CN117639081B - Photovoltaic energy storage inversion parallel operation system and photovoltaic energy scheduling method thereof - Google Patents
Photovoltaic energy storage inversion parallel operation system and photovoltaic energy scheduling method thereof Download PDFInfo
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- CN117639081B CN117639081B CN202410093438.2A CN202410093438A CN117639081B CN 117639081 B CN117639081 B CN 117639081B CN 202410093438 A CN202410093438 A CN 202410093438A CN 117639081 B CN117639081 B CN 117639081B
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- 238000004146 energy storage Methods 0.000 title claims abstract description 158
- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000007599 discharging Methods 0.000 claims description 16
- 230000009467 reduction Effects 0.000 claims description 2
- 238000010248 power generation Methods 0.000 abstract description 7
- 230000005611 electricity Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000000087 stabilizing effect Effects 0.000 description 3
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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
- H02J3/38—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
- H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
- H02J3/0075—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources for providing alternative feeding paths between load and source according to economic or energy efficiency considerations, e.g. economic dispatch
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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
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
- H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
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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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention discloses a photovoltaic energy storage inversion parallel operation system and a photovoltaic energy scheduling method thereof, wherein the photovoltaic energy scheduling method comprises the following steps: the method comprises the steps of respectively obtaining the maximum allowed feed power and the maximum allowed charging power of each photovoltaic energy storage inversion parallel operation system in the photovoltaic energy storage inversion parallel operation system, and obtaining the maximum allowed feed power and the maximum allowed charging power of the photovoltaic energy storage inversion parallel operation system according to the maximum allowed feed power and the maximum allowed charging power; and acquiring the total power of the load, and carrying out energy scheduling according to the total power of the load and the maximum allowable feed power and the maximum allowable charging power of the photovoltaic energy storage inversion parallel operation system. The invention avoids the influence of unstable photovoltaic power generation on the power grid port, and the feed power is stable.
Description
Technical Field
The invention relates to the technical field of energy storage systems, in particular to a photovoltaic energy storage inversion parallel operation system and a photovoltaic energy scheduling method thereof.
Background
With the popularization of renewable energy sources and the development of the electric power market, the photovoltaic grid-connected energy storage system is also synchronously developed, and the electricity generated by the photovoltaic can be sold to a power grid, the energy storage system can be charged, and the energy storage system can take electricity from the power grid and sell the stored electricity to the power grid.
In the parallel operation system composed of a plurality of photovoltaic energy storage inversion single machine systems, when the battery unit SOC of one single machine system is full, the redundant PV energy of the single machine system is always fed to a power grid, and the battery units of other single machine systems still have insufficient electric quantity, so that the income of users is always damaged. In addition, when the PV changes severely, the power fed from the grid side also changes severely, which is not very friendly to the weak grid environment, and at the same time, if the AC side is not regulated timely, the battery unit may be discharged with power exceeding the limit value in a short time, and damage is caused to the battery unit.
The foregoing background is only for the purpose of facilitating an understanding of the principles and concepts of the application and is not necessarily in the prior art to the present application and is not intended to be used as an admission that such background is not entitled to antedate such novelty and creativity by virtue of prior application or that it is already disclosed at the date of filing of this application.
Disclosure of Invention
In order to solve the technical problems, the invention provides a photovoltaic energy storage inversion parallel operation system and a photovoltaic energy scheduling method thereof, which avoid the influence of unstable photovoltaic power generation on a power grid port and stabilize feed power.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect, the invention discloses a photovoltaic energy scheduling method of a photovoltaic energy storage inversion parallel operation system, which comprises the following steps:
s1: the method comprises the steps of respectively obtaining maximum allowed feed power and maximum allowed charging power of each photovoltaic energy storage inversion single machine system in a photovoltaic energy storage inversion parallel machine system, and obtaining the maximum allowed feed power and the maximum allowed charging power of the photovoltaic energy storage inversion parallel machine system according to the maximum allowed feed power and the maximum allowed charging power of each photovoltaic energy storage inversion single machine system;
S2: and acquiring the total power of the load, and carrying out energy scheduling according to the total power of the load and the maximum allowable feed power and the maximum allowable charging power of the photovoltaic energy storage inversion parallel operation system.
