WO2022198598A1 - 并离网模式切换的方法和储能系统 - Google Patents
并离网模式切换的方法和储能系统 Download PDFInfo
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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
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B17/00—Systems involving the use of models or simulators of said systems
- G05B17/02—Systems involving the use of models or simulators of said systems electric
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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
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
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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
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
- H02J3/241—The oscillation concerning frequency
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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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
Definitions
- the present application relates to the technical field of energy storage, and in particular, to a method and an energy storage system for switching between on-grid and off-grid modes.
- the energy storage system can be used to store the electricity generated by wind power or photovoltaic power generation, which can avoid the problem of abandoning wind and light.
- the energy storage system can switch from the grid-connected mode to the off-grid mode to supply power to the loads in the grid of the energy storage system.
- the inverter takes a long time to control the output voltage, there is a mechanical delay in disconnecting the on-grid mode switch, and there is a transmission delay in the state feedback of the on-grid mode switch, etc.
- the switching process is long, and voltage distortion or frequency distortion may occur during the switching process, which affects the power supply to the load.
- the embodiment of the present application discloses a method and an energy storage system for switching between on-grid and off-grid modes, which freezes the output frequency of the inverter to avoid the occurrence of frequency distortion events.
- the occurrence of voltage distortion events can be avoided, and the control efficiency of the inverter is improved compared with the direct control of the output voltage.
- the inverter After the inverter receives the switching instruction sent by the controller and determines that the output voltage of the inverter meets the preset range of the rated voltage, it switches to the voltage source mode to realize the switching between on-grid and off-grid modes, which improves the stability of the load operation. .
- an embodiment of the present application discloses an energy storage system.
- the energy storage system includes a controller, an inverter connected to the controller, an on-grid and off-grid mode switch, and a load connected to the on-grid and off-grid mode switch, wherein,
- the inverter In response to determining that the energy storage system is in an island state, the inverter sends an island state message to the controller, and freezes the output frequency of the inverter according to a preset frequency, and according to the inverter There is a negative correlation between the output voltage of the inverter and the apparent power of the inverter, and the output current of the inverter is controlled so that the output voltage of the inverter satisfies the preset rated voltage. scope;
- the controller is configured to send a disconnection instruction to the on-grid mode switch based on the island status message, where the disconnection instruction is used to instruct the on-grid and off-grid mode switch to correspond to the grid connected to the off-grid mode switch Disconnecting; in response to receiving a disconnection completion message from the on-grid mode switch, sending a switching instruction to the inverter, and the disconnection completion message is used to instruct the on-grid and off-grid mode switch to communicate with all the power grid is disconnected, and the switching instruction is used to instruct the inverter to switch to a voltage source mode;
- the inverter is further configured to switch to the voltage source mode in response to receiving the switching instruction and determining that the output voltage of the inverter meets a preset range of the rated voltage.
- the output frequency of the inverter is frozen according to the preset frequency, so as to avoid the occurrence of frequency distortion.
- the occurrence of voltage distortion events can be avoided, and the control efficiency of the inverter is improved compared with the direct control of the output voltage.
- the inverter is specifically configured to, according to a first correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated, perform a The output current of the inverter is controlled to obtain the first stable output voltage of the inverter and the first apparent power corresponding to the first stable output voltage, and the variation range of the first stable output voltage is less than or equal to the the preset range; according to the second correlation relationship that is positively correlated between the output voltage of the inverter and the apparent power of the load, and the magnitude relationship between the first stable output voltage and the rated voltage
- the first correlation relationship is adjusted to obtain a third correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated; according to the third correlation relationship and the rated voltage
- the output current of the inverter is controlled so that the output voltage of the inverter satisfies the preset range of the rated voltage.
- the first correlation between the output voltage of the inverter and the apparent power of the inverter is adjusted to obtain The third correlation relationship, so that the output current of the inverter is controlled according to the third correlation relationship and the rated voltage, the efficiency and accuracy of the control can be improved, and the stability of the load operation can be further improved.
- the inverter is specifically configured to adjust the first correlation relationship according to the magnitude relationship between the first stable output voltage and the rated voltage to obtain the output of the inverter a fourth correlation relationship in which the voltage and the apparent power of the inverter are negatively correlated; the output current of the inverter is controlled according to the fourth correlation relationship, and the second correlation relationship of the inverter is obtained.
- the stable output voltage and the second apparent power corresponding to the second stable output voltage, and the variation range of the second stable output voltage is less than or equal to the preset range; according to the first stable output voltage, the first stable output voltage an apparent power, the second stable output voltage and the second apparent power to obtain a second correlation relationship in which the output voltage of the inverter and the apparent power of the load are positively correlated; according to the The second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage are adjusted to the fourth correlation relationship to obtain the output voltage of the inverter and the apparent voltage of the inverter.
- the third relationship is a negative correlation between the powers.
- the fourth correlation relationship obtained by adjusting the first correlation relationship through the magnitude relationship between the first stable output voltage and the rated voltage controls the output current of the inverter to obtain the second stable output voltage, which can be obtained.
- the second stable output voltage which is closer to the rated voltage, is convenient to improve the efficiency of controlling the output voltage.
- the second correlation relationship is obtained according to the first stable output voltage, the first apparent power, the second stable output voltage and the second apparent power, which can improve the accuracy of obtaining the second correlation relationship.
- the fourth correlation relationship is adjusted according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage to obtain the third correlation relationship, which can improve the efficiency of controlling the output voltage.
- the inverter is further configured to calculate the minimum output voltage and the maximum output voltage of the inverter within the preset range of the rated voltage, and the maximum output voltage corresponding to the minimum output voltage.
- the first correlation relationship is obtained from the apparent power and the minimum apparent power corresponding to the maximum output voltage. It can be understood that the output voltage of the inverter has a negative correlation with the apparent power, so that the maximum apparent power corresponding to the minimum output voltage and the minimum output voltage of the inverter within the preset range of the rated voltage, and the maximum apparent power at the rated voltage can be obtained.
- the maximum output voltage within the preset voltage range and the minimum apparent power corresponding to the maximum output voltage obtain the first correlation relationship, which improves the accuracy of obtaining the first correlation relationship.
- the first association relationship includes a first formula:
- the PN is the rated power of the inverter
- the U L is the minimum output voltage
- the U H is the maximum output voltage
- the U i is the output of the inverter voltage
- the S 1 (U i ) is the apparent power of the inverter when the output voltage of the inverter is U i .
- the fourth correlation relationship is used to indicate that when the first stable output voltage is less than the rated voltage, in the fourth correlation relationship, the inverter is within the rated voltage
- the maximum apparent power corresponding to the preset range is greater than the maximum apparent power corresponding to the inverter within the preset range of the rated voltage in the first correlation relationship; when the first stable output voltage is greater than or When it is equal to the rated voltage, the maximum apparent power corresponding to the inverter within the preset range of the rated voltage in the fourth relationship is smaller than that of the inverter in the first relationship.
- the maximum apparent power corresponding to the preset range of the rated voltage is used to indicate that when the first stable output voltage is less than the rated voltage, in the fourth correlation relationship, the inverter is within the rated voltage
- the maximum apparent power corresponding to the preset range is greater than the maximum apparent power corresponding to the inverter within the preset range of the rated voltage in the first correlation relationship; when the first stable output voltage is greater than or When it is equal to the
- the fourth association relationship includes the second formula:
- the PN is the rated power of the inverter
- the U L is the minimum output voltage of the inverter within the preset range of the rated voltage
- the U H is the inverter is the maximum output voltage of the inverter within the preset range of the rated voltage
- the U i is the output voltage of the inverter
- the S 1 * (U i ) is the output voltage of the inverter U
- the U 1 is the first stable output voltage
- the U N is the rated voltage
- the k 1 is the first stable output voltage less than the The correlation coefficient when the rated voltage is used
- the k 2 is the correlation coefficient when the first stable output voltage is greater than or equal to the rated voltage.
- the second association relationship includes a third formula:
- the U i is the output voltage of the inverter
- the U 1 is the first stable output voltage
- the U 2 is the second stable output voltage
- the S 1 (U 1 ) is the first apparent power
- the S 1 * (U 2 ) is the second apparent power
- S 1 (U i ) is the inverter when the output voltage of the inverter is U i is the apparent power of the inverter
- S 2 (U i ) is the apparent power of the load when the output voltage of the inverter is U i .
- the inverter is specifically configured to determine the fourth correlation relationship according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage The value of the correlation coefficient; the fourth correlation relationship is updated according to the value of the correlation coefficient to obtain the first negative correlation between the output voltage of the inverter and the apparent power of the inverter.
- Three relationships It can be understood that updating the relational coefficient in the fourth relational relation through the magnitude relation between the second relational relation, the first stable output voltage and the rated voltage can improve the accuracy of obtaining the third relational relation and facilitate the control of the output voltage. s efficiency.
- the formula for calculating the value k of the relationship coefficient includes the fourth formula:
- the PN is the rated power of the inverter
- the U L is the minimum output voltage of the inverter within the preset range of the rated voltage
- the U H is the inverter is the maximum output voltage of the inverter within the preset range of the rated voltage
- the U 1 is the first stable output voltage
- S 2 (U i ) is the output voltage of the inverter when the output voltage is U N Apparent power of the load.
- the inverter is specifically configured to obtain the target apparent power corresponding to the rated voltage according to the third association relationship; and the output to the inverter according to the target apparent power The current is controlled so that the output voltage of the inverter satisfies the preset range of the rated voltage.
- the third correlation relationship is used to describe the correlation relationship between the output voltage of the inverter and the apparent power, and the target apparent power corresponding to the rated voltage can be obtained according to the third correlation relationship.
