Battery energy storage system based on charging cycle monitoring

Abstract

The invention discloses a battery energy storage system based on charging cycle monitoring. A battery module is connected in series with a DC-DC converter module I and is connected to a DC bus; the super capacitor module is connected in series with the DC-DC converter module 2 and is connected to the DC bus. The first DC-DC converter module and the second DC-DC converter module are both in signal connection with the converter control management layer. The converter control management layer is in signal connection with the energy control management layer; the battery module and the super capacitor module are in signal connection with the energy control management layer; a power distribution control strategy is arranged in the energy control management layer and used for coordinating energy distribution between the battery module and the super-capacitor module. According to the invention, the response speed of the system to the transient load is improved, and the reliability of the system is improved; energy flow between the battery module and the super capacitor module is optimized, and the use efficiency of energy is improved; and the deep discharging and charging period of the battery module is effectively reduced, the working load is reduced, and the overall service life of the system is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage and management, and particularly to a battery energy storage system based on charging cycle monitoring. Background Art

[0002] Energy storage technology mainly refers to the storage of electrical energy. The stored energy can be used as emergency energy, or for energy storage when the grid load is low and output energy when the grid load is high, for peak shaving and valley filling to reduce grid fluctuations.

[0003] Battery energy storage systems have become key technical solutions in modern power systems due to their high-efficiency energy storage, flexible power output, and excellent renewable energy integration capabilities. Among existing battery energy storage systems, there is a hybrid energy storage system that integrates two or more energy storage units and can leverage the technical advantages of multiple energy storage units. However, in response to system voltage fluctuations caused by sudden addition and removal of high-frequency loads in the grid, the power distribution strategies of existing hybrid energy storage systems cannot fully utilize the advantages of various energy storage units, resulting in the state of charge of the energy storage units breaking through the upper and lower limits, shortening the service life of the energy storage units, and there is also a safety hazard of breaking down the energy storage units. Therefore, there is an urgent need for a power distribution control strategy for a hybrid energy storage system that can respond quickly and handle large voltage fluctuations.

[0004] In view of this, we propose a battery energy storage system based on charging cycle monitoring. Summary of the Invention

[0005] The purpose of the present invention is to provide a battery energy storage system based on charging cycle monitoring to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A battery energy storage system based on charging cycle monitoring, the battery energy storage system includes: a battery module, a supercapacitor module, an energy control management layer, a converter control management layer, a DC-DC converter module one, and a DC-DC converter module two;

[0007] The battery module is connected in series with the DC-DC converter module one and connected to the DC bus;

[0008] The supercapacitor module is connected in series with the DC-DC converter module two and connected to the DC bus;

[0009] Both the DC-DC converter module one and the DC-DC converter module two are signal-connected to the converter control management layer;

[0010] The converter control management layer is signal-connected to the energy control management layer;

[0011] Both the battery module and the supercapacitor module are signal-connected to the energy control management layer;

[0012] The power distribution control strategy is set inside the energy control management layer. The power distribution control strategy includes a virtual impedance control strategy for adjusting the parameters of the first DC-DC converter module and the second DC-DC converter module, and a transient response control strategy for adjusting the parameters of the second DC-DC converter module. The power distribution control strategy controls the energy distribution between the battery module and the supercapacitor module through the converter control management layer, the first DC-DC converter module, and the second DC-DC converter module.

[0013] Preferably, the battery module includes a battery management system and a battery. The battery management system is used to monitor the voltage, temperature, and charge and discharge status of the battery.

[0014] Preferably, the supercapacitor module includes a supercapacitor management system and a supercapacitor. The supercapacitor management system is used to monitor the voltage and temperature of the supercapacitor.

[0015] Preferably, the energy control management layer includes a data acquisition unit. The data acquisition unit is used to collect the following information A:

[0016] The state of charge, maximum available power, voltage, and current of the battery module;

[0017] The maximum available power, voltage, and current of the supercapacitor module;

[0018] The filter inductance and voltage of the DC bus.

