A multi-level network type energy storage control and protection system

Abstract

The application relates to the technical field of energy storage control protection, and discloses a multi-level network-structured energy storage control protection system, which comprises a battery management unit, an energy management unit, a main control protection unit, a valve-based control protection unit and a sub-module control unit. The multi-level network-structured energy storage control protection system relates to multiple key technologies, including control strategy generation of the energy management unit, modulation wave generation of the main control protection unit, SOC (state of charge) equalization control strategy of the valve-based control protection unit, maintenance instruction generation of the sub control protection unit, thermal management and safety strategy of the battery management unit. Through comprehensive application of the above technologies, the multi-level network-structured energy storage control protection system can realize efficient operation and value creation of the energy storage system in a new power system on the basis of guaranteeing safety and quality.

Description

Technical Field

[0001] This invention relates to the field of energy storage control and protection technology, and in particular to a multi-level grid-type energy storage control and protection system. Background Technology

[0002] Multi-level grid-type energy storage control and protection system is a control and protection technology for energy storage systems, designed to improve the safety, reliability and efficiency of energy storage systems.

[0003] In the current technological context, with the rapid development of new energy sources, the global power system has entered a stage of high renewable energy penetration, posing challenges to the stable operation of the power grid. Grid construction technology, as one of the key supporting technologies for new power systems, has become a technological high ground for power system innovation in various countries. With the high proportion of new energy development, the power system faces problems such as supply and demand imbalance, decreased stability, fault isolation risks, and broadband oscillations. Although grid construction technology can provide certain inertia support and frequency and voltage stability capabilities, ensuring the long-term stability of the system in complex power system environments remains a challenge. Summary of the Invention

[0004] This invention sends control mode information and control target values ​​to the main control unit through the energy management unit, and receives unit voltage and current sampling and various monitoring information sent by the main control unit. The main control unit is responsible for overall reactive / active power control, adopts a unit-level control algorithm, and outputs a three-phase modulated wave to the valve base control unit. The valve base control unit coordinates the work of each unit in the three-phase PCS converter chain, completes the judgment and relay of downlink control commands and uplink status signals, completes the additional control of battery SOC balancing between modules in each phase, and finally outputs the corresponding control signal for each PCS unit. The control circuit SMC of the PCS unit receives the control signal sent by the VBC, adopts a modulation algorithm, and finally generates the drive pulse signal for the power device.

[0005] To achieve the above objectives, the present invention provides a multi-level grid-type energy storage control and protection system, comprising:

[0006] Battery management unit, energy management unit, main control and protection unit, valve base control and protection unit, and sub-module control unit;

[0007] The battery management unit is used to acquire the current operating status data of the energy storage system.

[0008] The energy management unit is used to acquire the operating status data of the energy storage system and generate first-level control commands by combining the operating status data of the energy storage system with system requirements.

[0009] The main control and protection unit is used to convert the primary control commands generated in the energy management unit into modulated waves.

[0010] The valve-based control and protection unit is used to coordinate the operation of each unit in the three-phase PCS converter chain; it is also used to generate secondary control commands corresponding to each PCS unit.

[0011] The sub-control and protection unit is used to combine secondary control commands and generate drive pulse signals for power devices using modulation algorithms.

[0012] In some embodiments of the present invention, the energy management unit is further configured to:

[0013] Historical operating status evaluation values ​​are generated based on the acquired historical operating status data of each component of the energy storage system;

[0014] Multiple control strategies are set based on historical data and historical operating status evaluation values;

[0015] Get the operating status data of each component of the energy storage system at the current sampling time node and generate a set of evaluation values ​​P of the operating status of each component of the energy storage system at the current sampling time node, P = {P1, P2, ..., Pi, ..., Pn};

[0016] Where Pi represents the operating status evaluation value of the i-th component in the current energy storage system;

[0017] Pi = H*(f1*Ti+f2+Vi);

[0018] Where H is the environmental impact coefficient, obtained through historical environmental data, f1 is the weight of the temperature evaluation value of the i-th component, Ti represents the temperature evaluation value of the i-th component, f2 is the load evaluation value of the i-th component, and Vi represents the load evaluation value of the i-th component.

[0019] A control strategy is generated based on the set of evaluation values ​​P of the operating status of each component of the energy storage system at the current sampling time node.

[0020] The system generates first-level control commands based on the control strategy, including: the control parameters of the current energy storage system, the voltage control target of the downstream DC / DC converter, and start / stop commands.

