CN114142503A - Unplanned microgrid grid-connected and off-grid switching method, energy management system and storage medium - Google Patents
Unplanned microgrid grid-connected and off-grid switching method, energy management system and storage medium Download PDFInfo
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- CN114142503A CN114142503A CN202111258341.5A CN202111258341A CN114142503A CN 114142503 A CN114142503 A CN 114142503A CN 202111258341 A CN202111258341 A CN 202111258341A CN 114142503 A CN114142503 A CN 114142503A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E70/00—Other energy conversion or management systems reducing GHG emissions
- Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
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- Supply And Distribution Of Alternating Current (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention provides an unplanned microgrid grid-connected and off-grid switching method, an energy management system and a storage medium, wherein the method comprises the following steps: monitoring the commercial power in real time; when the mains supply power failure is monitored, controlling each energy storage converter to stop and controlling the first contactor to be disconnected; then controlling each energy storage converter to be switched from a PQ mode to a VSG mode; and controlling the energy storage converters to be parallel-connected and started in the VSG mode. Through the scheme, the energy storage converters can be switched in parallel and off-grid mode when the mains supply power failure is monitored, so that the stable operation of the micro-grid system is guaranteed.
Description
Technical Field
The invention relates to the technical field of photovoltaic grid connection, in particular to an unplanned microgrid grid-connected and off-grid switching method, an energy management system and a storage medium.
Background
The PCS (Power Conversion System) has two working modes, a grid-connected mode and an off-grid mode. When the power grid is normal, the PCS and the power grid play a role in supplying power to the load. When the power grid is abnormal, the PCS is separated from the power grid to operate independently and supplies power to the load independently. And during grid-connected work, the PCS adopts a grid-connected mode PQ control, is equivalent to a current source, and outputs power under the conditions of following the voltage and frequency of a power grid. When the off-grid work is carried out, the PCS is controlled by an off-grid mode VF, and is equivalent to a voltage source, so that the load power is ensured under the condition of providing voltage and frequency support for the load.
The PCS can not switch the working mode at will when working, if the mains supply is abnormal when the PCS is in grid-connected work, the PCS cannot detect the fault in time, the PCS is not switched into the off-grid working mode, the fault is reported, and the load is shut down possibly at the moment. If the PCS supplies power to the load independently during off-grid operation, the load is required to be disconnected from the power grid, otherwise, the output voltage of the PCS and the mains voltage are connected together under the condition that the phase amplitudes are different, and equipment can be damaged.
Disclosure of Invention
In view of this, the invention provides an unplanned microgrid grid-connected and off-grid switching method, an energy management system and a storage medium, which can solve the problem that the microgrid system grid-connected and off-grid switching is not timely due to unplanned power failure.
In a first aspect, an embodiment of the present invention provides an unplanned microgrid grid-connected and off-grid switching method, which is applied to a microgrid system, where the microgrid system includes a first contactor, at least one photovoltaic energy storage device, and at least one energy storage converter; the photovoltaic energy storage devices correspond to the energy storage converters one by one;
the first contactor is connected between a mains supply and a first bus, the first bus is connected with an optical storage bus, the optical storage bus is respectively connected with each energy storage converter, each energy storage converter is respectively connected with a corresponding photovoltaic energy storage device, and the first bus is also used for connecting a load;
the method comprises the following steps:
monitoring the commercial power in real time;
if the mains supply power failure is monitored, controlling each energy storage converter to stop and controlling the first contactor to be disconnected;
controlling each energy storage converter to be switched from a PQ mode to a VSG mode; and controlling the energy storage converters to be parallel-connected and started in the VSG mode.
In a second aspect, an embodiment of the present invention provides an energy management system, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the method according to any one of the possible implementation manners of the first aspect when executing the computer program.
