CN202616801U - Photovoltaic/ storage-battery hybrid distribution-type power generation system based on current inverter - Google Patents

Abstract

The utility model discloses a photovoltaic/storage-battery hybrid distribution-type power generation system based on a current inverter. The photovoltaic/storage-battery hybrid distribution-type power generation system based on the current inverter includes a first voltage/current transformer or a second voltage/current transformer and a third voltage/current transformer, a storage battery, a bidirectional power boosting DC/DC converter connected with the storage battery, a photovoltaic battery panel, a unidirectional power boosting DC/DC converter connected with an output terminal of the photovoltaic battery panel, and a current-type grid-connected inverter. In one embodiment, the bidirectional power boosting DC/DC converter and the unidirectional power boosting DC/DC converter are connected with the current-type grid-connected inverter through the first voltage/current transformer. In another embodiment, the bidirectional power boosting DC/DC converter and the unidirectional power boosting DC/DC converter are connected with the current-type grid-connected inverter through the second voltage/current transformer and the third voltage/current transformer respectively. Since the photovoltaic/storage-battery hybrid distribution-type power generation system based on the current inverter provided by the utility model is based on the current-type grid-connected inverter, the photovoltaic/storage-battery hybrid distribution-type power generation system based on the current inverter has advantages of the current-type grid-connected inverter. Since a photovoltaic system and a storage battery system share the current-type grid-connected inverter, the cost is reduced.

Description

A Photovoltaic/Battery Hybrid Distributed Power Generation System Based on Current Inverter

technical field

The utility model relates to a power generation system, in particular to a photovoltaic/storage battery hybrid distributed power generation system based on a current inverter, and belongs to the technical fields of electrician, power electronics and new energy power generation.

Background technique

At present, there are two main types of high-power grid-connected inverters: voltage source type and current source type. Due to the constant DC bus voltage, direct AC voltage control, and the widespread use of switching devices in voltage source converters, most current research on inverter-type distributed generation is based on voltage source inverters. Compared with voltage inversion power generation, current inversion distributed power generation has its own characteristics: (1) The topology is simple. (2) The output voltage waveform of the inverter is good, and the dv/dt is small. (3) The inverter PWM strategy is simple. (4) Strong short-circuit current protection capability. When a short-circuit fault occurs in the power grid, the inductance on the DC side of the inverter has a good current limiting effect. (5) Since the output waveform is close to a sine wave, the grid-connected cable length of the inverter is allowed to be longer. (6) The current source inverter itself has a boost function. The output of renewable energy (such as photovoltaic cells) can be directly connected to the grid through the inverter, without the need for a DC/DC boost converter. (7) Part of the DC bus inductance can be realized by using the inductance effect of the cable, and the DC bus inductance has a long life. (8) The dynamic performance of current inverter distributed power generation can fully meet the power change requirements of wind power, photovoltaic and other renewable energy sources.

At present, most photovoltaic grid-connected power generation systems at home and abroad are based on voltage source inverters, while current inverter-type grid-connected power generation systems are rare; and battery charging and discharging systems based on current-source inverters are also very few.

Due to the intermittent characteristics of the output power of renewable energy generation systems such as photovoltaics, the unstable factors brought to the transmission grid limit the large-scale grid connection based on distributed generation of renewable energy. Therefore, in practice, energy storage systems such as battery systems are required to participate in the smoothing of output power to compensate for the unstable output power of renewable energy. On the other hand, when the main grid is overhauled or fails, the distributed generation based on renewable energy will be disconnected from the main grid and form an island grid together with the local load. At this time, the distributed generation needs to provide energy for the local load in the island grid . However, due to the unstable output power of distributed power generation based on renewable energy, it cannot balance with the local power load in the island grid. Therefore, it is necessary to use the energy storage system to fill the gap between the output power of the distributed power generation system and the local power load in the island grid. power difference between them.

Traditional photovoltaic and battery systems are connected on the grid side through their own grid-connected inverters, which requires at least two sets of grid-connected inverters, which increases the cost of the system.

Utility model content

Aiming at the deficiencies in the existing technology, the purpose of this utility model is to provide a photovoltaic/battery hybrid distributed power generation system based on a current inverter that can reduce costs and has the advantages of a current-mode grid-connected inverter. The unstable power output of photovoltaic panels, and the ability to support the grid voltage under the island grid.

