Energy management control method and battery energy storage architecture system thereof
By combining a pyramid-style hierarchical control architecture with a PID controller, the problems of uneven power distribution and poor compatibility in lithium battery energy storage systems are solved, achieving efficient, safe, and flexible power management of heterogeneous batteries and improving system stability and efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2021-03-11
- Publication Date
- 2026-04-14
AI Technical Summary
Existing lithium battery energy storage systems suffer from problems such as uneven power distribution, inflexible system expansion, and poor compatibility when using a mix of new and old batteries in large-scale applications. In particular, it is difficult to achieve efficient and safe power control when connecting retired batteries.
A pyramid-shaped hierarchical control architecture is adopted, which combines local controllers and central controllers to allocate power to the battery pack and energy storage cabinet respectively, and makes real-time adjustments with PID controllers to achieve compatibility and dynamic management of heterogeneous batteries.
It enables simultaneous networking of batteries of different brands and models, improves system stability and flexibility, ensures accurate power distribution and system robustness, avoids battery overcharging or over-discharging issues, and improves overall efficiency.
Smart Images
Figure CN121863480A_ABST
Abstract
Description
[0001] Divisional application
[0002] This application is a divisional application of application number 202110264640.3, filed on March 11, 2021, entitled "Pyramid-type large-scale battery energy storage architecture system and its energy management and control method". Technical Field
[0003] This invention belongs to the technical field of power energy storage systems, and generally relates to energy storage architecture systems with multiple battery packs and their energy management and control methods, specifically to an energy management and control method and its battery energy storage architecture system. Background Technology
[0004] With the increasing integration of new energy systems, especially distributed generation systems, the stability of the existing power grid has faced severe challenges. Energy storage systems can mitigate and stabilize the output power of intermittent renewable energy sources such as wind and solar power, thus improving the grid's ability to accommodate renewable energy and ensuring stable grid operation. For this reason, large-scale energy storage systems with long development histories and high power output are considered an inevitable choice for developing smart grids and achieving energy transition goals. Energy storage systems come in various forms, among which chemical energy storage, especially lithium-ion battery energy storage systems, has been widely used in the energy storage market in recent years due to its advantages such as high energy density, short construction period, high conversion efficiency, long lifespan, and convenient deployment. In particular, the huge demand for power batteries from new energy vehicles has reduced the cost of lithium-ion batteries by nearly 90% in the past decade, further promoting the development of lithium-ion battery energy storage technology.
[0005] With the large-scale installation and operation of lithium battery energy storage systems, the operating efficiency, lifespan, and safety and reliability of these systems are receiving increasing attention. Industry research on these issues ultimately focuses on energy management and power allocation strategies for energy storage systems. Currently, most power allocation methods for energy storage systems are based on the battery's state of charge (SOC). However, when batteries connected to a large-scale system differ in brand, capacity, and degradation rate, SOC-based allocation methods can exhibit significant deviations. Even with the addition of adaptive algorithms, fuzzy logic, neural network calculations, and other techniques, problems such as difficulty in real-time control and inflexible system expansion remain unresolved.
[0006] Furthermore, with the arrival of the power battery retirement wave, more and more retired power batteries will be connected to the cascade utilization energy storage system. At that time, there will also be energy storage scenarios where new and old batteries are used together. However, the manufacturers and remaining capacities of each retired battery may be different. Therefore, it is particularly important to know how to accept these retired batteries and carry out efficient and safe power control. Summary of the Invention
[0007] This invention provides an energy management and control method and its battery energy storage architecture system, aiming to solve at least one of the technical problems existing in the prior art.
[0008] The technical solution of this invention relates to an energy management and control method applied to a battery energy storage architecture system. The battery energy storage architecture system includes a battery energy storage system and a control system. The battery energy storage system includes multiple energy storage cabinets, each including an energy storage converter. The energy storage converters of the multiple energy storage cabinets are connected in parallel to an AC bus, which is connected to an external AC power grid via a transformer. Each energy storage cabinet contains multiple battery packs and multiple bidirectional DC choppers. Each battery pack has a battery management system, and each battery pack is connected in series with each bidirectional DC chopper. The bidirectional DC choppers are also connected to a DC bus, and the DC bus is connected to the DC terminal of the energy storage converter via a DC switch. The control system includes a central controller, cabinet controllers located within the energy storage cabinets, and local controllers. Each energy storage converter is connected to each cabinet controller, and multiple local controllers within each energy storage cabinet are connected to the cabinet controller within that energy storage cabinet. The multiple cabinet controllers of the multiple energy storage cabinets are connected to the central controller.
[0009] The energy management and control method is characterized by comprising the following steps:
[0010] S1. Collect information from the battery management system via the local controller, including rechargeable and dischargeable energy and power, and maximum and minimum allowable rechargeable and dischargeable power. S2. Based on the information from the battery management system and the bidirectional DC chopper, calculate the minimum acceptable rechargeable and dischargeable power, rechargeable and dischargeable energy surplus, and battery pack health status of the energy storage units in the battery pack, and send this information to the cabinet controller. S3. Based on the information from all subordinate local controllers and the maximum and minimum allowable rechargeable and dischargeable power from the energy storage converter, the cabinet controller determines the priority order and power allocation method for each local controller under different power allocation modes. It also calculates the minimum acceptable rechargeable and dischargeable power and the rechargeable and dischargeable energy surplus at the cabinet level, and sends this information to the central controller. S4. Based on the information from all subordinate cabinet controllers, the central controller determines the priority order and power allocation method for each... S5. Based on the central controller, select different power allocation modes and methods according to the magnitude and direction of the power demand and the minimum chargeable / dischargeable power of each, and send the calculated power allocation command to the relevant power cabinet controller; S6. Based on the power cabinet controller, select different power allocation modes and methods according to the magnitude and direction of the power demand sent by the central controller and the minimum chargeable / dischargeable power of each, and send the calculated power allocation command to the relevant local controller; S7. Based on the central controller, compare the real-time power status fed back by the grid-connected point's energy meter with the power demand, and input the comparison result into the PID controller to readjust the power demand so that the system output after deducting losses equals the power demand.
