Black start system, micro-grid and black start method of micro-grid

Abstract

A black start system disclosed by the present invention comprises a first black start power supply, a black start power supply switch and a control system, the black start power supply switch supplies energy to the control system after being triggered by the first black start power supply, and the first black start power supply supplies energy through an energy storage battery; the invention discloses a micro-grid which comprises a power generation system and the black-start system, the invention also discloses a black-start method applied to the micro-grid, the black-start power supply triggers the black-start power supply switch and then supplies energy to the control system, and the power generation system is gradually started to the whole micro-grid. According to the invention, the energy storage battery is used as energy for black start, the characteristic that the energy storage battery performs electric quantity early warning to keep the lowest electric quantity and low electric quantity from the power grid for charging is utilized, stable and continuous energy can be provided for black start, and meanwhile, the situation that the energy storage battery is damaged due to the fact that the electric quantity of the energy storage battery is exhausted is avoided.

Description

Technical Field

[0001] The present invention relates to the field of microgrids, and in particular to a black start technology of microgrids. Background Art

[0002] With the development of distributed power generation technology, power electronics technology and energy storage technology, a variety of power generation devices and energy storage devices are combined through power electronics technology to form an independent power supply system, which provides power support for remote areas or island load equipment in the form of microgrids.

[0003] The microgrid system does not rely on the large power grid to operate independently. When it is first started, the power supply needs to be started to start the microgrid system and provide stable power to the external load. Therefore, the microgrid system needs to have an isolated grid black start function.

[0004] The black start of a microgrid refers to the entire microgrid system being shut down due to a fault, with the entire system being completely blacked out. In this state, the system is gradually started up using only the energy with black start capability in the system itself, without the help of the large power grid or other external power, and then drives the energy without black start capability in the microgrid, ultimately achieving full startup of the microgrid system.

[0005] However, most current projects are based on a single UPS (Uninterruptible Power Supply) or a black start of energy components such as photovoltaic power generation components, hydropower generation components, and wind power generation components to start the microgrid system. However, the use of a single UPS black start may result in the UPS battery pack being depleted due to long downtime, and when using energy components for black start, the energy components may experience large fluctuations in power generation current due to weather factors such as current sunshine, cloud cover, water potential, and wind, which may cause the black start power supply of the energy components to be frequently damaged, reducing the stability of the microgrid black start. Summary of the invention

[0006] In order to overcome the problems existing in the related art, the present invention provides a black start system, including a first black start power supply, a black start power switch and a control system, wherein the black start power switch supplies energy to the control system after being triggered by the first black start power supply; the control system includes a DC converter control module, an energy storage battery control module and an energy storage inverter control module; the DC converter control module, the energy storage battery control module and the energy storage inverter control module are respectively connected in parallel with the black start power switch; the DC converter control module controls the operation of the DC converter, the energy storage battery control module controls the operation of the energy storage battery, and the energy storage inverter control module controls the operation of the energy storage inverter; the first black start power supply is powered by the energy storage battery.

[0007] Furthermore, a first circuit breaker is provided between the black start power switch and the DC converter control module; a second circuit breaker is provided between the black start power switch and the energy storage battery control module; and a third circuit breaker is provided between the black start power switch and the energy storage converter control module.

[0008] Furthermore, it also includes a second black start power supply, and the second black start power supply is powered by a UPS.

[0009] The present invention provides a microgrid, including a power generation system and a black start system, wherein the power generation system includes a DC side and an AC side; the DC side includes an energy component, a DC converter, an energy storage battery and a DC bus, and the AC side includes an AC bus and a UPS; an energy storage converter is used between the DC side and the AC side to convert DC power into AC power;

[0010] Furthermore, the black start system also includes a second black start power supply, and the second black start power supply is powered by a UPS.

[0011] Furthermore, a fourth circuit breaker is provided between the energy storage battery and the first black start power supply, the first black start power supply is powered by the energy storage battery, a fifth circuit breaker is provided between the UPS and the second black start power supply, a sixth circuit breaker is provided between the energy component and the DC converter, and a seventh circuit breaker is provided between the energy storage battery and the DC bus.

[0012] The present invention provides a black start method for a microgrid. When the microgrid is in black start, an energy storage battery supplies energy to a first black start power supply, triggering a black start power switch to supply energy to a control system; a DC converter control module, an energy storage battery control module, and an energy storage inverter control module in the control system are powered on respectively, and the DC converter, the energy storage battery, and the energy storage inverter are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to a DC bus, and the energy storage battery is charged and discharged; the energy storage inverter converts the DC power of the DC bus into AC power and transmits it to the AC bus, and the microgrid completes the black start.

