CN103280840A - Distributed type photovoltaic energy storage system and working method thereof - Google Patents

Abstract

The invention relates to a distributed photovoltaic energy storage system and a working method thereof. The output of a photovoltaic cell array is connected to a DC conversion module, and the output end of the DC conversion module is respectively connected to a grid-connected inverter module, an off-grid inverter module, and an energy storage battery assembly; The input end of the rectification conversion module is connected to the grid, and its output end is connected to the energy storage battery assembly; the input end of the grid-connected inverter module is connected to the output end of the DC conversion module, and its output end is connected to the grid; the DC conversion module and the energy storage battery assembly The output end is connected to the input end of the off-grid inverter module, and the output end of the off-grid inverter module is connected to the load; the energy management system is respectively connected to each module for reasonable control, management and distribution of energy. Maximize the utilization of solar energy, suitable for photovoltaic on-grid/off-grid power generation systems with low and medium power levels, fully combine photovoltaic power generation and energy storage technology, realize intelligent control of photovoltaic and energy storage, effectively improve system power generation efficiency, and reduce losses .

Description

A distributed photovoltaic energy storage system and its working method

technical field

The invention relates to a solar photovoltaic power generation system, in particular to a distributed photovoltaic energy storage system and a working method thereof.

Background technique

Solar energy is rich in resources and widely distributed, and it is the renewable energy with the greatest development potential in the 21st century. With the increasingly serious problems of global energy shortage and environmental pollution, solar photovoltaic power generation has become an emerging industry that is widely concerned and focused on development because of its clean, safe, convenient, and high-efficiency characteristics. Since the 1990s, solar photovoltaic power generation has developed rapidly and has been widely used in aerospace, communications, transportation, and the lives of residents in remote areas.

Solar photovoltaic power generation systems are divided into off-grid photovoltaic power generation systems and grid-connected photovoltaic power generation systems. The off-grid photovoltaic power generation system is mainly composed of solar cell modules, controllers, and batteries. If it supplies power to AC loads, an off-grid inverter is also required. Grid-connected photovoltaic power generation system, that is, the direct current generated by solar modules is directly connected to the public power grid after being converted into alternating current that meets the requirements of the mains through a grid-connected inverter. There are mainly centralized large-scale grid-connected photovoltaic power plants and distributed small-scale grid-connected photovoltaic power generation There are two forms of the system. The main feature of the former is that the generated energy is directly transmitted to the power grid, and the power grid is uniformly deployed to supply power to users. However, this kind of power station has a large investment, a long construction period, and a large area, and it is relatively difficult to develop; while the latter Due to the advantages of small investment, fast construction, small footprint, and strong policy support, it is the mainstream direction for the development of grid-connected photovoltaic power generation systems in the future.

At present, the overall development of solar photovoltaic power generation systems is rapid, but there are still many unfavorable factors that restrict the promotion and application of distributed photovoltaic power generation systems in my country, one of which is the cost of photovoltaic power generation systems. Feasible ways to reduce costs: First, increase the utilization rate of solar energy and find cost-effective ways to maximize the use of solar energy, among which the rational design of the topology of photovoltaic energy storage systems becomes the key. The second is to increase the added value of solar photovoltaic power generation systems, use energy storage batteries to store or release electric energy, reduce the impact of weather, and ensure the reliability and quality of power supply.

Contents of the invention

The present invention is aimed at the problem of high cost of application and popularization of photovoltaic power generation systems, and proposes a distributed photovoltaic energy storage system and its working method, combining the characteristics of the system's flexible switching of on-grid and off-grid operation modes, and ability to provide high-quality electric energy and The high-speed processing capability of the energy management system can realize the maximum power tracking MPPT of the photovoltaic cell array, the charging and discharging control of the battery energy storage component, and the optimal coordinated control of the two distributed power sources, and can complete the independent switching function of on-grid/off-grid power generation, maximizing Improve the utilization rate of solar energy, prolong the service life of energy storage battery components, improve the output power quality of the power generation system, and enhance the stability of the system, thereby improving the overall performance of the photovoltaic power generation system.

The technical solution of the present invention is: a distributed photovoltaic energy storage system, including a distributed power supply medium module, a DC conversion module, a rectification conversion module, a grid-connected inverter module, an off-grid inverter module, and an energy management system; a distributed power supply The medium module includes a photovoltaic cell array and an energy storage battery assembly; the output of the photovoltaic cell array is connected to the DC conversion module, and the output of the DC conversion module is respectively connected to the grid-connected inverter module, the off-grid inverter module, and the energy storage battery assembly; the rectification conversion module The input end is connected to the grid, the output end of the rectification conversion module is connected to the energy storage battery assembly; the input end of the grid-connected inverter module is connected to the output end of the DC conversion module, and the output end of the grid-connected inverter module is connected to the grid; the DC conversion module and the energy storage The output end of the battery module is connected to the input end of the off-grid inverter module, and the output end of the off-grid inverter module is connected to the load; the energy management system is connected to the energy storage medium module, DC conversion module, rectification conversion module, grid-connected inverter Inverter module connection.

