CN111756046B - Bus voltage control method, controller and photovoltaic energy storage conversion system - Google Patents
Bus voltage control method, controller and photovoltaic energy storage conversion system Download PDFInfo
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- CN111756046B CN111756046B CN202010743648.3A CN202010743648A CN111756046B CN 111756046 B CN111756046 B CN 111756046B CN 202010743648 A CN202010743648 A CN 202010743648A CN 111756046 B CN111756046 B CN 111756046B
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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
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
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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
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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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
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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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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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
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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
- Y02E70/00—Other energy conversion or management systems reducing GHG emissions
- Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
Abstract
The invention provides a bus voltage control method, a controller and a photovoltaic energy storage conversion system, which are applied to the technical field of photovoltaic power generation, wherein the method comprises the steps of firstly judging whether a photovoltaic module is connected into the photovoltaic energy storage conversion system or not under the condition of meeting a preset bus voltage control condition, and controlling an energy storage battery to stop working if the photovoltaic module is connected into the photovoltaic energy storage conversion system, so that the photovoltaic module stabilizes direct current bus voltage; if photovoltaic module does not have photovoltaic energy storage transform system, then stop the charging process of energy storage battery with presetting the parameter threshold as the target value, because it is given based on photovoltaic energy storage transform system's sampling error to preset the parameter threshold, when stopping the charging process of energy storage battery according to presetting the parameter threshold, can ensure that energy storage battery's charging current more than or equal to 0, the negative value condition can not appear, thereby avoid energy storage battery to last to direct current bus charging, more can not cause the problem that bus voltage rises, improve photovoltaic energy storage transform system's stability.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to a bus voltage control method, a controller and a photovoltaic energy storage conversion system.
Background
The photovoltaic energy storage conversion system is a power distribution subsystem connected with a distributed power supply, can independently and normally operate, and maintains the power supply of all or part of important electric equipment. As shown in fig. 1 and fig. 2, in practical application, a photovoltaic energy storage conversion system has two output modes of direct current output and alternating current output, wherein when the direct current output mode is adopted, a photovoltaic module and an energy storage battery are respectively connected with a direct current bus through respective corresponding DC/DC converters and are connected with a public power grid through the direct current bus; when an alternating current output mode is adopted, the photovoltaic module and the energy storage battery are firstly connected with a direct current bus through the corresponding DC/DC converter respectively, then are connected with the direct current side of the DC/AC converter through the direct current bus, and finally are input into a public power grid after being inverted by the DC/AC converter.
As can be seen from fig. 1 and 2, no matter what output mode is adopted by the photovoltaic energy storage conversion system, a dc bus is arranged in the system. For a photovoltaic energy storage conversion System with a direct current bus, if the output power is limited to zero by a BMS (Battery Management System) in a grid-connected operation state, or if an external load is empty and the charging power allowed by an energy storage Battery in the System is zero in an off-grid operation state, the charging current of a DC/DC converter connected to the energy storage Battery and in a working state, that is, the charging current setting value of the energy storage Battery, is gradually reduced to a zero value.
However, in practical applications, due to the existence of current sampling errors, such a situation often occurs: the charging current of the energy storage battery is actually reduced to a zero value, but the current sampling data is larger than the zero value, in order to stop charging the energy storage battery, the controller can continuously reduce the current of the DC/DC converter, so that the current flowing through the DC/DC converter becomes a negative value, for the energy storage battery, the DC bus is actually discharged by a small current, and because the load on the output side of the DC bus is zero at the moment, the energy storage battery can continuously charge the voltage of the DC bus high, and finally the overvoltage protection of the DC bus is triggered mistakenly.
Disclosure of Invention
The invention provides a bus voltage control method, a controller and a photovoltaic energy storage conversion system, which are used for realizing stable control of direct current bus voltage in the photovoltaic energy storage conversion system, avoiding mistaken triggering of overvoltage protection and improving stability of the photovoltaic energy storage conversion system.
In order to achieve the purpose, the technical scheme provided by the application is as follows:
in a first aspect, the present invention provides a bus voltage control method, including:
under the condition that the preset bus voltage control condition is met, judging whether a photovoltaic assembly in the photovoltaic energy storage conversion system is connected to the photovoltaic energy storage conversion system or not;
if the photovoltaic module is connected to the photovoltaic energy storage conversion system, controlling an energy storage battery of the photovoltaic energy storage conversion system to stop working;
and if the photovoltaic module is not connected with the photovoltaic energy storage conversion system, stopping the charging process of the energy storage battery by taking a preset parameter threshold value as a target value, wherein the preset parameter threshold value is given based on the sampling error of the photovoltaic energy storage conversion system.