[0011] Another aspect of the technical solution of the present invention relates to a battery energy storage architecture system. The battery energy storage system includes multiple energy storage cabinets, each energy storage cabinet including an energy storage converter. The energy storage converters of the multiple energy storage cabinets are connected in parallel to an AC bus, which is connected to an external AC power grid via a transformer. Each energy storage cabinet includes multiple battery packs and multiple bidirectional DC choppers. Each battery pack has a battery management system, and each battery pack is connected in series with each bidirectional DC chopper. The bidirectional DC choppers are also connected to a DC bus, and the DC bus is connected to the DC terminal of the energy storage converter via a DC switch. The control system includes a central controller, cabinet controllers located in the energy storage cabinets, and local controllers. Each energy storage converter is connected to each cabinet controller, and multiple local controllers in each energy storage cabinet are connected to the cabinet controller in that energy storage cabinet. The multiple cabinet controllers of the multiple energy storage cabinets are connected to the central controller. The power distribution method is set through the cabinet controllers, wherein:
[0012] For special charging modes, the allocation method used is as follows:
[0013]
[0014] Among them, P alloc_LCU_i To determine the amount of power allocated to energy storage unit i, p Min_LCU_i ΔECHG_LCU represents the minimum acceptable charging power for energy storage unit i. i This represents the additional energy space that can be added to energy storage unit i. The sum of the additional energy space that can be added by all energy storage units. This is the sum of the minimum acceptable charging power of all energy storage units;
[0015] For special discharge modes, the allocation method used is as follows:
[0016]
[0017] Among them, ΔEDCHG_LCU i The energy space that can be released by energy storage unit i This is the sum of the energy space that can be released from all energy storage units;
[0018] For normal charging mode, the allocation method used is as follows:
[0019]
[0020] For normal discharge mode, the allocation method used is as follows:
[0021]
[0022] The central controller sets the power allocation method according to different charging and discharging modes. Specifically, for super special charging and discharging modes, all power demands are allocated to the device with the minimum chargeable and dischargeable power P. Min_LCU The electrical cabinet in question;
[0023] For special charging modes, the power allocation method used is as follows:
[0024]
[0025] Among them, P alloc_CCU_j To determine the amount of power allocated to the electrical control cabinet j, P Min_CCU_i ΔECHG_CCU represents the minimum acceptable charging power for the electrical control unit j. j This provides additional energy storage for the electrical control cabinet. The sum of the additional energy capacity available for all electrical control cabinets. This is the sum of the minimum acceptable charging power of all electrical cabinet controllers;
[0026] For special discharge modes, the power allocation method used is as follows:
[0027]
[0028] Among them, ΔEDCHG_CCU j The energy space that can be released by the electrical control unit j.
[0029] This is the sum of the energy release space available from all electrical control cabinets. This is the sum of the minimum acceptable discharge power of all electrical cabinet controllers;
[0030] For normal charging mode, the power allocation method used is as follows:
[0031]
[0032] For normal discharge mode, the power allocation method used is as follows:
[0033]
[0034] The beneficial effects of this invention are as follows.
[0035] First, by equipping each battery pack with an individual DC / DC converter for control, it is possible to simultaneously network new batteries, retired batteries, and batteries of different brands and models, thus achieving heterogeneous compatibility and providing a new approach for the upcoming large-scale battery retirement wave. Second, by setting up a local controller for each battery pack and DC / DC converter, the amount of data transmitted to the central controller can be reduced, bus congestion can be avoided, and the accuracy and speed of data transmission can be improved. Furthermore, in the event of a fault, the local controller can immediately disconnect the relevant DC switches, thereby ensuring the stable and safe operation of the large-scale system. Third, the pyramid-style hierarchical control mode allows for flexible networking of system capacities from kW to MW levels. The withdrawal and activation of individual energy storage units have no impact on the overall system, ensuring system robustness. Fourth, power allocation is dynamically managed, prioritizing and determining the power allocation based on the energy status of each energy storage unit, thereby ensuring that the system's available power is always at the maximum level, preventing any battery pack from prematurely charging or depleting its power and thus withdrawing from power allocation. Fifth, taking into full account the irreversible damage to lithium batteries caused by deep charging and deep discharging, as well as the capacity degradation of retired power batteries, the system mobilizes as many battery packs as possible to participate in power allocation during energy management. Simultaneously, when power demand is low and does not reach relevant thresholds, the system prioritizes allocating all power to a centralized power cabinet, avoiding excessive activation of DC / DC converters and PCS under light load, which would lead to low overall system efficiency. Sixth, the system incorporates a PID control loop, ensuring that the power output of the energy storage system, after deducting various internal losses, remains equal to or nearly equal to the power demand, thus achieving precise power response control. Attached Figure Description
[0036] Figure 1 This is a schematic diagram of the system topology of the present invention.
[0037] Figure 2 This is the energy management control flowchart of the present invention.
[0038] Figure 3 This is a general diagram of the power distribution flowchart from the central controller to the electrical cabinet controller of the present invention.
[0039] Figures 3a to 3g yes Figure 3 The segmentation diagram.
[0040] Figure 4 This is a flowchart of the power distribution process from the electrical cabinet controller to the local controller according to the present invention.