[0013] Furthermore, when the power of the energy storage battery is below a preset value, after the black start power switch is triggered to supply energy to the control system, it further includes: the DC converter control module and the energy storage battery control module in the control system are powered on, and the DC converter and the energy storage battery are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and charges the energy storage battery through the DC bus; when the power of the energy storage battery meets the preset value requirement, the energy storage inverter control module in the control system is powered on, and the energy storage inverter is controlled to convert the DC power of the DC bus into AC power through the energy storage AC converter and transmit it to the AC bus, and the microgrid completes the black start.

[0014] The present invention also provides a black start method for a microgrid. When the microgrid is black started, the energy storage battery supplies energy to a first black start power supply, the UPS supplies energy to a second black start power supply, and the first black start power supply or the second black start power supply triggers a black start power switch to supply energy to the control system; the DC converter control module, the energy storage battery control module, and the energy storage inverter control module in the control system are powered on respectively, and the DC converter, the energy storage battery, and the energy storage inverter are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and the energy storage battery is charged and discharged; the energy storage inverter converts the DC power of the DC bus into AC power and transmits it to the AC bus, and the microgrid completes the black start.

[0015] Furthermore, when the power of the energy storage battery is below a preset value, the first black start power supply or the second black start power supply triggers the black start power switch to supply power to the control system, further comprising: the DC converter control module and the energy storage battery control module in the control system are powered on, and the DC converter and the energy storage battery are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and charges the energy storage battery through the DC bus; when the power of the energy storage battery meets the preset value requirement, the energy storage inverter control module in the control system is powered on, and the energy storage inverter is controlled to convert the DC power of the DC bus into AC power through the energy storage AC converter and transmit it to the AC bus, and the microgrid completes the black start.

[0016] The black start system provided by the embodiment of the present invention uses the energy storage battery as the energy source for black start, and utilizes the characteristic that the energy storage battery will retain the minimum power, so as to provide stable and continuous starting energy for black start, and at the same time, the energy storage battery itself will not be damaged due to exhaustion of power.

[0017] The microgrid and microgrid black start method provided in the embodiments of the present invention use the energy storage battery of the microgrid itself as one of the energy sources for the black start of the microgrid, and can further adopt the dual-path black start function of UPS and energy storage battery, which not only avoids the single UPS black start from exhausting the UPS power and thus damaging the UPS equipment, but also utilizes the characteristics of the energy storage battery to provide power warning to maintain a certain minimum power and charge from the power grid when the power is low, which can always provide stable and continuous starting energy for the black start, and at the same time, the energy storage battery and UPS will not be damaged due to exhaustion of power.

[0018] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings herein are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present invention, and together with the description, are used to explain the principles of the present invention. In the drawings:

[0020] Figure 1 is a block diagram of a black start system structure according to a first embodiment of the present invention;

[0021] Figure 2 is a block diagram of a black start system according to a second embodiment of the present invention;

[0022] Figure 3 is a block diagram of a microgrid structure shown in the third embodiment of the present invention;

[0023] Figure 4 is a block diagram of a microgrid structure shown in the fourth embodiment of the present invention;

[0024] Figure 5 is a first flow chart of a microgrid black start method according to a fifth embodiment of the present invention;

[0025] Figure 6 is a second flow chart of a microgrid black start method according to a fifth embodiment of the present invention;

[0026] Figure 7 is a third flow chart of a microgrid black start method according to a sixth embodiment of the present invention;

[0027] Figure 8 It is a fourth flow chart of the microgrid black start method shown in the sixth embodiment of the present invention.

[0028] The above drawings have shown clear embodiments of the present invention, which will be described in more detail below. These drawings and text descriptions are not intended to limit the scope of the present invention in any way, but to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0029] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of systems and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0030] First embodiment

[0031] The first embodiment of the present invention provides a black start system 2, such as Figure 1 As shown, the black start system 2 in this embodiment includes a first black start power supply 211, a black start power switch 213 and a control system 22. The black start power switch 213 supplies energy to the control system 22 after being triggered by the first black start power supply 211;

[0032] In this embodiment, the control system 22 includes a DC converter control module 221, an energy storage battery control module 222 and an energy storage converter control module 223; the DC converter control module 221, the energy storage battery control module 222 and the energy storage converter control module 223 are respectively connected in parallel at both ends of the black start power switch 213; in this embodiment, the DC converter control module 221 controls the DC converter ( Figure 1 The energy storage battery control module 222 controls the energy storage battery 14 to work, and the energy storage converter control module 223 controls the energy storage converter ( Figure 1 The DC converter, energy storage battery 14 and energy storage converter are devices for power conversion and power storage in the microgrid.