- the apparent power is related to the output voltage and output current
- the current output current of the inverter can be tracked according to the target apparent power, and the drive signal corresponding to the rated voltage can be obtained, and then the inverter can be controlled to operate based on the drive signal. Therefore, by controlling the output voltage of the inverter, the output voltage of the inverter can meet the preset range of the rated voltage, and the control efficiency and the stability of the inverter operation are improved, thereby improving the stability of the load operation.
- the inverter is specifically configured to determine whether the energy storage system is in an island state according to the output voltage of the inverter in response to the operating mode being the current source mode. In this way, whether the energy storage system is in the island state is determined by the output voltage of the inverter, which can improve the efficiency and accuracy of determining the island state.
- an embodiment of the present application discloses a method for switching between on-grid and off-grid modes, which is applied to an energy storage system.
- the energy storage system includes a controller, an inverter, a switch in on-grid and off-grid modes, and a load, wherein:
- the inverter In response to determining that the energy storage system is in an island state, the inverter sends an island state message to the controller, and freezes the output frequency of the inverter according to a preset frequency, and according to the inverter There is a negative correlation between the output voltage of the inverter and the apparent power of the inverter, and the output current of the inverter is controlled so that the output voltage of the inverter satisfies the preset rated voltage. scope;
- the controller sends a disconnection instruction to the on-grid mode switch, where the disconnection instruction is used to instruct the on-grid and off-grid mode switch to disconnect from the power grid;
- the controller In response to receiving a disconnection completion message from the on-grid mode switch, the controller sends a switching instruction to the inverter, and the disconnection completion message is used to instruct the on-grid and off-grid mode switch to communicate with the inverter.
- the grid disconnection has been completed, and the switching instruction is used to instruct the inverter to switch to the voltage source mode;
- the inverter switches to the voltage source mode in response to receiving the switching instruction and determining that the output voltage of the inverter meets a preset range of the rated voltage.
- the output frequency of the inverter is frozen according to the preset frequency, so as to avoid the occurrence of frequency distortion.
- the occurrence of voltage distortion events can be avoided, and the control efficiency of the inverter is improved compared with the direct control of the output voltage.
- the output current of the inverter is controlled according to the negative correlation relationship between the output voltage of the inverter and the apparent power of the inverter, include:
- the inverter controls the output current of the inverter according to the first correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated to obtain the The first stable output voltage of the inverter and the first apparent power corresponding to the first stable output voltage, and the variation range of the first stable output voltage is less than or equal to the preset range.
- the method further includes:
- the second correlation relationship that is positively correlated between the output voltage of the inverter and the apparent power of the load, and the magnitude relationship between the first stable output voltage and the rated voltage Adjusting the first correlation relationship to obtain a third correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated;
- the inverter controls the output current of the inverter according to the third correlation relationship and the rated voltage, so that the output voltage of the inverter meets a preset range of the rated voltage.
- the first correlation between the output voltage of the inverter and the apparent power of the inverter is adjusted to obtain The third correlation relationship, so that the output current of the inverter is controlled according to the third correlation relationship and the rated voltage, the efficiency and accuracy of the control can be improved, and the stability of the load operation can be further improved.
- the second correlation according to the positive correlation between the output voltage of the inverter and the apparent power of the load, the relationship between the first stable output voltage and the rated voltage
- the magnitude relationship adjusts the first correlation relationship to obtain a third correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated, including:
- the inverter adjusts the first correlation relationship according to the magnitude relationship between the first stable output voltage and the rated voltage to obtain the output voltage of the inverter and the apparent power of the inverter
- the fourth relationship is negatively correlated
- the inverter controls the output current of the inverter according to the fourth correlation relationship, so as to obtain a second stable output voltage of the inverter and a second apparent voltage corresponding to the second stable output voltage. power, the variation range of the second stable output voltage is less than or equal to the preset range.
- the fourth correlation relationship obtained by adjusting the first correlation relationship through the magnitude relationship between the first stable output voltage and the rated voltage controls the output current of the inverter to obtain the second stable output voltage, which can be obtained.
- the second stable output voltage which is closer to the rated voltage, is convenient to improve the efficiency of controlling the output voltage.
- the method further includes:
- the inverter obtains the output voltage of the inverter and the load according to the first stable output voltage, the first apparent power, the second stable output voltage and the second apparent power
- the second correlation relationship that is positively correlated between the apparent powers
- the inverter adjusts the fourth correlation relationship according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage to obtain the output voltage of the inverter and
- the apparent powers of the inverters have a third correlation relationship in which they are negatively correlated.
- the fourth correlation relationship is adjusted according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage to obtain the third correlation relationship, which can improve the efficiency of controlling the output voltage.
- the method further includes:
- the inverter is based on the minimum output voltage and the maximum output voltage of the inverter within the preset range of the rated voltage, and the maximum apparent power corresponding to the minimum output voltage and the maximum output voltage.
- the minimum apparent power obtains the first association relationship.
- the output voltage of the inverter has a negative correlation with the apparent power, so that the maximum apparent power corresponding to the minimum output voltage and the minimum output voltage of the inverter within the preset range of the rated voltage, and the maximum apparent power at the rated voltage can be obtained.
- the maximum output voltage within the preset voltage range and the minimum apparent power corresponding to the maximum output voltage obtain the first correlation relationship, which improves the accuracy of obtaining the first correlation relationship.
- the first association relationship includes a first formula:
- the PN is the rated power of the inverter
- the U L is the minimum output voltage
- the U H is the maximum output voltage
- the U i is the output of the inverter voltage
- the S 1 (U i ) is the apparent power of the inverter when the output voltage of the inverter is U i .
- the fourth correlation relationship is used to indicate that when the first stable output voltage is less than the rated voltage, in the fourth correlation relationship, the inverter is within the rated voltage
- the maximum apparent power corresponding to the preset range is greater than the maximum apparent power corresponding to the inverter within the preset range of the rated voltage in the first correlation relationship; when the first stable output voltage is greater than or When it is equal to the rated voltage, the maximum apparent power corresponding to the inverter within the preset range of the rated voltage in the fourth relationship is smaller than that of the inverter in the first relationship.
- the maximum apparent power corresponding to the preset range of the rated voltage is used to indicate that when the first stable output voltage is less than the rated voltage, in the fourth correlation relationship, the inverter is within the rated voltage
- the maximum apparent power corresponding to the preset range is greater than the maximum apparent power corresponding to the inverter within the preset range of the rated voltage in the first correlation relationship; when the first stable output voltage is greater than or When it is equal to the
- the fourth association relationship includes the second formula:
- the PN is the rated power of the inverter
- the U L is the minimum output voltage of the inverter within the preset range of the rated voltage
- the U H is the inverter is the maximum output voltage of the inverter within the preset range of the rated voltage
- the U i is the output voltage of the inverter
- the S 1 * (U i ) is the output voltage of the inverter U
- the U 1 is the first stable output voltage
- the U N is the rated voltage
- the k 1 is the first stable output voltage less than the The correlation coefficient when the rated voltage is used
- the k 2 is the correlation coefficient when the first stable output voltage is greater than or equal to the rated voltage.
- the second association relationship includes a third formula:
- the U i is the output voltage of the inverter
- the U 1 is the first stable output voltage
- the U 2 is the second stable output voltage
- the S 1 (U 1 ) is the first apparent power
- the S 1 * (U 2 ) is the second apparent power
- S 1 (U i ) is the inverter when the output voltage of the inverter is U i is the apparent power of the inverter
- S 2 (U i ) is the apparent power of the load when the output voltage of the inverter is U i .
- the fourth correlation relationship is adjusted according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage to obtain the inverter
- the third correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated including:
- the inverter determines the value of the correlation coefficient in the fourth correlation relationship according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage;
- the inverter updates the fourth association relationship according to the value of the association coefficient to obtain the third association relationship.
- the formula for calculating the value k of the relationship coefficient includes the fourth formula:
- the PN is the rated power of the inverter
- the U L is the minimum output voltage of the inverter within the preset range of the rated voltage
- the U H is the inverter is the maximum output voltage of the inverter within the preset range of the rated voltage
- the U 1 is the first stable output voltage
- S 2 (U i ) is the output voltage of the inverter when the output voltage is U N Apparent power of the load.
- controlling the output current of the inverter according to the third correlation relationship and the rated voltage includes:
- the inverter controls the output current of the inverter according to the target apparent power.
- the third correlation relationship is used to describe the correlation relationship between the output voltage of the inverter and the apparent power, and the target apparent power corresponding to the rated voltage can be obtained according to the third correlation relationship.
- the apparent power is related to the output voltage and output current
- the current output current of the inverter can be tracked according to the target apparent power, and the drive signal corresponding to the rated voltage can be obtained, and then the inverter can be controlled to operate based on the drive signal. Therefore, by controlling the output voltage of the inverter, the output voltage of the inverter can meet the preset range of the rated voltage, and the control efficiency and the stability of the inverter operation are improved, thereby improving the stability of the load operation.
- the method further includes: in response to the operating mode of the inverter being a current source mode, determining whether the energy storage system is in an island state according to an output voltage of the inverter. In this way, whether the energy storage system is in the island state is determined by the output voltage of the inverter, which can improve the efficiency and accuracy of determining the island state.
- the preset frequency includes a rated frequency of the load, or an output frequency of the inverter when the energy storage system is in an island state.
- the rated frequency of the load is the frequency suitable for the load to work, and the rated frequency of the load is used as the preset frequency, and the output frequency of the inverter is frozen, so that the output frequency of the inverter is the rated frequency of the load.