[0041] Figures 4a to 4g yes Figure 4 The segmentation diagram. Detailed Implementation
[0042] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.
[0043] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are used only to distinguish elements of the same type from one another. For example, a first element may also be referred to as a second element without departing from the scope of this disclosure, and similarly, a second element may also be referred to as a first element. The term "and / or" as used herein means any combination including one or more of the related listed items.
[0044] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. To explain the technical solutions and readability of the invention, specific terms are also used in this specification; these terms are only for describing particular embodiments and not for limiting the invention.
[0045] The specific abbreviations used in this article are explained as follows: BMS: Battery Management System; CCU (Coordinated Control Unit): Coordinated Control Unit; DC BUS: DC Transmission Bus; LCU (Local Control Unit): Local Control Unit; MCU (Master Control Unit): Central Control Unit; PCS: Energy Storage Converter; SOC: State of Charge.
[0046] like Figure 1 As shown, the architecture system provided by the present invention includes a battery energy storage system and a control system.
[0047] The battery energy storage system includes M energy storage cabinets 1 (M is an integer ≥ 1), each connected to an AC bus via its own energy storage converter PCS2, and then connected to the AC external power grid (not shown in the figure) via a transformer. Each energy storage cabinet contains N battery packs 3 (N is an integer ≥ 1) and a bidirectional DC / DC chopper 4 connected in series with them. One end of the chopper is connected to the DC terminal of the battery pack, and the other end is connected to the DC bus (not shown in the figure). The DC bus is connected to the DC terminal of the PCS2 via a DC switch. In a preferred embodiment, the battery packs may be retired power battery packs.
[0048] The control system includes a local controller (LCU) 5, an electrical cabinet controller (CCU) 6, and a central controller (MCU) 7.
[0049] In one embodiment, LCU 5 primarily manages the battery pack 3 and the bidirectional DC chopper 4. Specifically, it collects information from the battery management system (BMS) via the CAN bus, including voltage, current, charge / discharge energy and power, state of health (SOH), state of charge (SOC), etc., as well as information from the bidirectional DC chopper (DC / DC converter) such as voltage and maximum / minimum allowable charge / discharge power. This information is then used to calculate the minimum acceptable charge / discharge power and remaining charge / discharge energy of the energy storage unit. The necessary information is then transmitted to CCU 6 via the CAN bus, and LCU 5 receives power commands and start / stop commands from CCU 6, thus achieving local control of the energy storage unit. Simultaneously, in case of emergency faults, such as CAN communication interruption, DC / DC converter failure, or DC switch refusal to operate, LCU 5 can directly disconnect the switch, enabling rapid fault handling to protect system safety. Furthermore, users can use the LCU to set the usable capacity range and charge / discharge cut-off SOC range of the battery pack according to their needs and the age of the batteries, thereby extending battery life.
[0050] In one embodiment, the CCU primarily manages all subordinate LCUs and PCSs. Specifically, it receives information from all subordinate LCUs via CAN and the maximum / minimum allowable charge / discharge power from the PCS to determine the priority order and power allocation formula of LCUs under different power allocation modes. Simultaneously, it calculates the minimum acceptable charge / discharge power and the excess charge / discharge energy space at the cabinet level and sends this information to the MCU 7. It also receives power commands from the MCU 7. When the energy storage cabinet operates independently without connection to the MCU 7, the CCU 6 can directly accept external power dispatch, enabling autonomous operation of the small-scale energy storage system.
[0051] In one embodiment, the MCU 7 is mainly used in scenarios where it is necessary to control multiple energy storage cabinets simultaneously to achieve coordinated operation in different locations. Specifically, the MCU receives information sent by all subordinate CCUs to determine the priority order and power allocation formula of each CCU in different power allocation modes, and then sends power commands to each relevant CCU.
[0052] Figure 2 This is a flowchart of an energy management control method according to an embodiment of the present invention. The energy management control method shown may include the following steps S1 to S7.
[0053] In step S1, the LCU collects status information transmitted by the BMS and DC / DC of its respective battery pack via the CAN bus, including the battery pack's voltage, current, maximum / minimum charge / discharge power, absorbable and releaseable energy, state of health (SOH), state of charge (SOC), etc., as well as information such as the DC / DC's voltage and maximum / minimum charge / discharge power.
[0054] In step S2, based on the collected information, the LCU will perform the following operations:
[0055] First, calculate the minimum charge / discharge power of each energy storage unit: P Min_LCU .
[0056] Specifically, even when the DC switch is off, there is still some stray current inside the battery. Furthermore, due to sensor measurement errors, the current value measured by the system when the power is zero is not strictly zero. To distinguish the stray current inside the system and eliminate false power commands, a minimum starting current threshold I needs to be set based on the specific system conditions. Th If all battery packs in a system have similar or equal voltage levels, then I can be set directly. Th For a uniform constant value, such as 0.5A, in a hybrid network system, if the voltage levels differ significantly, it can be assumed that all battery packs have an equal P at the same SOC = A (e.g., SOC = 20%). Min_LCU (e.g., P) Min_LCU =300W), and then the current threshold can be calculated according to the following formula:
[0057]
[0058] U Bat This is the voltage value corresponding to the battery pack when SOC = A.
[0059] Because each battery pack has a different voltage, the calculated current threshold will also differ. Using the previous example, if the voltage U of battery pack i... Bat_i =300V, according to formula (1), the current threshold of the battery pack can be calculated as:
[0060]
[0061] According to formula (1), P Min_LCU It is a dynamic value that is directly proportional to the real-time voltage change.
