A microgrid system

Abstract

The application provides a micro-grid system. The system comprises a first photovoltaic power generation system, an alternating current bus, an uninterrupted power system (UPS), a first switch and a second switch. When the photovoltaic power generation system has power generation conditions, the first photovoltaic power supply system directly or indirectly supplies power to the UPS, and after the UPS is activated, the UPS supplies power to the supervision, control and other units of the micro-grid system, so that the system controller can control other energy storage power supply systems and photovoltaic power generation systems in the micro-grid to start, thereby realizing self-starting recovery of the entire micro-grid to a normal and stable operation state.

Description

TECHNICAL FIELD

[0001] The present application relates to a micro-grid system. BACKGROUND

[0002] The micro-grid system coupled with light and storage is always the mainstream micro-grid system structure due to its good scalability and other advantages. Due to the sudden conditions such as voltage fluctuation and fault ride-through in the operation of the micro-grid system, the secondary monitoring system such as the micro-grid controller, the sub-array sampling, and the battery control device in the micro-grid system generally needs to be powered by the UPS or directly powered from the micro-grid to ensure its operation.

[0003] When the micro-grid encounters bad weather and the energy in the energy storage system is insufficient, the micro-grid cannot continue to maintain system operation, so the micro-grid has two options: 1) configure a diesel generator to maintain power supply; 2) shut down the micro-grid, reserve enough SOC (State of Charge) of the energy storage, support the consumption of power after black start, and wait until the next morning when the weather recovers and the PV(Photo Voltaic) can generate power before starting operation.

[0004] The diesel generator set has a large amount of operation and maintenance work, high technical ability requirement, complex management, and high oil cost, which is not conducive to the use in some remote or underdeveloped areas, and oil-free is a preferred power supply scheme for such areas.

[0005] However, after the micro-grid is powered off due to failure or insufficient energy, the UPS and the micro-grid monitoring system will also be powered off soon, and in the case that the conditions are met (light recovery) the next day, the micro-grid system lacks the ability or mechanism for self-starting and self-recovery, and can only continue to be in a power-off state, or has to rely on the operation and maintenance personnel to restart the micro-grid system, so that the micro-grid has high power-off and operation and maintenance costs, especially for small low-voltage micro-grid systems, which faces great operation and maintenance pressure and poor user experience.

[0006] It is necessary for the light and storage AC coupled micro-grid to be able to start and recover itself in time after the micro-grid has the conditions for recovery. SUMMARY

[0007] In order to solve the problem that the existing micro-grid black start method relies on the remaining power of the battery and the remaining oil of the diesel generator, the present application provides a micro-grid system.

[0008] In a first aspect, in a first possible implementation, the application provides a micro-grid system, comprising: a first photovoltaic power generation system, an AC bus, a UPS (Uninterrupted Power System), a first switch and a second switch; the first photovoltaic power generation system comprises at least one first photovoltaic power generation unit and at least one first photovoltaic inverter, is connected with the UPS through the first switch, and is connected with the AC bus through the second switch, and is used for supplying power to the UPS through the first switch or supplying power to the AC bus through the second switch; the AC bus is connected with the UPS through the first switch, and is used for supplying power to the UPS when powered on.

