Three-phase unbalance treatment system and method for light storage power supply and dynamic power regulation
The three-phase imbalance management system, which combines photovoltaic power supply and dynamic power regulation, dynamically adjusts the inverter output power, solving the problem of three-phase imbalance in the low-voltage distribution network and improving power quality and grid-connected power generation efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENYANG AGRI UNIV
- Filing Date
- 2022-08-04
- Publication Date
- 2026-05-12
AI Technical Summary
In low-voltage distribution networks, the increase in load demand and the access of single-phase distributed photovoltaic power have led to three-phase imbalance problems, which affect voltage quality and grid-connected power generation efficiency. Existing measures have problems such as large investment, commutation failure and negative impacts.
A three-phase imbalance control system employing photovoltaic-storage power supply and dynamic power regulation achieves three-phase power balance by installing current and voltage transmitters at the grid connection point and load side, combined with a PLC and inverter system, to dynamically adjust the inverter output power.
It has improved the capacity for renewable energy absorption, enhanced power quality, reduced energy consumption, and solved the power grid operation safety problem caused by three-phase imbalance.
Smart Images
Figure CN115189374B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a grid-connected three-phase imbalance management system and method, and more particularly to a photovoltaic-storage power supply and dynamic power regulation three-phase imbalance management system and method. Background Technology
[0002] my country's low-voltage distribution network (LVDN) adopts a three-phase four-wire wiring system. Due to imperfect LVDN management and a lack of forward-looking planning, problems such as parameter asymmetry and three-phase load imbalance exist. With the improvement of people's living standards, load demand is gradually increasing, and the widespread integration of single-phase distributed photovoltaic systems further exacerbates the three-phase imbalance of LVDN, posing numerous challenges to voltage quality and line loss management in the distribution network, and even affecting the operational safety of LVDN. Currently, the corresponding measures to address the three-phase imbalance of LVDN can be divided into two categories. One type of measure is load-side control, which uses algorithms to allocate phase sequence and combines it with commutation devices to achieve uniform load distribution. However, low-voltage distribution areas have numerous loads, but require a large number of commutation switches, resulting in high investment. In addition, voltage flicker is inevitable during the commutation process, and commutation failure will also cause load outages, negatively impacting user equipment and the power experience. Another type of measure is system-side control, which mainly involves coordinating and controlling the LVDN through methods such as on-load tap-changing transformer regulation, load reconfiguration, and power control of photovoltaic inverters.
[0003] The grid connection efficiency of photovoltaic power generation units reaches its maximum when the three-phase load is balanced, that is, the generated power is injected into the grid in a balanced three-phase power. However, when the three-phase load is unbalanced, the grid connection efficiency is reduced because the system capacity cannot be fully utilized by the photovoltaic power generation units due to the existence of power exchange. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a three-phase imbalance management system and method for photovoltaic power supply and dynamic power regulation. The aim is to improve the three-phase load imbalance of low-voltage power grids by using independently controllable grid-connected power injection for each phase.
[0005] To achieve the above objectives, the present invention provides a three-phase imbalance control system for photovoltaic power supply and dynamic power regulation. Current transmitters are installed on the live wires of both the grid side and the load side at the grid connection point, and voltage transmitters are installed on the live wires of the load side. Two current transmitters and one voltage transmitter on each live wire are connected to an analog-to-digital converter (ADC). The ADC is connected to a PLC, which is connected to an inverter system via an RS485 hub. The inverter system output is connected to the live wire, and the inverter system input is connected to a photovoltaic cell charging controller. The photovoltaic cell charging controller is connected to the battery and the photovoltaic panel.
[0006] The inverter system includes an A-phase inverter, a B-phase inverter, and a C-phase inverter. The output terminals of the A-phase inverter, the B-phase inverter, and the C-phase inverter are respectively connected to the first AC contactor and then connected to the grid connection point. The control coil input terminal of the first AC contactor is connected to the PLC.
[0007] The photovoltaic cell charging controller is provided with a second AC contactor between itself and the photovoltaic panel, and the control coil input terminal of the second AC contactor is connected to the PLC.
[0008] The photovoltaic cell charging controller is provided with a third AC contactor between itself and the battery, and the control coil input terminal of the third AC contactor is connected to the PLC.
[0009] A fourth AC contactor is provided between the photovoltaic cell charging controller and the inverter system, and the control coil input terminal of the fourth AC contactor is connected to the PLC.
[0010] The PLC model mentioned is FX3U48MR.
