Optical-storage direct-flexible intelligent direct-current micro-grid system

Abstract

The utility model relates to the technical field of optical storage direct-current flexible, and provides an optical storage direct-current flexible intelligent direct-current micro-grid system, which comprises a solar photovoltaic power generation unit, a direct-current load, an energy storage unit, an alternating-current load and a power grid, the solar photovoltaic power generation unit is connected with one or more of a direct current load or an energy storage unit or an alternating current load or a power grid through a DC750V direct current power distribution network; according to the utility model, through comprehensive regulation and control of the photovoltaic panel, the energy storage unit, the DC load and the AC load, self-regulation and flexible correspondence of the building energy utilization system are realized, power generation (or power utilization) power fluctuation of an external network is small and predictable, the difficulty of power grid dispatching is greatly reduced, demand side response of the power grid can be participated under certain conditions, and the system is suitable for popularization and application. New electric charge income is realized; meanwhile, the direct current tolerated by the human body is 2-4 times higher than the alternating current, so that the electricity utilization is safer; meanwhile, the system enriches the flexibility and selectivity of power supply.

Description

Technical Field

[0001] The utility model relates to the field of photovoltaic storage direct current and flexible power supply, and in particular to a photovoltaic storage direct current and flexible power supply intelligent direct current microgrid system. Background Art

[0002] Photovoltaic and other renewable energy sources generally generate direct current, while the electricity used in daily life is alternating current. Common photovoltaic buildings will install inverters to convert direct current into alternating current for daily use. Compared with conventional photovoltaic buildings, photovoltaic DC buildings have the advantages of high energy utilization rate (increased by 6-8%), obvious energy-saving advantages, low equipment investment, and short investment recovery period (eliminating inverters, transformers and other equipment, saving 10% of initial equipment investment). However, during the conversion process, electricity loss will occur.

[0003] The application of direct current in buildings can significantly improve the performance of the system, enhance the quality and safety of the power supply, and effectively solve the two major problems faced by the new zero-carbon power system in developing wind power and photovoltaic power on a large scale: photovoltaic installation space and wind power and photovoltaic power regulation. It is an effective way to dispatch resources from all aspects and assist the construction of new zero-carbon power systems at a lower cost, and it is also an effective measure to achieve full electrification of buildings and zero-carbon electricity use. Utility Model Content

[0004] The utility model proposes a photovoltaic-storage-direct-flexible intelligent DC microgrid system, which realizes self-regulation and flexible response of the building energy system through comprehensive regulation of photovoltaic panels, energy storage units, DC loads and AC loads, and has small and predictable power fluctuations in external grid power generation (or power consumption), greatly reducing the difficulty of grid dispatching. Under certain conditions, it can also participate in the demand-side response of the grid and realize new electricity bill income. At the same time, since the human body can tolerate DC current 2-4 times higher than AC current, electricity use is guaranteed to be safer. At the same time, the system enriches the flexibility and selectivity of power supply.

[0005] The technical solution of the utility model is achieved in this way:

[0006] A photovoltaic storage direct-flexible intelligent DC microgrid system is connected to the nearest transformer;

[0007] Including: solar photovoltaic power generation unit, DC load, energy storage unit, AC load and power grid (existing power grid);

[0008] The solar photovoltaic power generation unit is connected to one or more of a DC load, an energy storage unit, an AC load or a power grid through a DC750V DC distribution network;

[0009] The solar photovoltaic power generation unit includes a photovoltaic conversion energy router and a photovoltaic panel. The photovoltaic panel is connected to the photovoltaic conversion energy router, and the photovoltaic conversion energy router is connected to the DC750V direct current distribution network.

[0010] Furthermore, three photovoltaic conversion energy routers (50KW) are provided, and each photovoltaic conversion energy router is equipped with a set of photovoltaic panels.

[0011] Further, the DC load includes one or more of a DC water pump, a magnetic suspension refrigerator, a lighting device or a socket;

[0012] The DC water pump is connected to the DC750V DC distribution network through a first DC / DC converter;

[0013] The lighting device is connected to the DC750V direct current distribution network via a second DC / DC converter;

[0014] The socket is connected to the DC750V direct current distribution network through a third DC / DC converter.

[0015] Furthermore, the DC750V direct current distribution network is connected to the alternating current load via a flexible bidirectional converter.

