CN117674255A - Control method, controller and photovoltaic system - Google Patents

Control method, controller and photovoltaic system Download PDF

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Publication number
CN117674255A
CN117674255A CN202311570692.9A CN202311570692A CN117674255A CN 117674255 A CN117674255 A CN 117674255A CN 202311570692 A CN202311570692 A CN 202311570692A CN 117674255 A CN117674255 A CN 117674255A
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China
Prior art keywords
voltage
power grid
state
photovoltaic system
power
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CN202311570692.9A
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Chinese (zh)
Inventor
王雅琳
卢雄伟
胡斌
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Xiamen Kehua Digital Energy Tech Co Ltd
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Xiamen Kehua Digital Energy Tech Co Ltd
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Priority to CN202311570692.9A priority Critical patent/CN117674255A/en
Publication of CN117674255A publication Critical patent/CN117674255A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The application provides a control method, a controller and a photovoltaic system. The method is applied to a photovoltaic system connected with a power grid, and comprises the following steps: judging whether the power grid is in a high-voltage state or a low-voltage state; when the power grid is in a high-voltage state, regulating a derating coefficient according to a first voltage so as to control the active power output by the photovoltaic system not to exceed a first limit power, wherein the first voltage is the bus voltage of the photovoltaic system, the derating coefficient is used for regulating a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient; when the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the first voltage to the second voltage so as to control the active power output by the photovoltaic system not to exceed the second limiting power, wherein the second voltage is the power grid voltage. The photovoltaic system and the power grid working reliability can be improved.

Description

Control method, controller and photovoltaic system
Technical Field
The application relates to the technical field of photovoltaic control, in particular to a control method, a controller and a photovoltaic system.
Background
The photovoltaic system is connected to the power grid, and in some cases, for example, the nonlinear load of the line is too high or the impedance of the line is too high, the power grid may be in a weak power grid state, and the disturbance resistance of the power grid is poor. In the weak power grid state, when the power grid voltage is abnormal, if the power grid requests the photovoltaic system to output active power for supporting, the output power can be fluctuated due to the voltage fluctuation of the photovoltaic system, and the power grid disturbance can be further aggravated, so that the working reliability of the photovoltaic system and the power grid is affected.
The control method is used for guaranteeing the working reliability of the photovoltaic system and the power grid in the weak power grid state.
Disclosure of Invention
The embodiment of the application provides a control method, a controller and a photovoltaic system, so as to ensure the working reliability of the photovoltaic system and a power grid in a weak power grid state.
In a first aspect, an embodiment of the present application provides a control method applied to a photovoltaic system connected to a power grid, including:
judging whether the power grid is in a high-voltage state or a low-voltage state, wherein the high-voltage state is a working state that the power grid voltage is larger than the rated maximum voltage of the power grid, and the low-voltage state is a working state that the power grid voltage is smaller than the rated minimum voltage of the power grid;
when the power grid is in a high-voltage state, regulating a derating coefficient according to a first voltage so as to control the active power output by the photovoltaic system not to exceed a first limit power, wherein the first voltage is the bus voltage of the photovoltaic system, the derating coefficient is used for regulating a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient;
when the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the first voltage to the second voltage so as to control the active power output by the photovoltaic system not to exceed the second limiting power, wherein the second voltage is the power grid voltage.
In one possible implementation, adjusting the derating factor according to the first voltage includes:
when the first voltage exceeds the preset voltage, the derating coefficient is controlled to be reduced until the first voltage does not exceed the preset voltage.
In one possible implementation, after controlling the derating factor to decrease, the control method further includes:
and if the power grid is recovered to a normal state from a high-voltage state, controlling the derating coefficient to be recovered to a default value.
In one possible implementation, adjusting the derating factor based on the ratio of the first voltage and the second voltage includes:
and when the ratio exceeds a preset ratio, controlling the derating coefficient to be reduced until the ratio does not exceed the preset ratio.
In one possible implementation, after controlling the derating factor to decrease, the control method further includes:
and if the power grid is recovered to a normal state from a low-voltage state, controlling the derating coefficient to be recovered to a default value.
