CN116470523A - Regional power grid off-grid control method and device, storage medium and regional power grid system - Google Patents
Regional power grid off-grid control method and device, storage medium and regional power grid system Download PDFInfo
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Classifications
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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
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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
- H02J3/002—Flicker reduction, e.g. compensation of flicker introduced by non-linear load
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—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
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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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
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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
- 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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- 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
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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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
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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
- H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
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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
- H02J2300/40—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation wherein a plurality of decentralised, dispersed or local energy generation technologies are operated simultaneously
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The invention discloses a regional power grid off-grid control method and device, a storage medium and a regional power grid system, wherein the method comprises the following steps: acquiring real-time electric energy parameter data on the connecting lines, the photovoltaic unit access lines, the energy storage unit access lines and each distribution branch line, and calculating real-time power on each corresponding line; when the tie line power is 0 and the regional power grid runs off-grid, calculating the power shortage of the regional power grid after off-grid according to the real-time power of each line; and if the regional power grid power shortage is not 0, acquiring the running state information of the energy storage unit, and performing power regulation control on at least one of the photovoltaic unit, the energy storage unit and the regional load according to a preset regional power transmission power control strategy or a regional power absorption power control strategy according to the tie line power direction corresponding to the regional power grid power shortage and the running state of the energy storage unit. The invention realizes safe and stable control at off-grid moment through coordination control of multiple energy sources, and ensures smooth transition when the operation mode of the regional power grid is switched.
Description
Technical Field
The invention relates to the technical field of automatic control of power systems, in particular to a regional power grid off-grid control method and device, a storage medium and a regional power grid system.
Background
With rapid development of new energy control technology, energy storage control technology and load technology in recent years, a large number of power electronic equipment such as distributed renewable energy power generation and the like are connected to regional power grids, and a new energy high-permeability regional power grid is built and mainly comprises a sea island power grid and the like, wherein renewable energy installation occupies more power grid terminals, and is weakly connected with a large power grid. In order to ensure that the regional power grid can safely and reliably operate in overhauling or abnormal conditions, the regional power grid is required to have off-grid operation capability.
Regional power grid operation generally has two modes of operation: in a grid-connected operation mode, the regional power grid exchanges power with the main power grid through a connecting wire, and the voltage and the frequency of the power grid can be basically kept stable due to the clamping effect of the main power grid, so that the normal power supply of a load is ensured; and the second is that when the power grid fails or the interconnecting link needs to be overhauled, the regional power grid needs to disconnect the interconnecting link from the large power grid and enter a isolated network operation mode. Therefore, how to realize the fast and stable switching of the regional power grid when the interconnecting line fails is a problem to be studied, and in order to ensure that the switching process does not generate larger impact on the regional power grid, a reasonable control strategy must be adopted to realize the smooth transition of the switching process.
At present, the technology of island operation control of a regional power grid is mainly concentrated on a micro-grid and off-grid conversion, the micro-grid off-grid instant switching control strategy ensures the stable operation of the micro-grid, the control strategy is mainly concentrated on an inverter control layer, such as droop control, constant voltage-constant frequency control, constant power control, virtual synchronous machine and the like, but the research on how to regulate and control a power supply in the micro-grid is lacking.
Disclosure of Invention
The invention aims to provide a regional power grid off-grid control method and device, a storage medium and a regional power grid system, aiming at a regional power grid containing multiple power sources, safety and stability control at off-grid moment is realized through coordination control of multiple energy sources, the stability of the frequency inside the system is maintained, and smooth transition during switching of the operation modes of the regional power grid is ensured. The technical scheme adopted by the invention is as follows.
In one aspect, the invention provides a regional power grid off-grid control method, wherein the regional power grid comprises a main line, a gas turbine, a photovoltaic unit, an energy storage unit and a distribution branch line, wherein the gas turbine, the photovoltaic unit, the energy storage unit and the distribution branch line are connected with the main line, the main line is connected with the photovoltaic unit and the energy storage unit through a tie-line tie switch, the photovoltaic unit and the energy storage unit are respectively connected with the main line through intelligent circuit breakers, and the distribution branch line is connected with regional load through the intelligent circuit breakers; the control method comprises the following steps:
acquiring real-time electric energy parameter data on the interconnection line, the photovoltaic unit access line, the energy storage unit access line and each distribution branch line;
calculating real-time power on each corresponding line according to the acquired electric energy parameter data;
when the power of the tie line is 0, the regional power grid runs off the grid, and the power shortage of the regional power grid after off the grid is calculated according to the real-time power on the photovoltaic unit access line, the energy storage unit access line and each distribution branch line;
and if the regional power grid power shortage is not 0, acquiring the running state information of the energy storage unit, and performing power regulation control on at least one of the photovoltaic unit, the energy storage unit and the regional load according to a preset regional power transmission control strategy or a regional power absorption control strategy according to the tie line power direction corresponding to the regional power shortage and the running state information of the energy storage unit.
Optionally, the method further comprises: and receiving the external main power grid fault overhaul notification information, and controlling the disconnection of the tie switch in response to the information so that the tie line power is 0 and the regional power grid operates off-grid. After the tie switch is controlled to be disconnected, the maximum delay time of disconnection of the tie line is considered, the power of the regional power grid can be judged to be 0 through detecting the electric energy parameter on the tie line, namely the actual off-grid moment, and off-grid control logic is executed after the regional power grid is actually off-grid.
