CN110535173B - Alternating current-direct current hybrid photovoltaic power generation energy storage system - Google Patents
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- Y02E10/00—Energy generation through renewable energy sources
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Abstract
The invention provides an alternating current-direct current hybrid photovoltaic power generation energy storage system, wherein an energy storage converter formed by a plurality of energy storage high-voltage isolation type DC/DC converters is connected to a direct current power grid in series, and each energy storage high-voltage isolation type DC/DC converter adopts a structure that the output is connected in series and the input is connected in parallel; by the structure, the path for charging the energy storage device from the photovoltaic assembly side is adjusted to be as follows: the photovoltaic module generates power, the power passes through the photovoltaic high-voltage isolation type DC/DC converter and then passes through the energy storage high-voltage isolation type DC/DC converter to charge the energy storage device, and the two stages are total; and the path of discharge from the energy storage device is: the energy storage device discharges electricity to a power grid through the energy storage high-voltage isolation type DC/DC converter and the cascade module, and the two stages are achieved in total. Therefore, in the energy storage conversion process under the structure, part of charging and discharging paths only need to pass through four stages, so that the overall conversion efficiency is improved compared with the prior art.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to an alternating current-direct current hybrid photovoltaic power generation energy storage system.
Background
Large-scale energy storage has been applied to power systems gradually at present, and can be used for frequency modulation and voltage regulation of systems, power smoothing of photovoltaic power generation systems, and storage of daytime energy of photovoltaic power generation systems to achieve power generation at night. However, in the existing technical scheme of the medium-high voltage alternating current and direct current hybrid photovoltaic power generation system, an energy storage system is not provided, or the energy storage system adopts a mode of being positioned on the medium-high voltage alternating current power grid side.
For an alternating current-direct current hybrid photovoltaic power generation energy storage system positioned on the side of an alternating current power grid, the alternating current-direct current hybrid photovoltaic power generation energy storage system is generally of a two-stage structure, namely, a structure of a low-voltage energy storage inverter and a power booster transformer is adopted, or a structure of a cascade H bridge and an isolated DC/DC converter is adopted. In such systems, the charging path from the photovoltaic module side is: the photovoltaic module generates power energy, the power energy passes through the two-stage converter from direct current to alternating current and then passes through the two-stage structure of the energy storage system to charge the battery, and four stages are achieved in total; the path of discharge from the energy storage battery is: the battery discharges to the grid through the two-stage structure of the energy storage system, for a total of two stages.
Thus, such systems suffer from an overall low conversion efficiency due to the partial charge and discharge paths required to pass through six stages.
Disclosure of Invention
The invention provides an alternating current-direct current hybrid photovoltaic power generation energy storage system, which aims to solve the problem of low energy storage conversion efficiency in the prior art.
In order to achieve the purpose, the technical scheme provided by the application is as follows:
an alternating current-direct current hybrid photovoltaic power generation energy storage system, comprising: the system comprises a plurality of photovoltaic high-voltage isolated DC/DC converters, a plurality of energy storage high-voltage isolated DC/DC converters, at least one energy storage device, M upper bridge arms, M lower bridge arms, M inductance devices and a filter; wherein:
one end of each upper bridge arm is connected with one end of the corresponding lower bridge arm through one inductance device;
the middle point of each inductance device is connected with an alternating current power grid through the filter;
the other end of each upper bridge arm is connected, and the connecting point is connected with the anode of a direct current power grid;
the other end of each lower bridge arm is connected, and a connecting point is connected with the negative electrode of the direct current power grid;
the upper bridge arm and the lower bridge arm respectively comprise N cascade modules which are connected in series through an alternating current side, and N is a positive integer; the direct current side of the cascade module is suspended;
the photovoltaic conversion units are connected in series through output ends to form photovoltaic converter strings, and at least one photovoltaic converter string is connected between the positive pole and the negative pole of the direct current power grid; the photovoltaic conversion unit includes: the photovoltaic high-voltage isolated DC/DC converter or the photovoltaic high-voltage isolated DC/DC converters with at least two output ends connected in parallel;
the input end of the photovoltaic high-voltage isolation type DC/DC converter is used for connecting a photovoltaic assembly;
the photovoltaic high-voltage isolation type DC/DC converter comprises: the isolation voltage grade between the primary side and the secondary side of the high-frequency transformer is more than or equal to 10 kV;
the energy storage conversion units are connected in series through output ends to form an energy storage converter string, and at least one energy storage converter string is connected between the positive pole and the negative pole of the direct current power grid; the energy storage conversion unit comprises: the energy storage high-voltage isolation type DC/DC converter or the energy storage high-voltage isolation type DC/DC converters with at least two output ends connected in parallel;
the input ends of the energy storage high-voltage isolation type DC/DC converters are connected in parallel with one energy storage device.