In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processor, the computer program implements the steps of the method according to any one of the possible implementation manners of the first aspect.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
the embodiment of the invention monitors the commercial power in real time; when the mains supply power failure is monitored, each energy storage converter can be controlled to stop, and the first contactor is controlled to be disconnected; then controlling each energy storage converter to be switched from a PQ mode to a VSG mode; and controlling the energy storage converters to be parallel-connected and started in the VSG mode. Through the scheme, the embodiment can timely carry out grid-connected and off-grid switching on all the energy storage converters when monitoring the power failure of the mains supply, so that the stable operation of the microgrid system is ensured.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is an application scenario diagram of an unscheduled piconet parallel-to-offline switching method according to an embodiment of the present invention;
fig. 2 is a flowchart illustrating an implementation of an unscheduled piconet switching method on a grid-connected basis according to an embodiment of the present invention;
fig. 3 is a flowchart illustrating a process of implementing a grid-connected to off-grid conversion of a microgrid system according to an embodiment of the present invention;
fig. 4 is a flow chart of implementation of off-grid to on-grid conversion of the microgrid system provided by the embodiment of the present invention;
fig. 5 is a schematic structural diagram of an unplanned piconet switching apparatus according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of an energy management system provided by an embodiment of the invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description is made by way of specific embodiments with reference to the accompanying drawings.
Fig. 1 is a circuit diagram of a microgrid system according to an embodiment of the present invention. As shown in fig. 1, the microgrid system comprises a first contactor K1, at least one photovoltaic energy storage device and at least one energy storage converter PCS; the photovoltaic energy storage devices correspond to the energy storage converters one by one;
the first contactor K1 is connected between commercial power and a first bus, the first bus is connected with a light storage bus, the light storage bus is connected with each energy storage converter PCS respectively, each energy storage converter PCS is connected with a corresponding photovoltaic energy storage device respectively, and the first bus is also used for connecting a load.
In this embodiment, the first bus may be an emergency bus with a continuous power-off requirement.
As shown in fig. 2, fig. 2 shows an implementation flow of the unscheduled piconet switching method on the grid-connected basis and off-grid basis provided in this embodiment, and a process thereof is detailed as follows:
s101: monitoring the commercial power in real time;
s102: if the mains supply power failure is monitored, controlling each energy storage converter to stop and controlling the first contactor to be disconnected;
s103: controlling each energy storage converter to be switched from a PQ mode to a VSG mode; and controlling the energy storage converters to be parallel-connected and started in the VSG mode.
The execution main body of the embodiment may be an energy management system EMS, and the EMS may implement unified control of each device in the microgrid system.
Specifically, the EMS monitors whether the mains supply is normal or not in real time through the electric energy monitoring device, if the mains supply is suddenly cut off, each energy storage converter PCS can immediately enter an island protection state, and at the moment, the microgrid system needs to be switched from a grid-connected state to an off-grid state. In the process of switching from a grid-connected state to an off-grid state, an EMS first controls a first contactor K1 to be turned off, after the first contactor K1 is turned off, in the prior art, a controller of an energy storage converter is usually directly switched from a PQ mode to a VF mode and then started, and when a plurality of energy storage converters exist, the above process is difficult to realize.
Through the process, the grid-connected to off-grid process of the microgrid system with the plurality of energy storage converters can be realized when the commercial power is in unplanned power failure.
As can be seen from the above embodiments, the embodiment of the present invention monitors the commercial power in real time; when the mains supply power failure is monitored, each energy storage converter can be controlled to stop, and the first contactor is controlled to be disconnected; then controlling each energy storage converter to be switched from a PQ mode to a VSG mode; and controlling the energy storage converters to be parallel-connected and started in the VSG mode. Through the scheme, the embodiment can timely carry out grid-connected and off-grid switching on all the energy storage converters when monitoring the power failure of the mains supply, so that the stable operation of the microgrid system is ensured.
In one embodiment, the specific implementation flow of S103 includes:
and controlling any energy storage converter to start, and controlling other energy storage converters except the energy storage converter to start after the energy storage converter is started so as to enable the other energy storage converters except the energy storage converter to be parallel to the energy storage converter.
In the embodiment, the parallel startup of all the energy storage converters is controlled to make the output voltages, the frequencies and the phases of all the energy storage converters consistent.
In one embodiment, the specific implementation flow of S102 includes:
and if the energy storage converters are monitored to enter an island protection state after the mains supply is powered off, controlling the energy storage converters to stop.
In this embodiment, in the prior art, when the energy storage converter monitors the power failure of the utility power, the energy storage converter is automatically switched to an island protection state.
