Five-port isolation type electric energy router

Abstract

The utility model discloses a five-port isolation type electric energy router. The electric energy router comprises a photovoltaic port, an energy storage port, a DC load port, a single-phase AC load port, a grid-connected port, a bidirectional DC / DC converter, an AC / DC converter and a dual active bridge isolation module. The photovoltaic port is connected with the photovoltaic module and a direct-current bus of the electric energy router through the bidirectional DC / DC converter, the energy storage port is connected with the energy storage battery and a direct-current bus of the electric energy router through the bidirectional DC / DC converter, and the direct-current load port is connected with a direct-current load and a direct-current bus of the electric energy router through the bidirectional DC / DC converter. The single-phase AC load port is connected with the single-phase AC load and the DC bus of the electric energy router through the AC / DC converter, and the grid-connected port is connected with the low-voltage power distribution network and the DC bus of the electric energy router through the AC / DC converter; the DC bus is connected to the dual-active bridge isolation module.

Description

Technical Field

[0001] The utility model belongs to the technical field of isolated power routers, and in particular relates to a 5-port isolated power router. Background Art

[0002] As global energy shortages and environmental pollution become increasingly prominent, scholars around the world have proposed building a new energy interconnection architecture—the Energy Internet. Electrical energy routers (EERs), as an organic combination of power electronics and information technology, provide flexible connectivity for AC power grids, energy storage devices, distributed power sources, and distributed loads. They are key components in building the Energy Internet. The five-port isolated EER, in particular, features multiple ports and electrical isolation that better adapt to the diverse energy flow and management requirements of the Energy Internet.

[0003] However, with the integration of distributed energy resources, microgrid flows are becoming more diverse. The new source-grid-load-storage relationship of the Energy Internet places higher demands on power routers. Traditional five-port isolated power routers, due to their use of power frequency isolation, suffer from bulky design and high losses, making them inadequate for current development trends. Therefore, optimizing traditional power routers and achieving stable DC bus voltage control in both on-grid and off-grid operating modes based on their architecture and port characteristics remains a challenge. Utility Model Content

[0004] The present invention aims to solve the deficiencies of the prior art and provides the following solutions:

[0005] A 5-port isolated power router, comprising: a photovoltaic port, an energy storage port, a DC load port, a single-phase AC load port, a grid-connected port, several bidirectional DC / DC converters, several AC / DC converters, and a dual active bridge isolation module;

[0006] The photovoltaic port connects the photovoltaic component to the DC bus of the power router through the bidirectional DC / DC converter, the energy storage port connects the energy storage battery to the DC bus of the power router through the bidirectional DC / DC converter, the DC load port connects the DC load to the DC bus of the power router through the bidirectional DC / DC converter, the single-phase AC load port connects the single-phase AC load to the DC bus of the power router through the AC / DC converter, and the grid-connected port connects the low-voltage distribution network to the DC bus of the power router through the AC / DC converter; the DC bus is connected to the dual active bridge isolation module.

[0007] Preferably, the photovoltaic component adopts a YXPVS photovoltaic cell array simulator with an output voltage of 800V / 1000V and a maximum power of 15KW.

[0008] Preferably, the energy storage battery adopts a YXDG-DBG high-precision bidirectional energy storage battery simulator with a DC voltage of 0-800V and a DC current of 0-40A.

[0009] Preferably, the DC load adopts a YXDG-RLD resistive DC load with a voltage range of 0-400V, a current range of 0-100A, and a power range of 0-10kW.

[0010] Preferably, the single-phase AC load adopts a YXAC-EL single-phase AC electronic load with a voltage range of 0-400V, a current range of 0-100A, and a power range of 0-10kW.

