Combined energy router and energy regulation and control method thereof

Abstract

The invention provides a combined energy router and an energy regulation and control method thereof, and relates to the technical field of power grid control, and the combined energy router comprises a flexible energy converter, a power electronic converter, a photovoltaic unit and an energy storage unit. The flexible energy converter is connected with the power electronic converter; a combined converter consisting of a flexible energy converter and a power electronic converter is connected with the direct bus; the photovoltaic power supply and the energy storage unit are connected with the combined converter through a direct-current bus; the flexible power converter is connected with an alternating-current power grid, the power electronic converter is connected with an alternating-current load, and the alternating-current power grid is connected with an alternating-current power grid through a power frequency transformer; under the adjusting effect of the flexible power supply converter and the power electronic converter, the alternating current load change is tracked, so that the power supply stability of the alternating current power grid, the photovoltaic unit and the energy storage unit is realized.

Description

Technical Field

[0001] This invention relates to the field of power grid control technology, and in particular to a combined energy router and its energy regulation method. Background Technology

[0002] In recent years, with the continuous advancement of the "dual carbon" target and the urban energy internet, the power system is transforming into a new type of power system dominated by new energy sources, which presents both opportunities and challenges. Due to the hollowing out of urban power grids at the receiving end, large power shortages occur after transmission system failures, necessitating the tapping of local flexibility resources to participate in grid regulation; otherwise, the operation of the receiving-end power grid will be seriously threatened.

[0003] Meanwhile, due to the randomness, nonlinearity, and impulsiveness of new power sources, distribution substations face power quality problems such as voltage fluctuations, harmonic amplification, and three-phase voltage imbalance. The uncertainty of distributed power output may also cause power imbalance in substations, difficulties in operation and control, and insufficient grid-user interaction. Therefore, how to achieve plug-and-play and flexible control of new power sources to improve the operating efficiency and safety level of the power grid is an important issue that urgently needs to be studied.

[0004] In summary, due to the randomness of new energy sources, their connection to the power grid will impact the grid, leading to three-phase voltage imbalance and making power dispatch difficult. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a combined energy router that can solve the technical problems of the prior art, such as the impact on the power grid caused by the randomness of new energy sources, resulting in three-phase voltage imbalance and difficulty in power dispatch.

[0006] A first aspect of this invention provides a combined energy router, comprising:

[0007] Flexible energy converters, power electronic converters, photovoltaic units, and energy storage units;

[0008] The flexible energy converter is connected to the power electronic converter;

[0009] The combined converter, consisting of a flexible energy converter and a power electronic converter, is connected to a direct bus.

[0010] Both the photovoltaic power source and the energy storage unit are connected to the combined converter via a DC bus;

[0011] The flexible power converter is connected to the AC grid, the power electronic converter is connected to the AC load, and the AC grid is connected to the AC grid through the power frequency voltage transformer.

[0012] Under the regulation of flexible power converters and power electronic converters, changes in AC load are tracked to achieve power supply stability for AC grids, photovoltaic units, and energy storage units.

[0013] A second aspect of this invention provides an energy regulation method applied to a combined energy router as described in the first aspect; the method includes:

[0014] S1: Obtain the active power information of the distribution transformer area, which includes the AC power grid and AC load;

[0015] S2: Determine the operating mode of the combined energy router based on the active power information;

[0016] S3: Establish the objective function for the distribution radio station area;

[0017] S4: A hierarchical control strategy for establishing working modes based on the objective function as a constraint;

[0018] S5: Control the combined energy router according to the hierarchical control strategy to achieve energy regulation.

[0019] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0020] In this embodiment of the invention, the combined energy router integrates a flexible energy converter, a power electronic converter, a photovoltaic unit, and an energy storage unit. Through the coordinated operation of these components, it achieves flexible regulation of new energy grid access, solving the grid impact problem caused by the randomness of new energy output. The combined converter, connected to the DC bus, coordinates the conversion of energy from battery storage and photovoltaic power sources with the grid, and regulates the power output through the flexible energy converter and the power electronic converter to stabilize the voltage of the AC grid and AC loads, reducing three-phase voltage imbalance. This structure can effectively balance grid power, optimize the utilization of new energy resources, reduce power system fluctuations, improve grid stability and dispatchability, thereby enhancing the efficiency and security of the entire power system and adapting to the large-scale integration of renewable energy. Attached Figure Description

[0021] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a combined energy router provided in an embodiment of the present invention;

[0023] Figure 2 This is a schematic flowchart of an energy regulation method provided in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the operating mode of a combined energy router provided in an embodiment of the present invention. Attached Figure Description

[0025] L c1 First inductor; L b1 Second inductor; L a1 VT1, third inductor; VT2, first switching transistor; VT3, third switching transistor; VT5, fifth switching transistor; VT6, sixth switching transistor; VT7, seventh switching transistor; T, power frequency transformer; VD1, first insulated-gate bipolar transistor; VD2, second insulated-gate bipolar transistor; VD3, third insulated-gate bipolar transistor; VD4, fourth insulated-gate bipolar transistor; VD5, fifth insulated-gate bipolar transistor; VD6, sixth insulated-gate bipolar transistor; VD7, seventh insulated-gate bipolar transistor; VD8, eighth insulated-gate bipolar transistor; L a2 Fourth inductor; L b2 Fifth inductor; L c2 Sixth inductor; L n2 Seventh inductor; FEC, flexible energy converter; BEC, power electronic converter; C0, voltage stabilizing capacitor. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions 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, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] The combined energy router provided by the present invention will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0028] Reference manual attached Figure 1 The diagram shows a structural schematic of a combined energy router provided in an embodiment of the present invention.