[0019] Preferably, the power distribution control strategy sends a duty cycle control instruction and a frequency control instruction to the converter control management layer. The converter control management layer adjusts the duty cycle and frequency of the pulses of the first DC-DC converter module and the second DC-DC converter module according to the above instructions, so as to adjust the power value and current value of the battery module through the first DC-DC converter module, and adjust the current value of the supercapacitor module through the second DC-DC converter module.

[0020] Preferably, the energy control management layer includes an arithmetic logic unit. The arithmetic logic unit is used to judge whether the DC bus voltage has a sudden rise or fall, as follows:

[0021] When the DC bus voltage does not have a sudden rise or fall, it is determined to be normal;

[0022] At this time, the power distribution control strategy sends a first compensation instruction or a standby instruction acting on the supercapacitor module to the converter control management layer;

[0023] When the DC bus voltage has a sudden rise or fall and the power to be compensated on the DC bus does not exceed the power threshold of the supercapacitor module, it is determined to be abnormal state one;

[0024] At this time, the transient response control strategy sends a compensation instruction 2 acting on the DC-DC converter module 2 to the converter control management layer to adjust the duty cycle and frequency of the DC-DC converter module 2;

[0025] When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated exceeds the power threshold of the supercapacitor module, it is determined to be abnormal state 2;

[0026] At this time, the virtual impedance control strategy sends compensation instruction three to the converter control management layer, which acts on DC-DC converter module one and DC-DC converter module two at the same time to adjust the duty cycle and frequency of DC-DC converter module one and DC-DC converter module two.

[0027] Preferably, the execution process of the power allocation control strategy includes the following steps:

[0028] S1, the data acquisition unit obtains information A;

[0029] S2, the arithmetic logic unit determines whether the DC bus voltage suddenly rises or drops:

[0030] When the DC bus voltage does not suddenly rise or fall, it is judged as normal and enters S3;

[0031] When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated does not exceed the power threshold of the supercapacitor module, it is determined to be abnormal state 1 and enters S4;

[0032] When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated exceeds the power threshold of the supercapacitor module, it is determined as abnormal state 2 and enters S5;

[0033] S3. If it is determined to be normal, analyze and determine again as follows:

[0034] S3.1. Determine whether the supercapacitor module needs compensation:

[0035] Then, the energy control management layer issues a compensation instruction 1 to the converter control management layer, and the compensation instruction 1 is executed by the DC-DC converter module 2 to adjust the duty cycle and frequency of the DC-DC converter module 2, and the DC-DC converter module 2 issues a current control instruction to compensate for the supercapacitor module to release or replenish energy;

[0036] S3.2. Determine the maintenance standby state:

[0037] Then, the energy control management layer issues a standby instruction to the converter control management layer, and the standby instruction is executed by the DC-DC converter module 2, and the super capacitor module is in standby mode;

[0038] S4. In the case of determining abnormality:

[0039] The arithmetic logic unit calculates the current value that the supercapacitor module needs to compensate based on the information obtained in S1; the transient response control strategy issues a compensation instruction 2 to the converter control management layer, and the compensation instruction 2 is executed by the DC-DC converter module 2 to adjust the duty cycle and frequency of the DC-DC converter module 2. The DC-DC converter module 2 issues a current control instruction, and the supercapacitor module compensates the current value of the DC bus;

[0040] S5. In the case of determining the second abnormality:

[0041] The arithmetic logic unit calculates the current value required for the battery module and the supercapacitor module to jointly compensate based on the information obtained in S1;

[0042] The virtual impedance control strategy issues compensation instruction three to the converter control management layer, and compensation instruction three is executed by DC-DC converter module one and DC-DC converter module two to adjust the duty cycle and frequency of DC-DC converter module one and DC-DC converter module two; DC-DC converter module one issues a current control instruction to control the battery module to compensate for the power value and current value of the DC bus; DC-DC converter module two issues a current control instruction to control the supercapacitor module to compensate for the current value of the DC bus.

