Water-light-storage integrated micro-grid system and control method thereof

Abstract

The invention relates to a water-light-storage integrated micro-grid system and a control method thereof. The system comprises a distributed hydroelectric power supply, a distributed photovoltaic power supply, an energy storage system, a medium-voltage AC-DC flexible interconnection device, a micro-grid energy management system and a load. The medium-voltage AC / DC flexible interconnection device is connected in series between a grid-connected point of the micro-grid and a superior power distribution network, an AC port of the medium-voltage AC / DC flexible interconnection device is used for realizing flexible power flow mutual aid between the micro-grid and the superior power distribution network, and a DC port of the medium-voltage AC / DC flexible interconnection device is used for being connected with an energy storage system; and the micro-grid energy management system is in communication connection with the distributed hydroelectric power supply, the distributed photovoltaic power supply, the energy storage system and the medium-voltage AC / DC flexible interconnection device, and is used for collecting system operation data, executing an optimization control strategy and realizing autonomous operation of the micro-grid and cooperative control of the micro-grid and a superior power distribution network. The system can effectively cope with seasonal load peaks, greatly improve the local consumption rate of distributed water and light resources, and enhance the power supply reliability and operation flexibility of a local power grid.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power systems, and particularly relates to a water-light-storage integrated micro-grid system and a control method thereof. BACKGROUND

[0002] At present, the penetration rate of distributed renewable energy represented by wind power and photovoltaic power in distribution networks is increasing. However, the output of such power sources is intermittent and volatile, and the large-scale grid connection of such power sources brings challenges to the stable operation of traditional power grids. Micro-grid, as a local energy system capable of integrating distributed power sources, energy storage, and loads and coordinating control, is an effective means to improve renewable energy consumption and enhance power supply reliability.

[0003] In some specific areas, such as famous tea-producing areas, the load shows strong seasonal characteristics. For example, during the tea-making season, the electricity load will surge to several times the level of ordinary days in a short time, bringing great pressure to the local power grid. At the same time, such areas often contain rich distributed resources such as small hydropower and rooftop photovoltaic power. The existing micro-grid technical solutions mostly focus on solving the problem of renewable energy volatility or providing basic island operation capability, and lack a deep integration solution for the special scenario of "strong seasonal load + high proportion of distributed clean energy". Conventional power grid reinforcement methods (such as new lines and increased capacity of main transformers) often face problems such as huge investment and difficult path coordination (such as crossing ecological protection areas) in these areas.

[0004] In addition, the connection of traditional micro-grid and main grid usually adopts rigid grid connection mode, and the power regulation capability is limited, which is difficult to realize flexible interconnection and precise control of power flow with the distribution network. The configuration of the energy storage system is mostly based on experience or simple shortage calculation, and cannot be deeply coupled with the time sequence characteristics of the source and load, resulting in low utilization or poor effect. Therefore, an innovative micro-grid technical solution is urgently needed to systematically solve the local power supply reliability, improve the local consumption of clean energy, and adapt to extreme load fluctuations. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a water-light-storage integrated micro-grid system and a control method thereof. The system, through innovative architecture design and coordinated control strategy, can effectively cope with seasonal load peaks, greatly improve the local consumption rate of distributed water and light resources, and enhance the power supply reliability and operational flexibility of the local power grid.

[0006] To achieve the above purpose, the present application adopts the following technical solution: a water-light-storage integrated micro-grid system, comprising: a distributed hydropower source, a distributed photovoltaic power source, an energy storage system, a medium-voltage AC / DC flexible interconnection device, a micro-grid energy management system, and a load. The medium-voltage AC / DC flexible interconnection device is connected in series between a grid connection point of the micro-grid and a superior distribution network, an AC port of the medium-voltage AC / DC flexible interconnection device is used to realize flexible power flow interconnection between the micro-grid and the superior distribution network, and a DC port of the medium-voltage AC / DC flexible interconnection device is used to connect the energy storage system. The micro-grid energy management system is in communication connection with the distributed hydroelectric power source, the distributed photovoltaic power source, the energy storage system and the medium-voltage AC / DC flexible interconnection device, is used to collect system operation data, and execute an optimal control strategy, so as to realize autonomous operation of the micro-grid and collaborative control of the micro-grid and the superior distribution network.