[0029] In the diagram, u GRID This indicates the voltage provided by the power grid in the distribution area, u FEC_abc Indicates the FEC compensation voltage, u SUB_abc This indicates the output voltage on the low-voltage side of the transformer.

[0030] Depend on Figure 1 It can be seen that the power electronic converter adopts a three-phase four-wire structure, which internally includes AC side A, B, and C three-phase bridge arms, a zero-sequence bridge arm, DC side capacitor C0, eight insulated-gate bipolar transistors (IGBTs), anti-parallel diodes, and a filter device. VD1 and VD5 constitute the zero-sequence bridge arm of the power electronic converter. When the three-phase current of the AC side load is unbalanced, the power electronic converter provides zero-sequence compensation to the line through the zero-sequence bridge arm. The output current i of the A, B, and C three-phase bridge arms... a2 i b2 i c2 It is connected in parallel to the three-phase busbar on the low-voltage side of the AC distribution network for harmonic current compensation and reactive power compensation. In addition, the L and C terminals connected to the AC side of the power electronic converter serve as filters, and the C0 terminal connected to the DC side serves as a voltage stabilizer.

[0031] v a1 v b1 v c1 v a2 v b2 v c2 These represent the three-phase phase potentials on the AC side of the FEC and BEC, respectively, v n2 Indicates the zero-sequence potential on the AC side of the BEC, i a1 i b1 i c1 i a2 i b2 i c2 i0 represents the output current of the three-phase bridge arms of FEC and BEC, respectively, and i0 represents the current compensation provided by the zero-sequence bridge arm of BEC for the zero-sequence current.

[0032] In the photovoltaic unit, the output voltage and current of the photovoltaic system port are U, respectively. dc I dc The output port voltage and current of the photovoltaic system are U and U, respectively. PV and I PV The outer loop voltage reference value U is obtained through the MPP control method. ref The photovoltaic converter's PWM is controlled by an outer voltage loop and an inner current loop to ensure that the photovoltaic panel outputs at the maximum power point (MPP) and maximizes the utilization of renewable energy.

[0033] The output port voltage and current of the photovoltaic system are U PV and I PV L connected to the photovoltaic panel PV C PV1 It acts as a filter and is connected to the DC side. PV2 It serves as a voltage stabilizer. Q PVThis indicates that the photovoltaic system uses IGBT power switching devices with anti-parallel freewheeling diodes to achieve DC voltage conversion.

[0034] The energy storage unit is connected to the DC bus via a bidirectional DC / DC converter, and typically employs a dual closed-loop control structure of voltage and current or power and current. The outer loop outputs a reference value to the inner loop via PI regulation, while the inner loop generally uses a current loop to set the charging and discharging current of the energy storage unit. When a power outer loop is used, it acts as a slave control unit, performing peak shaving and valley filling operations; when a voltage outer loop is used, it acts as a master control unit, maintaining a constant DC bus voltage.

[0035] The output port voltage and current of the energy storage unit are U ESS and I ESS Connected to the L of the battery PV It acts as a filter and is connected to the DC side. ESS It serves as a voltage stabilizer. Q ESS1 and Q ESS2 This indicates that the energy storage unit uses an IGBT power switching device with an anti-parallel freewheeling diode to achieve the switching between charging and discharging of the energy storage unit.

[0036] This invention provides a combined energy router, comprising:

[0037] Flexible energy converters, power electronic converters, photovoltaic units, and energy storage units.

[0038] The flexible energy converter is connected to the power electronic converter.

[0039] The combined converter, consisting of a flexible energy converter and a power electronic converter, is connected to a direct bus.

[0040] Both the photovoltaic power source and the energy storage unit are connected to the combined converter via a DC bus.

[0041] The flexible power converter is connected to the AC grid, the power electronic converter is connected to the AC load, and the AC grid is connected to the AC grid through the power frequency voltage transformer.

[0042] Under the regulation of flexible power converters and power electronic converters, changes in AC load are tracked to achieve power supply stability for AC grids, photovoltaic units, and energy storage units.