- the stability of the load to work The output frequency of the inverter when the energy storage system is in the island state is used as the preset frequency, and the output frequency of the inverter is frozen according to the preset frequency, so that the output frequency of the inverter is the reverse when the energy storage system is in the island state.
- the output frequency of the inverter can be adjusted so that the input frequency of the load does not change in a short period of time, which can improve the stability of the load operation.
- FIG. 1 is a schematic structural diagram of an energy storage system provided by an embodiment of the present application.
- FIG. 2 is a schematic structural diagram of an inverter provided by an embodiment of the present application.
- FIG. 3 is a schematic structural diagram of another energy storage system provided by an embodiment of the present application.
- FIG. 5 is a characteristic curve diagram between a wasteful power and an output voltage provided by an embodiment of the present application.
- FIG. 9 is a schematic flowchart of a method for switching between on-grid and off-grid modes provided by an embodiment of the present application.
- FIG. 10 is a schematic flowchart of another method for switching between on-grid and off-grid modes provided by an embodiment of the present application.
- the present application provides an energy storage system, which integrates the functions of charging, storing electricity and discharging.
- the type of energy storage it can include systems such as wind power generation systems and photovoltaic power generation systems, and can be applied to large-scale, small and medium-sized distributed, micro-grid or user-side scenarios according to the type of scenarios, which is not limited here.
- the power grid involved in this application is also called the power grid, including substations and transmission and distribution lines of various voltages in the power system, that is, three units of substation, transmission, and distribution, which are used to transmit and distribute electric energy, change voltage, etc. , which is not limited here.
- the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.
- the energy storage system 100 may include a controller 101 , an on/off grid mode switch 102 , an inverter 103 , an energy storage subsystem 104 , a power grid 105 , a load 106 , etc., which are not limited herein.
- the energy storage subsystem 104 can be connected to at least one inverter 103 directly or by DC coupling
- the inverter 103 and the on-off-grid mode switch 102 can be connected to the controller 101
- the controller 101 can also be connected to the grid 105
- the grid 105 may connect at least one load 106 .
- the energy storage subsystem 104 may be an energy storage system (Energy Storage System, ESS), which may include a battery module, a DC/DC converter, and the like.
- ESS Energy Storage System
- the ESS may also include photovoltaic power generation modules, etc., which are not limited here.
- the above-mentioned battery modules and photovoltaic power generation modules can both be used to provide the DC voltage on the power generation side of the energy storage system 100 .
- a DC/DC converter can be used to convert the DC voltage on the power generation side into a voltage form required by the inverter 103 .
- the inverter 103 may include an energy storage inverter (Power Conditioning System, PCS), and the PCS may also be referred to as an energy storage converter, an energy conversion system, an energy converter, a grid-connected inverter, or a power inverter, etc. This is not limited.
- the inverter 103 is a converter that converts the received DC voltage (eg, electric charges transmitted by batteries, storage batteries, photovoltaic modules, etc.) into constant-frequency constant-voltage or frequency-modulated and voltage-regulated AC power, and is used for the power grid 105 or the power grid.
- the load 106 to which 105 is connected supplies power.
- the inverter 103 In the grid-connected mode, the inverter 103 operates in the current source mode, the internal impedance characteristic is high impedance, and the frequency and phase of the grid voltage are actively detected to control the output current. In the off-grid mode, the internal impedance characteristic is low impedance, and the inverter 103 operates in the voltage source mode, actively determines the frequency, amplitude and phase information of the output voltage, and controls the output voltage.
- FIG. 2 is a schematic structural diagram of an inverter according to an embodiment of the present application. That is, the inverter 103 in FIG. 1 can be implemented by the structure in FIG. 2 .
- the inverter 103 may include an inverter circuit 107, a sampling circuit 108, a control circuit 109, a storage circuit 110, and the like.
- the inverter circuit 107 , the sampling circuit 108 , the control circuit 109 and the storage circuit 110 may be connected through a communication bus.
- the communication bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. limited.
- the communication bus can be divided into an address bus, a data bus, a control bus, etc., for example, a 485 bus.
- the functions of the inverter circuit 107, the sampling circuit 108, the control circuit 109 and the storage circuit 110 can be implemented by integrated circuits, for example, the inverter circuit 107, the sampling circuit 108, the control circuit 109 and the storage circuit 110 are integrated on a printed circuit board (Printed Circuit Board, PCB).
- PCB also known as printed circuit board, is an important electronic component, a support for electronic components, and a carrier for electrical connection of electronic components.
- the inverter circuit 107 is used to realize the main function of the inverter 103 , that is, to convert the DC voltage into a constant-frequency constant-voltage or a frequency-modulated and voltage-regulated AC power.
- the sampling circuit 108 is electrically connected to the inverter circuit 107 for detecting the output voltage and output current of each inverter circuit 107 , or the output voltage and output current of the entire inverter 103 .
- the sampling circuit 108 may include a sensor, for example, a current sensor and the like.
- the control circuit 109 may be electrically connected to the storage circuit 110 .
- the control circuit 109 refers to a component that can coordinate the work of each component according to the functional requirements of the instruction, and is the nerve center and command center of the inverter 103. It is composed of three components and an operation controller (OC), which is extremely important for coordinating the orderly work of the entire system.
- Control circuitry 109 herein may refer to one or more devices, circuits, and/or processing cores for processing data (eg, computer program instructions).
- control circuit 109 may be a processor, or may be a collective term for multiple processing elements.
- the processor may be a general-purpose central processing unit (Central Processing Unit, CPU), or may be an application-specific integrated circuit (application-specific Integrated Circuit, ASIC), or one or more processors for controlling the execution of the programs of the present application.
- Integrated circuit for example, one or more microprocessors (Digital Signal Processor, DSP), or, one or more Field Programmable Gate Array (Field Programmable Gate Array, FPGA).
- DSP Digital Signal Processor
- FPGA Field Programmable Gate Array
- the processor may include one or more CPUs.
- the storage circuit 110 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of static storage device that can store information and instructions.
- ROM read-only memory
- RAM random access memory
- Type of dynamic storage device it can also be Electrically Erasable Programmable Read-Only Memory (EEPROM), Compact Disc Read-Only Memory (CD-ROM) or other optical disk storage, CD-ROM storage (including compact discs, laser discs, compact discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or capable of carrying or storing desired program code in the form of instructions or data structures and capable of being accessed by Any other medium accessed by the computer, but not limited to this.
- EEPROM Electrically Erasable Programmable Read-Only Memory
- CD-ROM Compact Disc Read-Only Memory
- CD-ROM compact disc Read-Only Memory
- CD-ROM storage including compact discs, laser discs, compact
- the storage circuit 110 may be used to store data such as current, voltage, and power of the inverter circuit 107 .
- the storage circuit 110 is further used to store the application program code for executing the solution of the present application, and the control circuit 109 controls the execution. That is, the control circuit 109 is used to execute the application program code stored in the storage circuit 110 .
- the inverter 103 may include an inverter circuit 107 , a sampling circuit 108 , an islanding judgment unit 111 , a frequency freezing unit 112 , a voltage-frequency-power calculating unit 113 , and an apparent power-voltage amplitude model building unit 114, a load characteristic calculation unit 115, a parameter adaptation unit 116, a drive unit 117, a mode switching unit 118, and the like.
- the switching units 118 can be connected through a communication bus, and the functions of the above units can be implemented by an integrated circuit, which can be used as the control circuit 109 in FIG. 2 after integration.
- the island determination unit 111 may be used to determine whether the energy storage system 100 is in an island state.
- the frequency freezing unit 112 can be used to freeze the output frequency of the inverter 103 .
- the voltage-frequency-power calculation unit 113 may be used to calculate the output voltage, output current and output frequency of the inverter 103 .
- the apparent power-voltage magnitude model building unit 114 may be used to build a correlation model between the output voltage of the inverter 103 and the apparent power, for example, the difference between the output voltage of the inverter 103 and the apparent power of the inverter 103. relationship between.
- the load characteristic calculation unit 115 can be used to calculate the full load characteristic of the load 106 , for example, the relationship between the output voltage of the inverter 103 and the apparent power of the load 106 .
- the adaptation unit 116 may be used to adjust the correlation parameters in the correlation model constructed by the apparent power-voltage amplitude model construction unit 114 .
- the driving unit 117 can be used to obtain a drive signal, so that the drive signal controls the output current of the inverter 103, so as to obtain the output voltage corresponding to the output current after the control.
- the mode switching unit 118 can be used to switch the current source mode and the voltage source mode.
- the controller 101 may be a control circuit for controlling on/off-grid mode switching, such as a power plant controller (Power Plant Controller, PPC), etc., or may be other controllers, such as a system controller (System Control Unit, SCU), etc., which are not limited here.
- a power plant controller Power Plant Controller, PPC
- PPC Power Plant Controller
- SCU System Control Unit
- the on-grid mode switch 102 is used to connect to the grid 105 in the grid-connected mode and disconnect from the grid 105 in the off-grid mode. That is, the energy storage subsystem 104 is used to power the load 106 after the on-off-grid mode switch 102 is disconnected from the grid 105 . After the on-grid mode switch 102 is connected to the grid 105, the grid 105 supplies power to the load 106. It should be noted that the grid 105 and the energy storage subsystem 104 can supply power to the loads in the grid 105 at the same time.
- This application does not limit the switch state of the on-grid mode switch 102, which can be connected to the power grid 105 when turned on and disconnected from the power grid 105 when turned off; or disconnected from the power grid 105 when turned on, and connected to the power grid 105 when turned off.
- Grid 105 is connected.