In one embodiment, the microgrid system comprises a photovoltaic power generation device and a photovoltaic inverter INV, wherein the photovoltaic power generation device is connected with the light storage bus through the photovoltaic inverter INV;
after S103, the method provided in this embodiment further includes:
and controlling the photovoltaic inverter to start so that the photovoltaic inverter is connected with all the energy storage converters in parallel.
In the implementation, after monitoring that all the energy storage converters are started, the energy management system controls the photovoltaic inverter to be started, and the photovoltaic inverter controls the output power of the photovoltaic inverter to gradually increase from zero after being started until the output voltage, frequency and phase of the photovoltaic inverter are consistent with those of all the energy storage converters, so that the parallel operation process with all the energy storage converters is realized.
In one embodiment, after controlling the photovoltaic inverter to start, the method provided by this embodiment further includes:
monitoring the residual electric quantity of the photovoltaic energy storage device;
if the residual electric quantity of the photovoltaic energy storage device is larger than a first preset threshold value, switching the control right of the photovoltaic inverter into a first control right, determining the output power of the photovoltaic inverter according to the residual electric quantity of the photovoltaic energy storage device under the first control right, wherein the residual electric quantity and the output power of the photovoltaic inverter are in an inverse proportional relation;
if the residual electric quantity of the photovoltaic energy storage device is smaller than the first preset threshold value, switching the control right of the photovoltaic inverter to a second control right, and sending a self-running instruction to the photovoltaic inverter under the second control right so that the photovoltaic inverter can automatically control the running state.
In this embodiment, after the microgrid system is switched from grid-connected to off-grid, the energy management system determines to which the controller of the photovoltaic inverter belongs according to the residual electric quantity of the photovoltaic energy storage device.
Specifically, the first preset threshold may be 80%, and if the remaining power (SOC) is less than the first preset threshold, the control right Of the photovoltaic inverter is the second control right, and under the second control right, the photovoltaic inverter automatically determines how to control the operation State Of the photovoltaic inverter. Typically, the pv inverter operates in a Maximum Power Point Tracking (MPPT) mode. If the residual electric quantity is greater than or equal to the first preset threshold value, the control right of the photovoltaic inverter is the first control right, namely the control right is in the energy management system, at the moment, the energy management system linearly controls the output power of the photovoltaic inverter according to the residual electric quantity of the photovoltaic energy storage device, the more the residual electric quantity is, the less the output power of the photovoltaic inverter is, and therefore when the residual electric quantity of the photovoltaic energy storage device is more, power is preferentially supplied to a load through the photovoltaic energy storage device.
Through the process, the energy flow direction of the whole micro-grid system can be comprehensively planned through the energy management system according to the residual electric quantity of the photovoltaic energy storage device, and therefore the energy utilization rate of the micro-grid system is improved.
In one embodiment, the microgrid system further comprises a second contactor, a third contactor and a first generator set; the first generator set is a generator set which generates electricity by utilizing other energy sources except photovoltaic;
the second contactor is connected between the light storage bus and the first bus;
the first generator set is connected with the first bus through the third contactor;
the method provided by the embodiment further comprises the following steps:
if the residual electric quantity of the photovoltaic energy storage device is smaller than a second preset threshold value, controlling the second contactor to be disconnected;
controlling the first generator set to start, and closing the third contactor after monitoring that the first generator set is started;
if the residual electric quantity of the photovoltaic energy storage device is larger than a third preset threshold value, the third contactor is controlled to be disconnected, the first generator set is controlled to stop, and the second contactor is controlled to be closed;
the third preset threshold is greater than the second preset threshold and less than the first preset threshold.
In this embodiment, the first generator set may be a diesel generator set, a gas generator set, or other energy generator sets besides photovoltaic power generation.
Specifically, the second preset threshold may be 20%, and the third preset threshold may be 50%.
In an embodiment, after S103, the method provided in this embodiment further includes a control process of switching the grid-connected power generation system from off-grid to on-grid after the utility power is restored, which is detailed as follows:
s104: and if the mains supply is monitored to be recovered, controlling the first contactor to be closed, and controlling each energy storage converter to be switched from a VSG mode to a PQ mode.