[0043] Preferably, in the case of variant 1, the super capacitor module is fully powered;

[0044] The transfer function of the supercapacitor module current control is G i '=k' pi +k i ' i / s;

[0045] where k' pi , k i ' i It is the current control proportional coefficient of the supercapacitor module.

[0046] Preferably, in the case of the second variant, the battery module output current and the output current transfer function, as well as the supercapacitor module output current and the output current transfer function are given; the arithmetic logic unit of the energy control management layer calculates:

[0047] Virtual resistance of the battery module;

[0048] Virtual inductance of battery modules;

[0049] Virtual capacitance of supercapacitor module;

[0050] Add virtual resistance and virtual inductance to the DC-DC converter module 1;

[0051] Add virtual capacitors to DC-DC converter module 2;

[0052] The supercapacitor module and the battery module jointly provide current support;

[0053] The function under virtual impedance control is:

[0054]

[0055] H B (s) is the battery module output current transfer function;

[0056] H C (s) are the output current transfer functions of the supercapacitor modules;

[0057] where w n is the natural frequency, ξ is the damping ratio,

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The present invention provides a battery module, a supercapacitor module, an energy control management layer, a converter control management layer, a DC-DC converter module 1 and a DC-DC converter module 2. The cooperation of the battery module, the supercapacitor module, the energy control management layer, the converter control management layer, the DC-DC converter module 1 and the DC-DC converter module 2 improves the response speed of the system to the load voltage change and improves the reliability of the system. Through intelligent power distribution and virtual impedance control, the energy flow between the battery module and the supercapacitor module is optimized and the energy utilization efficiency is improved. The deep discharge and charging cycle of the battery module is effectively reduced, and its workload is reduced, thereby extending the overall life of the system. The problem that the power distribution strategy of the existing hybrid energy storage system cannot fully utilize the advantages of various energy storage units, resulting in the energy storage unit charge state exceeding the upper and lower limits, shortening the service life of the energy storage unit, and there is a safety hazard of breaking down the energy storage unit is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a flow chart of the present invention;

[0061] Figure 2 This is a closed-loop circuit control diagram of the supercapacitor module of the present invention;

[0062] Figure 3 It is the equivalent circuit diagram of the present invention. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] See also Figure 1 An embodiment of the present invention is: a battery energy storage system based on charging cycle monitoring, the battery energy storage system comprising: a battery module, a supercapacitor module, an energy control management layer, a converter control management layer, a DC-DC converter module one and a DC-DC converter module two.

[0065] The battery module includes a battery management system and a battery. The battery management system is used to monitor the voltage, temperature, and charge and discharge status of the battery to ensure safe operation of the battery and prevent overcharging, overdischarging, overheating, etc. At the same time, the battery management system can also ensure the balance of each single cell in the battery module through a balancing circuit, thereby extending the service life of the battery. The battery module is used for long-term energy storage and output. The battery module has a high energy density and a long cycle life, and is suitable for providing long-term continuous power output. The battery module can meet high power requirements and long-term discharge, and is suitable for application scenarios that require higher energy; the battery module is connected in series with the DC-DC converter module and connected to the DC bus.

[0066] The supercapacitor module includes a supercapacitor management system and a supercapacitor. The supercapacitor management system is used to monitor the voltage and temperature of the supercapacitor to ensure the safe and efficient operation of the supercapacitor, prevent overcharging and over-discharging, and ensure that the supercapacitor works in the best condition. The supercapacitor module is used for rapid charging and discharging and short-term high-power output; the supercapacitor module has an extremely high power density and can quickly store and release a large amount of electrical energy. It is suitable for occasions with large instantaneous energy demand, such as acceleration and braking energy recovery. The supercapacitor module has a fast charging and discharging speed and a large number of cycles, but its energy density is lower than that of the battery module; the supercapacitor module is connected in series with the DC-DC converter module 2 and connected to the DC bus.