[0033] In this embodiment, the first black start power supply 211 is powered by the energy storage battery 14 . A fourth circuit breaker 34 is provided between the energy storage battery 14 and the first black start power supply. By closing the fourth circuit breaker, the energy storage battery 14 can power the first black start power supply 211 .

[0034] The energy storage battery 14 in this embodiment is a BMS battery pack. The BMS lithium battery pack has SOC (State of Charge) control and can store enough electrical energy to support the startup of the energy storage battery control module 222 and the DC converter control module 221 .

[0035] In this embodiment, a first circuit breaker 31 is provided between the black start power switch 213 and the DC converter control module 221; a second circuit breaker 32 is provided between the black start power switch 213 and the energy storage battery control module 222; and a third circuit breaker 33 is provided between the black start power switch 213 and the energy storage converter control module 223. When the microgrid operates normally, each circuit breaker in the black start system is in an open state and does not need to consume power; and when the microgrid is in black start, each circuit breaker can be controlled to be closed separately to activate the corresponding components in the black start system to perform a black start.

[0036] The first black start power supply 211 in this embodiment can be a DC converter or other devices that can convert the high voltage DC of the energy storage battery 14 into a 24V low voltage DC. The black start power switch 213 in this embodiment can be a unidirectional or bidirectional two-input and one-output power switch, such as ATS (Automatic Transfer Switch).

[0037] The black start system of this embodiment uses the energy storage battery as the energy source for black start, and utilizes the characteristic of the energy storage battery that it will issue a power warning to maintain a certain minimum power level, so as to provide stable and continuous starting energy for black start, and at the same time, the energy storage battery will not be exhausted and damaged.

[0038] Second embodiment

[0039] The second embodiment of the present invention provides a black start system 2, such as Figure 2 As shown, the black start system 2 in this embodiment includes a first black start power supply 211, a second black start power supply 212, a black start power switch 213 and a control system 22. The black start power switch 213 supplies energy to the control system 22 after being triggered by the first black start power supply 211 or the second black start power supply 212;

[0040] In this embodiment, the control system 22 includes a DC converter control module 221, an energy storage battery control module 222 and an energy storage converter control module 223; the DC converter control module 221, the energy storage battery control module 222 and the energy storage converter control module 223 are respectively connected in parallel at both ends of the black start power switch 213; in this embodiment, the DC converter control module 221 controls the DC converter ( Figure 1 The energy storage battery control module 222 controls the energy storage battery 14 to work, and the energy storage converter control module 223 controls the energy storage converter ( Figure 1 The DC converter, energy storage battery 14 and energy storage converter are devices for power conversion and power storage in the microgrid.

[0041] In this embodiment, the first black start power supply 211 is powered by the energy storage battery 14, and the second black start power supply is powered by the UPS 16. A fourth circuit breaker 34 is provided between the energy storage battery 14 and the first black start power supply 211. By closing the fourth circuit breaker 34, the energy storage battery 14 can supply energy to the first black start power supply 211; a fifth circuit breaker 35 is provided between the UPS 16 and the second black start power supply 212. By closing the fifth circuit breaker 35, the UPS 16 can supply energy to the second black start power supply 212.

[0042] In this embodiment, a first circuit breaker 31 is provided between the black start power switch 213 and the DC converter control module 221; a second circuit breaker 32 is provided between the black start power switch 213 and the energy storage battery control module 222; and a third circuit breaker 33 is provided between the black start power switch 213 and the energy storage converter control module 223. When the microgrid operates normally, each circuit breaker in the black start system is in an open state and does not need to consume power; and when the microgrid is in black start, each circuit breaker can be controlled to be closed separately to activate the corresponding components in the black start system to perform a black start.

[0043] The first black start power supply 211 in this embodiment can be a DC converter or other devices that can convert the high-voltage DC of the energy storage battery 14 into a 24V low-voltage DC. The second black start power supply 212 in this embodiment can be a transformer, a step-down converter or other devices that can convert the high-voltage AC of the UPS 16 into a 24V low-voltage AC. The black start power switch 213 in this embodiment is a bidirectional conductive, two-input and one-output power switch, such as ATS (Automatic Transfer Switch).

[0044] The black start system of this embodiment adopts a dual-channel black start function structure of UPS and energy storage battery. The added energy storage battery is used as a redundant design of starting energy. It not only avoids the single UPS black start from exhausting the UPS power and thus damaging the UPS, but also utilizes the characteristic of the energy storage battery to provide power warning and maintain a certain minimum power. It can always provide stable and continuous starting energy for black start, and at the same time, the energy storage battery and UPS will not be damaged due to exhaustion of power.