Optionally, calculating the power shortage of the off-grid regional power grid according to the real-time power on the photovoltaic unit access line, the energy storage unit access line and each distribution branch line, wherein the formula is as follows:
wherein P is hot Is the active power output of the gas turbine, P pv Is the active power output of each photovoltaic subunit, N is the number of the photovoltaic subunits and P bat Is the active power output of each energy storage subunit, M is the number of the energy storage subunits, P load The load units consume the work power, and K is the number of regional load units.
According to the above formula, if the regional power grid power deficiency Δp is 0, no power exchange is represented on the tie line, and no regional power grid power adjustment is needed.
Optionally, according to a preset power control policy for regional network delivery or a power control policy for regional network absorption, the power control method for at least one of the photovoltaic unit, the energy storage unit and the regional load includes:
judging the power direction of the connecting line according to the power shortage of the regional power grid, wherein if delta P is more than 0, the power direction of the connecting line is the power transmission direction of the regional power grid, and if delta P is less than 0, the power direction of the connecting line is the power absorption direction of the regional power grid;
selecting a control strategy as a corresponding area network outgoing power control strategy or an area network absorption power control strategy according to the judging result of the tie line power direction;
determining an object participating in power regulation in a control strategy according to the running state information of the energy storage unit;
and carrying out power regulation on the determined power regulation object according to the selected control strategy so that the power shortage delta P of the regional power grid after the power regulation is 0.
Optionally, the determining the object participating in power adjustment in the control policy according to the operation state information of the energy storage unit includes:
a) In the area network outgoing power control strategy: if it is storedEnergy storage adjustable power delta P with energy SOC more than 0.9 bat =0, then the power conditioning object is a photovoltaic unit; if the energy storage SOC is less than or equal to 0.9 and the energy storage adjustable power delta P bat The power regulation object is an energy storage unit if the power is more than or equal to delta P; if the energy storage SOC is less than or equal to 0.9 and the energy storage adjustable power delta P bat The power regulation object is a photovoltaic unit and an energy storage unit;
b) In the area network absorption power control strategy: if the energy storage SOC is less than 0.1 and the energy storage adjustable power delta P bat =0, then the power adjustment object is the zone load; if the energy storage SOC is more than or equal to 0.1 and the energy storage adjustable power delta P bat The power regulation object is an energy storage unit if the power is more than or equal to delta P; if the energy storage SOC is more than or equal to 0.1 and the energy storage adjustable power delta P bat And < [ delta ] P, the power regulation object is an energy storage unit and a regional load.
Optionally, performing power adjustment on the determined power adjustment object according to the selected control policy, so that the power-adjusted regional power grid power deficiency Δp is 0, including:
in the area network power delivery state, according to an area network delivery power control strategy: if the energy storage SOC is more than 0.9 and delta P bat =0, then the power deficit is distributed to each photovoltaic subunit, and the output is reduced by the photovoltaic subunit cutting machine so that Δp is reduced to 0; if the energy storage SOC is less than or equal to 0.9 and delta P bat More than or equal to DeltaP, distributing the power shortage to each energy storage subunit, and reducing DeltaP to 0 by absorbing power by the energy storage subunits; if the energy storage SOC is less than or equal to 0.9 and the energy storage adjustable power delta P bat The power deficiency is distributed to each photovoltaic unit and each energy storage unit, and the output and the stored energy absorption power are reduced through a photovoltaic cutting machine so that the delta P is reduced to 0;
in the area network power absorption state, according to an area network absorption power control strategy: if the energy storage SOC is less than 0.1 and delta P bat =0, Δp becomes 0 by cutting out the partial area load; if the energy storage SOC is more than or equal to 0.1 and delta P bat Not less than DeltaP, and discharging through an energy storage unit to enable DeltaP to become 0; if the energy storage SOC is more than or equal to 0.1 and the energy storage adjustable power delta P bat And < [ delta ] P, the [ delta ] P becomes 0 by cutting off the partial area load and discharging the energy storage unit.
Optionally, when the determined power adjustment object is subjected to power adjustment according to the selected control strategy, if the load of the area needs to be removed, the area is removed according to the importance degree of the load.
Optionally, if the power adjustment object is a single type of energy storage unit or photovoltaic unit, the regional power grid power deficiency is equally distributed to each subunit in the energy storage unit or photovoltaic unit;
and each subunit in the energy storage unit and the photovoltaic unit regulates the power output of the energy storage unit and the photovoltaic unit for multiple times in a time-sharing way according to the distributed power regulating quantity until the corresponding power regulating distribution quantity is reached.
Since the energy storage regulation costs are lower than the photovoltaic and load regulation, taking into account the economy of the power regulation and the impact of the power regulation on the individual power supply units and load units, as a preferred embodiment, the power regulation of the determined power regulation object according to the selected control strategy further comprises: determining a power shortage allocation scheme by using a preset power adjustment optimization model, wherein an objective function of the power adjustment optimization model is as follows:
minf(x)＝P 1 ＝P 2 ＝...＝P n ＝(△P-P b ′ at )/n
the optimization constraints include: photovoltaic or load regulating capacity constraints, expressed as: p is more than or equal to 0 l ≤P max ；
The distributed load shedding cycle constraint is expressed as: t is more than or equal to 0 l ≤T max ；
Energy storage adjustable power constraint is expressed as: p is more than or equal to 0 b ′ at ≤△P bat ；
Wherein n represents the number of photovoltaic subunits or load subunits involved in power regulation, P l The power regulation quantity allocated to the first photovoltaic subunit or load subunit involved in power regulation, P b ′ at Represents the energy storage power adjustment quantity, P max Representing the upper power regulating capacity limit, T, of a photovoltaic subunit or a load subunit involved in power regulation l Representing the time between two adjustments of the same load object, T max Representing the most significant of the distributed load shedding cyclesLarge value.