[0016] Further, the energy storage unit includes an energy storage system and an energy storage bidirectional converter;

[0017] The energy storage bidirectional converter is connected to the DC750V direct current distribution network;

[0018] The energy storage system is connected to the energy storage bidirectional converter.

[0019] Further, the AC load includes an automatic dosing device, a water treatment device and an air source heat pump;

[0020] The air source heat pump, water treatment device and automatic dosing device are all connected to the DC750V direct current distribution network through the flexible bidirectional converter (250kVA);

[0021] The water treatment device is connected to the air source heat pump;

[0022] The automatic dosing device is connected to the water treatment device.

[0023] Furthermore, the flexible bidirectional converter is simultaneously connected to AC 380V mains electricity.

[0024] Furthermore, the DC load includes one or more of a DC water pump, a magnetic suspension refrigerator, a lighting device or a socket.

[0025] Furthermore, the lighting device and the socket are also connected to a DC220V direct current power supply;

[0026] The DC220V direct current power supply is simultaneously connected to the DC750V direct current distribution network through a fourth DC / DC converter.

[0027] The utility model has the following advantages:

[0028] 1. Create green buildings - through building roofs or curtain wall photovoltaics, the building itself can be energy self-sufficient to the greatest extent. Using low-voltage direct current to absorb new energy is more friendly to the power grid and is not subject to the restrictions on transfer capacity by the power grid company. Low-voltage direct current has also been included in the green building evaluation standards of China and the United States.

[0029] 2. Improved clean energy utilization rate - because photovoltaic, energy storage and a large number of power-consuming equipment have been converted to DC, low-voltage DC networking is directly adopted, which reduces the repeated conversion between AC and DC and improves efficiency (compared with traditional AC, the utilization efficiency can be increased by more than 10%);

[0030] 3. Reduce the comprehensive cost of power generation and electricity consumption - reduce power consumption capacity (fees) and line losses, simplify the procedures for grid connection of new energy power generation, and self-use also reduces electricity costs;

[0031] 4. Promote the intelligent use of electricity in buildings - DC power distribution - Each link in the system can realize the observability and control of power consumption through digital interfaces, making the building power distribution system truly intelligent;

[0032] 5. Create flexibility in building electricity use - through the comprehensive regulation of photovoltaics, energy storage, and loads, the building energy system can be self-regulated and flexible, with small and predictable power fluctuations in external power generation (or power consumption), which greatly reduces the difficulty of grid dispatching. Under certain conditions, it can also participate in the demand-side response of the grid and realize new electricity fee income;

[0033] 6. Ensure safer electricity use - compared with AC, the human body's ability to withstand DC leakage current is 2-4 times higher than that of AC current, so electricity use is safer, and by adjusting the system grounding method, theoretically, the current passing through the human body can be completely controlled within a safe level, completely eliminating the phenomenon of power storage;

[0034] 7. Enriched the flexibility and selectivity of power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 This is a structural schematic diagram of a photovoltaic storage direct-flexible intelligent direct-current microgrid system in a specific embodiment of the utility model;

[0037] Explanation of the reference numerals: solar photovoltaic power generation unit 1; photovoltaic conversion energy router 11; photovoltaic panel 12; DC load 2; DC water pump 21; first DC / DC converter 211; magnetic levitation refrigerator 22; lighting device 23; second DC / DC converter 231; socket 24; third DC / DC converter 241; energy storage unit 3; energy storage system 31; energy storage bidirectional converter 32; AC load 4; air source heat pump 41; water treatment device 42; automatic dosing device 43; power grid 5; DC750V DC distribution network 6; DC220V DC power supply 9; fourth DC / DC converter 91. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0039] In the specific embodiment of the present invention, see Figure 1 , a photovoltaic storage direct-flexible intelligent DC microgrid system, connected to the nearest transformer;

[0040] It includes: a solar photovoltaic power generation unit 1, a DC load 2, an energy storage unit 3, an AC load 4 and a power grid 5 (which is an existing power grid);

[0041] The solar photovoltaic power generation unit 1 is connected to one or more of a DC load 2, an energy storage unit 3, an AC load 4, or a power grid 5 via a DC 750V DC distribution network 6;

[0042] The solar photovoltaic power generation unit 1 includes a photovoltaic conversion energy router 11 and a photovoltaic panel 12. The estimated installed capacity of the photovoltaic panel 12 is 150kWp. The photovoltaic panel 12 is connected to the photovoltaic conversion energy router 11, and the photovoltaic conversion energy router 11 is connected to the DC750V direct current distribution network 6.

