A novel energy storage device and control method thereof

Abstract

The application provides a novel energy storage device and a control method thereof. The novel energy storage device is a chain type cascade multilevel structure, comprising a plurality of novel energy storage converter modules. The plurality of novel energy storage converter modules are connected in series in sequence from top to bottom to form a single-path cascade multilevel energy storage structure. Three single-path cascade multilevel energy storage structures are connected in star or delta to form a novel energy storage device with a star structure or a delta structure. The novel energy storage converter module comprises a full-bridge converter module. One or more DC converter modules are connected in parallel at the DC side capacitor C1 end of the full-bridge converter module. The output end of each DC converter module is connected to a battery pack. The novel energy storage device has the advantages of high-voltage direct hanging, large capacity of a single machine, high redundancy of power modules, small harmonic content of AC / DC output, low system loss and the like. The novel full-bridge energy storage unit module has DC control capability. The DC side harmonics can be effectively suppressed through control algorithm design, and the service life of the battery pack is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage control, in particular to a novel energy storage device and a control method thereof. BACKGROUND

[0002] At present, the structure of the converter in the energy storage device mostly uses the traditional two-level and three-level structure. The traditional structure is simple to control, high in efficiency and low in cost, but cannot be directly connected to a high-voltage system, and has a small capacity. If applied to a high-voltage scene, a step-up transformer needs to be connected, which reduces the overall energy conversion efficiency. Parallel connection of multiple energy storage devices has the problems of high failure rate and easy to cause system resonance.

[0003] The novel energy storage device based on the cascaded topology structure adds a DC converter, has the advantages of high-voltage direct hanging, single-machine large capacity, high redundancy of power modules, small harmonic content of AC / DC output, and low system loss, and can be widely applied to wind and light power stations, substations, thermal power plants and other scenes. SUMMARY

[0004] In order to solve the technical problems proposed in the background art, the present application provides a novel energy storage device and a control method thereof, which has the advantages of high-voltage direct hanging, single-machine large capacity, high redundancy of power modules, small harmonic content of AC / DC output, and low system loss, and can be widely applied to wind and light power stations, substations, thermal power plants and other scenes.

[0005] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the present application:

[0006] A novel energy storage device, which is a chain-type cascaded multi-level structure, comprises a plurality of novel energy storage converter modules, the plurality of novel energy storage converter modules are connected in series in an up-down manner to form a single-path cascaded multi-level energy storage structure, and three single-path cascaded multi-level energy storage structures are connected in a star type or an angle type to form a novel energy storage device in a star type structure or an angle type structure.

[0007] The novel energy storage converter module comprises a full-bridge converter module and a DC converter module, one or more DC converter modules are connected in parallel at the DC side capacitor C1 end of the full-bridge converter module, and the output end of each DC converter module is connected to a battery pack.

[0008] Further, the DC converter module is a DC chopper circuit structure, the output end of the DC converter module is further connected to a filter reactor L11...L1n and a filter capacitor C11...C1n, and the DC converter module further comprises a DC circuit breaker K11...K1n, and the output end of the DC converter module is connected to a battery pack Bat11, Bat1n through the DC circuit breaker K11...K1n.

[0009] Further, the input end of the full-bridge converter module is also provided with a bypass switch CB1.

[0010] Further, the novel energy storage device cascade structure is also connected in series with a main circuit breaker K1, a charging resistor R and a filter reactor L, and a bypass circuit breaker K2 is connected in parallel across the charging resistor R.

[0011] A control method of the novel energy storage device, the control method of the novel energy storage device comprising:

[0012] 1) The main circuit breaker K1 is closed, the full-bridge capacitor C1 of the energy storage device is charged through the charging resistor R, after the charging is completed, K2 is closed, the charging resistor R is bypassed, at this time, the full-bridge converter module of the device is unlocked, the device has inductive and capacitive idle operation modes, and can exchange reactive power to the system;

[0013] 2) The filter capacitors C11...C1n can be charged to a voltage deviation of less than 5V from the battery pack by unlocking the DC converter module, at this time, the battery pack Bat11, Bat1n is connected by closing the DC circuit breakers K11, K1n, at this time, the device has four-quadrant operation capability, and can output any active and reactive power within the rated capacity;

[0014] 3) The DC-DC converter module is a chopper circuit structure, the output DC voltage is adjusted by adjusting the duty cycle of the IGBT switch of the DC-DC converter module, so as to achieve the goal of controlling the current flowing into the battery pack;

[0015] The control method of the novel energy storage device comprises an AC control part and a DC control part.