In order to achieve the above object, the utility model is realized through the following technical solutions:

The utility model comprises a first voltage/current converter or a second voltage/current converter and a third voltage/current converter connected in series, both of which are used to convert voltage into current; a storage battery; a bidirectional power step-up DC/DC converter , connected to the battery, used to charge and discharge the battery; photovoltaic panels; unidirectional power step-up DC/DC converter, connected to the output of the photovoltaic panels, used to transmit the energy emitted by the photovoltaic panels to the second a voltage/current converter or a third voltage/current converter; and a current-type grid-connected inverter connected to the input terminal of the grid for connecting the first voltage/current converter or the second voltage/current converter and The DC current output by the third voltage/current converter is converted into AC current; the output ends of the bidirectional power boosting DC/DC converter and the unidirectional power boosting DC/DC converter pass through the first voltage/current converter and the current type The input terminals of the grid-connected inverter are connected, or the output terminals of the bidirectional power boost DC/DC converter and the unidirectional power boost DC/DC converter pass through the second voltage/current converter and the third voltage/current converter respectively Connect with the input end of the current source grid-connected inverter.

Capacitors are connected in parallel at both output ends of the storage battery, the photovoltaic battery panel, the bidirectional power boost DC/DC converter and the unidirectional power boost DC/DC converter to reduce voltage ripple.

The above-mentioned current-source grid-connected inverter is connected to the grid through an inductor, and is used to reduce grid-connected current harmonics and realize grid-connected current control.

The above system structure is general and applicable to the integration of other renewable energy and energy storage systems. Among them, photovoltaic panels can be replaced by fuel cells, and batteries can be replaced by supercapacitors.

The photovoltaic/battery system proposed by the utility model is based on a current-type grid-connected inverter, so it has a current-inversion type distributed power generation with a simple topological structure, strong fault current protection capability, boosting function, and long life of the inductance of the energy storage device on the DC side. Long and other advantages; the photovoltaic system and the battery system of the utility model share a current-type grid-connected inverter, which saves costs, and the control is direct and simple; the utility model effectively integrates the battery and the photovoltaic system on the DC side, not only smooth The unstable power output of photovoltaic panels also enables the system to have the ability to support the grid voltage under the island grid; when a short-circuit fault occurs in the grid, the energy in the photovoltaic can be effectively stored in the battery, avoiding the overcurrent of grid-connected current.

Description of drawings

Fig. 1 is a schematic structural diagram of a photovoltaic/battery parallel hybrid distributed power generation system based on a current inverter proposed by the present invention;

Fig. 2 is a schematic structural diagram of a photovoltaic/battery series hybrid distributed power generation system based on a current inverter proposed by the present invention;

Fig. 3 is a schematic diagram of a specific embodiment of a photovoltaic/battery hybrid distributed power generation system based on a current inverter proposed by the present invention.

Each label in the figure: battery 1, bidirectional power boost DC/DC converter 2, photovoltaic panel 3, unidirectional power boost DC/DC converter 4, first voltage/current converter 5-1, second voltage /current converter 5-2, third voltage/current converter 5-3, current-type grid-connected inverter 6, power grid 7, current-inversion photovoltaic power generation system 8, nonlinear load 9, current-based inverter The photovoltaic/battery parallel hybrid distributed power generation system 10, the current inverter wind power generation system 11, the photovoltaic/battery series hybrid distributed power generation system based on the current inverter 12, the first linear load 13, and the first circuit breaker 14 , the second circuit breaker 15 , and the second linear load 16 .

Detailed ways

In order to make the technical means, creative features, goals and effects achieved by the utility model easy to understand, the utility model will be further elaborated below in conjunction with specific embodiments.

The utility model proposes two specific structures: the first is a photovoltaic/battery parallel hybrid distributed power generation system 10 based on a current inverter, and the second is a photovoltaic/battery series hybrid distributed power generation system based on a current inverter System 12.

Among them, the photovoltaic/battery parallel hybrid distributed power generation system 10 based on current inverter includes a first voltage/current converter 5-1, a battery 1, and a bidirectional power step-up DC/DC converter 2 connected to the battery 1 , a photovoltaic panel 3, a unidirectional power step-up DC/DC converter 4 connected to the output terminal of the photovoltaic panel 3 and a current source grid-connected inverter 6 connected to the input terminal of the power grid 7; a bidirectional power step-up DC Both the output terminals of the DC/DC converter 2 and the unidirectional power boost DC/DC converter 4 are connected to the input terminals of the current source grid-connected inverter 6 through the first voltage/current converter 5-1.