The photovoltaic battery management system, the energy storage battery management system, the DC conversion module, the rectification conversion module, the grid-connected inverter module, the off-grid inverter module and the energy management system are bidirectionally connected through communication lines.

The grid-connected inverter module, the off-grid inverter module, the DC conversion module, the rectification conversion module are connected to the photovoltaic cell array and the energy storage battery assembly through a DC bus.

The grid-connected inverter module, the off-grid inverter module, and the rectification conversion module are connected to the grid and the load through an AC bus.

The photovoltaic cell array is composed of crystalline silicon solar cell modules connected in series or in parallel.

The grid-connected inverter module includes a grid-connected inverter and a grid-connected protection circuit, and the off-grid inverter module includes an off-grid inverter and an off-grid protection circuit.

A working method of a distributed photovoltaic energy storage system, including a distributed photovoltaic energy storage system, a photovoltaic battery management system is installed in a photovoltaic cell array, and an energy storage battery management system is installed in an energy storage battery module, specifically including the following steps:

1) Determine the operating conditions of the photovoltaic cell array, whether the photovoltaic cell array is operating normally, and determine the execution steps;

2) The photovoltaic cell array is operating normally, and the maximum power of the photovoltaic cell array is tracked;

3) Determine whether the photovoltaic energy is greater than the set value of the load power, if so, perform step 4); otherwise, perform step 7);

4) The photovoltaic cell array supplies power to the load, and judges whether the remaining photovoltaic energy is greater than the energy demand value of the energy storage battery component, if so, perform step 5), otherwise perform step 9);

5) Charge the energy storage battery components, and judge whether the remaining photovoltaic energy is greater than the grid-connected power threshold, if so, perform step 6); otherwise, perform step 14);

6) Photovoltaic grid-connected power generation, and perform step 14);

7) Determine whether the photovoltaic energy is greater than the energy demand value of the energy storage battery component, if so, perform step 8, otherwise perform step 10) and step 11);

8) The energy storage battery components are charged, and the grid supplies power to the load;

9) Determine whether the remaining photovoltaic energy is greater than the grid-connected power threshold, if so, perform step 6); otherwise, perform step 14);

10) Determine whether the photovoltaic energy is greater than the grid-connected power threshold, if so, perform step 6); otherwise, perform step 14);

11) Determine whether the energy of the energy storage battery is greater than the set value of the load power, if so, perform step 12); otherwise, perform step 13);

12) Discharge the battery pack, supply power to the load, and execute step 14);

13) The grid charges the battery components and supplies power to the load;

14) Determine whether to stop, if so, stop running, if not, go to step 3).

The beneficial effect of the present invention is that: the distributed photovoltaic energy storage system and its working method of the present invention can complete functions such as maximum power tracking MPPT of photovoltaic cell arrays, charge and discharge control of battery energy storage components, and autonomous switching of on-grid/off-grid power generation; Monitoring the operation of the photovoltaic cell array can reasonably control its DC output and maximize the utilization of solar energy; it can monitor the operation of the energy storage battery component and manage the energy of the energy storage battery component through reasonable charge and discharge control , prolong the life of energy storage battery components; realize the optimal coordinated control of two distributed power sources of photovoltaic cell arrays and energy storage battery components, which can improve the quality of system output power, enhance system stability, and improve the overall performance of photovoltaic power generation systems; applicable For low-to-medium power level photovoltaic on-grid/off-grid power generation systems, fully combine photovoltaic power generation and energy storage technologies to realize intelligent control of photovoltaic and energy storage, effectively improve system power generation efficiency and reduce losses.

Description of drawings

Fig. 1 is a block diagram of the overall structure of the distributed photovoltaic energy storage system of the present invention;

Fig. 2 is a connection diagram of the distributed photovoltaic energy storage system of the present invention;

Fig. 3 is a connection structure diagram of the distributed power supply medium via the power conversion module of the present invention;

Fig. 4 is a flow chart of the working method of the distributed photovoltaic energy storage system of the present invention.