[0045] Third embodiment

[0046] A third embodiment of the present invention provides a microgrid, such as Figure 3 As shown, it includes a power generation system 1 and the black start system 2 of the first embodiment, and the power generation system 1 includes a DC side and an AC side.

[0047] In this embodiment, the DC side includes an energy component 11, a junction box 12, a DC converter 13, an energy storage battery 14 and a DC bus. Specifically, the energy component 11 in this embodiment is a photovoltaic component or a wind power component, a hydropower component and other new energy components. The microgrid in this embodiment is an independent microgrid that uses photovoltaic components or other new energy components to generate electricity for self-generation and does not rely on external power grids or energy supply.

[0048] In this embodiment, after the energy component 11 generates electric energy, it is directly transmitted to the combiner box 12 for aggregation, and then the sixth circuit breaker 36 is closed to transmit the electric energy to the DC converter 13 to convert it into DC power and then directly transmit it to the DC bus.

[0049] The energy storage battery 14 in this embodiment is a BMS battery pack, and a seventh circuit breaker 37 is provided between the energy storage battery 14 and the DC bus. By closing the seventh circuit breaker 37, the energy storage battery 14 can directly inject its stored electrical energy into the DC bus or obtain electrical energy from the DC bus for charging.

[0050] In this embodiment, the AC side includes an AC bus and a UPS 16; the DC side and the AC side are connected via an energy storage converter 15 to convert DC power into AC power; specifically, the DC bus transmits the DC power on it to the energy storage converter 15 to convert it into AC power for storage, and after the eighth circuit breaker 38 is closed, the AC power is transmitted to the AC bus, the AC bus directly supplies power to the UPS and closes the ninth circuit breaker 39, and the AC bus supplies power to the load 17.

[0051] The black start system in this embodiment is the black start system 2 in the above-mentioned first embodiment. In this embodiment, a fourth circuit breaker 34 is provided between the energy storage battery 14 and the first black start power supply 211. After closing the fourth circuit breaker 34, the energy storage battery 14 can supply energy to the first black start power supply 211.

[0052] The microgrid of this embodiment uses the energy storage battery of the microgrid itself as the energy source for the black start of the microgrid. By utilizing the characteristics of the energy storage battery that can provide power warning and maintain a certain minimum power, it can provide stable and continuous starting energy for the black start of the microgrid, and at the same time, the energy storage battery will not be exhausted and damaged.

[0053] Fourth embodiment

[0054] A fourth embodiment of the present invention provides a microgrid, such as Figure 4 As shown, it includes a power generation system 1 and the black start system 2 of the second embodiment, and the power generation system 1 includes a DC side and an AC side;

[0055] In this embodiment, the DC side includes an energy component 11 and a combiner box 12. The fourth embodiment of the present invention provides a microgrid, such as Figure 4 As shown, a DC converter 13, an energy storage battery 14 and a DC bus. Specifically, the energy component 11 in this embodiment is a photovoltaic component or a wind power component, a hydropower component and other new energy components. The microgrid in this embodiment is an independent microgrid composed of self-generated electricity using photovoltaic components or other new energy components and does not rely on external power grids or energy supply.

[0056] In this embodiment, after the energy component 11 generates electric energy, it is directly transmitted to the combiner box 12 for aggregation, and then the sixth circuit breaker 36 is closed to transmit the electric energy to the DC converter 13 to convert it into DC power and then directly transmit it to the DC bus.

[0057] The energy storage battery 14 in this embodiment is a BMS (Battery Management System) battery pack, and a seventh circuit breaker 37 is arranged between the energy storage battery 14 and the DC bus. By closing the seventh circuit breaker 37, the energy storage battery 14 can directly inject its stored electric energy into the DC bus or obtain electric energy from the DC bus for charging.

[0058] In this embodiment, the AC side includes an AC bus and a UPS 16; the DC side and the AC side are connected via an energy storage converter 15 to convert DC power into AC power; specifically, the DC bus transmits the DC power on it to the energy storage converter 15 to convert it into AC power for storage, and after the eighth circuit breaker 38 is closed, the AC power is transmitted to the AC bus, the AC bus directly supplies power to the UPS and closes the ninth circuit breaker 39, and the AC bus supplies power to the load 17.

[0059] The black start system in this embodiment is the black start system 2 in the second embodiment. The black start system 2 in this embodiment includes a first black start power supply 211, a second black start power supply 212, a black start power switch 213 and a control system 22. The black start power switch 213 supplies energy to the control system 22 after being triggered by the first black start power supply 211 or the second black start power supply 212.