Optionally, after the energy storage battery of the photovoltaic energy storage conversion system is controlled to stop working, the method further includes:
acquiring the bus voltage of a direct current bus;
and if the bus voltage is less than or equal to a first preset voltage threshold value, controlling the energy storage battery to start working.
Optionally, the preset parameter threshold is greater than or equal to the sampling error.
Optionally, the preset parameter threshold includes a preset charging current threshold or a preset charging power threshold.
Optionally, the stopping the charging process of the energy storage battery with the preset parameter threshold as the target value includes:
determining a charging and discharging current limiting value of the energy storage battery;
if the charging and discharging current limiting value is larger than or equal to the preset charging current threshold value, reducing the charging current of the energy storage battery according to the charging and discharging current limiting value;
and if the charging and discharging current limiting value is smaller than the preset charging current threshold value, reducing the charging current of the energy storage battery by taking the preset charging current threshold value as a target value.
Optionally, the determining the charge-discharge current limiting value of the energy storage battery includes:
obtaining the maximum allowable charging current value MCCV of the energy storage battery;
and determining the charging and discharging current limiting value of the energy storage battery according to the magnitude relation between the MCCV and the rated current of the designated hardware in the photovoltaic energy storage conversion system.
Optionally, the determining whether a photovoltaic module in the photovoltaic energy storage conversion system is connected to the photovoltaic energy storage conversion system includes:
acquiring output voltage and output power of a photovoltaic module in a photovoltaic energy storage conversion system;
if the output voltage is smaller than a second preset voltage threshold value, or the output power is zero, judging that the photovoltaic module is not connected to the photovoltaic energy storage conversion system;
and if the output voltage is not less than the second preset voltage threshold value and the output power is not zero, judging that the photovoltaic module is connected to the photovoltaic energy storage conversion system.
Optionally, the controlling the energy storage battery of the photovoltaic energy storage conversion system to stop working includes:
stopping the operation process of a charge and discharge control loop of an energy storage battery in the photovoltaic energy storage conversion system;
and controlling a DC/DC converter connected with the energy storage battery to stop working.
Optionally, the controlling the energy storage battery to start operating includes:
starting a charge and discharge control loop operation process of an energy storage battery in the photovoltaic energy storage conversion system;
and controlling a DC/DC converter connected with the energy storage battery to start to work.
Optionally, the preset bus voltage control condition includes: the allowable maximum charging current value MCCV sent by the battery management system is zero, and the output power of the photovoltaic energy storage conversion system is zero.
Optionally, the working condition that the output power of the photovoltaic energy storage conversion system is zero includes:
when the photovoltaic energy storage conversion system operates in a grid-connected state, the output power of the photovoltaic energy storage conversion system is zero;
when the photovoltaic energy storage conversion system operates in an off-grid state, the photovoltaic energy storage conversion system is in no-load state, and the charging power allowed by the energy storage battery is zero.
In a second aspect, the present invention provides a controller comprising: a memory and a processor; the memory stores a program suitable for the processor to execute, so as to implement the bus voltage control method according to any one of the first aspect of the present invention.
In a third aspect, the present invention provides a photovoltaic energy storage conversion system, including: at least one photovoltaic module, at least one energy storage cell, a first DC/DC converter, a second DC/DC converter, a DC bus, and a controller according to the second aspect of the invention, wherein,
each photovoltaic module is connected with the direct current bus through the first DC/DC converter;
each energy storage battery is connected with the direct current bus through the second DC/DC converter;
the controller is respectively connected with the control ends of the photovoltaic assemblies, the energy storage batteries, the first DC/DC converter and the second DC/DC converter.
Optionally, the photovoltaic energy storage conversion system provided by the second aspect of the present invention further includes: a DC/AC converter, wherein,
the direct current side of the DC/AC converter is connected with the direct current bus;
the AC side of the DC/AC converter is connected with a public power grid or an electric load.