In one possible implementation, determining that the power grid is in a high-voltage state or a low-voltage state includes:
and when an active power request of the power grid is received, acquiring the power grid voltage, and judging whether the power grid is in a high-voltage state or a low-voltage state according to the power grid voltage.
In a second aspect, the present application provides a control device for use in a photovoltaic system connected to a power grid, comprising:
the judging module is used for judging whether the power grid is in a high-voltage state or a low-voltage state, wherein the high-voltage state is a working state that the power grid voltage is larger than the rated maximum voltage of the power grid, and the low-voltage state is a working state that the power grid voltage is smaller than the rated minimum voltage of the power grid;
the first control module is used for adjusting a derating coefficient according to a first voltage when the power grid is in a high-voltage state so as to control the active power output by the photovoltaic system not to exceed the limit power, wherein the first voltage is the bus voltage of the photovoltaic system, the derating coefficient is used for adjusting a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient;
and the second control module is used for adjusting the derating coefficient according to the ratio of the first voltage to the second voltage when the power grid is in a low-voltage state so as to control the active power output by the photovoltaic system not to exceed the limit power, wherein the second voltage is the power grid voltage.
In a third aspect, embodiments of the present application provide a controller, including a memory and a processor, where the memory stores a computer program executable on the processor, and where the processor implements the steps of the control method as described above in the first aspect or any one of the possible implementations of the first aspect when the computer program is executed.
In a fourth aspect, embodiments of the present application provide a photovoltaic system comprising a controller according to the above third aspect.
In a fifth aspect, embodiments of the present application provide a computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of the control method as described above in the first aspect or any one of the possible implementations of the first aspect.
The embodiment of the application provides a control method, a controller and a photovoltaic system, wherein when a power grid is in a high-voltage state, the derating coefficient is adjusted according to the bus voltage of the photovoltaic system so as to reduce the output power of the photovoltaic system, ensure that the bus voltage of the photovoltaic system is not lifted, and avoid that the stability of the power grid is influenced by the output of higher active power. When the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the bus voltage to the power grid voltage, the bus voltage is reduced, the influence of high active power output on the stability of the power grid is avoided, and the working reliability of the power grid and the photovoltaic system is ensured.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required for the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a photovoltaic system provided in an embodiment of the present application;
FIG. 2 is a flowchart of an implementation of a control method provided in an embodiment of the present application;
fig. 3 is a schematic structural diagram of a control device according to an embodiment of the present application;
fig. 4 is a schematic diagram of a controller provided in an embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the following description will be made with reference to the accompanying drawings by way of specific embodiments.
Fig. 1 is a schematic structural diagram of a photovoltaic system provided in an embodiment of the present application, and as shown in fig. 1, the photovoltaic system may include a photovoltaic module, a DC/DC module, and a DC/AC module that are sequentially connected. Wherein the other end of the DC/AC module is connected with a power grid.
In the embodiment of the application, the direct current bus between the DC/DC module and the DC/AC module is a bus of a photovoltaic system, and the connection point between the DC/AC module and the power grid is a grid connection point of the photovoltaic system and the power grid.
The photovoltaic system is connected into a power grid, and the disturbance resistance of the power grid is poor under the condition of weak power grid. When the power grid is in an abnormal state, the voltage of a grid connection point of the photovoltaic system and the power grid fluctuates, so that the fluctuation of the output active power of the photovoltaic system can be influenced, the fluctuation of the power grid can be further aggravated, and the working reliability of the power grid and the working reliability of the photovoltaic system are influenced.
The embodiment of the application solves the problem that a power grid and a photovoltaic system are mutually influenced under the condition of a weak power grid by providing the control method of the optical system.
Referring to fig. 2, a flowchart of implementation of the control method provided in the embodiment of the present application is shown. As shown in fig. 2, a control method applied to a photovoltaic system connected to a power grid may include S101 to S103.