[0062] Second, calculate the energy space that each energy storage unit can absorb (charge) and release (discharge):
[0063] ΔECHG_LCUi =E Max_i -E Now_i (2)
[0064] Where E Max_i E represents the energy that energy storage unit i can store when charging is cut off. Now_i ΔECHG_LCU represents the amount of electricity currently stored in energy storage unit i. i This refers to the additional energy space that can be added to energy storage unit i.
[0065]
[0066] Where E Min_i E represents the energy remaining in energy storage unit i when it is discharged. Now_i ΔEDCHG_LCU represents the amount of electricity currently stored in energy storage unit i. i The energy space that can be released by energy storage unit i.
[0067] Third, P Min_LCU ΔECHG_LCU, ΔEDCHG_LCU, SOH, and other voltage, current, and power values are sent to the CCU via the CAN bus.
[0068] In step S3, the CCU performs the following operations based on the information sent by all LCUs:
[0069] First, set different power distribution modes, including: special charging / discharging mode and normal charging / discharging mode.
[0070] Special charge / discharge modes refer to power demand P Request Greater than or equal to the minimum chargeable / dischargeable power P transmitted by all LCUs Min_LCU The minimum value, but less than the minimum charge / discharge power P transmitted by all LCUs. Min_LCU The sum is:
[0071] Min(P Min_LCU_i )≤P Request <∑(P Min_LCU_i (4)
[0072] Where i is an integer in the range [1, N]. This mode means that not all energy storage units will be activated to participate in power distribution; the CCU must determine which energy storage units to activate based on the overall energy state of each battery pack.
[0073] Additionally, if the power requirement P Request Less than the minimum charge / discharge power P transmitted by all LCUs Min_LCU The minimum value, that is:
[0074] P Request<Min(P Min_LCU_i (5)
[0075] Where i is an integer in [1, N].
[0076] Even if P Request If the value is not zero, the system will not start.
[0077] Furthermore, normal charge / discharge mode refers to the power demand P Request Greater than or equal to the minimum chargeable / dischargeable power P transmitted by all LCUs Min_LCU The sum of these values is less than or equal to the maximum charge / discharge power P transmitted by all LCUs. Max_LCU sum:
[0078] ∑(P Min_LCU_i )≤P Request ≤∑(P Max_LCU_i (6)
[0079] Where i is an integer in [1, N].
[0080] At this time, all energy storage units will start up, and when the power demand P Request Greater than the maximum charge / discharge power P transmitted by all LCUs Max_LCU When summing, the system will only satisfy the condition that the size equals ∑(P) Max_LCU_i The power requirements of this part.
[0081] Second, determine the priority order for power allocation for all LCUs.
[0082] In special charge / discharge modes, the CCU needs to prioritize all LCUs to select the energy storage units that require charging / discharging. The prioritization principle follows that when the system is charging, the energy storage unit with the smallest P value is prioritized. min_LCU The unit has higher priority because P Min_LCU A smaller value means the unit's energy state is relatively low and requires priority charging; if P Min_LCU If they are equal, the State of Health (SOH) of the two cells is further compared, with the cell having a higher SOH having higher priority; if the SOH is also equal, natural sorting is used; conversely, when the system discharges, the cell with a larger P... Min_LCU The unit has higher priority because P Min_LCU A larger value means that the energy state of the cell is relatively high, and it needs to be discharged preferentially; if P Min_LCUIf they are equal, the State of Health (SOH) of the two cells is further compared, and the cell with the higher SOH has higher priority. If the SOH is also equal, natural sorting is used. After several rounds of charging and discharging, all energy storage cells will have equal or similar energy states, thereby ensuring that the system can always be in the range of maximum available power and will not be removed from power distribution because a battery pack is prematurely charged / depleted.
[0083] Third, set the power distribution formula.
[0084] Different allocation formulas are used depending on the different charging / discharging modes.
[0085] The formula used in special charging modes is:
[0086]
[0087] Among them, P alloc_LCU_i P is the amount of power allocated to energy storage unit i. Min_LCU_i ΔECHG_LCU represents the minimum acceptable charging power for energy storage unit i. i This represents the additional energy space that can be added to energy storage unit i. The sum of the additional energy space that can be added by all energy storage units. This is the sum of the minimum acceptable charging power of all energy storage units.
[0088] The formula used for special discharge modes is:
[0089]
[0090] Among them, ΔEDCHG_LCU i The energy space that can be released by energy storage unit i It is the sum of the energy space that can be released by all energy storage units.
[0091] The formula used in normal charging mode is:
[0092]
[0093] The formula used in normal discharge mode is:
[0094]
[0095] Fourth, calculate the minimum acceptable charge / discharge power and energy space at the cabinet level.
[0096] The CCU is based on the minimum chargeable / dischargeable power P sent by all LCUs. Min_LCU Calculate the minimum charging / discharging power P of this cabinet level. Min_CCU and maximum charge / discharge power PMax_CCU :
[0097]
[0098]
[0099] Calculate the absorbable energy space ΔECHG_CCU and the releaseable energy space ΔEDCHG_CCU for this cabinet level:
[0100]
[0101]
[0102] Where i is an integer in [1, N].
[0103] Fifth, the CCU sends information such as the minimum / maximum charge / discharge power and energy space of the cabinet to the MCU.
[0104] In step S4, the MCU performs the following operations based on the information sent by the CCU:
[0105] First, set different power distribution modes, including: super special charge / discharge mode, special charge / discharge mode and normal charge / discharge mode.
[0106] Super special charge / discharge mode refers to power demand P Request Less than the minimum acceptable charge / discharge power P at the cabinet level sent by all CCUs Min_CCU The minimum value, but greater than the minimum charge / discharge power P transmitted by one of the LCUs. Min_LCU Minimum value, that is:
[0107] Min(P Min_LCU_i )≤P Request <Min(P Min_CCU_j (15)
[0108] Where i is an integer ∈ [1, N] and j is an integer ∈ [1, M].