[0043] Flexible energy converters are primarily used to regulate and control the power exchange between different types of energy sources (such as photovoltaic power sources and energy storage units) and the power grid. They provide flexible energy dispatch to adapt to changes in grid demand and ensure grid stability. Power electronic converters are responsible for converting between AC and DC power, connecting photovoltaic units, energy storage units, the AC grid, and AC loads. They are mainly used to regulate the direction and magnitude of current, thereby achieving precise control of power flow. Photovoltaic units utilize solar energy to convert light energy into electrical energy, typically outputting DC power, which is then connected to the DC bus via a power electronic converter to supply the power system. Energy storage units store electrical energy; they can store energy when photovoltaic power generation is excessive and release energy when sunlight is insufficient or power demand increases, providing power stability. The DC bus provides a power transmission channel for various components in the system, connecting photovoltaic units, energy storage units, and the combined converter to ensure the flow of electrical energy. Power frequency voltage regulators are used to regulate and stabilize the voltage of the AC grid, ensuring power quality and a stable supply.

[0044] This combined energy router precisely regulates power flow through the collaboration of a flexible energy converter and a power electronic converter, enabling power exchange between photovoltaic power sources, energy storage units, and the grid. During this process, the flexible energy converter adapts to grid load changes, ensuring stable power supply to the grid, batteries, and photovoltaic systems. It optimizes the use of renewable energy, reduces the impact of grid instability, and improves grid dispatching capabilities and efficiency. Especially in the case of large-scale renewable energy integration, it effectively reduces voltage fluctuations and power imbalances, enhancing grid operational stability and security.

[0045] In this embodiment of the invention, the combined energy router integrates a flexible energy converter, a power electronic converter, a photovoltaic unit, and an energy storage unit. Through the coordinated operation of these components, it achieves flexible regulation of new energy grid access, solving the grid impact problem caused by the randomness of new energy output. The combined converter, connected to the DC bus, coordinates the conversion of energy from battery storage and photovoltaic power sources with the grid, and regulates the power output through the flexible energy converter and the power electronic converter to stabilize the voltage of the AC grid and AC loads, reducing three-phase voltage imbalance. This structure can effectively balance grid power, optimize the utilization of new energy resources, reduce power system fluctuations, improve grid stability and dispatchability, thereby enhancing the efficiency and security of the entire power system and adapting to the large-scale integration of renewable energy.

[0046] In one possible implementation, the flexible energy converter includes a first switch, a second switch, a third switch, a fifth switch, a sixth switch, and a seventh switch.

[0047] The first switch and the fifth switch form the first series branch.

[0048] The second switch and the sixth switch form a second series branch.

[0049] The third switch and the seventh switch form the third series branch.

[0050] The first series branch, the second series branch, and the third series branch are connected in parallel.

[0051] The flexible energy converter also includes a first inductor, a second inductor, and a third inductor.

[0052] The first inductor is connected between the first and fifth switching transistors. The second inductor is connected between the second and sixth switching transistors. The third inductor is connected between the third and seventh switching transistors.

[0053] The first, second, and third inductors form an inductive connection with the three-phase branch of the AC power grid.

[0054] Specifically, this flexible energy converter utilizes multiple switching transistors and inductors to regulate and control electrical energy. Specifically, three switching transistors are connected in series to form three branches, which are then connected in parallel to form the main circuit, thereby distributing and regulating the current. Each branch is equipped with an inductor to smooth current changes, reduce current fluctuations, and improve system stability. The inductors are inductively connected to the three-phase branches of the AC grid, which helps balance the load and improve the power factor, ensuring stable grid operation. The advantages of this structure lie in its ability to flexibly respond to grid load changes, optimize energy utilization, improve power quality and system reliability through precise switching transistor control and inductor regulation, making it particularly suitable for systems with large-scale renewable energy integration.

[0055] In one possible implementation, the power frequency voltage transformer and the AC load are connected in a four-wire configuration.

[0056] The power electronic converter includes a first insulated-gate bipolar transistor, a second insulated-gate bipolar transistor, a third insulated-gate bipolar transistor, a fourth insulated-gate bipolar transistor, a fifth insulated-gate bipolar transistor, a sixth insulated-gate bipolar transistor, a seventh insulated-gate bipolar transistor, and an eighth insulated-gate bipolar transistor.

[0057] The first insulated-gate bipolar transistor and the fifth insulated-gate bipolar transistor form the fourth series branch.

[0058] The second insulated-gate bipolar transistor and the sixth insulated-gate bipolar transistor form the fifth series branch.

[0059] The third insulated-gate bipolar transistor and the seventh insulated-gate bipolar transistor form the sixth series branch.

[0060] The fourth insulated-gate bipolar transistor and the eighth insulated-gate bipolar transistor form the seventh series branch.

[0061] The fourth series branch, the fifth series branch, the sixth series branch, and the seventh series branch are connected in parallel.

[0062] The power electronic converter also includes a fourth inductor, a fifth inductor, a sixth inductor, and a seventh inductor, which are respectively connected to each phase line in the four-wire connection.

[0063] The fourth inductor is connected between the fourth insulated-gate bipolar transistor and the eighth insulated-gate bipolar transistor.

[0064] The fifth inductor is connected between the third insulated-gate bipolar transistor and the seventh insulated-gate bipolar transistor.

