input terminals S1 and S2 of the two-choice selector A1 are respectively connected to the off-grid enable signal and the switch closure signal, the two input terminals of the comparator A2 are connected to the grid amplitude signal and K1, the output terminal of the comparator A2 is connected to an input terminal of the AND gate A3, the other input terminal of the AND gate A3 is connected to the off-grid enable signal, the output terminal of the AND gate A3 is connected to the sel terminal of the two-choice selector A1 and the sel terminal of the two-choice selector A8, the output terminal Q of the selector A1 is connected to an input terminal S of the RS trigger A4, and the other input terminal R of the RS trigger A4 is connected to the fault and shutdown signal. The output terminal Q of RS trigger A4 is respectively connected to one input terminal of AND gate A5 and AND gate A7, the other input terminal of AND gate A5 is connected to PWM signal, and the output terminal of AND gate A5 outputs PWM signal generation. The two input terminals of the comparator A6 are respectively connected to the output voltage amplitude and K2, the output terminal of comparator A6 is connected to the other input terminal of AND gate A7, the output terminal of AND gate A7 is connected to one input terminal S1 of two-choice comparator A8, the other input terminal S2 of comparator A8 is connected to 1, the output terminal Q of comparator A8 is connected to one input terminal S of RS trigger 9, the other input terminal R of RS trigger A9 is connected to fault and shutdown signal, and the output terminal Q of RS trigger A9 outputs contactor closing signal.

[0032] The above-mentioned PWM signal is a logic signal generated by the FPGA module according to the comparison between the given voltage calculated by the DSP module and the triangular carrier; the output voltage amplitude is the output voltage signal collected through the analog channel of the controller, and then processed and calculated by the FPGA and DSP; the off-grid enable is the signal sent by the EMS to the FPGA via DP communication; the switch closure is the closed state signal of the AC contactor detected by the DI port of the controller; the grid amplitude is the off-grid grid voltage signal collected through the analog channel of the controller, and then processed and calculated by the FPGA and DSP; the fault and shutdown signals are logically calculated by the FPGA according to the operation status of the energy storage converter.

[0033] The above circuit mainly realizes the following functions:

[0034] (1) A1~A4 realize PMW pulse output enable function:

[0035] When the sel terminal of the two-to-one comparator A1 is 1, that is, the output of A3 is 1, S2 is selected to correspond to the contactor closed state signal, and when sel is 0, S1 is selected to correspond to the off-grid enable signal.

[0036] When the grid amplitude is less than K1, the comparator A2 outputs 1, and K1 is the minimum detection value for judging that there is no grid voltage.

[0037] AND gate A3 performs an AND operation on the off-grid enable signal and the result of comparator A2.

[0038] When the S terminal of RS trigger A4 is 1, the output signal is 1, the pulse is unlocked, and the PWM waveform is output. When the R terminal is 1, that is, when the device fails or stops, the pulse is blocked.

[0039] (2) AND gate A5 realizes the PWM pulse signal generation function:

[0040] The PWM signal and the pulse enable signal output by the RS comparator A4 are operated by the A5 AND gate to generate a PWM signal to the PWM signal generation module, and finally act on the IGBT.

[0041] (3) A6~A9 generate the main switch closing command function.

[0042] When the output voltage amplitude is greater than K2, the comparator A6 outputs 1. K2 is the threshold value for the output voltage.

[0043] When the A4 pulse output is enabled and the A6 output voltage is established, the AND gate A7 output is 1.

[0044] When the sel terminal of the two-to-one selector A8 is 1, that is, the output of A3 is 1, the corresponding output of S2 is 1. When sel is 0, S1 is selected corresponding to the output signal of A7.

[0045] When the S terminal of RS trigger A9 is 1, that is, A8 output is 1, A9 output signal is 1, the DO port output is high level, the coil of the AC contactor is controlled to be attracted, and the contactor state becomes closed. When R is 1, that is, when the equipment fails or stops, the DO port output is low level, the coil of the AC contactor is controlled to be disconnected, and the contactor state is disconnected.

[0046] The above logic can realize that when the EMS sends an off-grid enable signal and the off-grid power grid amplitude is less than K1, A1 and A8 both select S2, A9 controls the closing of the AC contactor, and when A1 detects the switch closing signal, A4 outputs 1, that is, the PWM signal is enabled, and the PWM signal output by A5 passes through the generating circuit to the IGBT, and the off-grid voltage is generated in a soft start mode, and the off-grid start of the energy storage converter is completed. When the off-grid power grid has been established and the off-grid power grid amplitude is greater than K1, A2 outputs 0, A1 and A8 both select S1, and after the EMS sends the off-grid enable, A4 outputs 1, that is, the PWM signal is enabled, and the PWM signal output by A5 passes through the generating circuit to the IGBT, and the energy storage converter outputs the AC voltage. When the output voltage satisfies the requirement of being greater than K2, A7 outputs 1, and after A8, A9 is set to 1, and the DO port output is high level, which controls the coil of the AC contactor to be attracted, and the energy storage converter completes the grid connection, and the off-grid start is completed at the same time.