In this embodiment, when the utility power is monitored to be recovered, the first contactor K1 is controlled to be closed first, and then each energy storage converter PCS is controlled to be switched from the VSG mode to the PQ mode.
In one embodiment, the specific implementation flow of S104 includes:
if the mains supply recovery is monitored, performing synchronous control on each energy storage converter and the mains supply;
and controlling the first contactor to be closed, and controlling each energy storage converter to be switched from a VSG mode to a PQ mode.
Specifically, if the microgrid system comprises a photovoltaic power generation device and a photovoltaic inverter, the energy management system monitors that the mains supply is recovered, and then controls each energy storage converter, the photovoltaic inverter and the mains supply in a synchronous manner.
Specifically, the synchronous control is to control the voltage, frequency and phase of the photovoltaic inverter and the energy storage converter to be consistent with the power grid.
In one embodiment, the microgrid system further comprises a second contactor, a third contactor and a first generator set; the first generator set is a generator set which generates electricity by utilizing other energy sources except photovoltaic;
the second contactor is connected between the light storage bus and the first bus; the first generator set is connected with the first bus through the third contactor.
In this embodiment, if the microgrid system includes the first generator set, when the utility power restoration is monitored, the current operating state of the microgrid system in the off-grid mode is checked at first, whether the first generator set works or the photovoltaic power generation device works is judged, and different flows of switching from off-grid to grid-connected are adopted according to different operating states. Specifically, the specific implementation flow of S104 includes:
if the fact that the second contactor is in a closed state and the third contactor is in an open state when the mains supply is monitored to be recovered, controlling the first contactor to be closed, and controlling each energy storage converter to be switched from a VSG mode to a PQ mode;
if the fact that the second contactor is in an open state and the third contactor is in a closed state when the mains supply recovery is monitored, the third contactor is controlled to be opened and the first contactor is controlled to be closed successively;
controlling the photovoltaic inverter and each energy storage converter to stop, and switching each energy storage converter into a PQ mode;
and controlling the second contactor to be closed, and starting each energy storage converter and the photovoltaic inverter so as to enable the microgrid system to enter a grid-connected operation mode.
As shown in fig. 3, as a specific application scenario of the embodiment, the embodiment provides an implementation process of converting a grid-connected state to a grid-disconnected state of a microgrid system, and a process thereof is detailed as follows:
s1: if the energy management system monitors that the commercial power is cut off, jumping to S2;
s2: the photovoltaic inverter and the energy storage converter automatically enter an island protection state after monitoring the mains supply power failure, and the operation is switched to S3;
s3: the energy management system controls the first contactor K1 to be opened, and the S3 is jumped to;
s4: the energy management system controls all the energy storage converters to be switched into a VSG mode and started, and the S5 is skipped;
s5: the energy management system controls the photovoltaic inverter INV to start and jumps to S6;
s6: the energy management system judges whether the SOC of the photovoltaic energy storage device is less than 10%, if so, the step is switched to S7, and if not, the step is switched to S9;
s7: the energy management system controls all the energy storage converters to stop and jumps to S8;
s8: and turning to black start.
S9: the energy management system judges whether the SOC of the photovoltaic energy storage device is less than 20%, if so, the step is switched to S10, and if not, the step is switched to S17;
s10: the energy management system opens the second contactor K2 and jumps to S11;
s11: the energy management system controls the first generator set to start, and skips to S12 after monitoring that the first generator set is started;
s12: the energy management system controls the third contactor K3 to be closed and jumps to S13;
s13: the energy management system judges whether the SOC of the photovoltaic energy storage device is larger than 50%, if so, the step is carried out to S14, and if not, the step is carried out to S6;
s14: the energy management system opens the third contactor K3 and jumps to S15;
s15: the energy management system controls the first generator set to stop, and the step goes to S16;
s16: the energy management system closes the second contactor K2 and jumps to S19;
s17: the energy management system judges whether the SOC of the photovoltaic energy storage device is less than 25%, if so, the step is switched to S18, and if not, the step is switched to S19;
s18: the energy management system sends out audible and visual alarm signals;
s19: the energy management system judges whether the SOC of the photovoltaic energy storage device is less than 80%, if so, the step is switched to S20, and if not, the step is switched to S21;
s20: the control right is switched to a second control right, and the photovoltaic inverter automatically controls the running state of the photovoltaic inverter;
s21: and switching the control right to a first control right, and controlling the output power of the photovoltaic inverter by the energy management system according to the SOC of the photovoltaic energy storage device under the first control right.