In this system, the photovoltaic system is connected in parallel at the DC voltage bus through a unidirectional power boost DC/DC converter 4 and the battery system is connected through a bidirectional power boost DC/DC converter 2, and the DC voltage bus is connected through a common first voltage The current converter 5 - 1 is connected to the DC current bus, and the DC current bus is connected to the grid 7 through the current-type grid-connected inverter 6 .

Referring to FIG. 1 , a battery 1 is connected to a first voltage/current converter 5 - 1 through a bidirectional power boost DC/DC converter 2 , and the bidirectional power boost DC/DC converter 2 is used to charge and discharge the battery 1 . The photovoltaic cell panel 3 is connected to the first voltage/current converter 5-1 through the unidirectional power step-up DC/DC converter 4, and is used to transmit the energy emitted by the photovoltaic cell panel 3 to the first voltage/current converter 5 -1. The unidirectional power boost DC/DC converter 4 and the bidirectional power boost DC/DC converter 2 are connected in parallel at the output side. The first voltage/current converter 5-1 converts the output voltage of the bidirectional power step-up DC/DC converter 2 and the unidirectional power step-up DC/DC converter 4 into current, and converts it with the current-type grid-connected inverter 6 connect. The current-source grid-connected inverter 6 converts the DC current into an AC grid-connected current, which is connected to the grid 7 .

Among them, the photovoltaic/battery series hybrid distributed power generation system 12 based on the current inverter includes the second voltage/current converter 5-2 and the third voltage/current converter 5-3, the storage battery 1, and the storage battery 1 The connected bidirectional power step-up DC/DC converter 2, the photovoltaic panel 3, the unidirectional power step-up DC/DC converter 4 connected to the output terminal of the photovoltaic panel 3 and the current connected to the input terminal of the grid 7 type grid-connected inverter 6; the output ends of the bidirectional power boost DC/DC converter 2 and the unidirectional power boost DC/DC converter 4 pass through the second voltage/current converter 5-2 and the third voltage/current respectively The converter 5-3 is connected to the input end of the current source grid-connected inverter 6 .

In this system, the photovoltaic system and the storage battery system respectively pass independent voltage/current converters (second voltage/current converter 5-2, third voltage/current converter 5-3) and common current-type grid-connected inverters. The device 6 DC current bus is connected. In this way, the voltage/current converters of the photovoltaic system and the battery system will form a series connection at the DC current bus.

Referring to FIG. 2 , the battery 1 is connected to a second voltage/current converter 5 - 2 through a bidirectional power boost DC/DC converter 2 , and the bidirectional power boost DC/DC converter 2 is used to charge and discharge the battery 1 . The photovoltaic cell panel 3 is connected with the third voltage/current converter 5-3 through the unidirectional power step-up DC/DC converter 4, and transmits the energy emitted by the photovoltaic cell panel 3 to the third voltage/current converter 5-3 . The second voltage/current converter 5-2 converts the output voltage of the bidirectional power step-up DC/DC converter 2 into current, and the third voltage/current converter 5-3 converts the unidirectional power step-up DC/DC converter 4 The output voltage is converted into current. The output of the second voltage/current converter 5-2 is connected in series with the output of the third voltage/current converter 5-3, and is connected with the DC bus of the current source grid-connected inverter 6 . The current-source grid-connected inverter 6 converts the DC current into an AC grid-connected current, which is connected to the grid 7 .

In the current inverter-based photovoltaic/battery parallel hybrid distributed power generation system 10 and the current inverter-based photovoltaic/battery series hybrid distributed power generation system 12, the battery 1, the photovoltaic panel 3, and the bidirectional power boost Capacitors are connected in parallel at the two output ends of the DC/DC converter 2 and the unidirectional power step-up DC/DC converter 4; the current mode grid-connected inverter 6 is connected to the grid 7 through an inductor; the photovoltaic panel 3 can be powered by a fuel cell Instead, the accumulator 1 can be replaced by a supercapacitor. And both systems can be expanded into multiple photovoltaic channels composed of photovoltaic panels 3 and unidirectional power boost DC/DC converters 4 and multiple channels composed of batteries 1 and bidirectional power boost DC/DC converters 2 Battery channel composition.

Bidirectional power boost DC/DC converter 2 mentioned in the utility model, unidirectional power boost DC/DC converter 4, first voltage/current converter 5-1, second voltage/current converter 5- 2. Both the third voltage/current converter 5-3 and the current-source grid-connected inverter 6 are existing devices, and will not be repeated here.

