CN213185533U - A multi-mode energy storage microgrid - Google Patents

Abstract

The utility model discloses a multi-mode energy storage microgrid, comprising m groups of photovoltaic components, fans and energy storage units connected in parallel to a primary bus of the microgrid, and a control unit electrically connected with the photovoltaic components, the fan and the energy storage units respectively. The control system includes n integrated optical storage machines, fan control cabinets, photovoltaic inverters and energy storage converters; wherein, n integrated optical storage machines are connected to the primary bus of the microgrid through a controllable switch, m>n≥ 1. The energy storage system is equipped with lead-carbon batteries/lithium iron phosphate batteries and super capacitors; n groups of photovoltaic modules and lead-carbon batteries/lithium iron phosphate batteries are connected in parallel to the integrated light-storage machine, and the supercapacitors are connected to the primary through the energy storage converter. busbar. The micro-grid system of the utility model adopts the integrated design of photovoltaic and energy storage and conversion, and has stable operation and reliable performance. The battery performance of the hybrid energy storage is different, and the advantages are complementary. Power fluctuation support.

Description

A multi-mode energy storage microgrid

technical field

The utility model belongs to the technical field of new energy power generation, and in particular relates to a micro-grid system for energy storage by means of an integrated light-storage machine, a super capacitor and the like.

Background technique

With the rapid development of new energy, the microgrid system emerges as the times require. Microgrid is the core structure of the energy Internet and an important support for the future energy transformation and development, especially under the dual pressures of environmental protection and energy structure adjustment, including clean energy The microgrid technology has been widely researched and applied. The microgrid system is a set of systems built on the basis of distributed photovoltaic, wind power generation systems, energy storage units, various loads and other electrical units. Photovoltaic modules are greatly affected by environmental factors, so energy storage equipment is an indispensable component to maintain the power balance of the system. As a key link in the microgrid system, it can store intermittent renewable energy such as solar energy and wind energy. . At the same time, the access of the energy storage equipment provides the possibility for the flexible switching operation of the photovoltaic power generation system between off-grid and grid-connected modes.

With the increasing number of non-linear loads and other electrical equipment, the microgrid system has problems such as low power factor and serious harmonic pollution, which reduces the utilization efficiency of electric energy in the microgrid system, overheating of electrical equipment, and shortened service life of electrical components. . Moreover, since the output power of the photovoltaic field will change the power flow distribution of the original power system, the transmission power of the line and the inertia of the whole system to a certain extent, it will have an impact on the voltage stability of the power grid.

Energy storage technology solves the volatility and randomness of new energy power generation to a large extent, and effectively improves the predictability, certainty and economy of intermittent micro-sources. In addition, the energy storage technology can regulate frequency and voltage, improve the balance of active power and reactive power of the system, and improve the stable operation ability of the microgrid. In a power system with a high penetration rate of wind and solar power generation, when the frequency and voltage of the power system change, the wind-solar storage cluster is required to have strong real-time performance on the stability and power quality of the power system. It must be fully considered according to the real-time state of the power system. Only the adjustment ability of the wind-solar storage cluster can ensure the reliable and economical operation of the power system. The traditional photovoltaic energy storage power generation system is mainly composed of multiple converters. The unavoidable influence of harmonics after the parallel connection of multiple converters brings many disadvantages to the AC parallel system. The device cannot support the microgrid voltage and frequency.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems of the prior art, the present invention provides a multi-mode energy storage microgrid, comprising m groups of photovoltaic components, fans, and energy storage units connected in parallel to the primary bus of the microgrid, and A control system in which photovoltaic modules, fans and energy storage units are electrically connected, characterized in that the control system includes n integrated optical storage machines, fan control cabinets, photovoltaic inverters and energy storage converters; wherein,

The n integrated optical storage machines are connected to the primary bus of the microgrid through a controllable switch, m>n≥1;

The energy storage unit is configured with a lead-carbon battery/lithium iron phosphate battery and a super capacitor; n groups of the photovoltaic modules and the lead-carbon battery/lithium iron phosphate battery are connected in parallel to the optical storage integrated machine, and the super capacitor is An energy storage converter is connected to the primary bus.

Further, at least one of the integrated optical storage machines is connected to the photovoltaic module and the lead-carbon battery, respectively.