[0021] In some embodiments of the present invention, the main control protection unit is further configured to:

[0022] Based on the first-level control command, the modulation waves used for the control of each front-stage H-bridge in the current energy storage system are calculated to generate the three-phase modulation wave dataset of the front-stage H-bridge.

[0023] The three-phase modulation waveform data of the front-end H-bridge, the voltage control target of the rear-end DC / DC, and the start / stop command are sent to the valve base control and protection unit, and the system active safety strategy is executed at the same time.

[0024] The system's proactive security strategy includes:

[0025] A multi-level fault isolation point is set based on battery module-battery column-battery cluster-battery stack-PCS;

[0026] The fault isolation point is a multi-stage DC fast fuse protection device.

[0027] In some embodiments of the present invention, the valve base control and protection unit is further used for:

[0028] It receives the three-phase modulation wave sent by the main control and protection unit, and generates the SOC equalization control strategy between the batteries connected to each power unit based on the three-phase modulation wave inside the valve base control and protection unit.

[0029] The secondary control commands generated based on the SOC equalization control strategy include: each H-bridge carrier, modulation wave, or switching command;

[0030] The secondary control command is then sent to the sub-control and protection unit.

[0031] In some embodiments of the present invention, the generation of the SOC equalization control strategy among the batteries connected to each power unit further includes:

[0032] Two-layer equalization control: the first layer is an inter-phase SOC equalization control strategy; the second layer is an intra-phase SOC equalization control strategy.

[0033] The first layer is a current control algorithm, which combines command current, decoupling feedforward and PI control to control the centralized VSG output current to track the current command.

[0034] By combining interphase SOC equalization control with zero-sequence voltage injection or negative-sequence current injection, the interphase SOC equalization of the ABC three-phase batteries is controlled.

[0035] The second layer generates the modulation waves of each of the three-phase modules through a single-stage frequency-doubling carrier phase-shifting SPWM modulation algorithm;

[0036] The intra-phase SOC balance of the A, B, and C phase batteries is controlled by combining intra-phase SOC balance control.

[0037] In some embodiments of the present invention, the sub-control protection unit is further configured to:

[0038] Each PCS unit is equipped with a corresponding sub-control and protection unit. Based on the secondary control command, a drive pulse signal for the power device is generated and sent to the corresponding drive circuit. At the same time, a maintenance command for the PCS unit is generated based on the sub-control and protection unit.

[0039] In some embodiments of the present invention, when generating maintenance instructions for the PCS unit based on the sub-control protection unit, the process includes:

[0040] Based on the sub-control protection unit, obtain the relevant status evaluation value dataset A of the devices on the current PCS unit, A={A1,A2…Ai…An};

[0041] Where Ai represents the relevant state evaluation value of the i-th device in the current PCS unit, and n represents the number of devices in the current PCS unit;

[0042] Based on historical data, a threshold for the status evaluation value of each device is set. The relevant status evaluation value of the device in the current PCS unit is compared with the corresponding threshold to generate a relevant status evaluation information table for the current PCS unit.

[0043] Maintenance instructions for the PCS unit are generated based on the relevant status evaluation information table of the current PCS unit.

[0044] In some embodiments of the present invention, the battery management unit is further configured to:

[0045] The system controls the opening and closing of internal circuit breakers and contactors based on drive pulse signals, and simultaneously acquires the status monitoring data of each battery in each battery cluster and the SOC / SOH information of the battery and uploads it to the energy management unit.

[0046] Implement air-cooled battery thermal management strategies and active battery safety strategies.

[0047] In some embodiments of the present invention, the execution of the air-cooled battery thermal management strategy and the battery active safety strategy includes:

[0048] The thermal management strategy for air-cooled batteries is as follows:

[0049] The temperature of each cell in the battery module is monitored in real time, and an air duct is set at each cell. The temperature of each cell in the currently monitored battery module is controlled within a preset range by controlling the opening and closing of the air duct.

[0050] The temperature of the battery compartment is monitored in real time and controlled by air conditioning for cooling.

[0051] The active battery safety strategy is as follows:

[0052] The current working status of the battery module is determined based on the real-time temperature data of the current battery module, and an early warning command is generated based on the current working status of the battery module.

[0053] In some embodiments of the present invention, uploading to the energy management unit includes:

[0054] The battery management unit acquires battery status monitoring data and battery SOC / SOH information and uploads it to the sub-control and protection unit.

[0055] The sub-control and protection unit acquires H-bridge monitoring information and receives battery status monitoring data and battery SOC / SOH information, which are then sent to the valve base control and protection unit.