Optionally, the input end of each photovoltaic high-voltage isolated DC/DC converter in the photovoltaic converter string is respectively used for connecting a corresponding photovoltaic module; or,
the input ends of the photovoltaic high-voltage isolated DC/DC converters in the photovoltaic converter string are connected in parallel to be connected with the same photovoltaic module; in the alternative to this, either,
in the photovoltaic converter string, a plurality of input ends of the photovoltaic high-voltage isolation type DC/DC converters with the output ends connected in series are connected in parallel to be connected with the same photovoltaic module.
Preferably, the method further comprises the following steps: a plurality of optimizer groups;
the input end of the photovoltaic high-voltage isolation type DC/DC converter is connected with the output end of at least one optimizer group;
the optimizer group comprises at least one optimizer, the output ends of the optimizers are connected in series, the two ends of the optimizer group are connected in series, and the input end of the optimizer is connected with at least one photovoltaic module.
Preferably, the optimizer is configured to implement maximum power point tracking, MPPT, control for the connected photovoltaic module.
Preferably, the method further comprises the following steps: and the combiner box is used for combining the outputs of the connected optimizer groups and outputting the combined direct current electric energy to the corresponding photovoltaic high-voltage isolated DC/DC converter.
Optionally, the input ends of the energy storage high-voltage isolated DC/DC converters in the energy storage converter string are connected in parallel, and the two ends after being connected in parallel are connected with the energy storage device; or,
in the energy storage converter string, the input ends of all the energy storage high-voltage isolation type DC/DC converters in the energy storage conversion units with a plurality of output ends connected in series are connected in parallel, and the two ends after being connected in parallel are connected with the corresponding energy storage devices; in the alternative to this, either,
in the energy storage converter string, the input ends of the energy storage high-voltage isolated DC/DC converters corresponding to the energy storage conversion units are connected in parallel, and the two ends after being connected in parallel are connected with the corresponding energy storage devices; still alternatively, the first and second substrates may be,
in the energy storage converter string, the input ends of the single energy storage high-voltage isolated DC/DC converter corresponding to the energy storage conversion units with the output ends connected in series are connected in parallel, and the two ends after being connected in parallel are connected with the corresponding energy storage devices.
Preferably, the main circuit of the cascade module is a half-bridge topology or a full-bridge topology.
Preferably, the main circuit of the photovoltaic high-voltage isolation type DC/DC converter is any one of an LC series resonance topology, an LLC series resonance topology, a dual-active DC/DC topology, a full-bridge DC/DC topology, a power bidirectional LC series resonance topology, and a power bidirectional LLC series resonance topology.
Preferably, the main circuit of the energy storage high-voltage isolation type DC/DC converter is any one of a dual-active DC/DC topology, a power bidirectional LC series resonance topology and a power bidirectional LLC series resonance topology.
Preferably, the main circuits of the photovoltaic high-voltage isolation type DC/DC converter and the energy storage high-voltage isolation type DC/DC converter are both of a multi-winding single-input multi-output structure, and the output ports are connected in series to obtain the output end of the corresponding main circuit.
Preferably, the energy storage device is: any one of a battery unit, a flywheel energy storage device, a pumped storage energy storage device and a heat energy storage device; or,
the energy storage device includes: the battery unit is connected with the converter, the battery unit is connected with one end of the converter, and the other end of the converter is used for being connected with the energy storage high-voltage isolation type DC/DC converter.
