Micro-grid system

Abstract

The utility model belongs to the technical field of micro-grids, and particularly relates to a micro-grid system, which comprises power generation equipment, energy storage equipment and a direct-current bus, the input side of the direct-current bus is connected with the power generation equipment and the energy storage equipment, the output side of the direct-current bus is connected to a step-down transformer through a second one-way DC / DC converter, and the step-down transformer is connected with two groups of parallel low-voltage storage battery packs. One of the two low-voltage storage battery packs is used and the other is standby; the first low-voltage storage battery pack comprises a low-voltage storage battery I and a switch V which are electrically connected in sequence; the second low-voltage storage battery pack comprises a second low-voltage storage battery, a sixth switch and a fifth switch, the sixth switch is connected to the low-voltage power distribution unit, and the low-voltage power distribution unit is electrically connected with all power electronic equipment in the micro-grid system. According to the utility model, through the configuration of the low-voltage storage battery pack with one used storage battery and one standby storage battery, the continuous operation of power electronic equipment is ensured, and the reliability of the whole micro-grid system is ensured.

Description

TECHNICAL FIELD

[0001] The utility model belongs to microgrid technical field, concretely relates to a microgrid system. BACKGROUND

[0002] The microgrid system is a small type power supply system which is composed of distributed power supply, energy storage device, energy conversion device, load and the like. The microgrid is proposed to realize flexible and efficient application of the distributed power supply and solve the grid connection problem of the large number of various distributed power supplies. The development and extension of the microgrid can fully promote the large-scale access of the distributed power supply and renewable energy, realize the high reliable supply of various energy forms of load and is an effective way to realize the active distribution network, which makes the traditional power grid transit to the smart grid.

[0003] However, the reliability of the existing microgrid system still needs to be improved, the microgrid system is unstable, which can easily cause power grid failure, unstable load power supply, power quality decline and many other problems, and affects the power safety. UTILITY MODEL CONTENT

[0004] The utility model solves the problem of how to improve the reliability of the microgrid system.

[0005] In order to solve the above technical problem, the utility model provides the following technical scheme:

[0006] The utility model discloses a microgrid system, including power generation equipment and energy storage equipment, still including DC bus, DC bus input side is connected with power generation equipment, energy storage equipment, DC bus output side is connected to voltage reducer through second unidirectional DC / DC converter, voltage reducer connects two groups of parallel low voltage battery group, two groups of low voltage battery group are used as one and one spare;The first group of low voltage battery group includes low voltage battery one, switch five that are electrically connected in sequence;The second group of low voltage battery group includes low voltage battery two, switch six, switch five, switch six are connected to low voltage power distribution unit respectively, and the low voltage power distribution unit is electrically connected with all power electronic equipment in the microgrid system.

[0007] Further, the power generation equipment includes the photovoltaic generator set connected with the DC bus, and the photovoltaic generator set includes photovoltaic array and first unidirectional DC / DC converter, switch one that are electrically connected in sequence, and the switch one is electrically connected to the DC bus.

[0008] Further, the power generation equipment further includes the wind driven generator set connected with the DC bus, and the wind driven generator set includes wind driven generator and AC / DC converter, switch two that are electrically connected in sequence, and the switch two is electrically connected to the DC bus.

[0009] Further, the energy storage device comprises two battery banks, each of which is connected to the DC bus through a bidirectional DC / DC converter and a switch.

[0010] Further, the first battery bank comprises a first battery, a first bidirectional DC / DC converter and a switch three connected in sequence, and the switch three is electrically connected to the DC bus.

[0011] Further, the second battery bank comprises a second battery, a second bidirectional DC / DC converter and a switch four connected in sequence, and the switch four is electrically connected to the DC bus.

[0012] Further, the second battery is connected with a UPS, the UPS is connected to the DC bus, and the UPS is also externally connected to the commercial power.

[0013] Further, an inverter and an AC bus are further included, the output side of the DC bus is connected to the inverter and then connected to the AC bus, and the AC bus is connected with a plurality of AC loads.

[0014] Further, the second unidirectional DC / DC converter is also connected with a DC load.

[0015] Further, the power electronic device comprises a first unidirectional DC / DC converter, an AC / DC converter, a first bidirectional DC / DC converter, a second bidirectional DC / DC converter, a second unidirectional DC / DC converter, a voltage reducer and an inverter.