- the load 106 involved in this application may be an electric appliance such as an air conditioner, a mobile phone, a computer, an electric water heater, an electric kettle, and an electric vehicle, and the type of the load 106 is not limited in this application. And the number of the loads 106 is not limited. In FIG. 1 , one load is used as an example for illustration.
- the active power has a parabolic relationship with the voltage amplitude. As shown in Equation 1 and FIG. 4 , when the line segments corresponding to points N1 and N2 indicate that the output voltage satisfies a small variation range of the rated voltage U N , the parabola is approximately a straight line.
- U rlc is the output voltage of the load
- R rlc is the resistance of the load
- P rlc (U rlc ) is the active power of the load
- the active power of the load changes with the output voltage of the load.
- reactive power has a two-dimensional nonlinear relationship with voltage amplitude and frequency. As shown in Equation 2, reactive power, voltage amplitude, and frequency are a three-dimensional relationship.
- U rlc is the output voltage of the load
- fr rlc is the frequency of the load
- C rlc is the capacitance of the load
- L rlc is the inductance of the load
- Q rlc (U rlc , fr rlc ) is the reactive power of the load
- the working power changes with the output voltage and frequency of the load.
- the structures illustrated in the embodiments of the present application do not constitute a specific limitation on the energy storage system 100 .
- the energy storage system 100 may include more or less components than shown, or combine some components, or separate some components, or different component arrangements.
- the illustrated components may be implemented in hardware, software, or a combination of software and hardware.
- the energy storage system 100 may further include a transformer not shown in FIG. 1 , the secondary side of the transformer may be connected to the inverter 103 independently or by AC coupling, and the primary side of the transformer may be connected to the on-grid mode switch 102 .
- the transformer may include a DC/DC converter that may be used to convert the AC voltage output by the inverter 103 into a voltage form required by the load 106 .
- the DC/DC circuit 10 may be configured with a circuit according to a specific application environment, for example, a buck circuit, a boost circuit, or a buck-boost circuit and the like.
- the inverter 103 is used to determine whether the energy storage system 100 is in an island state.
- the island state refers to a state in which the energy storage system 100 supplies power to the load 106 alone, that is, the power grid does not supply power to the load 106 .
- the present application does not limit the method for determining that the energy storage system 100 is in the island state.
- the inverter 103 is specifically configured to determine the energy storage system according to the output voltage of the inverter in response to the working mode being the current source mode. Whether the energy system is in an island state.
- the operating mode of the inverter 103 when the operating mode of the inverter 103 is the current source mode, it means that the energy storage system 100 is in the grid-connected mode.
- the inverter 103 can acquire the output voltage and output current of the inverter 103 in real time.
- the output voltage of the inverter 103 is an AC voltage
- the output current of the inverter 103 is an AC current. Since the inverter 103 is used as the output terminal of the energy storage system 100 to supply power to the load 106, the output voltage and output current of the inverter 103 can also be referred to as the voltage and current on the grid-connected side of the inverter 103.
- the inverter 103 may include at least one of the harmonic impedance method, the reactive power scrambling method, and the voltage-frequency distortion method, and determine whether the energy storage system 100 is not based on the output voltage of the inverter 103 . in an island state.
- the harmonic impedance method is based on two different working conditions: grid-connected mode and off-grid mode.
- the grid impedance detected by the inverter 103 will change, so that the harmonic impedance can be detected to assist in determining whether the grid jumps. , that is, whether the energy storage system 100 is in an island state is determined by detecting the harmonic impedance. Specifically, it can detect the change of even-order harmonics in the output voltage of the inverter 103.
- the harmonics output by the AC port of the inverter 103 will flow into the grid.
- the internal impedance of the grid is very small, so the total harmonic distortion rate of the AC port of the inverter 103 is usually relatively low.
- the inverter 103 is still working based on the grid-connected mode, that is, the energy storage system 100 is still in the grid-connected mode. If a grid jump event occurs, since the impedance of the local load is usually much larger than the impedance of the grid, the AC port of the inverter 103 will generate large harmonics, resulting in the occurrence of harmonics at the AC port of the inverter 103 mutation. Therefore, when the variation of the even harmonics in the output voltage of the inverter 103 is too large, it is determined that the inverter 103 may be disconnected from the grid, and it is determined that the energy storage system 100 is in an island state.
- the reactive power winding method is a more traditional anti-islanding protection method.
- the reactive power winding method is based on the fact that the greater the reactive power in the island state, the greater the frequency offset. Therefore, the frequency offset of the inverter 103 can be determined according to the output voltage of the inverter 103 by injecting reactive power into the energy storage system 100 . When it is determined that the frequency offset of the inverter 103 is too large, it is determined that the energy storage system 100 is in an island state.
- the voltage-frequency distortion method is based on determining that an abnormal event occurs in the power grid when the amplitude, frequency, and phase of the output voltage of the inverter 103 have a large sudden change, thereby determining that the energy storage system 100 is in an island state.
- harmonic impedance method and the voltage-frequency distortion method may lead to misjudgments, while using the reactive power winding method takes a long time, and voltage distortion, frequency distortion or The sudden change of phase affects the power supply to the load.
- the above harmonic impedance method, voltage frequency distortion method and reactive power winding method do not constitute limitations on the embodiments of the present application. In practical applications, other methods or a combination of the above methods may be used. Determine that the energy storage system is in an islanded state. It can be understood that using at least two of the above harmonic impedance method, voltage frequency distortion method and reactive power winding method to determine whether the energy storage system is in an islanding state can improve the accuracy of islanding judgment.
- the inverter 103 is further configured to send an island state message to the controller 101 in response to determining that the energy storage system 100 is in an island state, so that the controller 101 sends a disconnection command to the on-grid mode switch 102 , and send a switching instruction to the inverter 103 .
- the island state message is used to instruct the inverter 103 to determine that the energy storage system 100 is in the island state, and may include indication information indicating that the energy storage system 100 is in the island state, and may also include parameters for determining that the energy storage system 100 is in the island state, etc. limited.
- the disconnection command is used to instruct the on-grid mode switch 102 to disconnect from the grid 105, and the switch command is used to instruct the inverter 103 to switch to the voltage source mode.
- the current energy storage system 100 can enter the off-grid mode, and the off-grid mode switch 102 needs to be notified to disconnect from the power grid 105, and the inverter 103 needs to be notified from the current source.
- the mode is switched to voltage source mode.
- the on-grid and off-grid mode switch 102 has a mechanical delay, and after the on-grid and off-grid mode switch 102 is turned off There is a transmission delay in sending the disconnection completion message to the controller 101 , which leads to a long process of switching between on-grid and off-grid modes, and voltage distortion or frequency distortion may occur during the switching process, which affects the power supply to the load 106 .
- the inverter 103 is further configured to freeze the output frequency of the inverter 103 according to the preset frequency in response to the energy storage system 100 being in the island state, and according to the output voltage of the inverter 103 According to the relationship proportional to the apparent power of the inverter 103, the output current of the inverter 103 is controlled so that the output voltage of the inverter 103 satisfies the preset range of the rated voltage.
- the preset frequency may be the rated frequency of the load 106 .
- the rated frequency of the load 106 is a frequency set for the load 106 in advance, and may be 50 Hz or the like. It can be understood that the rated frequency of the load 106 is a frequency suitable for the operation of the load 106, and the rated frequency of the load 106 is used as the preset frequency, and the output frequency of the inverter 103 is frozen, so that the output frequency of the inverter 103 is the load
- the rated frequency of 106 improves the stability of the load 106 to work.
- the preset frequency may also be the frequency of the inverter 103 when the energy storage system 100 is in an island state, etc., which is not limited herein.
- the frequency of the inverter 103 when the energy storage system 100 is in the island state is taken as The preset frequency is to freeze the output frequency of the inverter 103 according to the preset frequency, so that the output frequency of the inverter 103 is the frequency of the inverter 103 when the energy storage system 100 is in the island state, so that the input frequency of the load 106 There is no change in a short time, and the stability of the load 106 can be improved.
- This application does not limit the rated voltage, which can be 220V or others.
- the present application does not limit the preset range, which may be ⁇ 10% or the like.
- the correlation relationship may be represented by a correlation function between the output voltage of the inverter 103 and the apparent power of the inverter 103 .
- frlc in Equation 2 can be regarded as a fixed value, and the fixed value is the preset frequency.
- the reactive power has a parabolic relationship with the voltage amplitude of the output voltage, and when the line segments corresponding to points N3 and N4 are the smaller variation range of the output voltage satisfying the rated voltage U N , the parabola approximates for a straight line.
- U rlc is the output voltage of the load
- fr rlc is the frequency of the load
- C rlc is the capacitance of the load
- L rlc is the inductance of the load
- Q rlc (U rlc ) is the reactive power of the load
- the reactive power of the load follows the The output voltage of the load varies.
- the load characteristic is the voltage amplitude of the power and the output voltage.
- the full load characteristics of the load are shown in Equation 4 and Figure 6.
- the apparent power and the voltage amplitude of the output voltage have a parabolic relationship, and the line segment corresponding to the point N5 and the point N6 is the smaller one where the output voltage meets the rated voltage U N.
- the parabola approximates a straight line.
- U rlc is the output voltage of the load
- P rlc (U rlc ) is the active power of the load
- Q rlc (U rlc ) is the reactive power of the load
- S rlc (U rlc ) is the apparent power of the load.
- the output voltage of the inverter 103 and the apparent voltage of the inverter 103 can be obtained.
- the line segment L1 is used to describe the relationship between the output voltage of the inverter 103 and the apparent power of the inverter 103
- the line segment L2 is used to describe the output voltage of the inverter 103 and the apparent power of the load 106 .