According to the bus voltage control method provided by the invention, under the condition that a preset bus voltage control condition is met, whether a photovoltaic module is connected into a photovoltaic energy storage conversion system or not is judged firstly, if the photovoltaic module is connected into the photovoltaic energy storage conversion system, an energy storage battery is controlled to stop working, the photovoltaic module stabilizes the voltage of a direct current bus, and under the working condition, the energy storage battery stops working, so that the direct current bus cannot be charged; if photovoltaic module does not have photovoltaic energy storage transform system, then stop the charging process of energy storage battery with presetting the parameter threshold as the target value, under this kind of operating mode, because presetting the parameter threshold and being based on photovoltaic energy storage transform system's sampling error is given, when stopping the charging process of energy storage battery according to presetting the parameter threshold, can ensure that energy storage battery's charging current more than or equal to 0, the negative value condition can not appear to avoid energy storage battery to continuously charge to the direct current bus, more can not cause the problem that busbar voltage rises. Therefore, the bus voltage control method provided by the invention can realize stable control of the DC bus voltage in the photovoltaic energy storage conversion system, avoid mistaken triggering of overvoltage protection and improve the stability of the photovoltaic energy storage conversion system.
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. 1 is a system block diagram of a photovoltaic energy storage conversion system outputting alternating current in the prior art;
FIG. 2 is a system block diagram of a photovoltaic energy storage conversion system outputting DC power in the prior art;
FIG. 3 is a flow chart of a bus voltage control method provided by the present application;
FIG. 4 is a functional diagram of a charge and discharge control loop of an energy storage battery according to the prior art;
fig. 5 is a block diagram of a controller according to 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.
Referring to fig. 3, fig. 3 is a flowchart of a bus voltage control method according to an embodiment of the present invention, and the bus voltage control method according to the present invention is mainly used for controlling a bus voltage of a dc bus in a photovoltaic energy storage conversion system to avoid triggering an overvoltage protection due to an excessively high bus voltage, the method can be applied to a controller, which can be a controller independent from the photovoltaic energy storage conversion system, or a controller included in the photovoltaic energy storage conversion system itself, such as a DC/DC converter connected with the energy storage battery, or a controller in a DC/DC converter connected to the photovoltaic module can acquire various parameters described in the embodiments of the present invention, and the controller running a control program corresponding to the present invention is optional, and obviously, the controller may also be implemented by a server on the network side in some cases; referring to fig. 3, a bus voltage control method provided in an embodiment of the present invention may include:
s100, under the condition that the preset bus voltage control condition is met, whether the photovoltaic assembly is connected to the photovoltaic energy storage conversion system or not is judged, if not, S110 is executed, and if yes, S120 is executed.
As mentioned above, the photovoltaic energy storage conversion system includes two operation states of grid-connected operation and off-grid operation, if the photovoltaic energy storage conversion system is in the grid-connected operation state, the BMS limits the output power to zero; or, under the condition that the photovoltaic energy storage conversion system is in an off-grid running state, the external load is empty, and the charging power allowed by the energy storage battery in the system is zero, the charging current set value of the energy storage battery is gradually reduced to a zero value so as to stop charging the energy storage battery.
Optionally, based on the actual working process of the photovoltaic energy storage conversion system, the preset bus voltage control condition in the embodiment of the present invention may include: the MCCV value sent by the BMS, namely the maximum allowable charging current value is zero, and the output power of the photovoltaic energy storage conversion system is zero.
Further, to the operating mode that the output power of photovoltaic energy storage conversion system is zero, can specifically divide according to the running state of photovoltaic energy storage conversion system: when the photovoltaic energy storage conversion system operates in a grid-connected state, the output power of the photovoltaic energy storage conversion system is zero; when the photovoltaic energy storage conversion system operates in an off-grid state, the photovoltaic energy storage conversion system is in no-load, and the charging power allowed by the energy storage battery is zero.
When the operating state of the photovoltaic energy storage conversion system meets the above conditions, it can be determined that overvoltage risk exists on the direct current bus in the photovoltaic energy storage conversion system, and bus voltage of the direct current bus needs to be controlled. In the embodiment of the invention, for the control process of the direct current bus voltage, different control measures are taken according to whether the photovoltaic battery is connected to the photovoltaic energy storage conversion system, so that under the condition of meeting the control condition of the preset bus voltage, whether a photovoltaic assembly in the photovoltaic energy storage conversion system is connected to the photovoltaic energy storage conversion system is judged firstly.