Preferably, step S1 specifically includes:
S11: respectively acquiring a charging and discharging power limit value of a battery unit and a charging and discharging power limit value of an inverter in each photovoltaic energy storage inversion single machine system;
s12: according to the charging and discharging power limit value of the battery unit and the charging and discharging power limit value of the inverter in each photovoltaic energy storage inversion single machine system obtained in the step S11, combining the current state of each photovoltaic energy storage inversion single machine system, and determining the maximum allowable feed power and the maximum allowable charging power of each photovoltaic energy storage inversion single machine system;
S13: adding the maximum allowable feed power of all the photovoltaic energy storage inversion single machine systems to obtain the maximum allowable feed power of the photovoltaic energy storage inversion parallel machine system; and adding the maximum allowable charging power of all the photovoltaic energy storage inversion single machine systems to obtain the maximum allowable charging power of the photovoltaic energy storage inversion parallel machine system.
Preferably, step S12 further includes: and determining the current state of each photovoltaic energy storage inversion single machine system according to the preset threshold range of the battery unit and the current SOC value of the battery unit of each photovoltaic energy storage inversion single machine system, wherein the preset threshold range of the battery unit is larger than or equal to a first threshold and smaller than or equal to a second threshold.
Preferably, when the current SOC value of the battery unit of the photovoltaic energy storage inversion single machine system is smaller than the first threshold value, the photovoltaic energy storage inversion single machine system is marked as a first marking state; when the current SOC value of the battery unit of the photovoltaic energy storage inversion single machine system is larger than the second threshold value, marking the photovoltaic energy storage inversion single machine system as a second marking state; if the SOC of the battery unit is within a preset threshold value range when the photovoltaic energy storage inversion single machine system is started, marking the photovoltaic energy storage inversion single machine system as a third marking state; if the SOC of the battery unit enters the preset threshold range from the non-preset threshold range after the photovoltaic energy storage inversion single machine system is started, marking the state marked by the photovoltaic energy storage inversion single machine system before entering the preset threshold range as the state of the photovoltaic energy storage inversion single machine system when the SOC of the battery unit is within the preset threshold range.
Preferably, when the photovoltaic energy storage inverter single machine system is marked as a first marked state, the maximum allowable feed power value of the photovoltaic energy storage inverter single machine system is 0, and the maximum allowable charging power value is the smaller of the charging power limit value of the battery unit and the charging power limit value of the inverter; when the photovoltaic energy storage inversion single machine system is marked as a second marked state, the maximum allowable feed power value of the photovoltaic energy storage inversion single machine system is smaller than the discharge power limit value of the battery unit and the discharge power limit value of the inverter, and the maximum allowable charge power value is 0; when the photovoltaic energy storage inversion single machine system is marked as a third marking state, the maximum allowable feed power of the photovoltaic energy storage inversion single machine system is 0, and the maximum allowable charging power is 0.
Preferably, the range of the first threshold value is 80% -90%, and the range of the second threshold value is 91% -99%.
Preferably, step S2 specifically includes:
S21: acquiring the total power of the load, judging whether the maximum allowable feed power of the photovoltaic energy storage inversion parallel operation system is larger than the total power of the load, if so, executing the step S22, and if not, executing the step S25;
S22: calculating first residual power, wherein the first residual power is equal to the total power of the maximum allowable feed power of the photovoltaic energy storage inversion parallel operation system and the load is reduced, judging whether the first residual power is larger than the maximum allowable charging power of the photovoltaic energy storage inversion parallel operation system, if so, executing step S23, and if not, executing step S24;
S23: calculating second residual power, wherein the second residual power is equal to the maximum allowable charging power of the first residual power dimming photovoltaic energy storage inversion parallel operation system, and feeding the second residual power into a power grid;
s24: picking out the photovoltaic energy storage inversion single machine system with the maximum allowable charging power not equal to 0, and distributing the first residual power according to a first preset rule;
S25: and supplying the maximum allowable feed power of the photovoltaic energy storage inversion parallel system to the load, calculating the supplementary electric power, wherein the supplementary electric power is equal to the maximum allowable feed power of the total power reduction photovoltaic energy storage inversion parallel system of the load, and distributing the supplementary electric power according to a second preset rule.