[0011] Preferably, the AC / DC converter used in the grid connection adopts YXSG-17KTL photovoltaic inverter, with a maximum input power of 7-18kW, a maximum input voltage of 1000V, a rated DC voltage of 620V, a frequency of 50 / 60Hz, a power factor of 0.99, and a total harmonic distortion of less than 3%.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] This utility model analyzes the basic functional requirements of an energy router and establishes a basic topology architecture of a 5-port isolated energy router. The energy storage port can adapt to changes in photovoltaic output and load fluctuations, improving the adaptability and reliability of the system. The proposed dual-mode control method achieves stable control of the DC bus voltage in the off-grid mode, reduces energy loss, and improves the reliability and economy of the power grid. It provides a reference for the practical application of the topology of the energy router and the coordinated control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0015] Figure 1 This is a schematic diagram of the structure of the power router according to an embodiment of the present utility model;

[0016] Figure 2 This is a dual-mode operation control strategy of an embodiment of the present utility model, wherein (a) is a grid-connected mode control strategy, and (b) is an off-grid mode control strategy;

[0017] Figure 3 The grid-connected mode experimental waveforms of the embodiment of the present invention, where (a) is the voltage and current waveforms, and (b) is the DC bus voltage and power waveforms;

[0018] Figure 4 The off-grid mode experimental waveforms of the embodiment of the present invention, where (a) is the voltage and current waveforms, and (b) is the DC bus voltage and power waveforms;

[0019] Description of reference numerals:

[0020] 1. Photovoltaic module; 2. Photovoltaic port; 3. Bidirectional DC / DC converter; 4. Dual active bridge isolation module; 5. AC / DC converter; 6. Grid-connected port; 7. Low-voltage distribution network; 8. Energy storage battery; 9. Energy storage port; 10. DC load port; 11. Single-phase AC load port. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0023] Example 1

[0024] In this embodiment, if Figure 1 As shown, a 5-port isolated power router includes: a photovoltaic port 2, an energy storage port 9, a DC load port 10, a single-phase AC load port 11, a grid-connected port 6, several bidirectional DC / DC converters 3, several AC / DC converters 5 and a dual active bridge isolation module 4.

[0025] The photovoltaic port 2 connects the photovoltaic module 1 to the DC bus of the power router through a bidirectional DC / DC converter 3. The energy storage port 9 connects the energy storage battery 8 to the DC bus of the power router through a bidirectional DC / DC converter 3. The DC load port 10 connects the DC load to the DC bus of the power router through a bidirectional DC / DC converter 3. The single-phase AC load port 11 connects the single-phase AC load to the DC bus of the power router through an AC / DC converter 5. The grid-connected port 6 connects the external 380V low-voltage distribution network 7 to the DC bus of the power router through an AC / DC converter 5. The grid-connected port 6 uses a PWM rectifier to convert the form and voltage level of electrical energy. The DC bus is connected to a dual active bridge isolation module 4, which is used for electrical isolation between the 750V high-voltage DC bus and the grid, so that each part is interconnected through the high-voltage common DC bus and the control is relatively independent.

[0026] In this embodiment, the photovoltaic module 1 adopts the YXPVS photovoltaic cell array simulator, with an output voltage of up to 800V or 1000V and a maximum power of up to 15KW; the energy storage battery 8 adopts the YXDG-DBG high-precision bidirectional energy storage battery simulator, with a DC voltage of 0-800V and a DC current of 0-40A; the DC load adopts the YXDG-RLD resistive DC programmable load, with a voltage range of 0-400V, a current range of 0-100A, and a power range of 0-10kW The single-phase AC load adopts the YXAC-EL single-phase AC electronic load with a voltage range of 0-400V, a current range of 0-100A, and a power range of 0-10kW; the AC / DC converter 5 used for grid connection adopts the YXSG-17KTL photovoltaic inverter with a maximum input power of 7-18kW, a maximum input voltage of 1000V, a rated DC voltage of 620V, a frequency of 50 / 60Hz, a power factor of 0.99, and a total harmonic distortion (THDi) of less than 3%.