[0007] Further, the medium-voltage AC / DC flexible interconnection device comprises a shunt transformer, a series transformer, a shunt-side inverter, a series-side inverter and a bypass module. The primary side of the shunt transformer is connected in parallel to a line, and the secondary side of the shunt transformer is connected to the shunt-side inverter, so as to provide an AC power source and support a DC bus voltage. The primary side of the series transformer is connected in series to a line, and the secondary side of the series transformer is connected to the series-side inverter, so as to realize directional flow and stepless adjustment of power flow by adjusting the amplitude and phase of the voltage of the secondary side. The bypass module is composed of anti-parallel thyristors and contactors, when a short-circuit fault occurs in the line, the thyristors are first turned on, and then the contactors are closed, so as to connect the series reactance into the fault circuit to realize current limiting protection, and the permanent magnet type vacuum circuit breaker in the device is tripped and split within 10-20 ms.

[0008] Further, the rated voltage of the DC port of the medium-voltage AC / DC flexible interconnection device is 1500V, and the energy storage system is directly connected to the DC port through a DC converter at 1500V DC, so as to realize plug and play.

[0009] Further, the configuration capacity of the energy storage system is determined based on multi-working condition power balance analysis of a typical daily load curve of the micro-grid and a distributed power output curve, and the configuration target is to smooth the daily load peak-valley difference and improve the local consumption rate of distributed energy; the energy storage system adopts a containerized integrated design, and is internally provided with a cluster of lithium iron phosphate batteries, a battery management system, a DC converter and a fire control and temperature control system.

[0010] Further, the micro-grid energy management system adopts a hierarchical control architecture, and comprises: The local control layer is composed of local controllers deployed in the energy storage system and the flexible interconnection device, and is responsible for data collection and fast closed-loop control of the bottom layer equipment; The centralized control layer is deployed with the micro-grid energy management system, and is used to realize integration of all network data, operation state monitoring, optimal scheduling algorithm calculation and issuing of control instructions to the local control layer; The scheduling layer is a superior power distribution master station system, used to issue macroscopic scheduling instructions to the micro-grid energy management system, so as to realize global collaborative optimization of the power distribution network and the micro-grid.

[0011] The application also provides a control method of the water-light-storage integrated micro-grid system. S1: The micro-grid energy management system collects real-time load power, distributed water and photovoltaic output, energy storage system state, grid-connected point exchange power and scheduling instructions of the superior power distribution network in the micro-grid. S2: According to the operation data, the current operation condition of the system is judged, and the condition at least includes the spring tea-making peak period, the spring non-tea-making period and the typical day in the non-abundant water period. S3: Based on the current condition, the corresponding optimization control strategy is executed, and the strategy includes the energy storage system charging and discharging strategy, the power mutual aid strategy of the medium-voltage AC-DC flexible interconnection device and the photovoltaic output control strategy.

[0012] Further, when it is judged that the current condition is the spring tea-making peak period, the energy storage system charging and discharging strategy is: charging in the period from early morning to noon when the load is relatively low or the photovoltaic output is large, and discharging in the afternoon to the evening tea-making load peak period, so as to reduce the load peak value; the medium-voltage AC-DC flexible interconnection device controls the rate and size of the power absorbed from the superior power distribution network according to the power shortage in the micro-grid.

[0013] Further, when it is judged that the current condition is the typical day in the non-abundant water period, the energy storage system charging and discharging strategy is: executing the mode of 'one charging and one discharging' in a day, charging in the noon photovoltaic large period or the night load low period, and discharging in the evening load peak period, so as to smooth the daily net load fluctuation; the medium-voltage AC-DC flexible interconnection device is mainly used to maintain the stability of the power exchange at the grid-connected point.

[0014] Further, it further includes a heavy overload collaborative control step: When it is monitored that the heavy overload occurs in the micro-grid or the associated power distribution network line, the energy storage system is preferentially dispatched to discharge to provide support power; If the energy storage system is insufficient, the medium-voltage AC-DC flexible interconnection device is used to flexibly mutual aid power from the superior power distribution network or the adjacent non-heavy overload line; If the distributed photovoltaic output aggravates the heavy overload, the photovoltaic power is controlled.