- intersection point there is an intersection point between the line segment L1 and the line segment L2, and the intersection point can be regarded as the point where the energy storage system 100 operates stably under the action of the two correlations, and it can also be understood as a voltage where the output voltage of the inverter 103 will not be distorted, In other words, when the inverter 103 operates with the output voltage and apparent power corresponding to the intersection point, the occurrence of voltage distortion events can be avoided. It should be noted that the amplitude of the output voltage corresponding to the intersection is between the minimum output voltage UL and the maximum output voltage UH of the inverter 103 within the preset range of the rated voltage.
- the above-mentioned U L and U H can also be regarded as the maximum output voltage and the minimum output voltage of the load 106 within the preset range of the rated voltage.
- the present application does not limit the sizes of UL and UH .
- the range between UL and UH is relatively small.
- the load 106 is sensitive to changes in voltage
- the rated voltage is 800Vac
- the rated voltage is 800Vac
- the output frequency of the inverter 103 can also be frozen according to the preset frequency, so as to avoid the occurrence of frequency distortion events, and according to the preset range of the rated voltage , there is a negative correlation between the output voltage of the inverter 103 and the apparent power of the inverter 103 , and the output current of the inverter 103 can be controlled to make the inverter 103 run stably and the output voltage Stable to meet the preset range of rated voltage. In this way, the occurrence of voltage distortion events can be avoided, and the output voltage can be controlled by controlling the output current. Compared with directly controlling the output voltage, the control efficiency of the inverter 103 is improved, and the operation stability of the load 106 is improved. .
- the present application does not limit the method for obtaining the correlation between the output voltage of the inverter 103 and the apparent power of the inverter 103 .
- the range of apparent power of the inverter 103 is mapped to the operating range of the output voltage, that is to say, the maximum output voltage U H of the inverter 103 corresponds to the minimum apparent power of the inverter 103 , and the The minimum output voltage UL corresponds to the maximum apparent power corresponding to the inverter 103 .
- the inverter 103 is further configured to:
- the maximum apparent power and the minimum apparent power corresponding to the maximum output voltage U H obtain the first correlation relationship in which the output voltage of the inverter 103 and the apparent power of the inverter 103 are negatively correlated.
- the maximum apparent power corresponding to the minimum output voltage UL and the minimum output voltage UL of the inverter 103 within the preset range of the rated voltage, and the maximum output of the inverter 103 within the preset range of the rated voltage obtains a first correlation relationship (for example, a binary solution is performed according to the minimum output voltage U L , the maximum apparent power, the maximum output voltage U H and the minimum apparent power. equation to obtain the linear equation corresponding to the first correlation relationship), which improves the accuracy of obtaining the first correlation relationship.
- the maximum apparent power may be the rated power P N of the inverter 103 , and the minimum apparent power may be 0.
- the linear equation corresponding to the first correlation relationship includes the first formula, and the first formula is shown in formula (5):
- the inverter 103 is specifically configured to control the output current of the inverter according to the first correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated , obtain the first stable output voltage of the inverter and the first apparent power corresponding to the first stable output voltage, and the variation range of the first stable output voltage is less than or equal to the preset range;
- the second correlation relationship in which the apparent power is positively correlated, the magnitude relationship between the first stable output voltage and the rated voltage is adjusted to adjust the first correlation relationship to obtain the difference between the output voltage of the inverter and the apparent power of the inverter.
- the third correlation relationship is negatively correlated; the output current of the inverter is controlled according to the third correlation relationship and the rated voltage, so that the output voltage of the inverter meets the preset range of the rated voltage.
- the variation range of the first stable output voltage is less than or equal to the preset range, that is, when the output voltage of the inverter 103 is between the minimum output voltage U L and the maximum output voltage U H , and the When the variation range of the output voltage is less than or equal to the preset range, the corresponding output voltage is , and it can be determined that the output voltage is the first stable output voltage.
- the first correlation relationship in which the output voltage of the inverter 103 and the apparent power of the inverter 103 are negatively correlated can be determined according to the first correlation relationship, and The output current of the inverter 103 controls the output voltage of the inverter 103, so that the first stable output voltage and the first apparent power corresponding to the first stable output voltage can be obtained, so that frequency distortion and voltage distortion of the load 106 can be avoided. , which can ensure that the load 106 can run stably within a relatively short period of time.
- the above-mentioned first stable output voltage may not be equal to the rated voltage, and the first correlation relationship does not take into account the load characteristics of the load 106, and the output current of the inverter 103 is controlled based on the first correlation relationship, so it is difficult to obtain a voltage for continuous and stable operation. .
- the point of intersection between the correlation between the output voltage of the inverter 103 and the apparent power of the inverter 103 and the correlation between the output voltage of the inverter 103 and the apparent power of the load 106 is stable point, the first correlation can be optimized based on the correlation between the output voltage of the inverter 103 and the apparent power of the load 106 .
- the relationship between the output voltage of the inverter 103 and the apparent power of the load 106 is referred to as the second relationship, and the second relationship is used to describe when the inverter is adjusted according to the preset frequency.
- the full load characteristic of the load 106 after the output frequency of the converter 103 is frozen.
- the third correlation is the correlation obtained after the first correlation is adjusted, and is obtained by adjusting the second correlation between the output voltage of the inverter 103 and the apparent power of the load 106 . Since the second correlation is used to describe the full load characteristic after the output frequency of the inverter 103 is frozen according to the preset frequency, the third correlation can be improved to describe the relationship between the output voltage and the apparent power of the inverter 103 The accuracy of the association relationship.
- the accuracy and efficiency that the output voltage of the inverter 103 meets the preset range of the rated voltage can be improved, thereby improving the operating efficiency of the load 106 stability.
- the present application does not limit the method for obtaining the second association relationship.
- Two points at which the load 106 can run stably can be determined first, and then a straight line can be determined based on the two points, so as to obtain the output voltage of the inverter 103 and the output voltage of the inverter.
- the first stable operating voltage and the first apparent power are a point on the second relationship.
- the present application does not limit the method for obtaining another point on the second correlation relationship.
- the inverter 103 is further configured to perform a A correlation relationship is adjusted to obtain a fourth correlation relationship in which the output voltage of the inverter 103 and the apparent power of the inverter 103 are negatively correlated; according to the fourth correlation relationship and the output current of the inverter 103, the inverter The output voltage of the inverter 103 is controlled to obtain the second stable output voltage of the inverter 103 and the second apparent power corresponding to the second stable output voltage.
- the fourth correlation is the correlation obtained after the first correlation is adjusted, and the fourth correlation is also used to describe the negative correlation between the output voltage of the inverter 103 and the apparent power of the inverter 103 connection relation.
- the variation range of the second stable output voltage is less than or equal to the preset range. That is to say, the second stable output voltage is the stable output voltage obtained when the output voltage of the inverter 103 is controlled according to the second relationship, and the stable output voltage is between the minimum output voltage U L and the maximum output voltage U H , the variation range is less than or equal to the preset range.
- the present application does not limit the method for obtaining the fourth association relationship, and the slope and intercept of the line segment corresponding to the first association relationship can be adjusted.
- the fourth correlation relationship is used to indicate that when the first stable output voltage is less than the rated voltage, in the fourth correlation relationship.
- the maximum apparent power corresponding to the inverter 103 within the preset range of the rated voltage is greater than the maximum apparent power corresponding to the inverter 103 within the preset range of the rated voltage in the first relationship; when the first stable output voltage is greater than or equal to the rated voltage, the maximum apparent power corresponding to the inverter 103 within the preset range of the rated voltage in the fourth relationship is smaller than the maximum apparent power corresponding to the inverter 103 within the preset range of the rated voltage in the first relationship. inspecting power.
- the line segment L1 , the line segment L3 and the line segment L4 respectively describe the relationship between the output voltage of the inverter 103 and the apparent power of the inverter 103
- the line segment L2 describes the output voltage of the inverter 103 and the apparent power of the inverter 103
- the relationship between the apparent powers of the loads 106 (ie, the second relationship), and the line segment L1 may be the line segment corresponding to the first relationship relationship
- the line segment L3 and the line segment L4 may be respectively different line segments corresponding to the fourth relationship relationship.
- the line segment L1, the line segment L3 and the line segment L4 respectively have an intersection point with the line segment L2, and the intersection points are M1, M2 and M3 respectively.
- the intersection between the line segment corresponding to the output voltage of the inverter 103 and the apparent power of the inverter 103 and the line segment corresponding to the output voltage of the inverter 103 and the apparent power of the load 106 is the inverter 103
- the first correlation relationship needs to be adjusted to obtain the fourth correlation relationship.
- the line segment L1 can be adjusted to the line segment L4, so that the line segment L4 corresponding to the fourth relationship and the line segment L2 corresponding to the intersection point M3
- the output voltage is greater than the first stable output voltage
- the maximum apparent power corresponding to the intersection point M5 of the line segment L4 and the vertical axis is greater than the maximum apparent power corresponding to the intersection point M4 of the line segment L1 and the vertical axis
- the line segment L1 can be adjusted to the line segment L3, so that the output voltage corresponding to the intersection point M2 between the line segment L3 and the line segment L2 corresponding to the fourth relationship is smaller than the first stable output voltage, the line segment L3 and the intersection point M6 of the vertical axis
- the corresponding maximum apparent power is smaller than the maximum apparent power corresponding to the intersection point M4 of the line segment L1 and the vertical axis
- the fourth association relationship includes a second formula, and the second formula is shown in formula (6):
- PN is the rated power of the inverter 103
- U L is the minimum output voltage of the inverter 103
- U H is the maximum output voltage of the inverter 103 within the preset range of the rated voltage
- U i is the inverter is the output voltage of the inverter 103
- S 1 * (U i ) is the apparent power of the inverter 103 when the output voltage of the inverter 103 is U i
- U 1 is the first stable output voltage
- U N is the rated voltage
- k 1 is the correlation coefficient in the second formula when the first stable output voltage is less than the rated voltage
- k 2 is the correlation coefficient in the second formula when the first stable output voltage is greater than or equal to the rated voltage.