The control thought of the power adjustment optimization model is as follows: when the energy storage has the adjustment capacity, the energy storage adjustment capacity which is as large as possible can be determined on the premise of meeting the energy storage adjustment capacity range and taking the average of the photovoltaic or load adjustment quantity as small as possible, the energy storage adjustment capacity can be selected to be smaller than the maximum value of the energy storage adjustment capacity, the economical thought of energy storage priority adjustment is met, the impact of power adjustment on the photovoltaic or load can be reduced, meanwhile, the adjusted power surplus caused by the system error can be further adjusted through the possible remaining energy storage adjustment capacity after the adjustment of the photovoltaic or load. When the energy storage does not have the regulation capacity, all real-time power shortage is distributed to each photovoltaic subunit or load subunit in average.
In a second aspect, the present invention provides an off-grid control device for a regional power grid, including:
the operation data acquisition module is configured for the real-time electric energy parameter data on the connecting wire, the photovoltaic unit access wire, the energy storage unit access wire and each distribution branch wire;
the power calculation module is configured to calculate real-time power on each corresponding line according to the acquired electric energy parameter data;
the power shortage calculation module is configured to calculate the power shortage of the off-grid regional power grid according to the real-time power on the photovoltaic unit access line, the energy storage unit access line and each distribution branch line when the power of the tie line is 0 and the regional power grid runs off-grid;
and a power regulation control module configured to obtain operation state information of the energy storage unit if the regional power grid power deficiency is not 0, and perform power regulation control on at least one of the photovoltaic unit, the energy storage unit and the regional load according to a preset regional power grid outgoing power control strategy or a regional power grid absorption power control strategy according to a tie-line power direction corresponding to the regional power grid power deficiency and the operation state information of the energy storage unit
In a third aspect, the present invention provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the regional power grid off-grid control method according to the first aspect.
In a fourth aspect, the invention provides a regional power grid system, which comprises a main line, a gas turbine, a photovoltaic unit, an energy storage unit and a distribution branch line, wherein the gas turbine, the photovoltaic unit, the energy storage unit and the distribution branch line are connected with the main line, the main line is connected with a main power grid through a tie switch, the photovoltaic unit and the energy storage unit are respectively connected with the main line through intelligent circuit breakers, and the distribution branch line is connected with a load through the intelligent circuit breakers;
the gas turbine is connected to a main line through a 10.5/110kV transformer; the photovoltaic unit and the energy storage unit are connected to the regional power grid through a two-stage PCS (power conversion system) structure and connected to the main line through a 35/110kV transformer; the distribution branch line is connected with regional load through a 110/20kV or 110/35kV transformer;
the system further comprises a monitoring subsystem for executing the off-grid control method of the regional power grid in the first aspect to control the off-grid regional power grid.
Optionally, the inverter of the photovoltaic unit adopts MPPT-based maximum power point tracking control, and the inverter of the energy storage unit adopts PQ constant power control;
and/or the monitoring subsystem comprises a control module and an acquisition unit, wherein the acquisition unit comprises a voltage sensor and a current sensor which are respectively arranged on a connecting wire, a distribution branch wire, a photovoltaic unit access wire and an energy storage unit access wire; the control module responds to the off-grid of the regional power grid, acquires the electric signals transmitted by the acquisition unit, and executes the off-grid control method of the regional power grid.
Advantageous effects
The regional power grid system and the off-grid control method thereof can maintain stable internal frequency of the system through the coordination control of multiple energy sources after the island effect occurs; in the process of converting from the grid-connected mode to the off-grid mode, the power supply in the system is regulated and controlled, so that the safe and stable control in the system after off-grid is realized, the smooth transition from the grid-connected mode to the off-grid mode is ensured, and the impact on the system caused by off-grid moment is reduced. At present, a large number of regional power grids exist in China, and the implementation of the invention can obviously improve the power supply reliability of the remote regional power grids.
Meanwhile, the invention considers economy, and energy storage in the system is preferentially involved in power adjustment when the regional power grid is unbalanced, so that the cost of off-grid emergency control of the regional power grid is reduced.
Drawings
FIG. 1 is a schematic diagram of a regional power grid system topology of the present invention;
FIG. 2 is a schematic flow chart of the off-grid control method of the regional power grid of the present invention;
FIG. 3 is a schematic diagram illustrating a control logic flow in a power-out-of-grid state according to an embodiment of the present invention;
FIG. 4 is a schematic flow chart of control logic in a power absorption state of a regional power grid according to an embodiment of the present invention;
FIG. 5 is a diagram showing the power balance frequency variation in scenario 1 according to one embodiment of the present invention;
FIG. 6 is a graph showing the frequency change of the power shortage of the regional power grid in scenario 2 according to one embodiment of the present invention;
FIG. 7 is a graph showing the comparison of frequency changes in scene 3 using different cutting modes according to one embodiment of the present invention;
fig. 8 is a graph showing frequency variation versus different energy storage adjustment modes in scene 4 according to an embodiment of the present invention.
Fig. 9 is a comparison diagram of frequency variation of a cutting machine energy storage combination mode in a scene 5 according to an embodiment of the invention.