[0011] The A-phase live wire is equipped with a first current transmitter and a fourth current transmitter; the B-phase live wire is equipped with a second current transmitter and a fifth current transmitter; and the C-phase live wire is equipped with a third current transmitter and a sixth current transmitter. The first and fourth current transmitters are connected to a first analog-to-digital converter (ADC); the second and fifth current transmitters are connected to a second ADC; the third and sixth current transmitters are connected to a third ADC; the first ADC is connected to a third voltage transmitter; the third voltage transmitter is connected to the A-phase live wire on the load side; the second ADC is connected to a second voltage transmitter; the second voltage transmitter is connected to the B-phase live wire on the load side; the third ADC is connected to the first voltage transmitter; and the first voltage transmitter is connected to the C-phase live wire on the load side.
[0012] The method for managing three-phase imbalance in a photovoltaic-storage power supply and dynamic power regulation system involves voltage and current transmitters transmitting the three-phase voltage at the grid connection point, the three-phase current on the grid side, and the three-phase current on the load side to the PLC via analog-to-digital conversion. This yields the three-phase power on the grid side, the three-phase power on the load side, and their respective load imbalances at the grid connection point. The PLC determines whether the load-side three-phase power imbalance exceeds a set value. If the load-side three-phase power imbalance is less than the set value, the photovoltaic grid-connected mode is activated for balanced distribution of three-phase output power. The PLC sends data to the inverter system to change the inverter output power, with all three inverters simultaneously supplying the same power to the grid, which is one-third of the photovoltaic cell capacity. If the load-side three-phase power imbalance exceeds the set value, the system checks whether the grid-side imbalance exceeds the set value. If it is less, the system has achieved optimal three-phase power balance, and maintaining the grid connection status and output power of each DC power source and inverter is sufficient. If the grid-side imbalance exceeds the set value, the system remains unbalanced, and the output power is adjusted accordingly.
[0013] After the three inverters simultaneously supply the same power to the grid, they wait for a timer to trigger the next PLC check to determine whether the three-phase power imbalance on the load side is greater than the set value.
[0014] When the grid-side imbalance exceeds a set value, first determine the phase with the highest power, the intermediate phase, and the lowest power on the load side. The phase with the highest power on the load side is phase α, the intermediate phase is phase β, and the lowest power phase is phase γ. Then, the inverter that outputs power to the phase with the highest power is the phase α inverter, the inverter that outputs power to the intermediate phase is the phase β inverter, and the inverter that outputs power to the phase with the lowest power is the phase γ inverter. Calculate δ = the difference between phase α and phase β; ε = the difference between phase α and phase γ; ζ = the difference between phase β and phase γ.
[0015] If δ≥S, that is, the difference between the maximum phase power and the intermediate phase power on the load side is greater than or equal to the photovoltaic cell capacity, the PLC sends data to the inverter to change the output power of the α phase inverter to the photovoltaic cell capacity, and the inverter power of the β phase inverter and γ phase inverter is 0.
[0016] If δ < S, that is, the difference between the maximum phase power and the intermediate phase power is less than the photovoltaic cell capacity, determine the magnitude of ε + ζ and S;
[0017] If ε+ζ≥S, the PLC sends data to the inverter to change the inverter power of the α-phase inverter to δ. Then the remaining available capacity is RES1=S-δ. The PLC sends data to the inverter to distribute the remaining available capacity RES1 equally to the α-phase inverter and the β-phase inverter. That is, the α-phase inverter is δ+RES1 / 2, the β-phase inverter is RES1 / 2, and the γ-phase inverter is 0.
[0018] If ε+ζ<S, the PLC sends data to the inverter to change the output power of the β-phase inverter to ζ and the inverter power of the α-phase inverter to ε. Then the remaining available capacity is RES1=S-(ε+ζ). The PLC sends data to the inverter to distribute the remaining available capacity RES1 equally among the A-phase inverter, B-phase inverter and C-phase inverter, that is, each phase increases the inverter power by RES1 / 3. That is, the α-phase inverter is ε+RES1 / 3, the β-phase inverter is ζ+RES1 / 3 and the γ-phase inverter is RES1 / 3.
[0019] Advantages and effects of the present invention: The present invention solves the problem of three-phase load imbalance in the distribution network. While the distributed photovoltaic power source is connected to the grid for power generation, it dynamically adapts to the three-phase unbalanced load and independently controls the output power of each phase of the photovoltaic system to compensate for and manage the three-phase unbalanced load, improve the renewable energy absorption capacity and the flexibility and economic operation of the photovoltaic system, and achieve the purpose of improving power quality and reducing energy consumption. Attached Figure Description
[0020] Figure 1 This is a flowchart of the present invention.