[0015] Further, the micro-grid energy management system communicates with the superior power distribution master station system through a 5G power virtual private network, receives scheduling instructions and uploads the adjustable capacity, operation state and abnormal information of the micro-grid; at the same time, the wireless network or optical fiber is used to communicate with the dispersed distributed photovoltaic inverter, collect data and issue start-stop and power control instructions.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a comprehensive solution for the complex scenario of "seasonal impact load + high proportion of distributed clean energy", from system architecture and equipment configuration to control strategy, effectively solving the problems of power supply reliability and green energy use in areas where conventional power grid transformation is difficult.

[0017] 2. By introducing a medium-voltage AC / DC flexible interconnection device, this invention achieves millisecond-level, stepless flexible regulation of power flow between the microgrid and the main grid. This not only improves the flexibility of power supply, but also facilitates the high-efficiency access of energy storage and other devices through its DC port, forming an innovative AC / DC hybrid microgrid architecture.

[0018] 3. This invention determines the energy storage capacity and power based on multi-condition time-series simulation and formulates differentiated charging and discharging strategies, enabling energy storage to play a key role in peak shaving during the tea-making season and in filling valleys and smoothing out peaks during normal times, which greatly improves the comprehensive utilization rate of energy storage equipment and the economic efficiency of the project.

[0019] 4. This invention achieves real-time coordination and distribution-microgrid collaboration among power sources, grid, load, and energy storage through a three-layer microgrid energy management system. In particular, strategies such as heavy overload collaborative control embody proactive distribution network thinking and improve the overall system's safety and stability. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall architecture of the integrated hydro-solar-storage microgrid system provided in an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the AC / DC flexible interconnection device in an embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] This invention provides a microgrid system integrating hydropower, photovoltaic power, and energy storage, including distributed hydropower, distributed photovoltaic power, energy storage system, medium-voltage AC / DC flexible interconnection device, microgrid energy management system, and load.

[0026] The medium-voltage AC / DC flexible interconnection device is the core hub of the system, connected in series between the microgrid's 10kV grid connection point and the upper-level distribution network. This device has both AC and DC ports: the AC port enables flexible power flow between the microgrid and the upper-level distribution network, allowing for rapid and stepless adjustment of the magnitude and direction of power exchange according to control commands; the DC port directly and efficiently connects to the energy storage system, forming a hybrid AC / DC power supply architecture, reducing energy conversion stages and improving overall efficiency.

[0027] The microgrid energy management system, acting as the "brain" of the system, connects to the distributed hydropower, distributed photovoltaic power, energy storage system, and medium-voltage AC / DC flexible interconnection device via a communication network. It is responsible for collecting real-time operating data (such as power, voltage, and status) of the entire system and, based on built-in optimization algorithms and execution strategies, coordinating and controlling the aforementioned controllable devices. This enables optimized operation of the microgrid in grid-connected mode, autonomous and stable operation in off-grid mode, and friendly interaction and coordinated scheduling with the upper-level distribution network.

[0028] like Figure 1 As shown, this embodiment provides an example of a hydro-solar-storage integrated microgrid system, which is constructed in a core tea-producing area in Wuyishan, Fujian Province. The system includes: Distributed power generation: There is currently one small hydropower station in Huangbai with an installed capacity of 800kW and a total of approximately 236.48kWp (to be increased to 256.24kWp in the long term) of residential distributed photovoltaic power generation.

[0029] Energy storage system: It adopts a containerized integrated design and is equipped with a lithium iron phosphate battery system with a capacity of 300kW / 626kWh.

[0030] Medium-voltage AC / DC flexible interconnection device: rated capacity of 3MVA (AC mutual assistance), DC port capacity of 1MVA, rated voltage of 1500V. This device is connected in series to the grid connection point of the 10kV Niutoudun branch line.

[0031] Load: Mainly the load supplied by this branch line for residential use and numerous tea factories. The maximum load during the tea-making season can reach over 2.5MW.

[0032] Microgrid energy management system: Deployed in the monitoring compartment inside the energy storage container.

[0033] The upstream power distribution network is powered through the 10kV Xialin line of the 35kV substation.