Detailed Description
Further description is provided below in connection with the drawings and the specific embodiments.
Example 1
The embodiment introduces a regional power grid off-grid control method, and referring to fig. 1, a regional power grid topological structure suitable for the control method comprises a main line, a gas turbine, a photovoltaic unit, an energy storage unit and a distribution branch line, wherein the gas turbine, the photovoltaic unit, the energy storage unit and the distribution branch line are connected with the main line, the main line is connected with the main power grid through a tie-line connecting switch, the photovoltaic unit and the energy storage unit are respectively connected with the main line through intelligent circuit breakers, and the distribution branch line is connected with regional load through the intelligent circuit breakers.
Referring to fig. 2, the regional power grid off-grid control method includes:
acquiring real-time electric energy parameter data on the interconnection line, the photovoltaic unit access line, the energy storage unit access line and each distribution branch line;
calculating real-time power on each corresponding line according to the acquired electric energy parameter data;
when the power of the tie line is 0, the regional power grid runs off the grid, and the power shortage of the regional power grid after off the grid is calculated according to the real-time power on the photovoltaic unit access line, the energy storage unit access line and each distribution branch line;
and if the regional power grid power shortage is not 0, acquiring the running state information of the energy storage unit, and performing power regulation control on at least one of the photovoltaic unit, the energy storage unit and the regional load according to a preset regional power transmission control strategy or a regional power absorption control strategy according to the tie line power direction corresponding to the regional power shortage and the running state information of the energy storage unit.
With reference to fig. 1 to 4, a specific implementation of the off-grid control method in this embodiment includes the following.
1. Electrical energy data acquisition and calculation
The electric energy data acquisition is the basis of regional power grid control, in order to realize off-grid emergency control and control under other states, the method of the embodiment needs to acquire voltage and current data of the connecting lines, the distribution branch lines and the power supply unit buses, and real-time power on each corresponding line can be calculated according to the acquired voltage and current data.
When the main power grid faults or the tie lines are detected to be overhauled, or the main power grid faults or the tie line overhauling notification information sent from the outside is received, the tie lines can be controlled to be disconnected through the tie switch at the moment, so that the regional power grid runs off-grid.
In order to ensure the control reliability, the disconnection delay of the tie line switch is considered, the real-time power of the tie line can be detected and calculated through the real-time sampling of the voltage and the current after the tie line switch is controlled to be disconnected, whether the regional power grid is actually in an off-grid state is judged, when the real-time power of the tie line is 0, the regional power grid enters an off-grid running state, and at the moment, the real-time power shortage of the regional power grid can be calculated according to the real-time power on each line in the regional power grid, and the formula is as follows:
wherein P is hot Is the active power output of the gas turbine, P pv Is the active power output of each photovoltaic subunit, N is the number of the photovoltaic subunits and P bat Is the active power output of each energy storage subunit, M is the number of the energy storage subunits, P load The load units consume the work power, and K is the number of regional load units.
2. Tie line power direction determination
According to the calculated real-time power shortage delta P of the regional power grid, the power direction of the tie line can be judged and obtained:
if the power shortage delta P of the regional power grid is 0, no power exchange is represented on the connecting line, and the regional power grid power adjustment is not needed at the moment
If delta P >0, the power direction of the interconnecting line is the power output direction of the regional power grid, which indicates that the power output of the regional power grid exceeds the power load demand;
if delta P is less than 0, the power direction of the connecting line is the power absorption direction of the regional power grid, and the insufficient power output in the regional power grid is indicated.
The invention establishes different power control strategies aiming at different tie-line power directions, and can select the corresponding power control strategy to carry out corresponding control after determining the tie-line power directions.
3. Energy storage priority concept and power control strategy combination
Compared with photovoltaic and load regulation, the energy storage regulation cost is lower, so that the energy storage control method adopts the idea of energy storage priority when a control strategy is designated, and meanwhile, as the gas turbine is in a constant power running state and has no power in an adjustable power balance area network, the power control object coordinates in an energy storage unit, a photovoltaic unit and an area load.
After the power shortage of the regional power grid is calculated, the embodiment needs to acquire the running state information of the energy storage unit, and then the running state information of the energy storage unit determines a control object and a control measure in a real-time power direction state, which is specifically as follows.
3.1 under the regional power grid power delivery state, the regional power grid power output exceeds the power load demand, and the gas turbine has no adjustable power, so that the energy storage working state needs to be adjusted to absorb redundant power or cut off part of the photovoltaic unit, and the power output and the load in the regional power grid meet the balance state.
According to the area network outgoing power control strategy:
if the energy storage SOC is more than 0.9 and delta P bat The method comprises the following steps that (1) energy storage cannot participate in power regulation, only a cutting measure can be adopted, a power regulation object is a photovoltaic unit, power shortage is distributed to all photovoltaic subunits, and the output is reduced by cutting the photovoltaic subunits so that DeltaP is reduced to 0;
if the energy storage SOC is less than or equal to 0.9 and delta P bat Not less than DeltaP, taking economy into consideration, the power regulation object is an energy storage unit, the power shortage is distributed to all energy storage subunits, and the DeltaP is reduced to 0 by the power absorption of the energy storage subunits;
if the energy storage SOC is less than or equal to 0.9 and the energy storage adjustable power delta P bat And if the power adjustment object is a photovoltaic unit and an energy storage unit, distributing the power shortage to the photovoltaic units and the energy storage unit, and reducing the output and the stored energy to absorb the power through a photovoltaic cutter so as to reduce the delta P to 0. In order to realize accurate control, part of the photovoltaic unit can be cut off first, and surplus power shortage is corrected by energy storage.