[0021] Figure 2 This is a schematic diagram of the electrical connections of the present invention.
[0022] Figure 3 This is a schematic diagram of the connection between the PLC and RS485 of this invention.
[0023] In the diagram: 1. PLC; 2. RS485 hub; 3. Inverter system; 31. Phase A inverter; 32. Phase B inverter; 33. Phase C inverter; 4. Photovoltaic cell charging controller; 5. Battery; 6. Photovoltaic panel; 7. First current transmitter; 8. Second current transmitter; 9. Third current transmitter; 10. Fourth current transmitter; 11. Fifth current transmitter; 12. Sixth current transmitter; 13. Third analog-to-digital converter; 14. Second analog-to-digital converter; 15. First analog-to-digital converter; 16. Third voltage transmitter; 17. Second voltage transmitter; 18. First voltage transmitter; 19. Touch screen display; 20. Control buttons; 21. Indicator light; KM0, First AC contactor; KM1, Second AC contactor; KM2, Third AC contactor; KM3, Fourth AC contactor. Detailed Implementation
[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] like Figure 2-3 As shown, the three-phase imbalance control system for photovoltaic power supply and dynamic power regulation of the present invention has current transmitters installed on the live wires on the grid side and load side at the grid connection point, and voltage transmitters installed on the live wires on the load side. The two current transmitters and voltage transmitters on each live wire are connected to an analog-to-digital converter. The analog-to-digital converter is connected to a PLC1. The PLC1 is connected to the inverter system 3 through an RS485 hub 2. The output terminal of the inverter system 3 is connected to the live wire, and the input terminal of the inverter system 3 is connected to the photovoltaic cell charging controller 4. The photovoltaic cell charging controller 4 is connected to the storage battery 5 and the photovoltaic panel 6.
[0026] The inverter system 3 includes an A-phase inverter 31, a B-phase inverter 32, and a C-phase inverter 33. The output terminals of the A-phase inverter 31, B-phase inverter 32, and C-phase inverter 33 are respectively connected to the first AC contactor KM0 and then connected to the grid connection point. The control coil input terminal of the first AC contactor KM0 is connected to PLC1. The A-phase inverter 31, B-phase inverter 32, and C-phase inverter 33 are respectively connected to the neutral line to form a circuit.
[0027] A second AC contactor KM1 is provided between the photovoltaic cell charging controller 4 and the photovoltaic panel 6, and the control coil input terminal of the second AC contactor KM1 is connected to the PLC1.
[0028] A third AC contactor KM2 is provided between the photovoltaic cell charging controller 4 and the storage battery 5. The control coil input terminal of the third AC contactor KM2 is connected to the PLC1.
[0029] A fourth AC contactor KM3 is provided between the photovoltaic cell charging controller 4 and the inverter system 3. The control coil input terminal of the fourth AC contactor KM3 is connected to the PLC1.
[0030] The PLC1 is model FX3U48MR, and the RS485 hub 2 is an opto-isolated RS485 hub. The RS485 hub 2 is connected to a touch screen display 19, which is a Mitsubishi GS2107-WTBD series. The PLC1 is connected to two control buttons 20 and six indicator lights 21 for starting and stopping the equipment, displaying the system's operating status and fault indication. When operating normally, the screen displays the operating parameters and status of each device, and the corresponding status indicator lights up. When an abnormal accident occurs, operation stops, the screen displays the fault location, and the corresponding fault indicator lights up.
[0031] The A-phase live wire is equipped with a first current transmitter 7 and a fourth current transmitter 10; the B-phase live wire is equipped with a second current transmitter 8 and a fifth current transmitter 11; and the C-phase live wire is equipped with a third current transmitter 9 and a sixth current transmitter 12. The first current transmitter 7 and the fourth current transmitter 10 are connected to a first analog-to-digital converter 15; the second current transmitter 8 and the fifth current transmitter 11 are connected to a second analog-to-digital converter 14; the third current transmitter 9 and the sixth current transmitter 12 are connected to a third analog-to-digital converter 13; the first analog-to-digital converter 15 is connected to a third voltage transmitter 16; the third voltage transmitter 16 is connected to the A-phase live wire on the load side; the second analog-to-digital converter 14 is connected to a second voltage transmitter 17; the second voltage transmitter 17 is connected to the B-phase live wire on the load side; the third analog-to-digital converter 13 is connected to a first voltage transmitter 18; and the first voltage transmitter 18 is connected to the C-phase live wire on the load side.
