A hybrid energy storage control method and device based on a dead-time compensation T-type three-level inverter

Abstract

The application discloses a kind of based on dead zone compensation T type three-level inverter hybrid energy storage control method and device, belong to hybrid energy storage control technical field, hybrid energy storage includes lithium battery and super capacitor, respectively through bidirectional DC / DC charge-discharge circuit connection to the DC side of T type three-level inverter, its AC side is connected to large power grid;Control method includes: judging whether T type three-level inverter is in dead zone, if in dead zone, then the compensation energy needed by super capacitor is compensated quickly to dead zone;It is judged whether active power is short on large power grid side, if short, then unbalanced power is decomposed by frequency band, high-frequency component is compensated quickly by super capacitor, low-frequency component is compensated quickly by lithium battery;After quick compensation, according to the state of charge of lithium battery and super capacitor, its output power is secondly corrected.The application can carry out dead zone compensation and frequency band power distribution, improve the efficiency and life of hybrid energy storage.

Description

Technical Field

[0001] This invention relates to the field of hybrid energy storage control technology, and in particular to a hybrid energy storage control method and device based on a dead-zone compensated T-type three-level inverter. Background Technology

[0002] With the increasing penetration rate of new energy sources, the power system faces challenges such as declining inertia and increased frequency fluctuations. The coordinated control of hybrid energy storage systems (HESS) and power electronic converters has become a key technology for improving the grid connection stability of wind power.

[0003] The power storage converter (PCS) is a core component of a power energy storage system. The topology and control strategy of the PCS significantly impact grid connection performance. Traditional two-level converter-based solutions are no longer suitable for high-proportion new energy power systems with large-scale energy storage. For large-capacity PCS topologies, distributed configuration schemes based on multi-level (three-level and above) converters are the preferred solution for achieving medium-voltage, large-capacity AC-DC power conversion. Multi-level (three-level and above) converters have switching delays in their power devices. If a device in the same bridge arm needs to be turned off but is not, and its complementary device turns on, shoot-through will occur, burning out the device. To prevent inverter shoot-through, a dead time needs to be added to the complementary trigger signals. To mitigate the impact of the dead time effect on the system, dead time compensation is required. Traditional dead time compensation methods use fixed-time compensation, failing to consider current zero-crossing regions and complex sector switching conditions, leading to compensation failure and even waveform quality degradation. Near the zero-crossing current, the voltage error caused by the dead time is strongly coupled with the current direction, and fixed compensation cannot adapt dynamically, leading to an increase in low-frequency harmonic content. At the same time, the static power distribution of traditional hybrid energy storage causes lithium batteries to frequently respond to high-frequency disturbances, reducing the service life of lithium battery energy storage. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hybrid energy storage control method and device based on a dead-zone compensation T-type three-level inverter, so as to solve the technical problems of dead-zone compensation and power distribution in hybrid energy storage systems based on multi-level (three-level and above) converters.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] In a first aspect, the present invention provides a hybrid energy storage control method based on a dead-zone compensated T-type three-level inverter, wherein the hybrid energy storage includes a lithium battery and a supercapacitor, the lithium battery and the supercapacitor being connected to the DC side of the T-type three-level inverter via bidirectional DC / DC charging and discharging circuits, and the AC side of the T-type three-level inverter being connected to the mains power grid; the control method includes:

[0007] Determine whether the T-type three-level inverter is in the dead zone. If it is in the dead zone, quickly compensate for the energy required for the dead zone through the supercapacitor, and compensate for the energy of the supercapacitor through the lithium battery.

[0008] Determine whether there is a shortage of active power on the main grid side. If there is a shortage, decompose the unbalanced power into frequency bands, and use the supercapacitor to quickly compensate for the high-frequency components and the lithium battery to quickly compensate for the low-frequency components.

[0009] After rapid compensation, the output power is corrected a second time based on the state of charge of the lithium battery and the supercapacitor.