- the slope and intercept of the line segment corresponding to the first correlation relationship are adjusted based on the correlation coefficient k 1 , so that the line segment corresponding to the fourth correlation relationship can be
- the intersection point between the line segments corresponding to the second association relationship is located to the right of the intersection point between the line segment corresponding to the first association relationship and the line segment corresponding to the second association relationship, so that the second stable output voltage is greater than the first stable output voltage.
- the slope and intercept of the line segment corresponding to the first correlation relationship are adjusted based on the correlation coefficient k 2 , so that the line segment corresponding to the fourth correlation relationship can be
- the intersection point between the line segments corresponding to the association relationship is located to the left of the intersection point between the line segment corresponding to the first association relationship and the line segment corresponding to the second association relationship, so that the second stable output voltage is smaller than the first stable output voltage.
- the inverter 103 After acquiring the second point in the second correlation relationship (that is, the point corresponding to the second stable operating voltage and the second apparent power), in a possible example, the inverter 103 is further configured to The stable output voltage, the first apparent power, the second stable output voltage, and the second apparent power obtain a second correlation relationship in which there is a positive correlation between the output voltage of the inverter 103 and the apparent power of the load. In this way, the accuracy of acquiring the second association relationship is improved.
- the second association relationship includes a third formula
- the third formula is shown in formula (7):
- U i is the output voltage of the inverter
- U 1 is the first stable output voltage
- U 2 is the second stable output voltage
- S 1 (U 1 ) is the first apparent power
- S 1 * (U 2 ) is the second apparent power
- S 1 (U i ) is the apparent power of the inverter when the output voltage of the inverter is U i
- S 2 (U i ) is the load when the output voltage of the inverter is U i the apparent power.
- the inverter 103 is specifically configured to adjust the fourth correlation relationship according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage, A third correlation relationship in which the output voltage of the inverter 103 and the apparent power of the inverter 103 are negatively correlated is obtained. In this way, the accuracy of acquiring the third association relationship can be improved.
- the inverter 103 is specifically configured to determine the first correlation relationship according to the magnitude relationship between the second correlation relationship, the first stable output voltage and the rated voltage. The value of the correlation coefficient in the four correlation relationships; according to the value of the correlation coefficient, the fourth correlation relationship is updated to obtain the third correlation relationship.
- the correlation coefficient is used to adjust the slope and intercept of the correlation relationship as mentioned above, that is, after updating the correlation coefficient, the line segment corresponding to the fourth correlation relationship can be adjusted, so that the third correlation relationship and the second correlation relationship can be adjusted.
- the output voltage at the intersection of the corresponding line segments between the relationships is the rated voltage.
- the calculation formula for the value k of the correlation coefficient includes a fourth formula, and the fourth formula is shown in formula (8):
- PN is the rated power of the inverter
- U L is the minimum output voltage of the inverter
- U H is the maximum output voltage of the inverter
- U 1 is the first stable output voltage
- S 2 (U i ) is The output voltage of the inverter is the apparent power of the load when U N.
- the output voltage of the inverter 103 may be controlled based on the current output current and rated voltage of the inverter 103 so that the output voltage satisfies the preset range of the rated voltage.
- the present application does not limit the method for controlling the output voltage of the inverter 103 to meet the preset range of the rated voltage.
- the inverter 103 is specifically configured to obtain the target corresponding to the rated voltage according to the third association relationship Apparent power rate; according to the target apparent power and the output current of the inverter, the output voltage of the inverter is controlled.
- the third correlation relationship is used to describe the correlation relationship between the output voltage of the inverter 103 and the apparent power, and the target apparent power corresponding to the rated voltage can be obtained according to the third correlation relationship.
- the apparent power is related to the output voltage and output current, so the current output current of the inverter 103 can be tracked according to the target apparent power to obtain the drive signal corresponding to the rated voltage, and then the inverter 103 can be controlled based on the drive signal. Therefore, by controlling the output voltage of the inverter 103, the output voltage of the inverter 103 can meet the preset range of the rated voltage, the control efficiency and the stability of the inverter 103 operation are improved, and the load 106 is improved. Operational stability.
- the controller 101 is further configured to send a disconnection instruction to the on-grid mode switch 102; in response to receiving the disconnection completion message from the on-grid and off-grid mode switch 102, send a switch instruction to the inverter 103 .
- the disconnection instruction is used to instruct the on-grid mode switch 102 to disconnect from the power grid 105
- the disconnect completion message is used to indicate that the disconnection of the on-grid mode switch 102 from the power grid 105 has been completed
- the switch instruction is used to instruct the inverter
- the controller 103 switches to the voltage source mode. That is to say, after the on-grid mode switch 102 is disconnected from the grid, it sends a disconnection completion message to the controller 101 to indicate that the on-grid mode switch 102 has been disconnected from the grid, and then informs the inverter 103 to perform Mode switching to achieve and off-grid mode switching.
- the output frequency of the inverter 103 can be frozen by the inverter 103 before the mode switching of the inverter 103, and then the output frequency of the inverter 103 can be frozen by the inverter 103.
- the output current is controlled to realize the control of the output voltage, which can avoid the occurrence of frequency distortion and voltage distortion, and improve the stability of the operation of the load 106 .
- the inverter 103 is further configured to switch to the voltage source mode in response to receiving the switching instruction and determining that the output voltage of the inverter 103 meets the preset range of the rated voltage. That is, after the inverter 103 receives the disconnection completion message from the grid-connected and off-grid mode switch 102, and after it is determined that the inverter 103 operates stably, and the output voltage of the inverter 103 meets the preset range of the rated voltage After that, it is switched to the voltage source mode, which further improves the stability of the operation of the load 106 .
- FIG. 9 shows a method for switching between on-grid and off-grid modes provided by an embodiment of the present application.
- the method is applied to an energy storage system, and the energy storage system includes a controller, an inverter, and an on-grid and off-grid mode switch. , grid and load.
- the method includes but is not limited to the following steps S901-S908, wherein:
- the inverter determines whether the energy storage system is in an island state.
- step S901 if it is determined in step S901 that the energy storage system is in an island state, then steps S902 and S903 are executed. Otherwise, continue to step S901.
- step S901 includes: in response to the operating mode of the inverter being the current source mode, determining whether the energy storage system is in an island state according to the output voltage of the inverter. In this way, whether the energy storage system is in the island state is determined by the output voltage of the inverter, which can improve the efficiency and accuracy of determining the island state.
- S903 The inverter freezes the output frequency of the inverter according to the preset frequency.
- the inverter controls the output current of the inverter according to the negative correlation relationship between the output voltage of the inverter and the apparent power of the inverter, so that the output voltage of the inverter meets the rated voltage preset range.
- step S904 includes: the inverter controls the output current of the inverter according to a first correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated , to obtain the first stable output voltage of the inverter and the first apparent power corresponding to the first stable output voltage.
- the variation range of the first stable output voltage is less than or equal to the preset range.
- the method further includes: the inverter according to the second correlation relationship in which the output voltage of the inverter and the apparent power of the load are positively correlated, and the magnitude relationship between the first stable output voltage and the rated voltage Adjust the second correlation relationship to obtain a third correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated;
- the output current is controlled so that the inverter operates stably, and the output voltage of the inverter satisfies the preset range of the rated voltage.
- the output current of the inverter is controlled according to the first correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated to obtain the output current of the inverter.
- the method further includes: according to the minimum output voltage and the maximum output voltage of the inverter within the preset range of the rated voltage, and the corresponding minimum output voltage. The first correlation relationship is obtained from the maximum apparent power and the minimum apparent power corresponding to the maximum output voltage.
- the output voltage of the inverter has a negative correlation with the apparent power, so that the maximum apparent power corresponding to the minimum output voltage and the minimum output voltage of the inverter within the preset range of the rated voltage, and the maximum apparent power at the rated voltage can be obtained.
- the maximum output voltage within the preset voltage range and the minimum apparent power corresponding to the maximum output voltage obtain the first correlation relationship, which improves the accuracy of obtaining the first correlation relationship.
- the first association relationship includes the first formula:
- P N is the rated power of the inverter
- U L is the minimum output voltage of the inverter within the preset range of the rated voltage
- U H is the maximum output voltage of the inverter within the preset range of the rated voltage
- U i is the output voltage of the inverter
- S 1 (U i ) is the apparent power of the inverter when the output voltage of the inverter is U i .
- the second correlation relationship is carried out according to the second correlation relationship in which the output voltage of the inverter and the apparent power of the load are positively correlated, and the magnitude relationship between the first stable output voltage and the rated voltage. Adjusting to obtain a third correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated, including: performing the first correlation relationship according to the magnitude relationship between the first stable output voltage and the rated voltage Adjust to obtain a fourth correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated; control the output voltage of the inverter according to the fourth correlation relationship and the output current of the inverter, Obtain the second stable output voltage of the inverter and the second apparent power corresponding to the second stable output voltage; obtain the inverse according to the first stable output voltage, the first apparent power, the second stable output voltage and the second apparent power.
- the variation range of the second stable output voltage is less than or equal to the preset range.
- the load corresponding to the energy storage system can be considered to remain unchanged or change little, and there is a negative correlation between the output voltage of the inverter and the apparent power, and it is related to the inverter. There is a stable operation intersection between the positive correlation between the output voltage of the load and the apparent power of the load.
