CN219086813U - Grid-connected power generation system - Google Patents
Grid-connected power generation system Download PDFInfo
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- CN219086813U CN219086813U CN202223022634.6U CN202223022634U CN219086813U CN 219086813 U CN219086813 U CN 219086813U CN 202223022634 U CN202223022634 U CN 202223022634U CN 219086813 U CN219086813 U CN 219086813U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The application discloses a grid-connected power generation system, include: breaking equipment and a transformer; the transformer is connected with a power grid through breaking equipment; when the power supply is in standby, the breaking equipment disconnects the transformer from the power grid; when the power supply works, the breaking equipment is closed to connect the transformer with the power grid; the breaking equipment is also used for disconnecting the transformer from the power grid when the power grid or the grid-connected power generation system is abnormal, and protecting the transformer. When the power supply connected with the primary side of the transformer meets breaking conditions, the breaking equipment disconnects the power grid of the transformer so as to avoid no-load loss caused by continuous connection of the transformer with the power grid. In addition, the breaking equipment has a relay protection function, and when the system is abnormal, the connection between the transformer and the power grid is timely disconnected, so that a protection effect is achieved. Because relay protection and breaking function are integrated into one set of equipment, two different functions can be realized by using one set of switch, so that hardware is saved, and cost can be reduced.
Description
Technical Field
The application relates to the technical field of new energy power generation, in particular to a grid-connected power generation system.
Background
At present, a grid-connected power generation system comprises a plurality of subarrays, each subarray comprises a plurality of inverters, the output ends of the inverters of each subarray are converged and then transformed by corresponding subarray transformers, and energy is fed to a power grid after transformation.
For example, when the direct current source of the grid-connected power generation system is a photovoltaic array, the inverter is in a standby state due to poor illumination conditions such as night or overcast and rainy days, if the transformer is always connected with the power grid, no-load loss can be generated, and in the prior art, the disconnection switch is independently added, so that the cost is high.
Disclosure of Invention
In view of this, the present application provides a grid-connected power generation system, which can disconnect the transformer from the power grid when the inverter is in a standby state, reduce no-load loss, and integrate with the relay protection system, thereby reducing hardware complexity.
The application provides a grid-connected power generation system, comprising: breaking equipment and a transformer;
the transformer is connected with a power grid through breaking equipment;
when the power supply is in standby, the breaking equipment disconnects the transformer from the power grid; when the power supply works, the breaking equipment is closed to connect the transformer with the power grid;
the breaking equipment is also used for disconnecting the transformer from the power grid when the power grid or the grid-connected power generation system is abnormal, and protecting the transformer.
Preferably, the power supply includes: n subarrays;
each sub-array comprises at least one energy conversion device;
n transformers are provided; n is an integer greater than or equal to 1;
the N subarrays are in one-to-one correspondence with the N transformers, the output end of each subarray is connected with the primary side of the corresponding transformer, and the secondary sides of all the transformers are connected with a power grid through breaking equipment.
Preferably, the power supply includes: n subarrays; n is an integer greater than or equal to 1;
each sub-array comprises a plurality of energy conversion devices;
a plurality of subarrays correspond to one transformer;
the output end of each subarray is connected with the primary side of the corresponding transformer, and the secondary sides of all transformers are connected with a power grid through breaking equipment.
Preferably, the method further comprises: a voltage detection circuit, a communication circuit and a controller;
a voltage detection circuit for detecting voltages at both ends of the breaking device;
the controller is communicated with the breaking equipment through a communication circuit;
and the controller is used for controlling the breaking equipment to be closed when the voltages at the two ends of the breaking equipment are the same in amplitude and phase.
Preferably, the controller is in communication connection with the energy conversion devices in each subarray, and controls the breaking device to be disconnected when all the energy conversion devices meet breaking conditions.
Preferably, the controller is further configured to control at least one of a voltage, a current and a power of the energy conversion device.
Preferably, when the power grid is three-phase, the breaking equipment comprises three groups of independent switches, and each phase of the three-phase power grid is connected with one group of switches in series;
when the breaking equipment is closed, the three groups of independent switches are closed independently and sequentially.
Preferably, the switch in the breaking device is a high voltage switch.
Preferably, the transformer is a step-up transformer.
Preferably, the input of the energy conversion device is used for connecting an ac or dc source.
Preferably, the energy conversion device is an inverter, the input of which is used for connecting a battery or a photovoltaic array.
