Micro-grid control system and method

Abstract

The invention belongs to the technical field of micro-grids, and particularly relates to a micro-grid control system and method.The micro-grid comprises a centralized power supply system and a plurality of sub-micro-grid systems, the centralized power supply system is distributed energy, each sub-micro-grid system comprises low-voltage energy and loads, and the loads comprise a first-level load and a second-level load; the low-voltage energy source comprises a distributed energy source and an energy storage device, the micro-grid control system comprises a central controller and local controllers arranged corresponding to the sub-micro-grid systems respectively, when the micro-grid is off-grid, the central controller sends the grade of each power load to the local controller of the sub-micro-grid system to which the power load belongs, and the grade of each power load is stored in the central controller. Energy output by the centralized power supply system is distributed to each sub-microgrid system; and the local controller of the sub-micro-grid system controls the sub-micro-grid system to preferentially supply power to the high-grade power load in the sub-micro-grid system so as to realize uninterrupted power supply of the internal important load in the off-grid state of the micro-grid.

Description

Technical Field

[0001] The present invention belongs to the technical field of microgrids, and in particular relates to a microgrid control system and method. Background Art

[0002] A microgrid is a small power generation and distribution system composed of distributed power sources, energy storage devices, energy conversion devices, power loads, monitoring and protection devices, etc. A microgrid can achieve self-sufficiency in a local area, and can even feed back to the large power grid when necessary. There are two common operating modes of a microgrid: one is that when the large power grid is supplying power normally, the distributed energy and energy storage devices in the microgrid are incorporated as auxiliary power sources to jointly supply energy to the power load, which is called the microgrid grid-connected operation mode; the other is that when the large power grid encounters a power outage due to a fault, the microgrid is separated from the large power grid. At this time, the distributed energy and energy storage devices in the microgrid work together to supply energy to the internal power load, which is called the microgrid off-grid operation mode. The energy stored in the distributed energy and energy storage devices in the microgrid is limited. When switching from grid-connected operation to off-grid operation, unreasonable energy distribution will occur, resulting in power outages, which will affect user use. Therefore, a microgrid control system and method are needed to solve the above problems. Summary of the invention

[0003] The purpose of the present invention is to provide a microgrid control system and method, by configuring the energy storage device on the low voltage side, combining the nearby distributed energy and load to form a sub-microgrid system, which is controlled by the local controller in real time on site, giving priority to supplying power to the primary load, avoiding the rough use of energy storage resources. Compared with centralized control, the local controller's on-site real-time control method can improve the response speed of supplying power to the internal power load of the sub-microgrid system, and ensure uninterrupted power supply to the primary load. Moreover, compared with configuring the energy storage device on the medium and high voltage side, configuring the energy storage device on the low voltage side can also reduce the system cost; in addition, using wind and solar power generation to reduce power generation costs and reduce environmental pollution.

[0004] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0005] A microgrid control system, the microgrid comprising a centralized power supply system and a plurality of sub-microgrid systems, the centralized power supply systems are all distributed energy sources, the sub-microgrid systems are composed of low-voltage energy sources and loads, the loads include primary loads, and the low-voltage energy sources include distributed energy sources and energy storage devices;

[0006] The microgrid control system consists of a central controller and several local controllers, wherein the several local controllers are distributed corresponding to each sub-microgrid system, and the central controller stores all power load levels in the microgrid, and is used to distribute the energy in the centralized power supply system to each sub-microgrid system according to each power load level when the microgrid is switched to off-grid operation;

[0007] When the microgrid is operating off-grid, the sub-microgrid system uses the centralized power supply system and the low-voltage energy as energy sources, and several local controllers calculate the power supply energy size and power supply time of the corresponding sub-microgrid system when the microgrid is operating off-grid, and allocate the low-voltage energy in the sub-microgrid system according to the calculation structure to power high-level power loads.

[0008] The sub-microgrid system also includes a mobile energy storage device;

[0009] When the corresponding sub-microgrid system is insufficient to support the power supply of the primary load, the local controller controls the corresponding sub-microgrid system to connect to the corresponding mobile energy storage device.

[0010] The mobile energy storage device includes a charging pile, a generator and a new energy vehicle, and the new energy vehicle supplies reverse power to the sub-microgrid system through the charging pile.

[0011] The microgrid and the plurality of sub-microgrid systems are connected via an optical fiber network.

[0012] A microgrid control method, applied to the microgrid system;

[0013] The central controller and the local controllers monitor the operating status of the microgrid in real time, collect and summarize various operating data, and adjust the operating status of the microgrid at any time.