[0009] It can be understood that the self-starting process of the micro-grid usually goes through several steps, and the starting of each unit is realized in sequence, and finally the whole micro-grid starts to operate normally. The UPS is usually used to provide stable and uninterrupted alternating current, and it is usually configured with a battery to ensure that it can maintain uninterrupted and stable alternating current output for a period of time when the external power supply is unstable or stopped. During the non-working period of the micro-grid, such as the photovoltaic power generation system without power generation conditions at night and the energy storage system also lacks power to supply power to the micro-grid, the micro-grid cannot work, and the control and management units in the micro-grid continue to maintain a working time by the UPS, but when the power of the battery in the UPS is consumed, the UPS also stops supplying power to them, at this time, the whole micro-grid system including the control and management units stops running. When the micro-grid has operating conditions, such as sufficient sunlight during the day, the operation of the micro-grid needs to be restarted, and first of all, the control and management units in the system, such as the system controller in the embodiment of the application, are activated, and after the control and management units in the micro-grid are powered on and activated, the corresponding starting control can be taken according to the specific conditions of the power generation system (such as the photovoltaic power generation system in the embodiment of the application) and the energy storage system (such as the energy storage power supply system in the embodiment of the application) in the micro-grid, so that the micro-grid recovers to the normal power supply state. In the embodiment of the application, the UPS is usually automatically activated directly or indirectly when the photovoltaic power generation system has power generation capacity, and then the control and management units are activated by the UPS, and then the photovoltaic power generation system and the energy storage power supply system are activated, and finally the self-starting of the micro-grid is realized. It should be understood that there can be multiple photovoltaic power generation systems in the power supply system of the micro-grid, which generally supply power to the alternating current bus directly, and the embodiment of the application draws a power supply line from one of the photovoltaic power generation systems to the UPS, so that the photovoltaic power generation system can supply power to the UPS in addition to supplying power to the alternating current bus. When the photovoltaic power generation system has power generation capacity, the UPS can be activated first, and then the system controller can be activated by the UPS, and the system controller can determine the timing of restarting the micro-grid according to the overall situation of the other photovoltaic power generation systems and the energy storage power supply system, and the micro-grid can be restarted when the power supply of light and storage is sufficient. This system architecture design that can realize the self-starting of the micro-grid system ingeniously utilizes the function of the photovoltaic power generation system to generate power independently, without the need for excessive adjustment of the micro-grid system or the need for additional configuration of other power supply equipment or controllers, and can realize the self-starting function of the micro-grid system at the lowest cost. It should be understood that the first photovoltaic power generation system in the embodiment of the application can be any one of the photovoltaic power generation systems, and in actual application, the first photovoltaic power generation system needs to be used to activate the UPS directly through a relay, and can be set to a position close to the UPS to save line cost and current transmission loss.

[0010] In combination with the first possible implementation of the first aspect, in a second possible implementation, the first switch comprises a first contact KA1 and a second contact KA2; the first photovoltaic power generation system is connected with the UPS through the second contact KA2; and the AC bus is connected with the UPS through the first contact KA1.

[0011] In combination with the first or second possible implementation of the first aspect, in a third possible implementation, the first contact KA1 is configured to be opened when the AC bus is powered off and closed when the AC bus is powered on; and the second contact KA2 is configured to be closed when the AC bus is powered off and opened when the AC bus is powered on.

[0012] In combination with the second or third possible implementation of the first aspect, in a fourth possible implementation, when the available power generation of the first photovoltaic power generation system is greater than a first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the AC bus through the second switch, so that the AC bus supplies power to the UPS through the first contact KA1; or when the available power generation of the first photovoltaic power generation system is greater than or equal to the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the UPS through the second contact KA2.

[0013] In combination with the fourth possible implementation of the first aspect, in a fifth possible implementation, if the second switch is in an open state, when the available power generation of the first photovoltaic power generation system is greater than or equal to the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the UPS through the second contact KA2.

[0014] In combination with the fourth possible implementation of the first aspect, in a sixth possible implementation, if the second switch is in a closed state, when the available power generation of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the AC bus through the second switch, so that the AC bus supplies power to the UPS through the first contact KA1.

[0015] It should be understood that, if the second switch is a normally closed switch, when the AC bus is in a powered-off state, the second switch is in a closed state; and when the available power generation of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold and starts to supply power, the AC bus is rapidly powered on, the first contact KA1 of the relay is turned on, and the second contact KA2 is opened, at this time, the first photovoltaic power generation system indirectly supplies power to the UPS through the AC bus; if the second switch is a normally open switch, when the AC bus is in a powered-off state, the second switch is in an open state; and when the available power generation of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold and starts to supply power, the supplied current flows to the UPS through the second contact KA2, so that the UPS is powered on.

