CN202817835U - Intelligent micro-grid system based on photovoltaic power generation - Google Patents

Abstract

The utility model discloses an intelligent micro-grid device based on photovoltaic power generation, which includes a BUCK converter and a digital signal controller; there are multiple BUCK converters, which are interleaved and connected in parallel; the output end of the digital signal controller is connected with the BUCK converter . The smart microgrid device based on photovoltaic power generation of the utility model can effectively and stably realize the automatic switching of the maximum power point tracking control mode and the constant voltage and constant current charging control mode of the storage battery, and has a simple structure and convenient operation.

Description

A smart microgrid device based on photovoltaic power generation

technical field

The utility model relates to a smart micro-grid device based on photovoltaic power generation, in particular to a smart micro-grid device using interleaved parallel technology.

Background technique

Photovoltaic cells are a direct power generation method that converts light energy into electrical energy through semiconductor devices. It has many advantages, but there are also some disadvantages. Because photovoltaic cells are affected by light and temperature, their power generation will vary greatly, and batteries are usually required. Waiting for energy storage devices to store energy to supply power to loads; due to the low conversion efficiency of photovoltaic cells, in order to improve the efficiency of photovoltaic cells, new photovoltaic panels can be used to improve efficiency, and maximum power point tracking technology can also be used to improve efficiency. In the actual photovoltaic power generation system, the maximum power point tracking control is necessary.

The structural diagram of the existing photovoltaic power generation system is shown in FIG. 4 , which includes a photovoltaic cell, a DC/DC converter, a controller and a DC load, or may also include a storage battery.

At the same time, the battery is used as an energy storage device, which stores the electric energy of the photovoltaic cell to provide energy for the load; the charging control module plays a vital role in this system, it not only realizes the charging control of the battery, but also realizes the control of the battery. The maximum power point tracking control of photovoltaic cells, therefore, how to coordinate the maximum power point tracking control, constant voltage and constant current charging mode control has become a key technical problem to be solved.

Contents of the invention

The purpose of the utility model is to solve the defects in the prior art and provide an intelligent micro-grid device capable of effectively coordinating maximum power point control, constant voltage and constant current charging mode control.

In order to achieve the above purpose, the utility model provides a smart microgrid device based on photovoltaic power generation, including a BUCK converter and a digital signal controller; there are multiple BUCK converters, which are interleaved and connected in parallel; the output terminal of the digital signal controller Connect with BUCK converter.

There are three BUCK converters, and the duty cycle of the driving signal of each converter is equal, and the phase difference between them is 120°. The smart microgrid device also includes an RS-485 communication interface and a human-computer interaction interface; the human-computer interaction interface is connected to the input terminal of the digital signal controller through the RS-485 interface. The digital signal controller adopts dsPIC30F2020 one-chip computer. The power tube of the BUCK converter is an Infineon IGBT module of model FF200R12KT4.

Compared with the prior art, the utility model has the following advantages: the topology structure of BUCK converters in interleaved parallel connection can not only realize the maximum power point tracking control of photovoltaic cells, but also realize the automatic constant voltage and constant current charging control of batteries. At the same time, the digital control of the system is realized through the digital signal controller, and the automatic and smooth switching of the maximum power tracking, constant voltage and constant current working modes is realized. The use of interleaved parallel technology can effectively reduce the size of the inductor, greatly reduce the ripple of the total output current, improve the accuracy of the output voltage and reduce the filter capacitor. In addition, the current stress of the power switch tube is reduced, which is conducive to the selection of the device. At the same time, remote control can be carried out through the human-computer interaction interface and RS-485 interface.

Description of drawings

Fig. 1 is a circuit structure diagram of a three-phase interleaved parallel buck converter of the present invention.

Fig. 2 is an interleaved parallel circuit diagram of the BUCK converter in Fig. 1;

Fig. 3 is a schematic diagram of the three-phase interleaved parallel connection of the BUCK converter in Fig. 2 .

Figure 4 is a structural diagram of a photovoltaic power generation system.

Detailed ways

The following is a detailed description of the smart micro-grid device of the present invention in conjunction with the accompanying drawings.

Referring to Fig. 1, the smart microgrid device based on photovoltaic power generation of the present invention includes a three-phase interleaved parallel buck converter, a digital signal controller, an RS-485 interface and a human-computer interaction interface, and the input of the three-phase interleaved parallel buck converter The terminal and the output terminal are respectively connected with the photovoltaic cell and the storage battery. The digital controller is respectively connected with the photovoltaic cell and the storage battery. Combined with Figure 2, the circuit structure is composed of three independent BUCK circuits with input and output connected in parallel. The duty ratios of the driving signals of the three power tubes are equal, and the phases are staggered by 120°. Power tubes Q1, Q2, and Q3 use Infineon's IGBT, model FF200R12KT4; each inductance is 60uH. Combined with Figure 3, through the three-phase interleaved parallel BUCK converter, the input and output currents are reduced equally, and the current stress of the inductor (L1, L2, and L3) and the power device (Q1, Q2, Q3) is reduced, which can effectively reduce the output current ripple.

The digital signal controller uses dsPIC30F2020 single-chip microcomputer, the input voltage range is 100-150VDC; the output voltage is 48-60VDC, and the output power is 10kW. The automatic switching of the working mode of the system is carried out by means of digital control. There are three working modes of the system: maximum power point tracking control mode, constant voltage charging mode and constant current charging mode. The maximum power point tracking control is realized by the disturbance and observation method with variable parameters, that is, a larger tracking step is used at a position far from the maximum power point to speed up the tracking speed; a smaller tracking step is used near the maximum power point , to improve system stability. The constant voltage charging mode is realized by digital PI control, and the constant current charging mode is realized by digital PI control. In the main program, the control algorithms of the three working modes are calculated in parallel, that is, in a main cycle, it is necessary to execute the calculation of the MPPT control algorithm, the constant voltage charging PI control algorithm and the constant current charging PI control algorithm. By comparing various algorithms Calculate the size of the duty cycle result to determine the working mode to be executed, that is, take the control algorithm with the calculated minimum value of the duty cycle as the system working mode, and then realize automatic switching of various working modes.

At the same time, the human-computer interaction interface and RS-485 interface can be used for remote operation, and the digital signal controller can be controlled to switch the working mode.

The smart microgrid device based on photovoltaic power generation of the utility model can effectively and stably realize the automatic switching of the maximum power point tracking control mode, the constant voltage and constant current charging control mode of the battery, and has a simple structure and convenient operation.

Claims (5)

1. intelligent micro-grid device based on photovoltaic generation, it is characterized in that: this device comprises BUCK converter and digital signal controller; Described BUCK converter is a plurality of, and interlaced parallel connection; The output of described digital signal controller links to each other with described BUCK converter.

2. intelligent micro-grid device according to claim 1, it is characterized in that: described BUCK converter is 3, the driving signal dutyfactor equal and opposite in direction of each converter, and phase difference is 120 ° each other.

3. intelligent micro-grid device according to claim 2, it is characterized in that: described intelligent micro-grid device also comprises RS-485 communication interface and human-computer interaction interface; Described human-computer interaction interface links to each other with the input of described digital signal controller by described RS-485 interface.

4. according to claim 1 to 3 arbitrary described intelligent micro-grid devices, it is characterized in that: described digital signal controller adopts the dsPIC30F2020 single-chip microcomputer.

5. according to claim 1 to 3 arbitrary described intelligent micro-grid devices, it is characterized in that: it is the IGBT of the Infineon module of FF200R12KT4 that the power tube of described BUCK converter is selected model.

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