[0032] like Figure 1 As shown, the method for managing the three-phase imbalance of photovoltaic-storage power supply and dynamic power regulation system involves voltage and current transmitters transmitting the three-phase voltage at the grid connection point, the three-phase current on the grid side, and the three-phase current on the load side to the PLC via analog-to-digital conversion. This yields the three-phase power on the grid side at the grid connection point, the three-phase power on the load side, and their respective load imbalance degrees. Here, A represents the A-phase power on the load side at the grid connection point, B represents the B-phase power on the load side at the grid connection point, C represents the C-phase power on the load side at the grid connection point, X represents the A-phase power on the grid side at the grid connection point, Y represents the B-phase power on the grid side at the grid connection point, C represents the C-phase power on the grid side at the grid connection point, U represents the three-phase imbalance degree on the load side, and W represents the three-phase imbalance degree on the grid side.
[0033] The PLC determines whether the three-phase power imbalance on the load side is greater than a set value. If the load-side three-phase power imbalance is less than the set value, the photovoltaic grid-connected mode is activated for balanced distribution of three-phase output power. The PLC sends data to the inverter system to change the inverter output power, and all three inverters simultaneously supply the same power to the grid, which is one-third of the photovoltaic cell capacity. If the load-side three-phase power imbalance is greater than the set value, the PLC determines whether the grid-side imbalance is greater than the set value. If it is less, it means that the system has now achieved optimal three-phase power balance, and it is sufficient to maintain the grid-connected status and output power of each DC power supply and inverter. If the grid-side imbalance is greater than the set value, it means that the system is still unbalanced, and the output power is adjusted. After adjustment, a timer is set for 1 minute to wait for the next PLC determination of whether the load-side three-phase power imbalance is greater than the set value.
[0034] After the three inverters simultaneously supply the same power to the grid, they wait for a timer of 30 seconds before entering the next PLC cycle to determine whether the three-phase power imbalance on the load side is greater than the set value.
[0035] When the grid-side imbalance exceeds a set value, first determine the phase with the highest power, the intermediate phase, and the lowest power on the load side. The phase with the highest power on the load side is phase α, the intermediate phase is phase β, and the lowest power phase is phase γ. Then, the inverter that outputs power to the phase with the highest power is the phase α inverter, the inverter that outputs power to the intermediate phase is the phase β inverter, and the inverter that outputs power to the phase with the lowest power is the phase γ inverter. Calculate δ = the difference between phase α and phase β; ε = the difference between phase α and phase γ; ζ = the difference between phase β and phase γ.
[0036] If δ≥S, that is, the difference between the maximum phase power and the intermediate phase power on the load side is greater than or equal to the photovoltaic cell capacity, the PLC sends data to the inverter to change the output power of the α phase inverter to the photovoltaic cell capacity, and the inverter power of the β phase inverter and γ phase inverter is 0.
[0037] If δ < S, that is, the difference between the maximum phase power and the intermediate phase power is less than the photovoltaic cell capacity, determine the magnitude of ε + ζ and S;
[0038] If ε+ζ≥S, the PLC sends data to the inverter to change the inverter power of the α-phase inverter to δ. Then the remaining available capacity is RES1=S-δ. The PLC sends data to the inverter to distribute the remaining available capacity RES1 equally to the α-phase inverter and the β-phase inverter. That is, the α-phase inverter is δ+RES1 / 2, the β-phase inverter is RES1 / 2, and the γ-phase inverter is 0.
[0039] If ε+ζ<S, the PLC sends data to the inverter to change the output power of the β-phase inverter to ζ and the inverter power of the α-phase inverter to ε. Then the remaining available capacity is RES1=S-(ε+ζ). The PLC sends data to the inverter to distribute the remaining available capacity RES1 equally among the A-phase inverter, B-phase inverter and C-phase inverter, that is, each phase increases the inverter power by RES1 / 3. That is, the α-phase inverter is ε+RES1 / 3, the β-phase inverter is ζ+RES1 / 3 and the γ-phase inverter is RES1 / 3.