[0109] This mode means that at least one energy storage unit can be started, but at most only one power cabinet can be started to meet the power demand.
[0110] Furthermore, special charge / discharge modes refer to P Request The minimum acceptable charge / discharge power P at the cabinet level transmitted by all CCUs is greater than or equal to this value. Min_CCU The minimum value, but less than the sum of these minimum powers, that is:
[0111] Min(P Min_CCU_j )≤P Request <Σ(PMin_CCU_j (16)
[0112] Where j is an integer ∈ [1, M].
[0113] This mode means that not all power cabinets will be activated; the MCU needs to determine which power cabinets will participate in power distribution.
[0114] Furthermore, normal charge / discharge mode refers to P Request Greater than or equal to the minimum chargeable / dischargeable power P transmitted by all CCUs Min_CCU The sum of these values is less than or equal to the maximum charge / discharge power P transmitted by all CCUs. Max_CCU sum:
[0115] Σ(P Min_CCU_j ) < P Request ≤∑(P Max_CCU_j (17)
[0116] Where j is an integer ∈ [1, M].
[0117] At this time, all energy storage units will start up, and when the power demand P Request Greater than the maximum charge / discharge power P transmitted by all CCUs Max_CCU When summing, the system will only satisfy the condition that the size equals ∑(P) Max_CCU_j The power requirements of this part.
[0118] Second, determine the priority order for power allocation for all CCUs.
[0119] The priority sorting method used by the MCU is consistent with the principle used by the CCU in step S3, that is, P is given priority during charging. Min_CCU Smaller electrical cabinets discharge in the opposite manner. If P is encountered... Min_CCU If they are equal, the natural ordering method is used directly.
[0120] Third, set the power distribution formula.
[0121] Different allocation formulas are used depending on the different charging / discharging modes.
[0122] The formula used in the super special charge / discharge mode is: allocate all power demand to the minimum charge / discharge power P. Min_LCU The control strategy avoids activating multiple PCS to participate in low-power distribution, which would reduce overall system efficiency and lead to frequent switching and activation of different battery packs to participate in power distribution.
[0123] The formula used in special charging modes is:
[0124]
[0125] Among them, P alloc_CCU_j To determine the amount of power allocated to the electrical control cabinet j, P Min_CCU_i ΔECHG_CCU represents the minimum acceptable charging power for the electrical control unit j. j This provides additional energy storage for the electrical control cabinet. The sum of the additional energy capacity available for all electrical control cabinets. This is the sum of the minimum acceptable charging power for all electrical cabinet controllers.
[0126] The formula used for special discharge modes is:
[0127]
[0128] Among them, ΔEDCHG_CCU j The energy space that can be released by the electrical control unit j. This is the sum of the energy release space available from all electrical control cabinets. This is the sum of the minimum acceptable discharge power of all electrical cabinet controllers.
[0129] The formula used in normal charging mode is:
[0130]
[0131] The formula used in normal discharge mode is:
[0132]
[0133] Step S5, the MCU schedules P according to the received external power. Request Based on the priority order and power allocation formula calculated in step S4, a list of CCUs participating in power allocation is obtained, and power commands are allocated to the corresponding CCUs.
[0134] In step S6, the CCU determines the list of LCUs participating in power allocation based on the power command issued by the MCU in step S3, and sends the power command and start / stop command to the corresponding LCUs.
[0135] Step S7, the central controller MCU will input the real-time power status and power demand P fed back by the electricity meter at the grid connection point. Request The comparison is performed, and the comparison result is input into the PID controller to readjust the power demand so that the system output after deducting various losses equals the power demand.
[0136] Specifically, lithium-ion batteries have an efficiency of only around 95%, and retired power batteries have an efficiency even lower than 95%. Furthermore, power electronics such as DC / DC converters and PCS incur energy losses during power conversion. Combined with the energy consumption of various auxiliary power supply systems, the overall efficiency of the energy storage system will be below 90%. For a large-scale energy storage system, a 10% difference between the actual output and power demand is a significant figure, greatly diminishing its effectiveness in responding to grid frequency regulation, voltage regulation, and peak shaving requirements. Therefore, to achieve precise control of output power, a PID controller is needed for rapid and effective power adjustment.
[0137] The process after priority sorting and power allocation in steps S1-S7 is as follows: Figure 3 and Figure 4 As shown. For clarity... Figure 3 The flowchart details will Figure 3 Details through segmentation Figures 3a to 3g To display, in which Figure 3 China has indicated Figures 3a to 3g The corresponding regional location. Similarly, for clarity... Figure 4 The flowchart details will Figure 4 Details through segmentation Figures 4a to 4g To display, in which Figure 4 China has indicated Figures 4a to 4g The corresponding regional location. Furthermore, to reduce the length of this document and in accordance with the principle of economy, all textual and logical flow descriptions in the accompanying figures are incorporated into this document without being repeated.
[0138] The pyramid-shaped control architecture of this invention is applicable not only to ordinary lithium batteries but also to energy storage systems using retired power batteries or a mix of new and old batteries. By configuring each battery with a separate DC / DC converter, the heterogeneous compatibility problem caused by simultaneously networking batteries of different brands and models can be solved. Furthermore, through a control strategy combining distributed and centralized control, the network power can be freely switched from kW to MW levels. This means that it can allow a single energy storage unit (cabinet level) to operate independently under external dispatch, or it can connect multiple distributed systems deployed in different locations through a central controller (MCU) to achieve large-scale energy storage collaboration. In addition, the system implements a dynamic power allocation method, so the activation and deactivation of each energy storage unit will not affect the overall system. Therefore, this control scheme can effectively solve the problems of difficult real-time control, inflexible system expansion, and poor compatibility in large-scale energy storage systems.