[0047] The energy management system (EMS) acts as a host computer to exchange data with the energy storage converter to realize the control function of the energy storage converter.

[0048] Based on the above system, the present invention also provides an off-grid startup method for an energy storage inverter system with an adaptive function, which controls the startup sequence of the energy storage inverter by sending an off-grid enable signal to each energy storage inverter through an energy management system (EMS), and completes the off-grid startup of a MW-level energy storage system. The process can be completed in as fast as ten seconds. Figure 3 As shown, the off-grid startup method of the system includes the following steps:

[0049] Step 1: EMS determines whether the energy storage system meets the off-grid startup conditions. If the conditions are met, it enters the off-grid control logic.

[0050] When the battery power is low, there is no load, the power grid does not meet the off-grid conditions, and the off-grid start conditions are not met, the off-grid operation stops.

[0051] Step 2: The EMS determines the number of initial startup energy storage converters according to the transformer capacity, and sends an off-grid enable signal to the initial startup energy storage converters.

[0052] Step 3: After receiving the off-grid enable signal from the EMS, the energy storage converter starts off-grid and sends a status signal to the EMS. The specific method is as follows:

[0053] This step is achieved through the energy storage converter controller. Figure 4As shown in the figure, after the FPGA receives the off-grid enable signal from the host computer through DP communication, the analog acquisition channel collects signals such as the grid voltage and output voltage; the DI and DO ports receive the switch status of the AC contactor and control the contactor to close or open. The off-grid voltage is processed by the FPGA to determine whether there is voltage in the off-grid grid. According to the principle of adaptive off-grid voltage, the system processes the off-grid startup of the energy storage converter in two situations.

[0054] In the first case, when the off-grid grid already has voltage and the grid is connected to a small amount of load or no load, the energy storage converter controller controls the PWM signal generation module to unlock its own pulses, outputs the PWM signal to the IGBT, locks the off-grid grid voltage through the phase-locked loop, and establishes its own output voltage according to the amplitude and phase of the current grid voltage. The output voltage is completely consistent with the current grid voltage, and the energy storage converter controller controls the closing of the AC main switch to complete the startup of the energy storage converter.

[0055] In the second case, when the energy storage inverter is started off-grid, no voltage is detected in the off-grid grid and no load is connected, that is, no energy storage inverter is currently started. The energy storage inverter or multiple energy storage inverters are used as initial startup energy storage inverters, and the controller first controls the closing of the AC contactor through the DO port. After the AC contactor is detected to be closed through the DI port, the controller controls the PWM signal generation module to unlock the pulse and output the PWM signal. The off-grid voltage establishes the off-grid grid in the form of soft start according to a certain slope, completing the establishment of the initial voltage of the off-grid operation.

[0056] Step 4: The EMS determines the status signal sent back by the energy storage converter to determine whether the energy storage converter has been started.

[0057] Step 5: After the energy storage converter is started, the EMS starts the remaining energy storage converters according to actual demand. This is mainly based on the load size. When the load increases, the number of start-up units is increased, and the off-grid enable signal is sent to the energy storage converter that needs to be started; when the load decreases, the off-grid enable signal can be stopped.

[0058] Step 6: When the battery power is low, the EMS stops the off-grid enabling signal of the energy storage inverter.

[0059] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. An off-grid starting method for an energy storage converter system with an adaptive function, characterized in that: The energy storage converter system with adaptive function includes a user power grid, a battery energy storage device and an energy management system. The battery energy storage device includes a battery and an energy storage converter. The energy storage converter includes a supporting capacitor, a power unit, an LCL filter, an AC contactor and an energy storage converter controller. The battery and the supporting capacitor, the power unit, the LCL filter, the AC contactor are connected to the user power grid in sequence. The energy storage converter controller includes a DSP module, an FPGA module, a PWM signal generation module, an analog quantity acquisition channel, a DP communication port, a DI port and a DO port. The FPGA module is connected to the state end and the control end of the AC contactor through the DI port and the DO port. The FPGA module is connected to the energy management system through the DP communication port. The FPGA module is connected to the power unit through the PWM signal generation module. The FPGA module collects the AC and DC signals of the energy storage converter and the power grid voltage through the analog quantity acquisition channel. The FPGA module is connected to the DSP module to realize the coordinated control function. The battery energy storage device is incorporated into the user power grid after off-grid to form an off-grid power grid. The off-grid startup method includes the following steps: Step 1: The energy management system determines whether the energy storage converter meets the off-grid startup conditions. If the off-grid startup conditions are met, the next step of off-grid control logic is entered; Step 2: The energy management system determines the number of energy storage converters for initial startup according to the capacity of the transformer, and sends an off-grid enable signal to the energy storage converter for initial startup. After the energy storage converter receives the off-grid enable signal from the energy management system, the energy storage converter starts off-grid; Step 3: The energy management system determines the status signal sent back by the energy storage converter to determine whether the energy storage converter has been started; Step 4: After the energy storage converter is started, the energy management system starts the remaining energy storage converters according to actual demand, and the remaining energy storage converters are started off-grid; Step 5: When the battery power is low, the energy management system stops the off-grid enabling signal of the energy storage inverter; The specific implementation method of the off-grid startup of the energy storage converter is: After the FPGA module receives the off-grid enable signal from the energy management system, the analog acquisition channel collects the off-grid grid voltage and the energy storage converter output voltage signal; the DI port and DO port receive the switch status of the AC contactor and control the contactor to close or open; the off-grid voltage is processed by the FPGA module to determine whether there is voltage in the off-grid grid; according to the principle of off-grid voltage adaptation, the off-grid startup of the energy storage converter is divided into the following two situations for processing: ⑴ When the off-grid grid already has voltage and the off-grid grid is connected to a small amount of load or no load, the energy storage converter controller controls the PWM signal generation module to unlock its own pulses, outputs the PWM signal to the power unit, locks the off-grid grid voltage through the phase-locked loop, and establishes its own output voltage according to the amplitude and phase of the current off-grid grid voltage; the output voltage is completely consistent with the current off-grid grid voltage, and the energy storage converter controller controls the closing of the AC contactor to complete the startup of the energy storage converter; ⑵When the energy storage inverter is started off-grid, if no voltage is detected in the off-grid power grid and no load is connected, the energy storage inverter or multiple energy storage inverters are used as the initial startup energy storage inverters. The energy storage inverter controller first controls the closing of the AC contactor through the DO port. After detecting that the AC contactor is closed through the DI port, the controller controls the PWM signal generation module to unblock the pulse and output the PWM signal. The off-grid voltage establishes the off-grid power grid in the form of a soft start, completing the establishment of the initial voltage for off-grid operation.