The invention provides an alternating current-direct current hybrid photovoltaic power generation energy storage system.A plurality of energy storage high-voltage isolated DC/DC converters are connected to a direct current power grid in series, and each energy storage high-voltage isolated DC/DC converter adopts a structure that the output is connected in series and the input is connected in parallel; by the structure, the path for charging the energy storage device from the photovoltaic assembly side is adjusted to be as follows: the photovoltaic module generates power, the power passes through the photovoltaic high-voltage isolation type DC/DC converter and then passes through the energy storage high-voltage isolation type DC/DC converter to charge the energy storage device, and the two stages are total; and the path of discharge from the energy storage device is: the energy storage device discharges electricity to a power grid through the energy storage high-voltage isolation type DC/DC converter and the cascade module, and the two stages are achieved in total. Therefore, in the energy storage conversion process under the structure, part of charging and discharging paths only need to pass through four stages, so that the overall conversion efficiency is improved compared with the prior art. In addition, the isolation voltage grade between the primary side and the secondary side of the high-frequency transformer in the photovoltaic high-voltage isolation type DC/DC converter is greater than or equal to 10kV, so that the alternating-current and direct-current hybrid photovoltaic power generation and energy storage system can be used for merging electric energy in the connected photovoltaic modules into a medium-high voltage direct current power grid, and further transmitting the electric energy with smaller loss.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1a to fig. 1d are schematic diagrams of four structures of a main circuit in an ac/dc hybrid photovoltaic power generation energy storage system according to an embodiment of the present invention;
FIGS. 2a to 2b are schematic diagrams of two kinds of circuits of a main circuit in a cascade module according to an embodiment of the present invention;
fig. 3a to 3d are schematic diagrams of four circuits of a main circuit in a photovoltaic high-voltage isolated DC/DC converter according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a main circuit in the photovoltaic high-voltage isolated DC/DC converter and the energy storage high-voltage isolated DC/DC converter provided in the embodiment of the present invention;
fig. 5 is a schematic structural diagram of an energy storage device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The invention provides an alternating current-direct current hybrid photovoltaic power generation energy storage system, which aims to solve the problem of low energy storage conversion efficiency in the prior art.
Referring to fig. 1a to 1d, the ac/dc hybrid photovoltaic power generation and energy storage system includes: the photovoltaic high-voltage isolated DC/DC converters 101, the energy-storage high-voltage isolated DC/DC converters 102, at least one energy storage device, M upper bridge arms 201, M lower bridge arms 202, M inductance devices 103, and a filter 104, where a value of M may be determined according to a specific application environment, for example, any one of values 2 to 6 (fig. 1a to 1d take M ═ 3 as an example), which is not limited herein and is within a protection range of the present application; wherein:
one end of each upper bridge arm 201 is connected with one end of the corresponding lower bridge arm 202 through an inductance device 103;
the middle points of the inductance devices 103 are respectively connected with an alternating current power grid through filters 104;
the other end of each upper bridge arm 201 is connected, and the connecting point is connected with the anode of a direct current power grid;
the other end of each lower bridge arm 202 is connected, and the connecting point is connected with the negative electrode of the direct current power grid;
the upper bridge arm 201 and the lower bridge arm 202 both comprise N cascade modules connected in series through an alternating current side, and N is a positive integer; the direct current side of the cascade module is suspended; and an alternating current bus and a high-voltage direct current bus are respectively formed by modular multilevel cascade modules on the power grid side, so that the whole system can be simultaneously connected with an alternating current power grid and a direct current power grid.
Meanwhile, a plurality of photovoltaic conversion units are connected in series through output ends to form a photovoltaic converter string, and at least one photovoltaic converter string is connected between the positive pole and the negative pole of the direct-current power grid; the photovoltaic conversion unit includes: a photovoltaic high-voltage isolated DC/DC converter 101, or at least two photovoltaic high-voltage isolated DC/DC converters 101 with output terminals connected in parallel;
the input end of the photovoltaic high-voltage isolation type DC/DC converter 101 is used for connecting a photovoltaic module;
the energy storage conversion units are connected in series through output ends to form an energy storage converter string, and at least one energy storage converter string is connected between the positive pole and the negative pole of the direct-current power grid; the energy storage conversion unit comprises: an energy storage high-voltage isolation type DC/DC converter 102, or at least two energy storage high-voltage isolation type DC/DC converters 102 with parallel output ends;
the input ends of the energy storage high-voltage isolation type DC/DC converters 102 are connected in parallel with an energy storage device.