From this, this application has following beneficial effect:
the grid-connected power generation system comprises a transformer and breaking equipment, wherein the breaking equipment is connected between the transformer and a power grid, and when a power supply connected with the primary side of the transformer meets breaking conditions, the breaking equipment disconnects the power grid of the transformer so as to avoid no-load loss generated when the transformer is continuously connected with the power grid. In addition, the breaking equipment has a relay protection function, and when the system is abnormal, the connection between the transformer and the power grid is timely disconnected, so that a protection effect is achieved. Because relay protection and breaking function are integrated into one set of equipment, two different functions can be realized by using one set of switch, so that hardware is saved, and cost can be reduced.
Drawings
Fig. 1 is a schematic diagram of a grid-connected power generation system provided in an embodiment of the present application;
fig. 2 is a schematic diagram of another grid-connected power generation system according to an embodiment of the present application;
fig. 3 is a schematic diagram of still another grid-connected power generation system according to an embodiment of the present application.
Detailed Description
Conventionally, in order to ensure that a relay protection system is arranged between a transformer and a power grid when a grid-connected power generation system is abnormal, the relay protection system acts to protect each device when the transformer and the power grid are abnormal, namely, the connection between the transformer and the power grid is disconnected.
In order to reduce the loss of the transformer when the power supply is in idle load, the breaking equipment can be set to disconnect the connection between the transformer and the voltage, if the breaking equipment and a switch in the relay protection system are set, the hardware is redundant, two sets of breaking devices are required to be set, namely, a relay protection cabinet is required to be set for the grid-connected power generation system, and a breaking equipment cabinet is also required to be set, so that the hardware of the grid-connected power generation system is complex, and the system transformation and maintenance cost are increased.
Therefore, in order to solve the technical problem, the switch and the breaking equipment in the relay protection system are combined into one, namely, the breaking equipment provided by the embodiment of the application can realize the relay protection function and disconnect the connection between the transformer and the power grid when the power supply is in standby. For example, the grid-connected power generation system is a photovoltaic system, and the photovoltaic array hardly generates power or outputs little electric energy under the condition of poor illumination conditions such as night or rainy days, so that the inverters in the subarrays are in a standby state, and the transformers are always connected with a medium-high voltage power grid, so that no-load loss is generated by the transformers when the inverters are in standby state, and the loss is relatively large due to the fact that the capacity of the transformers is relatively large and the transformers are in no-load operation for a long time. Therefore, when the power supply is on standby, the breaking device is required to operate, and the connection between the transformer and the power grid is disconnected.
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures and detailed description are described in further detail below.
Referring to fig. 1, the diagram is a schematic diagram of a grid-connected power generation system provided in an embodiment of the present application.
The grid-connected power generation system provided in this embodiment includes: a breaking apparatus 100 and a transformer; the number of transformers is not particularly limited, and may be one or more, and when the grid-connected power generation system is a photovoltaic system, a plurality of transformers may be present. The transformer is connected with the power grid through breaking equipment. For example, N transformers, the primary sides of which are connected to corresponding power sources, and the secondary sides of which are all connected to a power grid, for example, a medium-high voltage BUS, through breaking equipment 100. The power supply can be a direct current source or an alternating current source, and when the power supply is a direct current source, the power supply also comprises subarrays, and each subarray comprises at least one energy conversion device, so that the direct current source is converted into the alternating current source and the alternating current source is provided as the primary side of the transformer.
The embodiment of the application does not specifically limit the specific voltage level of the power grid, for example, the voltage level may be tens of kV or tens of kV, and one example is 35kV, and may also be other voltage levels, which are not specifically limited herein.
The secondary side of the first transformer T1 is connected with the BUS through the breaking equipment 100, and the secondary side of the second transformer T2 is connected with the BUS through the breaking equipment 100 until the secondary side of the Nth transformer TN is connected with the BUS through the breaking equipment 100.
The embodiment of the present application does not particularly limit the specific type of the breaking apparatus 100, and may be, for example, a high-voltage switch. In fig. 1, only one switch is illustrated as an example, it should be understood that when the power grid is a three-phase power grid, the breaking apparatus 100 may include three sets of high voltage switches, each corresponding one of the sets of high voltage switches. Each group of high-voltage switches comprises at least one high-voltage switch and can also comprise a plurality of high-voltage switches connected in series.
The specific type of energy conversion device is also not specifically defined herein, and may include an inverter depending on the type of power source to which the energy conversion device is input connected, e.g., the power source is a direct current source. The power source is an ac source, and the energy conversion device may be an ac-dc-ac conversion device or an ac-ac conversion device.