S101, judging whether the power grid is in a high-voltage state or a low-voltage state, wherein the high-voltage state is a working state that the power grid voltage is larger than the rated maximum voltage of the power grid, and the low-voltage state is a working state that the power grid voltage is smaller than the rated minimum voltage of the power grid.
The execution subject of the embodiments of the present application may be a general controller of a photovoltaic system or a controller of an inverter in a photovoltaic system.
The embodiment of the application can monitor the voltage of the power grid. When the grid voltage is greater than the rated maximum voltage of the grid, the grid can be judged to be in a high-voltage state. And when the power grid voltage is smaller than the rated minimum voltage of the power grid, the power grid can be judged to be in a low-voltage state. And when the power grid voltage is smaller than or equal to the rated maximum voltage of the power grid and is larger than or equal to the rated minimum voltage of the power grid, the power grid can be judged to be in a normal state. The high-voltage state and the low-voltage state are abnormal states of the power grid.
Optionally, the power grid can be judged to be in a high-voltage state or a low-voltage state in real time. Or when the active power request of the power grid is received, judging that the power grid is in a high-voltage state or a low-voltage state. The active request is used for indicating that the power grid requests the photovoltaic system to output active power.
S102, when the power grid is in a high-voltage state, regulating a derating coefficient according to a first voltage so as to control active power output by the photovoltaic system not to exceed first limiting power, wherein the first voltage is bus voltage of the photovoltaic system, the derating coefficient is used for regulating a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient.
And when the power grid voltage is greater than the rated maximum voltage of the power grid, indicating that the power grid is in a high-voltage state. When the power grid is in a high-voltage state, the voltage of the grid-connected point of the photovoltaic system and the power grid can be raised, so that the bus voltage of the photovoltaic system is raised, and the stability of the photovoltaic system is affected. And the bus voltage is increased to increase the output active power, so that the anti-interference performance of the power grid is poor under the condition of weak power grid, and the stability of the power grid is further affected. Eventually leading to a reduced operational reliability of both the grid and the photovoltaic system.
When the power grid is in a high-voltage state, the derating coefficient can be adjusted according to the first voltage so as to reduce the active power output by the photovoltaic system and avoid overhigh bus voltage of the photovoltaic system.
The bus voltage of the photovoltaic system is regulated by a bus voltage loop, and the bus voltage loop regulates the bus voltage according to the voltage feedback value and the given bus voltage so as to avoid the bus voltage from being too high or too low. When the voltage feedback value is increased, the bus voltage is increased, and when the voltage feedback value is decreased, the bus voltage is decreased. By adjusting the derate coefficient reduction, the bus voltage reduction can be adjusted.
In practical application, the bus voltage is in direct proportion to the active power, when the bus voltage is increased, the active power output by the photovoltaic system is increased, and when the bus voltage is reduced, the active power output by the photovoltaic system is reduced. Therefore, the bus voltage can be adjusted by adjusting the derating coefficient, and the active power output by the photovoltaic system can be further adjusted. That is, the active power output by the photovoltaic system decreases as the derating coefficient decreases.
In the embodiment of the application, the first voltage is a busbar voltage of the photovoltaic system, when the first voltage is too high, the output active power of the photovoltaic system may be too high, and at this time, the derating coefficient may be adjusted to limit the first voltage, so as to ensure that the active power output by the photovoltaic system does not exceed the first limiting power. The first limiting power is the maximum allowable output active power of the photovoltaic system in a high-voltage state of the power grid. Or the first limiting power is a power value of which the photovoltaic system is smaller than the maximum allowable output active power in the high-voltage state of the power grid.
And S103, when the power grid is in a low-voltage state, adjusting the derating coefficient according to the ratio of the first voltage to the second voltage so as to control the active power output by the photovoltaic system not to exceed the second limiting power, wherein the second voltage is the power grid voltage.