Detailed ways

As shown in the overall structural block diagram in Figure 1 and the system connection diagram in Figure 2, the distributed photovoltaic energy storage system includes a distributed power supply medium module, a DC conversion module, a rectification conversion module, a grid-connected inverter module, an off-grid inverter module, and an energy management system; The distributed power medium module includes a photovoltaic cell array and an energy storage battery component; the output of the photovoltaic cell array is connected to the DC conversion module, and the output of the DC conversion module is respectively connected to the grid-connected inverter module, the off-grid inverter module and the energy storage battery component; the rectifier The input end of the conversion module is connected to the grid, the output end of the rectification conversion module is connected to the energy storage battery assembly; the input end of the grid-connected inverter module is connected to the output end of the DC conversion module, and the output end of the grid-connected inverter module is connected to the grid; the DC conversion module The output end of the energy storage battery component is connected to the input end of the off-grid inverter module, and the output end of the off-grid inverter module is connected to the load; the energy management system is connected to the energy storage medium module, DC conversion module, rectification conversion module, and grid-connected inverter module respectively. Connect with the off-grid inverter module.

A photovoltaic battery management system is installed in the photovoltaic cell array, and an energy storage battery management system is installed in the energy storage battery module.

As shown in Figure 3, the connection structure diagram of the distributed power supply medium through the power conversion module, the photovoltaic battery management system, the energy storage battery management system, the DC conversion module, the rectification conversion module, the grid-connected inverter module, the off-grid inverter module and the described Energy management systems are bidirectionally connected through energy state communication lines.

The grid-connected inverter module, the off-grid inverter module, the DC conversion module, the rectification conversion module and the photovoltaic cell array and energy storage battery components are connected through a DC bus.

The grid-connected inverter module, the off-grid inverter module, and the rectification conversion module are connected to the grid and loads through an AC bus.

Photovoltaic cell arrays are composed of crystalline silicon solar cell modules connected in series or in parallel. The grid-connected inverter module includes a grid-connected inverter and a grid-connected protection circuit. The off-grid inverter module includes an off-grid inverter and an off-grid protection circuit.

The system controls the output of the energy storage battery while ensuring the maximum power output of the photovoltaic array, completes the charge and discharge management of the energy storage battery according to a reasonable charge and discharge control strategy, and ensures the power quality of the system on the basis of meeting the energy storage energy regulation. Extend the service life of the energy storage battery.

The system control functions are divided into: optimal coordination control of energy management system, maximum power tracking of photovoltaic cell array, charge and discharge control of energy storage battery components. Among them, the energy management system mainly realizes communication scheduling, system status detection, and optimal power distribution control; photovoltaic array power tracking realizes the maximum power output of photovoltaic array; energy storage battery component charge and discharge control is based on control instructions and reasonable charge and discharge strategies to realize storage Energy input and output of battery components.

The flow chart of the working method of the distributed photovoltaic energy storage system shown in Figure 4 includes the following steps:

1): Determine the operating conditions of the photovoltaic cell array. Is the photovoltaic cell array operating normally? determine the steps to be taken;

2): The photovoltaic cell array is operating normally, and the maximum power tracking of the photovoltaic cell array is performed;

3): Determine whether the photovoltaic energy is greater than the set value of the load power, if so, perform step 4); otherwise, perform step 7);

4): The photovoltaic cell array supplies power to the load, and judges whether the remaining photovoltaic energy is greater than the energy demand value of the energy storage battery component. If so, perform step 5), otherwise perform step 9);

5): Charging the energy storage battery components, and judging whether the remaining photovoltaic energy is greater than the grid-connected power threshold, if so, perform step 6); otherwise, perform step 14);

6): Photovoltaic grid-connected power generation, and perform step 14);

7): Determine whether the photovoltaic energy is greater than the energy demand value of the energy storage battery component, if so, perform step 8, otherwise perform step 10) and step 11);

8): The energy storage battery components are charged, and the grid supplies power to the load;

9): Determine whether the remaining photovoltaic energy is greater than the grid-connected power threshold, if so, perform step 6); otherwise, perform step 14);

10): Determine whether the photovoltaic energy is greater than the grid-connected power threshold, if so, perform step 6); otherwise, perform step 14);

11): Determine whether the energy of the energy storage battery is greater than the set value of the load power, if so, perform step 12), if not, perform step 13);

12): Discharge the battery pack, supply power to the load, and execute step 14);

13): The grid charges the battery components and supplies power to the load;

14): Judging whether to stop, if so, stop running, if not, go to step 3).