[0060] In this embodiment, the first black start power supply 211 is powered by the energy storage battery 14, and the second black start power supply is powered by UPS16. In this embodiment, the energy storage battery 14 and UPS16 select one of the first black start power supply 211 or the second black start power supply 212 to supply energy for the black start; a fourth circuit breaker 34 is provided between the energy storage battery 14 and the first black start power supply 211, and by closing the fourth circuit breaker 34, the energy storage battery 14 can supply energy to the first black start power supply 211; a fifth circuit breaker 35 is provided between UPS16 and the second black start power supply 212, and by closing the fifth circuit breaker 35, UPS16 can supply energy to the second black start power supply 212.

[0061] The microgrid of this embodiment uses the energy storage battery of the microgrid itself as one of the energy sources for the black start of the microgrid, and adopts a structure in which the black start function is performed alternatively between the UPS and the energy storage battery. The redundant design of the added energy storage battery as the starting energy source not only avoids the single UPS black start from exhausting the UPS power and thus damaging the UPS, but also utilizes the characteristic of the energy storage battery to provide a power warning to maintain a certain minimum power, which can always provide stable and continuous starting energy for the black start, and at the same time, the energy storage battery will not be exhausted and damaged by the energy storage battery itself.

[0062] Fifth embodiment

[0063] The fifth embodiment of the present invention provides a microgrid black start method, which is applied to the microgrid of the third embodiment of the present invention. This embodiment is an implementation method of performing a microgrid black start by using an energy storage battery. The specific implementation steps are as follows: Figure 5 As shown:

[0064] S11: When the microgrid is in black start, the energy storage battery supplies energy to the first black start power supply, triggering the black start power switch to supply energy to the control system;

[0065] Specifically, the black start method of this embodiment is to close the fourth circuit breaker 34, supply energy to the first black start power supply 211 through the energy storage battery 14, and then trigger the black start power switch 213.

[0066] S12: The DC converter control module, the energy storage battery control module, and the energy storage inverter control module in the control system are powered on respectively, and the DC converter, the energy storage battery, and the energy storage inverter are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and the energy storage battery is charged and discharged;

[0067] Specifically, in this embodiment, the first circuit breaker 31 is closed to power on the DC converter control module 221, the second circuit breaker 32 is closed to power on the energy storage battery control module 222, and the third circuit breaker 33 is closed to power on the energy storage inverter control module 223; wherein the powered-on DC converter control module 221 controls the DC converter 13 in the power generation system 1, the powered-on energy storage battery control module 222 controls the energy storage battery 14 in the power generation system 1, and the powered-on energy storage inverter control module 223 controls the energy storage inverter in the power generation system 1.

[0068] Specifically, the present embodiment includes closing the sixth circuit breaker 36, transmitting the generated electric energy produced by the energy component 11 to the DC converter 13 through the combiner box 12, converting it into DC power and then transmitting it to the DC bus; and closing the seventh circuit breaker 37, connecting the energy storage battery 14 and the DC bus. In the present embodiment, after the energy storage battery 14 is connected to the DC bus, the energy storage battery 14 can directly inject electric energy into the DC bus or the DC bus can charge the energy storage battery 14 according to the power status of the energy storage battery.

[0069] S13: The energy storage converter converts the DC power of the DC bus into AC power and transmits it to the AC bus, and the microgrid completes the black start.

[0070] Specifically, in this embodiment, the eighth circuit breaker 38 is closed to convert the DC power of the DC bus into AC power through the energy storage AC device 15 and transmit it to the AC bus, and the microgrid completes the black start.

[0071] In actual situations, the energy storage battery 14 is insufficient in power. When the power of the energy storage battery 14 is above the preset value, the black start method implementation steps are as described above. Figure 5 As shown, when the energy storage battery power is below the preset value, the implementation steps are as follows Figure 6 As shown,

[0072] S111: When the microgrid is in black start, the energy storage battery supplies energy to the first black start power supply, triggering the black start power switch to supply energy to the control system;

[0073] Specifically, the black start method of this embodiment is to close the fourth circuit breaker 34, supply energy to the first black start power supply 211 through the energy storage battery 14, and then trigger the black start power switch 213;

[0074] S121: When the power level of the energy storage battery is below a preset value, after the black start power switch is triggered to supply power to the control system, the process further includes: powering on the DC converter control module and the energy storage battery control module in the control system, respectively controlling the DC converter and the energy storage battery, so that the DC converter transmits the generated power of the energy component to the DC bus, and charges the energy storage battery through the DC bus;

[0075] When the power level of the energy storage battery 14 is below the preset value, the first circuit breaker 31 is closed to power on the DC converter control module 221, and the second circuit breaker 32 is closed to power on the energy storage battery control module 222. The powered-on DC converter control module 221 controls the DC converter 13 in the power generation system 1, and the powered-on energy storage battery control module 222 controls the energy storage battery 14 in the power generation system 1.