[0016] Further, the AC control part is composed of a phase-locked loop, a voltage loop, a current loop, SWPM control, system redundancy control, unit redundancy control, and phase-to-phase SOC balance control; the control target is the AC side output current Iab, Icb, Ica, and includes the following steps:

[0017] Step 1, first, the frequency f=2π / ω and the phase θ of the system voltage are calculated by the phase-locked loop, and the three-phase voltage and the three-phase current of the system are converted into Ug_d, Ug_q in the DQ coordinate system and Id_Fbk, Iq_Fbk by the voltage frequency and phase;

[0018] Step 2, the reactor voltage drop UL_d, UL_q is calculated by the current loop according to the active instruction current Id_ref and the reactive instruction current Iq_ref;

[0019] Step 3, system voltage feed forward Ug_d, Ug_q plus reactor voltage drop UL_d, UL_q, then through park transformation to calculate three-phase total modulation wave VmodAB, VmodBC, VmodCA or VmodA, VmodB, VmodC;

[0020] Step 4, the last three-phase modulation wave through SPWM to calculate the pulse control command required to control IGBT;

[0021] The above variables are described as follows:

[0022] f: system voltage frequency;

[0023] ω: system voltage angular frequency;

[0024] θ: system phase;

[0025] Ug_d: system active voltage in DQ coordinate system;

[0026] Ug_q: system reactive voltage in DQ coordinate system;

[0027] Id_Fbk: system active current in DQ coordinate system;

[0028] Iq_Fbk: system reactive current in DQ coordinate system;

[0029] Id_ref: active instruction current;

[0030] Iq_ref: reactive instruction current;

[0031] UL_d: active voltage of filter reactor L;

[0032] UL_q: reactive voltage of filter reactor L;

[0033] Ug_d: system active voltage feed forward;

[0034] Ug_q: system reactive voltage feed forward;

[0035] VmodAB, VmodBC, VmodCA: three-phase total modulation wave when connected in delta;

[0036] VmodA, VmodB, VmodC: three-phase total modulation wave when connected in star;

[0037] Iab, Icb, Ica are AC side output currents, and are denoted as Ia, Ib, Ic when connected in star.

[0038] Further, the system redundancy control bypasses the faulty energy storage unit module and calculates the maximum active output capability of the energy storage device after bypassing the unit, performs instruction limiting to avoid overcurrent of the battery in the energy storage device, and calculates the capacitor C1 voltage instruction value UdcRef to ensure that the modulation degree of the energy storage device after bypassing the unit remains unchanged.

[0039] Further, the system redundancy control includes the following method:

[0040] When the faulty unit is bypassed, the system redundancy control calculates the active current output capability of the phase after bypassing according to the number and position of the bypassed units, and limits the active instruction Id_ref of the phase. The calculation method of the limit value is as follows:

[0041]

[0042]

[0043]

[0044] wherein IrA, IrB and IrC are the active current limiting values, N1 is the number of units of the energy storage device, N2 is the number of DC modules in the energy storage unit module, nA is the number of bypassed units of phase A, nAi is the number of bypassed DC modules of unit i of phase A, and IR is the rated current value of the energy storage device. In addition, the output voltage capability of the AC side is considered, and in order to ensure that the modulation degree of the system control is not affected after bypassing the unit, the control system also corrects the target value of the unit capacitor C1 voltage. The correction algorithm is as follows:

[0045] Vdc_refA = (N1 / (N1-nA))*Vdc_ref;

[0046] Vdc_refB = (N1 / (N1-nB))*Vdc_ref;

[0047] Vdc_refC = (N1 / (N1-nB))*Vdc_ref;

[0048] wherein Vdc_ref is the initial capacitor voltage setting value, Vdc_refA is the corrected target value of the capacitor voltage of phase A, Vdc_refB is the corrected target value of the capacitor voltage of phase B, and Vdc_refC is the corrected target value of the capacitor voltage of phase C;

[0049] The above is the calculation of the star-connected energy storage device. If the energy storage device is delta-connected, the three-phase identifiers A, B and C in the above formula correspond to AB, BC and CA.

[0050] Further, the unit redundancy control disconnects the faulty DC module or battery pack, while calculating the maximum active output capability on the AC side, ensuring the balance of AC and DC energy flow within the energy storage device, and ensuring that the energy storage device retains its maximum output capability after module bypass.