[0034] The medium-voltage AC / DC flexible interconnection device specifically includes a parallel transformer, a series transformer, a parallel-side inverter, a series-side inverter, and a bypass module. The parallel transformer is connected in parallel to the line, supplying power to the parallel-side inverter and supporting the stability of the DC bus voltage. The series transformer is connected in series to the line, and its secondary voltage is controlled by the series-side inverter. By adjusting the amplitude and phase difference of this voltage, precise and flexible control of the power flow between lines can be achieved. The bypass module, composed of anti-parallel thyristors and contactors, is a key fault protection component. When a short-circuit fault is detected in the line, the control system first triggers the thyristors to conduct, connecting the series reactor to the fault circuit in a very short time to limit the surge in short-circuit current; subsequently, the contactor closes, forming a stable bypass channel; simultaneously, the high-speed permanent magnet vacuum circuit breaker (operating time 10-20ms) configured inside the device quickly trips, disconnecting the device from the faulty line, thereby preventing fault propagation and ensuring device safety. This protection logic ensures that the flexible interconnection device does not change the operating characteristics of the original distribution network protection during a fault.

[0035] The rated voltage of the DC port of the medium-voltage AC / DC flexible interconnection device is set to 1500V. The energy storage system is directly connected to this 1500V DC bus via a dedicated DC converter. This design enables the energy storage system to be "plug and play," simplifies the access structure, and is particularly suitable for energy storage units deployed in container form, facilitating rapid deployment and expansion.

[0036] like Figure 2 As shown, the medium-voltage AC / DC flexible interconnection device in this embodiment specifically includes: a parallel transformer PIT, a series transformer SIT, a parallel-side inverter PCM, a series-side inverter SCM, a bypass module CRM (including thyristors and contactors), and fast vacuum circuit breakers QF1 and QF2. The energy storage system is connected to the device's 1500V DC bus via a DC / DC converter.

[0037] The configured capacity of the energy storage system is not arbitrarily set, but determined based on multi-condition and time-series power balance analysis of the typical daily load curves of the microgrid throughout the year and the output curves of distributed power sources (hydropower and solar power). The analysis conditions must cover at least the peak tea-making season in spring, the non-tea-making season in spring, and the typical days in autumn (non-high-water season). The core objective of the configuration is to smooth out the peak-valley difference of the daily net load and maximize the local absorption rate of distributed hydropower and photovoltaic power, rather than simply dealing with power fluctuations. The energy storage system preferably adopts a containerized integrated design, highly integrating lithium iron phosphate battery clusters, battery management systems, DC converters, fire protection systems, and temperature control systems, possessing good mobility and environmental adaptability.

[0038] The microgrid energy management system adopts a clear hierarchical control architecture, including: a local control layer, consisting of controllers deployed locally on energy storage systems, flexible interconnect devices, and other equipment, responsible for executing millisecond- to second-level fast closed-loop control and data acquisition; a centralized control layer, which is the microgrid energy management system master station, responsible for monitoring the overall network operation status, calculating advanced application functions (such as optimized scheduling, energy management, and fault analysis), and generating control commands to be issued to the local layer; and a scheduling layer, referring to the upper-level distribution master station system, which issues scheduling commands (such as total switching power plan) to the microgrid energy management system from the perspective of the distribution network as a whole, realizing the global resource optimization allocation of the distribution network and the microgrid.

[0039] The present invention also provides a control method for the above-mentioned integrated hydro-solar-storage microgrid system, comprising the following steps: S1: The microgrid energy management system collects in real time the load power, distributed hydropower and photovoltaic output, state of charge (SOC) of the energy storage system, the switching power at the grid connection point, and the dispatch instructions of the upper-level distribution network within the microgrid.

[0040] S2: Based on the operational data, combined with historical data and calendar information, determine the typical operating conditions of the system at present, such as the peak tea-making season in spring, the non-tea-making season in spring, or a typical day during the non-flood season.

[0041] S3: Based on the determined current operating conditions, call and execute the corresponding optimized control strategy combination from the preset strategy library. These strategies include at least the setting of the energy storage system's charging and discharging power curve, the power mutual assistance setting value of the medium-voltage AC / DC flexible interconnection device, and the output control strategy of photovoltaic power generation (such as anti-reverse current limiting).