[0076] Specifically, in this embodiment, it also includes closing the sixth circuit breaker 36, transmitting the generated electric energy produced by the energy component 11 to the DC converter 13 through the junction box 12, converting it into DC power and then transmitting it to the DC bus; and closing the seventh circuit breaker 37 to connect the energy storage battery 14 and the DC bus. In this embodiment, after the energy storage battery 14 is connected to the DC bus, the DC bus transmits electric energy to the energy storage battery 14 for charging.

[0077] In this embodiment, at this time, the power of the energy storage battery 14 is below the preset value, and the control module of the important device on the DC side of the power generation system 1 is powered on first, and the self-generation of the DC side energy component 11 is started and turned on. The energy storage battery 14 in this embodiment is a BMS battery pack. The BMS lithium battery pack has SOC (State of Charge) control. The preset value in this embodiment is the remaining power ratio represented by SOC, which will store enough power to support the startup of the energy storage battery control module 222 and the DC converter control module 221. When the SOC of the energy storage battery 14, i.e., the BMS battery pack, is too low, the BMS battery pack is pre-charged through the energy component 11, such as the photovoltaic component.

[0078] S131: When the power of the energy storage battery meets the preset value requirement, the energy storage converter control module in the control system is powered on, and the energy storage converter is controlled to convert the DC power of the DC bus into AC power through the energy storage AC converter and transmit it to the AC bus, and the microgrid completes the black start.

[0079] Specifically, in this embodiment, when the power of the energy storage battery 14 meets the preset value requirement, the third circuit breaker 33 is closed to power on the energy storage inverter control module 223, and then the eighth circuit breaker 38 is closed to convert the DC power of the DC bus into AC power through the energy storage AC converter 15 and transmit it to the AC bus, and the microgrid completes the black start.

[0080] The microgrid of this embodiment uses the energy storage battery of the microgrid itself as the energy source for the black start of the microgrid. The energy storage battery will provide a power warning to always maintain a certain minimum power and charge from the grid when the power is low. This can provide a stable and continuous starting energy source for the black start of the microgrid, and at the same time, the energy storage battery will not be exhausted and damaged.

[0081] Sixth embodiment

[0082] The sixth embodiment of the present invention provides a microgrid black start method, which is applied to the microgrid of the fourth embodiment of the present invention. This embodiment is an implementation method for performing a microgrid black start by selecting between an energy storage battery and a UPS. The specific implementation steps are as follows: Figure 7 As shown:

[0083] S21: When the microgrid is in black start, the energy storage battery supplies energy to the first black start power supply, the UPS supplies energy to the second black start power supply, and the first black start power supply or the second black start power supply triggers the black start power switch to supply energy to the control system;

[0084] Specifically, in this embodiment, the energy storage battery 14 supplies energy to the first black start power supply 211, and the UPS 16 supplies energy to the second black start power supply 212. The black start power switch 213 is triggered first by which end of the black start power supply, and the black start is performed by the energy storage battery 14 or UPS 16 corresponding to the currently triggered black start power supply.

[0085] S22: The DC converter control module, the energy storage battery control module, and the energy storage inverter control module in the control system are powered on respectively, and the DC converter, the energy storage battery, and the energy storage inverter are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and the energy storage battery is charged and discharged;

[0086] Specifically, in this embodiment, the first circuit breaker 31 is closed to power on the DC converter control module 221, the second circuit breaker 32 is closed to power on the energy storage battery control module 222, and the third circuit breaker 33 is closed to power on the energy storage inverter control module 223; wherein the powered-on DC converter control module 221 controls the DC converter 13 in the power generation system 1, the powered-on energy storage battery control module 222 controls the energy storage battery 14 in the power generation system 1, and the powered-on energy storage inverter control module 223 controls the energy storage inverter 15 in the power generation system 1.

[0087] Specifically, the steps in this embodiment also include closing the sixth circuit breaker 36, transmitting the generated electric energy produced by the energy component 11 to the DC converter 13 through the junction box 12, converting it into DC power and then transmitting it to the DC bus; and closing the seventh circuit breaker 37, connecting the energy storage battery 14 and the DC bus. In this embodiment, when the energy storage battery 14 performs black start energy supply, after the energy storage battery 14 is connected to the DC bus, the energy storage battery 14 directly injects electric energy into the DC bus; in this embodiment, when the UPS 16 performs black start energy supply, after the energy storage battery 14 is connected to the DC bus, the energy storage battery 14 can directly inject electric energy into the DC bus or the DC bus can charge the energy storage battery 14 according to the power status of the energy storage battery.