[0056] The valve-based control and protection unit sends the monitoring information related to the H-bridge, the battery status monitoring data, and the battery's SOC / SOH information to the main control and protection unit.

[0057] The main control and protection unit sends the monitoring information related to the H-bridge, the battery status monitoring data, and the battery's SOC / SOH information to the energy management unit.

[0058] Compared with existing technologies, the multi-level grid-type energy storage control and protection system provided in this invention has the following advantages:

[0059] By improving the mechanism from control parameter correction to modulation wave generation, the adaptability of the energy storage system to different operating conditions is enhanced, the power conversion efficiency is optimized, and unnecessary energy loss is reduced.

[0060] By generating a set of evaluation values ​​based on the historical and current operating status data of each component in the energy storage system, and setting various control strategies accordingly, this dynamic control strategy adjustment based on component status can fully take into account the performance changes of different components under different environmental and load conditions.

[0061] The valve-based control and protection unit can ensure that the SOC of the batteries connected to each power unit is consistent through SOC equalization control, avoiding overcharging or over-discharging of the batteries; effective SOC equalization helps to improve the overall performance of the battery pack, extend the battery life, and increase the available capacity of the energy storage system.

[0062] A multi-level fault isolation mechanism can quickly isolate the faulty part when a fault occurs at any point in the battery pack, preventing the fault from spreading and protecting the safety of the entire energy storage system.

[0063] The sub-control and protection unit obtains the relevant status evaluation value dataset of the devices on the PCS unit, compares it with the historically set thresholds, and generates maintenance instructions, which can promptly detect potential problems of the devices in the PCS unit.

[0064] The air-cooled battery thermal management strategy monitors the temperature of the cells and battery compartment in real time and performs corresponding temperature control to ensure that the battery operates within a suitable temperature range.

[0065] The active battery safety strategy determines the operating status and generates early warning commands based on the real-time temperature data of the battery module. It can take measures before the battery experiences abnormal conditions (such as excessive temperature which may lead to thermal runaway), effectively protecting the battery and preventing safety accidents caused by battery failure. Attached Figure Description

[0066] Figure 1 This is a structural diagram of a multi-level grid-type energy storage control and protection system provided in an embodiment of the present invention;

[0067] Figure 2 This is a schematic diagram of PQ decoupling control;

[0068] Figure 3 Schematic diagram of the main control and protection unit device;

[0069] Figure 4 This is a diagram of the multi-layer protection structure of an energy storage system;

[0070] Figure 5 Diagram of a multi-stage DC fast-blow protection structure for a battery;

[0071] Figure 6 Diagram of valve base control and protection unit device;

[0072] Figure 7 This is a schematic diagram of interphase SOC equalization control;

[0073] Figure 8 This is a schematic diagram of intra-phase SOC equalization control;

[0074] Figure 9 A schematic diagram showing the air duct setup on the battery cell;

[0075] Figure 10 This is a schematic diagram of the thermal management of the battery compartment-level air-cooled battery. Detailed Implementation

[0076] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0077] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0078] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0079] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0080] Example 1:

[0081] This invention provides a multi-level grid-type energy storage control and protection system, such as... Figure 1 As shown, it includes:

[0082] Battery management unit, energy management unit, main control and protection unit, valve base control and protection unit, and sub-module control unit;

[0083] The battery management unit is used to acquire the current operating status data of the energy storage system.

[0084] The energy management unit is used to acquire the operating status data of the energy storage system and generate first-level control commands by combining the operating status data of the energy storage system with system requirements.

[0085] The main control and protection unit is used to convert the primary control commands generated in the energy management unit into modulated waves.

[0086] The valve-based control and protection unit is used to coordinate the operation of each unit in the three-phase PCS converter chain; it is also used to generate secondary control commands corresponding to each PCS unit.

[0087] The sub-control and protection unit is used to combine secondary control commands and generate drive pulse signals for power devices using modulation algorithms.

[0088] Example 2:

[0089] The energy management unit is also used for:

[0090] Historical operating status evaluation values ​​are generated based on the acquired historical operating status data of each component of the energy storage system;

[0091] Multiple control strategies are set based on historical data and historical operating status evaluation values;

[0092] Get the operating status data of each component of the energy storage system at the current sampling time node and generate a set of evaluation values ​​P of the operating status of each component of the energy storage system at the current sampling time node, P = {P1, P2, ..., Pi, ..., Pn};

[0093] Where Pi represents the operating status evaluation value of the i-th component in the current energy storage system;

[0094] Pi = H*(f1*Ti+f2+Vi);

[0095] Where H is the environmental impact coefficient, obtained through historical environmental data, f1 is the weight of the temperature evaluation value of the i-th component, Ti represents the temperature evaluation value of the i-th component, f2 is the load evaluation value of the i-th component, and Vi represents the load evaluation value of the i-th component.