[0027] Example 2

[0028] In this embodiment, if Figure 2 As shown in the figure, a dual-mode operation control method for a 5-port isolated power router is provided. The voltage and current of the five ports are monitored in real time. Based on the voltage and current changes, different control strategies are used to dynamically adjust the power flow and stabilize the DC bus voltage.

[0029] The dual-mode operation control method adopts maximum power point tracking control based on the disturbance observation method for photovoltaic port 2, and controls the duty cycle of the bidirectional DC / DC converter 3 by generating adjustment instructions to achieve effective control of the DC side voltage of the photovoltaic cell.

[0030] like Figure 2As shown in (a), in the grid-connected mode: a dual-loop control strategy of a DC voltage outer loop and an inductor current inner loop is adopted. The grid-connected energy storage adopts constant power control, and the grid-connected inverter adopts constant voltage control. The power generated by the photovoltaic module 1 is preferentially supplied to the DC load and the single-phase AC load, and then returned to the low-voltage distribution network 7. The remaining power is used to charge the energy storage battery 8.

[0031] The dual-loop control strategy involves detecting the difference between the DC bus reference voltage and actual voltage through an outer DC voltage control loop. A PI controller generates a reference value for the inductor current in the inner loop, achieving DC-side voltage stabilization control for the PWM rectifier. In this scenario, the grid-connected energy storage is controlled at a constant power level, while the grid-connected inverter is controlled at a constant voltage level. The photovoltaic system is connected to the DC bus in MPPT mode. Power generated is first supplied to the load and then returned to the grid, with the remainder used to charge the energy storage. When the SOC is greater than 90% or less than 20%, the energy storage enters standby mode.

[0032] like Figure 2 As shown in (b), in off-grid mode: the energy storage port 9 stabilizes the voltage of the DC bus in voltage control mode, generates electricity through the photovoltaic module 1, and the energy storage battery 8 transmits power to the DC load and the single-phase AC load, so that the power sharing of the power supply, load and energy storage is in a balanced state.

[0033] Achieving a balanced state of power supply and demand includes: when the power generated by the photovoltaic module 1 is greater than the power consumed by the DC load and the single-phase AC load, the voltage of the DC bus is higher than the reference value, and the energy storage battery 8 consumes the power generated by the photovoltaic module 1; when the power generated by the photovoltaic module 1 is less than the power consumed by the DC load and the single-phase AC load, the voltage of the DC bus is lower than the reference value, and the energy storage battery 8 generates power.

[0034] Example 3

[0035] In this embodiment, a physical prototype is built.

[0036] This prototype consists of a three-phase voltage source inverter, a single-phase inverter, a boost converter, a buck / boost converter, and a DAB converter. Its port voltages are 400V, 300V, 380V, 220V, and 400V, with capacities of 15kW, 10kW, 15kW, 5kW, and 10kW. The intermediate DAB isolation stage provides electrical isolation between components, ensuring system safety and reliability. Key parameters of the power router prototype are shown in Table 1.

[0037] Table 1

[0038]

[0039] The prototype power router's control system hardware uses TI's TMS320C6747 as the main control board CPU and an FPGA as the auxiliary CPU. The TMS320C6747 is primarily used for algorithm implementation, while the FPGA handles ADC acquisition, PWM output, and DO output functions.

[0040] In order to verify the correctness of the design method of this utility model and the effectiveness of the control strategy, the developed prototype was brought into the off-grid and grid-connected working conditions for functional testing. The two experimental working conditions are shown in Table 2.

[0041] Table 2

[0042]

[0043] Prototype experiment 1: grid-connected mode.