In embodiments of the present application, the ratio of the first voltage and the second voltage may be referred to as a differential pressure coefficient. And when the voltage of the power grid is smaller than the rated minimum voltage of the power grid, indicating that the power grid is at low voltage. When the bus voltage and the grid voltage are normal, the differential pressure coefficient is in a normal range. When the power grid is in a low-voltage state, the bus voltage can be reduced under normal conditions, so that the differential pressure coefficient is ensured to be in a normal range. However, if the differential pressure coefficient is increased, the bus voltage is increased or kept unchanged, which may cause the increase of the active power output by the photovoltaic system, further perturb the power grid, and the power grid fluctuation in turn also affects the stability of the photovoltaic system, and finally, the working reliability of the power grid and the photovoltaic system is reduced.
When the power grid is in a low-voltage state and the differential pressure coefficient is too high, the derating coefficient can be adjusted to be reduced so as to reduce the bus voltage of the photovoltaic system, and further ensure that the active power output by the photovoltaic system does not exceed the second limiting power. The second limiting power is the maximum allowable output active power of the photovoltaic system in the low-voltage state of the power grid. Or the second limiting power is a power value of which the photovoltaic system is smaller than the maximum allowable output active power in the low-voltage state of the power grid.
According to the embodiment of the application, when the power grid is in a high-voltage state, the derating coefficient is adjusted according to the bus voltage of the photovoltaic system, so that the output power of the photovoltaic system is reduced, the bus voltage of the photovoltaic system is not raised, and the influence of the output higher active power on the stability of the power grid is avoided. When the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the bus voltage to the power grid voltage, the bus voltage is reduced, the influence of high active power output on the stability of the power grid is avoided, and the working reliability of the power grid and the photovoltaic system is ensured.
In some embodiments of the present application, "adjusting the derating coefficient according to the first voltage" in S102 may include:
when the first voltage exceeds the preset voltage, the derating coefficient is controlled to be reduced until the first voltage does not exceed the preset voltage.
When the first voltage does not exceed the preset voltage, the derating coefficient is maintained unchanged.
When the grid voltage is greater than the rated maximum voltage of the grid, the grid voltage is in a high voltage state. At this time, if the bus voltage exceeds the preset voltage, the bus voltage is indicated to be too high, and at this time, the derating coefficient can be controlled to be gradually reduced so as to regulate the bus voltage until the bus voltage does not exceed the preset voltage, so as to control the active power output by the photovoltaic system not to exceed the first limiting power.
Alternatively, the derating factor may be gradually linearly reduced until the bus voltage does not exceed the preset voltage. Or gradually reducing the derating coefficient according to the preset reduction value until the bus voltage does not exceed the preset voltage. Specifically, the selection can be performed according to actual conditions.
According to the method and the device for controlling the derating coefficient, when the first voltage exceeds the preset voltage and the duration of the first voltage exceeding the preset voltage exceeds the first preset duration, the derating coefficient is controlled to be reduced until the first voltage does not exceed the preset voltage.
And when the first voltage exceeds the preset voltage, but the duration of the first voltage exceeding the preset voltage does not exceed the first preset duration, maintaining the derating coefficient unchanged.
In the embodiment of the application, when the power grid is in a normal state, the derating coefficient is set to a default value, and when the power grid is in a high-voltage state, the derating coefficient can be controlled to be gradually reduced from the default value. Wherein the default value may be 1.
According to the embodiment of the application, when the power grid is in a high-voltage state, the derating coefficient is controlled to be reduced gradually so as to reduce the bus voltage, further reduce the active power output by the photovoltaic system and maintain the stability of the power grid and the stability of the photovoltaic system.
In some embodiments of the present application, after controlling the derating factor reduction, the control method may further include:
and if the power grid is recovered to a normal state from a high-voltage state, controlling the derating coefficient to be recovered to a default value.
The normal state is a working state that the power grid voltage is not less than the rated minimum voltage of the power grid and not more than the rated maximum voltage of the power grid.
After the derating coefficient is reduced, if the power grid is recovered to a normal state from a high-voltage state, the power grid voltage is recovered to a normal value, the grid-connected point voltage of the photovoltaic system and the power grid is recovered to the normal voltage from the high voltage, the voltage feedback value of the bus voltage loop is reduced, and the derating coefficient can be adjusted to be gradually increased to a default value at the moment so as to avoid the over-low bus voltage.