The primary side of the transformer is used for connecting a power supply; the following description will take a power supply as a direct current source as an example, and the energy conversion device is an inverter. For example, the primary side of the transformer is connected with a subarray in the grid-connected power generation system, each subarray can comprise at least one inverter, and the input end of each inverter is connected with a corresponding photovoltaic array.
The present embodiment does not specifically limit the specific number of subarrays and the transformer, for example, the number of subarrays may be equal to the number of transformers, that is, in a one-to-one correspondence.
In addition, a plurality of subarrays may correspond to one transformer. The power supply includes: n subarrays; n is an integer greater than or equal to 1; each sub-array comprises at least one energy conversion device; the output end of each subarray is connected with the primary side of the corresponding transformer.
When the power supply is in standby, namely the power supply does not output electric energy, the primary side of the transformer does not have electric energy input, and the breaking equipment disconnects the secondary side of the transformer from the power grid; when the power supply works, the breaking equipment is closed to enable the secondary side of the transformer to be connected with the power grid, and then the electric energy output by the subarrays is fed back to the power grid;
the breaking equipment is also used for disconnecting the secondary side of the transformer from the power grid when the power grid or the grid-connected power generation system is abnormal, namely, the breaking equipment has the relay protection function at the same time, and when the protection is needed, the connection between the transformer and the power grid is disconnected in time, so that high-voltage devices such as the transformer are protected.
The grid-connected power generation system comprises a transformer and breaking equipment, wherein the breaking equipment is connected between the transformer and a power grid, and when a power source connected with the primary side of the transformer is in standby, the breaking equipment disconnects the power grid of the transformer so as to avoid the transformer from being continuously connected with the power grid and generating no-load loss. In addition, the breaking equipment has a relay protection function, and when the system is abnormal, the connection between the transformer and the power grid is timely disconnected, so that a protection effect is achieved. Because relay protection and breaking function are integrated into one set of equipment, two different functions can be realized by using one set of switch, so that hardware is saved, and cost can be reduced.
In the following, the power supply includes a plurality of subarrays, one subarray corresponds to each transformer, that is, the number of the subarrays is equal, and the energy conversion device is taken as an inverter for example.
Referring to fig. 2, a schematic diagram of another grid-connected power generation system according to an embodiment of the present application is shown.
The grid-connected power generation system provided in this embodiment, wherein the power supply includes: n subarrays; i.e. the first sub-array 201, the second sub-array 202, and up to the nth sub-array 20N. N transformers are provided; n is an integer greater than or equal to 1; the N subarrays are in one-to-one correspondence with the N transformers, the output end of each subarray is connected with the primary side of the corresponding transformer, and the secondary sides of all the transformers are connected with a power grid through breaking equipment.
Each sub-array includes a plurality of inverters; the input of each inverter is connected to a corresponding photovoltaic array, it being understood that some inverters may be connected to the photovoltaic array and some to the battery.
The first subarray 201 is connected with the primary side of the first transformer T1, the second subarray 202 is connected with the primary side of the second transformer T2, and the Nth subarray 20N is connected with the primary side of the Nth transformer TN.
The grid-connected power generation system provided in this embodiment further includes: a voltage detection circuit and a controller.
Referring to fig. 3, a schematic diagram of still another grid-connected power generation system according to an embodiment of the present application is shown.
The first subarray 201 is connected to the primary side of the first transformer T1, and the second subarray 202 is connected to the primary side of the second transformer T2.
The grid-connected power generation system provided by the embodiment further comprises a voltage detection circuit and a communication circuit (not shown in the figure), wherein the voltage detection circuit is used for detecting voltages at two ends of the breaking equipment; the controller communicates with the breaking apparatus through the communication circuit. It should be appreciated that the voltage detection circuit may be two, i.e. one on the transformer side and one on the grid side; in addition, the voltage detection circuit may be one, so as to detect the voltages at two ends of the breaking device 100, and the controller controls the breaking device 100 to be closed only when the voltages at two ends are synchronous, thereby avoiding generating larger impact current for the breaking device.
That is, the controller 200 is used to control the breaking apparatus 100 to be closed when the output voltage of the secondary side is the same in magnitude and phase as the voltage of the power grid.
And a controller for controlling at least one of voltage, current and power of the energy conversion device.
In addition, the controller 200 provided in the embodiment of the present application is in communication connection with a plurality of inverters in each subarray, and when all the inverters meet the disconnection conditions, the breaking device 100 is controlled to be disconnected, so that the connection between all the transformers and the power grid is disconnected, and no-load loss of the transformers is avoided. The off condition may be that the inverter is in a standby state due to low dc source voltage at the input end, or may be other operating conditions that the inverter needs maintenance and the like and needs to be turned off.