[0044] Figure 3 Middle (a) / Figure 3 Figure (b) shows the experimental waveform of the Energy Router in grid-connected mode. Initially, all PV power goes to charging the energy storage, and the DC bus voltage stabilizes at 750V. After a 0.9kW single-phase AC load is added at t1, the PV prioritizes powering the load, leaving the remaining 1.2kW to charge the energy storage. At t2, the single-phase AC load increases to 2.6kW, with the energy storage and PV power supplying the load together. At t3, the PV is disconnected. Due to the energy storage discharge power limit and the power loss of the switching power supply, 0.8kW of power is drawn from the grid, with the energy storage and grid powering the load together. The DC bus voltage briefly dips before quickly recovering. The waveform is relatively stable, meeting power quality requirements, demonstrating that the prototype achieves its basic design functionality in grid-connected mode. The THD of each electrical quantity in the experiment is shown in Table 3, and the power control accuracy of each port at each stage is shown in Table 4.

[0045] Table 3

[0046]

[0047] Table 4

[0048]

[0049] It can be seen from Tables 3 and 4 that the control accuracy is high, which verifies the effectiveness and accuracy of the coordinated control strategy in the grid-connected mode.

[0050] Prototype experiment 2: off-grid mode.

[0051] Figure 4 Middle (a) / Figure 4Figure (b) shows the waveform of the off-grid mode experiment for the Energy Router. After the PV system is added at t1, all PV power goes to the energy storage system. At t2, a 0.8kW DC load is added, with the PV system prioritizing the load, while the remaining 1.3kW goes to the energy storage system. At t3, the DC load is increased to 4kW, with both the energy storage system and the PV system providing power to the load. The THD values ​​for each electrical quantity in the experiment are shown in Table 5, and the power control accuracy for each port at each stage is shown in Table 6. This demonstrates that the design requirements are met under these conditions, verifying the effectiveness of the coordinated control strategy in off-grid mode and the correctness of the Energy Router design approach.

[0052] Table 5

[0053]

[0054] Table 6

[0055]

[0056] In summary, the prototype has achieved the basic functions of the design in both off-grid and grid-connected modes with high control accuracy, verifying the correctness of the design method of the 5-port isolated power router and the effectiveness of the dual-mode control method.

[0057] The embodiments described above are merely descriptions of preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A 5-port isolated power router, characterized in that: include: Photovoltaic port, energy storage port, DC load port, single-phase AC load port, grid-connected port, several bidirectional DC / DC converters, several AC / DC converters and dual active bridge isolation modules; The photovoltaic port connects the photovoltaic component to the DC bus of the power router through the bidirectional DC / DC converter, the energy storage port connects the energy storage battery to the DC bus of the power router through the bidirectional DC / DC converter, the DC load port connects the DC load to the DC bus of the power router through the bidirectional DC / DC converter, the single-phase AC load port connects the single-phase AC load to the DC bus of the power router through the AC / DC converter, and the grid-connected port connects the low-voltage distribution network to the DC bus of the power router through the AC / DC converter; the DC bus is connected to the dual active bridge isolation module.

2. A 5-port isolated power router according to claim 1, characterized in that: The photovoltaic module adopts a YXPVS photovoltaic cell array simulator with an output voltage of 800V / 1000V and a maximum power of 15KW.

3. The 5-port isolated power router according to claim 1, characterized in that: The energy storage battery adopts the YXDG-DBG high-precision bidirectional energy storage battery simulator with a DC voltage of 0-800V and a DC current of 0-40A.

4. The 5-port isolated power router according to claim 1, characterized in that: The DC load adopts a YXDG-RLD resistive DC load with a voltage range of 0-400V, a current range of 0-100A, and a power range of 0-10kW.

5. The 5-port isolated power router according to claim 1, characterized in that: The single-phase AC load adopts YXAC-EL single-phase AC electronic load with a voltage range of 0-400V, a current range of 0-100A, and a power range of 0-10kW.

6. The 5-port isolated power router according to claim 1, characterized in that: The AC / DC converter used in the grid connection adopts YXSG-17KTL photovoltaic inverter, with a maximum input power of 7-18kW, a maximum input voltage of 1000V, a rated DC voltage of 620V, a frequency of 50 / 60Hz, a power factor of 0.99, and a total harmonic distortion of less than 3%.

Images