According to the embodiment of the application, after the power grid is restored to the normal state, the derating coefficient is adjusted to be restored to the default value, so that the fluctuation of the power grid can be avoided as much as possible, and the working reliability of the photovoltaic system and the working reliability of the power grid are ensured.
In some embodiments of the present application, "adjusting the derating coefficient according to the ratio of the first voltage and the second voltage" in S103 may include:
and when the ratio exceeds a preset ratio, controlling the derating coefficient to be reduced until the ratio does not exceed the preset ratio.
And when the ratio does not exceed the preset ratio, maintaining the derating coefficient unchanged.
When the grid voltage is less than the rated minimum voltage of the grid, the grid voltage is in a low-voltage state. At this time, if the ratio of the bus voltage to the grid voltage exceeds the preset ratio, the bus voltage is relatively too high, and at this time, the derating coefficient can be controlled to gradually decrease so as to regulate down the bus voltage until the ratio of the bus voltage to the grid voltage does not exceed the preset ratio, so as to control the active power output by the photovoltaic system not to exceed the second limiting power.
Alternatively, the derating factor may be gradually decreased linearly until the ratio of the bus voltage to the grid voltage does not exceed the preset ratio. Or gradually reducing the derating coefficient according to a preset reduction value until the ratio of the bus voltage to the grid voltage does not exceed the preset ratio. Specifically, the selection can be performed according to actual conditions.
According to the method and the device for controlling the derating coefficient, when the ratio of the first voltage to the second voltage exceeds the preset ratio, and the duration of the ratio of the first voltage to the second voltage exceeding the preset ratio exceeds the second preset duration, the derating coefficient is controlled to be reduced until the ratio of the first voltage to the second voltage does not exceed the preset ratio.
And when the first voltage exceeds the preset voltage, but the duration of the first voltage exceeding the preset voltage does not exceed the first preset duration, maintaining the derating coefficient unchanged.
According to the embodiment of the application, when the power grid is in a low-voltage state, the derating coefficient is gradually controlled to be reduced, so that the bus voltage is reduced, the active power output by the photovoltaic system is further reduced, and the stability of the power grid and the stability of the photovoltaic system are maintained.
In some embodiments of the present application, after controlling the derating factor reduction, the control method further comprises:
and if the power grid is recovered to a normal state from a low-voltage state, controlling the derating coefficient to be recovered to a default value.
After the derating coefficient is reduced, if the power grid is recovered to a normal state from a low-voltage state, the derating coefficient can be adjusted to be gradually increased to a default value so as to ensure that the ratio of the bus voltage to the power grid voltage does not exceed a preset ratio.
According to the embodiment of the application, after the power grid is restored to the normal state, the derating coefficient is adjusted to be restored to the default value, so that the fluctuation of the power grid can be avoided as much as possible, and the working reliability of the photovoltaic system and the working reliability of the power grid are ensured.
In some embodiments of the present application, the "determining that the power grid is in the high-voltage state or the low-voltage state" in S101 may include:
and when an active power request of the power grid is received, acquiring the power grid voltage, and judging whether the power grid is in a high-voltage state or a low-voltage state according to the power grid voltage.
And when the active power request of the power grid is not received, the power grid voltage is not acquired, and the judgment of the working state of the power grid is not carried out.
When the power grid needs to be supported by the active power of the photovoltaic system, an active request can be sent to the photovoltaic system. When the photovoltaic system receives the active request, the voltage of the power grid can be obtained, and the current working state of the power grid can be determined.
And when the power grid voltage is greater than the rated maximum voltage of the power grid, determining that the power grid is in a high-voltage state. And when the voltage of the power grid is smaller than the rated minimum voltage of the power grid, determining that the power grid is in a low-voltage state.
According to the embodiment of the application, when the active request of the power grid is received, corresponding control logic is executed again so as to maintain the stability of the power grid and the photovoltaic system and avoid the mutual influence of the photovoltaic system and the power grid under the condition of weak power grid.