[0016] It should be noted that the design of the relay is not only to realize the two scenarios that the first photovoltaic power generation system directly or indirectly supplies power to the UPS, but also to automatically switch to the state that the first contact KA1 is disconnected and the second contact KA2 is conducted when the circuit on the AC bus side fails during the operation of the micro-grid, which not only ensures the safety of other units of the micro-grid, but also maintains the power supply to the UPS, that is, maintains the power supply to the monitoring and management system, so as to continue to observe the whole micro-grid through the monitoring and management system.

[0017] In combination with any one of the first to sixth possible embodiments of the first aspect, in a seventh possible embodiment, at least one second photovoltaic power generation system and a system controller are further included; the UPS is connected with the system controller and used to supply power to the system controller; each second photovoltaic power generation system includes at least one second photovoltaic power generation unit and at least one second photovoltaic inverter, and is used to supply power to the AC bus; and the system controller is used to control the first photovoltaic power generation system and / or the second photovoltaic power generation system to supply power to the AC bus.

[0018] It should be understood that the micro-grid system can have multiple photovoltaic power generation systems, so that the micro-grid has more sufficient power supply sources; in addition, by configuring the system controller, the photovoltaic power generation systems can be better monitored and controlled, so as to realize flexible scheduling of power supply in the micro-grid. In the possible embodiments provided in the present application, one of the photovoltaic power generation systems, i.e., the first photovoltaic power generation system, is selected to have a self-starting function, so that when the available power generation power of the first photovoltaic power generation system reaches the first power supply threshold, the first photovoltaic power generation system automatically supplies power to the AC bus or the UPS, so that the UPS can supply power to the system controller, so that the system controller can quickly recover to work when the system and the external environment meet the conditions for the photovoltaic power generation system to supply power to the outside, and then the system controller can further control the other photovoltaic power generation system, i.e., the second photovoltaic power generation system, to supply power to the AC bus according to the pre-set conditions or human control. At this time, if the line between the first photovoltaic power generation system and the AC bus is not conducted, i.e., the second switch is in the disconnected state, the system controller can control the second switch to be closed synchronously, so that the first photovoltaic power generation system can also supply power to the AC bus, and then the UPS takes power from the AC bus.

[0019] In combination with any one of the first to seventh possible embodiments of the first aspect, in an eighth possible embodiment, the system further comprises at least one energy storage power supply system; the energy storage power supply system comprises at least one energy storage unit and at least one energy storage converter, and is configured to supply power to or receive power from the AC bus; and the system controller is further configured to control the energy storage power supply system to supply power to the AC bus, or to control the AC bus to supply power to the energy storage power supply system.

[0020] It should be understood that the energy storage power supply system can also be provided in the micro-grid to maintain stable power supply of the micro-grid when the photovoltaic power generation system cannot generate power at night or generates insufficient power due to poor weather conditions. Therefore, when the energy storage capacity of the energy storage power supply system is sufficient, the system controller can dispatch the energy storage power supply system to supply power to the AC bus; if the energy storage capacity of the energy storage power supply system is insufficient, the system controller can also supply power to the energy storage power supply system from the AC bus, and when the energy storage capacity is sufficient, the energy storage power supply system can be used to supply power to the AC bus.

[0021] In combination with the eighth possible embodiment of the first aspect, in a ninth possible embodiment, the system controller is configured to: when the sum of the available power generation of the first photovoltaic power generation system and the second photovoltaic power generation system is greater than the second photovoltaic power supply threshold, control the first photovoltaic power generation system and / or the second photovoltaic power generation system to supply power to the AC bus, and control the AC bus to supply power to the energy storage power supply system to make the energy storage power supply system return to the running state.

[0022] It should be understood that the energy storage power supply system will generate a certain power consumption during operation. Therefore, in order to further start the energy storage power supply system, the available power generation of all photovoltaic power generation systems needs to cover the power consumption of the energy storage power supply system, and the start under this condition can ensure that the overall operation of the micro-grid will not be in a power deficit state.

