Automatic switching confluence device of optical-storage-diesel hybrid system

Abstract

The embodiment of the invention provides an automatic switching convergence device of an optical-storage-diesel hybrid system. The automatic switching convergence device comprises a first automatic switching switch and a second automatic switching switch, a first load end of the first automatic change-over switch is used for being connected with an important load, a first frequently-used power supply end is used for being connected with a hybrid inverse load interface, and a first standby power supply end is used for being connected with a hybrid inverse power grid interface; a second load end of the second automatic change-over switch is used for being connected with a secondary load and the first standby power supply end, a second common power supply end is used for being connected with the power grid, and a second standby power supply end is used for being connected with the diesel generator. According to the embodiment of the invention, simultaneous access of each device of the optical-storage-diesel hybrid system can be satisfied, the operation mode can be automatically switched under different power supply environments and power supply requirements through the automatic change-over switch and the related EMS strategy, the application environment range is wide, especially the power system of which the main power grid is unstable or cannot be accessed to the main power grid, and the power supply efficiency is improved. And the overall safety and stable operation of the system are ensured.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of photovoltaic-storage-diesel hybrid systems, and specifically relate to an automatic switching confluence device for photovoltaic-storage-diesel hybrid systems. Background Art

[0002] Under the severe challenge of global climate change, exploring sustainable, clean and efficient energy solutions has become the common responsibility and mission of all mankind. With its unique advantages, energy storage systems are gradually showing their great potential as a component of the future energy network, which will help to form a greener, more reliable and resilient power system. The rapid development of energy storage technology has provided microgrids with more flexible and diverse energy storage solutions. Through intelligent control and optimized scheduling, microgrids can monitor the state of the grid in real time, predict load changes, optimize energy configuration, and achieve a dynamic balance between power generation, energy storage and load, thereby improving energy efficiency and economy.

[0003] With the continuous decline in the cost of renewable energy, the continuous advancement of energy storage technology and the widespread application of smart grid technology, the potential of microgrids has been further released. The power generation resources in microgrids are diverse, including traditional diesel generators and natural gas generators, as well as clean energy such as solar photovoltaic panels, small wind turbines, fuel cells, etc., forming a hybrid system that combines multiple energy sources and energy storage systems.

[0004] The current photovoltaic-storage-diesel hybrid system usually includes but is not limited to energy storage systems, photovoltaic systems, diesel generators, hybrid inverters, power grids, important loads and secondary loads. Under different power supply environments and power supply requirements, the automatic switching access of various parts of the system and related EMS strategies are important guarantees for the stable operation of the system. However, the application environment of energy storage systems is complex. In remote rural areas or isolated islands where the main power grid is unstable or cannot be connected to the main power grid, the existing power supply methods often cannot meet the needs of power supply safety and stability. Summary of the invention

[0005] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art, and provide an automatic switching merging device for a photovoltaic-storage-diesel hybrid system, wherein the photovoltaic-storage-diesel hybrid system includes a power grid, a diesel generator, a hybrid inverter, and a photovoltaic system and an energy storage system connected to the hybrid inverter.

[0006] The automatic switching confluence device of the photovoltaic-storage-diesel hybrid system comprises a first automatic switching switch and a second automatic switching switch;

[0007] The first load terminal of the first automatic switching switch is used to connect to an important load, the first common power terminal is used to connect to a mixed reverse load interface, and the first standby power terminal is used to connect to a mixed reverse grid interface;

[0008] The second load end of the second automatic switching switch is used to connect to the secondary load and the first backup power supply end respectively, the second common power supply end is used to connect to the power grid, and the second backup power supply end is used to connect to the diesel generator.

[0009] Furthermore, the hybrid grid interface is provided with a circuit breaker for closing when the grid is powered and opening when the grid is powered off.

[0010] Further, when the common power switch of the second automatic transfer switch is closed, the circuit breaker is closed;

[0011] When the backup power switch of the second automatic transfer switch is closed, the circuit breaker is opened.

[0012] Furthermore, when the power grid is out of power, if the photovoltaic system has sufficient power generation, the common power switch of the first automatic switching switch is closed, so that the photovoltaic system supplies power to the important load.

[0013] Furthermore, when the power grid is out of power, if the photovoltaic system does not generate enough electricity, the common power switch of the first automatic switching switch is closed to allow the energy storage system to supply power to the important load.

[0014] Furthermore, when the energy storage system supplies power to the important load, if the charging state of the energy storage system is lower than the lower limit protection threshold, the second automatic switching switch and the backup power switch of the second automatic switching switch are respectively closed and the diesel generator is started, so that the diesel generator supplies power to the important load and the secondary load.

[0015] Furthermore, the lower protection threshold is 20%.

[0016] Furthermore, when the diesel generator supplies power to the important load and the secondary load, if the charging state of the energy storage system is higher than the upper limit protection threshold, the diesel generator is shut down and the common power switch of the first automatic switching switch is closed, so that the hybrid inverter supplies power to the important load off-grid.