In order to reduce the impact of control measures on the regional power grid, the adjustment of the photovoltaic cutting machine or the energy storage subunit adopts a time-sequence adjustment mode, and is divided into a plurality of times (such as t 1 、t 2 、t 3 Three times) performs the corresponding power adjustment actions until the allocated power adjustment amount is reached. Reference is made to the comparison shown in figures 5 to 8The idea of time-sharing sequence adjustment can further realize smooth transition of the operation state of the regional power grid at the off-grid moment.
3.2 under the power absorption state of the regional power grid, the power output in the regional power grid is insufficient, and the gas turbine has no adjustable power, so that the power of an energy storage output balance system is required to be adjusted or a part of unimportant load is cut off, and the power output and the load in the regional power grid can meet the balance state.
According to the area network absorption power control strategy:
if the energy storage SOC is less than 0.1 and the energy storage adjustable power delta P bat If the energy storage is=0, the energy storage cannot participate in power regulation, the power regulation object is a regional load, and the delta P is changed into 0 by cutting off the regional load; if partial regional load is required, considering the importance degree of the load, firstly cutting off unimportant load in the regional power grid, and cutting off the load units can also adopt a time sequence (t 1 、t 2 、t 3 ) A mode of action excision;
if the energy storage SOC is more than or equal to 0.1 and the energy storage adjustable power delta P bat More than or equal to DeltaP, the energy storage regulation capacity is enough, the power regulation object is an energy storage unit, and DeltaP is changed into 0 through the discharge of the energy storage unit; the energy storage subunit can also adopt a time-sharing sequence adjustment mode;
if the energy storage SOC is more than or equal to 0.1 and the energy storage adjustable power delta P bat And (3) the power regulation object is an energy storage unit and a regional load, and the delta P is changed to 0 by cutting off part of the regional load and discharging the energy storage unit. Furthermore, after partial load is cut off, surplus power adjustment quantity can be corrected by energy storage, so that the aim of accurate control is achieved.
In the embodiment, if the power regulation object is a single energy storage unit or a photovoltaic unit, the power shortage of the regional power grid is equally distributed to all the sub-units in the energy storage unit or the photovoltaic unit.
If the stability of each power supply unit or load unit and the economy of power regulation are considered at the same time, the power shortage distribution scheme can be determined by utilizing a preset power regulation optimization model, and the objective function of the power regulation optimization model is as follows:
minf(x)＝P 1 ＝P 2 ＝...＝P n ＝(△P-P b ′ at )/n
the optimization constraints include: photovoltaic or load regulating capacity constraints, expressed as: p is more than or equal to 0 l ≤P max ；
The distributed load shedding cycle constraint is expressed as: t is more than or equal to 0 l ≤T max ；
Energy storage adjustable power constraint is expressed as: p is more than or equal to 0 b ′ at ≤△P bat ；
Wherein n represents the number of photovoltaic subunits or load subunits involved in power regulation, P l The power regulation quantity allocated to the first photovoltaic subunit or load subunit involved in power regulation, P b ′ at Represents the energy storage power adjustment quantity, P max Representing the upper power regulating capacity limit, T, of a photovoltaic subunit or a load subunit involved in power regulation l Representing the time between two adjustments of the same load object, T max Representing the maximum value of the distributed load shedding period.
The control thought of the power adjustment optimization model is as follows: when the energy storage has the adjustment capacity, the energy storage adjustment capacity which is as large as possible can be determined on the premise of meeting the energy storage adjustment capacity range and taking the average of the photovoltaic or load adjustment quantity as small as possible, the energy storage adjustment capacity can be selected to be smaller than the maximum value of the energy storage adjustment capacity, the economical thought of energy storage priority adjustment is met, the impact of power adjustment on the photovoltaic or load can be reduced, meanwhile, the surplus of the adjusted power deficiency caused by the system error can be further adjusted through the possible surplus of the energy storage adjustment capacity after the adjustment of the photovoltaic or load. When the energy storage does not have the regulation capacity, all real-time power shortage is distributed to each photovoltaic subunit or load subunit in average.
The present embodiment is described below with an application example: the regional power grid comprises 1 gas turbine with the capacity of 40MW, and the voltage and the frequency of the regional power grid are maintained constant through the gas turbine after the regional power grid is off-grid; the capacity of the photovoltaic single machine is 500kW, each photovoltaic unit is connected into a power grid through an inverter, the total capacity is 12MW, and the inverter adopts MPPT maximum power point tracking control; the single-machine capacity of the energy storage battery is 500KW, each energy storage unit is connected to a power grid through an inverter, the total capacity is 12MW, and the inverter is controlled by adopting constant-power PQ.
When the regional gas turbine operates in a constant power mode, and the photovoltaic is tracked and controlled at a maximum power point, the regional electric energy firstly meets the requirements of regional loads, the redundant electric energy is firstly absorbed by the energy storage, and when the energy storage SOC is more than 0.9 or the power absorbed by the energy storage is maximum, the rest power is sent out to a main power grid; or when the regional power supply output does not meet the local load requirement, the main power grid bears redundant electric energy, and the interconnecting wire transmits the electric energy to the regional power grid. When the off-grid switching is caused by the fault of the connecting line and the island operation mode is entered, in order to facilitate analysis, simulation research is carried out on the influence of the fault of the connecting line on the off-grid transient process and the operation condition of the regional power grid after the off-grid switching under the following scenes, and different control measures are adopted under different scenes to obtain a frequency change curve of the regional power grid after the off-grid.