It should be noted that, in the embodiment of the present invention, whether the photovoltaic module is connected to the photovoltaic energy storage conversion system or not is not only a judgment on a physical connection between the photovoltaic module and the photovoltaic energy storage conversion system (specifically, a dc bus), but also a judgment on whether the photovoltaic module inputs power to the photovoltaic energy storage conversion system or not and on a premise that the photovoltaic module and the photovoltaic energy storage conversion system have a reliable physical connection.
Specifically, if the photovoltaic module and the photovoltaic energy storage conversion system are not physically connected and are disconnected, it can be determined without doubt that the photovoltaic module is not connected to the photovoltaic energy storage conversion system. If stable physical connection is established between the photovoltaic module and the photovoltaic energy storage conversion system, the electrical connection relationship between the photovoltaic module and the photovoltaic energy storage conversion system needs to be further checked.
Optionally, the judgment can be performed based on the output condition of the photovoltaic module. Acquiring the output voltage and the output power of the photovoltaic module, and if the output voltage of the photovoltaic module is smaller than a second preset voltage threshold value or the output power of the photovoltaic module is zero, judging that the photovoltaic module is not connected with the photovoltaic energy storage conversion system under the two conditions; on the contrary, if the output voltage of the photovoltaic module is not less than the second preset voltage threshold value and the output power is not zero, the photovoltaic module is judged to be connected to the photovoltaic energy storage conversion system.
The method for judging whether the physical connection is established between the photovoltaic module and the photovoltaic energy storage conversion system can be realized based on the prior art, and the method is not limited in the invention.
And S110, stopping the charging process of the energy storage battery by taking a preset parameter threshold value as a target value.
Under the condition that the photovoltaic module is not connected with the photovoltaic energy storage conversion system, the control method provided by the invention stops the charging process of the energy storage battery by using the non-target value of the preset parameter threshold.
As described above, in the charging control method in the prior art, under the condition that the preset bus voltage control condition is satisfied, the charging process of the energy storage battery is controlled by using the charging current close to 0A as the target value, when the actual charging current is reduced to 0A, the charging current obtained by the controller is still larger than zero due to the existence of the sampling error, and the controller will continue to reduce the charging current of the energy storage battery, so that the charging current becomes a negative value.
Based on the above situation, the preset parameter threshold mentioned in the embodiment of the present invention is given based on the sampling error of the photovoltaic energy storage conversion system, and specifically, the preset parameter threshold is greater than or equal to the sampling error of the photovoltaic energy storage system. When the controller executing the control method provided by the embodiment of the invention controls the energy storage battery to be charged, the charging process of the energy storage battery is controlled by taking the preset parameter threshold as a target value. Optionally, the preset parameter threshold mentioned in the embodiment of the present invention may be a preset charging current threshold, or a preset charging power threshold, that is, the charging process may be controlled from two aspects of charging current and charging power.
Optionally, taking the preset charging current threshold as an example, in an actual control process, the controller may receive the MCCV of the energy storage battery sent by the BMS, and meanwhile, a rated current of designated hardware in the system needs to be considered comprehensively, and it is conceivable that the designated hardware mentioned in the embodiment of the present invention refers to hardware related to a charging and discharging process of the energy storage battery.
The controller firstly determines the charging and discharging current limiting value of the energy storage battery according to the magnitude relation between the obtained MCCV and the rated current of the appointed hardware. Specifically, if the obtained MCCV is larger than the rated current of the specified hardware, the charging and discharging current limiting value is set according to the rated current of the specified hardware, and conversely, if the obtained MCCV is not larger than the rated current of the specified hardware, the charging and discharging current limiting value of the energy storage battery is set according to the obtained MCCV. In most cases, the MCCV is no greater than the current rating of the designated hardware, and the controller sets the charge and discharge current limit values directly from the resulting MCCV.
It should be noted that the charging and discharging current limiting value is the maximum value of the charging and discharging current in the charging and discharging process of the energy storage battery, but is not the actual charging and discharging current value, that is, is not the charging and discharging current set value, and the charging and discharging current set value is selected according to the charging and discharging current limiting value.