According to the scheduling instructions of the energy management system, the system gives priority to sending the power of the photovoltaic cell array to the load bus; if the power is insufficient at this time, the power of the photovoltaic cell array is controlled to be sent to the energy storage battery component, and the power supply is supplied to the load by the grid; When it is full, the energy of the energy storage battery components is controlled to flow into the load bus, and the power of the photovoltaic cell array is sent to the grid bus. If the photovoltaic cell array has no power output and the energy storage battery has no energy output, the grid will charge the energy storage battery and supply power to the load. Through the coordinated control of photovoltaic cell arrays and energy storage battery components, the utilization rate of solar energy can be maximized, the service life of energy storage battery components can be extended, the quality of system output power can be improved, and system stability can be enhanced, thereby improving the overall performance of the photovoltaic power generation system.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be The specific implementation of the invention is modified or equivalently replaced, and any modification or equivalently replaced without departing from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims (7)

1. a distributed photovoltaic energy-storage system is characterized in that, comprises distributed power source medium module, DC converting module, rectifying conversion module, parallel network reverse module, from net inversion module and EMS; The distributed power source medium module comprises photovoltaic battery array and energy-storage battery assembly; Photovoltaic battery array output connects the DC converting module, and DC converting module output is respectively with the parallel network reverse module, be connected with the energy-storage battery assembly from the net inversion module; The input of rectifying conversion module is connected with electrical network, and the rectifying conversion module output is connected with the energy-storage battery assembly; The parallel network reverse module input is connected with DC converting module output, and parallel network reverse module output is connected with electrical network; DC converting module and energy-storage battery assembly output termination are connected with load from net inversion module output from net inversion module input; EMS is respectively with energy-accumulating medium module, DC converting module, rectifying conversion module, parallel network reverse module be connected from the net inversion module.

2. according to the described distributed photovoltaic energy-storage system of claim 1, it is characterized in that, described photovoltaic cell management system, energy-storage battery management system, DC converting module, rectifying conversion module, parallel network reverse module, be connected by order wire is two-way between net inversion module and the described EMS.

3. according to the described distributed photovoltaic energy-storage system of claim 1, it is characterized in that, described parallel network reverse module, be connected by dc bus between net inversion module, DC converting module, rectifying conversion module and photovoltaic battery array, the energy-storage battery assembly.

4. according to the described distributed photovoltaic energy-storage system of claim 1, it is characterized in that, described parallel network reverse module, be connected by ac bus between net inversion module, rectifying conversion module and electrical network, the load.

5. according to the described distributed photovoltaic energy-storage system of claim 1, it is characterized in that described photovoltaic battery array is by the crystal silicon solar battery component string or composes in parallel.

6. according to the described distributed photovoltaic energy-storage system of claim 1, it is characterized in that described parallel network reverse module comprises combining inverter and the protective circuit that is incorporated into the power networks, and comprises from the net inverter with from the net protective circuit from the net inversion module.

7. distributed photovoltaic energy-storage system method of work, comprise the distributed photovoltaic energy-storage system, from being provided with the photovoltaic cell management system, be provided with the energy-storage battery management system in the energy-storage battery assembly certainly in the photovoltaic battery array, it is characterized in that, specifically comprise the steps:

1) judge the photovoltaic battery array service conditions, the photovoltaic battery array operation is normal, determines execution in step;

2) the photovoltaic battery array operation is normal, carries out the photovoltaic battery array maximum power tracing;

3) whether judge photovoltaic energy greater than the bearing power set point, if execution in step 4 then), execution in step 7 then if not);

4) photovoltaic battery array powers to the load, and whether judges the residue photovoltaic energy greater than energy-storage battery assembly energy requirement value, if execution in step 5 then), execution in step 9 then if not);

5) if energy-storage battery assembly charging, and whether judge the residue photovoltaic energy greater than the power threshold that is incorporated into the power networks is execution in step 6 then), execution in step 14 then if not);

6) parallel network power generation, and execution in step 14);

7) whether judge photovoltaic energy greater than energy-storage battery assembly energy requirement value, if execution in step 8 then, execution in step 10 then if not) and step 11);

8) energy-storage battery assembly charging, electrical network powers to the load;

9) whether judge the residue photovoltaic energy greater than the power threshold that is incorporated into the power networks, if execution in step 6 then), execution in step 14 then if not);

10) whether judge photovoltaic energy greater than the power threshold that is incorporated into the power networks, if execution in step 6 then), execution in step 14 then if not);

11) whether judge the energy-storage battery energy greater than the bearing power set point, if execution in step 12 then), execution in step 13 then if not);

12) battery component discharge powers to the load, and execution in step 14);

13) electrical network charges to battery component, and powers to the load;

14) judge whether to shut down, if then out of service, execution in step 3 then if not).

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