In an embodiment of the present invention, the off-grid to on-grid process of the microgrid system is as follows:
s01: if the energy management system monitors that the commercial power is recovered, jumping to S02;
s02: the energy management system judges whether the current running state is K2 closed and K3 open; if yes, jumping to S04, and if not, jumping to S03;
s03: the energy management system judges whether the current running state is K3 closed and K2 open; if yes, go to S09;
s04: the energy management system controls the PCS and the INV to synchronize with the power grid through a synchronization controller, and skips to S05;
s05: the energy management system judges whether the synchronization is finished, if so, the step goes to S06, and if not, the step goes to S04;
s06: the energy management system controls the first contactor K1 to be closed and jumps to S07;
s07: the energy management system controls each PCS to be switched from a VSG mode to a PQ mode, and the operation goes to S08;
s08: entering a grid-connected operation mode;
s09: the energy management system controls the third contactor K3 to be disconnected and jumps to S010;
s010: the energy management system controls the first contactor K1 to be closed and jumps to S011;
s011: the energy management system closes INV and PCS, controls PCS to be switched into a PQ mode, and skips to S012;
s012: the energy management system controls the second contactor K2 to be closed and jumps to S013;
s013: the energy management system turns on PCS and INV and jumps to S08.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
The following are embodiments of the apparatus of the invention, reference being made to the corresponding method embodiments described above for details which are not described in detail therein.
Fig. 5 is a schematic structural diagram of an unplanned microgrid on-grid and off-grid switching apparatus 100 according to an embodiment of the present invention, which is applied to a microgrid system including a first contactor, at least one photovoltaic energy storage device and at least one energy storage converter; the photovoltaic energy storage devices correspond to the energy storage converters one by one;
the first contactor is connected between a mains supply and a first bus, the first bus is connected with a light storage bus, the light storage bus is respectively connected with each energy storage converter, each energy storage converter is respectively connected with a corresponding photovoltaic energy storage device, and the first bus is also used for connecting a load. For convenience of explanation, the apparatus provided in this embodiment only shows the parts related to the embodiment of the present invention, and the details are as follows:
the commercial power monitoring module 110 is used for monitoring commercial power in real time;
the shutdown module 120 is configured to control each energy storage converter to shutdown and control the first contactor to be disconnected if the mains supply power failure is monitored;
an off-grid parallel operation starting module 130, configured to control each energy storage converter to switch from the PQ mode to the VSG mode; and controlling the energy storage converters to be parallel-connected and started in the VSG mode.
In one embodiment, the off-grid parallel start module 130 is specifically configured to:
and controlling any energy storage converter to start, and controlling other energy storage converters except the energy storage converter to start after the energy storage converter is started so as to enable the other energy storage converters except the energy storage converter to be parallel to the energy storage converter.
In one embodiment, shutdown module 120 is specifically configured to:
and if the energy storage converters are monitored to enter an island protection state after the mains supply is powered off, controlling the energy storage converters to stop.
In one embodiment, the unplanned microgrid grid-connected and grid-disconnected switching apparatus 100 further includes a grid-disconnected switching module configured to:
and if the mains supply is monitored to be recovered, controlling the first contactor to be closed, and controlling each energy storage converter to be switched from a VSG mode to a PQ mode.
In one embodiment, the microgrid system comprises a photovoltaic power generation device and a photovoltaic inverter, wherein the photovoltaic power generation device is connected with the optical storage bus through the photovoltaic inverter;
the unplanned microgrid grid-connected and off-grid switching apparatus 100 further includes an inverter parallel operation module configured to:
and controlling the photovoltaic inverter to start so that the photovoltaic inverter is connected with all the energy storage converters in parallel.