[0017] Furthermore, the upper limit protection threshold is 60%.

[0018] Furthermore, the device also includes an uninterruptible power supply; the uninterruptible power supply is arranged at the first load end.

[0019] An automatic switching merging device for a photovoltaic-storage-diesel hybrid system in an embodiment of the present disclosure can meet the simultaneous access of an energy storage system, a photovoltaic system, a diesel generator, a hybrid inverter, a power grid, important loads, and secondary loads. At the same time, it can automatically switch the operating mode under different power supply environments and power supply requirements through automatic switching switches and related EMS strategies. It has a wide range of applicable environments and can be applied to regional power systems where the main power grid is unstable or cannot be connected to the main power grid, to ensure the overall safety and stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a structural schematic diagram of an automatic switching merging device for a photovoltaic-storage-diesel hybrid system according to an embodiment of the present disclosure;

[0021] Figure 2 FIG. 4 is a schematic diagram of an EMS communication topology according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0023] In addition, the described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the present disclosure.

[0024] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0025] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another component. Therefore, the first component discussed below can be referred to as the second component without departing from the teachings of the concepts of the present disclosure. As used in this disclosure, the term "and / or" includes any one of the associated listed items and all combinations of one or more.

[0026] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present disclosure, and therefore cannot be used to limit the protection scope of the present disclosure.

[0027] like Figure 1 As shown, an embodiment of the present disclosure provides an automatic switching confluence device for a photovoltaic-storage-diesel hybrid system, wherein the photovoltaic-storage-diesel hybrid system comprises a power grid 100, a diesel generator 200, a hybrid inverter 300, and a photovoltaic system 400 and an energy storage system 500 connected to the hybrid inverter 300. The automatic switching confluence device comprises a first automatic switching switch ATS1 and a second automatic switching switch ATS2. The first load end (10) of the first automatic switching switch ATS1 is used to connect to an important load L1, the first common power end (11) is used to connect to a mixed inverter load interface (31), and the first backup power end (12) is used to connect to a mixed inverter power grid interface (32). The second load end (20) of the second automatic switching switch ATS2 is used to connect to a secondary load L2 and the first backup power end (12), respectively, the second common power end (21) is used to connect to the power grid 100, and the second backup power end (22) is used to connect to the diesel generator 200.

[0028] Specifically, an automatic transfer switch (ATS) is an electrical appliance used to switch a load circuit from one power source to another. A normal power switch and a backup power switch are usually provided inside the ATS. When one of the switches is closed, the other switch is opened, thereby selectively conducting the main circuit or the backup circuit.

[0029] When the grid 100 has power, the common power switch S21 in the second automatic switching switch ATS2 is closed, and its backup power switch S22 is disconnected. At the same time, the backup power switch S12 in the first automatic switching switch ATS1 is closed and its common power switch S11 is disconnected, so that the grid 100 supplies power to the important load L1 and the secondary load L2 at the same time. At the same time, the photovoltaic system 400 is connected to the grid for power supply through the hybrid inverter grid interface (32) of the hybrid inverter 300, and charges the energy storage system 500.

[0030] The hybrid inverter grid interface (32) is provided with a circuit breaker QF. When the grid 100 is powered, the circuit breaker QF is closed to allow the hybrid inverter 300 to be connected to the grid for power supply. On the contrary, when the grid 100 is powered off, the circuit breaker QF is disconnected to cut off the grid-connected power supply circuit of the hybrid inverter 300. The automatic switching confluence device of this embodiment is designed with electrical interlocking protection between the circuit breaker QF and the second automatic switching switch ATS2: when the normal power switch S21 of the second automatic switching switch ATS2 is closed and the backup power switch S22 is disconnected, the circuit breaker QF is closed; when the backup power switch S22 of the second automatic switching switch ATS2 is closed and the normal power switch S21 is disconnected, the circuit breaker QF is disconnected and cannot be closed.

[0031] When the power grid 100 is powered off, the automatic switching converging device of this embodiment can automatically switch to the following operating modes according to the power supply environment and power supply requirements:

[0032] If the photovoltaic system 400 generates sufficient power, that is, it can at least meet the power supply demand of the important load L1, the normal power switch S11 of the first automatic switching switch ATS1 is closed, and the backup power switch S12 is automatically disconnected. The photovoltaic system 400 supplies off-grid power to the important load L1 through the hybrid inverter load interface (31) of the hybrid inverter 300, and when the photovoltaic system 400 generates surplus power, the energy storage system 500 is charged through the hybrid inverter 300, or the excess power is fed back to the grid.

[0033] If the photovoltaic system 400 generates insufficient electricity to meet the power supply demand of the important load L1, the common power switch S11 of the first automatic switching switch ATS1 is kept closed, the energy storage system 500 is discharged, and the hybrid inverter 300 provides off-grid power to the important load L1 through the hybrid inverter load interface (31).