[0067] The DC-DC converter module 1 and the DC-DC converter module 2 are both connected to the converter control management layer signal.

[0068] The converter control management layer is signal-connected to the energy control management layer.

[0069] The battery module and the supercapacitor module are both connected to the energy control management layer signal.

[0070] A power distribution control strategy is set inside the energy control management layer, and the power distribution control strategy includes a virtual impedance control strategy for adjusting the parameters of the DC-DC converter module one and the DC-DC converter module two, and a transient response control strategy for adjusting the parameters of the DC-DC converter module two. The power distribution control strategy controls the energy distribution between the battery module and the supercapacitor module through the converter control management layer, the DC-DC converter module one and the DC-DC converter module two.

[0071] The battery energy storage system also includes an interface and communication module, a user interface module and a protection and safety module.

[0072] The interface and communication module is responsible for realizing the communication and data transmission between the modules in the battery energy storage system; through communication protocols such as CAN and RS-485, it ensures data sharing and coordination between modules such as BMS, SCMS and HESS, so that the entire system can operate efficiently.

[0073] The user interface module is responsible for providing an interactive interface between the user and the system; the user interface module can display the system's operating status, energy flow, charging status and other information, and can set parameters or perform maintenance operations.

[0074] The protection and safety module is responsible for ensuring the safe operation of the system; the protection and safety module includes overcurrent, overvoltage, short circuit protection and other functions to ensure that the system can automatically cut off the circuit under abnormal circumstances to avoid damage to equipment and personal safety hazards.

[0075] The present invention provides a battery module, a supercapacitor module, an energy control management layer, a converter control management layer, a DC-DC converter module 1 and a DC-DC converter module 2. The cooperation of the battery module, the supercapacitor module, the energy control management layer, the converter control management layer, the DC-DC converter module 1 and the DC-DC converter module 2 improves the response speed of the system to the load voltage change and improves the reliability of the system. Through intelligent power distribution and virtual impedance control, the energy flow between the battery module and the supercapacitor module is optimized and the energy utilization efficiency is improved. The deep discharge and charging cycle of the battery module is effectively reduced, and its workload is reduced, thereby extending the overall life of the system. The problem that the power distribution strategy of the existing hybrid energy storage system cannot fully utilize the advantages of various energy storage units, resulting in the energy storage unit charge state exceeding the upper and lower limits, shortening the service life of the energy storage unit, and there is a safety hazard of breaking down the energy storage unit is solved.

[0076] See also Figure 1 , an embodiment provided by the present invention: the energy control management layer includes a data acquisition unit, and the data acquisition unit is used to collect the following information A:

[0077] Battery module state of charge, maximum available power, voltage and current;

[0078] The maximum available power, voltage and current of the supercapacitor module;

[0079] The filter inductance and voltage of the DC bus.

[0080] The power distribution control strategy sends a duty cycle control instruction and a frequency control instruction to the converter control management layer, and the converter control management layer adjusts the duty cycle and frequency of the pulses of the DC-DC converter module 1 and the DC-DC converter module 2 according to the above instructions, so as to adjust the power value and current value of the battery module through the DC-DC converter module 1, and adjust the current value of the supercapacitor module through the DC-DC converter module 2.

[0081] The energy control management layer includes an arithmetic logic unit, which is used to determine whether a sudden rise or drop occurs in the DC bus voltage, as follows:

[0082] When the DC bus voltage does not suddenly rise or fall, it is judged to be normal;

[0083] At this time, the power distribution control strategy sends a compensation instruction or a standby instruction acting on the supercapacitor module to the converter control management layer;

[0084] When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated does not exceed the power threshold of the supercapacitor module, it is determined to be abnormal state 1. In the case of abnormal state 1, the supercapacitor module provides full power supply.