Scene 1: the local power supply output meets the load requirement of the area, and no control measures are needed when no power exchange is carried out on the connecting lines;
scene 2: under the condition of the power transmission of the regional power grid, no control measures are taken;
scene 3: under the condition of power transmission of the regional power grid, the energy storage is in the full charge condition or the SOC is more than or equal to 0.9, the energy storage can not provide power support, and only a cutting measure can be adopted;
scene 4: under the condition of the power delivered by the regional power grid, energy storage adjustable power delta P bat When the delta Pt is not less than and the SOC is less than 0.9, adopting an energy storage adjustment measure;
scene 5: under the condition of the power delivered by the regional power grid, energy storage adjustable power delta P bat Adopting a measure of combining energy storage regulation and cutting machine, and trimming the machine quantity by the energy storage;
as can be seen from fig. 5, when the power balance is satisfied inside the regional power grid, the regional power grid frequency remains stable after 4s dynamic change without any measures; as can be seen from fig. 6, when there is a power exchange on the tie-line, the regional grid is off-grid, and no measures are taken, eventually the grid frequency will collapse.
When the regional power grid is used for sending power, different control measures are adopted according to the power supply condition, energy storage cannot participate in power regulation in the regional power grid under the condition of scene 3, only a cutting measure can be adopted, as shown in fig. 6, the frequency peak generated by a photovoltaic unit is cut off at the same time to reach 0.2Hz, and the time-sharing cutting machine only generates a peak of 0.1 Hz; scenario 4 when there is sufficient adjustable power stored in the regional power grid, as shown in fig. 7, by taking different measures of energy storage adjustment, the corresponding power is adjusted by the energy storage at the same time according to the regional power shortage of the regional power grid, a frequency spike of 0.075Hz is generated, and the corresponding power is adjusted by time-sharing energy storage, so that a frequency spike of 0.05Hz is generated.
When the energy storage in the regional power grid has adjustable power but does not meet the power shortage, the energy storage and the cutting machine are combined according to the scene 5, as shown in fig. 8, part of the energy storage power is adjusted in a time-sharing mode, part of the photovoltaic units are cut off, and meanwhile, the energy storage can correct over-cutting or under-cutting caused by inaccurate cutting machine, so that impact on the regional power grid caused by off-grid moment is alleviated.
Example 2
The embodiment describes a regional power grid system, based on the system architecture described in embodiment 1, in which the gas turbine is connected to the main line via a 10.5/110kV transformer; the photovoltaic unit and the energy storage unit are connected to the regional power grid through a two-stage PCS (power conversion system) structure and connected to the main line through a 35/110kV transformer; the distribution branch line is connected with regional load through a 110/20kV or 110/35kV transformer.
The gas turbine is used as a main power supply of the regional power grid, constant power control is adopted, and the voltage and the frequency in the regional power grid are maintained stable; the photovoltaic unit comprises photovoltaic subunits, and an inverter of the photovoltaic subunits adopts MPPT-based maximum power point tracking control; the energy storage unit comprises energy storage subunits, the energy storage inverter is controlled by constant power, and meanwhile, the energy storage subunits are provided with an SOC monitoring system which can monitor charge and discharge data and an SOC state curve of the energy storage battery, and when the state of the energy storage SOC is SOC less than 0.1 or SOC more than 0.9, the energy storage unit is automatically controlled to stop charge and discharge.
The regional power grid system also comprises a monitoring subsystem, wherein the monitoring subsystem comprises a control module and an acquisition unit, and the acquisition unit comprises a voltage sensor and a current sensor which are respectively arranged on the connecting wire, the distribution branch wire, the photovoltaic unit access wire and the energy storage unit access wire; the control module is in communication connection with the dispatching center and is used for receiving information related to dispatching, such as information of main power grid faults or overhauls and the like. The control module may control the on-off state of the tie switch according to the received information, control the off-grid or grid connection of the regional power grid, and respond to the off-grid of the regional power grid, obtain the electrical signal transmitted by the acquisition unit, and execute the off-grid control method of the regional power grid described in embodiment 1 to control the off-grid regional power grid, and during the control period, the control module controls the photovoltaic unit, the energy storage unit and the access or the cutting off of the regional load through the intelligent circuit breaker.
Example 3
The present embodiment introduces a regional power grid off-grid control device based on the same inventive concept as embodiment 1, which includes:
the operation data acquisition module is configured for the real-time electric energy parameter data on the connecting wire, the photovoltaic unit access wire, the energy storage unit access wire and each distribution branch wire;
the power calculation module is configured to calculate real-time power on each corresponding line according to the acquired electric energy parameter data;
the power shortage calculation module is configured to calculate the power shortage of the off-grid regional power grid according to the real-time power on the photovoltaic unit access line, the energy storage unit access line and each distribution branch line when the power of the tie line is 0 and the regional power grid runs off-grid;
and the power regulation control module is configured to acquire the operation state information of the energy storage unit if the regional power grid power shortage is not 0, and perform power regulation control on at least one of the photovoltaic unit, the energy storage unit and the regional load according to a preset regional power grid outgoing power control strategy or a regional power grid absorption power control strategy according to the tie line power direction corresponding to the regional power grid power shortage and the operation state information of the energy storage unit.