Preferably, the allocation according to the first preset rule means: and distributing the serial numbers of the selected photovoltaic energy storage inversion single machine systems from small to large or from large to small, or distributing the maximum allowable charging power of the selected photovoltaic energy storage inversion single machine systems from small to large or from large to small.
Preferably, the allocation according to the second preset rule means: and picking out the photovoltaic energy storage inversion single machine system with the maximum allowable feed power not equal to 0 according to the sequence of the serial numbers of the photovoltaic energy storage inversion single machine system from small to large or from large to small, and sequentially distributing the feed power of the selected photovoltaic energy storage inversion single machine system according to the sequence of the serial numbers of the photovoltaic energy storage inversion single machine system from small to large or from large to small, wherein the feed power of the photovoltaic energy storage inversion single machine system takes the value as the smaller of the discharge power limit value of a battery unit and the discharge power limit value of an inverter.
In a second aspect, the invention discloses a photovoltaic energy storage inversion parallel machine system, which comprises a plurality of photovoltaic energy storage inversion single machine systems, wherein each photovoltaic energy storage inversion single machine system comprises a photovoltaic, an inverter and a battery unit, each inverter is connected with the corresponding photovoltaic and battery unit, the alternating current sides of the inverters are connected in parallel and connected with a load and a power grid, and the photovoltaic energy storage inversion parallel machine system adopts the photovoltaic energy scheduling method of the first aspect to perform photovoltaic energy scheduling.
Compared with the prior art, the invention has the beneficial effects that: according to the photovoltaic energy storage inversion parallel operation system and the photovoltaic energy scheduling method thereof, the photovoltaic and the energy storage power supply are regarded as a whole, the photovoltaic energy is regarded as all flowing to the energy storage power supply, the energy storage power supply is anchored, the alternating current side of the inverter is used as a unified inlet and outlet of the energy, decoupling of photovoltaic power generation and a power grid port is achieved, the power grid port is not affected by instability of photovoltaic power generation completely, meanwhile, the scheduling of the energy can be achieved only by acquiring the maximum allowable feed power and the maximum allowable charging power, and the PV feed strategy is simplified.
In a further scheme, the maximum allowable feed power and the maximum allowable charging power of the photovoltaic energy storage inversion parallel operation system fully consider the SOC variation of the battery unit, and keep the SOC of each single machine system within a preset threshold range to the greatest extent, so that the effect of stabilizing the feed power of the AC side is further achieved.
Drawings
FIG. 1 is a photovoltaic energy storage inverter parallel machine system disclosed in a preferred embodiment of the present invention;
FIG. 2 is a flow chart of a photovoltaic energy scheduling method disclosed in a preferred embodiment of the present invention;
FIG. 3 illustrates a state of a single machine system determined under a battery cell condition according to an embodiment of the present invention;
FIG. 4 illustrates a determination of the state of a stand-alone system during operation of another battery cell according to an embodiment of the present invention.
Detailed Description
The following describes embodiments of the present invention in detail. It should be emphasized that the following description is merely exemplary in nature and is in no way intended to limit the scope of the invention or its applications.
It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element. In addition, the connection may be for both the fixing action and the circuit/signal communication action.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience in describing embodiments of the invention and to simplify the description by referring to the figures, rather than to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless explicitly defined otherwise.
The terms involved in the present invention will be explained correspondingly in the following.
Photovoltaic energy: i.e. electrical energy after conversion of solar energy.
Maximum allowable feed power: refers to the power that can be used to feed the grid or to supplement other stand-alone systems with power after a condition is met.
As shown in fig. 1, the photovoltaic energy storage inversion parallel operation system of the present invention includes N photovoltaic energy storage inversion single machine systems 11, 12, … …, 1N, each of which includes a PV, an inverter (specifically may be a bidirectional inverter), and a battery unit, for example, the photovoltaic energy storage inversion single machine system 11 includes a PV 111, an inverter 112, and a battery unit 113, the photovoltaic energy storage inversion single machine system 12 includes a PV 121, an inverter 122, and a battery unit 123, and the photovoltaic energy storage inversion single machine system 1N includes a PV 1N1, an inverter 1N2, and a battery unit 1N3; wherein each inverter is connected with a corresponding PV and battery unit respectively; the ac sides of the N inverters are connected in parallel and connected to the load 20 and the grid 30. The photovoltaic energy storage inversion parallel operation system adopts the photovoltaic energy scheduling method in the following preferred embodiment to perform photovoltaic energy scheduling.