[0051] Further, the unit redundancy control includes the following method:

[0052] When a DC module in the energy storage unit module fails, the unit can be disconnected from the faulty battery pack by tripping the DC circuit breaker K11...K1n, while locking the corresponding DC converter T11...T1n. At this time, due to the reduction of DC converter modules in the unit, the active energy that the unit can output also decreases accordingly. Therefore, the control command VmodA1...VmodCn needs to be corrected to ensure the balance of AC and DC energy within the unit, and to avoid loss of control due to unbalanced AC and DC energy, causing the energy storage device to shut down.

[0053] The modulation wave command correction calculation method is:

[0054] If (IdcFbkAi<=Idc_Rate), the modulation wave command does not need to be corrected.

[0055] If (IdcFbkAi>Idc_Rate), then VmodAi=VmodAi*KAi

[0056]

[0057] Where VmodAi is the corrected modulation wave, IdcFbkAi is the A-phase i-number unit DC side feedback current, Idc_Rate is the DC current rated value. Kp is the PI control gain parameter, Ki is the PI control integral parameter.

[0058] The above formula is the correction calculation of the A-phase modulation wave. The B-phase and C-phase calculations are the same as the A-phase, and the A in the identifier is replaced by B and C.

[0059] Furthermore, the DC control portion comprises a voltage loop, a current loop, PWM control, and intra-unit battery pack SOC balance control. The voltage loop employs PI control, and the current loop employs PIR control. PI control is performed by comparing the DC voltage reference UdcRef with the unit voltage feedback UdcFbkAi, outputting a unit DC current command IdcRefAi. After intra-unit battery pack SOC balance control, a DC current command IdcRefAij is calculated for each DC converter module within the unit, where i = 1…N1, j = 1…N2, where N1 is the number of phase units of the energy storage device, i.e., the number of novel energy storage converter modules, and N2 is the number of DC converter modules within the energy storage unit module. The current is then calculated through the current loop PIR, where PI in PIR represents a PI controller, R represents a multi-resonant central controller, and PIR is a PI controller with a multi-resonant central controller added. The current can be designed based on the harmonic frequency to be suppressed. Finally, a DC converter modulation wave is calculated, and a control pulse is calculated through PWM control, which is then sent to the DC converter module to control the output command current.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] 1) The novel energy storage device of the present invention is based on a cascade topology and incorporates a DC converter. Its advantages include high voltage direct connection, no need for a step-up transformer, and high overall energy conversion efficiency. It has a multi-level redundant design and high safety. A single unit has large capacity, eliminating the need for parallel coordination of multiple units and resulting in high stability.

[0062] 3) The novel full-bridge energy storage unit module used in the present invention has DC control capability and can effectively suppress DC side harmonics and increase the service life of the battery pack through control algorithm design. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a topological diagram of the delta connection of the novel energy storage device of the present invention;

[0064] Figure 2 This is a star-connected topology diagram of the novel energy storage device of the present invention;

[0065] Figure 3 This is a topological diagram of the new full-bridge energy storage unit module of the present invention;

[0066] Figure 4 This is a block diagram of the AC control system of the delta-connected structure of the novel energy storage device of the present invention;

[0067] Figure 5 This is a block diagram of the star-connected AC control system of the novel energy storage device of the present invention;

[0068] Figure 6 This is a block diagram of the redundancy control of the novel energy storage device system of the present invention;

[0069] Figure 7 is a novel energy storage device unit redundancy control block diagram of the application;

[0070] Figure 8 is a novel energy storage device DC control system block diagram of the application. DETAILED DESCRIPTION

[0071] The specific embodiments of the application are described in detail below with reference to the accompanying drawings.

[0072] As shown in Figures 1-2 , a novel energy storage device, the novel energy storage device is a chain type cascade multilevel structure, comprising a plurality of novel energy storage converter modules (corner structure: PAB1...PABn, PBC1...PBCn, PAC1...PCAn, star structure: PA1...PAn, PB1...PBn, PC1...PCn), a plurality of novel energy storage converter modules are connected in series in turn to form a single-channel cascade type multilevel energy storage structure, and three single-channel cascade type multilevel energy storage structures are connected in star or corner type to form a star structure or a corner structure of the novel energy storage device. The novel energy storage device cascade structure is also connected in series with a main circuit breaker K1, a charging resistor R and a filter reactor L, and also has a bypass circuit breaker K2 connected in parallel across the charging resistor R.