[0088] S23: The energy storage converter converts the DC power of the DC bus into AC power and transmits it to the AC bus, and the microgrid completes a black start.

[0089] Specifically, in this embodiment, the eighth circuit breaker 38 is closed to convert the DC power of the DC bus into AC power through the energy storage AC device 15 and transmit it to the AC bus, and the microgrid completes the black start.

[0090] In this embodiment Figure 5 The method flow shown is applicable to black start of UPS 16 or black start when the power of energy storage battery 14 meets the requirement.

[0091] In actual situations, there is a situation where the energy storage battery 14 and / or UPS 16 are insufficient in power. At this time, if UPS 16 does not trigger the black start switch 213, the black start power switch is triggered by the energy storage battery load, and the power of the energy storage battery 14 is below the preset value, then it is necessary to follow Figure 8 Perform a black start by following the steps shown below:

[0092] S211: When the microgrid is in black start, the energy storage battery supplies energy to the first black start power supply, the UPS supplies energy to the second black start power supply, and the first black start power supply or the second black start power supply triggers the black start power switch to supply energy to the control system;

[0093] Specifically, in the present embodiment, when the microgrid is in black start, the fourth circuit breaker 34 and the fifth circuit breaker 35 are closed, the energy storage battery 14 supplies energy to the first black start power supply 211, the UPS 16 supplies energy to the second black start power supply 212, and the first black start power supply 211 or the second black start power supply 212 triggers the black start power switch 213.

[0094] S221: When the power level of the energy storage battery is below a preset value, after the first black start power supply or the second black start power supply triggers the black start power switch to supply power to the control system, the method further includes: powering on the DC converter control module and the energy storage battery control module in the control system, respectively controlling the DC converter and the energy storage battery, so that the DC converter transmits the generated power of the energy component to the DC bus, and charges the energy storage battery through the DC bus;

[0095] Specifically, in this embodiment, the second black start power supply 212 corresponding to the UPS 16 does not trigger the black start power switch 213 and the power of the energy storage battery 14 is below the preset value, and the first circuit breaker 31 is closed to power on the DC converter control module 221, and the second circuit breaker 32 is closed to power on the energy storage battery control module 222; the powered-on DC converter control module 221 controls the DC converter 13 in the power generation system 1, and the powered-on energy storage battery control module 222 controls the energy storage battery 14 in the power generation system 1.

[0096] In this embodiment, it also includes closing the sixth circuit breaker 36 to transmit the generated electric energy produced by the energy component 11 to the DC converter 13 through the junction box 12, converting it into DC power and then transmitting it to the DC bus; and closing the seventh circuit breaker 37 to connect the energy storage battery 14 and the DC bus. In this embodiment, after the energy storage battery 14 is connected to the DC bus, the DC bus transmits electric energy to the energy storage battery 14 for charging.

[0097] In this embodiment, at this time, the power of the energy storage battery 14 is below the preset value, and the control module of the important device on the DC side of the power generation system 1 is powered on first, and the self-generation of the DC side energy component 11 is started and turned on. The energy storage battery 14 in this embodiment is a BMS battery pack. The BMS lithium battery pack has SOC (State of Charge) control. The preset value in this embodiment is the remaining power ratio represented by SOC, which will store enough power to support the startup of the energy storage battery control module 222 and the DC converter control module 221. When the SOC of the energy storage battery 14, i.e., the BMS battery pack, is too low, the BMS battery pack is pre-charged through the energy component 11, such as the photovoltaic component.

[0098] S231: When the power of the energy storage battery meets the preset value requirement, the energy storage converter control module in the control system is powered on, and the energy storage converter is controlled to convert the DC power of the DC bus into AC power through the energy storage AC converter and transmit it to the AC bus, and the microgrid completes the black start.

[0099] Specifically, in this embodiment, when the power of the energy storage battery 14 meets the preset value requirement, the third circuit breaker 33 is closed to power on the energy storage inverter control module 223, and then the eighth circuit breaker 38 is closed to convert the DC power of the DC bus into AC power through the energy storage AC converter 15 and transmit it to the AC bus, and the microgrid completes the black start.