[0014] The central controller determines that the microgrid is disconnected from the main grid, and the central controller sends information to the plurality of sub-microgrid systems through the optical fiber network, and the plurality of sub-microgrids enter an off-grid operation mode;

[0015] The central controller determines that the microgrid is closed to the main grid, and the central controller sends information to the plurality of sub-microgrid systems through the optical fiber network, and the plurality of sub-microgrids enter a grid-connected operation mode.

[0016] The local controllers in the plurality of sub-microgrids receive control instructions from the central controller to control the sub-microgrids to operate in a grid-connected operation mode or an off-grid operation mode.

[0017] During operation, the local controllers simultaneously collect power consumption and discharge power in the corresponding sub-microgrid, obtain a first critical power value at the power consumption end and a second critical power value at the discharge end, and adjust the discharge power according to the first critical power value and the second critical power value.

[0018] The present invention configures the energy storage device on the low-voltage side, combines the nearby distributed energy and load to form a sub-microgrid system, and controls it on-site in real time by the local controller, giving priority to powering the primary load, avoiding the rough use of energy storage resources. Compared with centralized control, the local controller's on-site real-time control method can improve the response speed of power supply to the power load inside the sub-microgrid system and ensure uninterrupted power supply to the primary load. Moreover, compared with configuring the energy storage device on the medium and high voltage side, configuring the energy storage device on the low voltage side can also reduce system costs; in addition, using wind and solar power generation to reduce power generation costs and reduce environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further illustrated by means of the non-limiting examples given in the accompanying drawings.

[0020] Figure 1 The present invention is a flow chart of a microgrid control method. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0022] A microgrid control system of the present invention, the microgrid includes a centralized power supply system and multiple sub-microgrid systems, the centralized power supply systems are all distributed energy, the sub-microgrid systems are composed of low-voltage energy and loads, the loads include primary loads, and the low-voltage energy includes distributed energy and energy storage devices;

[0023] The microgrid control system consists of a central controller and several local controllers. The local controllers are distributed corresponding to each sub-microgrid system. The central controller stores all the power load levels in the microgrid, which is used to distribute the energy in the centralized power supply system to each sub-microgrid system according to each power load level when the microgrid is switched to off-grid operation.

[0024] When the microgrid is off-grid, the sub-microgrid system uses the centralized power supply system and low-voltage energy as energy sources. Several local controllers calculate the power supply energy and power supply time of the corresponding sub-microgrid system when the microgrid is off-grid, and allocate the low-voltage energy in the sub-microgrid system to supply power to the high-level power load according to the calculation structure;

[0025] When the microgrid is a medium- and high-voltage microgrid, the centralized power supply system includes a medium-voltage side centralized power supply system and a high-voltage side centralized power supply system. The high-voltage side centralized power supply system is connected to the high-voltage busbar and uses high-voltage energy to supply power to the outside; the medium-voltage side centralized power supply system is connected to the medium-voltage busbar and uses medium-voltage energy to supply power to the outside. According to the requirements for power supply reliability and the degree of political and economic losses or impacts caused by power outages, the power loads in the microgrid are classified into primary loads, secondary loads, and tertiary loads. The primary load is an important load inside the microgrid, and the power supply cannot be interrupted when the microgrid is off-grid.

[0026] The loads in each sub-microgrid system must include the first-level load, while other levels of power loads in the microgrid can be allocated to all or part of the sub-microgrid systems according to actual conditions.

[0027] The sub-microgrid system also includes a mobile energy storage device;

[0028] When the corresponding sub-microgrid system is insufficient to support the power supply of the primary load, the local controller controls the corresponding sub-microgrid system to connect to the corresponding mobile energy storage device;

[0029] Among them, high-voltage energy / medium-voltage energy includes distributed energy, which can be clean energy such as photovoltaics, wind power, natural gas, biomass fuels, etc. Low-voltage energy includes distributed energy and energy storage devices, which can be clean energy such as photovoltaics, wind power, natural gas, biomass fuels, etc., and energy storage devices can be lithium-ion energy storage battery packs, etc.

[0030] The mobile energy storage device includes charging piles, generators and new energy vehicles. The new energy vehicles reversely supply power to the sub-microgrid system through the charging piles. During the operation of the sub-microgrid, the new energy vehicles can reversely provide the energy they carry to the sub-microgrid through different charging piles.

[0031] The microgrid and several sub-microgrid systems are connected through an optical fiber network, enabling the central controller to quickly exchange information with local controllers.

[0032] A microgrid control method, applied to a microgrid system;

[0033] The central controller and several local controllers monitor the operating status of the microgrid in real time, collect and summarize various operating data, and adjust the operating status of the microgrid at any time.