[0073] As shown in Figure 3 , the novel energy storage converter module includes a full-bridge converter module and a DC converter module, and one or more DC converter modules are connected in parallel at the DC side capacitor C1 end of the full-bridge converter module, and the output end of each DC converter module is connected with a battery pack. The DC converter module is a DC chopper circuit structure, and the output end is also connected with a filter reactor L11...L1n and a filter capacitor C11...C1n, and further includes a DC circuit breaker K11...K1n, and the output end of the DC converter module is connected with a battery pack Bat11, Bat1n through the DC circuit breaker K11...K1n. The input end of the full-bridge converter module is also provided with a bypass switch CB1.

[0074] A control method of a novel energy storage device, the control method of the novel energy storage device comprises:

[0075] 1) The main circuit breaker K1 is closed, the full-bridge capacitor C1 of the energy storage device is charged through the charging resistor R, after the charging is completed, K2 is closed, and the charging resistor R is bypassed, at this time, the device full-bridge converter module is unlocked, the equipment has inductive and capacitive idle operation mode, and can exchange reactive power with the system;

[0076] 2) By unlocking the DC converter module, the filter capacitor C11...C1n can be charged to be close to the battery voltage (deviation less than 5V), at this time, the battery Bat11, Bat1n is accessed by closing the DC circuit breaker K11, K1n, at this time, the device has four quadrant operation capability, and can output any active and reactive power within the rated capacity;

[0077] 3) The DC converter module is a chopper circuit structure, and the output DC voltage is adjusted by adjusting the duty cycle of the IGBT switch of the DC converter module, so as to control the current flowing into the battery pack;

[0078] The control method of the new energy storage device comprises an AC control part and a DC control part.

[0079] As shown in Figures 4-5 The AC control part comprises a phase-locked loop, a voltage loop, a current loop, SWPM control, system redundancy control, unit redundancy control, and phase-to-phase SOC balance control; the control target is the AC side output current Iab, Icb, Ica, and the control comprises the following steps:

[0080] Step 1: first, the frequency f = 2π / ω and the phase θ of the system voltage are calculated by the phase-locked loop, and the three-phase voltage (Uab, Ubc, Uca in angular connection, Ua, Ub, Uc in star connection) and the three-phase current (Iab, Ibc, Ica in angular connection, Ia, Ib, Ic in star connection) are converted into Ug_d, Ug_q in DQ coordinate system by the voltage frequency and phase;

[0081] Step 2: the reactor voltage drop UL_d, UL_q is calculated by the current loop according to the active instruction current Id_ref and the reactive instruction current Iq_ref;

[0082] Step 3: the system voltage feedforward Ug_d, Ug_q is added to the reactor voltage drop UL_d, UL_q, and then the park conversion is performed to calculate the three-phase total modulation wave VmodAB, VmodBC, VmodCA or VmodA, VmodB, VmodC;

[0083] Step 4: finally, the three-phase modulation wave is calculated by SPWM to obtain the pulse control instruction required for controlling the IGBT;

[0084] The above variables are described as follows:

[0085] f: system voltage frequency;

[0086] ω: system voltage angular frequency;

[0087] θ: system phase;

[0088] Ug_d: System active voltage in DQ coordinate system;

[0089] Ug_q: System reactive voltage in DQ coordinate system;

[0090] Id_Fbk: System active current in DQ coordinate system;

[0091] Iq_Fbk: System reactive current in DQ coordinate system;

[0092] Id_ref: Active instruction current;

[0093] Iq_ref: Reactive instruction current;

[0094] UL_d: Active voltage of filter reactor L;

[0095] UL_q: Reactive voltage of filter reactor L;

[0096] Ug_d: System active voltage feedforward;

[0097] Ug_q: System reactive voltage feedforward;

[0098] VmodAB, VmodBC, VmodCA: Three-phase total modulation wave when connected in delta;

[0099] VmodA, VmodB, VmodC: Three-phase total modulation wave when connected in star;

[0100] Iab, Icb, Ica are AC side output currents, and are denoted as Ia, Ib, Ic when connected in star.

[0101] The system redundancy control bypasses the faulty energy storage unit module, calculates the active maximum output capability of the energy storage device after the unit is bypassed, performs instruction limiting to avoid overcurrent of the battery current in the energy storage device, and calculates the capacitor C1 voltage instruction value UdcRef to ensure that the modulation degree of the energy storage device after the unit is bypassed is unchanged.