[0085] At this time, the transient response control strategy sends a compensation instruction 2 acting on the DC-DC converter module 2 to the converter control management layer to adjust the duty cycle and frequency of the DC-DC converter module 2;

[0086] When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated exceeds the power threshold of the supercapacitor module, it is determined to be abnormal state 2;

[0087] At this time, the virtual impedance control strategy sends compensation instruction three to the converter control management layer, which acts on DC-DC converter module one and DC-DC converter module two at the same time to adjust the duty cycle and frequency of DC-DC converter module one and DC-DC converter module two.

[0088] In the case of variant 2, the output current and output current transfer function of the battery module, as well as the output current and output current transfer function of the supercapacitor module are given; the arithmetic logic unit of the energy control management layer calculates:

[0089] Virtual resistance of the battery module;

[0090] Virtual inductance of battery modules;

[0091] Virtual capacitance of supercapacitor module;

[0092] Add virtual resistance and virtual inductance to the DC-DC converter module 1;

[0093] Add virtual capacitors to DC-DC converter module 2;

[0094] The current support is provided by the supercapacitor module and the battery module.

[0095] The execution process of the power allocation control strategy includes the following steps:

[0096] S1, the data acquisition unit obtains information A;

[0097] S2, the arithmetic logic unit determines whether the DC bus voltage suddenly rises or drops:

[0098] When the DC bus voltage does not suddenly rise or fall, it is judged as normal and enters S3;

[0099] When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated does not exceed the power threshold of the supercapacitor module, it is determined to be abnormal state 1 and enters S4;

[0100] When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated exceeds the power threshold of the supercapacitor module, it is determined as abnormal state 2 and enters S5;

[0101] S3. If it is determined to be normal, analyze and determine again as follows:

[0102] S3.1. Determine whether the supercapacitor module needs compensation:

[0103] Then, the energy control management layer issues a compensation instruction 1 to the converter control management layer, and the compensation instruction 1 is executed by the DC-DC converter module 2 to adjust the duty cycle and frequency of the DC-DC converter module 2, and the DC-DC converter module 2 issues a current control instruction to compensate for the supercapacitor module to release or replenish energy;

[0104] S3.2. Determine the maintenance standby state:

[0105] Then, the energy control management layer issues a standby instruction to the converter control management layer, and the standby instruction is executed by the DC-DC converter module 2, and the super capacitor module is in standby mode;

[0106] S4. In the case of determining abnormality:

[0107] The arithmetic logic unit calculates the current value that the supercapacitor module needs to compensate based on the information obtained in S1; the transient response control strategy issues a compensation instruction 2 to the converter control management layer, and the compensation instruction 2 is executed by the DC-DC converter module 2 to adjust the duty cycle and frequency of the DC-DC converter module 2. The DC-DC converter module 2 issues a current control instruction, and the supercapacitor module compensates the current value of the DC bus;

[0108] S5. In the case of determining the second abnormality:

[0109] The arithmetic logic unit calculates the current value required for the battery module and the supercapacitor module to jointly compensate based on the information obtained in S1;

[0110] The virtual impedance control strategy issues compensation instruction three to the converter control management layer, and compensation instruction three is executed by DC-DC converter module one and DC-DC converter module two to adjust the duty cycle and frequency of DC-DC converter module one and DC-DC converter module two; DC-DC converter module one issues a current control instruction to control the battery module to compensate for the power value and current value of the DC bus; DC-DC converter module two issues a current control instruction to control the supercapacitor module to compensate for the current value of the DC bus.

[0111] See also Figures 1 to 3 , an embodiment provided by the present invention: a battery energy storage system based on charging cycle monitoring, the power distribution control strategy includes:

[0112] Transient response control: Utilizing the fast charging and discharging performance of the supercapacitor module, when a sudden change occurs in the high-frequency load, the supercapacitor module will be given priority to provide transient current to quickly respond to changes in the high-frequency load. If the high-frequency load demand exceeds the output capacity of the supercapacitor module, the battery module will gradually intervene to provide additional current support.