Further, at least one of the integrated optical storage machines is connected to the photovoltaic module and the lithium iron phosphate battery, respectively.

Further, the control system includes a distributed power generation control unit, and the distributed power generation control unit includes two integrated optical-storage machines, wherein one of the integrated optical-storage machines is respectively connected to the photovoltaic module and the lead-carbon battery, The other integrated optical storage machine is respectively connected with the photovoltaic module and the lithium iron phosphate battery.

Further, the control system of the micro-grid further includes a transformer, and the integrated optical-storage machine is connected to the primary bus of the micro-grid via a controllable switch and a transformer.

Further, the m-n groups of photovoltaic modules are connected to the primary busbar through the photovoltaic inverter.

Advantages of the utility model:

The microgrid system adopts the integrated design of photovoltaic, energy storage and conversion, with stable operation, reliable performance, independent energy management function, support for intelligent charging and discharging, support for three-phase 100% unbalanced operation with load, parallel and off-grid operation modes It has real-time scheduling of active and reactive power and low voltage ride-through function (when running on-grid), with short-circuit support and self-recovery function (when running off-grid). Hybrid energy storage batteries have different performance and complementary advantages. Energy-type batteries provide voltage support, and power-type batteries provide power fluctuation support.

Description of drawings

FIG. 1 is a schematic structural diagram of a multi-mode energy storage microgrid of the present invention.

FIG. 2 is a basic principle block diagram of the optical storage integrated converter of the present invention.

FIG. 3 is a schematic diagram of the photovoltaic power generation connected to the microgrid of the present invention.

Detailed ways

Embodiments of the invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but not to be construed as a limitation of the present invention.

As shown in FIG. 1, the multi-mode energy storage microgrid of the present invention includes distributed power sources, such as m groups of photovoltaic modules 1, fans 2, etc., which are connected in parallel with the energy storage units to the primary bus of the microgrid, The distributed power generation source and the energy storage unit are respectively connected with the primary bus of the microgrid through a control system and a controllable switch. In Figure 1, 10kV/380V is a transformer, AC380V is a low-voltage AC bus, L1-L5 represents the branch line on the power side of the microgrid, L1-1, L1-2, L1-3 represent the mains power supply line, L2-1, L2- 2. L2-3 represents the microgrid power supply line, S1-S3 represents the dual power circuit breaker, and K1-K5 represents the intelligent control switch. Workflow of Lines 1 and 2: Lines 1 and 2 are the mains power supply and serve as backup for each other. When the microgrid is not put into use, S1-S3 are connected to the mains lines L1-1, L1-2, and L1-3 respectively, and the mains supply power to the electricity load; when the microgrid is put into use, S1-S3 are automatically switched It is connected to L2-1, L2-2, and L2-3, and the microgrid supplies power to the load, and maintains the normal and stable operation of the microgrid system according to the microgrid and off-grid operation strategy.

The control system includes distributed power generation control units, such as n integrated optical storage machines, fan control cabinets, photovoltaic inverters, and energy storage converters (Power Control System, PCS). Each distributed power generation control unit, Before the energy storage converter is connected to the primary bus of the microgrid, there is a controllable switch for on-grid and off-grid control.

Optical storage integrated machine 3, namely optical storage integrated converter, integrates the functions of inverter and energy storage PCS. It is the link between the power grid and photovoltaic power generation and electrical energy storage equipment. It shoulders the role of charging and electrical energy feedback. . The basic principle block diagram of the optical-storage integrated converter is shown in Figure 2. The optical storage integrated machine 3 is mainly composed of two DC/DC converters on the photovoltaic side and the energy storage side, and a DC/AC converter on the load side. Among them, the photovoltaic side converter converts the voltage generated by the photovoltaic modules into the voltage required by the DC bus; the energy storage side converter enables bidirectional flow of energy, and in the grid-connected mode, the energy-storage-side converter charges the battery; in the off-grid mode The energy storage side converter acts as a battery to charge the DC bus to keep the bus voltage constant; the DC/AC converter adopts a T-type three-level topology, which can operate in grid-connected mode and off-grid mode according to the working state of the grid. . The n groups of photovoltaic modules 1 are connected in parallel with the energy storage battery on the DC side, and then inverted and boosted by the integrated optical storage machine, and then connected to the microgrid through the controllable switch 4 and the transformer 5 to realize grid-connected power generation. The transformer 5 can be used Double winding transformer. Its connection to the microgrid is shown in Figure 3.