2. The off-grid starting method of an energy storage converter system with adaptive function according to claim 1, characterized in that: The off-grid starting conditions in step 1 are: the battery power is sufficient, there is load, and the user's power grid is ready for off-grid use.

3. The off-grid starting method of an energy storage converter system with adaptive function according to claim 1, characterized in that: In step 4, the energy management system starts the remaining energy storage inverters according to the load size. When the load increases, the number of energy storage inverters started is increased, and an off-grid enable signal is sent to the energy storage inverter that needs to be started; when the load decreases, the off-grid enable signal is stopped.

4. The off-grid starting method of an energy storage converter system with adaptive function according to claim 1, characterized in that: The FPGA module includes an off-grid startup control circuit, which includes a selector A1, a comparator A2, an AND gate A3, an RS trigger A4, an AND gate A5, a comparator A6, an AND gate A7, a selector A8 and an RS trigger A9; the two input terminals S1 and S2 of the selector A1 are respectively connected to an off-grid enable signal and a switch closure signal, the switch closure signal is a closed state signal of the AC contactor, the two input terminals of the comparator A2 are connected to an off-grid power grid voltage amplitude signal and K1, the output terminal of the comparator A2 is connected to an input terminal of the AND gate A3, the other input terminal of the AND gate A3 is connected to the off-grid enable signal, the output terminal of the AND gate A3 is connected to the sel terminal of the selector A1 and the sel terminal of the selector A8, the output terminal Q of the selector A1 is connected to an input terminal S of the RS trigger A4, and the RS trigger A4 The other input end R is connected to the fault and shutdown signal; the output end Q of the RS trigger A4 is respectively connected to an input end of the AND gate A5 and the AND gate A7, the other input end of the AND gate A5 is connected to the PWM signal, and the output end of the AND gate A5 outputs the PWM signal generation; the two input ends of the comparator A6 are respectively connected to the output voltage amplitude of the energy storage converter and K2, the output end of the comparator A6 is connected to the other input end of the AND gate A7, the output end of the AND gate A7 is connected to an input end S1 of the selector A8, the other input end S2 of the selector A8 is connected to the value 1, the output end Q of the selector A8 is connected to an input end S of the RS trigger A9, the other input end R of the RS trigger A9 is connected to the fault and shutdown signal, and the output end Q of the RS trigger A9 outputs the contactor closing signal; the K1 is the minimum detection value for judging that there is no off-grid power grid voltage; K2 is the threshold value for output voltage establishment.

5. The off-grid starting method of the energy storage converter system with adaptive function according to claim 4, characterized in that: The PWM signal is a logic signal generated by the FPGA module according to the given voltage calculated by the DSP module and the triangular carrier; the output voltage amplitude signal of the energy storage converter is the output voltage signal collected through the analog channel and then processed and calculated by the FPGA module and the DSP module; the off-grid enable signal is the signal sent by the energy management system through the FPGA module; the switch closing signal is the closed state signal of the AC contactor detected by the DI port; the off-grid power grid voltage amplitude signal is the off-grid power grid voltage signal collected through the analog channel and then processed and calculated by the FPGA module and the DSP module; the fault and shutdown signal is the FPGA module that performs logical operations based on the operation status of the energy storage converter.

6. The off-grid starting method of an energy storage converter system with adaptive function according to claim 1, characterized in that: The user power grid includes a grid-connected switch, a load, a step-up transformer and a grid-connected point PCC. The grid-connected point PCC is connected to the load and the step-up transformer through the grid-connected switch. When the grid-connected switch is disconnected, the battery energy storage device outputs an off-grid voltage through the step-up transformer to provide power to the load.

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