[0023] In combination with the eighth or ninth possible embodiment of the first aspect, in a tenth possible embodiment, the system controller is configured to: when the energy storage power supply system is in the running state, if the energy storage capacity of the energy storage power supply system is greater than or equal to the energy storage power supply threshold, control the energy storage power supply system to supply power to the AC bus; or, when the energy storage power supply system is in the running state, if the energy storage capacity of the energy storage power supply system is less than the energy storage power supply threshold, control the AC bus to charge the energy storage power supply system.

[0024] It should be understood that after the energy storage power supply system resumes operation, the SOC (State of Charge) of the energy storage unit of the energy storage power supply system also needs to be considered to determine whether to control it to supply power externally or to charge it externally. In a possible embodiment provided by the present application, the system controller will further determine whether to control the energy storage power supply system to supply power to the AC bus or to control the AC bus to charge the energy storage power supply system according to the energy storage amount of the energy storage power supply system, that is, the SOC of the energy storage unit of the energy storage power supply system.

[0025] The micro-grid system provided by the embodiments of the present application can automatically restore the operation of the monitoring and control system first when the light recovers after the micro-grid is powered off, without manual operation and maintenance, and by setting the start time of each unit of the system, the AC coupled light storage power generation system can maximize the use of the electric energy in the energy storage battery, without worrying about the problem of not being able to start after power failure. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a micro-grid system provided by the embodiments of the present application;

[0027] Figure 2 is another micro-grid system provided by the embodiments of the present application;

[0028] Figure 3 is still another micro-grid system provided by the embodiments of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the technical scheme of the present application more clear and explicit, the embodiments of the technical scheme of the present application will be described in detail below with reference to the drawings. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0030] The micro-grid system is usually used for continuous and stable power supply to various types of loads in an off-grid (separated from the power grid) state. Of course, the micro-grid can also have a grid-connected (connected to the power grid) scenario, and the embodiments of the present application do not make specific limitations. The ultimate source of power supply of the micro-grid is photovoltaic power generation. By configuring a photovoltaic power generation system, the direct current generated by the solar photovoltaic panel is converted into alternating current input to the power grid, and then the power grid supplies power to the load. In some scenarios, the micro-grid will also match some energy storage systems. When the photovoltaic power generation has a surplus, the surplus power is stored by the energy storage system. When the photovoltaic power generation is insufficient or zero, the energy storage system supplies power to the micro-grid, realizing stable power supply of the micro-grid. The mutual scheduling of such power supply needs to be dispatched by a control center (such as a monitoring and management system), and the normal operation of the micro-grid needs to be based on the normal operation of the control center.

[0031] The micro-grid system provided by the application is suitable for the problem that the micro-grid cannot automatically start and recover power supply after the micro-grid is powered off and the light recovers, and further, in the starting process, the time for starting the light storage device to recover operation can be accurately determined, and the power consumption of blind starting or the insufficient power generation capacity of the light storage device can be reduced.

[0032] In some micro-grids, if the power grid is powered off, all devices in the power grid are in a power shortage state, and even if the photovoltaic power generation system recovers power generation capacity, the monitoring and control system cannot automatically recover operation without external power supply, so the light storage system cannot control the micro-grid to normally supply power. After the power grid system is powered off, when the light makes the photovoltaic power generation system recover power generation capacity, a photovoltaic power generation system is used to establish a voltage, and a relay branch is used to supply power to the UPS, the monitoring and control system is powered on and operated, and the available power generation capacity of the photovoltaic power generation system is further evaluated. When the power generation capacity reaches a predetermined threshold, under the control of the control system, the AC bus voltage and the light storage system are gradually recovered, and the normal operation of the micro-grid is recovered, so as to normally supply power to the external load.

[0033] In the embodiments provided by the application, the photovoltaic power generation system can not only supply power to the micro-grid in the process of normal operation of the micro-grid, but also supply power to the UPS when the photovoltaic power generation system has power generation capacity after the micro-grid is powered off, the UPS supplies power to the system controller, and finally the micro-grid is self-recovered and self-started under the control of the system controller.

[0034] Drawings of the specification Figure 1 An exemplary micro-grid system provided by the embodiments of the application is shown. Figure 1 As shown in the figure, the system includes a first photovoltaic power generation system, an AC bus, an UPS (Uninterrupted Power System, uninterruptible power supply), a first switch and a second switch.