[0010] Secondly, the present invention provides a hybrid energy storage control device based on a dead-zone compensated T-type three-level inverter. The hybrid energy storage includes a lithium battery and a supercapacitor. The lithium battery and the supercapacitor are respectively connected to the DC side of the T-type three-level inverter via a bidirectional DC / DC charging / discharging circuit. The AC side of the T-type three-level inverter is connected to the mains power grid. The control device includes:

[0011] The dead zone detection module is configured to determine whether the T-type three-level inverter is in a dead zone. If it is in a dead zone, the supercapacitor is used to quickly compensate for the energy required to compensate for the dead zone, and the lithium battery is used to compensate for the energy of the supercapacitor.

[0012] The deficit judgment module is configured to determine whether there is a deficit in active power on the grid side. If there is a deficit, the unbalanced power is decomposed into frequency bands, and the high-frequency component is quickly compensated by the supercapacitor and the low-frequency component is quickly compensated by the lithium battery.

[0013] The secondary correction module is configured to perform a secondary correction on the output power of the lithium battery and the supercapacitor based on their state of charge after rapid compensation.

[0014] Thirdly, the present invention provides an electronic device, including a processor and a storage medium;

[0015] The storage medium is used to store instructions;

[0016] The processor is configured to operate according to the instructions to perform the steps according to the method described above.

[0017] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0018] Fifthly, the present invention provides a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of the above-described method.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0020] This invention provides a hybrid energy storage control method and device based on a dead-zone compensated T-type three-level inverter. By combining dynamic dead-zone compensation with direct connection to the energy storage neutral point, it effectively suppresses voltage waveform distortion and significantly improves harmonic suppression capability. Furthermore, compared to traditional two-level inverters with high switching losses and low system efficiency, this invention effectively improves system efficiency. Simultaneously, traditional hybrid energy storage static power distribution causes lithium batteries to frequently respond to high-frequency disturbances, reducing the lithium battery's energy storage lifespan. This invention uses frequency band decomposition technology to isolate high-frequency components, thereby extending the energy storage lifespan. Dead-zone compensation and energy storage control are coordinated; the supercapacitor directly compensates for dead-zone energy through the neutral point, reducing bus voltage fluctuations. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the hybrid energy storage topology provided in an embodiment of the present invention;

[0022] Figure 2 This is a flowchart of the control method for hybrid energy storage provided in an embodiment of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0024] Example 1:

[0025] This invention provides a hybrid energy storage control method based on a dead-time compensated T-type three-level inverter, such as... Figure 1 As shown, the hybrid energy storage includes lithium batteries and supercapacitors. The lithium batteries and supercapacitors are connected to the DC side of a T-type three-level inverter through bidirectional DC / DC charging and discharging circuits, and the AC side of the T-type three-level inverter is connected to the main power grid.

[0026] like Figure 2 As shown, the control methods include:

[0027] (1) Determine whether the T-type three-level inverter is in the dead zone. If it is in the dead zone, the supercapacitor is used to quickly compensate for the energy required for the dead zone, and the lithium battery is used to compensate for the energy of the supercapacitor.

[0028] While eliminating output voltage distortion, the dead-zone compensation method generates a high-frequency pulsating compensation power demand on the DC bus side. This high-frequency pulsating compensation power is quickly compensated by the supercapacitor.

[0029] Dead-time compensation for a T-type three-level inverter includes:

[0030] Obtain the AC side current of the T-type three-level inverter , Indicates three-phase alternation;

[0031] AC side current The reference current is obtained by filtering through a filter. The filter cutoff frequency is set to 0.5 times the switching frequency;

[0032] When the reference current less than the switching threshold current Implement the dead zone compensation plan;

[0033] When the load inductive reactance is significantly less than the load impedance, the AC side voltage and current of the T-type three-level inverter are approximately synchronized; when When the phase current crosses zero, the phase of the AC side voltage is about 90°. The modulation coefficient is set to 0.85 so that the reference voltage is located in the second major sector and the fourth minor sector, corresponding to the switching sequence NON-NPN-OPN-OPO-OPN-NPN-NON.

[0034] like If the dead zone elimination strategy fails, a dead zone needs to be inserted and compensated during the NPN→OPN handover process.

[0035] when During the NPN→OPN switch, the duration of NPN operation is increased. OPN duration - The OPN→NPN switch has no impact.