[0016] Compared with the prior art, the utility model has the advantages of:

[0017] The second unidirectional DC / DC converter is connected with a voltage reducer, the voltage reducer is connected with two groups of parallel low-voltage battery banks, one of the two groups of low-voltage battery banks is used and the other is reserved, the two groups of low-voltage battery banks work in the mode of "one used and one reserved", under normal circumstances, one group of low-voltage battery banks (for example, the first group) is in working state, and the other group (for example, the second group) is in standby state, when the low-voltage battery bank in working state is insufficient in power or fails, the switching and starting of the standby low-voltage battery bank can be realized by controlling the closing and opening of the switch five and the switch six. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The utility model discloses a microgrid system's structure schematic view.

[0019] Reference signs:

[0020] 10 is photovoltaic array, 11 is first unidirectional DC / DC converter, 12 is switch one, 20 is wind driven generator, 21 is AC / DC converter, 22 is switch two, 30 is first battery, 31 is first bidirectional DC / DC converter, 32 is switch three, 33 is second battery, 34 is second bidirectional DC / DC converter, 35 is switch four, 40 is second unidirectional DC / DC converter, 50 is voltage reducer, 60 is low voltage battery one, 61 is switch five, 62 is low voltage battery two, 63 is switch six, 70 is low voltage distribution unit, 80 is inverter, 90 is monitoring module, 91 is central control module.

[0021] 30 is first battery, 31 is first bidirectional DC / DC converter, 32 is switch three, 33 is second battery, 34 is second bidirectional DC / DC converter, 35 is switch four, 40 is second unidirectional DC / DC converter, 50 is voltage reducer, 60 is low voltage battery one, 61 is switch five, 62 is low voltage battery two, 63 is switch six, 70 is low voltage distribution unit, 80 is inverter, 90 is monitoring module, 91 is central control module.

[0022] 40 is second unidirectional DC / DC converter, 50 is voltage reducer, 60 is low voltage battery one, 61 is switch five, 62 is low voltage battery two, 63 is switch six, 70 is low voltage distribution unit, 80 is inverter, 90 is monitoring module, 91 is central control module. Specific implementation

[0023] The technical scheme of the utility model will be described clearly below in combination with the drawings, obviously, the described embodiment is not all the embodiments of the utility model, all other embodiments obtained by the ordinary skilled in the art without making creative efforts belong to the protection scope of the utility model.

[0024] As Figure 1 The utility model discloses a microgrid system, the microgrid system includes power generation equipment and energy storage equipment, DC bus, AC bus and load part, DC bus is connected with power generation equipment, energy storage equipment and load part, in the system, DC bus receives the electric energy from power generation equipment, and these electric energy is transmitted to energy storage equipment and load part through power electronic equipment (such as DC / DC converter, inverter etc.

[0025] Power generation equipment includes wind driven generator set and photovoltaic generator set connected with DC bus, photovoltaic generator set includes photovoltaic array 10 and first unidirectional DC / DC converter 11 that electric connection in proper order, switch one 12, switch one 12 is electrically connected to DC bus, and first unidirectional DC / DC converter 11 changes the direct current electric energy generated by photovoltaic array 10, and then converges to DC bus through switch one 12.

[0026] Wind driven generator set includes wind driven generator 20 and AC / DC converter 21 that electric connection in proper order, switch two 22, switch two 22 is electrically connected to DC bus, and AC / DC converter 21 converts the alternating current electric energy generated by wind driven generator 20 into direct current, and then converges to DC bus through switch two 22.

[0027] The energy storage device includes two battery banks, each of which is connected to the DC bus through a bidirectional DC / DC converter and a switch. The energy storage device can provide power buffering between the power generation device and the load.

[0028] The first battery bank includes a first battery 30, a first bidirectional DC / DC converter 31, and a switch three 32 connected in sequence, and the switch three 32 is electrically connected to the DC bus; the first battery 30 takes or supplies power to the DC bus through the first bidirectional DC / DC converter 31 and the switch three 32. The first bidirectional DC / DC converter 31 converts and matches the DC power of the first battery 30 with the power on the DC bus. When the first battery 30 needs to be charged, it can receive power from the DC bus; when the first battery 30 needs to be discharged, it can transmit power to the DC bus.

[0029] The switch three 32 controls the power transmission between the first battery bank and the DC bus. When the switch three 32 is closed, the first battery bank can exchange power with the DC bus; when the switch three 32 is opened, the electrical connection between the first battery bank and the DC bus is cut off.

[0030] The second battery bank includes a second battery 33, a second bidirectional DC / DC converter 34, and a switch four 35 connected in sequence, and the switch four 35 is electrically connected to the DC bus; the second battery 33 takes or supplies power to the DC bus through the second bidirectional DC / DC converter 34 and the switch four 35. The function of the second bidirectional DC / DC converter 34 is the same as that of the first bidirectional DC / DC converter 31, which is responsible for converting and matching the DC power of the second battery 33 with the power on the DC bus. The function of the switch four 35 is similar to that of the switch three 32, which controls the power transmission between the second battery bank and the DC bus.