- the first correlation relationship is adjusted to obtain the fourth correlation relationship, and then according to the corresponding first correlation relationship and the fourth correlation relationship
- the line segment controls the output voltage of the inverter to obtain the first apparent power corresponding to the first stable output voltage and the first stable output voltage, and the second apparent power corresponding to the second stable output voltage and the second stable output voltage. power, so as to obtain two points on the line segment corresponding to the output voltage of the inverter and the apparent power of the load.
- the second correlation relationship between the output voltage of the inverter and the apparent power of the load can be obtained, and the obtained The accuracy of the second association relationship.
- the three correlation relationship can improve the accuracy of obtaining the third correlation relationship, and is convenient to improve the stability of the load operation.
- the fourth correlation relationship obtained by adjusting the first correlation relationship through the magnitude relationship between the first stable output voltage and the rated voltage controls the output current of the inverter to obtain the second stable output voltage, which can be obtained.
- the second stable output voltage which is closer to the rated voltage, is convenient to improve the efficiency of controlling the output voltage.
- the second correlation relationship is obtained according to the first stable output voltage, the first apparent power, the second stable output voltage and the second apparent power, which can improve the accuracy of obtaining the second correlation relationship.
- the fourth correlation relationship is adjusted according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage to obtain the third correlation relationship, which can improve the efficiency of controlling the output voltage.
- the fourth relationship is used to indicate that when the first stable output voltage is less than the rated voltage, the maximum apparent power corresponding to the inverter within the preset range of the rated voltage in the fourth relationship is greater than the first The maximum apparent power corresponding to the inverter within the preset range of the rated voltage in a relationship; when the first stable output voltage is greater than or equal to the rated voltage, the inverter in the fourth relationship is within the preset range of the rated voltage The corresponding maximum apparent power is smaller than the maximum apparent power corresponding to the inverter within the preset range of the rated voltage in the first correlation relationship. In this way, the second stable output voltage obtained by the control through the fourth correlation relationship is closer to the rated voltage than the first stable output voltage, which is convenient to improve the efficiency of controlling the output voltage.
- the fourth association relationship includes the second formula:
- P N is the rated power of the inverter
- U L is the minimum output voltage of the inverter within the preset range of the rated voltage
- U H is the maximum output voltage of the inverter within the preset range of the rated voltage
- U i is the output voltage of the inverter
- S 1 * (U i ) is the apparent power of the inverter when the output voltage of the inverter is U i
- U 1 is the first stable output voltage
- U N is the rated voltage
- k 1 is the correlation coefficient when the first stable output voltage is less than the rated voltage
- k 2 is the correlation coefficient when the first stable output voltage is greater than or equal to the rated voltage.
- the second association relationship includes a third formula:
- U i is the output voltage of the inverter
- U 1 is the first stable output voltage
- U 2 is the second stable output voltage
- S 1 (U 1 ) is the first apparent power
- S 1 * (U 2 ) is the second apparent power
- S 1 (U i ) is the apparent power of the inverter when the output voltage of the inverter is U i
- S 2 (U i ) is the load when the output voltage of the inverter is U i the apparent power.
- the fourth correlation relationship is adjusted according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage to obtain the output voltage of the inverter and the apparent power of the inverter
- the third correlation relationship that is negatively correlated between them includes: determining the value of the correlation coefficient in the fourth correlation relationship according to the second correlation relationship, the magnitude relationship between the first stable output voltage and the rated voltage; value to update the fourth relationship to obtain the third relationship.
- the formula for calculating the value k of the relationship coefficient includes the fourth formula:
- P N is the rated power of the inverter
- U L is the minimum output voltage of the inverter within the preset range of the rated voltage
- U H is the maximum output voltage of the inverter within the preset range of the rated voltage
- U 1 is the first stable output voltage
- S 2 (U i ) is the apparent power of the load when the output voltage of the inverter is UN.
- controlling the output current of the inverter according to the third correlation relationship and the rated voltage includes: obtaining the target apparent power corresponding to the rated voltage according to the third correlation relationship; The output current of the inverter is controlled.
- the third correlation relationship is used to describe the correlation relationship between the output voltage of the inverter and the apparent power, and the target apparent power corresponding to the rated voltage can be obtained according to the third correlation relationship.
- the apparent power is related to the output voltage and output current
- the current output current of the inverter can be tracked according to the target apparent power, and the drive signal corresponding to the rated voltage can be obtained, and then the inverter can be controlled to operate based on the drive signal. Therefore, by controlling the output voltage of the inverter, the output voltage of the inverter can meet the preset range of the rated voltage, and the control efficiency and the stability of the inverter operation are improved, thereby improving the stability of the load operation.
- the preset frequency includes the rated frequency of the load or the output frequency of the inverter when the energy storage system is in an island state.
- the rated frequency of the load is the frequency suitable for the load to work, and the rated frequency of the load is used as the preset frequency, and the output frequency of the inverter is frozen, so that the output frequency of the inverter is the rated frequency of the load.
- the stability of the load to work The output frequency of the inverter when the energy storage system is in the island state is used as the preset frequency, and the output frequency of the inverter is frozen according to the preset frequency, so that the output frequency of the inverter is the reverse when the energy storage system is in the island state.
- the output frequency of the inverter can be adjusted so that the input frequency of the load does not change in a short period of time, which can improve the stability of the load operation.
- S905 The controller sends a disconnection command to the on-grid mode switch.
- the disconnection instruction is used to instruct the on-grid mode switch to disconnect from the grid corresponding to the on-grid mode switch.
- S906 The on-grid mode switch sends a disconnection completion message to the controller.
- the disconnection completion message is used to indicate that the disconnection of the on-grid mode switch from the grid has been completed.
- S907 The controller sends a switching instruction to the inverter.
- the switching instruction is used to instruct the inverter to switch to the voltage source mode.
- the inverter determines that the energy storage system is in an islanding state, it sends an islanding state message to the controller to disconnect the grid-connected and off-grid mode switch from the grid corresponding to the grid-connected and off-grid mode switch.
- the output frequency of the inverter can also be frozen according to the preset frequency, so as to avoid the occurrence of frequency distortion. There is a negative correlation between the output voltage and the apparent power of the inverter, and the output current of the inverter can be controlled so that the inverter operates stably and the output voltage stably meets the preset range of the rated voltage.
- the controller can send a switching command to the inverter, and the inverter can receive the switching command and determine that it operates stably, and the output voltage meets the pre-specified rated voltage. After setting the range, switch to the voltage source mode to realize the switch between on-grid and off-grid mode, which further improves the stability of the load operation.
- FIG. 10 is another method for switching between on-grid and off-grid modes provided by an embodiment of the present application.
- the method is applied to an energy storage system, and the energy storage system further includes a control Inverter, grid, load, inverter and off-grid mode switch.
- the method includes but is not limited to the following steps S1001-S1010, wherein:
- the inverter determines whether the energy storage system is in an island state.
- step S1001 if it is determined in step S1001 that the energy storage system is in an island state, steps S1002 and S1003 are executed. Otherwise, continue to step S1001.
- S1003 The inverter freezes the output frequency of the inverter according to the preset frequency.
- the inverter controls the output current of the inverter according to the first correlation relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated to obtain a first stable output of the inverter The voltage and the first apparent power corresponding to the first stable output voltage.
- the inverter adjusts the second correlation relationship according to the second correlation relationship in which the output voltage of the inverter and the apparent power of the load are positively correlated, and the magnitude relationship between the first stable output voltage and the rated voltage, to obtain A third relationship in which the output voltage of the inverter and the apparent power of the inverter are negatively correlated.
- the inverter controls the output current of the inverter according to the third correlation relationship and the rated voltage, so that the inverter operates stably, and the output voltage of the inverter meets the preset range of the rated voltage.
- S1007 The controller sends a disconnection command to the on-grid mode switch.
- the disconnection instruction is used to instruct the on-grid mode switch to disconnect from the grid corresponding to the on-grid mode switch.
- S1008 The on-grid mode switch sends a disconnection completion message to the controller.
- the disconnection completion message is used to indicate that the disconnection of the on-grid mode switch from the grid has been completed.
- S1009 The controller sends a switching instruction to the inverter.
- the switching instruction is used to instruct the inverter to switch to the voltage source mode.
- the inverter determines that the energy storage system is in an islanding state, it sends an islanding state message to the controller to disconnect the grid-connected and off-grid mode switch from the grid corresponding to the grid-connected and off-grid mode switch. And after it is determined that the energy storage system is in the island state, the output frequency of the inverter can also be frozen according to the preset frequency, so as to avoid the occurrence of frequency distortion events, and according to the preset range of the rated voltage, the inverter The output voltage of the inverter is negatively correlated with the apparent power of the inverter, and the output current of the inverter is controlled to obtain the first stable output voltage of the inverter and the corresponding first stable output voltage.
- the inverter adjusts the second correlation relationship according to the second correlation relationship in which the output voltage of the inverter and the apparent power of the load are positively correlated, and the magnitude relationship between the first stable output voltage and the rated voltage, to obtain
- the output voltage of the inverter and the apparent power of the inverter are negatively correlated with a third correlation relationship, and then the output current of the inverter is controlled according to the third correlation relationship and the rated voltage, so that the inverter's output current is controlled.
- the output voltage meets the preset range of the rated voltage.
- the first relationship between the output voltage of the inverter and the apparent power of the inverter is adjusted to Improve control efficiency and accuracy.
- the control of the output voltage is realized by controlling the output current, which can further improve the stability of the load operation compared with the direct control of the output voltage.
- the controller can send a switching command to the inverter, and the inverter can receive the switching command and determine that it operates stably, and the output voltage meets the pre-specified rated voltage.