[0036] when During the initial NPN to OPN transition, there is no impact; during the OPN to NPN transition, the OPN duration is increased. NPN duration - ;

[0037] Based on the above mechanism, the algebraic relationship of the compensation amount can be expressed as follows:

[0038]

[0039] in, For the switching cycle, Dead time, It is a symbolic function; These are the values ​​before and after the correction for the NPN duration. These are the values ​​before and after the correction for the duration of OPN.

[0040] Dead-time compensation is used to fine-tune the on-time of the switching transistor and synthesize an additional voltage pulse at the output to offset the voltage error caused by the dead-time effect.

[0041] The change in conduction time is The average compensation voltage generated by time compensation for:

[0042]

[0043] Based on the fundamental principles of electric power, if an average compensation voltage is required... Therefore, it is necessary to provide or absorb the corresponding power, and the dead zone requires compensation energy. for:

[0044]

[0045] In the formula, Dead time, For the switching cycle, for AC side of the T-type three-level inverter Phase current, for The reference current, For symbolic functions, This refers to the DC-side voltage of a T-type three-level inverter.

[0046] (2) Determine whether there is a shortage of active power on the grid side. If there is a shortage, decompose the unbalanced power into frequency bands, use supercapacitors to quickly compensate for the high-frequency components, and use lithium batteries to quickly compensate for the low-frequency components.

[0047] When there is an active power deficit on the main power grid side, hybrid energy storage is needed to compensate for the unbalanced power. When the power generation is greater than the power consumption, the hybrid energy storage is charged, and vice versa.

[0048] Frequency band decomposition of unbalanced power specifically includes the following steps:

[0049] 1) Random normally distributed white noise is superimposed on the unbalanced power to generate the target signal;

[0050] 2) Perform empirical mode decomposition on the target signal to extract all IMF components;

[0051] 3) Each IMF component is a single-component oscillating signal, denoted as... The transformed signal is obtained through Hilbert transform. ;

[0052] 4) Transform the signal As Construct an analytic signal from the orthogonal imaginary parts of the given information:

[0053]

[0054] In the formula, The imaginary unit, These represent the instantaneous amplitude and instantaneous phase of the signal. , ;

[0055] 5) Based on instantaneous phase Taking the derivative with respect to time yields the instantaneous frequency:

[0056]

[0057] 6) Set the boundary frequency Calculate aliasing energy :

[0058]

[0059] In the formula, The instantaneous frequency of the k-th order IMF component is lower than the boundary frequency. The p-th time period, m is the time period Quantity; The instantaneous frequency of the (k+1)th order IMF component is higher than the boundary frequency. The q-th time period, where n is the number of time periods. Quantity; The duration of each time period;

[0060] 7) Using aliased energy At its minimum, the corresponding boundary frequency The high-frequency unbalanced power component, which is the superposition of IMF components above the high-frequency power boundary point, is taken as the high-frequency component, and the low-frequency unbalanced power component, which is the superposition of IMF components below the high-frequency power boundary point, is taken as the low-frequency component.

[0061] (3) After rapid compensation, the output power is corrected a second time according to the state of charge of the lithium battery and the supercapacitor.

[0062] The output power of the second correction is:

[0063]

[0064] In the formula, The output power before and after the second correction. The current state of charge, The critical values ​​for over-discharge and overcharge. This refers to the critical value that needs to be adjusted for over-expansion and the process.

[0065] Through secondary correction, overcharging and over-discharging of lithium batteries and supercapacitors are avoided, thus ensuring their service life.

[0066] Example 2:

[0067] A hybrid energy storage control device based on a dead-zone compensated T-type three-level inverter, comprising a lithium battery and a supercapacitor, wherein the lithium battery and supercapacitor are connected to the DC side of the T-type three-level inverter via bidirectional DC / DC charging / discharging circuits, and the AC side of the T-type three-level inverter is connected to the mains power grid; the control device includes:

[0068] The dead zone detection module is configured to determine whether the T-type three-level inverter is in the dead zone. If it is in the dead zone, the supercapacitor is used to quickly compensate for the energy required for the dead zone, and the lithium battery is used to compensate for the energy of the supercapacitor.