[0096] A control strategy is generated based on the set of evaluation values ​​P of the operating status of each component of the energy storage system at the current sampling time node.

[0097] The system generates first-level control commands based on the control strategy, including: the control parameters of the current energy storage system, the voltage control target of the downstream DC / DC converter, and start / stop commands.

[0098] In this embodiment, the PCS monitoring system can be configured independently or integrated with the substation's integrated automation backend to monitor the operating status of each component of the energy storage system. Different control methods and control parameters can be configured according to the system conditions and requirements, enabling the energy storage system to operate in different modes, including constant active power, constant reactive power, frequency regulation, voltage regulation, VF, VSG, etc., to achieve the predetermined control objectives. Furthermore, it can maintain mutual information and operation command transmission with AGC / AVC and the upper-level control (or dispatch center) through the communication interface.

[0099] The energy management unit has the following characteristics and advantages:

[0100] The proprietary SOPHIC integrated software platform offers better compatibility.

[0101] Mature experience in large power grid dispatching and substation monitoring platforms;

[0102] A cloud-based integrated monitoring and intelligent operation and maintenance system for new energy;

[0103] The independently developed real-time database has a data processing capacity of 2 million points and 5 million events per second for energy storage system energy management (planning curves, AGC, AVC);

[0104] The energy management unit and main control and protection unit determine the operating mode based on the equipment's application function objectives, including various modes such as constant active power, constant reactive power, frequency regulation, voltage regulation, VF operation, and VSG operation. The energy storage system operates in four quadrants and can simultaneously regulate active and reactive power; therefore, PQ decoupling control is adopted to achieve independent exchange of active and reactive power with the grid, such as... Figure 2 As shown.

[0105] The functions of each control strategy are as follows:

[0106] PQ mode: Outputs power quickly and accurately according to active and reactive power commands (grid-connected operation).

[0107] Frequency and voltage regulation mode: Adjusts active and reactive power according to frequency and voltage commands (grid-connected operation).

[0108] VF mode: Operates according to VF open-loop or droop characteristics (off-grid operation).

[0109] VSG mode: PCS grid-connected energy storage characteristics operation (grid-connected / off-grid)

[0110] Example 3:

[0111] The main control protection unit, such as Figure 3 As shown, it is also used for:

[0112] Based on the first-level control command, the modulation waves used for the control of each front-stage H-bridge in the current energy storage system are calculated to generate the three-phase modulation wave dataset of the front-stage H-bridge.

[0113] The three-phase modulation waveform data of the front-end H-bridge, the voltage control target of the rear-end DC / DC, and the start / stop command are sent to the valve base control and protection unit, and the system active safety strategy is executed at the same time.

[0114] The system's proactive security strategy includes:

[0115] A multi-level fault isolation point is set based on battery module-battery column-battery cluster-battery stack-PCS;

[0116] The fault isolation point is a multi-stage DC fast fuse protection device.

[0117] In this embodiment, the main control and protection unit primarily samples the system voltage and current, and receives information such as the battery's state of charge (SOC) and state of health (SOH). Combined with the control system's objectives, such as AC-side active and reactive power control and SOC balancing, it calculates the modulation waves used for each upstream H-bridge control stage. It then sends the three-phase modulation waves of the upstream H-bridges, the voltage control objectives of the downstream DC / DC converter, and start / stop commands to the valve-based control and protection unit. The main control and protection system can implement system-level control and protection strategies, such as proactive safety measures.

[0118] The system's proactive security strategy is described below:

[0119] Multiple dead-zone-free protection designs comprehensively protect the energy storage system, ensuring that the battery can be safely isolated in the event of a short circuit fault at any point. Figure 4 As shown.

[0120] Multi-level DC fast-blow fuse protection across battery modules, battery banks, battery clusters, battery stacks, and PCS ensures effective isolation of faults at any point within the battery pack, guaranteeing safe and reliable equipment operation. Figure 5 As shown.

[0121] The millisecond-level communication latency between the PCS and the battery management unit enables rapid battery protection, prevents overcharging and over-discharging, and effectively extends battery life.

[0122] Example 4:

[0123] The valve base control and protection unit is also used for:

[0124] It receives the three-phase modulation wave sent by the main control and protection unit, and generates the SOC equalization control strategy between the batteries connected to each power unit based on the three-phase modulation wave inside the valve base control and protection unit.