When n=1, only one set of photovoltaic energy storage inversion single machine system is arranged in the photovoltaic energy storage inversion parallel machine system. When N is more than 1, a plurality of photovoltaic energy storage inversion single machine systems are arranged in the photovoltaic energy storage inversion parallel machine system, and the photovoltaic energy storage inversion parallel machine systems are formed together. One of the photovoltaic energy storage single-machine systems is a main system, and an inverter thereof is a main inverter (for example, the photovoltaic energy storage single-machine system 11 in fig. 1 is a main system, and the inverter 112 is a main inverter); the remaining photovoltaic energy storage inverter single-machine systems are slave systems, the inverters of which are slave inverters (e.g., photovoltaic energy storage inverter single-machine systems 12, … …, 1N in fig. 1 are slave systems, and inverters 122, … …, 1N2 are slave inverters); each inverter communicates with a respective battery cell and each inverter communicates with each other, and the main inverter 112 communicates with the electricity meter of the grid 30.
As shown in fig. 2, the control method of the photovoltaic energy storage inversion parallel operation system disclosed by the preferred embodiment of the invention comprises the following steps:
S1: the method comprises the steps of respectively obtaining maximum allowed feed power and maximum allowed charging power of each photovoltaic energy storage inversion single machine system in the photovoltaic energy storage inversion parallel machine system, and obtaining the maximum allowed feed power and the maximum allowed charging power of the photovoltaic energy storage inversion parallel machine system according to the maximum allowed feed power and the maximum allowed charging power of each photovoltaic energy storage inversion single machine system;
Each photovoltaic energy storage inversion single machine system comprises a photovoltaic, an inverter and a battery unit, wherein each inverter is connected with the corresponding photovoltaic and battery unit respectively, the alternating current sides of the inverters are connected in parallel and connected with a load and a power grid;
the maximum allowable feed power and the maximum allowable charging power are respectively acquired for each single machine system, and the step S1 specifically comprises the following steps:
S11: respectively acquiring a charging and discharging power limit value of a battery unit and a charging and discharging power limit value of an inverter in each photovoltaic energy storage inversion single machine system;
for each single system, each inverter collects the charging and discharging power limit value of the corresponding battery unit and the charging and discharging power limit value of the inverter.
After the system is operated, the limit value of the charge and discharge power of the battery unit can be dynamically changed according to the SOC value of the battery unit. The battery cell charge-discharge power limit overall presentation is characterized by: the higher the remaining power of the battery unit, especially when approaching a full charge state, the smaller the charging power limit value of the battery unit; the lower the remaining charge of the battery cell, especially when approaching a dump state, the lower the discharge power limit of the battery cell. For example, current soc=96%, charge power limit=1000w, discharge power limit=6000W; as another example, current soc=10%, charge power limit=6000W, and discharge power limit=1000W.
The limit value of the charging and discharging power of the inverter is determined according to the hardware condition, the environmental condition and the like, and the limit value of the charging and discharging power of the inverter is equal to the rated input and output power of the inverter under the condition of excluding other factors. The rated input power and the rated output power of the inverter are determined according to actual conditions; for some inverters, their rated input power = rated output power; for some inverters, their rated input power is not equal to the rated output power.
S12: according to the charge and discharge power limit value of the battery unit and the charge and discharge power limit value of the inverter in each photovoltaic energy storage inversion single machine system obtained in the step S11, combining the current state of each photovoltaic energy storage inversion single machine system, and determining the maximum allowable feed power and the maximum allowable charge power of each photovoltaic energy storage inversion single machine system;
For each single-machine system, determining the maximum allowable feed power and the maximum allowable charging power of each single-machine system according to the charging and discharging power limit value of the battery unit and the charging and discharging power limit value of the inverter obtained in the step S11 by combining the current state of each single-machine system.