- switch to the voltage source mode to realize the switch between on-grid and off-grid mode, which further improves the stability of the load operation.
- each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may be physically included separately, or two or more units may be integrated into one unit.
- the above-mentioned integrated unit may be implemented in the form of hardware, or may be implemented in the form of hardware plus software functional units.
- the above-mentioned embodiments it may be implemented in whole or in part by software, hardware, firmware or any combination thereof.
- software it can be implemented in whole or in part in the form of a computer program product.
- the computer program product includes one or more computer instructions.
- the computer program instructions when loaded and executed on a computer, result in whole or in part of the processes or functions described herein.
- the computer may be a general purpose computer, special purpose computer, computer network, or other programmable device.
- the computer instructions may be stored in or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions may be downloaded from a website site, computer, server or data center Transmission to another website site, computer, server, or data center by wire (eg, coaxial cable, optical fiber, digital subscriber line) or wireless (eg, infrared, wireless, microwave, etc.).
- the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that includes an integration of one or more available media.
- the usable media may be magnetic media (eg, floppy disks, hard disks, magnetic tapes), optical media (eg, DVD), or semiconductor media (eg, Solid State Disk), and the like.
Abstract
Description
Claims (20)
- 一种储能系统,其特征在于,所述储能系统包括控制器、与所述控制器连接的逆变器和并离网模式开关、与所述并离网模式开关连接的负载,其中:所述逆变器,用于响应于确定所述储能系统处于孤岛状态,向所述控制器发送孤岛状态消息,并根据预设频率对所述逆变器的输出频率进行冻结,根据所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的关联关系,对所述逆变器的输出电流进行控制,以使所述逆变器的输出电压满足额定电压的预设范围;所述控制器,用于基于所述孤岛状态消息向所述并离网模式开关发送断开指令,所述断开指令用于指示所述并离网模式开关与所述并离网模式开关对应的电网断开连接;所述控制器,还用于响应于接收到来自所述并离网模式开关的断开完成消息,向所述逆变器发送切换指令,所述断开完成消息用于指示所述并离网模式开关与所述电网断开连接,所述切换指令用于指示所述逆变器切换为电压源模式;所述逆变器,还用于响应于接收到所述切换指令,且确定所述逆变器的输出电压满足额定电压的预设范围,切换为所述电压源模式。
- 根据权利要求1所述的储能系统,其特征在于,所述逆变器具体用于根据所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第一关联关系,对所述逆变器的输出电流进行控制,得到所述逆变器的第一稳定输出电压和所述第一稳定输出电压对应的第一视在功率,所述第一稳定输出电压的变化范围小于或等于所述预设范围;根据所述逆变器的输出电压和所述负载的视在功率之间成正相关的第二关联关系、所述第一稳定输出电压和额定电压之间的大小关系对所述第一关联关系进行调整,得到所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第三关联关系;根据所述第三关联关系和所述额定电压对所述逆变器的输出电流进行控制,以使所述逆变器的输出电压满足所述额定电压的预设范围。
- 根据权利要求2所述的储能系统,其特征在于,所述逆变器具体用于根据所述第一稳定输出电压和额定电压之间的大小关系对所述第一关联关系进行调整,得到所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第四关联关系;根据所述第四关联关系对所述逆变器的输出电流进行控制,得到所述逆变器的第二稳定输出电压和所述第二稳定输出电压对应的第二视在功率,所述第二稳定输出电压的变化范围小于或等于所述预设范围;根据所述第一稳定输出电压、所述第一视在功率、所述第二稳定输出电压和所述第二视在功率获取所述逆变器的输出电压和所述负载的视在功率之间成正相关的第二关联关系;根据所述第二关联关系、所述第一稳定输出电压和所述额定电压之间的大小关系对所述第四关联关系进行调整,得到所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第三关联关系。
- 根据权利要求2或3所述的储能系统,其特征在于,所述逆变器还用于根据所述逆 变器在所述额定电压的预设范围内的最小输出电压和最大输出电压,以及所述最小输出电压对应的最大视在功率和所述最大输出电压对应的最小视在功率获取所述第一关联关系。
- 根据权利要求3所述的储能系统,其特征在于,所述第四关联关系用于指示当所述第一稳定输出电压小于所述额定电压时,所述第四关联关系中所述逆变器在所述额定电压的预设范围内对应的最大视在功率大于所述第一关联关系中所述逆变器在所述额定电压的预设范围内对应的最大视在功率;当所述第一稳定输出电压大于或等于所述额定电压时,所述第四关联关系中所述逆变器在所述额定电压的预设范围内对应的最大视在功率小于所述第一关联关系中所述逆变器在所述额定电压的预设范围内对应的最大视在功率。
- 根据权利要求3所述的储能系统,其特征在于,所述逆变器具体用于根据所述第二关联关系、所述第一稳定输出电压和所述额定电压之间的大小关系确定所述第四关联关系中的关联系数的取值;根据所述关联系数的取值对所述第四关联关系进行更新,得到所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第三关联关系。
- 根据权利要求2所述的储能系统,其特征在于,所述逆变器具体用于根据所述第三关联关系获取所述额定电压对应的目标视在功率;根据所述目标视在功率对所述逆变器的输出电流进行控制,以使所述逆变器的输出电压满足所述额定电压的预设范围。
- 根据权利要求1-11中任一项所述的储能系统,其特征在于,所述预设频率包括所述负载的额定频率,或所述储能系统处于孤岛状态时所述逆变器的输出频率。
- 根据权利要求1-12中任一项所述的储能系统,其特征在于,所述逆变器具体用于响应于工作模式为电流源模式,根据所述逆变器的输出电压确定所述储能系统是否处于孤岛状态。
- 一种并离网模式切换的方法,其特征在于,应用于储能系统中,所述储能系统包括控制器、逆变器、并离网模式开关、电网和负载,所述方法包括:所述逆变器响应于确定所述储能系统处于孤岛状态,向所述控制器发送孤岛状态消息,并根据预设频率对所述逆变器的输出频率进行冻结,根据所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的关联关系,对所述逆变器的输出电流进行控制,以使所述逆变器的输出电压满足额定电压的预设范围;所述控制器向所述并离网模式开关发送断开指令,所述断开指令用于指示所述并离网模式开关与所述电网断开连接;所述控制器响应于接收到来自所述并离网模式开关的断开完成消息,向所述逆变器发送切换指令,所述断开完成消息用于指示所述并离网模式开关与所述电网断开连接已完成,所述切换指令用于指示所述逆变器切换为电压源模式;所述逆变器响应于接收到所述切换指令,且确定所述逆变器的输出电压满足额定电压的预设范围,切换为所述电压源模式。
- 根据权利要求14所述的方法,其特征在于,所述根据所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的关联关系,对所述逆变器的输出电流进行控制,包括:所述逆变器根据所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第一关联关系,对所述逆变器的输出电流进行控制,得到所述逆变器的第一稳定输出电压和所述第一稳定输出电压对应的第一视在功率,所述第一稳定输出电压的变化范围小于或等于所述预设范围。
- 根据权利要求15所述的方法,其特征在于,所述方法还包括:所述逆变器根据所述逆变器的输出电压和所述负载的视在功率之间成正相关的第二关联关系、所述第一稳定输出电压和额定电压之间的大小关系对所述第一关联关系进行调整,得到所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第三关联关系;所述逆变器根据所述第三关联关系和所述额定电压对所述逆变器的输出电流进行控制,以使所述逆变器的输出电压满足所述额定电压的预设范围。
- 根据权利要求16所述的方法,其特征在于,所述根据所述逆变器的输出电压和所述负载的视在功率之间成正相关的第二关联关系、所述第一稳定输出电压和额定电压之间的大小关系对所述第一关联关系进行调整,得到所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第三关联关系,包括:所述逆变器根据所述第一稳定输出电压和额定电压之间的大小关系对所述第一关联关系进行调整,得到所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第四关联关系;所述逆变器根据所述第四关联关系对所述逆变器的输出电流进行控制,得到所述逆变器的第二稳定输出电压和所述第二稳定输出电压对应的第二视在功率,所述第二稳定输出电压的变化范围小于或等于所述预设范围。
- 根据权利要求17所述的方法,其特征在于,所述方法还包括:所述逆变器根据所述第一稳定输出电压、所述第一视在功率、所述第二稳定输出电压和所述第二视在功率获取所述逆变器的输出电压和所述负载的视在功率之间成正相关的第二关联关系;所述逆变器根据所述第二关联关系、所述第一稳定输出电压和所述额定电压之间的大小关系对所述第四关联关系进行调整,得到所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第三关联关系。
- 根据权利要求15-18中任一项所述的方法,其特征在于,在所述根据所述逆变器的输出电压和所述逆变器的视在功率之间成负相关的第一关联关系,对所述逆变器的输出电 流进行控制之前,所述方法还包括:所述逆变器根据所述逆变器在所述额定电压的预设范围内的最小输出电压和最大输出电压,以及所述最小输出电压对应的最大视在功率和所述最大输出电压对应的最小视在功率获取所述第一关联关系。
- 根据权利要求17所述的方法,其特征在于,所述第四关联关系用于指示当所述第一稳定输出电压小于所述额定电压时,所述第四关联关系中所述逆变器在所述额定电压的预设范围内对应的最大视在功率大于所述第一关联关系中所述逆变器在所述额定电压的预设范围内对应的最大视在功率;当所述第一稳定输出电压大于或等于所述额定电压时,所述第四关联关系中所述逆变器在所述额定电压的预设范围内对应的最大视在功率小于所述第一关联关系中所述逆变器在所述额定电压的预设范围内对应的最大视在功率。
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