[0125] The secondary control commands generated based on the SOC equalization control strategy include: each H-bridge carrier, modulation wave, or switching command;

[0126] The secondary control command is then sent to the sub-control and protection unit.

[0127] In this embodiment, the valve-based control and protection unit is the brain and control core of the entire converter valve. The direct-connected energy storage system adopts a flexible DC transmission control architecture, and has accumulated ample experience in controlling numerous sub-units to coordinate and ensure stable and reliable operation under long-term low-power, high-power, and fault conditions. The valve-based control and protection unit device is as follows: Figure 6 As shown.

[0128] Because the PCS converter cascades a large number of power units, the amount of trigger signals sent and monitoring data received is substantial, thus ensuring the integrity of all data is crucial. NARI Relay Protection's valve-based control and protection unit is based on phase-division and time-division multi-channel high-speed parallel bus technology, enabling high-precision, multi-channel, and real-time valve-based control and protection. The highly integrated valve control device's valve-based control and protection unit employs a high-performance general-purpose hardware platform with powerful real-time processing capabilities. The DSP board uses a high-performance 32-bit dual-core processor + DSP + dual FPGA hardware structure, with multiple processors and FPGAs working in parallel. The 32-bit dual-core processor handles human-machine interface, communication, and printing functions; the DSP handles protection strategy calculations and output logic; and the two large-capacity FPGAs handle high-speed processing of real-time information from sub-modules. This high-performance hardware ensures that the device processes all sub-modules in real-time at each sampling interval, achieving phase-division and time-division multi-channel high-speed parallel data processing. The optical interface board can interact with the DSP board via an internal high-speed bus to exchange commands and information from the sub-control and protection unit, allowing for flexible expansion and offering versatility, flexibility, and ease of maintenance. Meanwhile, the highly compact valve-based control and protection unit design allows the entire device to function within a 6U chassis, increasing system reliability and saving space.

[0129] The highly integrated valve-based control and protection device based on phase-division and time-division multi-channel high-speed parallel bus technology can realize the integrated control of each sub-module, support redundant hot-swappable maintenance, meet the control requirements of up to 224 sub-modules, and can be flexibly applied to direct-connected energy storage systems of different voltages and capacity levels.

[0130] The valve-based control and protection unit (VPC) receives the three-phase modulation wave from the main control and protection unit (BCU) and performs SOC equalization control among the batteries connected to each power unit within the VPC. This generates the H-bridge carrier waves and modulation waves or switching commands, which are then sent to the sub-control and protection units. Simultaneously, the VPC uploads H-bridge related monitoring information to the BCU. Furthermore, the VPC uploads battery SOC / SOH information monitored by the BCMU to the BCU, enabling complex control algorithms such as phase-to-phase and intra-phase active energy equalization.

[0131] Example 5:

[0132] The method for generating the SOC equalization control strategy among the batteries connected to each power unit also includes:

[0133] Two-layer equalization control: the first layer is an inter-phase SOC equalization control strategy; the second layer is an intra-phase SOC equalization control strategy.

[0134] The first layer is a current control algorithm, which combines command current, decoupling feedforward and PI control to control the centralized VSG output current to track the current command.

[0135] By combining interphase SOC equalization control with zero-sequence voltage injection or negative-sequence current injection, the interphase SOC equalization of the ABC three-phase batteries is controlled.

[0136] The second layer generates the modulation waves of each of the three-phase modules through a single-stage frequency-doubling carrier phase-shifting SPWM modulation algorithm;

[0137] In this embodiment, the intra-phase SOC balance of the ABC three-phase battery is controlled by combining intra-phase SOC equalization.

[0138] The block diagram of the phase-to-phase and intra-phase active equalization control strategy algorithm is shown in the figure below. It includes two layers of equalization control: the first layer is the phase-to-phase SOC equalization control, as shown below. Figure 7 The second layer is intra-phase SOC equalization control, such as... Figure 8 This ensures the consistency of the State of Charge (SOC) of the energy storage batteries connected to each module. The modulation algorithm adopts an SPWM algorithm based on single-stage frequency doubling carrier phase shifting to improve the equivalent switching frequency and reduce high-frequency harmonic components.

[0139] The algorithm consists of two layers:

[0140] The first layer uses a conventional current control algorithm. Based on the commanded current, it employs decoupling feedforward and PI control to control the centralized VSG output current to track the current command. The algorithm output is a three-phase modulated wave. It's important to note that inter-phase SOC equalization control is incorporated into this layer to achieve SOC equalization of the A, B, and C phases of the battery. Inter-phase SOC equalization control can employ either zero-sequence voltage injection or negative-sequence current injection; zero-sequence voltage injection is used here.