[0042] When the current operating conditions are determined to be the peak tea-making season in spring, the energy storage system's charging and discharging strategy is set as follows: From early morning to midday (e.g., 0:00-12:00), when the load is relatively low and photovoltaic power generation may begin, the energy storage system is controlled to charge, storing as much electrical energy as possible; during the afternoon to evening (e.g., 16:00-21:00), the peak tea-making load period, the energy storage system is controlled to discharge at its maximum allowable power, directly supplying power to the local load, thereby significantly reducing the peak power absorbed from the main grid. Under this condition, the medium-voltage AC / DC flexible interconnection device mainly operates in "power receiving" mode, smoothly and controllably absorbing the required power from the upper-level distribution network based on the real-time power deficit within the microgrid, avoiding impact on the upper-level grid.

[0043] When the current operating condition is determined to be a typical day during a non-high-water season (such as autumn), hydropower output is relatively low and the load is relatively stable. In this case, the energy storage system's charging and discharging strategy is set to execute a classic intraday "charge-discharge" mode: charging typically occurs during midday (e.g., 11:00-14:00) when photovoltaic output is at its peak, or during nighttime load troughs; discharging occurs during evening load peaks (e.g., 18:00-22:00). The main purpose of this is to smooth out intraday fluctuations in the microgrid's net load (total load minus distributed power output), making the grid connection point's power exchange curve flatter. Under this condition, the medium-voltage AC / DC flexible interconnection device mainly operates in "power smoothing" mode, coordinating with energy storage operations to maintain stable power exchange at the grid connection point.

[0044] The control method also includes a heavy overload collaborative control step: when the microgrid energy management system detects a heavy overload alarm on a critical line within the microgrid, or learns through communication that a connected upstream distribution network line has an overload alarm, the collaborative control process is immediately initiated. First, the energy storage system is prioritized to release its stored electrical energy to provide rapid power support; if the energy storage support power is still insufficient, a portion of the power is flexibly transferred from the upstream distribution network or other non-heavy-load lines interconnected through the medium-voltage AC / DC flexible interconnection device; as a last resort, if the distributed photovoltaic output is large at this moment and exacerbates the overload caused by reverse power flow, a power reduction operation command can be issued to the photovoltaic inverter.

[0045] The microgrid energy management system communicates with the upstream distribution master station system using 5G power virtual private network technology. Leveraging its low latency, high reliability, and secure isolation characteristics, it reliably transmits dispatch commands and operational status information. Simultaneously, the system communicates with distributed photovoltaic inverters via wireless public networks or fiber optics, enabling centralized monitoring and flexible control of a large number of residential photovoltaic systems.

[0046] In summary, this invention, through innovative design combining hardware and software, constructs an adaptive, highly flexible, green, and efficient integrated microgrid of water, solar, and energy storage, providing a replicable and scalable solution for regions with similar characteristics.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A microgrid system integrating hydro-solar-storage, characterized in that, include: Distributed hydropower, distributed photovoltaic power, energy storage systems, medium-voltage AC / DC flexible interconnection devices, microgrid energy management systems, and loads; The medium-voltage AC / DC flexible interconnection device is connected in series between the grid connection point of the microgrid and the upper-level distribution network. Its AC port is used to realize flexible power flow mutual assistance between the microgrid and the upper-level distribution network, and its DC port is used to connect to the energy storage system. The microgrid energy management system is communicatively connected to the distributed hydropower source, distributed photovoltaic power source, energy storage system, and medium-voltage AC / DC flexible interconnection device. It is used to collect system operation data and execute optimized control strategies to realize the autonomous operation of the microgrid and coordinated control with the upper-level distribution network.

2. The integrated hydro-solar-storage microgrid system according to claim 1, characterized in that, The medium-voltage AC / DC flexible interconnection device includes a parallel transformer, a series transformer, a parallel-side inverter, a series-side inverter, and a bypass module. The primary side of the parallel transformer is connected to the line in parallel, and the secondary side is connected to the inverter on the parallel side, which is used to provide AC power and support DC bus voltage. The primary side of the series transformer is connected in series to the line, and the secondary side is connected to the series-side inverter. The directional flow and stepless regulation of power flow are achieved by adjusting the amplitude and phase of the secondary voltage. The bypass module consists of anti-parallel thyristors and contactors. When a short-circuit fault occurs in the line, the thyristors conduct first, and then the contactors close, connecting the series reactor to the fault circuit to achieve current limiting protection. At the same time, the permanent magnet vacuum circuit breaker inside the device trips and disconnects within 10-20ms.