For each single-machine system, uniformly setting an ideal preset threshold range of the battery unit SOC as follows: the first threshold value is equal to or less than the SOC and is equal to or less than the second threshold value. The aim of each single-machine system is to keep the SOC of the battery unit within the ideal preset threshold range as much as possible, and once the current SOC is smaller than a first threshold, a first flag bit is started; once the current SOC is greater than a second threshold, a second flag bit is turned on; when the first threshold value is smaller than or equal to the SOC and smaller than or equal to the second threshold value, the states of the first zone bit and the second zone bit are different according to different conditions. If the SOC of the battery unit is within the range that the first threshold value is less than or equal to the SOC and less than or equal to the second threshold value when the photovoltaic energy storage inversion single machine system is started, a third marking bit is started; if the SOC of the battery unit is within the range from less than the first threshold value or greater than the second threshold value to less than or equal to the first threshold value and less than or equal to the second threshold value after the photovoltaic energy storage inversion single machine system is started, the flag bit is kept unchanged, that is, the SOC of the battery unit may be the same as the flag bit when the SOC of the battery unit is less than or equal to the first threshold value or greater than the second threshold value when the SOC of the battery unit is less than or equal to the first threshold value and less than or equal to the second threshold value.
And determining the maximum allowable feed power and the maximum allowable charging power of the corresponding stand-alone system according to the states (on or off) of the first flag bit and the second flag bit. The first threshold value can be any value of 80% -90%, and the second threshold value can be any value of 91% -99%.
Taking an ideal preset threshold range of SOC of the battery unit as an example, SOC is 90% or more and 96% or less, the following description is made in conjunction with fig. 2 and 3:
As shown in fig. 3, under the working condition of a battery unit, when the system is just started at time t1 and the SOC at time t1 is smaller than the first threshold value by 90%, the first flag bit is turned on (ChgFlag =1). At the time t1-t2, the first flag bit is always in an on state (ChgFlag =1); at time t2, if SOC is greater than the second threshold value by 96%, the first flag bit is turned off (ChgFlag =0), and the second flag bit is turned on (ChgFullFlag =1); at the time t2-t3, the second flag bit is always in an on state (ChgFullFlag =1); at time t3, if SOC is less than 90% of the first threshold, the second flag is turned off (ChgFullFlag =0), and the first flag is turned on (ChgFlag =1); at time t3-t4, the first flag bit is still in the on state (ChgFlag =1).
As shown in another working condition of the battery unit in fig. 4, the system is just started at time t7, the SOC is more than or equal to 90% and less than or equal to 96% at time t7, and neither the first flag bit nor the second flag bit is opened (ChgFlag =0 and ChgFullFlag =0); at time t8, SOC is greater than 96% of the second threshold, and the second flag bit is turned on (ChgFullFlag =1); at time t8-t9, the second flag bit is always in an on state (ChgFullFlag =1); at time t9, if SOC is less than 90% of the first threshold, the second flag is turned off (ChgFullFlag =0), and the first flag is turned on (ChgFlag =1); at time t9-t10, the first flag is still in the on state (ChgFlag =1).
As can be seen from the above examples, each stand-alone system may be in any of the following 5 states:
State 1: single battery cell SOC >96%, single ChgFullFlag =1;
State 2: single battery cell SOC <90%, single ChgFlag =1;
state 3: the SOC of a single battery unit is more than or equal to 90 percent and less than or equal to 96 percent, and the single battery unit ChgFullFlag =1;
State 4: the SOC of a single battery unit is more than or equal to 90 percent and less than or equal to 96 percent, and the single battery unit ChgFlag =1;
State 5: the single battery unit SOC is more than or equal to 90% and less than or equal to 96%, the single battery unit ChgFullFlag =0 and ChgFlag =0.
When the stand-alone ChgFlag =1, the minimum value of [ the charging power limit of the battery unit, the charging power limit of the inverter ] is taken as the maximum allowable charging power, and the maximum allowable feeding power is 0.
When the single unit ChgFullFlag =1, the minimum value of the [ discharge power limit of the battery unit, discharge power limit of the inverter ] is taken as the maximum allowable feed power, and the maximum allowable charge power is 0.
When the stand-alone ChgFullFlag =0 and ChgFlag =0, the maximum allowable charging power is 0 and the maximum allowable feeding power is 0.