The number and capacity of the integrated optical storage machines 3 are determined according to the number of photovoltaic modules 1 to be connected and the power generation amount.

In order to ensure that the microgrid can continue to ensure the power supply demand of each load in the event of a power failure of the large grid, the microgrid system is also equipped with an energy storage unit of a lead-carbon battery 5, a combination of lithium iron phosphate battery 6 and a super capacitor 7. The energy storage unit also has the functions of smoothing the output of photovoltaic wind turbines, absorbing surplus photovoltaic energy, and participating in peak shaving and valley filling of the power grid. The energy storage unit is configured with a lead-carbon battery/lithium iron phosphate battery and a super capacitor; n groups of the photovoltaic modules and the lead-carbon battery/lithium iron phosphate battery are connected in parallel to the optical storage integrated machine, and the super capacitor 7 connected to the primary bus through an energy storage converter. The distributed generation power inside the microgrid is self-generated and used by itself. When the generated power is greater than the load power, the excess part is given priority to charging the energy storage, and the rest is connected to the grid; when the generated power is less than the load power, the energy storage is discharged to supplement the power shortage, such as If the energy storage is not enough to make up for the power shortage, it will be supplemented by taking electricity from the grid.

In the microgrid system, the energy storage mainly plays the role of smoothing the distributed generation output and performing peak shaving and valley filling during normal grid connection. In emergency situations and some specific control conditions, the energy storage acts as a backup power source.

When the microgrid runs off-grid, the energy storage acts as the main power source to provide the reference frequency for the microgrid. In order to ensure the stable operation of the microgrid off-grid, by coordinating the distribution among distributed power sources, loads, and energy storage, the stable operation of the microgrid off-grid is realized, and the important load can be reliably operated for a certain period of time.

Example

As shown in FIG. 1 , the utility model is applied to a university, and the photovoltaic modules 1 connected to the microgrid of the utility model are mainly teaching buildings No. 1, 2 and 3, a comprehensive building for graphic and textual information, an academic exchange and affairs center, an energy Roof photovoltaics in six buildings including the School of Mechanical Engineering. The microgrid uses 2 integrated optical storage machines with a capacity of 150kW and 100kW respectively. The rooftop photovoltaics of the No. 1 and 2 teaching buildings and the graphic information complex are connected to the microgrid through the integrated optical storage machine, and the roofs of the other buildings are connected to the microgrid. The photovoltaic is connected to the microgrid bus through the photovoltaic inverter. It also includes a fan 2 and an energy storage unit, which are connected to the microgrid bus through the fan control cabinet and the energy storage PCS.

The photovoltaic capacity of the campus is 478KW. The important loads of the campus include the data center and data center air conditioners. In the case of off-grid, it is necessary to ensure a reliable power supply for 2 hours, and the photovoltaic capacity connected to the integrated optical storage machine is 235.2kW. The configured energy storage unit capacity It is: 250kW×2h lead-carbon battery 5/lithium iron phosphate battery 6, and a 100kW*10s supercapacitor 7 for energy storage to meet the needs of rapid power regulation. The 150kW integrated light-storage machine is connected to the photovoltaic module and the lead-carbon battery 5 respectively, and the 100kW integrated light-storage machine is connected to the photovoltaic module and the lithium iron phosphate battery 6 respectively. In the case of off-grid or main network failure, priority is given to supplying power to important loads such as data centers. At this time, the 150kW optical-storage integrated machine provides the reference voltage and frequency for the AC bus, and the 100-kW optical-storage integrated machine works in the P/Q mode (ie, the output power control mode), giving priority to ensuring the reliable power supply of the data center. In addition, the super capacitor 7 is rapidly charged and discharged to cope with the short-term power fluctuation of the air conditioning load of the data center.