[0113] The specific process is as follows:

[0114] Load monitoring: Real-time monitoring of high-frequency load changes, and determination of transient power demand based on the rate of change of the high-frequency load.

[0115] Power allocation decision: In transient response, a power allocation threshold (50KW) is set. If the load demand is within the threshold, the supercapacitor module will provide full power. If it exceeds the threshold, the battery module and the supercapacitor module will jointly supply power, using dynamic proportional allocation.

[0116] First, the energy control management layer collects information such as SOC, maximum available power, voltage, current of battery module and super capacitor module, DC bus filter inductance, voltage, DC-DC converter module 1 current and DC-DC converter module 2 current. It determines whether the DC bus voltage suddenly increases or decreases. If so, it calculates the power compensation instruction; otherwise, it determines whether the power of the super capacitor module needs to be replenished or released to avoid the situation where the system cannot work when the super capacitor module needs to release or replenish energy.

[0117] The power compensation instruction of the supercapacitor module is:

[0118] P C =P Load -P B (1)

[0119] Where P C is the power that the supercapacitor module needs to provide, P Load is the power required by the high frequency load, P B is the power currently provided by the battery module. Load It cannot be measured, so the change in the current DC bus capacitor voltage is used instead:

[0120]

[0121] where i ref_C is the current regulation coefficient, C is the DC bus capacitance, Δu is the voltage change of the DC bus within a certain control cycle, Δt is the control period, and u dc is the current DC bus voltage, u C is the voltage of the supercapacitor module, is the given current of the previous control cycle.

[0122] Use DC-DC converter module 2 to build a small signal analysis model and obtain the linear model at the equilibrium point:

[0123]

[0124] Among them G vv , G vd , Z oo is the balance point, L is the filter inductor, s is the Laplace operator, D is the on-duty cycle of the second switch of the DC-DC converter module, i L is the current of the filter inductor, R is the load resistance, u 0 is the capacitor voltage of DC-DC converter module 2.

[0125] The closed-loop circuit control diagram of the supercapacitor module can be obtained from the small signal analysis model of the DC-DC converter module 2, as shown in Figure 2 .

[0126] The supercapacitor module is fully powered, and the transfer function of the supercapacitor module current control is as follows:

[0127] G i '=k' pi +k i ' i / s(4)

[0128] where k' pi , k i ' i It is the current control proportional coefficient of the supercapacitor module.

[0129] See also Figure 2 and Figure 3 , an embodiment provided by the present invention: a battery energy storage system based on charging cycle monitoring, the power distribution control strategy includes;

[0130] Virtual impedance control: By adding virtual segmented impedance to the voltage control of DC-DC converter module 1 and DC-DC converter module 2 of the battery module and supercapacitor module, the battery module is controlled to respond to low-frequency power components and the supercapacitor module to respond to high-frequency power components, so that the output voltage of the battery module and supercapacitor module presents a series impedance voltage regulation characteristic. A control strategy of adding virtual resistance and virtual inductance to the battery module voltage control unit and adding virtual capacitor to the supercapacitor module voltage control unit further optimizes power flow management.

[0131] Virtual impedance design: Configure virtual impedance for the battery module and supercapacitor module, and control the current distribution by adjusting the size of the virtual impedance.

[0132] Current regulation: Dynamically adjust the virtual impedance value according to actual needs, so that the supercapacitor module can play a greater role in high-frequency transient response, while the battery module maintains the best state in long-term stable output.

[0133] The virtual impedance is expressed as:

[0134]

[0135] Where Z VB , Z VC They are the virtual impedance and virtual capacitive reactance added by the voltage control unit of the battery module and supercapacitor module, respectively. V , L V are the virtual resistance and virtual inductance that constitute the virtual impedance of the battery module, C V is the virtual capacitor that constitutes the virtual capacitive reactance of the supercapacitor module, j is the imaginary unit, that is, the phase difference, and w is the angular frequency.