[0040] The working principle of this invention is as follows: In the initial planning of a three-phase four-wire low-voltage distribution network, designers typically design it based on the assumption that each phase carries a roughly equal amount of single-phase load. Although the randomness of the load during operation leads to three-phase imbalance, within the allowable range, this imbalance does not significantly impact the operation of the power grid. Therefore, by incorporating a start-up criterion into the control strategy of the photovoltaic-storage grid-connected system during actual operation, adjustments can be made when the three-phase load imbalance exceeds the allowable range, while within the allowable range, the photovoltaic power generation units can generate electricity at a high efficiency when connected to the grid.
[0041] In rural low-voltage distribution networks with three-phase four-wire systems, the imbalance of three-phase current is more prominent than the imbalance of three-phase voltage. Due to factors such as the randomness of the load, the asymmetry of the three phases, the asymmetry of power line parameters, and the access of single-phase grid-connected distributed power sources, the difference in current between the three phases may be more significant than that of voltage imbalance.
[0042] In practical engineering, applying mathematical calculation methods to determine the average three-phase load current at the beginning of the distribution line, and then further calculating the corresponding three-phase unbalance, is one of the commonly used methods. The specific formula is as follows:
[0043] The formula for calculating the three-phase current unbalance is as follows:
[0044] The formula represents the maximum value among the three-phase load currents A, B, and C.
[0045] Therefore, the entire system is controlled by a PLC. Its main function is to monitor the voltage and current on both sides of the grid connection point, calculate the grid-side power, load-side power, and inverter system grid-connected power, and finally control the inverter system to connect to the grid.
[0046] The grid-connected power of the inverter system of this invention is controlled by the PLC via RS485 communication. Opto-isolation is used for RS485 communication to isolate and amplify the communication signal, thereby enhancing its anti-interference capability.
[0047] When the PLC determines that the photovoltaic power generation unit needs to be connected to the grid for power supply, it will first issue a command to control the first AC contactor KM0 to close, so that the inverter system is connected to the grid and started up. At the same time, it will send a command to the inverter system through RS485 communication to control the grid-connected output power of the inverter system.
[0048] After the system is running, the voltage and current transmitters convert the analog parameters of the grid voltage, grid-side three-phase current, and load-side three-phase current into digital parameters, which are then transmitted to the PLC. Through data processing, the actual voltage and current values are obtained, and the grid-side three-phase power, load-side three-phase power, and their respective load imbalances at the grid connection point are calculated. These values are stored in the PLC's internal data register and displayed on the touch screen, awaiting the next instruction.
[0049] After the PLC collects and processes the voltage and current signals, the solar energy received by the photovoltaic array is converted into DC power and supplied to the single-phase grid-connected inverter. The grid-connected inverter adjusts internally to obtain the maximum power acquisition and then converts it into AC power that meets the low-voltage grid power standard, or supplies it to the energy storage system for energy storage.
Claims
1. A three-phase imbalance control system for photovoltaic-storage power supply and dynamic power regulation, characterized in that... Current transmitters are installed on the live wires on both the grid side and the load side at the grid connection point, and voltage transmitters are installed on the live wires on the load side. Two current transmitters and one voltage transmitter on each phase of the live wire are connected to an analog-to-digital converter (ADC). The ADC is connected to a PLC, which is connected to the inverter system via an RS485 hub. The inverter system output is connected to the live wire, and the inverter system input is connected to a photovoltaic cell charging controller. The photovoltaic cell charging controller is connected to the battery and the photovoltaic panel. The inverter system includes an A-phase inverter, a B-phase inverter, and a C-phase inverter. The outputs of the A-phase inverter, B-phase inverter, and C-phase inverter are connected to a first AC contactor and then to the grid connection point. The control coil input of the first AC contactor is connected to the PLC. The A-phase live wire is equipped with a first current transmitter and a fourth current transmitter; the B-phase live wire is equipped with a second current transmitter and a fifth current transmitter; and the C-phase live wire is equipped with a third current transmitter and a sixth current transmitter. The first and fourth current transmitters are connected to a first analog-to-digital converter (ADC); the second and fifth current transmitters are connected to a second ADC; the third and sixth current transmitters are connected to a third ADC; the first ADC is connected to a third voltage transmitter; the third voltage transmitter is connected to the A-phase live wire on the load side; the second ADC is connected