Multi-source power flexible interconnection interface device and control method

Abstract

The present application relates to a kind of multi-source electric power flexible interconnection interface device and control method, by integrating DC / DC converter module, DC / AC bidirectional converter module, core controller and intelligent edge terminal, realize the new energy centralized grid connection of multi-energy, multi-electric system conversion, using core controller and the intelligent edge terminal that fused 5G communication module realizes the information acquisition, transmission and power coordination, energy management of multi-energy, finally realize the energy conversion efficiency of high-level multi-energy grid connection, reduce energy transmission loss, more flexibly satisfy power grid electricity demand and energy saving and carbon reduction environmental protection demand.Support CAN net, ethernet, RS485 and 5G and so on communication mode.

Description

Technical Field

[0001] The present invention relates to a control technology, and in particular to a multi-source power flexible interconnection interface device and a control method. Background Art

[0002] The proportion of distributed energy devices such as wind power, photovoltaics, and energy storage connected to the grid is increasing year by year. These distributed energy devices typically connect to the main grid or microgrid through multiple points of access, with a single type of decentralized grid connection. Centralized access for multiple energy types is not achieved, resulting in inefficient energy utilization. Research on the current status of multi-energy centralized access devices reveals that energy routers are a common device for multi-energy centralized grid connection. However, energy routers have limitations in multi-energy coordinated regulation and multi-timescale energy management. They also lack the corresponding functional modules or equipment to perform high-intensity data collection, computing, and communication applications, making it difficult to achieve regional energy autonomy and cloud-edge collaboration for multi-energy grid connection. Summary of the Invention

[0003] To address the above problems, a multi-source power flexible interconnection interface device and control method are proposed. By integrating DC / DC conversion modules, DC / AC bidirectional conversion modules, core controllers and intelligent edge terminals, centralized grid connection of new energy with multi-energy and multi-power conversion is realized. The core controller and the intelligent edge terminal integrated with 5G communication modules are used to realize multi-energy information collection, transmission, power coordination and energy management, and ultimately achieve high-level multi-energy grid connection with energy conversion efficiency, reduce energy transmission loss, and more flexibly meet the power demand of the power grid and the environmental protection needs of energy conservation and carbon reduction.

[0004] The technical solution of the present invention is: a multi-source power flexible interconnection interface device, including four DC / DC bidirectional conversion modules, one bidirectional DC / AC conversion module, an intelligent edge terminal and a core controller;

[0005] The diesel generator set is connected to a 700V DC bus through a bidirectional DC / AC converter module. The DC bus is then connected to energy storage batteries, supercapacitors, wind turbines, and photovoltaic panels through four DC / DC bidirectional converter modules.

[0006] The intelligent edge terminal collects and processes the current, voltage, and power information of the DC / AC bidirectional conversion module and the DC / DC bidirectional conversion module in the form of communication. It then transmits the processed information to the core controller via Ethernet and uploads it to the cloud-network collaborative management platform via the 5G module. The cloud-network collaborative management platform processes and predicts the data, and the predicted data is transmitted back to the intelligent edge terminal via the 5G network. The intelligent edge terminal then transmits the information to the core controller via Ethernet. After receiving all the information, the core controller outputs operation control instructions to the DC / AC bidirectional conversion module and the DC / DC bidirectional conversion module. At the same time, the core controller sends all the information to the intelligent edge terminal via Ethernet. The intelligent edge terminal then outputs logic control instructions. At the same time, the intelligent edge terminal uploads all instructions to the cloud-network collaborative management platform via the 5G module.

[0007] The intelligent edge terminal and core controller control four DC / DC bidirectional conversion modules and one bidirectional DC / AC conversion module to work together to achieve on-grid and off-grid operation of multiple new energy sources such as energy storage batteries, supercapacitors, wind power and photovoltaics.

[0008] Preferably, the intelligent edge terminal and the core controller communicate with each other through an Ethernet port in the external connector.