For the input ends of each energy storage high-voltage isolated DC/DC converter 102 in the energy storage converter string, the input ends of all the energy storage high-voltage isolated DC/DC converters 102 may be connected in parallel to the same energy storage device (see fig. 1 a); the input ends of all energy storage high-voltage isolated DC/DC converters 102 in one part of energy storage conversion units with serially connected output ends may be connected in parallel to the same energy storage device, the input ends of all energy storage high-voltage isolated DC/DC converters 102 in another part of energy storage conversion units with serially connected output ends may be connected in parallel to another energy storage device (see fig. 1b), of course, the same energy storage converter may be serially divided into a plurality of parts and respectively connected to different energy storage devices, and the number of energy storage conversion units connected to each energy storage device is not specifically limited herein; or alternatively, the input end of each energy storage high-voltage isolated DC/DC converter 102 in each energy storage conversion unit and the input end of the corresponding energy storage high-voltage isolated DC/DC converter 102 in other energy storage units are connected in parallel to the same energy storage device (see fig. 1 c); or one energy storage converter can be serially divided into a plurality of parts, and in each part, the input end of each energy storage high-voltage isolation type DC/DC converter 102 in each energy storage conversion unit is respectively connected with the input end of a corresponding single energy storage high-voltage isolation type DC/DC converter 102 in other energy storage units in parallel to the same energy storage device; it is not specifically limited herein, and is within the scope of the present application, depending on the particular environment in which it is used.
This alternating current-direct current hybrid photovoltaic power generation energy storage system that this embodiment provided, the energy storage converter that constitutes by a plurality of energy storage high voltage isolated DC/DC converters 102 is connected to direct current electric wire netting in series, and each energy storage high voltage isolated DC/DC converter 102 adopts the parallelly connected structure of output series connection input, through such framework for the route adjustment that charges energy storage device from the photovoltaic module side is: the photovoltaic module generates power and passes through a photovoltaic high-voltage isolation type DC/DC converter 101, and then passes through an energy storage high-voltage isolation type DC/DC converter 102 to charge an energy storage device, and the two stages are total; and the path of discharge from the energy storage device is: the energy storage device discharges electricity to the power grid through the energy storage high-voltage isolation type DC/DC converter 102 and then through the cascade module, and the total number of the energy storage device is two. Therefore, in the energy storage conversion process under the structure, part of charging and discharging paths only need to pass through four stages, so that the overall conversion efficiency is improved compared with the prior art.
It is worth mentioning that, with the development of technology, future power systems will include situations where a dc grid and an ac grid coexist, which means that future photovoltaic power generation systems may need to connect the ac grid and the dc grid at the same time; as is well known, a medium-high voltage dc power grid can transmit electric energy with less loss than a medium-high voltage ac power grid, and is more suitable for transmitting electric energy over a long distance. Therefore, in the field of new energy power generation, a medium-high voltage direct current power grid and/or a medium-high voltage alternating current-direct current hybrid power grid are increasingly adopted for electric energy transmission in the future; however, the prior art solutions are generally only capable of connecting one of the ac and low-voltage dc networks.
On the one hand, the ac/dc hybrid photovoltaic power generation energy storage system provided by this embodiment adopts the above connection manner by the modular multilevel cascade module, so that the whole photovoltaic power generation system can be connected to an ac power grid and a dc power grid at the same time; on the other hand, the high-voltage isolation type DC/DC converter 101 in the present embodiment includes: the isolation voltage grade between the primary side and the secondary side of the high-frequency transformer is more than or equal to 10kV, so that the alternating current-direct current hybrid photovoltaic power generation energy storage system can be used for merging electric energy in the connected photovoltaic modules into a medium-high voltage power grid; the voltage grade between the primary side and the secondary side can be set according to specific application environments so as to adapt to different photovoltaic system applications; it is not specifically limited herein and is within the scope of the present application.