[0034] The central controller determines that the microgrid is disconnected from the main grid, and the central controller sends information to several sub-microgrid systems through the optical fiber network, and several sub-microgrids enter the off-grid operation mode;

[0035] The central controller determines that the microgrid is closed to the main grid. The central controller sends information to several sub-microgrid systems through the optical fiber network, and several sub-microgrids enter the grid-connected operation mode.

[0036] The local controllers in the plurality of sub-microgrids receive control instructions from the central controller to control the sub-microgrids to operate in a grid-connected operation mode or an off-grid operation mode.

[0037] During operation, several local controllers simultaneously collect power consumption and discharge power in the corresponding sub-microgrid, obtain a first critical power value at the power consumption end and a second critical power value at the discharge end, and adjust the discharge power according to the first critical power value and the second critical power value.

[0038] like Figure 1 As shown, a microgrid control method includes:

[0039] Step A1: The central controller detects whether the microgrid is off-grid. When the central controller detects that the microgrid is off-grid, the process proceeds to step A2. Otherwise, the process returns to step A1.

[0040] Step A2: The central controller sends the level of each power load to the local controller of the sub-microgrid system to which the power load belongs, and distributes the energy output by the centralized power supply system to each sub-microgrid system. Optionally, the central controller sends the level of each power load to the local controller of the sub-microgrid system to which the power load belongs through an optical fiber ring network communication method;

[0041] Step A3: The local controller of the sub-microgrid system calculates the power supply capacity and power supply time of the sub-microgrid system when the microgrid is off-grid, and obtains a calculation result; wherein, when the microgrid is off-grid, the sub-microgrid system uses the energy distributed by the centralized power supply system and the energy output by the low-voltage power supply in the sub-microgrid system as an energy source;

[0042] Step A4: The local controller of the sub-microgrid system controls the sub-microgrid system to preferentially supply power to the high-level power loads in the sub-microgrid system according to the calculation results.

[0043] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A microgrid control system, characterized in that: The microgrid includes a centralized power supply system and multiple sub-microgrid systems, the centralized power supply systems are all distributed energy sources, the sub-microgrid systems are composed of low-voltage energy sources and loads, the loads include primary loads, and the low-voltage energy sources include distributed energy sources and energy storage devices; The microgrid control system consists of a central controller and several local controllers, wherein the several local controllers are distributed corresponding to each sub-microgrid system, and the central controller stores all power load levels in the microgrid, and is used to distribute the energy in the centralized power supply system to each sub-microgrid system according to each power load level when the microgrid is switched to off-grid operation; When the microgrid is operating off-grid, the sub-microgrid system uses the centralized power supply system and the low-voltage energy as energy sources, and several local controllers calculate the power supply energy size and power supply time of the corresponding sub-microgrid system when the microgrid is operating off-grid, and allocate the low-voltage energy in the sub-microgrid system according to the calculation structure to power high-level power loads.

2. A microgrid control system according to claim 1, characterized in that: The sub-microgrid system also includes a mobile energy storage device; When the corresponding sub-microgrid system is insufficient to support the power supply of the primary load, the local controller controls the corresponding sub-microgrid system to connect to the corresponding mobile energy storage device.

3. A microgrid control system according to claim 1, characterized in that: The mobile energy storage device includes a charging pile, a generator and a new energy vehicle, and the new energy vehicle supplies reverse power to the sub-microgrid system through the charging pile.

4. A microgrid control system according to claim 1, characterized in that: The microgrid and the plurality of sub-microgrid systems are connected via an optical fiber network.

5. A microgrid control method, characterized in that: Application and microgrid system; The central controller and the local controllers monitor the operating status of the microgrid in real time, collect and summarize various operating data, and adjust the operating status of the microgrid at any time.

6. A microgrid control method according to claim 5, characterized in that: The central controller determines that the microgrid is disconnected from the main grid, and the central controller sends information to the plurality of sub-microgrid systems through the optical fiber network, and the plurality of sub-microgrids enter an off-grid operation mode; The central controller determines that the microgrid is closed to the main grid, and the central controller sends information to the plurality of sub-microgrid systems through the optical fiber network, and the plurality of sub-microgrids enter a grid-connected operation mode.

7. A microgrid control method according to claim 5, characterized in that: The local controllers in the plurality of sub-microgrids receive control instructions from the central controller to control the sub-microgrids to operate in a grid-connected operation mode or an off-grid operation mode.

8. A microgrid control method according to claim 5, characterized in that: Some of the local controllers run During the process, the power consumption and discharge power in the corresponding sub-microgrid are collected simultaneously to obtain the first critical power value of the power consumption end. and a second critical power value at the discharge end, and adjusting the discharge power according to the first critical power value and the second critical power value.

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