[0141] The second layer uses a conventional single-stage frequency-doubling carrier phase-shifting SPWM (CPS-SPWM) modulation algorithm to generate the modulation waves for each of the three phase modules. In-phase SOC equalization control is incorporated into this layer, with a control implementation approach similar to the SVG in-phase voltage equalization control algorithm.

[0142] Example 6:

[0143] The sub-control and protection unit is also used for:

[0144] Each PCS unit is equipped with a corresponding sub-control and protection unit. Based on the secondary control command, a drive pulse signal for the power device is generated and sent to the corresponding drive circuit. At the same time, a maintenance command for the PCS unit is generated based on the sub-control and protection unit.

[0145] Example 7:

[0146] When generating maintenance instructions for the PCS unit based on the sub-control protection unit, the following are included:

[0147] Based on the sub-control protection unit, obtain the relevant status evaluation value dataset A of the devices on the current PCS unit, A={A1,A2…Ai…An};

[0148] Where Ai represents the relevant state evaluation value of the i-th device in the current PCS unit, and n represents the number of devices in the current PCS unit;

[0149] Based on historical data, a threshold for the status evaluation value of each device is set. The relevant status evaluation value of the device in the current PCS unit is compared with the corresponding threshold to generate a relevant status evaluation information table for the current PCS unit.

[0150] Maintenance instructions for the PCS unit are generated based on the relevant status evaluation information table of the current PCS unit.

[0151] As the core of the unit's control, the sub-control and protection unit needs to receive control commands sent from the valve base control and protection unit via optical fiber. These commands mainly include the control of power devices and the control of bypass switches. The unit then decodes the received control commands and sends them to the corresponding drive circuits. The triggering structure is shown in the figure below.

[0152] A PCS unit consists of multiple fully controllable devices, drive protection modules, power supply modules, resistors, capacitors and other electronic equipment. In order to control and monitor the electronic equipment of the valve unit, a sub-control and protection unit needs to be installed locally on each unit.

[0153] The sub-control and protection unit simultaneously collects the relevant status of the devices in the previous operation of the unit, encodes it, and sends it to the valve-based control and protection unit to monitor whether the unit is operating normally. This includes: switch status (closed, closed, etc.), device status (overvoltage, overcurrent, excessive dI / dt, etc.), and capacitor voltage. In addition, the sub-control and protection unit is also responsible for receiving power-on and power-off commands from the valve-based control and protection unit and sending them to the battery management unit (BMU), as well as transmitting battery SOC / SOH and other relevant information collected by the BMU to the valve-based control and protection unit.

[0154] Example 8:

[0155] The battery management unit is also used for:

[0156] The system controls the opening and closing of internal circuit breakers and contactors based on drive pulse signals, and simultaneously acquires the status monitoring data of each battery in each battery cluster and the SOC / SOH information of the battery and uploads it to the energy management unit.

[0157] Implement air-cooled battery thermal management strategies and active battery safety strategies.

[0158] Example 9:

[0159] When implementing the air-cooled battery thermal management strategy and the battery active safety strategy, the following are included:

[0160] The thermal management strategy for air-cooled batteries is as follows:

[0161] Real-time monitoring of the temperature of each cell in the battery module, and installation of air ducts at each cell, such as... Figure 9 As shown, the temperature of each cell in the currently monitored battery module is controlled within a preset range by controlling the opening and closing of the air duct;

[0162] Real-time monitoring of the battery compartment temperature and control of the battery compartment temperature via air conditioning cooling, such as... Figure 10 ;

[0163] The active battery safety strategy is as follows:

[0164] The current working status of the battery module is determined based on the real-time temperature data of the current battery module, and an early warning command is generated based on the current working status of the battery module.

[0165] In this embodiment, the battery management unit communicates and receives start / stop commands forwarded by the sub-control and protection unit to complete the opening and closing of internal circuit breakers and contactors. Simultaneously, it monitors the status of each battery within each battery cluster, collects SOC / SOH information, and sends it to the sub-control and protection unit. The battery management unit communication management system includes air-cooled battery thermal management strategies and active battery safety strategies.

[0166] The thermal management strategy for air-cooled batteries is as follows:

[0167] Battery module level: Full temperature monitoring and patented air duct design control the temperature difference between different cells: 0.5C cells are controlled within 3℃; 1.0C cells are controlled within 5℃, ensuring cell consistency after long-term operation.