It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic of each process, and should not limit the implementation process of the embodiment of the present application in any way.
The following are device embodiments of the present application, for details not described in detail therein, reference may be made to the corresponding method embodiments described above.
Fig. 3 shows a schematic structural diagram of a control device provided in an embodiment of the present application, and for convenience of explanation, only the portions relevant to the embodiment of the present application are shown, which are described in detail below:
as shown in fig. 3, the control device 20 is applied to a photovoltaic system connected to a power grid, and includes:
the judging module 201 is configured to judge whether the power grid is in a high-voltage state or a low-voltage state, where the high-voltage state is a working state in which the power grid voltage is greater than the rated maximum voltage of the power grid, and the low-voltage state is a working state in which the power grid voltage is less than the rated minimum voltage of the power grid;
the first control module 202 is configured to adjust a derating coefficient according to a first voltage when the power grid is in a high-voltage state, so as to control active power output by the photovoltaic system not to exceed limiting power, where the first voltage is a bus voltage of the photovoltaic system, the derating coefficient is used to adjust a voltage feedback value of a bus voltage loop, and the voltage feedback value decreases with a decrease of the derating coefficient;
the second control module 203 is configured to adjust the derating coefficient according to a ratio of the first voltage to the second voltage when the power grid is in a low-voltage state, so as to control the active power output by the photovoltaic system not to exceed the limit power, where the second voltage is the power grid voltage. May include:
in some embodiments of the present application, the first control module 202 is further configured to control the derating coefficient to decrease when the first voltage exceeds the preset voltage until the first voltage does not exceed the preset voltage.
In some embodiments of the present application, the control device 20 may further include:
and the third control module is used for controlling the derating coefficient to be restored to a default value if the power grid is restored to a normal state from a high-voltage state after the derating coefficient is controlled to be reduced.
In some embodiments of the present application, the second control module 203 is further configured to control the derating coefficient to decrease when the ratio exceeds a preset ratio until the ratio does not exceed the preset ratio.
In some embodiments of the present application, the control device 20 may further include:
and the fourth control module is used for controlling the derating coefficient to be restored to a default value if the power grid is restored to a normal state from a low-voltage state after the derating coefficient is controlled to be reduced.
In some embodiments of the present application, the determining module 201 is further configured to obtain the power grid voltage when the active request of the power grid is received, and determine that the power grid is in a high-voltage state or a low-voltage state according to the power grid voltage.
Fig. 4 is a schematic diagram of a controller provided in an embodiment of the present application. As shown in fig. 4, the controller 30 of this embodiment includes: a processor 300 and a memory 301, the memory 301 having stored therein a computer program 302 executable on the processor 300. The steps of the various control method embodiments described above are implemented by processor 300 when executing computer program 302. Alternatively, the processor 300, when executing the computer program 302, performs the functions of the modules/units of the apparatus embodiments described above.
By way of example, the computer program 302 may be partitioned into one or more modules/units, which are stored in the memory 301 and executed by the processor 300 to complete the present application. One or more of the modules/units may be a series of computer program instruction segments capable of performing particular functions to describe the execution of the computer program 302 in the controller 30.
The controller 30 may be a further controller of the photovoltaic system or a controller of the inverter. The controller 30 may include, but is not limited to, a processor 300, a memory 301. It will be appreciated by those skilled in the art that fig. 4 is merely an example of the controller 30 and is not meant to be limiting of the controller 30, and may include more or fewer components than shown, or may combine certain components, or different components, e.g., the controller may further include input-output devices, network access devices, buses, etc.
The processor 300 may be a central processing unit (Central Processing Unit, CPU), but may also be other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 301 may be an internal storage unit of the controller 30, such as a hard disk or a memory of the controller 30. The memory 301 may also be an external storage device of the controller 30, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card) or the like, which are provided on the controller 30. Further, the memory 301 may also include both an internal storage unit and an external storage device of the controller 30. The memory 301 is used to store computer programs and other programs and data required by the controller. The memory 301 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.