[0069] The deficit judgment module is configured to determine whether there is a deficit in active power on the grid side. If there is a deficit, the unbalanced power is decomposed into frequency bands, and the high-frequency components are quickly compensated by supercapacitors and the low-frequency components are quickly compensated by lithium batteries.

[0070] The secondary correction module is configured to perform a secondary correction on the output power of the lithium battery and the supercapacitor based on the state of charge of the lithium battery and the supercapacitor after rapid compensation.

[0071] Example 3:

[0072] Based on the hybrid energy storage control method provided in Embodiment 1, the present invention provides an electronic device, including a processor and a storage medium;

[0073] Storage media are used to store instructions;

[0074] The processor is used to perform operations according to instructions to execute the steps according to the method described above.

[0075] Example 4:

[0076] Based on the hybrid energy storage control method provided in Embodiment 1, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above method.

[0077] Example 5:

[0078] Based on the hybrid energy storage control method provided in Embodiment 1, the present invention provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the above method.

[0079] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0080] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0081] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0082] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0083] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hybrid energy storage control method based on a dead-time compensated T-type three-level inverter, characterized in that, The hybrid energy storage includes a lithium battery and a supercapacitor. The lithium battery and the supercapacitor are respectively connected to the DC side of the T-type three-level inverter via a bidirectional DC / DC charging and discharging circuit. The AC side of the T-type three-level inverter is connected to the mains power grid. The control method includes: Determine whether the T-type three-level inverter is in the dead zone. If it is in the dead zone, quickly compensate for the energy required for the dead zone through the supercapacitor, and compensate for the energy of the supercapacitor through the lithium battery. Determine whether there is a shortage of active power on the main grid side. If there is a shortage, decompose the unbalanced power into frequency bands, and use the supercapacitor to quickly compensate for the high-frequency components and the lithium battery to quickly compensate for the low-frequency components. After rapid compensation, the output power is corrected a second time based on the state of charge of the lithium battery and the supercapacitor. The dead-time compensation of the T-type three-level inverter includes: Obtain the AC side current of the T-type three-level inverter , Indicates three-phase alternation; AC side current The reference current is obtained by filtering through a filter. The cutoff frequency of the filter is set to 0.5 times the switching frequency; When the reference current less than the switching threshold current Implement the dead zone compensation plan; When the load inductive reactance is significantly less than the load impedance, the AC side voltage and current of the T-type three-level inverter are approximately synchronized; when When the phase current crosses zero, the phase of the AC side voltage is about 90°. The modulation coefficient is set to 0.85 so that the reference voltage is located in the second major sector and the fourth minor sector, corresponding to the switching sequence NON-NPN-OPN-OPO-OPN-NPN-NON. like If the dead zone elimination strategy fails, a dead zone needs to be inserted and compensated during the NPN→OPN handover process. when During the NPN→OPN switch, the duration of NPN operation is increased. OPN duration - The OPN→NPN switch has no impact. when During the initial NPN to OPN transition, there is no impact; during the OPN to NPN transition, the OPN duration is increased. NPN duration - ; Based on the above mechanism, the algebraic relationship of the compensation amount can be expressed as follows: ； in, For the switching cycle, Dead time, It is a symbolic function; These are the values ​​before and after the correction for the NPN duration. These are the values ​​before and after the correction for the duration of OPN.

2. The hybrid energy storage control method based on a dead-time compensated T-type three-level inverter according to claim 1, characterized in that, The lithium battery is an energy-type energy storage lithium battery, and the supercapacitor is a power-type energy storage supercapacitor.

3. The hybrid energy storage control method based on a dead-time compensated T-type three-level inverter according to claim 1, characterized in that, The dead-time compensation is to fine-tune the on-time of the switching transistor and synthesize an additional voltage pulse at the output to offset the voltage error caused by the dead-time effect. The change in conduction time is The average compensation voltage generated by time compensation for: ； Based on the fundamental principles of electric power, if an average compensation voltage is required... Therefore, the corresponding power must be provided or absorbed, and the compensation energy required for the dead zone must be provided. for: ； In the formula, Dead time, For the switching cycle, for AC side of the T-type three-level inverter Phase current, for The reference current, For symbolic functions, This refers to the DC-side voltage of a T-type three-level inverter.