[0102] As shown in Figure 6 The system redundancy control includes the following methods:

[0103] When the faulty unit is bypassed, the system redundancy control calculates the active current output capability of the phase after the bypass according to the number and position of the bypassed units, and limits the active instruction Id_ref of the phase. The calculation method of the limit value is as follows:

[0104]

[0105]

[0106]

[0107] wherein IrA, IrB, IrC are the active current limiting value, N1 is the number of each phase unit of the energy storage device, N2 is the number of DC module in the energy storage unit module, nA is the number of bypass unit of phase A, nAi is the number of bypass of DC module of phase A i unit, IR is the rated current value of the energy storage device. At the same time, considering the output voltage capacity of the AC side, in order to ensure that the regulation degree of the system control is not affected after the unit bypass, the control system also corrects the voltage target value of the unit capacitor C1, and the correction algorithm is:

[0108] Vdc_refA=(N1 / (N1-nA))*Vdc_ref;

[0109] Vdc_refB=(N1 / (N1-nB))*Vdc_ref;

[0110] Vdc_refC=(N1 / (N1-nB))*Vdc_ref;

[0111] wherein Vdc_ref is the initial capacitor voltage setting value, Vdc_refA is the corrected A phase capacitor voltage target value, Vdc_refB is the corrected B phase capacitor voltage target value, and Vdc_refC is the corrected C phase capacitor voltage target value;

[0112] The above is the calculation of the star-connected energy storage device. If the energy storage device is delta-connected, the three-phase identifiers A, B, and C in the above formula correspond to AB, BC, and CA.

[0113] The unit redundancy control disconnects the faulty DC module or battery pack, calculates the maximum active output power on the AC side, ensures the balance of AC and DC energy flow in the energy storage device, and ensures that the energy storage device retains its maximum output capacity after the module bypass.

[0114] As shown in Figure 7 The unit redundancy control includes the following methods:

[0115] When a DC module in the energy storage unit module fails, the unit can be disconnected from the faulty battery pack by tripping the DC circuit breaker K11...K1n, and the corresponding DC converter T11...T1n is locked out. At this time, due to the reduction of DC converter modules in the unit, the active energy output by the unit is also reduced accordingly. Therefore, the control instruction VmodA1...VmodCn needs to be corrected to ensure the balance of AC and DC energy in the unit, and to avoid loss of control due to imbalance of AC and DC energy, causing the energy storage device to fail.

[0116] The modulation wave instruction correction calculation method is:

[0117] If (IdcFbkAi <= Idc_Rate), the modulation wave instruction does not need to be corrected;

[0118] If (IdcFbkAi > Idc_Rate), VmodAi = VmodAi * KAi

[0119]

[0120] Wherein VmodAi is the corrected modulation wave, IdcFbkAi is the A-phase i-number unit DC side feedback current, Idc_Rate is the DC current rated value. Kp is the PI control gain parameter, Ki is the PI control integral parameter;

[0121] The above formula is the correction calculation of the A-phase modulation wave, and the B-phase and C-phase calculations are the same as the A-phase, and A in the identification is replaced by B and C.

[0122] The inter-phase SOC balance control is prior art, which will not be described in detail here.

[0123] As shown in Figure 8 The DC control part is composed of a voltage loop, a current loop, a PWM control, and an intra-unit battery pack SOC balance control, wherein the voltage loop adopts PI control, the current loop adopts PIR control, PI control is performed through comparison of the DC voltage given UdcRef and the unit voltage feedback UdcFbkAi, and the unit DC current instruction IdcRefAi is output, the intra-unit battery pack SOC balance control is performed to calculate the DC current instructions IdcRefAij of the intra-unit DC converter modules, i = 1 …… N1, j = 1 …… N2, N1 is the number of each phase unit of the energy storage device, i.e. the number of the novel energy storage converter modules, and N2 is the number of the intra-unit DC converter modules of the energy storage unit; PIR calculation is performed again, wherein PI in PIR is a PI controller, R is a multi-resonance center controller, and PIR is a multi-resonance center controller added on the basis of the PI controller; the harmonic frequency to be suppressed can be designed according to the requirement, and finally the DC converter modulation wave is calculated, the control pulse is calculated through PWM control, and the control output instruction current is output to the DC converter module.