[0065] The sixth inductor is connected between the second insulated-gate bipolar transistor and the sixth insulated-gate bipolar transistor.

[0066] The seventh inductor is connected between the first insulated-gate bipolar transistor and the fifth insulated-gate bipolar transistor.

[0067] The power electronic converter also includes stabilizing capacitors connected in parallel with the third series branch and the fourth series branch, respectively.

[0068] The two ends of the third series branch are connected to the DC bus respectively.

[0069] Specifically, this power electronic converter structure utilizes multiple insulated-gate bipolar transistors (IGBTs) and inductors to achieve precise current control and power regulation. Each pair of IGBTs connected in series forms a branch, and the four branches are connected in parallel to handle the power exchange between the AC load and the DC bus. An inductor is incorporated into each series branch to smooth current fluctuations, reduce high-frequency noise, and suppress voltage fluctuations. Voltage stability is further ensured through the inclusion of a voltage-stabilizing capacitor. The power electronic converter uses a four-wire connection to the AC grid, effectively balancing the three-phase current and load to ensure efficient system operation and power quality. The advantages of this structure are: through precise IGBT control and inductor regulation, it can not only cope with complex load changes but also optimize power flow and improve system reliability, making it particularly suitable for power systems with high power and high precision requirements.

[0070] In one possible implementation, the photovoltaic unit includes a photovoltaic panel and a unidirectional DC / DC converter.

[0071] The photovoltaic panel is connected to the DC bus via a unidirectional DC / DC converter.

[0072] A unidirectional DC / DC converter is a power electronic device specifically designed to convert DC voltage to different voltage levels, allowing current to flow in only one direction. In photovoltaic (PV) systems, the unidirectional DC / DC converter adjusts the DC voltage generated by the PV panels to a voltage level suitable for the grid or energy storage unit. The main function of this converter is to optimize the output voltage of the PV panels, enabling it to effectively coordinate and regulate with other system components, such as the DC bus. The PV units are connected to the unidirectional DC / DC converter via the PV panels, which efficiently adjusts the output voltage of the PV panels to the voltage required by the system and transmits it to the DC bus. The advantages of this structure are: through the precise control of the unidirectional DC / DC converter, the power output of the PV panels can be maximized, and a stable voltage supply can be provided, ensuring the efficient and stable operation of the system.

[0073] In one possible implementation, the energy storage unit includes an energy storage battery and a bidirectional DC / DC converter.

[0074] The energy storage battery is connected to the DC bus via a bidirectional DC / DC converter.

[0075] A bidirectional DC / DC converter is a power electronic device capable of converting electrical energy in two directions: it can convert DC voltage from one level to another and also allow current to flow in reverse. This type of converter is commonly used in energy storage systems, where it can control the charging and discharging process of batteries as needed. Specifically, the bidirectional DC / DC converter can convert the electrical energy in the energy storage battery into a voltage suitable for the system's needs, and store electrical energy from the grid or other power sources into the battery while it is charging. The energy storage unit is connected to the bidirectional DC / DC converter via the energy storage battery, effectively regulating the battery's charging and discharging process. This allows the battery to store energy when there is excess power and release energy during peak demand periods. Through the flexible control of the bidirectional DC / DC converter, this structure can ensure stable battery voltage and current during energy storage, thereby improving energy utilization efficiency and ensuring a long battery life. Simultaneously, it can also balance grid load, enhancing system stability and reliability.

[0076] Reference manual attached Figure 2 The diagram shows a flowchart of an energy regulation method provided by an embodiment of the present invention.

[0077] S1: Obtain the active power information of the distribution transformer area, which includes the AC power grid and AC load.

[0078] In this context, a distribution substation refers to the area within a power system responsible for power distribution, encompassing the AC grid and the AC loads connected to it. Active power refers to the portion of electrical energy actually used in the power system. Obtaining active power information from distribution substations is crucial for understanding the power demand of the grid and loads, enabling subsequent energy dispatching. Based on this information, the system can precisely adjust the power supply methods of photovoltaic systems, energy storage, or the grid to ensure stable grid operation.

[0079] S2: Determine the operating mode of the combined energy router based on the active power information.

[0080] In one possible implementation, the operating modes include a photovoltaic-storage power supply mode and a grid-supported mode.

[0081] S2 specifically refers to:

[0082] When active power information is missing, the operating mode is switched to grid support mode; otherwise, the operating mode is switched to photovoltaic-storage power supply mode.

[0083] The photovoltaic-storage power supply mode refers to the system prioritizing the use of photovoltaic power and energy storage units to supply power to the load when there is sufficient photovoltaic power generation and energy storage unit capacity. In this mode, the system dynamically adjusts the energy supply based on changes in actual photovoltaic and energy storage capacity. For example, when photovoltaic power generation capacity is sufficient, the system prioritizes the use of photovoltaic power. When photovoltaic power generation is insufficient, energy storage units provide supplementary power. The grid support mode involves the system relying on the grid for power supply when photovoltaic power generation or energy storage unit capacity is insufficient, or when there is a lack of active power, the system obtains additional power support from the grid to ensure a stable power supply to the load. This typically occurs when there is a power gap in the grid, requiring the energy storage system or photovoltaic system to supplement the load demand, with the grid making up the shortfall.