S13: adding the maximum allowable feed power of all the photovoltaic energy storage inversion single machine systems to obtain the maximum allowable feed power of the photovoltaic energy storage inversion parallel machine systems; and adding the maximum allowable charging power of all the photovoltaic energy storage inversion single machine systems to obtain the maximum allowable charging power of the photovoltaic energy storage inversion parallel machine system.
The maximum allowable feed power of the current parallel machine system is equal to the sum of the maximum allowable feed power of each single machine system; the maximum allowable charging power is equal to the sum of the maximum allowable charging power of each stand-alone system.
S2: and acquiring the total power of the load, and carrying out energy scheduling according to the total power of the load, the maximum allowable feed power and the maximum allowable charging power of the photovoltaic energy storage inversion parallel operation system.
The energy regulation is performed in combination with the maximum allowable feed power Pdischa _max, the maximum allowable charge power Pcha _max, and the total load power PLoad of the current parallel system.
The maximum allowable feed power Pdischa _max satisfies the demands of each item in order of priority [ load, battery cell that is not full, grid ]. The photovoltaic energy storage inversion parallel operation system preferentially meets the requirement of a load, energy remains after the load is met, the energy is supplied to battery units in other single machine systems, and when the energy remains, the energy is supplied to a power grid. Therefore, in this embodiment, the power supply power is recalculated according to the load, i.e. the battery unit which is not fully charged (the maximum allowable charging power of the single machine is from large to small/from small to large/the serial number sequence of the inverter, etc.), and the power supply power is fed by the power supply power first stage, so that electricity can be bought from the power supply as little as possible or less, and the maximization of economic benefit can be realized.
The step S2 specifically comprises the following steps:
S21: judging whether Pdischa _max > PLoad; if yes, go to step S22; if not, step S25 is performed.
S22: calculating a first residual power P1: p1= Pdischa _max-PLoad, and judging whether P1> Pcha _max, if yes, executing step S23; if not, step S24 is performed.
S23: calculating a second residual power P2: p2=p1-Pcha _max, P2 is fed into the grid;
S24: selecting a single system with the maximum allowable charging power not equal to 0, and distributing P1 according to a first preset rule;
the first preset rule may be, for example, the order of the number of the stand-alone system from small to large/from large to small, or the maximum allowable charging power of the stand-alone system from small to large/from large to small.
S25: the parallel machine system fully supplies Pdischa _max to the load, and in addition, calculates the supplementary power P, p=pload-Pdischa _max. The power supply P is distributed to each single machine system according to a second preset rule.
The second preset rule may be, for example: the serial numbers of the single machine systems are in the order from small to big/from big to small; or picking out the single system with the maximum allowable feed power not equal to 0, and recalculating the feed power of the single system according to the sequence of the feed power from small to large/from large to small.
It should be noted that: the feed power is not equal to the maximum allowable feed power; the precondition of the maximum allowable power supply obtained by the calculation is that in order to keep the SOC of the battery unit as far as possible within the ideal preset threshold range, and at this time Pdischa _max cannot meet the requirement of the load, it is necessary that a certain/some stand-alone system cannot meet the requirement of the ideal preset threshold range of the SOC of the battery unit, and additional discharge is required to meet the requirement of the load, for example, at time t9-t10 in fig. 4, the power supply is recalculated, wherein the power supply is [ the discharge power limit of the inverter, the discharge power limit of the battery unit ].
The control method of the photovoltaic energy storage inversion parallel operation system provided by the preferred embodiment of the invention can achieve the following effects:
(1) The PV energy is fully utilized when a plurality of energy storage inverters are connected in parallel, so that waste is avoided;
(2) Simplifying the PV feeding strategy, and realizing flexible dispatching of DC side (including battery units and direct current side of PV) photovoltaic energy by a simple logic method;
(3) The feed power of the AC side (including the load and the alternating current side of the power grid) does not change with the change of the PV power of the DC side, and the effect of stabilizing the feed power of the AC side is achieved.