In addition, in the above embodiment, the input ends of the respective photovoltaic high-voltage isolated DC/DC converters 101 in the photovoltaic converter string may be respectively used to connect the respective corresponding photovoltaic modules (as shown in fig. 1a to 1 d); alternatively, the input terminals of the respective photovoltaic high-voltage isolated DC/DC converters 101 in the photovoltaic converter string may be connected in parallel to connect the same photovoltaic module (not shown); or, in the photovoltaic converter string, the input ends of the photovoltaic high-voltage isolated DC/DC converters 101 connected in series at one part of the output ends are connected in parallel to connect the same photovoltaic module, and the input ends of the photovoltaic high-voltage isolated DC/DC converters 101 connected in series at the other part of the output ends are connected in parallel to connect another same photovoltaic module (not shown); it is not specifically limited herein, and is within the scope of the present application, depending on the particular environment in which it is used.
On this basis, preferably, the ac-dc hybrid photovoltaic power generation and energy storage system further includes: a plurality of optimizer groups;
the input end of the photovoltaic high-voltage isolation type DC/DC converter 101 is connected with the output end of at least one optimizer group;
the optimizer group comprises at least one optimizer, the output ends of the optimizers are connected in series, the two ends of the optimizer group are the output ends of the optimizer group, and the input end of the optimizer is connected with at least one photovoltaic module.
For the input end of each photovoltaic high-voltage isolated DC/DC converter 101 in the photovoltaic converter string, it may be connected to the output end of at least one optimizer group, respectively; or the input ends of each photovoltaic high-voltage isolated DC/DC converter 101 in the photovoltaic converter string are connected in parallel, and the two ends after being connected in parallel are connected with the output end of at least one optimizer group; or, the input ends of a plurality of photovoltaic high-voltage isolated DC/DC converters 101 in the photovoltaic converter string may be connected in parallel, and both ends after being connected in parallel are connected with the output end of at least one optimizer group; it is not specifically limited herein, and is within the scope of the present application, depending on the particular environment in which it is used.
Optionally, the optimizer is a non-isolated DC/DC converter.
Preferably, the optimizer is configured to implement MPPT (Maximum Power Point Tracking) control for the connected dc Power source.
Preferably, the alternating current-direct current hybrid photovoltaic power generation energy storage system may further include: and the confluence boxes are used for converging the output of the connected optimizer groups and outputting the converged direct current electric energy to the corresponding photovoltaic high-voltage isolated DC/DC converter 101.
In a specific actual design process, the MPPT control function belonging to a DC/DC converter in the prior art is handed over to a corresponding optimizer, so that the photovoltaic high-voltage isolation type DC/DC converter 101 does not need to carry out MPPT control and real-time voltage regulation on a connected photovoltaic module, the gain range of the photovoltaic high-voltage isolation type DC/DC converter is enabled to be smaller, namely the quotient of the maximum gain value of the ratio of the output voltage to the input voltage divided by the minimum gain value of the ratio of the output voltage to the input voltage is designed, the efficiency of the photovoltaic high-voltage isolation type DC/DC converter 101 is further improved compared with the prior art, the system efficiency is improved, and the maximum efficiency is higher than 98.5%; in addition, the pressure of the high-frequency transformer in the photovoltaic high-voltage isolated DC/DC converter 101 can be reduced.
Specifically, due to the use of the optimizer, the gain range of the photovoltaic high-voltage isolated DC/DC converter 101 can be greater than or equal to 1 and less than 1.5, for example, the gain range can be designed to be less than 1.5 times, and even the photovoltaic high-voltage isolated DC/DC converter 101 can be designed to have a fixed gain for open-loop control, so that the control function of the photovoltaic high-voltage isolated DC/DC converter 101 is simplified, and the design difficulty of the photovoltaic high-voltage isolated DC/DC converter 101 is reduced. Meanwhile, the problem of mismatch of series connection and parallel connection of components in the prior single MPPT control corresponding to one direct current bus is solved by the application of the optimizer, the MPPT control of a component level is realized, the power generation capacity of a system is improved, and each photovoltaic component can be monitored. And the whole system scheme improves the power density compared with the conventional system.