Further, if the charging and discharging current amplitude limit value determined through the steps is larger than or equal to the preset charging current threshold value, the charging current of the energy storage battery is still larger, and the charging current of the energy storage battery can be reduced according to the charging and discharging current amplitude limit value; on the contrary, if the charging and discharging current limiting value determined through the foregoing steps is smaller than the preset charging current threshold value, since the charging and discharging current limiting value is set with MCCV as a reference, MCCV in this case is already close to 0A or equal to 0A, and if the charging process of the energy storage battery is continuously controlled with the charging and discharging current limiting value as a target value, a problem that the charging process is converted into the discharging process in the prior art may occur, therefore, in this case, the control method reduces the charging current of the energy storage battery with the preset charging current threshold value as the target value, and the preset charging current threshold value is greater than or equal to the sampling error, and the situation that the charging current is reduced to a negative value with the preset charging current threshold value as the target value may be avoided, thereby avoiding charging the bus voltage of the dc bus high.
It is conceivable that, because the photovoltaic module is not connected to the photovoltaic energy storage conversion system under the condition, no power supply charges the energy storage battery, and the actual charging current of the energy storage battery is not greater than the MCCV, the control requirement in the prior art is met.
And S120, controlling the energy storage battery of the photovoltaic energy storage conversion system to stop working.
Under the condition that the photovoltaic assembly is connected to the photovoltaic energy storage conversion system, the energy storage battery needs to be controlled to stop working, and the photovoltaic assembly provides power, so that the voltage of the direct current bus is kept stable.
Specifically, in the process of stopping the energy storage battery, the operation process of a charge and discharge control loop of the energy storage battery in the photovoltaic energy storage conversion system needs to be stopped, and meanwhile, a DC/DC converter connected with the energy storage battery needs to be controlled to stop working. Referring to fig. 4, fig. 4 is a functional schematic diagram of a charge and discharge control loop of an energy storage battery in the prior art, and for a specific control process of the charge and discharge control loop and a stop and start process of the charge and discharge control loop, the present invention can be implemented with reference to the prior art, which is not limited in this respect.
And S130, acquiring the bus voltage of the direct current bus.
Under the condition that the photovoltaic module is connected into the photovoltaic energy storage conversion system, if the photovoltaic energy storage conversion system is connected with an electric load, and the required power of the electric load is greater than the total power which can be provided by the photovoltaic module, the direct current bus can be forced to discharge so as to make up the deficiency of the power of the photovoltaic module, and along with the discharge of the direct current bus, the bus voltage can be obviously reduced.
Therefore, under the condition that the photovoltaic energy storage conversion system is connected to the electric load, the bus voltage of the direct current bus can be obtained, whether the energy storage battery is connected or not is judged according to the change condition of the bus voltage, and the energy storage battery and the photovoltaic module provide required power for the electric load together.
S140, judging whether the bus voltage is smaller than or equal to a first preset voltage threshold, if so, executing S150, and if not, returning to execute S130.
After the bus voltage is obtained, judging whether the bus voltage is smaller than or equal to a first preset voltage threshold, if so, executing S150; on the contrary, if the bus voltage is greater than the first preset voltage threshold, the process returns to step S130, and continues to collect the bus voltage of the dc bus.
It should be noted that the first preset voltage threshold mentioned in the embodiment of the present invention may be set according to the output power of the photovoltaic module in the photovoltaic energy storage conversion system and the actual power consumption condition of the power load connected to the conversion system, and as long as the value meeting the power supply stability is optional, the specific value of the first preset voltage threshold is not limited in the present invention.
And S150, controlling the energy storage battery to start working.
Referring to the process of controlling the energy storage battery to stop working, when the energy storage battery is controlled to start working, the operation process of a charge and discharge control loop of the energy storage battery needs to be started, and meanwhile, a DC/DC converter connected with the energy storage battery is controlled to start working. After the energy storage battery starts to work, the energy storage battery and the photovoltaic module supply power to the power load together, and the power demand of the load is met.
In summary, the bus voltage control method provided in the embodiments of the present invention adopts different bus voltage control methods according to whether the photovoltaic module is connected to the photovoltaic energy storage conversion system, and if the photovoltaic module is not connected to the photovoltaic energy storage conversion system, the charging process of the energy storage battery is stopped with the preset parameter threshold as the target value. And if the photovoltaic module is connected to the photovoltaic energy storage conversion system, the energy storage battery is controlled to stop working, and the photovoltaic module stabilizes the voltage of the direct current bus. Therefore, the bus voltage control method provided by the invention can realize stable control of the DC bus voltage in the photovoltaic energy storage conversion system, avoid mistaken triggering of overvoltage protection and improve the stability of the photovoltaic energy storage conversion system.