According to the photovoltaic energy storage inversion parallel operation system and the control method thereof, power supply is distributed in sequence according to the maximum allowable feed power and the maximum allowable charging power of the parallel operation system and the priority order of the system load, the battery unit of the underfilled single machine system and the power grid to regulate and control energy, the PV energy is fully utilized, and the waste of the PV energy is avoided.
According to the photovoltaic power generation system, photovoltaic and the energy storage power supply are regarded as a whole, the photovoltaic energy is regarded as all flowing to the energy storage power supply (battery unit), the energy storage power supply is anchored, the alternating-current side of the inverter is used as a unified inlet and outlet of the energy, decoupling of photovoltaic power generation and a power grid port is achieved, the power grid port is not affected by instability of photovoltaic power generation completely, meanwhile, energy dispatching can be achieved only by obtaining maximum allowed power supply and maximum allowed charging power, and a PV power supply strategy is simplified.
The maximum allowable feed power and the maximum allowable charging power of the parallel operation system fully consider the SOC variation of the battery unit, and keep the SOC of each single machine system within a threshold range as much as possible, thereby achieving the effect of stabilizing the feed power of an AC side (including the load and the AC side of a power grid).
The background section of the present invention may contain background information about the problem or environment of the present invention rather than the prior art described by others. Accordingly, inclusion in the background section is not an admission of prior art by the applicant.
The foregoing is a further detailed description of the invention in connection with specific/preferred embodiments, and it is not intended that the invention be limited to such description. It will be apparent to those skilled in the art that several alternatives or modifications can be made to the described embodiments without departing from the spirit of the invention, and these alternatives or modifications should be considered to be within the scope of the invention. In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "preferred embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction. Although embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope as defined by the appended claims.
Claims (7)
1. The photovoltaic energy scheduling method of the photovoltaic energy storage inversion parallel operation system is characterized by comprising the following steps of:
S1: the method comprises the steps of respectively obtaining maximum allowed feed power and maximum allowed charging power of each photovoltaic energy storage inversion single machine system in a photovoltaic energy storage inversion parallel machine system, and obtaining the maximum allowed feed power and the maximum allowed charging power of the photovoltaic energy storage inversion parallel machine system according to the maximum allowed feed power and the maximum allowed charging power of each photovoltaic energy storage inversion single machine system, wherein each photovoltaic energy storage inversion single machine system respectively comprises a photovoltaic, an inverter and a battery unit;
s2: acquiring total power of a load, and carrying out energy scheduling according to the total power of the load and the maximum allowable feed power and the maximum allowable charging power of a photovoltaic energy storage inversion parallel operation system;
The step S2 specifically includes:
S21: acquiring the total power of the load, judging whether the maximum allowable feed power of the photovoltaic energy storage inversion parallel operation system is larger than the total power of the load, if so, executing the step S22, and if not, executing the step S25;
S22: calculating first residual power, wherein the first residual power is equal to the total power of the maximum allowable feed power of the photovoltaic energy storage inversion parallel operation system and the load is reduced, judging whether the first residual power is larger than the maximum allowable charging power of the photovoltaic energy storage inversion parallel operation system, if so, executing step S23, and if not, executing step S24;
S23: calculating second residual power, wherein the second residual power is equal to the maximum allowable charging power of the first residual power dimming photovoltaic energy storage inversion parallel operation system, and feeding the second residual power into a power grid;
S24: picking out the photovoltaic energy storage inverter single machine system with the maximum allowable charging power not equal to 0, and distributing the first residual power according to a first preset rule, wherein the distribution according to the first preset rule means that: the serial numbers of the selected photovoltaic energy storage inversion single machine systems are sequentially distributed from small to large or from large to small, or the maximum allowable charging power of the selected photovoltaic energy storage inversion single machine systems is sequentially distributed from small to large or from large to small;
S25: supplying all the maximum allowable feed power of the photovoltaic energy storage inversion parallel operation system to the load, and calculating the supplementary electric power, wherein the supplementary electric power is equal to the maximum allowable feed power of the total power reduction photovoltaic energy storage inversion parallel operation system of the load, and the supplementary electric power is distributed according to a second preset rule, wherein the distribution according to the second preset rule means that: and picking out the photovoltaic energy storage inversion single machine system with the maximum allowable feed power not equal to 0 according to the sequence of the serial numbers of the photovoltaic energy storage inversion single machine system from small to large or from large to small, and sequentially distributing the feed power of the selected photovoltaic energy storage inversion single machine system according to the sequence of the serial numbers of the photovoltaic energy storage inversion single machine system from small to large or from large to small, wherein the feed power of the photovoltaic energy storage inversion single machine system takes the value as the smaller of the discharge power limit value of a battery unit and the discharge power limit value of an inverter.