The specific implementation of each functional module described above is referred to the relevant content of embodiment 1 and will not be repeated.
Example 4
The present embodiment describes a computer-readable storage medium on which a computer program is stored which, when executed by a processor, implements the regional power grid off-grid control method described in embodiment 1.
In summary, the embodiment of the invention can realize safe and stable control in the system after grid-off through regulating and controlling the power supply in the system in the process of converting the regional power grid from the grid-connected mode to the off-grid mode, ensure smooth transition from the grid-connected mode to the off-grid mode, reduce impact on the system caused by the off-grid moment, reduce the regulating and controlling cost by a power regulating strategy with energy storage priority, and provide technical support for stable off-grid operation of the regional power grid while improving the reliability of the power grid aiming at the island power grid with more renewable energy installation occupation at the tail end of the power grid and weaker connection with the large power grid.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the claims, which are all within the protection of the present invention.
Claims (13)
1. The regional power grid off-grid control method comprises a main line, a gas turbine, a photovoltaic unit, an energy storage unit and a distribution branch line, wherein the gas turbine, the photovoltaic unit, the energy storage unit and the distribution branch line are connected with the main line, the main line is connected with the main power grid through a tie-line tie switch, the photovoltaic unit and the energy storage unit are respectively connected with the main line through intelligent circuit breakers, and the distribution branch line is connected with regional loads through the intelligent circuit breakers; the control method is characterized by comprising the following steps:
acquiring real-time electric energy parameter data on the interconnection line, the photovoltaic unit access line, the energy storage unit access line and each distribution branch line;
calculating real-time power on each corresponding line according to the acquired electric energy parameter data;
when the power of the tie line is 0, the regional power grid runs off the grid, and the power shortage of the regional power grid after off the grid is calculated according to the real-time power on the photovoltaic unit access line, the energy storage unit access line and each distribution branch line;
and if the regional power grid power shortage is not 0, acquiring the running state information of the energy storage unit, and performing power regulation control on at least one of the photovoltaic unit, the energy storage unit and the regional load according to a preset regional power transmission control strategy or a regional power absorption control strategy according to the tie line power direction corresponding to the regional power shortage and the running state information of the energy storage unit.
2. The regional power grid off-grid control method of claim 1, further comprising: and receiving the external main power grid fault overhaul notification information, and controlling the disconnection of the tie switch in response to the information so that the tie line power is 0 and the regional power grid operates off-grid.
3. The method for off-grid control of a regional power grid according to claim 1, wherein the formula is as follows, wherein the off-grid regional power shortage is calculated according to real-time power on the photovoltaic unit access line, the energy storage unit access line and each distribution branch line:
wherein P is hot Is the active power output of the gas turbine, P pv Is the active power output of each photovoltaic subunit,n is the number of photovoltaic subunits, P bat Is the active power output of each energy storage subunit, M is the number of the energy storage subunits, P load The load units consume the work power, and K is the number of regional load units.
4. The regional power grid off-grid control method according to claim 1, wherein the performing power adjustment control on at least one of the photovoltaic unit, the energy storage unit and the regional load according to a preset regional power transmission control strategy or a regional power absorption control strategy according to the tie power direction corresponding to the regional power shortage and the energy storage unit operation state information comprises:
judging the power direction of the connecting line according to the power shortage of the regional power grid, wherein if delta P is more than 0, the power direction of the connecting line is the power transmission direction of the regional power grid, and if delta P is less than 0, the power direction of the connecting line is the power absorption direction of the regional power grid;
selecting a control strategy as a corresponding area network outgoing power control strategy or an area network absorption power control strategy according to the judging result of the tie line power direction;
determining an object participating in power regulation in a control strategy according to the running state information of the energy storage unit;
and carrying out power regulation on the determined power regulation object according to the selected control strategy so that the power shortage delta P of the regional power grid after the power regulation is 0.
5. The regional power grid off-grid control method according to claim 4, wherein the determining the object participating in power adjustment in the control strategy according to the energy storage unit operation state information comprises:
a) In the area network outgoing power control strategy: if the energy storage SOC is more than 0.9 and the energy storage adjustable power delta P bat =0, then the power conditioning object is a photovoltaic unit; if the energy storage SOC is less than or equal to 0.9 and the energy storage adjustable power delta P bat More than or equal to delta P, the power regulation object is an energy storage unit; if the energy storage SOC is less than or equal to 0.9 and the energy storage adjustable power delta P bat The power regulation object is a photovoltaic unit and an energy storage unit;
b) In the area network absorption power control strategy: if the energy storage SOC is less than 0.1 and the energy storage adjustable power delta P bat =0, then the power adjustment object is the zone load; if the energy storage SOC is more than or equal to 0.1 and the energy storage adjustable power delta P bat More than or equal to delta P, the power regulation object is an energy storage unit; if the energy storage SOC is more than or equal to 0.1 and the energy storage adjustable power delta P bat And < delta P, the power regulation object is an energy storage unit and a regional load.