[0136] After the introduction of virtual impedance, the output voltage of the DC-DC converter module 1 of the battery module and the DC-DC converter module 2 of the supercapacitor module is:

[0137]

[0138] where u Bref 、u Cref is the output reference value of the battery module and supercapacitor module, s is the Laplace operator, i B 、i C It is the output current of the DC-DC converter module 1 of the battery module and the DC-DC converter module 2 of the supercapacitor module. Figure 3 An equivalent circuit diagram of adding virtual segmented impedance to the voltage control of the DC-DC converter module 1 of the battery module and the DC-DC converter module 2 of the supercapacitor module.

[0139] Because the sum of the DC bus voltages of the battery module and the supercapacitor module is equal to the total DC bus voltage, so:

[0140] i dc =i B +i C (7)

[0141] Solving equations (5), (6) and (7) together, we can obtain:

[0142]

[0143] Among them, H B (s), H C (s) are the output current transfer functions of the battery module and the supercapacitor module, which can be simplified to:

[0144]

[0145] where w n is the natural frequency, ξ is the damping ratio, H B (s) is a low-pass filter, H C (s) is a high-pass filter, so virtual segmented impedance is added in the voltage control of the DC-DC converter module 1 of the battery module and the DC-DC converter module 2 of the supercapacitor module to realize autonomous frequency division power distribution at the energy control management layer.

[0146] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A battery energy storage system based on charging cycle monitoring, characterized in that: The battery energy storage system comprises: a battery module, a supercapacitor module, an energy control management layer, a converter control management layer, a DC-DC converter module 1 and a DC-DC converter module 2; The battery module is connected in series with the DC-DC converter module 1 and connected to the DC bus; The super capacitor module is connected in series with the DC-DC converter module 2 and connected to the DC bus; The DC-DC converter module 1 and the DC-DC converter module 2 are both connected to the converter control management layer signal; The converter control management layer is signal-connected to the energy control management layer; The battery module and the supercapacitor module are both connected to the energy control management layer signal; A power distribution control strategy is set inside the energy control management layer, and the power distribution control strategy includes a virtual impedance control strategy for adjusting the parameters of the DC-DC converter module one and the DC-DC converter module two, and a transient response control strategy for adjusting the parameters of the DC-DC converter module two. The power distribution control strategy controls the energy distribution between the battery module and the supercapacitor module through the converter control management layer, the DC-DC converter module one and the DC-DC converter module two.

2. The battery energy storage system according to claim 1, characterized in that: The battery module includes a battery management system and a battery. The battery management system is used to monitor the voltage, temperature and charge and discharge status of the battery.

3. The battery energy storage system according to claim 2, characterized in that: The supercapacitor module includes a supercapacitor management system and a supercapacitor. The supercapacitor management system is used to monitor the voltage and temperature of the supercapacitor.

4. The battery energy storage system according to claim 3, characterized in that: The energy control management layer includes a data acquisition unit, which is used to collect the following information A: The state of charge, maximum available power, voltage and current of the battery module; The maximum available power, voltage and current of the supercapacitor module; The filter inductance and voltage of the DC bus.

5. The battery energy storage system according to claim 4, characterized in that: The power distribution control strategy sends a duty cycle control instruction and a frequency control instruction to the converter control management layer, and the converter control management layer adjusts the duty cycle and frequency of the pulses of the DC-DC converter module 1 and the DC-DC converter module 2 according to the above instructions, so as to adjust the power value and current value of the battery module through the DC-DC converter module 1, and adjust the current value of the supercapacitor module through the DC-DC converter module 2.