[0124] The above embodiments are implemented on the premise of the technical scheme of the present application, detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the above embodiments. The methods used in the above embodiments are all conventional methods unless otherwise specified.

Claims

1. A control method of a novel energy storage device, characterized by, The new energy storage device is a chain type cascade multi-level structure, comprising a plurality of new energy storage converter modules, the plurality of new energy storage converter modules are sequentially connected in series to form a single-path cascade multi-level energy storage structure, and three single-path cascade multi-level energy storage structures are connected in star or delta to form a new energy storage device in star or delta structure; The new energy storage converter module comprises a full-bridge converter module and a direct-current converter module, one or more direct-current converter modules are connected in parallel at the capacitor C1 end of the direct-current side of the full-bridge converter module, and the output end of each direct-current converter module is connected with a battery pack; The control method of the new energy storage device comprises an alternating current control part and a direct current control part; The alternating current control part comprises a phase-locked loop, a voltage loop, a current loop, SWPM control, system redundancy control, unit redundancy control and phase-to-phase SOC balance control; the control target is alternating current side output current Iab, Icb and Ica, and the control comprises the following steps: Step 1, the frequency f = 2π / ω and the phase θ of the system voltage are calculated through the phase-locked loop, and the system three-phase voltage and three-phase current are converted into Ug_d and Ug_q in the DQ coordinate system through the voltage frequency and phase; Step 2, the reactor voltage drop UL_d and UL_q are calculated according to the active instruction current Id_ref and the reactive instruction current Iq_ref through the current loop; Step 3, the system voltage feedforward Ug_d and Ug_q are added to the reactor voltage drop UL_d and UL_q, and then the three-phase total modulation wave VmodAB, VmodBC and VmodCA or VmodA, VmodB and VmodC are calculated through park transformation; Step 4, finally, the pulse control instruction required for controlling the IGBT is calculated through SPWM from the three-phase modulation wave; The above variables are described as follows: f: system voltage frequency; ω: system voltage angular frequency; θ: system phase; Ug_d: system active voltage in the DQ coordinate system; Ug_q: system reactive voltage in the DQ coordinate system; Id_Fbk: system active current in the DQ coordinate system; Iq_Fbk: system reactive current in the DQ coordinate system; Id_ref: active instruction current; Iq_ref: reactive instruction current; UL_d: active voltage of the filter reactor L; UL_q: reactive voltage of the filter reactor L; Ug_d: system active voltage feedforward; Ug_q: system reactive voltage feedforward; VmodAB, VmodBC, VmodCA: three-phase total modulation wave when connected in delta; VmodA, VmodB, VmodC: three-phase total modulation wave when connected in star; Iab, Icb, Ica are alternating current side output currents, and are denoted as Ia, Ib and Ic when connected in star; The system redundancy control bypasses the faulty energy storage unit module, calculates the maximum active output capacity of the energy storage device after the unit is bypassed, limits the instruction, avoids the overcurrent of the battery current in the energy storage device, calculates the capacitor C1 voltage instruction value UdcRef, and ensures that the modulation degree of the energy storage device does not change after the unit is bypassed. The system redundancy control includes the following method: When the faulty unit is bypassed, the system redundancy control calculates the active current output capability of the phase after bypassing according to the number and position of the bypassed units, and limits the active current instruction Id_ref of the phase, the limit value ; ； ； Wherein, IrA, IrB, IrC are the active current limiting values, N1 is the number of each phase unit of the energy storage device, N2 is the number of DC modules in the energy storage unit module, nA is the number of A-phase bypass units, nAi is the number of bypasses of the DC module of the A-phase i unit, IR is the rated current value of the energy storage device; considering the output voltage capacity of the AC side, in order to not affect the regulation degree of the system control after the unit bypass, the control system also corrects the unit capacitor C1 voltage target value, and the correction algorithm is: Vdc_refA = (N1 / (N1-nA))*Vdc_ref; Vdc_refB = (N1 / (N1-nB))*Vdc_ref; Vdc_refC = (N1 / (N1-nB))*Vdc_ref; Wherein, Vdc_ref is the initial capacitor voltage setting value, Vdc_refA is the corrected A-phase capacitor voltage target value, Vdc_refB is the corrected B-phase capacitor voltage target value, and Vdc_refC is the corrected C-phase capacitor voltage target value; The above is the calculation of the star-connected energy storage device, and if the energy storage device is delta-connected, the three-phase identifiers A, B, and C in the above formula correspond to AB, BC, and CA.