[0084] Based on active power information, the system can dynamically switch between photovoltaic (PV) power generation and energy storage mode or grid support mode. When PV power generation and energy storage capacity are sufficient, the PV power storage mode is selected to reduce dependence on the grid. When active power information is missing or battery capacity is insufficient, the system automatically switches to grid support mode to ensure a continuous and stable power supply.

[0085] S3: Establish the objective function for the distribution radio station area.

[0086] In one possible implementation, the objective function is specifically formulated as follows:

[0087] .

[0088] in, This indicates taking the minimum value. This indicates the weight for maximizing photovoltaic utilization. Indicates the cost weighting of peak and off-peak electricity prices. This represents the amount of photovoltaic power curtailed at time t. This represents the maximum possible output power of the photovoltaic system at time t. This represents the electricity price at time t. Indicates the duration of electricity price accumulation. This represents the power output of the power grid at time t.

[0089] Specifically, the objective function is constructed with the goals of maximizing the absorption of new energy sources and minimizing electricity prices. This objective function is used to optimize energy use and dispatch within the system. It aims to optimize system operating efficiency, maximize the absorption of renewable energy sources (such as photovoltaics), and reduce the cost of electricity purchased by the grid. By minimizing the combination of photovoltaic curtailment and grid-used power, and considering electricity price fluctuations, the system can maximize the utilization of photovoltaic power while ensuring power supply and reducing electricity costs during peak-price periods.

[0090] S4: Establish a hierarchical control strategy for working modes based on the objective function as a constraint.

[0091] Among them, the hierarchical control strategy is a multi-level control method. In this strategy, the system decomposes complex control tasks into multiple levels for processing, thereby achieving flexible optimization and adjustment at different levels. By decomposing the overall optimization objective into multiple levels of tasks, the hierarchical control strategy can flexibly respond to demand adjustments under different operating modes. At each level, the control strategy adjusts according to the objective function, ensuring that the system can achieve a balance between maximizing renewable energy utilization and reducing grid dependence, thereby improving energy efficiency.

[0092] In one possible implementation, when the operating mode is photovoltaic energy storage power supply mode, S4 specifically includes:

[0093] S401: Obtain the photovoltaic power source, energy storage unit, and total power.

[0094] S402: When the total power supply meets the AC load, the system is determined to be in combined power supply mode. When the photovoltaic power supply meets the AC load and the energy storage unit has zero power, the system is determined to be in photovoltaic power supply mode. When the energy storage unit has the AC load and the photovoltaic unit has zero power, the system is determined to be in energy storage power supply mode.

[0095] S403: Obtain the photovoltaic unit control mode, which includes MPPT control mode, power limiting control mode and standby control mode.

[0096] S404: When both the combined power supply mode and MPPT control mode are satisfied, AC loads are supplied through photovoltaic units and energy storage units.

[0097] When both the combined power supply mode and the power limiting control mode are met, the energy storage unit is switched to standby mode, and the photovoltaic unit supplies power to the AC load.

[0098] When both photovoltaic power supply mode and MPPT control mode are satisfied, the energy storage unit is switched to standby mode, and the photovoltaic unit supplies power to the AC load.

[0099] While simultaneously satisfying both photovoltaic power supply mode and power limiting control mode, the photovoltaic unit supplies power to the AC load and energy storage unit.

[0100] When the energy storage power supply mode is met, the photovoltaic unit is switched to standby mode, and the AC load is powered through the energy storage unit.

[0101] Among them, MPPT (Maximum Power Point Tracking) control mode is a technology used to optimize the output power of photovoltaic systems. The output power of photovoltaic panels varies with changes in light intensity and temperature. MPPT technology monitors and adjusts the operating state of photovoltaic cells in real time, ensuring that they always operate at their maximum power point (MPP). At the maximum power point, the photovoltaic panel can output its maximum possible power.

[0102] It should be noted that this process dynamically adjusts the power supply mode based on the power levels of the photovoltaic (PV) power source and energy storage unit, ensuring efficient energy utilization. When both PV and energy storage have sufficient power, a combined power supply mode is used, with both PV and energy storage providing power. When either power source is insufficient, the system automatically switches to either PV power supply mode or energy storage power supply mode. Simultaneously, the control modes of the PV units (such as MPPT control mode and power limiting control mode) further optimize energy output, ensuring stable system operation. The advantage of this process is its ability to flexibly adjust the power supply mode according to power demand and electricity price fluctuations, maximizing the utilization of renewable energy, reducing dependence on the grid, and improving the system's economy and reliability.