3. The integrated hydro-solar-storage microgrid system according to claim 2, characterized in that, The rated voltage of the DC port of the medium-voltage AC / DC flexible interconnection device is 1500V. The energy storage system is directly connected to the DC port at 1500V DC through a DC converter, realizing plug-and-play functionality.

4. The integrated hydro-solar-storage microgrid system according to claim 1, characterized in that, The configuration capacity of the energy storage system is determined based on multi-condition power balance analysis of the typical daily load curve of the microgrid and the output curve of the distributed power source. The configuration goal is to smooth the peak-valley difference of the daily load and improve the local consumption rate of distributed energy. The energy storage system adopts a containerized integrated design and has built-in lithium iron phosphate battery clusters, battery management system, DC converter and fire protection and temperature control system.

5. The integrated hydro-solar-storage microgrid system according to claim 1, characterized in that, The microgrid energy management system adopts a hierarchical control architecture, including: The local control layer consists of local controllers deployed in energy storage systems and flexible interconnected devices, which are responsible for data acquisition and rapid closed-loop control of the underlying equipment. The centralized control layer deploys the microgrid energy management system to integrate network-wide data, monitor operational status, calculate optimized scheduling algorithms, and issue control commands to the local control layer. The dispatch layer, which is the upper-level distribution master station system, is used to issue macro-dispatch instructions to the microgrid energy management system to achieve global collaborative optimization between the distribution network and the microgrid.

6. The control method for the integrated hydro-solar-storage microgrid system according to any one of claims 1-5, characterized in that, Includes the following steps: S1: The microgrid energy management system collects in real time the load power, distributed hydropower and photovoltaic output, energy storage system status, grid connection point exchange power, and dispatch instructions from the upper-level distribution network within the microgrid; S2: Based on the operating data, determine the current operating condition of the system, which includes at least typical days during the peak tea-making season in spring, the non-tea-making season in spring, and the non-high-water season; S3: Based on the current operating conditions, execute the corresponding optimized control strategy, which includes the energy storage system charging and discharging strategy, the power mutual assistance strategy of the medium-voltage AC / DC flexible interconnection device, and the photovoltaic output control strategy.

7. The control method for the integrated hydro-solar-storage microgrid system according to claim 6, characterized in that, When it is determined that the current operating conditions are during the peak tea-making season in spring, the energy storage system's charging and discharging strategy is as follows: charging is carried out during the period from early morning to noon when the load is relatively low or the photovoltaic output is relatively high, and discharging is carried out during the peak tea-making load period from afternoon to evening in order to reduce the peak load; the medium-voltage AC / DC flexible interconnection device controls the rate and magnitude of power absorption from the upper-level distribution network according to the power deficit inside the microgrid.

8. The control method for the integrated hydro-solar-storage microgrid system according to claim 6, characterized in that, When it is determined that the current day is a typical day under non-high water season conditions, the energy storage system charging and discharging strategy is as follows: execute the intraday "one charge and one discharge" mode, charge during the midday photovoltaic peak period or the nighttime load off-peak period, and discharge during the evening load peak period to smooth out intraday net load fluctuations; the medium-voltage AC / DC flexible interconnection device is mainly used to maintain the stability of power exchange at the grid connection point.

9. The control method for the integrated hydro-solar-storage microgrid system according to claim 6, characterized in that, It also includes heavy overload collaborative control steps: When a severe overload is detected in the microgrid or in the associated distribution network lines, the energy storage system is prioritized to discharge and provide supporting power. If the energy storage system is insufficient, the power can be flexibly supplemented from the upper-level distribution network or adjacent non-heavy-loaded lines through the medium-voltage AC / DC flexible interconnection device. If the reverse transmission of distributed photovoltaic power exacerbates the heavy load, then power reduction control should be implemented for the photovoltaic system.

10. The control method for the integrated hydro-solar-storage microgrid system according to claim 6, characterized in that, The microgrid energy management system communicates with the upper-level power distribution station system through a 5G power virtual private network, receives dispatch instructions, and uploads the microgrid's adjustable capacity, operating status, and abnormal information. At the same time, it communicates with distributed photovoltaic inverters via wireless networks or optical fibers to collect data and issue start / stop and power control instructions.

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