[0035] As shown in the figure, Figure 1As shown, the first photovoltaic power generation system includes a first photovoltaic power generation unit and a first photovoltaic inverter, and of course, there can be multiple first photovoltaic power generation units and multiple first photovoltaic inverters, and the embodiments of the present application do not make specific limitations thereto. The first photovoltaic power generation system is connected with the UPS through the first switch and connected with the AC bus through the second switch. In this system structure, the first photovoltaic power generation system can supply power to the UPS through the first switch, or supply power to the AC bus through the second switch. At the same time, the AC bus is also connected with the UPS through the first switch, and when the AC bus is powered on, it can be used to supply power to the UPS. After the UPS is powered on, it is activated to work. The UPS usually also configures a battery, and when the external power supply to the UPS is unstable, the UPS can still output stable 220V AC power to the outside. In this way, under the power supply of the UPS, the other monitoring and control units of the microgrid can work normally.

[0036] Further, in a possible embodiment, the first switch includes a first contact KA1 and a second contact KA2. Referring to Figure 2The first photovoltaic power generation system is connected to the UPS via the second contact KA2, and the AC bus is connected to the UPS via the first contact KA1. When the AC bus is de-energized, the first contact KA1 opens and the second contact KA2 closes, allowing the first photovoltaic power generation system to supply power to the UPS. When the AC bus is energized, the first contact KA1 closes and the second contact KA2 closes, allowing the AC bus to supply power to the UPS. In this embodiment, the first switch can be a regular rotary switch, where the opening and closing of the first contact KA1 and the second contact KA2 can be achieved manually, or it can be a relay, where the opening and closing of the first contact KA1 and the second contact KA2 is achieved by the coil (not shown in the figure) of the relay being charged and attracted. Of course, those skilled in the art can also achieve the opening and closing of the first contact KA1 and the second contact KA2 using other switching devices with similar functions. This embodiment does not impose specific limitations on the selection of the first switch. After the UPS has a power source, it can supply power to other possible devices in the microgrid, such as monitoring and management units. Therefore, the first photovoltaic power generation system has two paths to supply power to the UPS. Path one is through the AC bus of the second switch, allowing the AC bus to supply power to the UPS via the first contact KA1. Path two is directly through the second contact KA2. It should be noted that the prerequisite for the first photovoltaic power generation system to supply power directly or indirectly to the UPS is that the available power generation capacity of the first photovoltaic power generation system is greater than or equal to the first photovoltaic power supply threshold. In one possible embodiment provided in this application, the first photovoltaic inverter in the first photovoltaic power generation system can automatically detect the voltage at the PV (Photovoltaic) input terminal. When the voltage at the PV input terminal reaches a certain value, it can be considered that the available power generation capacity provided by the first photovoltaic power generation system has reached a level greater than or equal to the first photovoltaic power supply threshold. The first photovoltaic inverter will automatically start operation, converting the DC power at the PV input terminal into AC power for external output. The value of the first photovoltaic power supply threshold can be set according to the UPS's external power supply requirements; this embodiment does not impose specific limitations.

[0037] Specifically, the first photovoltaic power generation system supplies power to the UPS through the path one or the path two, depending on the on-off state of the second switch. For example, if the second switch is in the open state, when the first photovoltaic power generation system reaches the power supply condition, i.e., the available power generation power of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the UPS through the second contact KA2; if the second switch is in the closed state, when the first photovoltaic power generation system reaches the power supply condition, i.e., the available power generation power of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the AC bus through the second switch, and the AC bus supplies power to the UPS through the first contact KA1. Alternatively, in the selection of the switch device, the second switch can be set as a normally open switch. In the case that there is no system controller or external force to close the second switch when the micro-grid is in the power-off state, the second switch is in the open state. At this time, when the first photovoltaic power generation system reaches the power supply condition, i.e., the available power generation power of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the UPS through the second contact KA2. Similarly, if the second switch is set as a normally closed switch, in the case that there is no system controller or external force to open the second switch, the second switch is in the closed state. At this time, when the first photovoltaic power generation system reaches the power supply condition, i.e., the available power generation power of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the AC bus through the second switch, and the AC bus supplies power to the UPS through the first contact KA1. Of course, the skilled in the art can also set the opening or closing of the second switch through other switch devices with similar functions, and the selection of the second switch is not specifically limited in the embodiments of the present application.