2. The control method of a new energy storage device according to claim 1, characterized by, The DC converter module is a DC chopper circuit structure, and the output end is further connected with filter reactors L11...L1n and filter capacitors C11...C1n, and further includes DC breakers K11...K1n, and the output end of the DC converter module is connected with battery groups Bat11, Bat1n through the DC breakers K11...K1n; The input end of the full-bridge converter module is further provided with a bypass switch CB1.

3. The method of claim 1, wherein the method is a method of controlling a new energy storage device. The new energy storage device cascade structure is further connected in series with a main breaker K1, a charging resistor R, and a filter reactor L, and further has a bypass breaker K2 connected in parallel across the charging resistor R.

4. The control method of a new energy storage device according to any one of claims 1 to 3, characterized by, The control method of the new energy storage device includes: 1) The main breaker K1 is closed, the DC side capacitor C1 of the full-bridge converter module of the energy storage device is charged through the charging resistor R, after the charging is completed, K2 is closed, and the charging resistor R is bypassed, at this time, the full-bridge converter module of the device is unlocked, the device has inductive and capacitive reactive power operation modes, and can exchange reactive power with the system; 2) By unlocking the DC converter module, the filter capacitors C11...C1n can be charged to a voltage deviation of less than 5V from the battery group voltage, at this time, the battery groups Bat11, Bat1n are connected by closing the DC breakers K11, K1n, at this time, the device has four-quadrant operation capability, and can output any active and reactive power within the rated capacity; 3) The DC converter module is a chopper circuit structure, the output DC voltage is adjusted by adjusting the duty cycle of the IGBT switch of the DC converter module, and then the target of controlling the current flowing into the battery group is achieved; The control method of the new energy storage device includes an AC control part and a DC control part.

5. The method of claim 1, wherein the method is a method of controlling a new energy storage device. The unit redundancy control disconnects the faulty DC module or battery pack, calculates the maximum active output capacity on the AC side, ensures the balance of AC and DC energy flow in the energy storage device, and ensures that the energy storage device retains its maximum output capacity after bypassing the module.

6. The control method of a novel energy storage device according to claim 5, wherein The unit redundancy control comprises the following method: When a DC module in the energy storage unit module fails, the unit can be disconnected from the faulty battery pack by tripping the DC circuit breaker K11...K1n, and the corresponding DC converter T11...T1n is locked out. At this time, due to the reduction of the DC converter module in the unit, the active energy output by the unit also decreases accordingly. Therefore, the control instruction VmodA1...VmodCn needs to be corrected to ensure the balance of AC and DC energy inside the unit and avoid loss of control due to unbalanced AC and DC energy, causing the energy storage device to fail. The modulation wave instruction correction calculation method is as follows: If (IdcFbkAi <=Idc_Rate), the modulation wave instruction does not need to be corrected. If (IdcFbkAi >Idc_Rate), VmodAi = VmodAi*KAi; KAl = 1 - (Idc_FbkAl - Idc_Rate) * Kp- *Ki; Where VmodAi is the corrected modulation wave, IdcFbkAi is the A-phase i-unit DC side feedback current, Idc_Rate is the DC current rating, Kp is the PI control gain parameter, and Ki is the PI control integral parameter. The above formula is the correction calculation of the A-phase modulation wave, and the B-phase and C-phase calculations are the same as the A-phase, with A replaced by B and C in the identification.

7. The method of claim 1, wherein the method is a method of controlling a new energy storage device. The DC control part is composed of a voltage loop, a current loop, a PWM control, and a battery pack SOC balance control inside the unit. The voltage loop adopts PI control, and the current loop adopts PIR control. The DC voltage given UdcRef is compared with the unit voltage feedback UdcFbkAi to perform PI control, and the unit DC current instruction IdcRefAi is output. After the battery pack SOC balance control inside the unit, the DC current instruction IdcRefAij of each DC converter module inside the unit is calculated, i=1...N1, j=1...N2, N1 is the number of energy storage device units, i.e. the number of new energy storage converter modules, and N2 is the number of DC converter modules inside the energy storage unit module. Then, the PIR calculation is performed, where PI is a PI controller and R is a multi-resonant center controller. PIR is a multi-resonant center controller added to the PI controller. The harmonic frequency to be suppressed can be designed, and finally the DC converter modulation wave is calculated. The PWM control calculates the control pulse, which is sent to the DC converter module for control output instruction current.

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