[0009] Preferably, the 5G gateway in the external connector of the intelligent edge terminal realizes long-distance transmission of information through the 5G power information network architecture.

[0010] Preferably, the 5G power information network architecture adopts a cloud-network collaborative management platform architecture, in which the cloud server is used to realize data storage and big data analysis and prediction; the edge side adopts intelligent edge terminals to coordinate with the cloud server for regulation, which is close to the data source, reduces the delay between data production and decision-making, filters useless data, and reduces transmission bandwidth.

[0011] A control method for a multi-source power flexible interconnection interface device actively switches the operating modes of a DC converter and a bidirectional converter by detecting the on-grid and off-grid status of the multi-source power flexible interconnection interface device. When a core controller reads a grid-connected instruction from an intelligent edge terminal, it sends a "constant current mode" instruction to the DC / AC bidirectional converter. After the DC / AC bidirectional converter receives the "constant current mode" instruction, the phase-locked loop within the DC / AC bidirectional converter constantly reads the phase angle of the output waveform of the grid-connected generator set. After waiting for 2 seconds, the DC / AC bidirectional converter automatically closes the grid-connected switch based on the phase angle information read by the phase-locked loop, completing the grid-connected action. In the grid-connected mode, if the core controller receives a mode switching instruction for the DC converter module, it outputs a mode switching instruction to the DC converter module, and the DC converter module immediately changes the conversion mode.

[0012] After receiving the instruction from the intelligent edge terminal, the core controller sends a "constant voltage mode" instruction to the DC / AC bidirectional converter. The DC / AC bidirectional converter operates in constant voltage mode to achieve independent load carrying.

[0013] Furthermore, by reading the prediction data and power constraint data from the cloud-network collaborative management platform, and taking the actual operating point of each device at the current moment t as the optimization starting point, the power baseline rolling optimization solution is performed for M consecutive time periods, so that the obtained operating baseline of each device is predictive and redundant, and the operating result of the first time period in the solution result is output as the reference operating point of each layer of the power conversion module; after entering the next moment, the optimization starting point of the power baseline rolling optimization will be updated to the moment t+1, and the starting point data will be updated to the actual operating point of each device at the moment t+1, and enter the next iteration.

[0014] Furthermore, the objective function of the power baseline rolling optimization includes two parts. The first part is the difference between the actual active power output of the diesel generator set and the target value, and the second part is a penalty term for the charging and discharging power of the energy storage battery to prevent simultaneous charging and discharging during the decision optimization process.

[0015] The beneficial effects of the present invention are: the multi-source power flexible interconnection interface device and control method of the present invention have a maximum power transmission power of 50kW; have a maximum number of 5 power equipment interfaces; and support communication modes such as CAN network, Ethernet, RS485 and 5G. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a layout diagram of the multi-source power flexible interconnection interface device of the present invention;

[0017] Figure 2 This is a hardware diagram of the edge terminal in the multi-source power flexible interconnection interface device of the present invention;

[0018] Figure 3 This is a schematic diagram of the 5G power information network architecture solution;

[0019] Figure 4 This is a software platform framework diagram of the multi-source power flexible interconnection interface device of the present invention;

[0020] Figure 5 This is a functional decomposition diagram of the multi-source power flexible interconnection interface device of the present invention. DETAILED DESCRIPTION

[0021] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0022] The multi-source power flexible interconnection interface device fuses 5G communication technology. Inside the device, four DC / DC bidirectional conversion modules and one bidirectional DC / AC conversion module are used to realize the parallel and off-grid operation of wind power, photovoltaic, energy storage battery and super capacitor. The device is arranged as shown in Figure 1 The diesel generator set (G1\G2) is connected to the 700V DC bus through the bidirectional DC / AC conversion module. The DC bus is connected to the energy storage battery, super capacitor, wind turbine and photovoltaic panel through four DC / DC bidirectional conversion modules.