[0031] The output side of the DC bus is connected to the DC load through the second unidirectional DC / DC converter 40, which supplies power to the DC load, which can be a charging pile. The second unidirectional DC / DC converter 40 converts the power on the DC bus into power suitable for use by the DC load. Through the conversion and adjustment of the second unidirectional DC / DC converter 40, the power on the DC bus can be efficiently transmitted to the DC load, reducing the waste and loss of power. The unidirectional DC / DC converter ensures unidirectional transmission of power, avoids unstable factors in the system, and improves the stability and safety of the system.

[0032] The second unidirectional DC / DC converter 40 is also connected to a voltage reducer 50, which is connected to two groups of low-voltage battery banks in parallel, with one group in use and the other group in standby. The first group of low-voltage battery banks includes a low-voltage battery 1 60 and a switch 5 61 connected in sequence, and the second group of low-voltage battery banks includes a low-voltage battery 2 62 and a switch 6 63. The two groups of low-voltage battery banks work in a "one in use and one in standby" mode, ensuring the reliability and stability of the system.

[0033] When it is necessary to charge the low-voltage battery banks, the second unidirectional DC / DC converter 40 converts high-voltage direct current power into low-voltage direct current power. After the voltage is further reduced by the voltage reducer 50, the power is transmitted to the low-voltage battery 1 60 or the low-voltage battery 2 62 for charging.

[0034] Under normal circumstances, one group of low-voltage battery banks (e.g., the first group) is in working state, and the other group (e.g., the second group) is in standby state. When the working low-voltage battery bank is insufficient in power or fails, the switching and starting of the standby low-voltage battery bank can be realized by controlling the closing and opening of the switch 5 61 and the switch 6 63.

[0035] The "one in use and one in standby" configuration of the low-voltage battery banks ensures reliable power supply of the system under any circumstances. The use of the second unidirectional DC / DC converter 40 and the voltage reducer 50 improves the transmission efficiency and utilization rate of power. The system realizes efficient conversion, storage, and distribution of power through the configuration of the second unidirectional DC / DC converter 40, the voltage reducer 50, and the two groups of low-voltage battery banks in parallel (one in use and one in standby), providing strong support for the stable operation of the micro-grid system and efficient energy management.

[0036] The switch 5 61 and the switch 6 63 are connected to a low-voltage power distribution unit 70, which obtains power from either of the two groups of low-voltage battery banks. The low-voltage power distribution unit 70 is electrically connected to all power electronic devices in the micro-grid system, including the first unidirectional DC / DC converter 11, the AC / DC converter 21, the first bidirectional DC / DC converter 31, the second bidirectional DC / DC converter 34, the second unidirectional DC / DC converter 40, the voltage reducer 50, and the inverter 80. The low-voltage power distribution unit 70 provides working voltage for each power electronic device, ensuring the reliability of the operation of the power electronic devices.

[0037] The voltage reducer 50 further reduces the DC voltage output by the second unidirectional DC / DC converter 40 to a voltage level suitable for charging the low-voltage battery bank, and provides a charging voltage for the low-voltage battery bank. The low-voltage battery bank stores electrical energy, one set of battery bank is in use, and the other set is in standby, and provides electrical energy for the low-voltage distribution unit 70, ensuring the continuous power supply capability of the entire system. The low-voltage distribution unit 70 obtains electrical energy from either of the two sets of low-voltage battery banks and distributes it to each power electronic device in the micro-grid system. Through the "one-use-one-backup" configuration of the low-voltage battery bank and the low-voltage distribution unit, the system can maintain reliable power supply under any circumstances. Even in the event of a malfunction or insufficient power in one set of battery bank, the low-voltage distribution unit can quickly switch to the other set of battery bank, ensuring the continuous operation of the power electronic device.

[0038] The second battery 33 is connected to a UPS, the UPS is connected to the DC bus, and the UPS is also externally connected to the mains, so that the UPS can not only obtain power from the second battery 33, but also obtain power from the mains, and the UPS is connected to each device in the micro-grid system to provide emergency operating voltage for each device. The mains is the main power source of the UPS, and the second battery 33 is the backup power source of the UPS, which provides electrical energy when the mains fails. When the mains is normal, the UPS converts the mains into electrical energy suitable for use in the micro-grid system; when the mains fails, the UPS obtains power from the second battery 33 set to continue to supply power to the device. The UPS can also obtain power from the DC bus, ensuring the reliability of the system operation.