to the second voltage transmitter; the second voltage transmitter is connected to the B-phase live wire on the load side; and the third ADC is connected to the first voltage transmitter. The voltage transmitter is connected to the C-phase live wire on the load side. The voltage and current transmitters transmit the three-phase voltage at the grid connection point, the three-phase current on the grid side, and the three-phase current on the load side to the PLC via analog-to-digital conversion. This outputs the three-phase power on the grid side, the three-phase power on the load side, and their respective load imbalances at the grid connection point. The PLC determines whether the load-side three-phase power imbalance exceeds a set value. If the load-side three-phase power imbalance is less than the set value, the photovoltaic grid-connected mode is activated for balanced three-phase output power distribution. The PLC sends data to the inverter system to change the inverter output power, and all three inverters simultaneously supply the same power to the grid, which is one-third of the photovoltaic cell capacity. If the load-side three-phase power imbalance exceeds the set value, the PLC then determines whether the grid-side imbalance exceeds a set value. If the value is less than the set value, it indicates that the system has now achieved optimal three-phase power balance. Maintaining the grid connection status and output power of each DC power supply and inverter is sufficient. If the grid-side imbalance exceeds the set value, it indicates that the system is still unbalanced, and the output power needs to be adjusted. When the grid-side imbalance exceeds the set value, the output power is adjusted as follows: First, determine the phase with the highest, middle, and lowest power on the load side. The phase with the highest power on the load side is phase α, the middle phase is phase β, and the phase with the lowest power is phase γ. Then, the inverter that outputs power to the phase with the highest power is the phase α inverter, the inverter that outputs power to the middle phase is the phase β inverter, and the inverter that outputs power to the phase with the lowest power is the phase γ inverter. Calculate δ = the difference between phase α and phase β; ε = the difference between phase α and phase γ. ζ = the difference between the β phase and the γ phase.
2. The three-phase imbalance mitigation system for photovoltaic power supply and dynamic power regulation according to claim 1, characterized in that... The photovoltaic cell charging controller is provided with a second AC contactor between itself and the photovoltaic panel, and the control coil input terminal of the second AC contactor is connected to the PLC.
3. The three-phase imbalance mitigation system for photovoltaic power supply and dynamic power regulation according to claim 1, characterized in that... The photovoltaic cell charging controller is provided with a third AC contactor between itself and the battery, and the control coil input terminal of the third AC contactor is connected to the PLC.
4. The three-phase imbalance mitigation system for photovoltaic power supply and dynamic power regulation according to claim 1, characterized in that... A fourth AC contactor is provided between the photovoltaic cell charging controller and the inverter system, and the control coil input terminal of the fourth AC contactor is connected to the PLC.
5. The three-phase imbalance mitigation system for photovoltaic power supply and dynamic power regulation according to claim 1, 2, 3 or 4, characterized in that... The PLC model mentioned is FX3U48MR.
6. The method for managing the three-phase imbalance of photovoltaic power supply and dynamic power regulation system according to claim 1, characterized in that: If δ≥S, that is, the difference between the maximum phase power and the intermediate phase power on the load side is greater than or equal to the photovoltaic cell capacity, the PLC sends data to the inverter to change the output power of the α phase inverter to the photovoltaic cell capacity, and the inverter power of the β phase inverter and γ phase inverter is 0. If δ < S, that is, the difference between the maximum phase power and the intermediate phase power is less than the photovoltaic cell capacity, determine the magnitude of ε + ζ and S; If ε+ζ≥S, the PLC sends data to the inverter to change the inverter power of the α-phase inverter to δ. Then the remaining available capacity is RES1=S-δ. The PLC sends data to the inverter to distribute the remaining available capacity RES1 equally to the α-phase inverter and the β-phase inverter. That is, the α-phase inverter is δ+RES1 / 2, the β-phase inverter is RES1 / 2, and the γ-phase inverter is 0. If ε+ζ<S, the PLC sends data to the inverter to change the output power of the β-phase inverter to ζ and the inverter power of the α-phase inverter to ε. Then the remaining available capacity is RES1=S-(ε+ζ). The PLC sends data to the inverter to distribute the remaining available capacity RES1 equally among the A-phase inverter, B-phase inverter and C-phase inverter, that is, each phase increases the inverter power by RES1 / 3. That is, the α-phase inverter is ε+RES1 / 3, the β-phase inverter is ζ+RES1 / 3 and the γ-phase inverter is RES1 / 3.
7. The method for managing the three-phase imbalance of the photovoltaic-storage power supply and dynamic power regulation system according to claim 6, characterized in that... After the three inverters simultaneously supply the same power to the grid, they wait for a timer to trigger the next PLC check to determine whether the three-phase power imbalance on the load side is greater than the set value.