[0103] Specifically, the large-scale grid connection of renewable energy and the reduction in energy storage costs have made it possible to supply energy solely through photovoltaic (PV) and energy storage. Based on the different regulation of the PV and energy storage units, the PV-energy storage supply mode can be divided into three modes: First: In this mode, the PV and energy storage units are sufficient to supply power to the load. If the PV operates under MPP control, the energy storage unit supplies power to the load along with the PV unit. If the PV unit operates under power limiting control, the energy storage unit is in standby mode. Second: In this mode, the PV unit supplies power to the load. If the PV operates under MPP control, the energy storage unit is in standby mode. If the PV unit operates under power limiting control, the PV unit can not only supply power to the load but also charge the energy storage unit to its SOCmax state. Third: In this mode, the energy storage unit supplies power to the load, and the PV unit is out of operation.

[0104] In one possible implementation, when the operating mode is grid support mode, S4 specifically includes:

[0105] S405: When the state of charge of the energy storage unit is between the maximum state of charge and the minimum state of charge: If the electricity price is greater than a first electricity price, the energy storage unit is switched to a discharging state. If the electricity price is less than a second electricity price, the energy storage unit is switched to a standby state. If the electricity price is between the first and second electricity prices, the energy storage unit is switched to a charging state, wherein the first electricity price is greater than the second electricity price.

[0106] It should be noted that this process achieves flexible power regulation by combining electricity price fluctuations with the state of charge of the energy storage unit. When electricity prices are high, the energy storage unit discharges to support grid power supply. When electricity prices are low, the energy storage unit stands by to avoid unnecessary energy consumption. When electricity prices are moderate, the energy storage unit charges, utilizing the low-priced electricity for storage. The advantage of this process is that it maximizes the economic benefits brought about by electricity price differences, reduces energy costs during peak grid load periods, and simultaneously improves the system's economics and energy utilization efficiency.

[0107] The first electricity price and the second electricity price can be set according to actual needs. Optionally, the first electricity price can be set as the peak electricity price and the second electricity price can be set as the off-peak electricity price.

[0108] Specifically, when the output of photovoltaic (PV) units drops sharply or the energy storage unit is constrained by its State of Charge (SOC), the system experiences an active power deficit, requiring power support from the grid and entering grid support mode. When the energy storage unit's state of charge (SOC) is between its maximum and minimum SOC, further subdivisions are made based on time-of-use pricing. During peak electricity demand, the energy storage unit discharges and supplies power to the grid. During off-peak demand, the energy storage unit is charged by the grid; in this state, the energy storage unit's output power is less than zero, indicating it is in a charging state. When electricity is at parity, the energy storage unit's output power is zero, and it is in standby mode, with the grid and PV units supplying power to the load.

[0109] S5: Control the combined energy router according to the hierarchical control strategy to achieve energy regulation.

[0110] Specifically, the primary goal of the system operation is to maintain the stability of the voltage frequency in the power grid and maintain stability through the switching of the control methods of each unit. When the system operates normally, with economy and reliability as the goals, the power distribution within the system in different modes is analyzed. The system adopts master-slave control, selects a power electronic converter as the master controller, and adopts a constant voltage and constant frequency control method to support the voltage of the DC microgrid, maintain the stability of the DC voltage, and achieve bidirectional energy flow. The energy storage unit acts as a slave controller. Under the constant power control mode, the energy storage unit transmits power according to the system requirements.

[0111] In the operation control strategy of the photovoltaic power generation system, the photovoltaic unit usually always follows the maximum power point (MPPT) control mode to optimize the output power of the photovoltaic array. Only when the system encounters a special working condition of power supply-demand imbalance, the photovoltaic unit will dynamically switch to the power-limited operation mode to ensure the overall power balance and stable operation of the system.

[0112] In the actual application process, this process flexibly adjusts the energy supply by dynamically adjusting the energy supply modes of the photovoltaic and energy storage and the grid support mode, according to the power demand and the energy storage power. When the photovoltaic and energy storage power is sufficient, the photovoltaic and energy storage units are preferentially used for power supply to reduce the dependence on the power grid. When the power demand exceeds the photovoltaic and energy storage power, it automatically switches to the grid support mode to obtain additional power support from the grid. The system maximizes the photovoltaic power generation efficiency through the MPPT control mode and adjusts the charge and discharge state of the energy storage unit according to the electricity price fluctuation to achieve low-cost energy scheduling. The advantages of this process are to improve the consumption capacity of renewable energy, maximize the power utilization efficiency, reduce the energy cost, reduce the power expenditure during peak electricity price periods, and enhance the economy and reliability of the system.

[0113] Refer to the appendix of the specification Figure 3 , which shows a schematic diagram of the operation mode of a combined energy router provided by an embodiment of the present invention.