[0139] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention, as long as they achieve the technical effects of the present invention by the same means, should be included within the scope of protection of the present invention. Within the scope of protection of the present invention, the technical solutions and / or implementation methods can have various modifications and variations.
Claims
1. An energy management and control method applied to a battery energy storage architecture system, wherein the battery energy storage architecture system includes a battery energy storage system and a control system. The battery energy storage system includes multiple energy storage cabinets, each of which includes an energy storage converter. The energy storage converters of the multiple energy storage cabinets are connected to an AC bus, which is connected to the AC external power grid through a transformer. Each energy storage cabinet contains multiple battery packs and multiple bidirectional DC choppers, among which, Each battery pack has a battery management system, and each battery pack is connected in series with each bidirectional DC chopper. The bidirectional DC chopper is also connected to a DC bus, and the DC bus is connected to the DC terminal of the energy storage converter through a DC switch. The control system includes a central controller, cabinet controllers installed in the energy storage cabinets, and local controllers. Each energy storage converter is connected to each cabinet controller. Multiple local controllers in each energy storage cabinet are connected to the cabinet controllers in that energy storage cabinet. Multiple cabinet controllers in the multiple energy storage cabinets are connected to the central controller. The energy management and control method is characterized by comprising the following steps: S1. Collect information sent by the battery management system through the local controller, including rechargeable and dischargeable energy and power, and maximum and minimum allowable charge and discharge power; S2. Based on the information sent by the battery management system and the bidirectional DC chopper, calculate the minimum acceptable charge and discharge power, the surplus charge and discharge energy space, and the battery pack health status of the energy storage units in the battery pack, and send them to the cabinet controller. S3. The cabinet controller determines the priority order and power allocation method of each local controller under different power allocation modes based on the information sent by all subordinate local controllers and the maximum and minimum allowable charging and discharging power sent by the energy storage converter. At the same time, it calculates the minimum acceptable charging and discharging power and the surplus charging and discharging energy of the cabinet level and sends them to the central controller. S4. Based on the central controller, the priority order and power allocation method of each electrical cabinet controller in different power allocation modes are determined according to the information sent by all subordinate electrical cabinet controllers. S5. Based on the central controller, according to the magnitude and direction of the power demand and the result of comparing it with the minimum chargeable and dischargeable power of each, select different power allocation modes and allocation methods, and send the calculated power allocation instructions to the relevant cabinet controllers. S6. Based on the power cabinet controller, according to the magnitude and direction of the power demand sent by the central controller and the result of comparing it with the minimum chargeable and dischargeable power of each, select different power allocation modes and allocation methods, and send the calculated power allocation instructions to the relevant local controllers. S7. Based on the central controller, the real-time power status fed back by the electricity meter at the grid connection point is compared with the power demand, and the comparison result is input into the PID controller to readjust the power demand so that the system output after deducting losses is equal to the power demand.
2. The method according to claim 1, characterized in that, Step S2 includes: The local controller is configured as follows: Information sent by the battery management system and bidirectional DC chopper is collected via the communication bus; Calculate the minimum acceptable charge / discharge power and / or charge / discharge energy surplus of the energy storage unit of the battery pack. The power information is transmitted to the cabinet controller of the local energy storage cabinet via the communication bus, and the power command and start / stop command issued by the cabinet controller are received at the same time to realize local control of the energy storage unit of the local battery pack. The minimum chargeable / dischargeable power of each energy storage unit is calculated by the local controller. P Min_LCU =U Bat *AND Th Among them, I Th U is the minimum start-up current threshold for the energy storage unit. Bat This is the real-time voltage value of the battery pack; Calculate the energy absorption capacity of each energy storage unit. ΔECHG_LCU i =E Max_i -E Now_i Where E Max_i E represents the energy that energy storage unit i can store when charging is cut off. Now_i ΔECHG_LCU represents the amount of electricity currently stored in energy storage unit i. i This refers to the additional energy space that can be added to energy storage unit i.
3. The method according to claim 2, characterized in that, Step S2 further includes: Calculate the energy release space of each energy storage unit ΔEDCHG_LCU i =E Now_i -E Min_i Where E Min_i E represents the energy remaining in energy storage unit i when it is discharged. Now_i ΔEDCHG_LCU represents the amount of electricity currently stored in energy storage unit i. i The energy space that can be released by energy storage unit i.
4. The method according to claim 1, characterized in that: Step S3 includes: The electrical cabinet controller is configured as follows: The system receives information from the subordinate local controller via the communication bus, as well as the maximum or minimum allowable charging and discharging power sent by the energy storage converter, in order to determine the priority order and power allocation method of the local controller under different power allocation modes. Calculate the minimum acceptable charging and discharging power of the energy storage cabinet level and the surplus chargeable and discharging energy of the energy storage cabinet level, and send this information to the central controller, while receiving the power command issued by the central controller. Special charging / discharging modes and normal charging / discharging modes are set through the electrical cabinet controller. In the special charging / discharging mode, the power demand is greater than or equal to the minimum minimum chargeable / dischargeable power sent by all local controllers, and the power demand is less than the sum of the minimum chargeable / dischargeable power sent by all local controllers. In the normal charging / discharging mode, the power demand is greater than or equal to the sum of the minimum chargeable / dischargeable power sent by all local controllers, and the power demand is less than or equal to the sum of the maximum chargeable / dischargeable power sent by all local controllers. The power allocation and priority order of all local controllers are determined by the power cabinet controller, where: when the system is charging, the energy storage unit with the smaller minimum chargeable / dischargeable power has higher priority; if the minimum chargeable / dischargeable power is equal, the health status of the two energy storage units is further compared, and the energy storage unit with the higher health status has higher priority; if the state of health (SOH) is also equal, natural ordering is used. Conversely, when the system is discharging, the energy storage unit with the larger minimum chargeable / dischargeable power has higher priority; if the minimum chargeable / dischargeable power is equal, the health status of the two energy storage units is further compared, and the energy storage unit with the higher health status has higher priority; if the health status is also equal, natural ordering is used.