In addition, when the power supply grid is three-phase, the breaking equipment comprises three independent switches, and each phase of the three-phase grid is connected with one switch in series;
if the power supply is not standby, for example, in daytime, the photovoltaic array outputs electric energy, and when grid-connected power generation is needed, the breaking equipment needs to be closed, and three independent switches are sequentially closed. For example, breaking equipment of the corresponding phase is controlled to be disconnected at the peak point of the voltage of each phase of the power grid, so that exciting current impact on the transformer is small, and the transformer can be effectively protected.
The grid-connected power generation system provided by the embodiment of the application further comprises: a power supply device;
and the power supply device is used for taking power from a power grid or taking power from the secondary side of the transformer to supply power for the controller.
In one possible implementation manner, the transformer in the grid-connected power generation system provided in the embodiment of the present application may be a step-up transformer, that is, grid-connected after boosting the output voltage of the corresponding subarray.
According to the grid-connected power generation system, the breaking function and the relay protection function between the transformer and the power grid are integrated, so that the transformation cost of the grid-connected power generation system can be greatly reduced.
It should be noted that, in the present description, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different manner from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the system or device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant points refer to the description of the method section.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (11)
1. A grid-tie power generation system, comprising: breaking equipment and a transformer;
the transformer is connected with a power grid through the breaking equipment;
when the power supply is in standby, the breaking equipment disconnects the transformer from the power grid; when the power supply works, the breaking equipment is closed to connect the transformer with the power grid;
the breaking equipment is also used for disconnecting the transformer from the power grid when the power grid or the grid-connected power generation system is abnormal, and protecting the transformer.
2. The system of claim 1, wherein the power source comprises: n subarrays;
each of said sub-arrays comprising at least one energy conversion device;
the number of the transformers is N; the N is an integer greater than or equal to 1;
the N subarrays are in one-to-one correspondence with the N transformers, the output end of each subarray is connected with the primary side of the corresponding transformer, and the secondary sides of all transformers are connected with the power grid through the breaking equipment.
3. The system of claim 1, wherein the power source comprises: n subarrays; the N is an integer greater than or equal to 1;
each of the subarrays comprises a plurality of energy conversion devices;
a plurality of subarrays correspond to one transformer;
the output end of each subarray is connected with the primary side of the corresponding transformer, and the secondary sides of all transformers are connected with the power grid through the breaking equipment.
4. A system according to claim 2 or 3, further comprising: a voltage detection circuit, a communication circuit and a controller;
the voltage detection circuit is used for detecting voltages at two ends of the breaking equipment;
the controller is communicated with the breaking equipment through the communication circuit;
the controller is used for controlling the breaking equipment to be closed when the voltages at the two ends of the breaking equipment are the same in amplitude and phase.
5. The system of claim 4, wherein the controller is communicatively coupled to the energy conversion devices in each of the sub-arrays and controls the breaking apparatus to break when all of the energy conversion devices meet a breaking condition.
6. The system of claim 5, wherein the controller is further configured to control at least one of voltage, current, and power of the energy conversion device.
7. A system according to any one of claims 1-3, wherein when the grid is three-phase, the breaking device comprises three separate sets of switches, one set of said switches being connected in series to each phase of the three-phase grid;
when the breaking equipment is closed, the three groups of independent switches are closed independently and sequentially.
8. A system according to any one of claims 1-3, characterized in that the switch in the breaking device is a high voltage switch.
9. A system according to any one of claims 1-3, wherein the transformer is a step-up transformer.
10. A system according to claim 3, wherein the input of the energy conversion device is adapted to be connected to an ac or dc source.
11. The system of claim 10, wherein the energy conversion device is an inverter having an input for connection to a battery or a photovoltaic array.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223022634.6U CN219086813U (en) | 2022-11-14 | 2022-11-14 | Grid-connected power generation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223022634.6U CN219086813U (en) | 2022-11-14 | 2022-11-14 | Grid-connected power generation system |
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| Publication Number | Publication Date |
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| CN219086813U true CN219086813U (en) | 2023-05-26 |
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| CN202223022634.6U Active CN219086813U (en) | 2022-11-14 | 2022-11-14 | Grid-connected power generation system |
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| CN (1) | CN219086813U (en) |
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- 2022-11-14 CN CN202223022634.6U patent/CN219086813U/en active Active
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