Further, under the condition that the photovoltaic module is connected to the photovoltaic energy storage conversion system, once the bus voltage is reduced because the photovoltaic module supplies power to the power utilization load, the energy storage battery can be immediately started by the control method, the power utilization load is supplied with power by the energy storage battery and the photovoltaic module together, the power utilization requirement of the power utilization load can be timely met, and the problem of bus voltage fluctuation can be effectively solved.
Fig. 5 is a block diagram of a controller according to an embodiment of the present invention, and as shown in fig. 5, the block diagram may include: at least one processor 100, at least one communication interface 200, at least one memory 300, and at least one communication bus 400;
in the embodiment of the present invention, the number of the processor 100, the communication interface 200, the memory 300, and the communication bus 400 is at least one, and the processor 100, the communication interface 200, and the memory 300 complete the communication with each other through the communication bus 400; it is clear that the communication connections shown by the processor 100, the communication interface 200, the memory 300 and the communication bus 400 shown in fig. 5 are merely optional;
optionally, the communication interface 200 may be an interface of a communication module, such as an interface of a GSM module;
the processor 100 may be a central processing unit CPU or an application Specific Integrated circuit asic or one or more Integrated circuits configured to implement embodiments of the present invention.
The memory 300, which stores application programs, may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.
The processor 100 is specifically configured to execute an application program in the memory to implement any of the embodiments of the bus voltage control method described above.
Optionally, the present invention further provides a photovoltaic energy storage conversion system, including: at least one photovoltaic module, at least one energy storage cell, a first DC/DC converter, a second DC/DC converter, a DC bus, and a controller provided in the embodiment shown in fig. 5, wherein,
each photovoltaic module is connected with the direct current bus through the first DC/DC converter;
each energy storage battery is connected with the direct current bus through the second DC/DC converter;
the controller is respectively connected with the control ends of the photovoltaic assemblies, the energy storage batteries, the first DC/DC converter and the second DC/DC converter.
For the photovoltaic energy storage conversion system provided by the above embodiment, a specific system framework thereof can be shown with reference to fig. 2.
Optionally, the invention provides another photovoltaic energy storage conversion system, and a system framework of the system can be shown in fig. 1. On the basis of the above embodiment, the system further includes: a DC/AC converter, wherein,
the direct current side of the DC/AC converter is connected with the direct current bus;
the AC side of the DC/AC converter is connected with a public power grid or an electric load.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are 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.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. 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 invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. 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 invention. Thus, the present invention 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 (12)
1. A bus voltage control method, comprising:
under the condition that the preset bus voltage control condition is met, judging whether a photovoltaic assembly in the photovoltaic energy storage conversion system is connected to the photovoltaic energy storage conversion system or not;
wherein the preset bus voltage control conditions include: the maximum allowable charging current value MCCV sent by the battery management system is zero, and the output power of the photovoltaic energy storage conversion system is zero;
if the photovoltaic module is connected to the photovoltaic energy storage conversion system, controlling an energy storage battery of the photovoltaic energy storage conversion system to stop working;
and if the photovoltaic assembly is not connected with the photovoltaic energy storage conversion system, stopping the charging process of the energy storage battery by taking a preset parameter threshold value as a target value, wherein the preset parameter threshold value is greater than or equal to the sampling error of the photovoltaic energy storage system.
2. The bus voltage control method according to claim 1, further comprising, after the controlling the energy storage battery of the photovoltaic energy storage conversion system to stop operating:
acquiring the bus voltage of a direct current bus;
and if the bus voltage is less than or equal to a first preset voltage threshold value, controlling the energy storage battery to start working.
3. The bus voltage control method according to claim 1, wherein the preset parameter threshold comprises a preset charging current threshold or a preset charging power threshold.
4. The bus voltage control method according to claim 3, wherein the stopping of the charging process of the energy storage battery with the preset parameter threshold as the target value comprises:
determining a charging and discharging current limiting value of the energy storage battery;
if the charging and discharging current limiting value is larger than or equal to the preset charging current threshold value, reducing the charging current of the energy storage battery according to the charging and discharging current limiting value;
and if the charging and discharging current limiting value is smaller than the preset charging current threshold value, reducing the charging current of the energy storage battery by taking the preset charging current threshold value as a target value.