5. The method according to claim 4, characterized in that: Step S3 further includes: The power distribution method is set through the electrical cabinet controller, where: For special charging modes, the allocation method used is as follows: Among them, P alloc_LCU_i P is the amount of power allocated to energy storage unit i. Min_LCU_i ΔECHG_LCU represents the minimum acceptable charging power for energy storage unit i. i This represents the additional energy space that can be added to energy storage unit i. The sum of the additional energy space that can be added by all energy storage units. This is the sum of the minimum acceptable charging power of all energy storage units; For special discharge modes, the allocation method used is as follows: Among them, ΔEDCHG_LCU i The energy space that can be released by energy storage unit i This is the sum of the energy space that can be released from all energy storage units; For normal charging mode, the allocation method used is as follows: For normal discharge mode, the allocation method used is as follows: The minimum acceptable charging and discharging power and energy space of the electrical cabinet level are calculated by the electrical cabinet controller, wherein: the electrical cabinet controller calculates the total of the minimum charging and discharging power and the maximum charging and discharging power of the electrical cabinet level based on the minimum acceptable charging and discharging power sent by all local controllers. Calculate the total amount of information on the absorbable energy space and the releaseable energy space at this cabinet level; The minimum and maximum chargeable / dischargeable power and energy space information of the electrical cabinet level are sent to the central controller through the electrical cabinet controller.
6. The method according to claim 1, characterized in that, Step S4 includes: The central controller sets up a super special charge / discharge mode, a special charge / discharge mode, and a normal charge / discharge mode. In the super special charge / discharge mode, the power requirement is less than the minimum acceptable charge / discharge power at the cabinet level sent by all cabinet controllers, and greater than the minimum acceptable charge / discharge power sent by one of the local controllers. In the special charge / discharge mode, the power requirement is greater than or equal to the minimum acceptable charge / discharge power at the cabinet level sent by all cabinet controllers, and less than the sum of the minimum acceptable charge / discharge powers at the cabinet level sent by all cabinet controllers. In the normal charge / discharge mode, the power requirement is greater than or equal to the sum of the minimum acceptable charge / discharge powers sent by all cabinet controllers, and less than or equal to the sum of the maximum acceptable charge / discharge powers sent by all cabinet controllers. The power allocation and priority order of all energy storage cabinet controllers are determined by the central controller. Specifically, when charging, the energy storage cabinet with the smaller minimum chargeable and dischargeable power is given priority for charging, and when discharging, the energy storage cabinet with the larger minimum chargeable and dischargeable power is given priority for discharging. If multiple energy storage cabinets have the same minimum chargeable and dischargeable power, the charging and discharging order is adopted according to the natural order.
7. The method according to claim 6, characterized in that, Step S4 further includes: The power distribution method is set by the central controller according to different charging and discharging modes, wherein: For super-special charge / discharge modes, all power requirements are allocated to the minimum chargeable / dischargeable power P. Min_LCU The electrical cabinet in question; For special charging modes, the power allocation method used is as follows: Among them, P alloc_CCU_j To determine the amount of power allocated to the electrical control cabinet j, P Min_CCU_i ΔECHG_CCU represents the minimum acceptable charging power for the electrical control unit j. j This provides additional energy storage for the electrical control cabinet. The sum of the additional energy capacity available for all electrical control cabinets. This is the sum of the minimum acceptable charging power for all electrical cabinet controllers.
8. The method according to claim 7, characterized in that, Step S4 further includes: For special discharge modes, the power allocation method used is as follows: Among them, ΔEDCHG_CCU j The energy space that can be released by the electrical control unit j. This is the sum of the energy release space available from all electrical control cabinets. This is the sum of the minimum acceptable discharge power of all electrical cabinet controllers; For normal charging mode, the power allocation method used is as follows: For normal discharge mode, the power allocation method used is as follows:
9. A battery energy storage architecture system, comprising a battery energy storage system and a control system, characterized in that: The battery energy storage system includes multiple energy storage cabinets, each of which includes an energy storage converter. The energy storage converters of the multiple energy storage cabinets are connected to an AC bus, which is connected to the AC external power grid through a transformer. Each energy storage cabinet contains multiple battery packs and multiple bidirectional DC choppers. Each battery pack has a battery management system. Each battery pack is connected in series with each bidirectional DC chopper. The bidirectional DC chopper is also connected to a DC bus, and the DC bus is connected to the DC terminal of the energy storage converter through a DC switch. The control system includes a central controller, cabinet controllers installed in the energy storage cabinets, and local controllers. Each energy storage converter is connected to each cabinet controller. Multiple local controllers in each energy storage cabinet are connected to the cabinet controllers in that energy storage cabinet. Multiple cabinet controllers in the multiple energy storage cabinets are connected to the central controller. The power distribution method is set through the electrical cabinet controller, where: For special charging modes, the allocation method used is as follows: Among them, P alloc_LCU_i P is the amount of power allocated to energy storage unit i. Min_LCU_i ΔECHG_LCU represents the minimum acceptable charging power for energy storage unit i. i This represents the additional energy space that can be added to energy storage unit i. The sum of the additional energy space that can be added by all energy storage units. This is the sum of the minimum acceptable charging power of all energy storage units; For special discharge modes, the allocation method used is as follows: Among them, ΔEDCHG_LCU i The energy space that can be released by energy storage unit i This is the sum of the energy space that can be released from all energy storage units; For normal charging mode, the allocation method used is as follows: For normal discharge mode, the allocation method used is as follows: The power distribution method is set by the central controller according to