[0038] After solving the problem of power supply of the UPS before the self-starting of the micro-grid system, another micro-grid system provided by the embodiments of the present application further comprises at least one second photovoltaic power generation system and a system controller. As shown in FIG. 2, the second photovoltaic power generation system is connected to the AC bus through the second switch, and the system controller is connected to the AC bus through the third contact KA3. Figure 3As shown, the UPS is connected with the system controller, for supplying power to the system controller, the second photovoltaic power system includes a second photovoltaic power unit and a second photovoltaic inverter, for supplying power to the AC bus, of course, the second photovoltaic power system can also have multiple second photovoltaic power units and multiple second photovoltaic inverters, the embodiments of the present application do not make specific limitations. The system controller is in communication connection with the first photovoltaic power system, the second photovoltaic power system and the second switch, can control the opening or closing of the second switch, and is used for controlling the first photovoltaic power system and / or the second photovoltaic power system to supply power to the AC bus. Specifically, when the second switch is a normally open switch, if it is needed to control the first photovoltaic system and the second photovoltaic system to supply power to the AC bus together, the system controller can first control the second switch to be closed, and then control the first photovoltaic power system and the second photovoltaic power system to supply power to the AC bus together; when the second switch is a normally closed switch, the first photovoltaic power system can have a self-starting function, the first photovoltaic power system is in a conductive state between the first photovoltaic power system and the AC bus, the first photovoltaic power system can automatically supply power to the AC bus directly or indirectly when the self-starting condition is reached, the system controller can continue to control the second photovoltaic power system to supply power to the AC bus, to realize the first photovoltaic power system and the second photovoltaic power system to supply power to the AC bus.

[0039] It should be understood that one of the basic functions of the second switch is to quickly open when a fault occurs in the circuit at either end of the second switch, so as to protect the other way from being affected, therefore, in actual application, all photovoltaic power systems can be configured with a second switch, and the embodiments of the present application are only exemplarily described the influence of the second switch corresponding to the first photovoltaic power system on the self-starting of the micro-grid system for the convenience of discussion.

[0040] In a possible implementation manner, continuing to refer to Figure 3 The micro-grid system can further include at least one energy storage power supply system. The introduction of the energy storage power supply system can improve the stability of power supply, and when the storage capacity is large enough, the photovoltaic power system can maintain continuous power supply to the micro-grid under the condition that the photovoltaic power system does not have power generation conditions (such as at night). The energy storage power supply system can have one or more energy storage units and one or more energy storage converters. The energy storage unit is used for storing power, and can adopt a lithium iron phosphate battery or a lead-acid battery, and the embodiments of the present application do not make specific limitations on the specific type of the battery. The energy storage converter can convert the direct current output by the energy storage unit into alternating current and output to the AC bus, to realize the power supply of the energy storage power supply system to the AC bus, and can also convert the alternating current input by the AC bus into direct current and input to the energy storage unit, to realize the charging of the AC bus to the energy storage power supply system.

[0041] It should be noted that the precondition for the energy storage power supply system to charge or discharge is that the energy storage power supply system should be in a running state, and a certain power consumption will be generated in the running process. Before charging and discharging, the system controller needs to control the AC bus to supply power to the energy storage power supply system, so as to wake up the energy storage power supply system and make it start to enter the running state.