In one embodiment, the unplanned microgrid grid-connected and off-grid switching apparatus 100 further comprises a photovoltaic inverter control module for:
monitoring the residual electric quantity of the photovoltaic energy storage device;
if the residual electric quantity of the photovoltaic energy storage device is larger than a first preset threshold value, switching the control right of the photovoltaic inverter into a first control right, determining the output power of the photovoltaic inverter according to the residual electric quantity of the photovoltaic energy storage device under the first control right, wherein the residual electric quantity and the output power of the photovoltaic inverter are in an inverse proportional relation;
if the residual electric quantity of the photovoltaic energy storage device is smaller than the first preset threshold value, switching the control right of the photovoltaic inverter to a second control right, and sending a self-running instruction to the photovoltaic inverter under the second control right so that the photovoltaic inverter can automatically control the running state.
In one embodiment, the microgrid system further comprises a second contactor, a third contactor and a first generator set; the first generator set is a generator set which generates electricity by utilizing other energy sources except photovoltaic;
the second contactor is connected between the light storage bus and the first bus;
the first generator set is connected with the first bus through the third contactor;
the unplanned microgrid grid-connected and off-grid switching device 100 further comprises a grid-connected device switching module, which is specifically configured to:
if the residual electric quantity of the photovoltaic energy storage device is smaller than a second preset threshold value, controlling the second contactor to be disconnected;
controlling the first generator set to start, and closing the third contactor after monitoring that the first generator set is started;
if the residual electric quantity of the photovoltaic energy storage device is larger than a third preset threshold value, the third contactor is controlled to be disconnected, the first generator set is controlled to stop, and the second contactor is controlled to be closed;
the third preset threshold is greater than the second preset threshold and less than the first preset threshold.
In one embodiment, the off-grid and on-grid switching module specifically includes:
if the mains supply recovery is monitored, performing synchronous control on each energy storage converter and the mains supply;
and controlling the first contactor to be closed, and controlling each energy storage converter to be switched from a VSG mode to a PQ mode.
Fig. 6 is a schematic diagram of an energy management system according to an embodiment of the invention. As shown in fig. 6, the energy management system 6 of this embodiment includes: a processor 60, a memory 61 and a computer program 62 stored in said memory 61 and executable on said processor 60. The processor 60, when executing the computer program 62, implements the steps of the above-described various embodiments of the unplanned piconet switch off-grid method, such as the steps 101 to 103 shown in fig. 2. Alternatively, the processor 60, when executing the computer program 62, implements the functions of the modules/units in the above-mentioned device embodiments, such as the functions of the units 110 to 130 shown in fig. 5.
Illustratively, the computer program 62 may be partitioned into one or more modules/units that are stored in the memory 61 and executed by the processor 60 to implement the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 62 in the energy management system 6.
The energy management system 6 may include, but is not limited to, a processor 60, a memory 61. Those skilled in the art will appreciate that fig. 6 is merely an example of an energy management system 6 and does not constitute a limitation of energy management system 6 and may include more or fewer components than shown, or some components in combination, or different components, e.g., the energy management system may also include input output devices, network access devices, buses, etc.
The Processor 60 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage 61 may be an internal storage unit of the energy management system 6, such as a hard disk or a memory of the energy management system 6. The memory 61 may also be an external storage device of the energy management system 6, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like, provided on the energy management system 6. Further, the memory 61 may also include both an internal storage unit of the energy management system 6 and an external storage device. The memory 61 is used for storing the computer programs and other programs and data required by the energy management system. The memory 61 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided herein, it should be understood that the disclosed device/energy management system and method may be implemented in other ways. For example, the above-described device/energy management system embodiments are merely illustrative, and for example, the division of the modules or units is only one logical division, and other divisions may be realized in practice, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the processes in the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the embodiments of the method for unscheduled piconet switching from a piconet to an off piconet may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain other components which may be suitably increased or decreased as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media which may not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. The unplanned microgrid grid-connected and off-grid switching method is applied to a microgrid system, wherein the microgrid system comprises a first contactor, at least one photovoltaic energy storage device and at least one energy storage converter; the photovoltaic energy storage devices correspond to the energy storage converters one by one;
the first contactor is connected between a mains supply and a first bus, the first bus is connected with an optical storage bus, the optical storage bus is respectively connected with each energy storage converter, each energy storage converter is respectively connected with a corresponding photovoltaic energy storage device, and the first bus is also used for connecting a load;
the method comprises the following steps:
monitoring the commercial power in real time;
if the mains supply power failure is monitored, controlling each energy storage converter to stop and controlling the first contactor to be disconnected;
controlling each energy storage converter to be switched from a PQ mode to a VSG mode; and controlling the energy storage converters to be parallel-connected and started in the VSG mode.