[0023] In terms of functional design, the multi-source power flexible interconnection interface device has the functions of parallel and off-grid conversion module switching, power baseline rolling optimization, multi-objective optimization solution, system margin calculation and control, human-computer interaction, communication and time recording.

[0024] In terms of hardware design, the multi-source power flexible interconnection interface device integrates four DC / DC bidirectional conversion modules, one DC / AC bidirectional conversion module, one intelligent edge terminal and one core controller. The specific hardware design is as follows:

[0025] 1. The DC / DC bidirectional conversion module adopts Buck / Boost bidirectional circuit with high precision and high dynamic response characteristics. The low-voltage DC side voltage range is 48-500V, the peak current is 200A, the high-voltage DC side rated voltage is 700V, and the peak current is 75A.

[0026] 2. The DC / AC bidirectional conversion module adopts three-phase four-bridge arm topology, sine pulse width modulation (SPWM) control mode, and can realize independent control of three-phase and single-phase. The DC side voltage range is 650-900V, the rated current is 75A, the AC side rated power is 50kW, the voltage range is 360-420V, the rated current is 80A, and the power factor is 0.9. The design parameters make the maximum power transmission power of the whole interconnection interface device reach 50kW.

[0027] 3. The hardware composition of the intelligent edge terminal is as shown in Figure 2, each functional board is managed and called by the core board, and data and instructions are exchanged through the bus between modules. The power module converts the external input 24V into the universal power supply required by various types of modules, such as 5V, ±12V, 3.3V, etc.; the basic structure of the intelligent edge terminal that meets the needs of energy management applications is: core (main control) board + functional board + power board, which are connected in a stacked manner. The core board adopts ARM architecture to complete data signal processing, logical operations and other functions, and complete data calculation, control and management of functional modules. The core board supports CAN network, Ethernet, RS485 and 5G and other communication methods, and can realize information transmission of different communication protocols through external connectors. The functional board uses FPGA for logic control, and completes data collection, switch quantity scanning or output control by controlling the extended AD and other peripheral chips, and exchanges data with the core board through the internal bus.

[0028] The intelligent edge terminal and the core controller communicate with each other through the Ethernet port in the external connector, and the 5G gateway in the external connector of the intelligent edge terminal communicates with each other through the Ethernet port in the external connector. Figure 3 The 5G power information network architecture solution in this paper enables long-distance information transmission. The 5G power information network architecture utilizes a cloud-network collaborative management platform. Cloud servers have centralized computing resources and high computing performance, enabling data storage, big data analysis, and prediction. Intelligent edge terminals are used on the edge for coordinated control with the cloud. Their proximity to data sources reduces latency between data production and decision-making, filters out useless data, and reduces transmission bandwidth.

[0029] The core controller's hardware design consists of a main control board, core board, baseboard, and enclosure. The main control board performs analog signal acquisition and conversion, optoelectronic signal input and output conditioning, digital signal acquisition, relay control signal conversion, and other functions. It also provides CAN bus, RS422 bus, and Ethernet interfaces. The core board incorporates the Loongson 2K1000 minimum system and FPGA minimum system. Compared to the core board in intelligent edge terminals, the Loongson 2K1000 can host an operating system to run relevant software and algorithms. The core board utilizes a CPU + FPGA hardware architecture. The CPU serves as the main processor, loading algorithms and controlling the CAN communication interface, RS485 serial communication interface, digital input and output interfaces, memory chips, and Flash chips. The FPGA acts as a coprocessor, responsible for AD chip acquisition and control, fiber optic interface message parsing, and data processing. An 8MB external FLASH memory is used to store programs, a 32MB FLASH memory is used to store algorithm configuration, and a 1GB FLASH memory is used to store recorded data. The CPU and FPGA exchange information through a parallel bus, and the core board and main control board signals exchange through high-speed connectors.