[0043] In the specific embodiment of the present utility model, see Figure 1 There are three photovoltaic conversion energy routers (50KW) 11, and each photovoltaic conversion energy router is equipped with a set of photovoltaic panels 12.

[0044] In the specific embodiment of the present utility model, see Figure 1 , the DC load 2 includes one or more of a DC water pump 21, a magnetic suspension refrigerator 22, a lighting device 23 or a socket 24;

[0045] The DC water pump 21, the lighting device 23 and the socket 24 are all connected to the DC750V DC distribution network 6 via a DC / DC converter;

[0046] The DC water pump 21 is connected to the DC 750V DC distribution network 6 via a first DC / DC converter 211;

[0047] The lighting device 23 is connected to the DC750V DC distribution network 6 via a second DC / DC converter 231;

[0048] The socket 24 is connected to the DC 750V direct current distribution network 6 via a third DC / DC converter 241 .

[0049] In the specific embodiment of the present utility model, see Figure 1 The DC750V DC distribution network 6 is connected to the AC load 4 via a flexible bidirectional converter 7 .

[0050] In the specific embodiment of the present utility model, see Figure 1 , the energy storage unit 3 includes an energy storage system 31 and an energy storage bidirectional converter 32;

[0051] The energy storage bidirectional converter 32 is connected to the DC750V DC distribution network 6;

[0052] The energy storage system 31 is connected to the energy storage bidirectional converter 32 .

[0053] In the specific embodiment of the present utility model, see Figure 1 , the AC load 4 includes an automatic dosing device 43, a water treatment device 42 and an air source heat pump 41;

[0054] The air source heat pump 41, the water treatment device 42 and the automatic dosing device 43 are all connected to the DC750V DC distribution network 6 via a flexible bidirectional converter (250kVA) 7;

[0055] The water treatment device 42 is connected to the air source heat pump 41;

[0056] The automatic dosing device 43 is connected to the water treatment device 42 .

[0057] In the specific embodiment of the present utility model, see Figure 1 , the flexible bidirectional converter 7 is simultaneously connected to the AC 380V 8 mains power;

[0058] When there is excess electricity, it is connected to the AC distribution network through a distribution transformer and sold to the grid.

[0059] In the specific embodiment of the present utility model, see Figure 1 The DC load 2 includes one or more of a DC water pump 21 , a magnetic suspension refrigerator 22 , a lighting device 23 or a socket 24 .

[0060] In the specific embodiment of the present utility model, see Figure 1 The lighting device 23 and the socket 24 are also connected to a DC220V direct current power supply 9;

[0061] The DC220V direct current power source 9 is also connected to the DC750V direct current distribution network 6 through the fourth DC / DC converter 91 .

[0062] In this application:

[0063] (1) Photovoltaic conversion energy router, which includes a photovoltaic converter (150kW, full-load MPPT voltage range 580V-750V), a drawer switch, and is equipped with DC microcomputer protection and DC multi-function meter;

[0064] (2) DC220V power supply, including 2 drawer switches, equipped with DC microcomputer protection module (DC750V / DC220V, 60kW, isolated type) and DC multi-function meter, with DC active protection function;

[0065] (3) Insulation monitoring device, responsible for monitoring the DC distribution system, monitoring photovoltaic power generation, monitoring the energy storage unit, and system operation strategy and control;

[0066] (4) Flexible bidirectional converters are used to connect DC power grids with AC power grids. They can be controlled by control strategies for bidirectional flow, unidirectional flow, grid connection, and off-grid operation. They are important devices for achieving the connection of surplus power to the grid and power draw from the grid.