The charge and discharge rates of lead-carbon batteries and lithium iron phosphate batteries are not much different. The normal discharge rate of lead-carbon batteries is 0.5C, and the charge-discharge rate of lithium iron phosphate batteries is about 1C. The capacity should be as close as possible to the capacity configuration of the lithium iron phosphate battery. The lead-carbon battery capacity configuration is 150kW/300kWh, the single battery capacity is 2V/1000Ah, and it is connected to the battery side input end of the 150kW optical storage integrated machine; the lithium iron phosphate battery capacity configuration is 100kW/200kWh, and the single battery capacity is configured. It is 3.2V/200Ah and is connected to the battery side input terminal of the 100kW optical storage integrated machine. The input voltage of the two types of batteries is between 250V and 520V.

The discharge depth of lead-carbon batteries is 80%, and the actual discharge capacity of 300kWh lead-carbon batteries is 240kWh, so the voltage range of multi-cell lead-carbon batteries in series is between 263V and 352V, and the rated voltage is 300V, which meets the requirements of optical storage integrated machine storage. Energy side input voltage range.

The discharge depth of the lithium iron phosphate battery is 90%, and the actual discharge capacity of the 200kWh lithium iron phosphate battery is 180kWh. Therefore, the voltage range of the multi-cell lithium iron phosphate battery through series and parallel is between 281V and 380V, and the rated voltage is 332V. The input voltage range of the energy storage side of the optical storage integrated machine.

The microgrid is also configured with multiple series-connected 48V165F supercapacitors, and the PCS used in the supercapacitor is a single panel cabinet.

In addition to supplying power to the user's load during the day, the excess energy is stored in the energy storage unit; at night, the energy storage unit is appropriately arranged to release part of the energy, so that there is appropriate space for re-storage during the next day.

The utility model adopts the scheme of an integrated light-storage machine and a mixed energy-storage device, and includes a lead-carbon battery and a lithium iron phosphate energy type battery and a super capacitor power type battery. Photovoltaic-storage integrated machine adopts the way that photovoltaic and energy storage are collected through the DC/DC common DC bus, with flexible control and high stability. It can not only realize photovoltaic MPPT (maximum power point tracking) control, but also adapt to different types of energy storage. , give full play to the adjustment range of energy storage, optimize the charge and discharge control of energy storage, and improve the utilization rate of energy. Energy-type batteries are mainly used to support the AC bus voltage. Through their own charging and discharging strategies, they can meet the slow power changes in the micro-grid and achieve stable operation of the micro-grid; while the power-type batteries are used to cope with fast and large power on the bus. Fluctuations, super capacitors can release or absorb relatively large power in a short time to smooth the power fluctuations on the bus.

Claims (6)

1. A multi-mode energy storage microgrid, comprising m groups of photovoltaic assemblies, fans, and energy storage units connected in parallel to a primary bus of the microgrid, and electrically connected to the photovoltaic assemblies, fans, and energy storage units respectively. A control system, characterized in that the control system includes n integrated optical storage machines, fan control cabinets, photovoltaic inverters and energy storage converters; wherein, The n integrated optical storage machines are connected to the primary bus of the microgrid through a controllable switch, m>n≥1; The energy storage unit is configured with a lead-carbon battery/lithium iron phosphate battery and a super capacitor; n groups of the photovoltaic modules and the lead-carbon battery/lithium iron phosphate battery are connected in parallel to the optical storage integrated machine, and the super capacitor is An energy storage converter is connected to the primary bus. 2 . The microgrid according to claim 1 , wherein at least one of the integrated light-storage machines is connected to the photovoltaic module and the lead-carbon battery, respectively. 3 . 3 . The microgrid according to claim 1 , wherein at least one of the integrated optical storage machines is connected to the photovoltaic module and the lithium iron phosphate battery, respectively. 4 . 4. The microgrid according to claim 1, wherein the control system comprises a distributed power generation control unit, and the distributed power generation control unit comprises two integrated optical storage machines, wherein one of the integrated optical storage machines is respectively is connected with the photovoltaic component and the lead-carbon battery, and the other integrated light-storage machine is connected with the photovoltaic component and the lithium iron phosphate battery respectively. 5 . The microgrid according to claim 1 , wherein the control system of the microgrid further comprises a transformer, and the integrated optical-storage machine is connected to the primary bus of the microgrid via a controllable switch and a transformer. 6 . 6 . The microgrid according to claim 1 , wherein the m-n groups of photovoltaic modules are connected to the primary bus through the photovoltaic inverter. 7 .

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