[0030] Regarding information transmission, the intelligent edge terminal collects current, voltage, and power information from the DC / AC and DC / DC bidirectional converter modules through communication. After processing by the core board, the processed information is transmitted to the core controller via Ethernet and uploaded to the cloud-network collaborative management platform via the 5G module. The cloud-network collaborative management platform processes and predicts the data, and the predicted data is transmitted back to the intelligent edge terminal via the 5G network. The intelligent edge terminal then transmits this information to the core controller via Ethernet. After receiving all the information, the core controller outputs relevant control instructions based on the energy management program within the core board. For routine operation information, such as starting, stopping, and setting the DC / AC and DC / DC bidirectional converter modules, the core controller sends this information to the intelligent edge terminal via Ethernet. The intelligent edge terminal then generates logic control instructions through its internal functional boards. Simultaneously, the intelligent edge terminal uploads these operation instructions to the cloud-network collaborative management platform via the 5G module. For emergency stop or shutdown commands, the core controller's main control board directly outputs relay signals to issue shutdown instructions.

[0031] 4. In terms of software design, the energy management of the multi-source power flexible interconnection interface device is configured in the core controller, and the programming language is C language. The software design follows the idea of ​​modularization and interface standardization to facilitate system calls and unified management. The software platform framework is as follows: Figure 4 As shown in the figure, the software is divided into the following layers: bottom-layer driver software, middle-layer functional software and application-layer task software. The bottom-layer software and middle-layer software are encapsulated in a standard format and provide a standard function interface to facilitate system calls and unified management. The multi-source smart power flexible interconnection interface device calls the corresponding task program in the energy management task. The specific functional decomposition is as follows: Figure 5 shown.

[0032] 4.1. On-grid and off-grid conversion mode switching subroutine

[0033] By detecting the on-grid and off-grid status of the multi-source power flexible interconnection interface device, the operating modes of the DC converter and bidirectional converter are actively switched. When the intelligent edge terminal receives a communication signal from the external connector and issues a "grid connection" command, the core controller reads the external command and sends a "constant current mode" command to the DC / AC bidirectional converter. Upon receiving the "constant current mode" command, the DC / AC bidirectional converter's internal phase-locked loop (PLL) continuously reads the phase angle of the grid-connected generator's output waveform. After waiting for 2 seconds, the DC / AC bidirectional converter automatically closes the grid-connection switch based on the phase angle information read by the PLL, completing the grid connection operation. In grid-connected mode, if the core controller receives a mode switch command for the DC converter module, such as "constant current mode" or "constant voltage mode," it outputs a mode switch command to the DC converter module, which then changes its conversion mode.

[0034] When the external connector of the intelligent edge terminal receives the "off-grid" command given by the communication signal, the core controller receives the off-grid command transmitted by the intelligent edge terminal and sends a "constant voltage mode" command to the DC / AC bidirectional converter. The DC / AC bidirectional converter operates in constant voltage mode to realize independent load function.

[0035] 4.2 Power baseline rolling optimization subroutine

[0036] By reading forecast data and power constraint data from the cloud-network collaborative management platform and using the actual operating point of each device at time t as the optimization starting point, the system performs a rolling power optimization solution for M consecutive time periods. This ensures that the operating baselines obtained for each device are predictive and redundant. The first time period of the solution (i.e., the operating point at time t+1) is output as the reference operating point for each converter module at the device layer. At the next time, the rolling optimization program's optimization starting point is updated to time t+1, and the starting point data is updated to the actual operating point of each device at time t+1, before entering the next iteration.