[0168] Battery compartment level: Forced air cooling by air conditioning, system temperature control at 23±5℃, ensuring that the battery cells are always within the long lifespan temperature range.

[0169] Battery management unit communication can also realize active battery safety strategies. It uses early warning, alarm and protection information as basic criteria, and combines the absolute value and sudden change of physical quantities such as temperature to form composite criteria. It can judge thermal runaway based on unexpected temperature rise, and can also realize some complex trend prediction through big data analysis of temperature and battery internal resistance.

[0170] The air-cooled battery thermal management strategy and active battery safety strategy implemented by the battery management unit are crucial to the safe operation of the battery. The air-cooled battery thermal management strategy ensures that the battery operates within a suitable temperature range by monitoring the temperature of the cells and battery compartment in real time and performing corresponding temperature control.

[0171] The active battery safety strategy determines the operating status and generates early warning commands based on the real-time temperature data of the battery module. It can take measures before the battery experiences abnormal conditions (such as excessive temperature which may lead to thermal runaway), effectively protecting the battery and preventing safety accidents caused by battery failure.

[0172] The PCS unit receives application layer control commands to charge and discharge the battery, and uploads various alarm information from the battery management unit to the monitoring backend to ensure the safe, stable and efficient operation of the battery.

[0173] The sub-control and protection unit communicates with the battery management unit and dynamically adjusts the charging and discharging parameters and executes corresponding actions based on the data provided by the battery management system, so as to realize closed-loop control of charging and discharging voltage and current to meet the various performance indicators of the battery in each charging and discharging stage.

[0174] The overall control architecture design ensures the rapid and effective flow of control information within the grid-connected energy storage system.

[0175] Example 10:

[0176] The process of uploading to the energy management unit includes:

[0177] The battery management unit acquires battery status monitoring data and battery SOC / SOH information and uploads it to the sub-control and protection unit.

[0178] The sub-control and protection unit acquires H-bridge monitoring information and receives battery status monitoring data and battery SOC / SOH information, which are then sent to the valve base control and protection unit.

[0179] The valve-based control and protection unit sends the monitoring information related to the H-bridge, the battery status monitoring data, and the battery's SOC / SOH information to the main control and protection unit.

[0180] The main control and protection unit sends the monitoring information related to the H-bridge, the battery status monitoring data, and the battery's SOC / SOH information to the energy management unit.

[0181] Finally, it should be noted that those skilled in the art can obviously make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations.

[0182] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A multi-level grid-type energy storage control and protection system, characterized in that, include: Battery management unit, energy management unit, main control and protection unit, valve base control and protection unit, and sub-module control unit; The battery management unit is used to acquire the current operating status data of the energy storage system. The energy management unit is used to acquire the operating status data of the energy storage system and generate first-level control commands by combining the operating status data of the energy storage system with system requirements. The main control and protection unit is used to convert the primary control commands generated in the energy management unit into modulated waves. The valve-based control and protection unit is used to coordinate the operation of each unit in the three-phase PCS converter chain; it is also used to generate secondary control commands corresponding to each PCS unit. The sub-control and protection unit is used to combine secondary control commands and generate drive pulse signals for power devices using modulation algorithms; The main control and protection unit is also used for: Based on the first-level control command, the modulation waves used for the control of each front-stage H-bridge in the current energy storage system are calculated to generate the three-phase modulation wave dataset of the front-stage H-bridge. The three-phase modulation waveform data of the front-end H-bridge, the voltage control target of the rear-end DC / DC, and the start / stop command are sent to the valve base control and protection unit, and the system active safety strategy is executed at the same time. The system's proactive security strategy includes: A multi-level fault isolation point is set based on battery module-battery column-battery cluster-battery stack-PCS; The fault isolation point is a multi-stage DC fast fuse protection device; The valve base control and protection unit is also used for: It receives the three-phase modulation wave sent by the main control and protection unit, and generates the SOC equalization control strategy between the batteries connected to each power unit based on the three-phase modulation wave inside the valve base control and protection unit. The secondary control commands generated based on the SOC equalization control strategy include: each H-bridge carrier, modulation wave, or switching command; And send the secondary control command to the sub-control protection unit; The method for generating the SOC equalization control strategy among the batteries connected to each power unit also includes: Two-layer equalization control: the first layer is an inter-phase SOC equalization control strategy; the second layer is an intra-phase SOC equalization control strategy. The first layer is a current control algorithm, which combines command current, decoupling feedforward and PI control to control the centralized VSG output current to track the current command. By combining interphase SOC equalization control with zero-sequence voltage injection or negative-sequence current injection, the interphase SOC equalization of the ABC three-phase batteries is controlled. The second layer generates the modulation waves of each of the three-phase modules through a single-stage frequency-doubling carrier phase-shifting SPWM modulation algorithm; The intra-phase SOC balance of the A, B, and C phase batteries is controlled by combining intra-phase SOC balance control.