[0034] At this time, if the state of charge (SOC) of the energy storage system 500 is lower than the preset lower protection threshold, such as 20%, the backup power switches S12 and S22 of the second automatic switching switch ATS1 and the second automatic switching switch ATS2 are closed respectively and the diesel generator 200 is started, so that the diesel generator 200 supplies power to the important load L1 and the secondary load L2. At the same time, the photovoltaic system 400 charges the energy storage system 500.

[0035] When the energy storage system 500 is charged to a preset upper protection threshold, such as 60%, the diesel generator 200 is shut down and the common power switch S11 of the first automatic switching switch ATS1 is closed, and the photovoltaic system 400 and the energy storage system 500 re-supply off-grid power to the important load L1 through the hybrid inverter 300.

[0036] When the power grid is restored, the diesel generator 200 is shut down, the first automatic switching switch ATS1 switches to the standby power supply terminal (12), the second automatic switching switch ATS2 switches to the normal power supply terminal (21), the circuit breaker QF is closed, and the hybrid inverter 300 is switched back to the grid-connected power supply mode.

[0037] For example, Figure 1 As shown, the automatic switching confluence device of the photovoltaic-storage-diesel hybrid system of the embodiment of the present disclosure also includes an uninterruptible power supply UPS. The uninterruptible power supply UPS is arranged at the first load end (10), that is, the interface of the important load L1, and is used to provide short-term power supply to the important load L1 when other components of the device fail, and to ensure the power supply stability of the important load L1 when the power grid suddenly loses power or the device operation mode is switched, so as to help the system operate stably.

[0038] It should be noted that the switching of the above operating modes can be achieved through EMS (Energy Management System) and pre-set related EMS strategies. Figure 2 As shown, the UPS and EMS are connected by RS232 communication line, the meter and hybrid inverter, the hybrid inverter and EMS, the IO module and EMS are connected by RS485 communication line, the BMS and EMS are connected by network cable, the diesel generator and hybrid inverter, the busbar and hybrid inverter, the busbar and BMS, the BMS and hybrid inverter are connected by dry contacts, and various control feedback signals of the IO module to external devices such as ATS, circuit breakers, etc. are also transmitted through dry contacts.

[0039] An automatic switching merging device for a photovoltaic-storage-diesel hybrid system in an embodiment of the present disclosure can meet the simultaneous access of an energy storage system, a photovoltaic system, a diesel generator, a hybrid inverter, a power grid, important loads, and secondary loads. At the same time, it can automatically switch the operating mode under different power supply environments and power supply requirements through automatic switching switches and related EMS strategies. It has a wide range of applicable environments and can be applied to regional power systems where the main power grid is unstable or cannot be connected to the main power grid, to ensure the overall safety and stable operation of the system.

[0040] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. An automatic switching confluence device for a photovoltaic-storage-diesel hybrid system, the photovoltaic-storage-diesel hybrid system comprising a power grid, a diesel generator, a hybrid inverter, and a photovoltaic system and an energy storage system connected to the hybrid inverter, characterized in that: The device comprises a first automatic switching switch and a second automatic switching switch; The first load terminal of the first automatic switching switch is used to connect to an important load, the first common power terminal is used to connect to a mixed reverse load interface, and the first standby power terminal is used to connect to a mixed reverse grid interface; The second load end of the second automatic switching switch is used to connect to the secondary load and the first backup power supply end respectively, the second common power supply end is used to connect to the power grid, and the second backup power supply end is used to connect to the diesel generator.

2. The device according to claim 1, characterized in that The hybrid grid interface is provided with a circuit breaker for closing when the grid is powered and opening when the grid is powered off.

3. The device according to claim 2, characterized in that When the common power switch of the second automatic transfer switch is closed, the circuit breaker is closed; When the backup power switch of the second automatic transfer switch is closed, the circuit breaker is opened.

4. The device according to claim 1, characterized in that When the power grid is out of power, if the photovoltaic system has sufficient power generation, the common power switch of the first automatic transfer switch is closed to enable the photovoltaic system to supply power to the important load.

5. The device according to claim 1, characterized in that When the power grid is out of power, if the photovoltaic system does not generate enough electricity, the common power switch of the first automatic switching switch is closed to allow the energy storage system to supply power to the important load.

6. The device according to claim 5, characterized in that When the energy storage system supplies power to the important load, if the charging state of the energy storage system is lower than the lower limit protection threshold, the second automatic switching switch and the backup power switch of the second automatic switching switch are respectively closed and the diesel generator is started, so that the diesel generator supplies power to the important load and the secondary load.

7. The device according to claim 6, characterized in that The lower protection threshold is 20%.

8. The device according to claim 6, characterized in that When the diesel generator supplies power to the important load and the secondary load, if the charging state of the energy storage system is higher than the upper limit protection threshold, the diesel generator is shut down and the common power switch of the first automatic switching switch is closed, so that the hybrid inverter supplies power to the important load off-grid.

9. The device according to claim 8, characterized in that The upper limit protection threshold is 60%.

10. The device according to any one of claims 1 to 9, characterized in that The device also includes an uninterruptible power supply; the uninterruptible power supply is arranged at the first load end.

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