Referring to Fig. 3, a current inverter photovoltaic power generation system 8, a photovoltaic/battery parallel hybrid distributed power generation system 10 based on a current inverter, a current inverter wind power generation system 11, a photovoltaic/battery series connection based on a current inverter The hybrid distributed generation system 12 is connected in parallel on the grid 7 side, and the grid 7 is also connected with a nonlinear load 9 , a first linear load 13 and a second linear load 16 .

When both the first circuit breaker 14 and the second circuit breaker 15 are closed, all the systems in Fig. 3 are connected to the grid. Current inverter photovoltaic power generation system 8, photovoltaic/battery parallel hybrid distributed power generation system based on current inverter 10, current inverter wind power generation system 11, photovoltaic/battery series hybrid distributed power generation system based on current inverter The AC side of the power generation system 12 outputs active power, and the reactive power is controlled by respective grid-connected inverters.

When the first circuit breaker 14 is disconnected, the current inverter photovoltaic power generation system 8, the nonlinear load 9, the photovoltaic/storage battery parallel hybrid distributed power generation system 10 based on the current inverter, and the current inverter photovoltaic power generation system 10 in Fig. 3 The wind power generation system 11 , the photovoltaic/battery series hybrid distributed power generation system 12 based on the current inverter, and the second linear load 16 form an island grid. At this time, the current inverter-based photovoltaic/battery parallel hybrid distributed power generation system 10 and the current inverter-based photovoltaic/battery series hybrid distributed power generation system 12 will realize corresponding output voltage control and coordinate control. Since these two current inverter-based photovoltaic/battery hybrid distributed generation system structures can both inject power into the grid and absorb power from the grid, they can compensate for differences between power generation and power loads in island grids , can be used to support the voltage of the island grid.

The basic principles and main features of the present utility model and the advantages of the present utility model have been shown and described above. Those skilled in the art should understand that the utility model is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model The new model also has various changes and improvements, and these changes and improvements all fall within the scope of the claimed utility model. The scope of protection required by the utility model is defined by the appended claims and their equivalents.

Claims (4)

1. the photovoltaic based on current inverter/storage battery hybrid distributed formula electricity generation system is characterized in that, comprises

The second voltage/current converter (5-2) of the first voltage/current converter (5-1) or series connection and tertiary voltage/power pack (5-3) all are used for voltage transitions is become electric current;

Storage battery (1);

Bidirectional power voltage boosting dc/DC converter (2) is connected with storage battery (1), is used for storage battery (1) is discharged and recharged;

Photovoltaic battery panel (3);

Unidirectional power voltage boosting dc/DC converter (4) is connected with photovoltaic battery panel (3) output, is used for sending the energy that photovoltaic battery panel (3) sends to the first voltage/current converter (5-1) or tertiary voltage/power pack (5-3);

With current mode combining inverter (6), be connected with electrical network (7) input, be used for converting the direct current of the first voltage/current converter (5-1) or the second voltage/current converter (5-2) and tertiary voltage/power pack (5-3) output to alternating current;

Said bidirectional power voltage boosting dc/DC converter (2) all is connected with current mode combining inverter (6) input through the first voltage/current converter (5-1) with unidirectional power voltage boosting dc/DC converter (4) output, or said bidirectional power voltage boosting dc/DC converter (2) is connected with current mode combining inverter (6) input with tertiary voltage/power pack (5-3) through the second voltage/current converter (5-2) respectively with unidirectional power voltage boosting dc/DC converter (4) output.

2. the photovoltaic based on current inverter according to claim 1/storage battery hybrid distributed formula electricity generation system is characterized in that,

Two outputs of said storage battery (1), photovoltaic battery panel (3), bidirectional power voltage boosting dc/DC converter (2) and unidirectional power voltage boosting dc/DC converter (4) all are parallel with electric capacity.

3. the photovoltaic based on current inverter according to claim 1/storage battery hybrid distributed formula electricity generation system is characterized in that,

Said current mode combining inverter (6) is connected with electrical network (7) through inductance.

4. according to any described photovoltaic of claim 1 to 3/storage battery hybrid distributed formula electricity generation system, it is characterized in that based on current inverter,

Said photovoltaic battery panel (3) can be replaced by fuel cell, and said storage battery (1) can be replaced by super capacitor.

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