[0037] The optimization solution model is as follows, where the objective function consists of two parts. The first part is the difference between the actual active power output of the diesel generator set and the target value. The second part is the energy storage battery charge and discharge power penalty term. Since the energy storage battery can only be charged or discharged at the same time, to prevent the decision optimization process from showing simultaneous charging and discharging calculation results, this penalty term is added to avoid this scenario. Its coefficient 50 is an adjustable maximum constant and only needs to be set to a value greater than the cost of one energy storage charge and discharge cycle. Here it is set to 50:

[0038]

[0039] sT i G +P i Wd +P i PV +P i DC -P i CH =P i LD

[0040] 0≤P i G ≤P G.max

[0041]

[0042] 0≤P i DC ≤P DC.max

[0043] 0≤P i CH ≤P CH.max

[0044]

[0045] 0≤SOC i ≤1

[0046] Among them, t represents the current time, T represents the total optimization period, the granularity of the period is minute level, P i G represents the active output power of the diesel generator set in the i-th period, which is the decision variable, P i G.A represents the target active output power of the diesel generator set in the i-th period, which is a constant; P i DC Represents the discharge active power of the energy storage battery in the i-th period, which is the decision variable; P i CH Represents the charging active power of the energy storage battery in the i-th period, which is the decision variable; P i Wd represents the output active power of the wind turbine in the i-th period, which is a constant; P i PV represents the output active power of the photovoltaic panel in the i-th period, which is a constant; P i LD It represents the required active power of the load in the i-th period, which is a constant; P G.max Indicates the maximum active power output of the diesel generator set, which is a constant; P G.ramp Indicates the maximum ramp rate / slope rate of the diesel generator set, which is a constant; P DC.max Indicates the maximum discharge power of the energy storage battery, which is a constant; P CH.max Indicates the maximum charging power of the energy storage battery, which is a constant; SOC i Indicates the SOC value of the energy storage battery in the i-th period, which is a decision variable. i-1 is the SOC value of the energy storage battery in the i-1th period, that is, the value of the previous period, which is a constant and can be obtained through the battery management system; σ ch and σ dc = represents the charging and discharging efficiency of the energy storage battery, a constant generally set at 0.9. E represents the rated capacity of the energy storage battery, a constant expressed in kilowatt-hours. The SOC calculation formula includes the constant 1 / 60 because the SOC calculation period is minute-level, while the rated capacity of the energy storage battery is measured in kilowatt-hours, requiring the conversion of hours to minutes for calculation.

[0047] 4.3 Multi-objective optimization solution subroutine

[0048] Based on the external communication signal instructions received by the intelligent edge terminal's external connector, various objective functions are enabled and incorporated into a multi-objective optimization algorithm to generate multi-objective medium- and long-term power consumption results for each device. The economic operation strategy primarily utilizes the energy storage battery to compensate for the discrepancy between wind and photovoltaic power generation and load power consumption. The diesel generator sets make up the shortfall, or a power cut-off action is taken to balance the power gap. When the battery SOC is below 0.2 or above 0.8, the economic operation strategy limits the battery charge and discharge current to extend battery life. The high-performance operation strategy primarily relies on the diesel generator sets and energy storage to jointly support the load. The diesel generator sets operate within the economic range to maintain high diesel combustion efficiency, while the energy storage batteries compensate for any remaining power imbalance. The safe operation strategy primarily relies on the diesel generator sets to support the majority of the load, with the energy storage batteries compensating for any remaining power imbalance.

[0049] 4.4 System Margin Calculation and Control Subroutine

[0050] Based on the operating status of the power generation equipment, power load data information, and taking into account the random output factors of wind power, photovoltaic power, and load, the system's adjustable capacity value for a period of time in the future is calculated and compared with the demand regulation capacity. When the system's adjustable capacity is lower than the demand regulation capacity, the grid-connected equipment or load is cut off step by step according to the weight level.