[0100] The microgrid of this embodiment uses the energy storage battery of the microgrid itself as one of the energy sources for the black start of the microgrid, and adopts a structure in which the black start function is performed alternatively between the UPS and the energy storage battery. The redundant design of the added energy storage battery as the starting energy source not only avoids the single UPS black start from exhausting the UPS power and thus damaging the UPS, but also utilizes the characteristics of the energy storage battery to provide power warning to maintain a certain minimum power and charge from the power grid when the power is low, so as to always provide stable and continuous starting energy for the black start, and at the same time, the energy storage battery will not be exhausted and damage the energy storage battery itself.

[0101] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not invented by the present invention. The description and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0102] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A black start system, characterized in that: It comprises a first black start power supply, a black start power switch and a control system, wherein the black start power switch supplies energy to the control system after being triggered by the first black start power supply; The control system includes a DC converter control module, an energy storage battery control module and an energy storage converter control module; the DC converter control module, the energy storage battery control module and the energy storage converter control module are respectively connected in parallel with the black start power switch; The DC converter control module controls the operation of the DC converter, the energy storage battery control module controls the operation of the energy storage battery, and the energy storage converter control module controls the operation of the energy storage converter; The first black start power supply is powered by an energy storage battery.

2. The system according to claim 1, characterized in that: A first circuit breaker is provided between the black start power switch and the DC converter control module; a second circuit breaker is provided between the black start power switch and the energy storage battery control module; and a third circuit breaker is provided between the black start power switch and the energy storage converter control module.

3. The system according to claim 2, characterized in that: Also included is a second black start power supply, which is powered by a UPS.

4. A microgrid, characterized in that: comprising a power generation system and a black start system as claimed in any one of claims 1 to 2, The power generation system includes a DC side and an AC side; The DC side includes energy components, the DC converter, the energy storage battery and a DC bus, and the AC side includes an AC bus and a UPS; the energy storage converter converts DC power into AC power between the DC side and the AC side; The first black start power supply is powered by the energy storage battery.

5. The microgrid according to claim 4, characterized in that: The black start system further includes a second black start power supply, and the second black start power supply is powered by the UPS.

6. The microgrid according to claim 5, characterized in that: A fourth circuit breaker is provided between the energy storage battery and the first black start power supply. A fifth circuit breaker is provided between the UPS and the second black start power supply. A sixth circuit breaker is provided between the energy component and the DC converter. A seventh circuit breaker is provided between the energy storage battery and the DC bus.

7. A black start method for a microgrid, applied to the microgrid according to claim 4, characterized in that: When the microgrid is in black start, the energy storage battery supplies energy to the first black start power supply, triggering the black start power switch to supply energy to the control system; The DC converter control module, the energy storage battery control module, and the energy storage inverter control module in the control system are powered on respectively, and the DC converter, the energy storage battery, and the energy storage inverter are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and the energy storage battery is charged and discharged; The energy storage converter converts the DC power of the DC bus into AC power and transmits it to the AC bus, and the microgrid completes a black start.

8. The method according to claim 7, characterized in that: When the power of the energy storage battery is below a preset value, after the black start power switch is triggered to supply power to the control system, the method further includes: The DC converter control module and the energy storage battery control module in the control system are powered on, and the DC converter and the energy storage battery are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and charges the energy storage battery through the DC bus; When the power of the energy storage battery meets the preset value requirement, the energy storage converter control module in the control system is powered on, and the energy storage converter is controlled to convert the DC power of the DC bus into AC power through the energy storage AC converter and transmit it to the AC bus, and the microgrid completes the black start.

9. A black start method for a microgrid, applied to the microgrid according to claim 5, characterized in that: When the microgrid is in black start, the energy storage battery supplies energy to the first black start power supply, the UPS supplies energy to the second black start power supply, and the first black start power supply or the second black start power supply triggers the black start power switch to supply energy to the control system; The DC converter control module, the energy storage battery control module, and the energy storage inverter control module in the control system are powered on respectively, and the DC converter, the energy storage battery, and the energy storage inverter are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and the energy storage battery is charged and discharged; The energy storage converter converts the DC power of the DC bus into AC power and transmits it to the AC bus, and the microgrid completes a black start.

10. The method according to claim 9, characterized in that: When the power of the energy storage battery is below a preset value, the first black start power supply or the second black start power supply triggers the black start power switch to supply power to the control system, further comprising: The DC converter control module and the energy storage battery control module in the control system are powered on, and the DC converter and the energy storage battery are controlled respectively, so that the DC converter transmits the generated electric energy of the energy component to the DC bus, and charges the energy storage battery through the DC bus; When the power of the energy storage battery meets the preset value requirement, the energy storage converter control module in the control system is powered on, and the energy storage converter is controlled to convert the DC power of the DC bus into AC power through the energy storage AC converter and transmit it to the AC bus, and the microgrid completes the black start.

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