5. The bus voltage control method according to claim 4, wherein the determining the charge-discharge current limiting value of the energy storage battery comprises:
obtaining the maximum allowable charging current value MCCV of the energy storage battery;
and determining the charging and discharging current limiting value of the energy storage battery according to the magnitude relation between the MCCV and the rated current of the designated hardware in the photovoltaic energy storage conversion system.
6. The bus voltage control method according to claim 1, wherein the determining whether a photovoltaic module in a photovoltaic energy storage conversion system is connected to the photovoltaic energy storage conversion system comprises:
acquiring output voltage and output power of a photovoltaic module in a photovoltaic energy storage conversion system;
if the output voltage is smaller than a second preset voltage threshold value, or the output power is zero, judging that the photovoltaic module is not connected to the photovoltaic energy storage conversion system;
and if the output voltage is not less than the second preset voltage threshold value and the output power is not zero, judging that the photovoltaic module is connected to the photovoltaic energy storage conversion system.
7. The bus voltage control method according to claim 1, wherein the controlling of the energy storage battery of the photovoltaic energy storage conversion system to stop working comprises:
stopping the operation process of a charge and discharge control loop of an energy storage battery in the photovoltaic energy storage conversion system;
and controlling a DC/DC converter connected with the energy storage battery to stop working.
8. The bus bar voltage control method according to claim 2, wherein the controlling the energy storage battery to start operating comprises:
starting a charge and discharge control loop operation process of an energy storage battery in the photovoltaic energy storage conversion system;
and controlling a DC/DC converter connected with the energy storage battery to start to work.
9. The bus voltage control method according to claim 1, wherein the working condition that the output power of the photovoltaic energy storage conversion system is zero comprises:
when the photovoltaic energy storage conversion system operates in a grid-connected state, the output power of the photovoltaic energy storage conversion system is zero;
when the photovoltaic energy storage conversion system operates in an off-grid state, the photovoltaic energy storage conversion system is in no-load state, and the charging power allowed by the energy storage battery is zero.
10. A controller, comprising: a memory and a processor; the memory stores a program adapted to be executed by the processor to implement the bus voltage control method according to any one of claims 1 to 9.
11. A photovoltaic energy storage conversion system, comprising: at least one photovoltaic module, at least one energy storage cell, a first DC/DC converter, a second DC/DC converter, a DC bus, and the controller of claim 10,
each photovoltaic module is connected with the direct current bus through the first DC/DC converter;
each energy storage battery is connected with the direct current bus through the second DC/DC converter;
the controller is respectively connected with the control ends of the photovoltaic assemblies, the energy storage batteries, the first DC/DC converter and the second DC/DC converter.
12. The photovoltaic energy storage conversion system according to claim 11, further comprising: a DC/AC converter, wherein,
the direct current side of the DC/AC converter is connected with the direct current bus;
the AC side of the DC/AC converter is connected with a public power grid or an electric load.
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| CN112701753B (en) * | 2020-12-23 | 2024-04-12 | 阳光电源股份有限公司 | Charging and discharging control method and energy storage system |
| CN113067547B (en) * | 2021-03-16 | 2022-07-12 | 阳光电源股份有限公司 | Monitoring device, monitoring method of photovoltaic string and readable storage medium |
| CN112994105A (en) * | 2021-03-25 | 2021-06-18 | 华为技术有限公司 | Photovoltaic power generation system, power control device and energy storage system |
| CN113206534A (en) * | 2021-06-08 | 2021-08-03 | 阳光电源股份有限公司 | Energy storage system power control method, controller and energy storage system |
| JP7374231B2 (en) * | 2021-07-29 | 2023-11-06 | 寧徳時代新能源科技股▲分▼有限公司 | Charging and discharging devices, battery charging and discharging methods, and charging and discharging systems |
| CN114447993B (en) * | 2022-04-08 | 2022-07-29 | 深圳市首航新能源股份有限公司 | Power control method, device, controller and optical storage system |
| CN114899913B (en) * | 2022-05-23 | 2023-12-12 | 浙江艾罗网络能源技术股份有限公司 | Battery charging and discharging current control method in off-grid mode of hybrid energy storage inverter |
| CN115001082B (en) * | 2022-06-01 | 2023-10-31 | 浙江艾罗网络能源技术股份有限公司 | Charging and discharging power balance distribution control method for hybrid energy storage inverter parallel operation system |
| CN115241926B (en) * | 2022-09-16 | 2023-02-28 | 深圳市首航新能源股份有限公司 | Bus voltage control method, bus balance control method and system |
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