[0051] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A control method for a multi-source power flexible interconnection interface device, characterized in that: By detecting the on-grid and off-grid status of the multi-source power flexible interconnection interface device, the operating modes of the DC converter and bidirectional converter are actively switched. When the core controller reads the grid-connection command from the intelligent edge terminal, it sends a "constant current mode" command to the DC / AC bidirectional converter. After receiving the "constant current mode" command, the phase-locked loop (PLL) in the DC / AC bidirectional converter constantly reads the output waveform phase angle of the grid-connected generator set. After waiting for 2 seconds, the DC / AC bidirectional converter automatically closes the grid-connection switch based on the phase angle information read by the PLL, completing the grid connection operation. In the grid-connected mode, if the core controller receives a mode switching instruction for the DC converter module, it outputs a mode switching instruction to the DC converter module, and the DC converter module immediately changes the conversion mode; After receiving the instruction from the intelligent edge terminal, the core controller sends a "constant voltage mode" instruction to the DC / AC bidirectional converter. The DC / AC bidirectional converter operates in constant voltage mode and achieves independent load carrying. By reading the forecast data and power constraint data from the cloud network collaborative management platform, and using the current t The actual operating point of each device at any time is used as the optimization starting point, and continuous M The power baseline rolling optimization solution of each period is used to make the obtained operating baseline of each device predictable and redundant, and the operating result of the first period in the solution is output as the reference operating point of each layer of power conversion module; After entering the next moment, the optimization starting point of the power baseline rolling optimization will be updated to t +1 time, the starting point data will be updated to t +1 is the actual operating point of each device, and the next iteration begins; The objective function of the power baseline rolling optimization includes two parts: the first part is the difference between the actual active power output of the diesel generator set and the target value; the second part is the penalty term for the charging and discharging power of the energy storage battery to prevent simultaneous charging and discharging during the decision optimization process.

2. A multi-source power flexible interconnection interface device, characterized in that: The multi-source power flexible interconnection interface device is controlled using the control method of claim 1, wherein the device includes four DC / DC bidirectional conversion modules, one bidirectional DC / AC conversion module, an intelligent edge terminal and a core controller; The diesel generator set is connected to a 700V DC bus through a bidirectional DC / AC converter module. The DC bus is then connected to energy storage batteries, supercapacitors, wind turbines, and photovoltaic panels through four DC / DC bidirectional converter modules. The intelligent edge terminal collects and processes the current, voltage, and power of the DC / AC bidirectional conversion module and the DC / DC bidirectional conversion module in the form of communication. On the one hand, it transmits the processed information to the core controller via Ethernet, and on the other hand, it uploads it to the cloud-network collaborative management platform via the 5G module. The cloud-network collaborative management platform processes and predicts the data, and the predicted data is transmitted back to the intelligent edge terminal via the 5G network. The intelligent edge terminal then transmits the information to the core controller via Ethernet. After receiving all the information, the core controller outputs operation control instructions to the DC / AC bidirectional conversion module and the DC / DC bidirectional conversion module. At the same time, the core controller sends all the information to the intelligent edge terminal via Ethernet. The intelligent edge terminal then outputs logic control instructions. At the same time, the intelligent edge terminal uploads all instructions to the cloud-network collaborative management platform via the 5G module. The intelligent edge terminal and core controller control four DC / DC bidirectional conversion modules and one bidirectional DC / AC conversion module to work together to achieve on-grid and off-grid operation of multiple new energy sources such as energy storage batteries, supercapacitors, wind power and photovoltaics.

3. The multi-source power flexible interconnection interface device according to claim 2, characterized in that: The intelligent edge terminal and the core controller communicate with each other through the Ethernet port in the external connector.

4. The multi-source power flexible interconnection interface device according to claim 2 or 3, characterized in that: The 5G gateway in the external connector of the intelligent edge terminal realizes long-distance transmission of information through the 5G power information network architecture.

5. The multi-source power flexible interconnection interface device according to claim 4, characterized in that: The 5G power information network architecture adopts a cloud-network collaborative management platform architecture, in which cloud servers are used to realize data storage and big data analysis and prediction; the edge side adopts intelligent edge terminals to coordinate and regulate with cloud servers. It is close to the data source, reducing the delay between data production and decision-making, filtering out useless data, and reducing transmission bandwidth.

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