2. The multi-level grid-type energy storage control and protection system as described in claim 1, characterized in that, The energy management unit is also used for: Historical operating status evaluation values ​​are generated based on the acquired historical operating status data of each component of the energy storage system; Multiple control strategies are set based on historical data and historical operating status evaluation values; Get the operating status data of each component of the energy storage system at the current sampling time node and generate a set of evaluation values ​​P of the operating status of each component of the energy storage system at the current sampling time node, P = {P1, P2, ..., Pi, ..., Pn}; Where Pi represents the operating status evaluation value of the i-th component in the current energy storage system; Pi = H*(f1*Ti+f2+Vi); Where H is the environmental impact coefficient, obtained through historical environmental data, f1 is the weight of the temperature evaluation value of the i-th component, Ti represents the temperature evaluation value of the i-th component, f2 is the load evaluation value of the i-th component, and Vi represents the load evaluation value of the i-th component. A control strategy is generated based on the set of evaluation values ​​P of the operating status of each component of the energy storage system at the current sampling time node. The system generates first-level control commands based on the control strategy, including: the control parameters of the current energy storage system, the voltage control target of the downstream DC / DC converter, and start / stop commands.

3. The multi-level grid-type energy storage control and protection system as described in claim 1, characterized in that, The sub-control and protection unit is also used for: Each PCS unit is equipped with a corresponding sub-control and protection unit. Based on the secondary control command, a drive pulse signal for the power device is generated and sent to the corresponding drive circuit. At the same time, a maintenance command for the PCS unit is generated based on the sub-control and protection unit.

4. The multi-level grid-type energy storage control and protection system as described in claim 3, characterized in that, When generating maintenance instructions for the PCS unit based on the sub-control protection unit, the following are included: Based on the sub-control protection unit, obtain the relevant status evaluation value dataset A of the devices on the current PCS unit, A={A1,A2…Ai…An}; Where Ai represents the relevant state evaluation value of the i-th device in the current PCS unit, and n represents the number of devices in the current PCS unit; Based on historical data, a state evaluation value threshold is set for each device. The relevant state evaluation value of the device in the current PCS unit is compared with the corresponding threshold to generate a relevant state evaluation information table for the current PCS unit. Maintenance instructions for the PCS unit are generated based on the relevant status evaluation information table of the current PCS unit.

5. The multi-level grid-type energy storage control and protection system as described in claim 4, characterized in that, The battery management unit is also used for: The system controls the opening and closing of internal circuit breakers and contactors based on drive pulse signals, and simultaneously acquires the status monitoring data of each battery in each battery cluster and the SOC / SOH information of the battery and uploads it to the energy management unit. Implement air-cooled battery thermal management strategies and active battery safety strategies.

6. The multi-level grid-type energy storage control and protection system as described in claim 5, characterized in that, When implementing the air-cooled battery thermal management strategy and the battery active safety strategy, the following are included: The thermal management strategy for air-cooled batteries is as follows: The temperature of each cell in the battery module is monitored in real time, and an air duct is set at each cell. The temperature of each cell in the currently monitored battery module is controlled within a preset range by controlling the opening and closing of the air duct. The temperature of the battery compartment is monitored in real time and controlled by air conditioning for cooling. The active battery safety strategy is as follows: The current working status of the battery module is determined based on the real-time temperature data of the current battery module, and an early warning command is generated based on the current working status of the battery module.

7. The multi-level grid-type energy storage control and protection system as described in claim 6, characterized in that, The process of uploading to the energy management unit includes: The battery management unit acquires battery status monitoring data and battery SOC / SOH information and uploads it to the sub-control and protection unit. The sub-control and protection unit acquires H-bridge monitoring information and receives battery status monitoring data and battery SOC / SOH information, which are then sent to the valve base control and protection unit. The valve-based control and protection unit sends the monitoring information related to the H-bridge, the battery status monitoring data, and the battery's SOC / SOH information to the main control and protection unit. The main control and protection unit sends the monitoring information related to the H-bridge, the battery status monitoring data, and the battery's SOC / SOH information to the energy management unit.

Images