[0114] Figure 3 In Figure 3 (a) is a graph of the real-time electricity price change of the system, reflecting the change of the grid electricity price over time; Figure 3 (b) P LOAD represents the power required by the load in the distribution area, reflecting the load fluctuations of distribution areas 1 and 2; Figure 3 (c) P GRID represents the output power of the distribution area power grid, reflecting the change of the output power of the distribution area power grids of distribution areas 1 and 2; Figure 3 (d) U DC is the voltage waveform diagram of the DC side; Figure 3(e) shows the power transmission diagram of the two-station interconnection line, P DC This reflects the power interaction between the two stations, with the flow from station 1 to station 2 as the positive direction; Figure 3 (f)P PV P is the output power of the photovoltaic unit. ESS The power change of the energy storage unit is represented by discharge as the positive direction.

[0115] For example, such as Figure 2 As shown, under the photovoltaic-storage power supply mode, 00:00-04:00 and 10:00-13:00 are designated as off-peak periods based on electricity prices, 17:00-21:00 are designated as peak periods, and the remaining periods are designated as flat-price periods.

[0116] Between 04:00 and 05:00, the load on both areas increases to 1 kW. At this time, it is in operation mode 1-3, the photovoltaic unit is still in standby mode, and the energy storage unit generates power.

[0117] Between 06:00 and 08:00, the load on both areas increases to 2 kW, which is the normal operating mode, and the photovoltaic unit output power is 4 kW.

[0118] Between 09:00 and 10:00, the load on both photovoltaic (PV) units drops to 1 kW, operating under Mode 1-2. The PV units operate under MPPT control with an output power of 5 kW, while the energy storage units are in standby mode. Between 11:00 and 13:00, the load on both units is 1.5 kW, also operating under Mode 1-2. The energy storage units are charging, charging to their maximum capacity. The PV units operate under power limiting control, and curtailment occurs once the load and energy storage unit requirements are met.

[0119] During the period from 13:00 to 14:00, the load of both areas is 2.5 kW, which is in mode 1-2. The photovoltaic unit operates under MPPT control and outputs 5 kW.

[0120] At 15:00, the load of transformer area 1 is 1.5 kW and the load of transformer area 2 is 1.5 kW. At this time, it is in mode 1-2, and the photovoltaic unit is operating under MPPT control with an output power of 3 kW.

[0121] At 16:00, the load of transformer area 1 is 2 kW and the load of transformer area 2 is 4 kW. At this time, it is in mode 1-2. The photovoltaic unit is operating under MPPT control and the output power is 2 kW. The power deficit is supplemented by the grid.

[0122] Secondly, in the grid support mode, such as Figure 2As shown, during the period from 00:00 to 03:00, the load of both substations is 0.5kW. At this time, it is in grid support mode, the photovoltaic unit is in standby mode, and the energy storage unit is charged to the maximum energy storage limit when the electricity price is low. The load of both substations is supplied by the substation grid.

[0123] During the period from 17:00 to 19:00, the load of area 1 is 2 kW and the load of area 2 is 5 kW. At this time, it is in grid support mode. The photovoltaic unit is in standby mode, the energy storage unit outputs 3 kWh of electricity, and the remaining power deficit is provided by the grid. Since the load of area 2 exceeds the transformer overload constraint, the grid of area 1 transmits power to the load of area 2.

[0124] The period from 20:00 to 24:00 is the grid support mode, during which both photovoltaic units and energy storage units are in standby mode. The grid provides energy to the distribution area as the load changes.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A combined energy router, characterized in that, include: Flexible energy converters, power electronic converters, photovoltaic units, and energy storage units; The flexible energy converter is connected to the power electronic converter; The combined converter, consisting of the flexible energy converter and the power electronic converter, is connected to a direct bus. Both the photovoltaic power source and the energy storage unit are connected to the combined converter via the DC bus; The flexible power converter is connected to the AC power grid, the power electronic converter is connected to the AC load, and the AC power grid is connected to the AC power grid through a power frequency voltage transformer; Under the regulation of the flexible power converter and the power electronic converter, the AC load changes are tracked to achieve power supply stability for the AC grid, the photovoltaic unit, and the energy storage unit.

2. The combined energy router according to claim 1, characterized in that, The flexible energy converter includes a first switch, a second switch, a third switch, a fifth switch, a sixth switch, and a seventh switch. The first switch and the fifth switch form a first series branch; The second switch and the sixth switch form a second series branch; The third switch and the seventh switch form a third series branch; The first series branch, the second series branch, and the third series branch are connected in parallel; The flexible energy converter also includes a first inductor, a second inductor, and a third inductor; The first inductor is connected between the first switch and the fifth switch; the second inductor is connected between the second switch and the sixth switch; and the third inductor is connected between the third switch and the seventh switch. The first inductor, the second inductor, and the third inductor form an inductive connection with the three-phase branch of the AC power grid.