2. The photovoltaic energy scheduling method according to claim 1, wherein step S1 specifically comprises:
S11: respectively acquiring a charging and discharging power limit value of a battery unit and a charging and discharging power limit value of an inverter in each photovoltaic energy storage inversion single machine system;
s12: according to the charging and discharging power limit value of the battery unit and the charging and discharging power limit value of the inverter in each photovoltaic energy storage inversion single machine system obtained in the step S11, combining the current state of each photovoltaic energy storage inversion single machine system, and determining the maximum allowable feed power and the maximum allowable charging power of each photovoltaic energy storage inversion single machine system;
S13: adding the maximum allowable feed power of all the photovoltaic energy storage inversion single machine systems to obtain the maximum allowable feed power of the photovoltaic energy storage inversion parallel machine system; and adding the maximum allowable charging power of all the photovoltaic energy storage inversion single machine systems to obtain the maximum allowable charging power of the photovoltaic energy storage inversion parallel machine system.
3. The photovoltaic energy scheduling method according to claim 2, wherein step S12 further comprises: and determining the current state of each photovoltaic energy storage inversion single machine system according to the preset threshold range of the battery unit and the current SOC value of the battery unit of each photovoltaic energy storage inversion single machine system, wherein the preset threshold range of the battery unit is larger than or equal to a first threshold and smaller than or equal to a second threshold.
4. The method for photovoltaic energy scheduling according to claim 3,
When the current SOC value of the battery unit of the photovoltaic energy storage inversion single machine system is smaller than the first threshold value, marking the photovoltaic energy storage inversion single machine system as a first marking state;
When the current SOC value of the battery unit of the photovoltaic energy storage inversion single machine system is larger than the second threshold value, marking the photovoltaic energy storage inversion single machine system as a second marking state;
If the SOC of the battery unit is within a preset threshold value range when the photovoltaic energy storage inversion single machine system is started, marking the photovoltaic energy storage inversion single machine system as a third marking state; if the SOC of the battery unit enters the preset threshold range from the non-preset threshold range after the photovoltaic energy storage inversion single machine system is started, marking the state marked by the photovoltaic energy storage inversion single machine system before entering the preset threshold range as the state of the photovoltaic energy storage inversion single machine system when the SOC of the battery unit is within the preset threshold range.
5. The method of photovoltaic energy scheduling according to claim 4,
When the photovoltaic energy storage inversion single machine system is marked as a first marking state, the maximum allowable feed power value of the photovoltaic energy storage inversion single machine system is 0, and the maximum allowable charging power value is the smaller of the charging power limit value of the battery unit and the charging power limit value of the inverter;
when the photovoltaic energy storage inversion single machine system is marked as a second marked state, the maximum allowable feed power value of the photovoltaic energy storage inversion single machine system is smaller than the discharge power limit value of the battery unit and the discharge power limit value of the inverter, and the maximum allowable charge power value is 0;
When the photovoltaic energy storage inversion single machine system is marked as a third marking state, the maximum allowable feed power of the photovoltaic energy storage inversion single machine system is 0, and the maximum allowable charging power is 0.
6. The method of any one of claims 3 to 5, wherein the first threshold has a value ranging from 80% to 90% and the second threshold has a value ranging from 91% to 99%.
7. A photovoltaic energy storage inversion parallel machine system, characterized by comprising a plurality of photovoltaic energy storage inversion single machine systems, wherein each photovoltaic energy storage inversion single machine system comprises a photovoltaic, an inverter and a battery unit, each inverter is connected with the corresponding photovoltaic and battery unit, the alternating current side of each inverter is connected in parallel and is connected with a load and a power grid, and the photovoltaic energy storage inversion parallel machine system performs photovoltaic energy dispatching by adopting the photovoltaic energy dispatching method according to any one of claims 1 to 6.
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