Embodiments of the present application also provide a photovoltaic system including a controller 30 as above.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the embodiments provided in this application, it should be understood that the disclosed apparatus/controller and method may be implemented in other ways. For example, the apparatus/controller embodiments described above are merely illustrative, e.g., the division of modules or units is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated modules/units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present application implements all or part of the flow of the method of the above embodiment, or may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, where the computer program, when executed by a processor, may implement the steps of each of the control method embodiments described above. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, executable files or in some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.

Claims (10)

1. A control method, characterized by being applied to a photovoltaic system connected to an electric grid, comprising:
judging whether the power grid is in a high-voltage state or a low-voltage state, wherein the high-voltage state is a working state that the power grid voltage is larger than the rated maximum voltage of the power grid, and the low-voltage state is a working state that the power grid voltage is smaller than the rated minimum voltage of the power grid;
when the power grid is in a high-voltage state, regulating a derating coefficient according to a first voltage so as to control the active power output by the photovoltaic system not to exceed a first limiting power, wherein the first voltage is the bus voltage of the photovoltaic system, the derating coefficient is used for regulating a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient;
when the power grid is in a low-voltage state, the derating coefficient is adjusted according to the ratio of the first voltage to the second voltage so as to control the active power output by the photovoltaic system not to exceed the second limiting power, wherein the second voltage is the power grid voltage.
2. The control method according to claim 1, wherein the adjusting the derating factor according to the first voltage includes:
and when the first voltage exceeds a preset voltage, controlling the derating coefficient to decrease until the first voltage does not exceed the preset voltage.
3. The control method according to claim 2, characterized in that after controlling the derating coefficient to decrease, the control method further comprises:
and if the power grid is recovered to a normal state from a high-voltage state, controlling the derating coefficient to recover to a default value.
4. The control method according to claim 1, wherein the adjusting the derating coefficient according to the ratio of the first voltage and the second voltage includes:
and when the ratio exceeds a preset ratio, controlling the derating coefficient to be reduced until the ratio does not exceed the preset ratio.
5. The control method according to claim 4, characterized in that after controlling the derating coefficient to decrease, the control method further comprises:
and if the power grid is recovered to a normal state from a low-voltage state, controlling the derating coefficient to recover to a default value.
6. The control method according to any one of claims 1 to 5, characterized in that the determining that the power grid is in a high-voltage state or a low-voltage state includes:
and when the active request of the power grid is received, acquiring the power grid voltage, and judging whether the power grid is in a high-voltage state or a low-voltage state according to the power grid voltage.
7. A control device for use in a photovoltaic system connected to an electrical grid, the control device comprising:
the judging module is used for judging whether the power grid is in a high-voltage state or a low-voltage state, wherein the high-voltage state is a working state that the power grid voltage is larger than the rated maximum voltage of the power grid, and the low-voltage state is a working state that the power grid voltage is smaller than the rated minimum voltage of the power grid;
the first control module is used for adjusting a derating coefficient according to a first voltage when the power grid is in a high-voltage state so as to control the active power output by the photovoltaic system not to exceed the limit power, wherein the first voltage is the bus voltage of the photovoltaic system, the derating coefficient is used for adjusting a voltage feedback value of a bus voltage loop, and the voltage feedback value is reduced along with the reduction of the derating coefficient;
and the second control module is used for adjusting the derating coefficient according to the ratio of the first voltage to the second voltage when the power grid is in a low-voltage state so as to control the active power output by the photovoltaic system not to exceed the limit power, wherein the second voltage is the power grid voltage.
8. A controller comprising a memory and a processor, in which a computer program is stored which is executable on the processor, characterized in that the processor, when executing the computer program, carries out the steps of the control method according to any one of the preceding claims 1 to 6.
9. A photovoltaic system comprising the controller of claim 8.
10. A computer-readable storage medium storing a computer program, characterized in that the computer program, when executed by a processor, implements the steps of the control method according to any one of the preceding claims 1 to 6.
CN202311570692.9A 2023-11-23 2023-11-23 Control method, controller and photovoltaic system Pending CN117674255A (en)

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