The rest of the principle is the same as the above embodiments, and is not described in detail here.
Another embodiment of the present invention further provides a specific ac/dc hybrid photovoltaic power generation and energy storage system, based on the above embodiment and fig. 1a to 1 d:
optionally, the main circuit of the cascaded module is a half-bridge topology (as shown in fig. 2 a) or a full-bridge topology (as shown in fig. 2 b).
Optionally, the main circuit of the photovoltaic high-voltage isolated DC/DC converter 101 is any one of an LC series resonance topology (as shown in fig. 3 a), an LLC series resonance topology (as shown in fig. 3 b), a dual-active DC/DC topology (as shown in fig. 3 c), a full-bridge DC/DC topology (as shown in fig. 3 d), a power bidirectional LC series resonance topology, and a power bidirectional LLC series resonance topology; fig. 3a to 3d are only examples of two-level topologies, and are not limited thereto, in practical applications, the LC series resonance topology, the LLC series resonance topology, and the dual-active DC/DC topology may also be three-level topologies, and of course, other topologies may be selected according to the specific application environment, and the topologies are not specifically limited herein, and all are within the protection scope of the present application.
Optionally, the main circuit of the energy storage high-voltage isolation type DC/DC converter 102 is any one of a dual-active DC/DC topology (as shown in fig. 3 c), a power bidirectional LC series resonance topology, and a power bidirectional LLC series resonance topology; of course, other topologies may be selected according to the specific application environment, and are not specifically limited herein and are within the scope of the present application.
Preferably, the main circuits of the photovoltaic high-voltage isolated DC/DC converter 101 and the energy-storage high-voltage isolated DC/DC converter 102 are both a multi-winding single-input multi-output structure, that is, one DC/AC module is connected to the primary winding, a plurality of AC/DC modules are respectively connected to each secondary winding, and each output port (i.e., the output end of the AC/DC module) is connected in series to obtain the output end of the corresponding main circuit, as shown in fig. 4.
In practical application, this alternating current-direct current hybrid photovoltaic power generation energy storage system should still include: the system comprises a system communication module, a system detection module, a system auxiliary power supply and at least one system controller;
the system controller is used for realizing grid-connected control on each cascade module;
the system detection module is used for detecting the voltage, the current, the temperature and the electric arc of the alternating current-direct current hybrid photovoltaic power generation energy storage system;
the system communication module is used for realizing communication between the system controller and other controllers and the outside;
the system auxiliary power supply is used for supplying power to the system communication module, the system detection module and the system controller.
Preferably, the cascade module comprises: the device comprises a main circuit, a communication module, a detection module, an auxiliary power supply and at least one controller;
the controller is used for controlling the action of a switching tube in a main circuit of the controller;
the detection module is used for realizing the voltage, current, temperature and arc detection of the cascade module;
the communication module is used for realizing the communication between the controller and the system controller;
the auxiliary power supply is used for supplying power for the communication module, the detection module and the controller.
Preferably, the photovoltaic high-voltage isolated DC/DC converter 101 includes: the device comprises a main circuit, a communication module, a detection module, an auxiliary power supply and at least one controller;
the controller is used for detecting and outputting the state of the photovoltaic high-voltage isolation type DC/DC converter 101;
the detection module is used for detecting the voltage, the current, the temperature and the electric arc of the photovoltaic high-voltage isolation type DC/DC converter 101;
the communication module is used for realizing the communication between the controller and the system controller or the cascade module;
the auxiliary power supply is used for supplying power for the communication module, the detection module and the controller.
Preferably, the energy storage high-voltage isolation type DC/DC converter 102 includes: the device comprises a main circuit, a communication module, a detection module, an auxiliary power supply and at least one controller;
the controller is used for detecting and outputting the state of the energy storage high-voltage isolation type DC/DC converter 102;
the detection module is used for detecting the voltage, the current, the temperature and the electric arc of the energy storage high-voltage isolation type DC/DC converter 102;
the communication module is used for realizing the communication between the controller and the system controller or the cascade module;
the auxiliary power supply is used for supplying power for the communication module, the detection module and the controller.