3. The combined energy router according to claim 1, characterized in that, The power frequency voltage transformer and the AC load are connected in a four-wire configuration. The power electronic converter includes a first insulated-gate bipolar transistor, a second insulated-gate bipolar transistor, a third insulated-gate bipolar transistor, a fourth insulated-gate bipolar transistor, a fifth insulated-gate bipolar transistor, a sixth insulated-gate bipolar transistor, a seventh insulated-gate bipolar transistor, and an eighth insulated-gate bipolar transistor. The first insulated-gate bipolar transistor and the fifth insulated-gate bipolar transistor form a fourth series branch; The second insulated-gate bipolar transistor and the sixth insulated-gate bipolar transistor form a fifth series branch; The third insulated-gate bipolar transistor and the seventh insulated-gate bipolar transistor form a sixth series branch; The fourth insulated-gate bipolar transistor and the eighth insulated-gate bipolar transistor form a seventh series branch; The fourth series branch, the fifth series branch, the sixth series branch, and the seventh series branch are connected in parallel; The power electronic converter also includes a fourth inductor, a fifth inductor, a sixth inductor, and a seventh inductor, which are respectively connected to each phase line in the four-wire connection method; The fourth inductor is connected between the fourth insulated-gate bipolar transistor and the eighth insulated-gate bipolar transistor; The fifth inductor is connected between the third insulated-gate bipolar transistor and the seventh insulated-gate bipolar transistor; The sixth inductor is connected between the second insulated gate bipolar transistor and the sixth insulated gate bipolar transistor; The seventh inductor is connected between the first insulated-gate bipolar transistor and the fifth insulated-gate bipolar transistor; The power electronic converter also includes voltage stabilizing capacitors connected in parallel with the third series branch and the fourth series branch, respectively; The two ends of the third series branch are respectively connected to the DC bus.

4. The combined energy router according to claim 1, characterized in that, The photovoltaic unit includes a photovoltaic panel and a unidirectional DC / DC converter; The photovoltaic panel is connected to the DC bus via the unidirectional DC / DC converter.

5. The combined energy router according to claim 1, characterized in that, The energy storage unit includes an energy storage battery and a bidirectional DC / DC converter; The energy storage battery is connected to the DC bus via the bidirectional DC / DC converter.

6. An energy regulation method, characterized in that, Applied to the combined energy router according to any one of claims 1 to 5; the method includes: S1: Obtain the active power information of the distribution substation, wherein the distribution substation includes the AC power grid and the AC load; S2: Determine the operating mode of the combined energy router based on the active power information; S3: Establish the objective function for the aforementioned distribution radio area; S4: Establish a hierarchical control strategy for the working mode based on the objective function; S5: Control the combined energy router according to the hierarchical control strategy to achieve energy regulation.

7. The energy regulation method according to claim 6, characterized in that, The operating modes include photovoltaic-storage power supply mode and grid support mode; Specifically, S2 is: When the active power information is missing, the operating mode is switched to the grid support mode; otherwise, the operating mode is switched to the photovoltaic-storage power supply mode.

8. The energy regulation method according to claim 6, characterized in that, The objective function is specifically formulated as follows: ； in, This indicates taking the minimum value. This indicates the weight for maximizing photovoltaic utilization. Indicates the cost weighting of peak and off-peak electricity prices. This represents the amount of photovoltaic power curtailed at time t. This represents the maximum possible output power of the photovoltaic system at time t. This represents the electricity price at time t. Indicates the duration of electricity price accumulation. This represents the power output of the power grid at time t.

9. The energy regulation method according to claim 7, characterized in that, When the operating mode is the photovoltaic energy storage power supply mode, S4 specifically includes: S401: Obtain the photovoltaic power source, the energy storage unit, and the total power; S402: When the total power supply meets the AC load, the system is determined to be in a combined power supply mode; when the power supply of the photovoltaic power source meets the AC load and the power of the energy storage unit is zero, the system is determined to be in a photovoltaic power supply mode; when the power of the energy storage unit meets the AC load and the power of the photovoltaic unit is zero, the system is determined to be in an energy storage power supply mode. S403: Obtain the photovoltaic unit control mode, wherein the photovoltaic unit control mode includes MPPT control mode, power limiting control mode and standby control mode; S404: When both the combined power supply mode and the MPPT control mode are satisfied, the AC load is powered through the photovoltaic unit and the energy storage unit; When both the combined power supply mode and the power limiting control mode are satisfied, the energy storage unit is switched to standby mode, and the photovoltaic unit supplies power to the AC load. When both the photovoltaic power supply mode and the MPPT control mode are satisfied, the energy storage unit is switched to standby mode, and the photovoltaic unit supplies power to the AC load. When both the photovoltaic power supply mode and the power limiting control mode are satisfied, the photovoltaic unit supplies power to the AC load and the energy storage unit. When the energy storage power supply mode is met, the photovoltaic unit is switched to standby mode, and the energy storage unit supplies power to the AC load.

10. The energy regulation method according to claim 9, characterized in that, When the operating mode is the power grid support mode, S4 specifically includes: S405: When the state of charge of the energy storage unit is between the maximum state of charge and the minimum state of charge; if the electricity price is greater than the first electricity price, the energy storage unit is switched to the discharge state; if the electricity price is less than the second electricity price, the energy storage unit is switched to the standby state; if the electricity price is between the first electricity price and the second electricity price, the energy storage unit is switched to the charging state, wherein the first electricity price is greater than the second electricity price.

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