6. The regional power grid off-grid control method according to claim 5, wherein performing power adjustment on the determined power adjustment object according to the selected control strategy so that the power-adjusted regional power shortage Δp is 0, comprises:
in the area network power delivery state, according to an area network delivery power control strategy: if the energy storage SOC is more than 0.9 and delta P bat =0, then the power deficit is distributed to each photovoltaic subunit, and the output is reduced by the photovoltaic subunit cutting machine so that Δp is reduced to 0; if the energy storage SOC is less than or equal to 0.9 and delta P bat More than or equal to DeltaP, distributing the power shortage to each energy storage subunit, and reducing DeltaP to 0 by absorbing power by the energy storage subunits; if the energy storage SOC is less than or equal to 0.9 and the energy storage adjustable power delta P bat Less than delta P, distributing the power shortage to each photovoltaic unit and the energy storage unit, and reducing the output and the stored energy absorption power to enable delta P to be reduced to 0 through the photovoltaic cutting machine;
in the area network power absorption state, according to an area network absorption power control strategy: if the energy storage SOC is less than 0.1 and delta P bat =0, Δp becomes 0 by cutting out the partial area load; if the energy storage SOC is more than or equal to 0.1 and delta P bat Not less than deltaP, and discharging through the energy storage unit to enable deltaP to become 0; if the energy storage SOC is more than or equal to 0.1 and the energy storage adjustable power delta P bat By cutting off the partial area load and discharging the energy storage unit, Δp becomes 0.
7. The regional power grid off-grid control method according to claim 6, wherein when the determined power adjustment object is subjected to power adjustment according to the selected control strategy, if regional loads need to be removed, the removal is performed according to the importance degree of the loads.
8. The regional power grid off-grid control method according to claim 6, wherein if the power adjustment object is a single type of energy storage unit or photovoltaic unit, the regional power grid power deficiency is equally distributed to each subunit in the energy storage unit or photovoltaic unit;
and each subunit in the energy storage unit and the photovoltaic unit regulates the power output of the energy storage unit and the photovoltaic unit for multiple times in a time-sharing way according to the distributed power regulating quantity until the corresponding power regulating distribution quantity is reached.
9. The regional power grid off-grid control method of claim 6, wherein the power adjusting the determined power adjustment object according to the selected control strategy further comprises: determining a power shortage allocation scheme by using a preset power adjustment optimization model, wherein an objective function of the power adjustment optimization model is as follows:
minf(x)＝P 1 ＝P 2 ＝...＝P n ＝(ΔP-P b ′ at )/n
the optimization constraints include: photovoltaic or load regulating capacity constraints, expressed as: p is more than or equal to 0 l ≤P max ；
The distributed load shedding cycle constraint is expressed as: t is more than or equal to 0 l ≤T max ；
Energy storage adjustable power constraint is expressed as: p is more than or equal to 0 b ′ at ≤ΔP bat ；；
Wherein n represents the number of photovoltaic subunits or load subunits involved in power regulation, P l The power regulation quantity delta P distributed by the first photovoltaic subunit or the load subunit participating in power regulation b ′ at Represents the energy storage power adjustment quantity, P max Representing the upper power regulating capacity limit, T, of a photovoltaic subunit or a load subunit involved in power regulation l Representing the time between two adjustments of the same load object, T max Representing the maximum value of the distributed load shedding period.
10. An off-grid control device for a regional power grid, which is characterized by comprising:
the operation data acquisition module is configured for the real-time electric energy parameter data on the connecting wire, the photovoltaic unit access wire, the energy storage unit access wire and each distribution branch wire;
the power calculation module is configured to calculate real-time power on each corresponding line according to the acquired electric energy parameter data;
the power shortage calculation module is configured to calculate the power shortage of the off-grid regional power grid according to the real-time power on the photovoltaic unit access line, the energy storage unit access line and each distribution branch line when the power of the tie line is 0 and the regional power grid runs off-grid;
and the power regulation control module is configured to acquire the operation state information of the energy storage unit if the regional power grid power shortage is not 0, and perform power regulation control on at least one of the photovoltaic unit, the energy storage unit and the regional load according to a preset regional power grid outgoing power control strategy or a regional power grid absorption power control strategy according to the tie line power direction corresponding to the regional power grid power shortage and the operation state information of the energy storage unit.
11. A computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements a regional power grid off-grid control method as claimed in any one of claims 1 to 9.
12. The regional power grid system is characterized by comprising a main line, a gas turbine, a photovoltaic unit, an energy storage unit and a distribution branch line, wherein the gas turbine, the photovoltaic unit, the energy storage unit and the distribution branch line are connected with the main line, the main line is connected with a main power grid through a tie switch, the photovoltaic unit and the energy storage unit are respectively connected with the main line through intelligent circuit breakers, and the distribution branch line is connected with a load through the intelligent circuit breakers;
the gas turbine is connected to a main line through a 10.5/110kV transformer; the photovoltaic unit and the energy storage unit are connected to the regional power grid through the two-stage PCS structure and connected to the main line through the 35/110kV transformer; the distribution branch line is connected with regional load through a 110/20kV or 110/35kV transformer;
further comprising a monitoring subsystem for performing the off-grid control method of any one of claims 1-9 for controlling an off-grid regional power grid.
13. The regional power grid system of claim 12, wherein the inverter of the photovoltaic unit employs MPPT-based maximum power point tracking control and the inverter of the energy storage unit employs PQ constant power control;
and/or the monitoring subsystem comprises a control module and an acquisition unit, wherein the acquisition unit comprises a voltage sensor and a current sensor which are respectively arranged on a connecting wire, a distribution branch wire, a photovoltaic unit access wire and an energy storage unit access wire; the control module responds to the off-grid of the regional power grid, acquires the electric signals transmitted by the acquisition unit, and executes the off-grid control method of the regional power grid.
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