different charging and discharging modes, wherein: For super-special charge / discharge modes, all power requirements are allocated to the minimum chargeable / dischargeable power P. Min_LCU The electrical cabinet in question; For special charging modes, the power allocation method used is as follows: Among them, P alloc_CCU_j To determine the amount of power allocated to the electrical control cabinet j, P Min_CCU_i ΔECHG_CCU represents the minimum acceptable charging power for the electrical control unit j. j This provides additional energy storage for the electrical control cabinet. The sum of the additional energy capacity available for all electrical control cabinets. This is the sum of the minimum acceptable charging power of all electrical cabinet controllers; For special discharge modes, the power allocation method used is as follows: Among them, ΔEDCHG_CCU j The energy space that can be released by the electrical control unit j. This is the sum of the energy release space available from all electrical control cabinets. This is the sum of the minimum acceptable discharge power of all electrical cabinet controllers; For normal charging mode, the power allocation method used is as follows: For normal discharge mode, the power allocation method used is as follows:
10. The battery energy storage architecture system according to claim 9, characterized in that, The local controller is configured as follows: Information sent by the battery management system and bidirectional DC chopper is collected via the communication bus; Calculate the minimum acceptable charge / discharge power and / or charge / discharge energy surplus of the energy storage unit of the battery pack. The power information is transmitted to the cabinet controller of the local energy storage cabinet via the communication bus, and the power command and start / stop command issued by the cabinet controller are received at the same time to realize local control of the energy storage unit of the local battery pack. The electrical cabinet controller is configured as follows: The system receives information from the subordinate local controller via the communication bus, as well as the maximum or minimum allowable charging and discharging power sent by the energy storage converter, in order to determine the priority order and power allocation method of the local controller under different power allocation modes. Calculate the minimum acceptable charging and discharging power of the energy storage cabinet level and the surplus chargeable and discharging energy of the energy storage cabinet level, and send this information to the central controller, while receiving the power command issued by the central controller. Special charging / discharging modes and normal charging / discharging modes are set through the electrical cabinet controller. In the special charging / discharging mode, the power demand is greater than or equal to the minimum minimum chargeable / dischargeable power sent by all local controllers, and the power demand is less than the sum of the minimum chargeable / dischargeable power sent by all local controllers. In the normal charging / discharging mode, the power demand is greater than or equal to the sum of the minimum chargeable / dischargeable power sent by all local controllers, and the power demand is less than or equal to the sum of the maximum chargeable / dischargeable power sent by all local controllers. The power allocation and priority order of all local controllers are determined by the power cabinet controller, where: when the system is charging, the energy storage unit with the smaller minimum chargeable / dischargeable power has higher priority; if the minimum chargeable / dischargeable power is equal, the health status of the two energy storage units is further compared, and the energy storage unit with the higher health status has higher priority; if the state of health (SOH) is also equal, natural ordering is used. Conversely, when the system is discharging, the energy storage unit with the larger minimum chargeable / dischargeable power has higher priority; if the minimum chargeable / dischargeable power is equal, the health status of the two energy storage units is further compared, and the energy storage unit with the higher health status has higher priority; if the health status is also equal, natural ordering is used. The electrical cabinet controller is configured as follows: When the energy storage cabinet operates independently without being connected to the central controller, it can directly accept external power dispatch to enable the autonomous operation of the local-scale energy storage system. The central controller is configured as follows: Receive information from all subordinate electrical cabinet controllers to determine the priority and power allocation method of each electrical cabinet controller under different power allocation modes, and issue power commands to each relevant electrical cabinet controller; The minimum acceptable charging and discharging power and energy space of the electrical cabinet level are calculated by the electrical cabinet controller, wherein: the electrical cabinet controller calculates the total of the minimum charging and discharging power and the maximum charging and discharging power of the electrical cabinet level based on the minimum acceptable charging and discharging power sent by all local controllers. Calculate the total amount of information on the absorbable energy space and the releaseable energy space at this cabinet level; The minimum and maximum chargeable / dischargeable power and energy space information of the electrical cabinet level are sent to the central controller through the electrical cabinet controller. The central controller sets up a super special charge / discharge mode, a special charge / discharge mode, and a normal charge / discharge mode. In the super special charge / discharge mode, the power requirement is less than the minimum acceptable charge / discharge power at the cabinet level sent by all cabinet controllers, and greater than the minimum acceptable charge / discharge power sent by one of the local controllers. In the special charge / discharge mode, the power requirement is greater than or equal to the minimum acceptable charge / discharge power at the cabinet level sent by all cabinet controllers, and less than the sum of the minimum acceptable charge / discharge powers at the cabinet level sent by all cabinet controllers. In the normal charge / discharge mode, the power requirement is greater than or equal to the sum of the minimum acceptable charge / discharge powers sent by all cabinet controllers, and less than or equal to the sum of the maximum acceptable charge / discharge powers sent by all cabinet controllers. The power allocation and priority order of all energy storage cabinet controllers are determined by the central controller. Specifically, when charging, the energy storage cabinet with the smaller minimum chargeable and dischargeable power is given priority for charging, and when discharging, the energy storage cabinet with the larger minimum chargeable and dischargeable power is given priority for discharging. If multiple energy storage cabinets have the same minimum chargeable and dischargeable power, the charging and discharging order is adopted according to the natural order.