[0042] It should be understood that the precondition for the system controller to control the AC bus to supply power to the energy storage power supply system is that the available power generation of the first photovoltaic power generation system and the second photovoltaic power generation system needs to be greater than the power consumption of the energy storage power supply system itself in running, otherwise the microgrid as a whole will be in a power loss state after the energy storage power supply system is woken up. Therefore, in actual application, a second photovoltaic power supply threshold can be set, and when the sum of the available power generation of the first photovoltaic power generation system and the second photovoltaic power generation system is greater than the second photovoltaic power supply threshold, the first photovoltaic power generation system and / or the second photovoltaic power generation system can be controlled to supply power to the AC bus, and the AC bus supplies power to the energy storage power supply system, so that the energy storage power supply system starts to enter the running state and realizes the wake-up of the energy storage power supply system.

[0043] It should be understood that since the available power generation of the photovoltaic power generation system often changes due to changes in the weather environment, the available power generation output can be unstable. In order to improve power supply, the energy storage power supply system can be used as a power supply source of the microgrid, so that the load running by using the microgrid power supply is more stable and safer. Of course, the precondition for using the energy storage power supply system for power supply is that the energy storage power supply system itself has a certain amount of storage power. In a possible implementation manner, an energy storage power supply threshold can be set for the energy storage power supply system. When the energy storage power supply system is in a running state, if the storage power of the energy storage power supply system is greater than or equal to the energy storage power supply threshold, the system controller can control the energy storage power supply system to supply power to the AC bus; if the storage power of the energy storage power supply system is less than the energy storage power supply threshold, the AC bus can be controlled to charge the energy storage power supply system. When there are multiple energy storage power supply systems, such control is more flexible. The energy storage power supply system with high storage power can stably supply power to the AC bus, and the energy storage power supply system with less remaining storage power can be charged by the AC bus to improve the storage power.

[0044] The above merely provides a specific implementation manner of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A microgrid system, characterized in that: include: First photovoltaic power generation system, AC bus, uninterruptible power supply UPS, system controller, first switch and second switch; The first photovoltaic power generation system includes at least one first photovoltaic power generation unit and at least one first photovoltaic inverter, which is connected to the UPS through the first switch and to the AC bus through the second switch, for supplying power to the UPS through the first switch or to the AC bus through the second switch; The AC bus is connected to the UPS via the first switch and is used to supply power to the UPS when it is powered on. The first switch includes a first contact KA1 and a second contact KA2; The photovoltaic power generation system is connected to the UPS via the second contact KA2; The AC busbar is connected to the UPS via the first contact KA1; The first contact KA1 is used to open when the AC bus is de-energized and close when the AC bus is energized. The second contact KA2 is used to close when the AC bus is de-energized and to open when the AC bus is energized. The first photovoltaic power generation system supplies power to the UPS through the second contact KA2; When the AC bus is energized, the first contact KA1 is turned on and the second contact KA2 is turned off, and the AC bus supplies power to the UPS through the first contact KA1; The UPS is connected to the system controller and is used to supply power to the system controller; When the microgrid experiences a power outage, the system controller is activated when the available power output of the first photovoltaic power generation system is greater than or equal to the first photovoltaic power supply threshold. The system controller is used to restore the AC bus voltage and restart the microgrid system when the power generation of the photovoltaic power generation system reaches a predetermined threshold.

2. The microgrid system according to claim 1, characterized in that: When the available power output of the first photovoltaic power generation system is greater than or equal to the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the AC bus through the second switch, so that the AC bus supplies power to the UPS through the first contact KA1; or When the available power output of the first photovoltaic power generation system is greater than or equal to the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the UPS through the second contact KA2.

3. The microgrid system according to claim 1, characterized in that: If the second switch is in the open state, when the available power of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the UPS through the second contact KA2.

4. The microgrid system according to claim 1, characterized in that: If the second switch is closed, when the available power of the first photovoltaic power generation system is greater than the first photovoltaic power supply threshold, the first photovoltaic power generation system supplies power to the AC bus through the second switch, so that the AC bus supplies power to the UPS through the first contact KA1.

5. The microgrid system according to any one of claims 1-4, characterized in that: When a fault occurs in the AC bus side circuit, the first contact KA1 of the first switch opens and the second contact KA2 closes, and the first photovoltaic power generation unit supplies power to the UPS through the second contact KA2 of the first switch.

Images