In a Specific practical Application, the system controller of the ac/DC hybrid photovoltaic power generation and energy storage system, the controller of the photovoltaic high-voltage isolated DC/DC converter 101, the controller of the energy storage high-voltage isolated DC/DC converter 102, and the controller of the cascade module may be multiple ones, and may be implemented by any one of a CPU (Central Processing Unit ), an MCU (micro controller Unit), a DSP (Digital Signal Processor), an ARM Processor, an FPGA (Field-Programmable Gate Array), a CPLD (Complex Programmable Logic Device), and an ASIC (Application Specific integrated circuit) chip, which are not specifically limited herein depending on the Specific Application environment, and are all within the protection scope of the present Application.
The specific implementation forms of the communication module, the detection module and the auxiliary power supply may all be determined according to the environment, and are not specifically limited herein and are within the scope of the present application.
Optionally, the energy storage device is: any one of a battery unit, a flywheel energy storage device, a pumped storage energy storage device and a heat energy storage device; or,
this energy storage device includes: the battery unit is connected with the converter, the battery unit is connected with one end of the converter, and the other end of the converter is used for connecting the energy storage high-voltage isolation type DC/DC converter 102, see FIG. 5.
Optionally, the inductance device 103 includes two identical inductances connected in series, and a connection point of the series connection is a midpoint of the inductance device 103;
alternatively, the inductive device 103 is an inductor with a center tap, and the center tap is the center of the inductive device 103.
In addition, in practical applications, the filter 104 may be: any one of an L filter, an LC filter, an LCL filter and a high-order filter; of course, other topologies may be selected according to the specific application environment, and are not specifically limited herein and are within the scope of the present application.
The rest of the principle is the same as the above embodiments, and is not described in detail here.
The embodiments of the invention are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments can be referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present teachings, or modify equivalent embodiments to equivalent variations, without departing from the scope of the present teachings, using the methods and techniques disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.
Claims (9)
1. The utility model provides a hybrid photovoltaic power generation energy storage system of alternating current-direct current which characterized in that includes: the system comprises a plurality of photovoltaic high-voltage isolated DC/DC converters, a plurality of energy storage high-voltage isolated DC/DC converters, at least one energy storage device, M upper bridge arms, M lower bridge arms, M inductance devices, a filter and a plurality of optimizer groups; wherein:
one end of each upper bridge arm is connected with one end of the corresponding lower bridge arm through one inductance device;
the middle point of each inductance device is connected with an alternating current power grid through the filter;
the other end of each upper bridge arm is connected, and the connecting point is connected with the anode of a direct current power grid;
the other end of each lower bridge arm is connected, and a connecting point is connected with the negative electrode of the direct current power grid;
the upper bridge arm and the lower bridge arm respectively comprise N cascade modules which are connected in series through an alternating current side, and N is a positive integer; the direct current side of the cascade module is suspended;
the photovoltaic conversion units are connected in series through output ends to form photovoltaic converter strings, and at least one photovoltaic converter string is connected between the positive pole and the negative pole of the direct current power grid; the photovoltaic conversion unit includes: the photovoltaic high-voltage isolated DC/DC converter or the photovoltaic high-voltage isolated DC/DC converters with at least two output ends connected in parallel;
the input end of the photovoltaic high-voltage isolation type DC/DC converter is connected with the output end of at least one optimizer group; wherein the optimizer is a non-isolated DC/DC converter;
the optimizer group comprises at least one optimizer, the output ends of the optimizers are connected in series, the output end of the optimizer group is connected at the two ends of the series connection, and the input end of the optimizer is connected with at least one photovoltaic module;
the optimizer is used for realizing Maximum Power Point Tracking (MPPT) control on the connected photovoltaic modules;
the input end of the photovoltaic high-voltage isolation type DC/DC converter is used for connecting a photovoltaic assembly;
the photovoltaic high-voltage isolation type DC/DC converter comprises: the isolation voltage grade between the primary side and the secondary side of the high-frequency transformer is more than or equal to 10kV, so that the alternating current-direct current hybrid photovoltaic power generation energy storage system can be used for merging electric energy in the connected photovoltaic modules into a medium-high voltage power grid;
the energy storage conversion units are connected in series through output ends to form an energy storage converter string, and at least one energy storage converter string is connected between the positive pole and the negative pole of the direct current power grid; the energy storage conversion unit comprises: the energy storage high-voltage isolation type DC/DC converter or the energy storage high-voltage isolation type DC/DC converters with at least two output ends connected in parallel;
the input ends of the energy storage high-voltage isolation type DC/DC converters are connected in parallel with one energy storage device.