4. The hybrid energy storage control method based on a dead-time compensated T-type three-level inverter according to claim 1, characterized in that, The frequency band decomposition of unbalanced power includes: Random normally distributed white noise is superimposed on unbalanced power to generate the target signal; Perform empirical mode decomposition on the target signal to extract all IMF components; Each IMF component is a single-component oscillating signal, denoted as... The transformed signal is obtained through Hilbert transform. ; Transform signal As Construct an analytic signal from the orthogonal imaginary parts of the given information: ； In the formula, The imaginary unit, These represent the instantaneous amplitude and instantaneous phase of the signal. , ; Based on instantaneous phase Taking the derivative with respect to time yields the instantaneous frequency: ； Set the boundary frequency Calculate aliasing energy : ； In the formula, The instantaneous frequency of the k-th order IMF component is lower than the boundary frequency. The p-th time period, m is the time period Quantity; The instantaneous frequency of the (k+1)th order IMF component is higher than the boundary frequency. The q-th time period, where n is the number of time periods. Quantity; The duration of each time period; With aliased energy At its minimum, the corresponding boundary frequency The high-frequency unbalanced power component, which is the superposition of IMF components above the high-frequency power boundary point, is taken as the high-frequency component, and the low-frequency unbalanced power component, which is the superposition of IMF components below the high-frequency power boundary point, is taken as the low-frequency component.

5. The hybrid energy storage control method based on a dead-time compensated T-type three-level inverter according to claim 1, characterized in that, The output power of the second correction is: ； In the formula, The output power before and after the second correction. The current state of charge, The critical values ​​for over-discharge and overcharge. This refers to the critical value that needs to be adjusted for over-expansion and the process.

6. A hybrid energy storage control device based on a dead-time compensated T-type three-level inverter, characterized in that, The hybrid energy storage includes a lithium battery and a supercapacitor. The lithium battery and the supercapacitor are respectively connected to the DC side of the T-type three-level inverter via a bidirectional DC / DC charging and discharging circuit. The AC side of the T-type three-level inverter is connected to the mains power grid. The control device includes: The dead zone detection module is configured to determine whether the T-type three-level inverter is in a dead zone. If it is in a dead zone, the supercapacitor is used to quickly compensate for the energy required to compensate for the dead zone, and the lithium battery is used to compensate for the energy of the supercapacitor. The deficit judgment module is configured to determine whether there is a deficit in active power on the grid side. If there is a deficit, the unbalanced power is decomposed into frequency bands, and the high-frequency component is quickly compensated by the supercapacitor and the low-frequency component is quickly compensated by the lithium battery. The secondary correction module is configured to perform a secondary correction on the output power based on the state of charge of the lithium battery and the supercapacitor after rapid compensation. The dead-time compensation of the T-type three-level inverter includes: Obtain the AC side current of the T-type three-level inverter , Indicates three-phase alternation; AC side current The reference current is obtained by filtering through a filter. The cutoff frequency of the filter is set to 0.5 times the switching frequency; When the reference current less than the switching threshold current Implement the dead zone compensation plan; When the load inductive reactance is significantly less than the load impedance, the AC side voltage and current of the T-type three-level inverter are approximately synchronized; when When the phase current crosses zero, the phase of the AC side voltage is about 90°. The modulation coefficient is set to 0.85 so that the reference voltage is located in the second major sector and the fourth minor sector, corresponding to the switching sequence NON-NPN-OPN-OPO-OPN-NPN-NON. like If the dead zone elimination strategy fails, a dead zone needs to be inserted and compensated during the NPN→OPN handover process. when During the NPN→OPN switch, the duration of NPN operation is increased. OPN duration - The OPN→NPN switch has no impact. when During the initial NPN to OPN transition, there is no impact; during the OPN to NPN transition, the OPN duration is increased. NPN duration - ; Based on the above mechanism, the algebraic relationship of the compensation amount can be expressed as follows: ； in, For the switching cycle, Dead time, It is a symbolic function; These are the values ​​before and after the correction for the NPN duration. These are the values ​​before and after the correction for the duration of OPN.

7. An electronic device, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1-5.

9. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method described in any one of claims 1-5.

Images