[0039] The output side of the DC bus is connected to the inverter 80 and then connected to the AC bus, and the AC bus is connected to a plurality of AC loads, such as AC load one and AC load two, which can be lighting devices, motors, etc. The DC bus transmits DC electrical energy to the inverter 80, the inverter 80 converts the DC electrical energy into AC electrical energy and outputs it to the AC bus, and the AC bus distributes the AC electrical energy output by the inverter 80 to a plurality of AC loads, and each AC load obtains electrical energy from the AC bus according to its own needs.

[0040] The micro-grid system further comprises a monitoring module 90 and a central control module 91 connected to the monitoring module 90, and the monitoring module 90 is signal-connected to the electrical equipment in the micro-grid system for monitoring the operating state of the electrical equipment, including but not limited to operating voltage, power, current and other key parameters. The monitoring module 90 can adopt any device in the prior art that can monitor the operating state of the device. The monitoring module 90 collects the operating data of the device in real time, such as voltage, current, power, frequency, etc., and uploads these data to the central control module 91 for processing and analysis.

[0041] The central control module 91 is in communication connection with the electrical equipment in the micro-grid system (the specific communication connection line is not shown in the figure, and the signal line is consistent with that of the monitoring module 90), according to the monitoring result of the monitoring module 90, the central control module 91 can control the running state of the electrical equipment in the micro-grid system, for example, when the monitoring module 90 monitors that the low-voltage storage battery 1 60 is insufficient, the central control module 91 controls the switch five 61 to be disconnected and the switch six 63 to be closed, and switches to the low-voltage storage battery 2 62 to supply power to the low-voltage power distribution unit 70. According to the power of the DC load and the AC load, the central control module 91 can also control the opening and closing of the switch one 12 to the switch four 35, change the number of power generation equipment and energy storage equipment, and adjust the power generation and energy storage strategy of the power generation equipment and the energy storage equipment.

[0042] Finally, it should be noted that the above is only used to illustrate the technical scheme of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical scheme of the present application by those skilled in the art do not deviate from the essence and scope of the technical scheme of the present application.

Claims

1. A microgrid system comprising a power generation device and an energy storage device, characterized by, The direct current bus is connected with the power generation device and the energy storage device at the input side, and connected with the voltage reducer at the output side through the second unidirectional DC / DC converter, the voltage reducer is connected with two groups of parallel low-voltage storage batteries, and the two groups of low-voltage storage batteries are used alternately; the first group of low-voltage storage batteries comprises a low-voltage storage battery one and a switch five which are electrically connected in sequence; the second group of low-voltage storage batteries comprises a low-voltage storage battery two and a switch six, and the switch five and the switch six are connected to the low-voltage power distribution unit, and the low-voltage power distribution unit is electrically connected with all power electronic devices in the micro-grid system.

2. The microgrid system of claim 1, wherein, The power generation device comprises a photovoltaic generator set connected with the direct current bus, and the photovoltaic generator set comprises a photovoltaic array and a first unidirectional DC / DC converter which are electrically connected in sequence, and a switch one, and the switch one is electrically connected to the direct current bus.

3. The microgrid system of claim 2, wherein, The power generation device further comprises a wind power generator set connected with the direct current bus, and the wind power generator set comprises a wind power generator and an AC / DC converter which are electrically connected in sequence, and a switch two, and the switch two is electrically connected to the direct current bus.

4. The microgrid system of claim 3, wherein, The energy storage device comprises two storage battery groups, each of which is connected with the direct current bus through a bidirectional DC / DC converter and a switch, and the two storage battery groups are a first storage battery group and a second storage battery group.

5. The microgrid system of claim 4, wherein, The first storage battery group comprises a first storage battery, a first bidirectional DC / DC converter and a switch three which are electrically connected in sequence, and the switch three is electrically connected to the direct current bus.

6. The microgrid system of claim 5, wherein, The second storage battery group comprises a second storage battery, a second bidirectional DC / DC converter and a switch four which are electrically connected in sequence, and the switch four is electrically connected to the direct current bus.

7. The microgrid system of claim 6, wherein, The second storage battery is connected with a UPS, the UPS is connected to the direct current bus, and the UPS is further connected with commercial power.

8. The microgrid system of claim 7, wherein, The inverter and the alternating current bus are further included, the output side of the direct current bus is connected to the inverter and then connected to the alternating current bus, and the alternating current bus is connected with a plurality of alternating current loads.

9. The microgrid system of claim 8, wherein, The second unidirectional DC / DC converter is further connected with a direct current load.

10. The microgrid system of claim 9, wherein, The power electronic device comprises the first unidirectional DC / DC converter, the AC / DC converter, the first bidirectional DC / DC converter, the second bidirectional DC / DC converter, the second unidirectional DC / DC converter, the voltage reducer and the inverter.

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