2. The unplanned microgrid grid-connected and off-grid switching method according to claim 1, wherein the controlling of parallel startup of each energy storage converter in a VSG mode comprises:
and controlling any energy storage converter to start, and controlling other energy storage converters except the energy storage converter to start after the energy storage converter is started so as to enable the other energy storage converters except the energy storage converter to be parallel to the energy storage converter.
3. The unplanned microgrid grid-connected and off-grid switching method of claim 1, wherein if a mains power failure is monitored, each energy storage converter is controlled to be shut down, and the method comprises the following steps:
and if the energy storage converters are monitored to enter an island protection state after the mains supply is powered off, controlling the energy storage converters to stop.
4. The unplanned microgrid grid-connected and off-grid switching method of claim 1, wherein after the controlling of the parallel startup of the respective energy storage converters in the VSG mode, the method further comprises:
and if the mains supply is monitored to be recovered, controlling the first contactor to be closed, and controlling each energy storage converter to be switched from a VSG mode to a PQ mode.
5. The unplanned microgrid grid-on and grid-off switching method of claim 1, wherein the microgrid system comprises a photovoltaic power generation device and a photovoltaic inverter, the photovoltaic power generation device is connected with the optical storage bus through the photovoltaic inverter;
after the controlling of the parallel start of the energy storage converters in the VSG mode, the method further includes:
and controlling the photovoltaic inverter to start so that the photovoltaic inverter is connected with all the energy storage converters in parallel.
6. The unplanned microgrid grid-on and off-grid switching method of claim 5, wherein after the controlling the photovoltaic inverter to start, the method further comprises:
monitoring the residual electric quantity of the photovoltaic energy storage device;
if the residual electric quantity of the photovoltaic energy storage device is larger than a first preset threshold value, switching the control right of the photovoltaic inverter into a first control right, determining the output power of the photovoltaic inverter according to the residual electric quantity of the photovoltaic energy storage device under the first control right, wherein the residual electric quantity and the output power of the photovoltaic inverter are in an inverse proportional relation;
if the residual electric quantity of the photovoltaic energy storage device is smaller than the first preset threshold value, switching the control right of the photovoltaic inverter to a second control right, and sending a self-running instruction to the photovoltaic inverter under the second control right so that the photovoltaic inverter can automatically control the running state.
7. The unplanned microgrid grid-on-grid and off-grid switching method of any one of claims 1 to 6, wherein the microgrid system further comprises a second contactor, a third contactor and a first generator set; the first generator set is a generator set which generates electricity by utilizing other energy sources except photovoltaic;
the second contactor is connected between the light storage bus and the first bus;
the first generator set is connected with the first bus through the third contactor;
the method further comprises the following steps:
if the residual electric quantity of the photovoltaic energy storage device is smaller than a second preset threshold value, controlling the second contactor to be disconnected;
controlling the first generator set to start, and closing the third contactor after monitoring that the first generator set is started;
if the residual electric quantity of the photovoltaic energy storage device is larger than a third preset threshold value, the third contactor is controlled to be disconnected, the first generator set is controlled to stop, and the second contactor is controlled to be closed;
the third preset threshold is greater than the second preset threshold and less than the first preset threshold.
8. The unplanned microgrid grid-connected and off-grid switching method of claim 4, wherein if commercial power restoration is monitored, controlling the first contactor to be closed and controlling each energy storage converter to be switched from a VSG mode to a PQ mode comprises:
if the mains supply recovery is monitored, performing synchronous control on each energy storage converter and the mains supply;
and controlling the first contactor to be closed, and controlling each energy storage converter to be switched from a VSG mode to a PQ mode.
9. An energy management system comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of the preceding claims 1 to 8 when executing the computer program.
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 8.
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