2. The alternating current-direct current hybrid photovoltaic power generation and energy storage system according to claim 1, wherein the input end of each photovoltaic high-voltage isolated DC/DC converter in the photovoltaic converter string is respectively used for connecting a corresponding photovoltaic module; or,
the input ends of the photovoltaic high-voltage isolated DC/DC converters in the photovoltaic converter string are connected in parallel to be connected with the same photovoltaic module; in the alternative to this, either,
in the photovoltaic converter string, a plurality of input ends of the photovoltaic high-voltage isolation type DC/DC converters with the output ends connected in series are connected in parallel to be connected with the same photovoltaic module.
3. The ac-dc hybrid photovoltaic power generation and energy storage system of claim 1, further comprising: and the combiner box is used for combining the outputs of the connected optimizer groups and outputting the combined direct current electric energy to the corresponding photovoltaic high-voltage isolated DC/DC converter.
4. The alternating current-direct current hybrid photovoltaic power generation and energy storage system according to claim 1, wherein the input ends of the energy storage high-voltage isolation type DC/DC converters in the energy storage converter string are connected in parallel, and the two ends of the energy storage high-voltage isolation type DC/DC converters after being connected in parallel are connected with the energy storage device; or,
in the energy storage converter string, the input ends of all the energy storage high-voltage isolation type DC/DC converters in the energy storage conversion units with a plurality of output ends connected in series are connected in parallel, and the two ends after being connected in parallel are connected with the corresponding energy storage devices; in the alternative to this, either,
in the energy storage converter string, the input ends of the energy storage high-voltage isolated DC/DC converters corresponding to the energy storage conversion units are connected in parallel, and the two ends after being connected in parallel are connected with the corresponding energy storage devices; still alternatively, the first and second substrates may be,
in the energy storage converter string, the input ends of the single energy storage high-voltage isolated DC/DC converter corresponding to the energy storage conversion units with the output ends connected in series are connected in parallel, and the two ends after being connected in parallel are connected with the corresponding energy storage devices.
5. The AC-DC hybrid photovoltaic power generation and energy storage system according to any one of claims 1-4, wherein the main circuit of the cascade module is a half-bridge topology or a full-bridge topology.
6. The AC-DC hybrid photovoltaic power generation and energy storage system according to any one of claims 1-4, wherein a main circuit of the photovoltaic high-voltage isolation type DC/DC converter is any one of an LC series resonance topology, an LLC series resonance topology, a dual-active DC/DC topology, a full-bridge DC/DC topology, a power bidirectional LC series resonance topology and a power bidirectional LLC series resonance topology.
7. The AC-DC hybrid photovoltaic power generation and energy storage system according to any one of claims 1-4, wherein a main circuit of the energy storage high-voltage isolation type DC/DC converter is any one of a double-active DC/DC topology, a power bidirectional LC series resonance topology and a power bidirectional LLC series resonance topology.
8. The alternating current-direct current hybrid photovoltaic power generation and energy storage system according to any one of claims 1 to 4, wherein main circuits of the photovoltaic high-voltage isolation type DC/DC converter and the energy storage high-voltage isolation type DC/DC converter are both of a multi-winding single-input multi-output structure, and output ports are connected in series to obtain output ends of the corresponding main circuits.
9. The AC-DC hybrid photovoltaic power generation and energy storage system according to any one of claims 1-4, wherein the energy storage device is: any one of a battery unit, a flywheel energy storage device, a pumped storage energy storage device and a heat energy storage device; or,
the energy storage device includes: the battery unit is connected with the converter, the battery unit is connected with one end of the converter, and the other end of the converter is used for being connected with the energy storage high-voltage isolation type DC/DC converter.
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