[0067] In the specific embodiment of the present utility model, see Figure 1 In the specific embodiment of the present application, the following power distribution modes are included, and the operation of each functional mode is described as follows:

[0068] (1) System operation mode

[0069] The system can automatically or manually switch between operation modes: economic operation mode, limited function mode, demand-side response mode, emergency energy storage mode, and off-grid mode;

[0070] (2) Economic operation model

[0071] To ensure the best economic performance of the entire system and maximize the benefits of power generation, power consumption and power storage, the DC load plus the AC load should first absorb the photovoltaic output; when there is excess photovoltaic power, it can be stored on site, and after the energy storage unit is fully charged, there is still excess power to directly supply the power grid; when photovoltaic power is insufficient, the energy storage will make up for the DC load or AC load demand; when the energy storage is insufficient, it will be supplemented by the external network; in order to reduce the grid connection management requirements for the power grid company, buildings using DC distribution do not need to return power to the grid; when their own power cannot meet the demand, they can draw power from the grid in real time to balance the power demand;

[0072] (3) External network power limited operation mode

[0073] When the command is issued, the system first consumes the photovoltaic output (to supply power to the load and energy storage). If it is insufficient, it will be provided by the energy storage unit. If it is insufficient, it will obtain power from the grid. If the power demanded from the grid exceeds the limit, part of the load will be removed according to the pre-set load priority or power consumption strategy. This is also a kind of demand-side response.

[0074] (4) Demand-side response model

[0075] By controlling energy storage and load, the demand side can respond to the short-term requirements of the power grid, such as reducing the power demand for the grid, shedding loads, releasing energy storage, and even returning power to support the large power grid;

[0076] (5) Emergency charging mode

[0077] When the large power grid or new energy generation may not be able to meet the power demand in the short term, it is necessary to maximize the storage of electric energy in advance and release it only in emergency situations to meet the use of important loads during the special emergency period;

[0078] (6) Off-grid operation mode

[0079] When there is no large power grid (no power supply area or when the large power grid fails and is disconnected), it is in an isolated "generation-storage-distribution-use" self-balancing state; the batteries and photovoltaics in the storage unit bear all the loads, and the power consumption strategy can be set according to the load level to schedule or cut off the load.

[0080] This application has the following advantages:

[0081] 1. Promote the low-carbon development of the entire energy system. In the future, under the development requirements of low-carbon energy, buildings will no longer be just electricity loads in the traditional sense, but will have functions such as power generation, energy storage, regulation, and electricity consumption. "PV-storage-direct-flexible" buildings are an important technical path to promote buildings to assume the above comprehensive functions;

[0082] 2. An effective mechanism or model to achieve building-grid friendly relations;

[0083] 3. The "solar-storage-direct-flexible" buildings can be included in the corresponding user-side load dispatching system of a larger scope and scale such as load aggregators, so as to achieve the goal of making the buildings an adjustable flexible load in the power system.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A solar-storage-direct-flexible intelligent DC microgrid system connected to the nearest transformer; Features: Includes solar photovoltaic power generation units, DC loads, energy storage units, AC loads and power grids; The solar photovoltaic power generation unit is connected to one or more of a DC load, an energy storage unit, an AC load or a power grid through a DC750V DC distribution network; The solar photovoltaic power generation unit includes a photovoltaic conversion energy router and a photovoltaic panel, the photovoltaic panel is connected to the photovoltaic conversion energy router, and the photovoltaic conversion energy router is connected to the DC750V DC power distribution network; three photovoltaic conversion energy routers are provided, and each photovoltaic conversion energy router is equipped with a set of photovoltaic panels; the DC load includes one or more of a DC water pump, a magnetic suspension refrigerator, a lighting device or a socket; The DC water pump is connected to the DC750V DC distribution network through a first DC / DC converter; The lighting device is connected to the DC750V direct current distribution network via a second DC / DC converter; The socket is connected to the DC750V DC distribution network through a third DC / DC converter; the energy storage unit includes an energy storage system and an energy storage bidirectional converter; The energy storage bidirectional converter is connected to the DC750V direct current distribution network; The energy storage system is connected to the energy storage bidirectional converter; the DC750V DC distribution network is connected to the AC load through a flexible bidirectional converter; the AC load includes an automatic dosing device, a water treatment device and an air source heat pump; The air source heat pump, water treatment device and automatic dosing device are all connected to the DC750V direct current distribution network through the flexible bidirectional converter; The water treatment device is connected to the air source heat pump; The automatic dosing device is connected to the water treatment device; the flexible bidirectional converter is also connected to the AC380V mains power; the lighting device and the socket are also connected to a DC220V direct current power supply; The DC220V direct current power supply is simultaneously connected to the DC750V direct current distribution network through a fourth DC / DC converter.

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