6. The battery energy storage system according to claim 5, characterized in that: The energy control management layer includes an arithmetic logic unit, which is used to determine whether a sudden rise or drop occurs in the DC bus voltage, as follows: When the DC bus voltage does not suddenly rise or fall, it is judged to be normal; At this time, the power distribution control strategy sends a compensation instruction or a standby instruction acting on the supercapacitor module to the converter control management layer; When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated does not exceed the power threshold of the supercapacitor module, it is determined to be abnormality 1; At this time, the transient response control strategy sends a compensation instruction 2 acting on the DC-DC converter module 2 to the converter control management layer to adjust the duty cycle and frequency of the DC-DC converter module 2; When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated exceeds the power threshold of the supercapacitor module, it is determined to be abnormal state 2; At this time, the virtual impedance control strategy sends compensation instruction three to the converter control management layer, which acts on DC-DC converter module one and DC-DC converter module two at the same time to adjust the duty cycle and frequency of DC-DC converter module one and DC-DC converter module two.

7. The battery energy storage system according to claim 6, characterized in that: The execution process of the power allocation control strategy includes the following steps: S1, the data acquisition unit obtains information A; S2, the arithmetic logic unit determines whether the DC bus voltage suddenly rises or drops: When the DC bus voltage does not suddenly rise or fall, it is judged as normal and enters S3; When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated does not exceed the power threshold of the supercapacitor module, it is determined to be abnormal state 1 and enters S4; When the DC bus voltage suddenly rises or drops, and the DC bus power to be compensated exceeds the power threshold of the supercapacitor module, it is determined as abnormal state 2 and enters S5; S3. If it is determined to be normal, analyze and determine again as follows: S3.

1. Determine whether the supercapacitor module needs compensation: Then, the energy control management layer issues a compensation instruction 1 to the converter control management layer, and the compensation instruction 1 is executed by the DC-DC converter module 2 to adjust the duty cycle and frequency of the DC-DC converter module 2, and the DC-DC converter module 2 issues a current control instruction to compensate for the supercapacitor module to release or replenish energy; S3.

2. Determine the maintenance standby state: Then, the energy control management layer issues a standby instruction to the converter control management layer, and the standby instruction is executed by the DC-DC converter module 2, and the super capacitor module is in standby mode; S4. In the case of determining abnormality: The arithmetic logic unit calculates the current value that the supercapacitor module needs to compensate based on the information obtained in S1; the transient response control strategy issues a compensation instruction 2 to the converter control management layer, and the compensation instruction 2 is executed by the DC-DC converter module 2 to adjust the duty cycle and frequency of the DC-DC converter module 2. The DC-DC converter module 2 issues a current control instruction, and the supercapacitor module compensates the current value of the DC bus; S5. In the case of determining the second abnormality: The arithmetic logic unit calculates the current value required for the battery module and the supercapacitor module to jointly compensate based on the information obtained in S1; The virtual impedance control strategy issues compensation instruction three to the converter control management layer, and compensation instruction three is executed by DC-DC converter module one and DC-DC converter module two to adjust the duty cycle and frequency of DC-DC converter module one and DC-DC converter module two; DC-DC converter module one issues a current control instruction to control the battery module to compensate for the power value and current value of the DC bus; DC-DC converter module two issues a current control instruction to control the supercapacitor module to compensate for the current value of the DC bus.

8. The battery energy storage system according to claim 7, characterized in that: In the case of abnormality 1, the super capacitor module is fully powered; The transfer function of the supercapacitor module current control is G i '=k' pi +k i ' i / s; where k' pi , k i ' i It is the current control proportional coefficient of the supercapacitor module.

9. The battery energy storage system according to claim 7, characterized in that: In the case of variant 2, the output current and output current transfer function of the battery module, as well as the output current and output current transfer function of the supercapacitor module are given; the arithmetic logic unit of the energy control management layer calculates: Virtual resistance of the battery module; Virtual inductance of battery modules; Virtual capacitance of supercapacitor module; Add virtual resistance and virtual inductance to the DC-DC converter module 1; Add virtual capacitors to DC-DC converter module 2; The supercapacitor module and the battery module jointly provide current support; The function under virtual impedance control is: H B (s) is the battery module output current transfer function; H C (s) are the output current transfer functions of the supercapacitor modules; where w n is the natural frequency, ξ is the damping ratio,

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